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A set of beads made of glass, gastropod mollusk shell, and fishbone from a Swahili occupation level on Ibo Island (northern Mozambique) is dated to the eleventh and twelfth centuries AD. The chemical composition of the glass beads and their chromophores, and the shell and fishbone materials, are studied to understand the local and trading provenance of these items. Representative samples of each material, including two flat glass shards, were characterized using optical microscopy, field emission scanning electron microscopy (FESEM) with energy dispersive X-ray (EDS) microanalysis attached, UV-Vis-NIR spectrophotometry, and X-ray diffraction (XRD). Glass beads represent 60% of the bead assemblage. The shell and fishbone beads are 38.75% and 1.25%, respectively. Three groups of glasses were identified: (1) mineral-soda alumina glass beads associated with the recently identified m-Na-Al 6 group that come from Western India; (2) vegetal-soda alumina, represented by one flat glass shard probably from the Middle East, and beads of v-Na-Al glass of type A that came from Central Asia; and (3) conventional soda-lime silicate glasses, of modern chronology and probable European origin. Groups 1 and 2 show a variety of chromophores, both ionic and colloidal. A ruby-color bead was also identified as belonging to the Na2O-ZnO-SiO2 system and colored with cadmium sulfoselenide colloids, but this was of modern chronology. Shell beads were made from Lambis lambis gastropod mollusk shells and were locally produced. The fishbone beads may have been from a cartilaginous fish of the Chondrichthyes class, but it is difficult to specify the taxonomical level. The results of the analysis suggest that Ibo Island was integrated very early into the Swahili trade networks of the Indian Ocean. [ABSTRACT FROM AUTHOR]

Gastropod molluscs are among the most diverse and abundant animals in the oceans, and are successful colonizers of terrestrial and freshwater environments. Past phylogenetic efforts to resolve gastropod relationships resulted in a range of conflicting hypotheses. Here, we use phylogenomics to address deep relationships between the five major gastropod lineages--Caenogastropoda, Heterobranchia, Neritimorpha, Patellogastropoda and Vetigastropoda--and provide one congruent and well-supported topology. We substantially expand taxon sampling for outgroups and for previously underrepresented gastropod lineages, presenting new transcriptomes for neritimorphs and patellogastropods. We conduct analyses under maximum- likelihood, Bayesian inference and a coalescent-based approach, accounting for the most pervasive sources of systematic errors in large datasets: compositional heterogeneity, site heterogeneity, heterotachy, variation in evolutionary rates among genes, matrix completeness, outgroup choice and gene tree conflict. We find that vetigastropods and patellogastropods are sister taxa, and that neritimorphs are the sister group to caenogastropods and heterobranchs. We name these two major unranked clades Psilogastropoda and Angiogastropoda, respectively. We additionally provide the first genomic-scale data for internal relationships of neritimorphs and patellogastropods. Our results highlight the need for reinterpreting the evolution of morphological and developmental characters in gastropods, especially for inferring their ancestral states. [ABSTRACT FROM AUTHOR]

Using landform evolution and lake sediment records to reconstruct Quaternary environmental changes requires reliable chronology. However, there is an ongoing debate regarding the fossil shells of aquatic gastropods in carbonate rock area to be used for radiocarbon dating. The focus of this debate is whether living gastropods incorporate the dead carbon, which would affect the accuracy of the dating results. Living aquatic gastropods were selected from habitats on carbonate terrain in arid region. In this study, 64 shell samples from living gastropods, including Cipangopaludina chinensis , Gyraulus convexiusculus , and Radix auricularia , collected from the Alashan Plateau of northwestern China, were dated by accelerator mass spectrometry (AMS) 14 C dating. The results revealed that only five samples (~8%) from the same site contained no dead carbon. The other 59 samples (~92%) contained dead carbon in various amounts: ~59% samples contained 0–10% dead carbon, and ~33% samples contained more than 10% dead carbon. Of the samples, 56 were Radix auricularia and their 14 C ages varied from present to 3253 cal yr BP. Two of the samples were Gyraulus convexiusculus samples dated at 379 and 290 cal yr BP which are highly consistent with 14 C ages of Radix auricularia samples from the same site. The other six Cipangopaludina chinensis samples were dated at 407–863 cal yr BP. Thus, most of living aquatic gastropods from habitats on carbonate terrain contained dead carbon. The amount of dead carbon in the gastropod shells was nonselective among the three species. Radiocarbon dating of aquatic gastropod shells may not be useful for studying processes that occurred over multi-millennial timescales at different localities in areas of carbonate rock. It is difficult to establish high-resolution chronologies using 14 C ages of gastropod shells in arid regions with carbonate rocks unless the limestone effect has been corrected. [ABSTRACT FROM AUTHOR]

Sessile organisms are reliant on the use of refugia or chemical and physical defences to avoid or reduce attacks from predators. Many solitary ascidians possess a thick leathery outer tunic, sometimes reinforced with inorganic inclusions, that generally acts to deter predators. The genus Herdmania is remarkable among ascidians in possessing an abundance of barbed needle-like calcareous spicules in both the external tunic and the internal mantle. Our focus was on a habitat-forming subtidal ascidian – Herdmania grandis . We questioned why a large ascidian possessing a leathery test would possess spicules within the mantle – an apparent defence within a defence. We first quantified variation in spicule size and density within animals. Second, we examined the size and density of spicules for individuals of a range of sizes. Third, we incorporated these spicules at natural concentrations into feeding discs and tested their ability to deter gastropod predators that specialise in consuming ascidians and an asteroid that is considered a generalist consumer. Finally, we examined survivorship of lab-reared ascidian recruits when exposed to the starfish predator. Spicules constituted up to 30% dry weight (DW) of the tunic and an astounding 57% DW of the body wall (mantle). Spicules were significantly smaller in the contractile regions of the animal (the siphon and branchial basket) and were also found in lower densities, though not significantly. Mantle spicules were effective feeding deterrents; control feeding discs, lacking spicules, were consumed at three times the rate of discs with spicules (p < 0.05) by specialist ascidian predators, the Ranellid gastropods Cabestana spengleri and Ranella australasia . In contrast, we did not detect a significant difference in the consumption of feeding discs by the seastar Meridiastra calcar . In addition, the seastar reduced survivorship of 90 day old lab-reared recruits by four-fold. We contend that the primary defence mechanism of this ascidian is the leathery test and that this is effective against generalist consumers. The second line of defence – spicules in the mantle –is to thwart gastropod predators that bypass the tunic either by boring through it or by inserting their proboscis directly into soft tissues of their prey via the siphons. The presence of both a leathery tunic and spicules in H. grandis probably contributes to the dominance of this species on shallow subtidal reefs in southeastern Australia, where it is an important habitat-forming species. Our findings confirm the importance of considering a range of consumer strategies and life history stages in assessing potential control of engineering species by predation. [ABSTRACT FROM AUTHOR]

The Balkan genus Spelaeodiscus Brusina, 1886 is revised based on museum collections and newly collected samples from Montenegro and Albania. The following species and subspecies are introduced as new to science: Spelaeodiscus albanicus edentatus Páll-Gergely & P. L. Reischütz, ssp. n. (southern Montenegro and northern Albania), Spelaeodiscus densecostatus Páll-Gergely & A. Reischütz, sp. n., Spelaeodiscus hunyadii Páll-Gergely & Deli, sp. n., Spelaeodiscus latecostatus Páll-Gergely & Erőss, sp. n. (all three from southern Montenegro), Spelaeodiscus unidentatus acutus Páll-Gergely & Fehér, ssp. n., and Spelaeodiscus virpazarioides Páll-Gergely & Fehér, sp. n. (both from northern Albania). For all species and subspecies diagnoses and suggestions for conservation status assessments according to IUCN criteria are provided. An overview is given regarding the habitat preference of Spelaeodiscus species, and the "scratch and flotate" method to collect subterranean gastropods. [ABSTRACT FROM AUTHOR]

The anthropozoonotic metastrongyloid nematodes Angiostrongylus cantonensis and Angiostrongylus costaricensis, as well as Angiostrongylus vasorum, Crenosoma vulpis, Aelurostrongylus abstrusus and Troglostrongylus brevior are currently considered as emerging gastropod-borne parasites and have gained growing scientific attention in the last years. However, the knowledge on invertebrate immune responses and on how metastrongyloid larvae are attacked by gastropod immune cells is still limited. This work aims to describe an in vitro system to investigate haemocyte-derived innate immune responses of terrestrial gastropods induced by vital axenic metastrongyloid larvae. We also provide protocols on slug/snail management and breeding under standardized climate conditions (circadian cycle, temperature and humidity) for the generation of parasite-free F0 stages which are essential for immune-related investigations. Adult slug species (Arion lusitanicus, Limax maximus) and giant snails (Achatina fulica) were maintained in fully automated climate chambers until mating and production of fertilized eggs. Newly hatched F0 juvenile specimens were kept under parasite-free conditions before experimental use. An improved protocol for gastropod haemolymph collection and haemocyte isolation was established. Giemsa-stained haemolymph preparations showed adequate haemocyte isolation in all three gastropod species. Additionally, a protocol for the production of axenic first and third stage larvae (L1, L3) was established. Haemocyte functionality was tested in haemocyte-nematode-co-cultures. Scanning electron microscopy (SEM) and light microscopy analyses revealed that gastropod-derived haemocytes formed clusters as well as DNA-rich extracellular aggregates catching larvae and decreasing their motility. These data confirmthe usefulness of the presented methods to study haemocyte-mediated gastropod immune responses to better understand the complex biology of gastropod-borne diseases. [ABSTRACT FROM AUTHOR]

Mimicry is one of the best examples of coevolution. For a mimetic system to function, the mimic has to equal its model. Due to this close dependence, mimetic systems promise deep insights into modes and means of evolution. Mimicry is known to occur in many taxa across different groups of organisms. However, while a plethora of mimetic systems exist, cross-phyla convergences have only rarely been reported in shelled gastropods. Our literature survey brought to light several mimetic systems including gastropods (as model or mimic), all of them in either a marine or a terrestrial setting. We here report on the first potential case of mimicry involving freshwater snails. We found larval cases of European Helicopsyche caddisfly to closely resemble Valvata gastropod shells in shape and size. In particular, stunning is the detailed similarity of features in these trichopteran cases to those characteristic for snail shells, for example, apex, aperture and umbilicus, hinting at a strong selection pressure to be involved. We discuss this unique case of mimicry that might hold unparalleled insight in mimetic relationships, taking into account alternative environmental factors and potential predatory dupes, in particular birds that might have successively caused the evolution of coiled cases in helicopsychid trichopterans. [ABSTRACT FROM AUTHOR]

In this study, we re-examine two species of freshwater gastropods of the genus Radix Montfort, 1810 (family Lymnaeidae), endemic to the geothermal springs in the Lake Baikal region in the southern part of eastern Siberia - Lymnaea (Radix) hakusyensis Kruglov et Starobogatov, 1989, and Lymnaea (Radix) thermobaicalica Kruglov et Starobogatov, 1989. The alleged species status of these endemics has been re-assessed by means of an integrative approach combining molecular genetic taxonomy techniques with the traditional methods based on shell and soft body morphology. Phylogenetic reconstructions were made using both mitochondrial ( COI) and nuclear ( ITS2) DNA markers. We used topotypic samples of both species and specimens sampled from other sites around Lake Baikal. The results demonstrate that the two endemic species are only synonyms of a widespread Holarctic species, Radix auricularia (Linnaeus, 1758), and represent its intraspecific morph (ecotype) adapted to living in thermal springs. A new synonymy is proposed: Thermoradix Kruglov et Starobogatov, 1989 = Radix Montfort, 1810 (syn. n.). [ABSTRACT FROM AUTHOR]

Vertebrates, cephalopods and arthropods are equipped with eyes that have the highest spatiotemporal resolution among the animal phyla. In parallel, only animals in these three phyla have visual arrestin specialized for the termination of visual signaling triggered by opsin, in addition to ubiquitously expressed β-arrestin that serves in terminating general G protein-coupled receptor signaling. Indeed, visual arrestin in Drosophila and rodents translocates to the opsin-rich subcellular region in response to light to reduce the overall sensitivity of photoreceptors in an illuminated environment (i.e. light adaptation). We thus hypothesized that, during evolution, visual arrestin has taken over the role of β-arrestin in those animals with eyes of high spatiotemporal resolution. If this is true, it is expected that β-arrestin plays a role similar to visual arrestin in those animals with low-resolution eyes. In the present study, we focused on the terrestrial mollusk Limax valentianus, a species related to cephalopods but that has only β-arrestin, and generated antibodies against β-arrestin. We found that β-arrestin is highly expressed in photosensory neurons, and translocates into the microvilli of the rhabdomere within 30 min in response to short wavelength light (400 nm), to which the Limax eye exhibits a robust response. These observations suggest that β-arrestin functions in the visual system of those animals that do not have visual arrestin. We also exploited anti-β-arrestin antibody to visualize the optic nerve projecting to the brain, and demonstrated its usefulness for tracing a visual ascending pathway. [ABSTRACT FROM AUTHOR]

We here report on the systematics, paleoecology and biostratigraphy of a rare, but diversified gastropod fauna found in the early Pliocene sediments of the Agia Triada section in the Falanthi Basin (Peloponnese, Greece). Sixty-one species belonging to forty-eight genera are identified, allowing biostratigraphic assignment to the Mediterranean Plio-Pleistocene Molluscan Unit 1 (MPPMU1). Planktonic foraminiferal biostratigraphic analyses indicate that the Agia Triada section correlates with Zones MPL2 and MPL3, corresponding to the latest Zanclean. A comparison is further carried out between the studied assemblages and those previously documented from the Atlantic coasts of Europe and the Mediterranean region. New information on the palaeobiogeography of early Pliocene gastropod fauna is given, as seven species from the Mediterranean, thirty-nine species from the eastern Mediterranean and forty-four species from Greece, are documented here for the first time. [ABSTRACT FROM AUTHOR]

Research on marine gastropod breeding in India is in its infancy and scanty literature is only available. To fill the lacunae, marine gastropods of three ornamentally valued and conservation important groups such as Cyprids, Strombids and Muricids were held under captivity and studied for their broodstock maintenance, spawning behaviour, larval rearing and metamorphosis into juveniles at the Shellfish Hatchery of Central Marine Fisheries Research Institute, Tuticorin. Valuable information on the focal themes of the article was obtained for Strombids and Muricids leading to the successful life cycle closing for Lambis lambis and Chicoreus virgineus are reported earlier. In the present study, experiments were conducted on aspects such as post-metamorphosed juvenile rearing up to 76 days post hatch for L. lambis, spawning, larval development and life cycle closing and reasonable level of juvenile production (8.8%) for Chicoreus ramosus. In addition, the primary observations on the captive breeding of Cypraea tigris with reference to its egg mass, brooding habit and early development is reported. However, while studying these groups few unanswered questions and bottle necks in their breeding nature, larval rearing and metamorphosis arose. The following account details the experiments conducted and results obtained in each of the focal themes of the paper and the constraints faced. [ABSTRACT FROM AUTHOR]

During the present investigation, Girgaon, Marine Drive, Haji Ali and Gorai Creek in Mumbai were selected for biodiversity assessment following a protocol for natural geography in shore areas. Fifty nine macrobenthic molluscs, arthropods, coelenterates and echinoderms at these sites were recorded. The maximum density of gastropods and clams was observed at Marine Drive shore. At Gorai Creek, there were plentiful Telescopium telescopium, Potamidus cingulatis, mudskipper and fiddler crabs. Studies shows that the biodiversity status of the selected sites varies with respect to location, type of substratum and season. Pollution was observed to have a noticeable effect on clams at Girgaon coast, where many Paphia textile shells were observed to be filled with mud and coated with black colour. [ABSTRACT FROM AUTHOR]

Temperature stress is one of the major threats to the economic and ecological sustainability of marine fisheries and aquaculture. The abalone aquaculture in China has been in development for more than twenty years, while summer mortality for Pacific abalone ( Haliotis discus hannai ) is still the most serious issue for its aquaculture in southern China. Therefore, an effective and accurate measurement for evaluating the abalone's thermal tolerance is crucial for both scientific researchers and farmers. In this study, we evaluate the thermal tolerance of two abalone species: H. discus hannai (DD), H. gigantea (GG) and their offspring H. gigantea ♀ × H. discus hannai ♂ (GD) using Arrhenius break temperatures (ABT) of cardiac performance. These three groups possessed different thermal limits, as indicated by ABT, GD (32.50 ± 0.71 °C) > GG (31.30 ± 1.52 °C) > DD (30.00 ± 1.23 °C). The results were similar to further assessments of lethal temperature, Kaplan–Meier cumulative survival curves and critical thermal maximum. These results indicate that cardiac performance is an effective method to assess heat tolerance and can represent the different physiological statuses of abalones. Moreover, the results also suggested that global warming may have a profound influence on abalone aquaculture in China in the near future. Statement of relevance The results of the present study may facilitate in better understanding the difference on the thermal tolerance ability of H. discus hannai , H. gigantea and their offspring H. gigantea ♀ × H. discus hannai ♂ using Arrhenius break temperatures (ABT) of cardiac performance. The results were similar to further assessments of lethal temperature, Kaplan–Meier cumulative survival curves and critical thermal maximum. These findings indicate that cardiac performance is an effective method to assess heat tolerance and can represent the different physiological statuses of abalone. The ABT of cardiac performance could afford an efficient method to predict abalone thermal performance, which would be greatly beneficial in aquaculture and breeding projects. Moreover, it may have potentially broad application in the study of thermal tolerance of abalone and other commercially aquaculture species. [ABSTRACT FROM AUTHOR]

Mitogen–activated protein kinase (MAPK) is involved in the regulation of cellular events by mediating signal transduction pathways. MAPK1 is a member of the extracellular-signal regulated kinases (ERKs), playing roles in cell proliferation, differentiation, and development. This is mainly in response to growth factors, mitogens, and many environmental stresses. In the current study, we have characterized the structural features of a homolog of MAPK1 from disk abalone (AbMAPK1). Further, we have unraveled its expressional kinetics against different experimental pathogenic infections or related chemical stimulants. AbMAPK1 harbors a 5′ untranslated region (UTR) of 23 bps, a coding sequence of 1104 bps, and a 3′ UTR of 448 bp. The putative peptide comprises a predicted molecular mass of 42.2 kDa, with a theoretical p I of 6.28. Based on the in silico analysis, AbMAPK1 possesses two N -glycosylation sites, one S_TK catalytic domain, and a conserved His-Arg-Asp domain (HRD). In addition, a conservative glycine rich ATP-phosphate-binding loop and a threonine-x-tyrosine motif (TEY) important for the autophosphorylation were also identified in the protein. Homology assessment of AbMAPK1 showed several conserved regions, and ark clam ( Aplysia californica ) showed the highest sequence identity (87.9%). The phylogenetic analysis supported close evolutionary kinship with molluscan orthologs. Constitutive expression of AbMAPK1 was observed in six different tissues of disk abalone, with the highest expression in the digestive tract, followed by the gills and hemocytes. Highest AbMAPK1 mRNA expression level was detected at the trochophore developmental stage, suggesting its role in abalone cell differentiation and proliferation. Significant modulation of AbMAPK1 expression under pathogenic stress suggested its putative involvement in the immune defense mechanism. [ABSTRACT FROM AUTHOR]

A systematic account of the upper lower-lower middle Miocene upper Burdigalian to lower Langhian gastropod assemblage found in the Cantaure Formation of the Paraguana Peninsula of Venezuela is given. In this work, 393 species are recorded belonging to 259 genera and subgenera, of which 72 are left in open nomenclature. Five new genera are proposed: Dentimides n. gen., Cantaurea n. gen., Glyptophos n. gen., Torqueoliva n. gen., and Marginocystiscus n. gen. Ninety species are described as new: Agathistoma paraguanensis n. sp., Lithopoma minutum n. sp., Marevalvata basilaevis n. sp., Neritina nunoi n. sp., N. meesi n. sp., N. isabelae n. sp., N. daani n. sp., N. seani n. sp., N. daisyae n. sp., Ochetoclava jungi n. sp., Hemisinus miocenicus n. sp., Charadreon wesselinghi n. sp., Stephopoma ruedigeri n. sp., Teinostoma olssoni n. sp., Solariorbis pilsbryi n. sp., Woodringilla lentiformis n. sp., Cochliolepis costata n. sp., Cyclostremiscus basicostatus n. sp., C. forticarinatus n. sp., Cantaurea imperforata n. sp., Trochita angusticostata n. sp., T. paucicostata n. sp., Macromphalina partimsculpturata n. sp., Erato falconensis n. sp., Polinices jungi n. sp., Elachisina crassilabrata n. sp., Ficus yesimae n. sp., Cerithiopsis (s. l.) wesselinghi n. sp., C. (s. l.) moritzhoernesi n. sp., Seila cantaurana n. sp., Gyroscala cantaurana n. sp., G. lilliputiana n. sp., G. paraguanensis n. sp., Scalenostoma conicum n. sp., Solenosteira (Fusinosteira) primitiva n. sp., Hesperisternia parva n. sp., H. vermeiji n. sp., Antillophos elongatus n. sp., Engoniophos schmidti n. sp., Glyptophos furreri n. sp., Metaphos caribbensis n. sp., Strombinophos pilsbryi n. sp., Colubraria praeprocera n. sp., Metula quasilaevis n. sp., Aesopus faberi n. sp., Costoanachis paraguanensis n. sp., C. lacrima n. sp., Mazatlania parva n. sp., Mitrella longispira n. sp., M. tutata n. sp., Steironepion variabile n. sp., Zanassarina phosiformis n. sp., Dorsina peterjungi n. sp., Nassarius kugleri n. sp., Nanarius gardnerae n. sp., Cymia hodsonorum n. sp., Conomitra cantaurana n. sp., Torqueoliva strictotorquata n. sp., Olivella robustodentata n. sp., O. paucidentata n. sp., Volvarina occultospira n. sp., Marginocystiscus subtilplicatus n. sp., Chelyconus manueltenorioi n. sp., Gradiconus johntuckeri n. sp., Glyptaesopus crocotillus n. sp., G. tuckeri n. sp., Glyphostoma inornatum n. sp., G. pauciornatum n. sp., Euglyphostoma wendelli n. sp., Acmaturris echinata n. sp., Agladrillia labiospinosa n. sp., A. falconensis n. sp., Clathrodrillia jungi n. sp., C. pupaeformis n. sp., C. totocostata n. sp., Globidrillia lanceolata n. sp., G. minutissima n. sp., Fusiturricula capeloi n. sp., Hindsiclava wiedenmayeri n. sp., Knefastia aenigmatica n. sp., K. etteri n. sp., Megasurcula centroamericana n. sp., Gemmula woodringi n. sp., Terebra harzhauseri n. sp., T. apporrecta n. sp., T. kronenbergi n. sp., Strioterebrum sinuosocostatum n. sp., Ringicula collaris n. sp., Atys gravidus n. sp., and Pyrunculus totostriatus n. sp. One species from the lower Pliocene Araya Formation of Cubagua, Venezuela, is described as new: Knefastia cubaguaensis n. sp. The following taxonomic changes are made: Persicula zuliana F. Hodson, 1927, and P. mirandana F. Hodson, 1927, are here considered synonyms, and as first revisers, the name P. mirandana is chosen. Narona wiedenmeyeri [sic] Landau, Petit, Etter, & Silva, 2012, is corrected to N. wiedenmayeri. Vasum quirosense F. Hodson, 1931, is considered a subjective synonym of Vasum haitense (G. B. Sowerby I, 1850). The Cantaure fauna corresponds to both soft and hard bottom habitats. Most of the assemblage suggests fully marine conditions with sandy bottom, coral, and rocky habitat, probably deposited in the shallow subtidal zone. Seagrass communities are conspicuously absent from the Cantaure assemblages. A small cohort of taxa suggests brackish conditions and a few groups of taxa are from fresh water. These are uncommon and usually represented by worn specimens, suggesting some degree of transport from river outflow and possibly lagoonal environments nearby. The importance of the assemblage is highlighted, because it is the richest southern Caribbean Miocene assemblage studied so far, comparable in diversity to the well-documented and roughly coeval Chipola Formation of northwestern Florida. The generic composition is similar to that of other lower Miocene Caribbean assemblages, however, the fauna is highly endemic at the species level, sharing relatively few species with other coeval Gatunian or Caloosahatchian assemblages. As is characteristic of Gatunian faunas, the species are relatively short-lived, with few surviving to the present day. At the generic level, the most striking difference between the Cantaure assemblage and the southern Caribbean present-day faunas is the presence of paciphile genera, that is, genera that during the Neogene had widespread distributions throughout the Pacific and the Atlantic Gatunian biogeographical province, but during or subsequent to the closure of the Central American Seaway became restricted to the Pacific side of their originally wider distributions. Even within extant genera in the tropical American region, the lower Miocene Cantaure species' closest similarities are often found among their Panamic Pacific congeners rather than their Caribbean or western Atlantic ones. [ABSTRACT FROM AUTHOR]

A gonadotropin-releasing hormone (GnRH)-like molecule was previously identified in a gastropod, Aplysia californica, and named ap-GnRH. In this study, we cloned the full-length cDNA of a putative ap-GnRH receptor (ap-GnRHR) and functionally authenticated this receptor as a bona fide ap-GnRHR. This receptor contains two potential translation start sites, each accompanied by a Kozak sequence, suggesting the translation of a long and a short form of the receptor is possible. The putative ap-GnRHR maintains the conserved structural motifs of GnRHR-like receptors and shares 45% sequence identity with the octopus GnRHR. The expression of the putative ap-GnRHR short form is ubiquitous in all tissues examined, whereas the long form is only expressed in parts of the central nervous system, osphradium, small hermaphroditic duct, and ovotestis. The cDNA encoding the long or the short receptor was transfected into the Drosophila S2 cell line and subject to a radioreceptor assay using 125I-labeled ap-GnRH as the radioligand. Further, the transfected cells were treated with various concentrations of ap-GnRH and measured for the accumulation of cAMP and inositol monophosphate (IP1). Radioreceptor assay revealed that only the long receptor bound specifically to the radioligand. Further, only the long receptor responded to ap-GnRH with an increased accumulation of IP1, but not cAMP. Our studies show that despite the more prevalent expression of the short receptor, only the long receptor is the functional ap-GnRHR. Importantly, this is only the second report on the authentication of a protostome GnRHR, and based on the function and the phylogenetic grouping of ap-GnRHR, we suggest that this receptor is more similar to protostome corazonin receptors than chordate GnRHRs. [ABSTRACT FROM AUTHOR]

Contemporary climate and deglaciation history have received strong support as drivers of species richness and composition for several European taxa. We explored the influence of these factors on patterns of species richness and faunal composition of 244 freshwater gastropod species from 898 European lakes. We evaluated the influence of late Pleistocene deglaciation and seven physiographical and climatic factors on gastropod distributions using multiple linear regression models. We investigated species beta diversity patterns and the influence of species dispersal abilities and/or environment on species composition between lake subsets with different deglaciation history. Contemporary factors and deglaciation history explain parts of variation in species richness across European lakes. Beta diversity analysis revealed moderate to high differences in species composition between the predefined groups. Patterns of species replacement and species loss indicate that lacustrine gastropod faunas of formerly glaciated areas are subsets of non-glaciated ones. Dispersal limitations and environmental gradients control patterns of beta diversity within different lake subsets. We find strong support that the distribution of European limnic gastropods, at least partially, carries the imprint of the last Ice Age. The differences in species richness and composition point towards a gradual, ongoing process of species recolonization after deglaciation. [ABSTRACT FROM AUTHOR]

The present paper covers 77 species and six subspecies of naticid gastropods occurring in the Eocene, Oligocene and Miocene units of Northern Italy; all are described and commented on in the systematic account. Forty-two taxa are identified as formerly described ones; of these, 16 are associated with a generic name different from the previous one, and four are ranked at a different taxonomic level. Twenty-four taxa are proposed as new and the rest likely represent undescribed species, but more, better preserved material is required in order to establish their identity and to name them. Of the 83 taxa considered, 17 are assigned to the genus Cochlis Röding, 1798, one belongs in Cryptonatica Dall, 1892, another belongs in Tanea Marwick, 1931, 11 are members of the genus Tectonatica Sacco, 1890, three are included in Ampullonatica Sacco, 1890, one belongs in Eunaticina Fischer, 1885, 20 are assigned to Euspira Agassiz in J. Sowerby, 1837, three belong in Neverita Risso, 1826, five belong in Payraudeautia Bucquoy, Dautzenberg & Dollfus,1883, two agree with the characters of Pliconacca Cossmann & Martin in Martin, 1914, four are members of Polinices Montfort, 1810, two belong in Sigatica Meyer & Aldrich, 1886, four belong in Sigaretotrerma Sacco, 1890, and nine have the characters of the genus Sinum Röding, 1798. All genera are discussed in terms of type species designation, distinctive characters and subfamilial affiliation (when different from the current one). The character analysis has shown that the measurable elements of the protoconch along with its microsculpture (if any) are diagnostic in many species of all subfamilies. The features of the outer surface of the calcareous operculum proved to be diagnostic in the Pliocene and Recent naticine species. In the present case, the operculum of only four Cochlis species is known, readily differentiating them from one another. The umbilical characters, i.e. umbilicus width and presence/absence and strength of inner spiral structures, proved to be of variable utility in identifying species. The inner umbilical characters are never species-diagnostic in the case of the naticine taxa, particularly those of Cochlis. The inner structures, primarily presence/absence, number and strength of cordlets or threads on the umbilical bottom, are more effective in distinguishing poliniceine taxa. The umbilical callus can be used diagnostically for a limited number of naticine and poliniceine taxa. The exterior sculpture of the teleoconch (absent in the naticine and in most poliniceine taxa) is well developed in all the sinine species. In the case of Sigaretotrema and Sinum, the sculptural characters proved to be relevant in species recognition. The color pattern is diagnostic in most of the taxa in which this character is preserved. The shell morphology and the apertural characters are relevant only in a few cases. In the absence of diagnostic elements, a combination of all characters can help in recognizing species. [ABSTRACT FROM AUTHOR]

The survival and reproductive success of hermit crabs is intrinsically linked to the quality of their domicile shells. Because damaged or eroded shells can result in greater predation, evaluating shell structure may aid our understanding of population dynamics. We assessed the structural attributes ofCerithium atratumshells through assessments of (a) density using a novel approach involving computed tomography and (b) tolerance to compressive force. Our goal was to investigate factors that may influence decision making in hermit crabs, specifically those that balance the degree of protection afforded by a shell (i.e. density and strength) with the energetic costs of carrying such resources. We compared the density and relative strength (i.e. using compression tests) of shells inhabited by live gastropods, hermit crabs (Pagurus criniticornis) and those found empty in the environment. Results failed to show any relationship between density and shell size, but there was a notable effect of shell density among treatment groups (gastropod/empty/hermit crab). There was also a predictable effect of shell size on maximum compressive force, which was consistent among occupants. Our results suggest that hermit crabs integrate multiple sources of information, selecting homes that while less dense (i.e. reducing the energy costs of carrying these resources), still offer sufficient resistance to compressive forces (e.g. such as those inflicted by shell-breaking predators). Lastly, we show that shell size generally reflects shell strength, thus explaining the motivation of hermit crabs to search for and indeed fight over the larger homes. [ABSTRACT FROM AUTHOR]

Cap-shaped gastropods are first identified in Upper Jurassic and Lower Cretaceous sections of northern East Siberia. They belong to three new genera of the subclass Pectinibranchia ( Boreioconus gen. nov., Nixepileolus gen. nov., and Taimyroconus gen. nov.), which are identified at the species level ( B. bojarkensis sp. nov., N. depressus sp. nov., T. zakharovi sp. nov.), and several species with the open nomenclature. The genus Taimyroconus attributed to the family Calyptraeidae is considered as an ancestral form of the genus Crepidula. The stratigraphic position of each taxon is determined for several sections. The facies confinement, habitat conditions, and ethology of defined genera are considered with the analysis of their geographic distribution. [ABSTRACT FROM AUTHOR]

Background: Mollusca is an extremely diverse animal phylum that includes the aculiferans (worm-like aplacophorans and eight-shelled polyplacophorans) and their sister group, the conchiferans, comprising monoplacophorans, bivalves (clams, mussels), gastropods (snails, slugs), scaphopods (tusk shells) and cephalopods (squids, octopuses). Studies on mollusks have revealed an overall number of 11 Hox genes in seven out of eight molluscan "class"-level taxa, but expression data of key developmental regulators such as homeotic genes are only available for three gastropod and two cephalopod species. These show that Hox genes are involved in the formation of specific features including shell, foot, funnel or tentacles and not in antero-posterior body plan patterning as in most other bilaterian animals. The role of Hox genes in non-conchiferan (i.e., aculiferan) mollusks remains entirely unknown. Results: Here we present the first data on the expression of seven Hox genes in apolyplacophoran mollusk, Acanthochitona crinita. In A. crinita the Hox genes Acr-Hox1-5, Hox7 and Post2 are expressed in a co-linear pattern along the antero-posterior axis, but not in molluscan-specific features such as the shell or the foot. The expression pattern is restricted to the post-trochal region and the transcripts are present in ecto-, endo- and mesodermal cell layers. Contrary to the situation in gastropods and cephalopods, we did neither find Hox gene expression in distinct neural subsets of A. crinita, nor in its developing shell plates. Conclusions: Our analysis and comparison with other lophotrochozoans indicate that the basal role of Hox genes is in antero-posterior axis patterning in mollusks, similar to the vast majority of bilaterian animals, and that this role has been conserved in polyplacophorans, while co-option into patterning of evolutionary novelties emerged either at the base of Conchifera or independently in gastropods and cephalopods. These morphological innovations most likely contributed to the evolutionary success of its representatives, as exemplified by, e.g., the wide ecological range and species richness of gastropods. [ABSTRACT FROM AUTHOR]

The apple snail Pomacea maculata is a recent introduction to Florida from its native range in South America. Little is known about the growth characteristics of apple snails. We measured δ18Oaragonite values along the shell growth axis of the non-native, aquatic pulmonate gastropod, Pomacea maculata, to determine its life span and seasonal growth pattern in Florida. Age, growth rate, and season of growth of P. maculata were determined from seasonal temperature fluctuations, inferred from δ18O values measured on aragonite drilled along the shell whorl. Eight of the 22 P. maculata lived less than one year, ten slightly longer than one year, and one into its third year. Three snails yielded indeterminate results. Snails from lakes Tulane and Verona deposited the majority of carbonate during late fall/early winter, whereas growth in Newnans Lake was divided across the seasons. Among specimens taken alive, and for which time of death was known, there were offsets along the shell margin with respect to δ18O values predicted from δ18Olake-water and temperature. The δ18Oaragonite of snails raised in temperature-controlled settings, however, was in close agreement with calculated empirical values. Isotopic offsets along the growth margin are probably a consequence of diminished carbonate deposition with increased specimen age. [ABSTRACT FROM AUTHOR]

Molluscan assemblages inhabiting subtidal soft bottoms in the northwestern Alboran Sea were studied to analyse temporal changes in structure and composition. A total of 117 samples were collected seasonally using a small rock dredge at 10 sampling stations, yielding 210 mollucan species. The assemblages occurring on the different soft bottoms were well-sorted fine sands assemblage (SFBC), mixed coarse sands assemblage (MX), muddy bioclastic sands assemblage (DE) and coastal bioclastic sands assemblage (DC), and all displayed high species richness values throughout the year. Different seasonal dynamics were observed and ecological indices were influenced by dominant species, especially the bivalveSpisula subtruncataat the shallow stations and the gastropodsCalyptraea chinensisandNassarius reticulatusat the deeper stations. SFBC displayed maximum abundance (N), species richness (S) and Shannon–Wiener diversity (H′) in autumn, DE and MX displayed maximum N and S in spring but maximum H′ in autumn (DE) and winter (MX), and finally DC displayed stable values of ecological indices throughout the year with minima in spring. Seasonal changes in the deep assemblages (25 m) were not significant and therefore less acute than those of shallower ones (5, 15 m), probably due to a lower influence of the environmental conditions and a higher habitat complexity. Seasonal patterns were somewhat different from those observed in more northern areas of Europe, where maximum abundance and species richness is usually concentrated at the end of summer. This original information will provide a baseline to understand the dynamics of benthic communities in this area. [ABSTRACT FROM PUBLISHER]

The concentrations of Cd, Cu, Pb, Fe, Ni and Zn were determined in the different parts of the soft tissues (foot, cephalic tentacle, mantle, muscle, gill, digestive caecum and remaining soft tissues) and three parts of hard tissues or shells (anterior shell, middle shell and posterior shell) of the mud-flat snail Telescopium telescopium collected from Sepang Besar River. From the cluster analysis, the dendrogram shows that the three parts of the shells are clustered separately from the different parts of the soft tissues, indicating different mechanisms and strategies of metal accumulation and regulation of heavy metals in the shells from the different soft tissues. Among the different soft tissues, the dendrogram also shows that the digestive caecum is clustered differently from other soft tissues, indicating that this organ is distinctly high in metal accumulation and this may probably suggest a different route of metal sequestration from the rest of the soft tissues. The metal distribution found in the different soft tissues of T. telescopium is an important knowledge in establishing this mud-flat gastropod as a promising biomonitor of metal contamination and bioavailability for the intertidal area of Peninsular Malaysia. [ABSTRACT FROM AUTHOR]

The Mobile River Basin is a hotspot of molluscan endemism, but anthropogenic activities have caused at least 47 molluscan extinctions, 37 of which were gastropods, in the last century. Nine of these suspected extinctions were in the freshwater gastropod genus Leptoxis (Cerithioidea: Pleuroceridae). Leptoxis compacta, a Cahaba River endemic, has not been collected for .70 years and was formally declared extinct in 2000. Such gastropod extinctions underscore the imperilment of freshwater resources and the current biodiversity crisis in the Mobile River Basin. During a May 2011 gastropod survey of the Cahaba River in central Alabama, USA, L. compacta was rediscovered. The identification of snails collected was confirmed through conchological comparisons to the L. compacta lectotype, museum records, and radulae morphology of historically collected L. compacta. Through observations of L. compacta in captivity, we document for the first time that the species lays eggs in short, single lines. Leptoxis compacta is restricted to a single location in the Cahaba River, and is highly susceptible to a single catastrophic extinction event. As such, the species deserves immediate conservation attention. Artificial propagation and reintroduction of L. compacta into its native range may be a viable recovery strategy to prevent extinction from a single perturbation event. [ABSTRACT FROM AUTHOR]

Among the diverse patterns of energy allocation to the offspring of gastropods, the presence of egg capsules to protect embryos is common. Females of the edible snail Zidona dufresnei attach egg capsules to hard substrates in shallow Argentine Patagonian waters (40°45′S, 64°56′W) during spring-summer. Embryonic development takes about 30 days at 22°C. In this study, three likely capsule predator species and the marks left by each on egg capsule walls were identified in laboratory experiments in February 2010. Abundances of predators and egg capsules with evidence of predation were assessed in the field in the summers of 2010 and 2011. Under laboratory conditions ( N = 10 replicates per treatment and control), the predation rate by the chiton Chaetopleura isabellei was the highest (up to 90%), followed by the gastropod Tegula patagonica and the crab Neohelice granulata (~20% each). Nearly 60% of 41 capsules found in the field showed signs of predation. According to the marks identified in the laboratory, C. isabellei was responsible for 79% of this predation, and T. patagonica for the rest. Predation appears to be important during the encapsulated early life and could be an agent for selecting for resistant capsule walls and a relatively shorter development time. [ABSTRACT FROM AUTHOR]

Abstract: Numerous large landslide deposits occur in the Tien Shan, a tectonically active intraplate orogen in Central Asia. Yet their significance in Quaternary landscape evolution and natural hazard assessment remains unresolved due to the lack of "absolute" age constraints. Here we present the first 10Be exposure ages for three prominent (>107 m3) bedrock landslides that blocked major rivers and formed lakes, two of which subsequently breached, in the northern Kyrgyz Tien Shan. Three 10Be ages reveal that one landslide in the Alamyedin River occurred at 11–15ka, which is consistent with two 14C ages of gastropod shells from reworked loess capping the landslide. One large landslide in Aksu River is among the oldest documented in semi-arid continental interiors, with a 10Be age of 63–67ka. The Ukok River landslide deposit(s) yielded variable 10Be ages, which may result from multiple landslides, and inheritance of 10Be. Two 10Be ages of 8.2 and 5.9ka suggest that one major landslide occurred in the early to mid-Holocene, followed by at least one other event between 1.5 and 0.4ka. Judging from the regional glacial chronology, all three landslides have occurred between major regional glacial advances. Whereas Alamyedin and Ukok can be considered as postglacial in this context, Aksu is of interglacial age. None of the landslide deposits show traces of glacial erosion, hence their locations and 10Be ages mark maximum extents and minimum ages of glacial advances, respectively. Using toe-to-headwall altitude ratios of 0.4–0.5, we reconstruct minimum equilibrium-line altitudes that exceed previous estimates by as much as 400m along the moister northern fringe of the Tien Shan. Our data show that deposits from large landslides can provide valuable spatio-temporal constraints for glacial advances in landscapes where moraines and glacial deposits have low preservation potential. [Copyright &y& Elsevier]

Mate searching often involves chemical cues and is a key process in determining fitness in most sexually reproducing animals. Effective mate-searching strategies are, therefore, essential for individuals to avoid wasting resources as a result of misrecognition of mating partners. Marine snails in the genus Littoraria are among the most successful molluscan groups that live closely associated with mangroves. Their population densities are often low, and finding a mate within the complex three-dimensional habitat of tree leaves, branches and trunks requires an effective searching strategy. We tested whether males of L. ardouiniana and L. melanostoma located females by following their mucus trails. In the laboratory, male tracker snails followed mucus trails laid by conspecific female marker snails at a higher intensity compared with other marker–tracker sex combinations in the mating season, but not in the nonmating season, and this was more pronounced in L. ardouiniana. Male trackers did not move faster when following the trails of conspecific female markers compared with other sex combinations; however, tracker snails moved faster in the mating than in the nonmating season, although this might be related to temperature. In both species, males tracked females regardless of trail complexity, and the majority of male trackers were able to detect the direction (polarity) of the trails of conspecific females. Together with previous studies on rocky shore Littorina species, these findings suggest that sex pheromones are incorporated into mucus trails to facilitate the reproductive success of these snails. Mucus trail following is, therefore, an adaptive mate-searching strategy in intertidal gastropod molluscs, and potentially in other gastropod groups in which trail-following behaviour is prevalent. [Copyright &y& Elsevier]

Numerous studies indicate that the behavioral responses of prey to the presence of predators can have an important role in structuring assemblages through trait-mediated indirect interactions. Few studies, however, have addressed how relative susceptibility to predation influences such interactions. Here we examine the effect of chemical cues from the common shore crab Carcinus maenas on the foraging behavior of two common intertidal gastropod molluscs. Of the two model consumers studied, Littorina littorea is morphologically more vulnerable to crab predation than Gibbula umbilicalis, and it exhibited greater competitive ability in the absence of predation threat. However, Littorina demonstrated a greater antipredator response when experimentally exposed to predation cues, resulting in a lower level of foraging. This reversed the competitive interaction, allowing Gibbula substantially increased access to shared resources. Our results demonstrate that the susceptibility of consumers to predation can influence species interactions, and suggest that inter-specific differences in trait-mediated indirect interactions are another mechanism through which non-consumptive predator effects may influence trophic interactions. [ABSTRACT FROM AUTHOR]

Cellulase and hemicellulases (mannanase, xylanase, xyloglucanase, and licheninase) activities were measured in the extracts of 18 species of macrobenthos (an oligochaete, two polychaetes, two decapods, one amphipod, three bivalves, and nine gastropods) to check the relevance of macrobenthos to the breakdown process of hard-degradable carbohydrates derived from terrestrial plants. As a result, these enzyme activities were detected in all of the extracts of macrobenthos except for Tubificidae sp. High cellulase activities were detected in the extracts of the decapods ( Neocaridina denticulate denticulate, Caridina multidentata) and the gastropods ( Semisulcospira libertina, S. reiniana, Physa acuta, Terebralia palustris). However, only weak activities were detected in the polychaetes ( Perinereis nuntia, P. aibuhitensis) and the bivalve ( Ruditapes philippinarum). High mannanase and licheninase activities were detected in two decapod species ( N. denticulate, C. multidentata), while high xylanase activities were seen in the gastropods ( S. libertina, S. reiniana). High xyloglucanase activities were noted in the gastropod ( T. palustris). These facts suggest that the activities of different types of hemicellulase were distributed rather unevenly among the macrobenthos. The present paper is the first to report the widespread distribution of cellulase and hemicellulase activities among ecologically important aquatic invertebrates, and the possible relevance of these species in the breakdown process of plant-derived hard-degradable carbohydrates. [ABSTRACT FROM AUTHOR]

Abstract: Electron backscatter diffraction (EBSD) is a microscopy technique that reveals in situ crystallographic information. Currently, it is widely used for the characterization of geological materials and in studies of biomineralization. Here, we analyze high resolution EBSD data from biogenic calcite in two mollusk taxa, Concholepas and Haliotis, previously used in the understanding of complex biomineralization and paleoenvironmental studies. Results indicate that Concholepas has less ordered prisms than in Haliotis, and that in Concholepas the level of order is not homogenous in different areas of the shell. Overall, the usefulness of data integration obtained from diffraction intensity and crystallographic orientation maps, and corresponding pole figures, is discussed as well as its application to similar studies. [ABSTRACT FROM AUTHOR]

Abstract: To better understand the cascade of molecular reactions leading to delayed development and mortality of early life stages of marine intertidal gastropods, in response to temperature and salinity changes associated with climate change, three biomarkers: total antioxidant capacity, lipid peroxidation and lysosomal stability were investigated on hatched larvae. Encapsulated embryos of three marine gastropod species (Bembicium nanum, Siphonaria denticulata and Dolabrifera brazieri), which have already proven responsive to thermal and osmotic variations, were exposed to six combinations of temperature (22°C and 30°C) and salinity (25‰, 35‰ and 45‰) until the larvae hatched. Time to hatching was affected by salinity and temperature in all three species. High salinity (45‰) generally retarded the hatching process although the response was species-specific for temperature. Total antioxidant capacity and lipid peroxidation were also highly species-specific with the general trend showing that these biomarkers were adversely affected by high temperature (30°C) at salinities of 25‰ and 45‰. Bembicium nanum lysosomal destabilisation increased significantly with an increase in temperature and salinity (30°C and 45‰) and this was associated with delayed development and increased mortality. Investigations on the additional biomarker, lysosomal stability, gave a clearer picture of the numerous and complex molecular and cellular mechanisms leading to mortality and underdevelopment in response to environmental stress for this species. As few differences were observed in the enzymatic biomarkers total antioxidant capacity and lipid peroxidation between hatched larvae and the previously investigated encapsulated embryo response to thermal and osmotic stress, it is suggested that further studies could be undertaken using embryos encapsulated in egg masses, as it is less time consuming than working on hatched larvae. [Copyright &y& Elsevier]

Abstract: Marine larvae that experience some sub-lethal stresses can show effects from those stresses after metamorphosis, even when they seem to recover from those stresses before metamorphosis. In this study we investigated the short and long-term effects of exposing the larvae of three calyptraeid gastropods (Crepidula fornicata, Crepidula onyx, and Crepipatella fecunda) to temporary reductions in salinity. Larvae of all three species showed slower larval growth rates, longer time to metamorphic competence, and substantial mortality after being stressed in seawater at salinities of 10, 15, and 20 for less than 48h. Larval tolerance to low salinities varied widely within and among species, but longer stresses at lower salinities were generally more harmful to larvae. However, larvae in nearly all experiments that were able to metamorphose survived and grew normally as juveniles; there were no documented “latent effects.” For all three species, starving larvae in full-strength seawater was not as harmful as exposing larvae to low salinity stress, indicating that detrimental effects on larvae were caused by the salinity stress per se, rather than by an indirect effect of salinity stress on feeding. C. fornicata that were stressed with low salinity as juveniles were more tolerant of the stress than larvae: all stressed juveniles lived and showed reduced growth rates for no more than 3days. Our data suggest that even though reduced salinity is clearly stressful to the larvae of these 3 gastropod species, metamorphosis seems to generally provide individuals with a fresh start. [ABSTRACT FROM AUTHOR]

Abstract: In the Baltic Sea, increased populations of the three-spined stickleback are invading the coastal zone in summer, following declines in large predatory fish such as cod, pike, and perch. Here, we explore the consequences of such a meso-predator release on a near-natural scale, by manipulating stickleback densities in four large 600m2 enclosures: two ‘removal’ and two ‘addition’ enclosures. Higher densities of stickleback resulted in a three times higher recruitment of ephemeral green macroalgae. At the same time we found higher abundances of the dominating invertebrate grazers with lower stickleback densities: higher numbers of both amphipods and smaller gastropods were found in one stickleback ‘removal’ enclosure and higher numbers of large gastropods occurred in the other ‘removal’ enclosure. Grazer abundances also depended on the macrophyte species that dominated the enclosures. Nutrient enrichment had no statistically significant effect on algal recruitment, although the mean number of algal recruits was almost doubled under enriched conditions. Our results indicate that a meso-predator release of stickleback may dramatically shift coastal food web constitution towards increased abundances of ephemeral macroalgae through a trophic cascade. [ABSTRACT FROM AUTHOR]

Abstract: The marine subtidal volutid snail Adelomelon beckii was studied in order to obtain their population dynamics, particularly on growth, age, mortality and production. Stable oxygen isotope ratios confirmed semiannual formation of internal growth marks. A von Bertalanffy growth model fitted 308 size-at-age data pairs. A. beckii potential lifespan in Mar del Plata (Argentina) region is 29years, being rather long lived compared to other large gastropods. Total mortality Z and natural mortality M were calculated to be 0.210y−1 and 0.081y−1 respectively. Fishing mortality F amounts to 0.129y−1 corresponding to an exploitation rate E of 0.614, a value much beyond the optimum rate of 0.427. The current exploitation regime will be unsustainable in the long run unless a proper management approach establishes. [Copyright &y& Elsevier]

Reliable population DNA molecular markers are difficult to develop for molluscs, the reasons for which are largely unknown. Identical protocols for microsatellite marker development were implemented in three gastropods. Success rates were lower for Gibbula cineraria compared to Littorina littorea and L. saxatilis. Comparative genomic analysis of 47.2 kb of microsatellite containing sequences (MCS) revealed a high incidence of cryptic repetitive DNA in their flanking regions. The majority of these were novel, and could be grouped into DNA families based upon sequence similarities. Significant inter-specific variation in abundance of cryptic repetitive DNA and DNA families was observed. Repbase scans show that a large proportion of cryptic repetitive DNA was identified as transposable elements (TEs). We argue that a large number of TEs and their transpositional activity may be linked to differential rates of DNA multiplication and recombination. This is likely to be an important factor explaining inter-specific variation in genome stability and hence microsatellite marker development success rates. Gastropods also differed significantly in the type of TEs classes (autonomous vs non-autonomous) observed. We propose that dissimilar transpositional mechanisms differentiate the TE classes in terms of their propensity for transposition, fixation and/or silencing. Consequently, the phylogenetic conservation of non-autonomous TEs, such as CvA, suggests that dispersal of these elements may have behaved as microsatellite-inducing elements. Results seem to indicate that, compared to autonomous, non-autonomous TEs maybe have a more active role in genome rearrangement processes. The implications of the findings for genomic rearrangement, stability and marker development are discussed. [ABSTRACT FROM AUTHOR]

Abstract: Around 130 publications reporting studies on radionuclide transfer to freshwater biota species conducted in the former USSR were reviewed to provide the concentration ratio values. None of these studies were available up to now in the English language reviews or publications. The values derived have been compared with the CR values used for freshwater systems in the International reviews. For some radionuclides reviewed in this paper, the data are in good agreement with the mean CR values presented earlier, however for some of them, in particular, for 241Am (bivalve molluscs, gastropods and pelagic fish), 60Co (gastropods, benthic fish and insect larvae), 90Sr and 137Cs (benthic fish and zooplankton), the mean values given here are substantially different from those presented earlier. The data reported in this paper for thirty five radionuclides and eleven groups of freshwater species markedly improve the extent of available data for evaluation of radiation impact on freshwater species. [Copyright &y& Elsevier]

Posilović, H., & Bajraktarević, Z. 2010: Functional morphological analysis of evolution of ribbing in pliocene viviparid shells from Croatia. Lethaia, 10.1111/j.1502-3931.2009.00209.x. This paper provides a functional analysis of Pliocene freshwater gastropods from the phylogenetic lineage of Viviparus neumayri to Viviparus ornatus. On this section of the phylogenetic line, it is possible to follow the continuous evolution of the shell ornamentation (shouldering and rib formation) from ancestral V. neumayri with smooth shell to V. ornatus with spiral ribs. The shell morphology and possible structural function of rib development is discussed from the analytical point of view, but also by Finite Element Modelling. Spiral rib development in the viviparids is not correlated with shell thickening, but rather with strengthening of the shell is achieved through development of spiral ribs, with direct biomechanical and evoloutionary significance. □ Croatia, functional morphology, gastropod shell evolution, Pliocene, viviparid evolution. [ABSTRACT FROM AUTHOR]

Many eurythermal organisms alter composition of their membranes to counter perturbing effects of environmental temperature variation on membrane fluidity, a process known as homeoviscous adaptation. Marine intertidal gastropods experience uniquely large thermal excursions that challenge the functional integrity of their membranes on tidal and seasonal timescales. This study measured and compared membrane fluidity in marine intertidal snail species under three scenarios: (1) laboratory thermal acclimation, (2) thermal acclimatization during a hot midday low tide, and (3) thermal acclimatization across the vertical intertidal zone gradient in temperature. For each scenario, we used fluorescence polarization of the membrane probe DPH to measure membrane fluidity in individual samples of gill and mantle tissue. A four-week thermal acclimation of Tegula funebralis to 5, 15, and 25°C did not induce differences in membrane fluidity. Littorina keenae sampled from two thermal microhabitats at the beginning and end of a hot midday low tide exhibited no significant differences in membrane fluidity, either as a function of time of day or as a function of thermal microhabitat, despite changes in body temperature up to 24°C within 8 h. Membrane fluidities of a diverse group of snails collected from high, middle, and low vertical regions of the intertidal zone varied among species but did not correlate with thermal microhabitat. Our data suggest intertidal gastropod snails do not exhibit homeoviscous adaptation of gill and mantle membranes. We discuss possible alternatives for how these organisms counter thermal excursions characteristic of the marine intertidal zone. [ABSTRACT FROM AUTHOR]

Community assembly rules theory attempt to understand the processes that determine the composition of local communities from a regional species pool. Nestedness and negative co-occurrence are two of the most commonly reported meta-community patterns, but almost exclusively from terrestrial and freshwater ecosystems. Here we analyzed the structure of species coexistence in six datasets containing presence/absence data for 120 marine benthic gastropod species in 249 sampling units on the Uruguayan continental shelf and Río de la Plata estuary. The ecological features of this system, such as the idiosyncratic nature of the biogeographic and oceanographic realms, are clearly different from those observed in other systems previously targeted by studies on coexistence structure. Community patterns were evaluated using null models and four structure indices. The existence of patterns in community assembly, and in particular segregated co-occurrence, was verified only when analyzing the number of checkerboard units (CH index). This indicates more mutually exclusive species pairs than expected by chance. Nestedness, on the other hand, was not detected in any dataset. Storage and rescue effects related to overall high immigration and low local extinction rates are plausible mechanisms to account for the general pattern of random species coexistence, while the segregated co-occurrence pattern depicted by the CH index may be related to differential habitat requirements within species pairs. Our study highlights the importance of analyzing metacommunity structures in alternative biological, environmental, and historical contexts in order to advance on the construction of a general ecological theory, relating patterns with the processes dominating in particular ecosystems. [ABSTRACT FROM AUTHOR]

In the frame of investigating the flora and fauna of Rodna Mountains National Park, this paper aims to supplement the data on the fauna of terrestrial gastropods of the area. The study analyzes the terrestrial gastropod fauna of Repede River Valley in the Northern area of Rodna Mountains National Park. Qualitative samples were taken from 7 locations between Vişeu River and the confluence of Repede River with Buhăescu. After analyzing the collected material, 33 species were identified. In each sampling station were identified 5 to 17 terrestrial gastropod species, the highest value was recorded in the town of Borşa. Among the species the more common are Monachoides vicinus, Faustina faustina and Trichia bielzi. [ABSTRACT FROM AUTHOR]

The chemical composition and body proportions of Achatina fulica (Bowdich), Achatina achatina (Linné) and Archachatina ventricosa (Gould) fed a concentrated diet were investigated and compared with wild A. fulica, A. achatina and Arch. ventricosa. Wild and artificially reared snail shell proportion were 42.09 and 46.91%; 47.20 and 52.96%; 48.02 and 51.96% of the whole body, respectively, for A. fulica, A. achatina and Arch. ventricosa. The pedal mass proportion was 41.36 and 36.66%; 27.80 and 26.62% than 36.59 and 32.71%, respectively, for wild and reared A. fulica, A. achatina and Arch. ventricosa. The pedal mass mean energy, dry matter, proteins, lipid and mineral matter content were 53.21cal/100g; 12.86% by weight of deshelled snails; 63.98/ DM (% of dry matter); 15.80/DM and 8.96/DM in A. achatina. For A. fulica pedal mass aver age energy, dry matter, proteins and mineral matter content were 47.82 cal/100 g; 13.63% by weight of deshelled snails; 58.94/DM and 14.92/DM. Arch. ventricosa pedal mass mean energy, dry matter, proteins, lipid and mineral matter content were 50.32 cal/100g; 14.19% in weight of deshelled snails; 66.36/DM; 13.43/DM and 10.25/DM. The protein contents differed slightly between artificially reared and wild snails. [ABSTRACT FROM AUTHOR]

Background: A robust phylogenetic hypothesis of euthyneuran gastropods, as a basis to reconstructing their evolutionary history, is still hindered by several groups of aberrant, more or less worm-like slugs with unclear phylogenetic relationships. As a traditional "order" in the Opisthobranchia, the Acochlidia have a long history of controversial placements, among others influenced by convergent adaptation to the mainly meiofaunal habitats. The present study includes six out of seven acochlidian families in a comprehensive euthyneuran taxon sampling with special focus on minute, aberrant slugs. Since there is no fossil record of tiny, shell-less gastropods, a molecular clock was used to estimate divergence times within Euthyneura. Results: Our multi-locus molecular study confirms Acochlidia in a pulmonate relationship, as sister to Eupulmonata. Previous hypotheses of opisthobranch relations, or of a common origin with other meiofaunal Euthyneura, are clearly rejected. The enigmatic amphibious and insectivorous Aitengidae incerta sedis clusters within Acochlidia, as sister to meiofaunal and brackish Pseudunelidae and limnic Acochlidiidae. Euthyneura, Opisthobranchia and Pulmonata as traditionally defined are non-monophyletic. A relaxed molecular clock approach indicates a late Palaeozoic diversification of Euthyneura and a Mesozoic origin of the major euthyneuran diversity, including Acochlidia. Conclusions: The present study shows that the inclusion of small, enigmatic groups is necessary to solve deeplevel phylogenetic relationships, and underlines that "pulmonate" and "opisthobranch" phylogeny, respectively, cannot be solved independently from each other. Our phylogenetic hypothesis requires reinvestigation of the traditional classification of Euthyneura: morphological synapomorphies of the traditionally defined Pulmonata and Opisthobranchia are evaluated in light of the presented phylogeny, and a redefinition of major groups is proposed. It is demonstrated that the invasion of the meiofaunal habitat has occurred several times independently in various euthyneuran taxa, leading to convergent adaptations previously misinterpreted as synapomorphies. The inclusion of Acochlidia extends the structural and biological diversity in pulmonates, presenting a remarkable flexibility concerning habitat choice. [ABSTRACT FROM AUTHOR]

The comparative genetic structure of hosts and their parasites has important implications for their coevolution, but has been investigated in relatively few systems. In this study, we analysed the genetic structure and diversity of the New Zealand intertidal snail Zeacumantus subcarinatus ( n = 330) and two of its trematode parasites, Maritrema novaezealandensis ( n = 269) and Philophthalmus sp. ( n = 246), using cytochrome c oxidase subunit I gene ( COI) sequences. Snails and trematodes were examined from 11 collection sites representing three regions on the South Island of New Zealand. Zeacumantus subcarinatus displayed low genetic diversity per geographic locality, strong genetic structure following an isolation by distance pattern, and low migration rates at the scale of the study. In contrast, M. novaezealandensis possessed high genetic diversity, genetic homogeneity among collection sites and high migration rates. Genetic diversity and migration rates were typically lower for Philophthalmus sp. compared to M. novaezealandensis and it displayed weak to moderate genetic structure. The observed patterns likely result from the limited dispersal ability of the direct developing snail and the utilization of bird definitive hosts by the trematodes. In addition, snails may occasionally experience long-distance dispersal. Discrepancies between trematode species may result from differences in their effective population sizes and/or life history traits. [ABSTRACT FROM AUTHOR]

The distribution of a phenotypic state is often discontinuous and dispersed. An example of such a distribution can be found in the shell shapes of terrestrial gastropods, which exhibit a bimodal distribution whereby species possess either a tall shell or a flat shell. Here we propose a simple model to test the hypothesis that the bimodal distribution relates to the optimum shape for shell balance on the substrates. This model calculates the theoretical shell balance by moment and obtains empirical distribution of shell shape by compiling published data and performing a new analysis. The solution of the model supports one part of the hypothesis, showing that a low-spired shell is the best balanced and is better suited for locomotion on horizontal surface. Additionally, the model shows that both high- and low-spired shells are well balanced and suited on vertical surfaces. The shell with a spire index (shell height divided by diameter) of 1.4 is the least well balanced as a whole. Thus, spire index is expected to show a bimodal distribution with a valley at 1.4. This expectation was supported by empirical distribution of a spire index, suggesting that the bimodality of shell shape in terrestrial gastropods is related to shell balance. [ABSTRACT FROM AUTHOR]

Encapsulation is a common strategy among marine invertebrate species. It has been shown that oxygen and food availability independently constrain embryo development during intracapsular development. However, it is unclear how embryos of species with different feeding strategies perceive these two constraints when operating jointly. In the present study, we examined the relative importance of dissolved albumen, as a food source, oxygen condition and their interaction on embryonic growth and the survival of two calyptraeid species, Crepidula coquimbensis and Crepidula fornicata, exhibiting different embryo feeding behaviours (i.e. presence vs absence of intracapsular cannibalism). Two oxygen condition treatments (normoxia and hypoxia) and three albumen concentrations (0, 1 and 2mg I-1) were studied. In addition, albumen intake by embryos was observed using fluorescence microscopy. Our study shows that embryos of both species incorporated dissolved albumen but used a different set of embryonic organs. We observed that embryo growth rates in C. coquimbensis were negatively affected only by hypoxic conditions. Conversely, a combination of low albumen concentration and oxygen availability slowed embryo growth in C. fornicata. These findings suggest that oxygen availability is a limiting factor for the normal embryo development of encapsulated gastropod species, regardless of feeding behaviour or developmental mode. By contrast, the effect of dissolved albumen as an alternative food source on embryo performance may depend on the feeding strategy of the embryos. [ABSTRACT FROM AUTHOR]

Alginate lyase (EC 4.2.2.3) is an enzyme that splits glycosyl linkages of alginate chain via β-elimination, producing unsaturated oligoalginates. This enzyme is widely distributed in herbivorous marine mollusks, brown algae, and marine and soil bacteria. In the present study, we determined the general properties and partial amino acid sequences of alginate lyases from three Archeogastropoda, i.e., Haliotis discus hannai, H. iris, and Omphalius rusticus, and one Mesogastropoda, i.e., Littorina brevicula, in order to enrich the information about functional and structural diversity in gastropod alginate lyases. The alginate lyases were extracted from hepatopancreas of these animals and purified by ammonium sulfate fractionation followed by conventional column chromatography. Single alginate lyases with molecular masses of approximately 28, 34, and 34 kDa were isolated from H. discus, H. iris, and O. rusticus, respectively. While three alginate lyases with molecular masses of 35, 32, and 28 kDa were isolated from L. brevicula. These enzymes were identified as poly(M) lyase (EC 4.2.2.3) since they preferably degraded poly(M)-rich substrate. Western blot analysis using an antiserum raised against H. discus enzyme suggested that H. iris, and O. rusticus enzymes shared similar primary/higher-order structure with H. discus enzyme, but the L. brevicula enzymes did not. H. discus, H. iris, and O. rusticus enzymes were classified to polysaccharide-lyase family-14 by the analysis of partial amino acid sequences, while the L. brevicula enzymes were not. [ABSTRACT FROM AUTHOR]

In many gastropods, a serotonin-like immunoreactive axon plexus lies over ciliary cells on the pedal sole. The origin and function of axons in this plexus is uncertain. By using serotonin antibodies in the direct-developing embryo of the pond snail, the axons that initially form this plexus were traced from seven large neurons in each pedal ganglion. Soon after metamorphosis begins, the first immunoreactive pedal ganglion neuron sends multiple branched neurites to lie directly over pedal sole ciliary cells. By 70% of the 11 days required for hatching, axons from the seven neuron pairs form a plexus over ciliary cells in the whole sole. The axon from each of the seven neurons is guided to a specific area of the pedal plexus where ciliary cells are developing. Axons from two pairs of these neurons, which form the pedal plexus in the posterior part of the foot, are in the unpaired nerve that comes from the pedal ganglia ventral commissure. It is likely that these two developing neuron pairs are homologs of the two neuron pairs in Lymnaea stagnalis that have axons in this ventral commissure nerve. Identification of these neurons and the other five neuron pairs with axons in the pedal plexus will provide a basis for future studies of the relation between the plexus and pedal ciliary locomotion. [ABSTRACT FROM AUTHOR]

Intertidal mudflats in Bahrain provide essential feeding grounds for a good number of shorebirds. The spatial distribution of soft-sediment macrobenthic invertebrate assemblages inhabiting a mudflat designated as a natural marine protected area was investigated to characterize shorebird food supplies. Molluscs accounted for 88% of the total macroinvertebrates community, reflecting a dominance of gastropod grazers. Six species of wading birds were recorded feeding in the protected area. Bird disturbance associated with human recreational activities that may interfere with the conservational benefits of this protected area was explored. This study highlighted the crucial need for management plans for protected areas and for further research concerning bird disturbance. [ABSTRACT FROM AUTHOR]

The enigmatic deuterostome Xenoturbella does ubiquitously contain exogenous nucleic acids. This has been used in several papers as proof of selective feeding by Xenoturbella on nuculid bivalves. However, their feeding biology is unknown and exogenous nucleic acids might not originate from their main nutrient source. I have examined the possible pathways of nutrient uptake. The animals neither took up cells nor dissolved dyes through the 'mouth'. Instead, they possessed extensive pinocytosis through the epidermis. Therefore, it is probable that the main source of nutrients is dissolved organic matter uptaken through the epidermis. This does not exclude that phagocytosis in the gastrodermis does occur, e.g. due to direct expose of the gastrodermis during asexual reproduction. The ubiquitously present exogenous nucleic acids in Xenoturbella probably do originate from such events and not from their main food source. [ABSTRACT FROM AUTHOR]