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The size and shape of red blood cells (RBCs) provide key information on life-history strategies in vertebrates. However, little is known about how RBC shape evolved in response to environmental factors, body size and the role of evolutionary rate. Here, we analysed RBC morphometrics in a set of Teleostei (bony fishes) and Elasmobranchii (sharks and rays) species testing the hypothesis that phylogenetic relationship explains species occupation of morphospace. We collected data on cell and nucleus area and volume, nucleus:cytoplasm ratio and shape factor for 65 species belonging to 28 orders. Then, we built phylomorphospaces separately for bony fish and sharks and rays. To test whether phylogenetic relationships predicted phenotypic similarity, we calculated multivariate phylogenetic signal. We also estimated the evolutionary rate of RBC shape for each node and tip using ridge regression. Finally, we tested whether habitat and body size influenced RBC shape using a PGLS. We found a significant phylogenetic signal in RBC shape for bony fish, but not sharks and rays. Saltwater teleost species were more clustered than freshwater ones in the phylomorphospace, suggesting clade disparity. Accordingly, the rate of evolution was highly heterogeneous, with significant decrease in Acanthopterygii. Neither habitat nor body size influenced RBC shape. In conclusion, RBC shape seems to have evolved in fishes in response to multiple selective pressures independent of life-history characters.

Vertebrates have four visual cone opsin classes that, together with a light-sensitive chromophore, provide sensitivity from the ultraviolet to the red wavelengths of light. The rhodopsin-like 2 (RH2) opsin is sensitive to the centre blue-green part of the spectrum, which is the most prevalent light underwater. While various vertebrate groups such as mammals and sharks have lost theRH2gene, in teleost fishes this opsin has continued to proliferate. By investigating the genomes of 115 teleost species, we find thatRH2shows an extremely dynamic evolutionary history with repeated gene duplications, gene losses and gene conversion affecting entire orders, families and species. At least four ancestral duplications provided the substrate for today’sRH2diversity with duplications occurring in the common ancestors of Clupeocephala, Neoteleostei, and Acanthopterygii. Following these events,RH2has continued to duplicate both in tandem and during lineage specific genome duplications. However, it has also been lost many times over so that in the genomes of extant teleosts, we find between zero to eightRH2copies. Using retinal transcriptomes in a phylogenetic representative dataset of 30 species, we show thatRH2is expressed as the dominant green-sensitive opsin in almost all fish lineages. The exceptions are the Osteoglossomorpha (bony tongues and mooneyes) and several characin species that have lostRH2, and tarpons, other characins and gobies which do not or only lowly express the gene. These fishes instead express a green-shifted long-wavelength-sensitiveLWSopsin. Our study highlights the strength of using modern genomic tools within a comparative framework to elucidate the detailed evolutionary history of gene families.

To investigate chromosome evolution in fish species, we newly mapped 181 markers that allowed us to construct a yellowtail (Seriola quinqueradiata) radiation hybrid (RH) physical map with 1,713 DNA markers, which was far denser than a previous map, and we anchored the de novo assembled sequences onto the RH physical map. Finally, we mapped a total of 13,977 expressed sequence tags (ESTs) on a genome sequence assembly aligned with the physical map. Using the high-density physical map and anchored genome sequences, we accurately compared the yellowtail genome structure with the genome structures of five model fishes to identify characteristics of the yellowtail genome. Between yellowtail and Japanese medaka (Oryzias latipes), almost all regions of the chromosomes were conserved and some blocks comprising several markers were translocated. Using the genome information of the spotted gar (Lepisosteus oculatus) as a reference, we further documented syntenic relationships and chromosomal rearrangements that occurred during evolution in four other acanthopterygian species (Japanese medaka, zebrafish, spotted green pufferfish and three-spined stickleback). The evolutionary chromosome translocation frequency was 1.5-2-times higher in yellowtail than in medaka, pufferfish, and stickleback.

A new tilefish, Branchiostegus biendong, is described on the basis of three specimens (181–209 mm in standard length [SL]) collected from a local fish market of Quy Nhon on the South China Sea coast of central Vietnam. It can be distinguished from 17 congeners in having the following combination of characters: six diagonal scale rows exposed on cheek; cheek scales moderately large (diameter 2.2–2.5% SL); predorsal ridge black; cheek almost silver with an oval-shaped, yellow blotch along ventral margin of eye; dorsal fin translucent yellowish with narrow black margin overlapping stronger yellowish coloration dorsally; upper lobe of caudal fin with 5–6 yellow stripes and tip with black blotch; and lower lobe of caudal fin navy blue. A key to five species of Branchiostegus from Vietnamese waters is provided.

The presence of Aluterus monoceros (Linnaeus, 1758) in Mar del Plata, Argentina (38° S) was registered over 40 years ago. This new report extends its southernmost distribution limit to 39° S (Necochea: ~ 120 km). The presence of the species could be associated to the warm subtropical water derived from the Brazilian continental shelf. The hypothesis was tested with satellite images of the sea surface temperature recorded during the cruise the specimen was caught.

A total of 1,471 specimens of 16 species of flatfishes (Pleuronectiformes) were caught during 48 sampling campaigns between July 2005 and June 2007 at ten stations in Guanabara Bay, Rio de Janeiro, Brazil. Paralichthyidae was the dominant family, with Etropus crossotus as the dominant species. The outer stations, especially those on the western side of the lower estuary, were distinguished as a result of their higher abundance of flatfishes and number of species. The spatial distribution of E. crossotus and its population structure indicate that this species is an estuarine resident despite the apparent reduction in its area of occupation within the estuarine complex. Among the other species, nine were classified as marine stragglers (Achirus declivis, Bothus ocellatus, Cyclopsetta chittendeni, Etropus longimanus, Paralichthys orbignyanus, P. patagonicus, Syacium micrurum, Symphurus diomedeanus and Trinectes paulistanus) and three as estuarine opportunists (Bothus robinsi, Citharichthys macrops and Syacium papillosum); another three could not be classified due to the small number of captures or lack of previous data (S. tessellatus, A. lineatus and C. spilopterus). Resumo: Um total de 1.471 espécimes de 16 espécies de linguados (Pleuronectiformes) foram capturados durante 48 campanhas de amostragem entre julho de 2005 e junho de 2007 em dez estações na Baía de Guanabara, Rio de Janeiro, Brasil. Paralichthyidae foi a família dominante, com Etropus crossotus como a espécie dominante. As estações externas, especialmente aquelas no lado ocidental do baixo estuário, foram distinguidas como resultado de sua maior abundância de linguados e número de espécies. A distribuição espacial de E. crossotus e sua estrutura populacional indicam que esta espécie é uma residente estuarina, apesar da aparente redução em sua área de ocupação dentro do complexo estuarino. Dentre as outras espécies, nove foram classificadas como migrantes marinhos (Achirus declivis, Bothus ocellatus, Cyclopsetta chittendeni, Etropus longimanus, Paralichthys orbignyanus, P. patagonicus, Syacium micrurum, Symphurus diomedeanus e Trinectes paulistanus) e três como oportunistas estuarinos (Bothus robinsi, Citharichthys macrops e Syacium papillosum); outras três não puderam ser classificados devido ao pequeno número de capturas ou falta de dados prévios (S. tessellatus, A. lineatus e C. spilopterus).

While much of the functional work on suction feeding has involved members of Acanthopterygii, an earlier cypriniform radiation led to over 3200 species filling nearly every freshwater trophic niche. Within the great majority of acanthomorph clades that have been investigated suction feeding and the underlying morphology responsible for the generation of rapid suction have been largely conserved. This conserved feeding-apparatus is often associated with increasing the force experienced by the prey item, thus making a strike on elusive prey more effective. Cypriniforms' trophic anatomy is comprised of a number of novelties used for benthic feeding, which characterized early members of this clade. The modified cypriniform structure of the oral jaws represents a situation in which a particular type of suction feeding allowed for probing the benthos with a more functionally maneuverable anatomy. Requisite evolutionary modifications included origin and elongation of a median kinethmoid, duplications of certain divisions of the muscles of the adductor mandibulae, and origin of a dorsal, intra-buccal muscular palatal organ used in winnowing detritus. The elongated kinethmoid (coupled with modified adductor muscles) allowed for a type of premaxillary protrusion that decoupled the upper and lower jaws, enabled premaxillary protrusions with a closed mouth, and facilitated benthic feeding by increasing functional flexibility. The resultant flow of fluid generated by cypriniforms is also quite flexible, with multiple instances of peak flow in a single feeding event. This greatly modified morphology allowed for a degree of kinematic maneuverability not seen within most acanthomorphs. Later cypriniform radiations into piscivorous, insectivorous, or planktivorous feeding guilds were associated with shortening of the kinethmoid and with simplified morphology of the adductor, likely involving an emphasis on ram feeding. Although this suite of morphological novelties seemingly originated within the context of benthic feeding, with minimal modifications these anatomical features were later coopted during radiations into different functional niches.

Tetrahymena is a ciliated protozoan that can infect a wide range of fish species, although it is most commonly reported in guppies (Poecilia reticulata). The aim of this study was to compare the susceptibility to infection with Tetrahymena of five different ornamental fish species from two different super orders. The species examined were platy (Xiphophorus), molly (Poecilia sphenops) and angelfish (Pterophyllum scalare) of the Acanthopterygii super order (which also includes guppies) and goldfish (Carassius auratus auratus) and koi carp (Cyprinus carpio) of the Ostariophysi super order. These two super orders are phylogenetically distant from each other. Infection with Tetrahymena resulted in parasite invasion of internal organs, skin and muscle in all fish species. A relatively strong inflammatory response was observed in infected goldfish and koi, with negligible response in fish species of the Acanthopterygii super order. Guppies were the most susceptible to Tetrahymena infection, exhibiting a mortality rate of 87% and 100% in two separate experiments. A high mortality rate was also observed in platy (77%), while that of molly and angelfish was significantly lower (23% and 33%, respectively). Goldfish and koi carp were less susceptible to infection compared with guppies (24% and 59% mortality, respectively). Immunization studies revealed that the Tetrahymena are immunogenic, since infection of koi carp increased their Tetrahymena immobilization response by approximately three-fold at 3 weeks post infection, while immunization with Tetrahymena plus adjuvant increased their immobilization response by approximately 30-fold.

Analysis of maximum depth of occurrence of 11 952 marine fish species shows a global decrease in species number (N) with depth (x; m): log10 N = -0·000422x + 3·610000 (r(2) = 0·948). The rate of decrease is close to global estimates for change in pelagic and benthic biomass with depth (-0·000430), indicating that species richness of fishes may be limited by food energy availability in the deep sea. The slopes for the Classes Myxini (-0·000488) and Actinopterygii (-0·000413) follow this trend but Chondrichthyes decrease more rapidly (-0·000731) implying deficiency in ability to colonize the deep sea. Maximum depths attained are 2743, 4156 and 8370 m for Myxini, Chondrichthyes and Actinopterygii, respectively. Endemic species occur in abundance at 7-7800 m depth in hadal trenches but appear to be absent from the deepest parts of the oceans, >9000 m deep. There have been six global oceanic anoxic events (OAE) since the origin of the major fish taxa in the Devonian c. 400 million years ago (mya). Colonization of the deep sea has taken place largely since the most recent OAE in the Cretaceous 94 mya when the Atlantic Ocean opened up. Patterns of global oceanic circulation oxygenating the deep ocean basins became established coinciding with a period of teleost diversification and appearance of the Acanthopterygii. Within the Actinopterygii, there is a trend for greater invasion of the deep sea by the lower taxa in accordance with the Andriashev paradigm. Here, 31 deep-sea families of Actinopterygii were identified with mean maximum depth >1000 m and with >10 species. Those with most of their constituent species living shallower than 1000 m are proposed as invasive, with extinctions in the deep being continuously balanced by export of species from shallow seas. Specialized families with most species deeper than 1000 m are termed deep-sea endemics in this study; these appear to persist in the deep by virtue of global distribution enabling recovery from regional extinctions. Deep-sea invasive families such as Ophidiidae and Liparidae make the greatest contribution to fish fauna at depths >6000 m.

Pepemkay maya, gen. et sp. nov., is described based on a single complete specimen collected in El Chango Quarry, a marine Cenomanian limestone outcrop of the Sierra Madre Formation, near Tuxtla Gutierrez, Chiapas State, southern Mexico. This species is identified as a new member of the Lissoberycinae and differs from other genera of this subfamily because it has an unornamented skull; bones of opercular series with non-spiny posterior borders; dorsal fin with five spines and eight soft rays; pelvic fin including a spine plus three branched soft rays; predorsal formula 0+0/0/1+1/; cycloid scales in the caudal peduncle and anterior half of the body, crenate scales between these body regions; and at least one scale on the opercle and other over the quadrate. Pepemkay maya is the first Trachichthyidae and Lissoberycinae fish found in marine Cretaceous deposits of America; its discovery complements our comprehension on the taxonomical diversity of fossil Trachichthyidae and supports the efforts direct...

A redescription and diagnosis of Trimma tevegae , based on 50 additional specimens from the type locality at Rabaul, New Britain is provided, and contrasted with the redescription and diagnosis of T. caudomaculatum , based on the type material and an additional 22 specimens from various western Pacific localities. Trimma tevegae may most easily be recognized by the lack of a blue stripe (dark in preservative) in the dorsal midline of the snout, and a short second spine in the first dorsal fin, reaching posteriorly to the origin or first few ray bases of the second dorsal fin. Trimma caudomaculatum can be identified by the blue stripe from the snout along the dorsal midline, the blue spots and stripes in front of the eye, on the opercle and beneath the eye (dark in preserved material), and the very elongate second dorsal spine, usually extending to beyond the end of the second dorsal fin. Three similar-looking new species are described. Trimma burridgeae and T. hollemani are morphologically very close to each other, differing mainly in the length of the second dorsal spine (to the posterior base of the second dorsal fin or beyond in T. burridgeae ; to the anterior base of that fin in T. hollemani ). These two species differ by over 9% of the bases of the COI gene. Trimma corerefum is the most distinctive of the species, differing in lacking a blue stripe on the dorsal surface of the snout, in the pigment pattern around the eye, in having fewer cephalic sensory papillae (free neuromasts) in rows d ʹ, ea , ep , f, r and ot , and in a shorter fifth pelvic fin ray (34–45% length of fourth pelvic ray). The morphological differences between the species are reinforced by the results of a barcode analysis of the COI gene, based on 105 specimens.

Dear Sir, Chromatophores are large, stellate and spectacular pigment bearing cells, typically located in the skin, that generate body colouration. In many animals, melanocytes ⁄melanophores, the melanin containing chromatophores, are also present in various tissues inside the body, for instance in the ear, brain, abdominal cavity, around internal organs and skeleton. The presence of such internal pigmentation in puzzling as it is hidden from sight. While there is an enormous amount of studies and data on skin chromatophores, from the fine details of the motile machinery to animal behaviour (Aspengren et al., 2009), internal melanocytes have historically been largely ignored, until recently (Aoki et al., 2009; Brito and Kos, 2008; Randhawa et al., 2009; Yajima and Larue, 2008). Remarkably little is still known about their possible functions, and this uncertainty is problematic for the more general question of the role(s) of melanin in itself (Aspengren et al., 2009; Boissy and Hornyak, 2006; Braasch et al., 2009; Hill, 2000; Ito, 2009). While internal melanocytes are prevalent, internal erythrophores and xanthophores appear more uncommon. In fish, however, such cells can be found interspersed with melanocytes and reflective chromatophores in the highly pigmented peritoneum (the endothelium that covers the abdominal cavity) (Nilsson Skold et al., 2008). In juveniles, as well as in adults of species with relatively transparent bodies, internal chromatophores may actually contribute to the overall body colouration, as shown in two-spotted goby females, where abdominal trunk biopsies were analysed (Nilsson Skold et al., 2008). In fishes, skin patterns can be rapidly modified by aggregation or dispersion of the pigment-containing organelles inside the chromatophores present in the skin (i.e. physiological colour change) for background adaptation or signalling displays (Aspengren et al., 2009; Fujii and Oshima, 1994). In comparison, colour change in internal chromatophores has been largely ignored as it has been generally considered that they are not responsive (Boissy and Hornyak, 2006). However, melanocytes in the peritoneum and around the skeleton of the ice goby, Leucopsarion petersii, do indeed adapt to the background by pigment translocations in vivo and in biopsies, thus providing the first evidence for internal colour change (Goda and Fujii, 1996). Recent work on biopsies from the two-spotted goby showed that also internal erythrophores and xanthophores can be responsive (Nilsson Skold et al., 2008). As these examples come from relatively transparent species, it is possible that this phenomenon is more common than earlier believed, especially in species with some degree of body transparency. In order to test if a capacity for internal colour change was related to the degree of body transparency, and to reveal a possible function of these cells, we analysed the regulatory capability of peritoneal melanocytes in eight different teleost species, representing five different orders within the large super order Acanthopterygii and in one member of the super order Clupeomorpha, all with different degrees of body transparency. We used epinephrine and melatonin as potential pigment aggregating agents (see Appendix S1 for methodology). A positive relationship between body transparency and rate of internal colour change would suggest a special adaptive role for internal melanocytes in transparent fish species, and thus constitute a novel function for internal pigments. Our results showed that peritoneal melanocytes were present in all investigated fish species. Especially high densities were found in the gobies and in pipefish, plaice and herring (Figure 1A, B). Internal erythrophores and xanthophores were also observed in the gobies, pipefish and in plaice, but not in the other species. A capacity to regulate peritoneal melanocytes by melatonin and epinephrine was detected in six out of the eight species (Figure 1A, B and Table S1). In all species tested, peritoneal melanocytes had dispersed pigment from the start of the experiment. The epidermal melanocytes of sand goby, black goby and wrasse responded within 30 min, whereas plaice and pipefish only responded appreciably after 2 h. In herring, both controls and treated peritoneum biopsies showed a response after 30 min with an only moderate further

The gilthead seabream and the soles, Senegalese sole and common sole, are important species in Mediterranean aquaculture. In this chapter, a review of the current genomic resources available for these species is carried out. First, transcriptome information, their main characteristics, and the high-throughput gene expression tools developed in these three species are described. Second, the current genetic maps and their applications for the identification of QTLs for traits of interest in aquaculture are also reported. Moreover, the main features of Senegalese sole genome draft are analyzed and its structure is compared with other Acanthopterygii confirming a high degree of synteny that allows for comparative genomic studies. To show the relevance of these genomic resources to enhance the aquaculture procedures, the SoleaDB database that hosts the genomic information for soles is described. Moreover, main results obtained using transcriptomic tools to decipher the regulatory pathways that control larval development, nutrition and metabolism, as well as the health and welfare status are reviewed. Future directions of genomic research and the impact of novel species-specific applications and resources are highlighted.

Basic and neutral neurohypophyseal (NH) nonapeptides have evolved from vasotocin (VT) by a gene duplication at the base of the gnathostome lineage. In teleosts, VT and IT are the basic and neutral peptides, respectively. In the present study, VT and IT precursor genes of Heteropneustes fossilis and Clarias batrachus (Siluriformes, Ostariophysi) were cloned and sequenced. The channel catfish Icatalurus punctatus NH precursor sequences were obtained from EST database. The catfish NH sequences were used along with the available Acanthopterygii and other vertebrate NH precursor sequences to draw phylogenetic inference on the evolutionary history of the teleost NH peptides. Synteny analysis of the NH gene loci in various teleost species was done to complement the phylogenetic analysis. In H. fossilis, the NH transcripts were also sequenced from the ovary. The cloned genes and the deduced precursor proteins showed conserved characteristics of the NH nonapeptide precursors. The genes are expressed in brain and ovary (follicular envelope) of H. fossilis with higher transcript abundance in the brain. The addition of the catfish sequences in the phylogenetic analysis revealed that the VT and IT precursors of the species-rich superorders of teleosts have a distinct phylogenetic history with the Acanthopterygii VT and IT precursors sharing a less evolutionary distance and the Ostariophysi VT and IT having a greater evolutionary distance. The genomic location of VT and IT precursors, and synteny analysis of the NH loci lend support to the phylogenetic inference and suggest a footprint of fish- specific whole genome duplication (3R) and subsequent diploidization in the NH loci. The VT and IT precursor genes are most likely lineage-specific paralogs resulting from differential losses of the 3R NH paralogs in the two superorders. The independent yet consistent retention of VT and IT in the two superorders might be directed by a stringent ligand-receptor selectivity.

Pituitaries of various teleosts belonging to 25 orders were immunostained with antisera raised against synthetic fragment peptides corresponding to conservative regions of gonadotropinβ subunits (mummichog FSHβ 50-60 and mummichog LHβ 91-106). Both immunoreactive FSH cells and immunoreactive LH cells were successfully identified in the fishes of almost every order of the superorder Acanthopterygii and several species of the superorders Paracanthopterygii and Polymixiomorpha, such as mullet, alfonsino, flyingfish, mackerel, flounder, cod, beardfish, etc. These antisera are therefore considered as universal antisera for immunocytochemical application to acanthopterygian fishes. Extensive diversity in the abundance of the FSH cells and the LH cells among species was noted even in fishes with similar gonadal stages, indicating the possibility that the respective roles of FSH and LH may vary considerably among species in advanced teleosts. Evident but generally weak immunoreactivities to anti-mummichog LHβ 91-106 were observed in the fishes of the superorder Cyclosquamata; and slight or weak immunoreactivities to the antiserum were observed in the fishes of several more primitive taxa (superorder Stenopterygii, Protacanthopterygii, Ostariophysi, subdivision Clupeomorpha, and subdivision Elopomorpha). No immunoreactivity to anti-mummichog FSHβ 50-60 was observed in these fishes. These results are consistent with the phylogenetic status of the fishes and the degree of conservativeness in the amino acid sequences of the antigen regions.

Recent studies with cyprinid and characin (superorder Ostariophysi) fishes suggest that purine-N-oxides function as chemical alarm cues (alarm pheromones) and that the nitrogen oxide functional group acts as the chief molecular trigger. To further test the hypothesis that the nitrogen-oxide functional group is evolutionarily conserved as an active component of the Ostariophysan alarm pheromone system, we exposed juvenile channel catfish (Ictalurus punctatus, Siluriformes) to conspecific skin extract, hypoxanthine-3-N-oxide (the putative alarm pheromone) and a suite of structurally and functionally similar compounds. Conspecific skin extract and hypoxanthine-3-N-oxide elicited significant increases in species typical antipredator behaviors. A structurally dissimilar compound possessing a nitrogen oxide functional group (pyridine-N-oxide) elicited a significant, but less intense alarm response. Compounds lacking a nitrogen oxide functional group were not significantly different from control stimuli. In addition, two non-Ostariophysan species known to possess chemical alarm cues (convict cichlids, Acrchocentrus nigrofasciatus, Cichlidae, Acanthopterygii and rainbow trout, Oncorhynchus mykiss, Salmonidae, Protacanthopterygii) did not show any increase in antipredator behavior in response to hypoxanthine-3-N-oxide. These data demonstrate the conservation of chemical alarm cues within at least three orders of the superorder Ostariophysi.

The taxon Beloniformes represents a heterogeneous group of teleost fishes that show an extraordinary diversity of jaw morphology. I present new anatomical descriptions of the jaw musculature in six selected beloniforms and four closely related species. A reduction of the external jaw adductor (A1) and a changed morphology of the intramandibular musculature were found in many Beloniformes. This might be correlated with the progressively reduced mobility of the upper and lower jaw bones. The needlefishes and sauries, which are characterised by extremely elongated and stiffened jaws, show several derived characters, which in combination enable the capture of fish at high velocity. The ricefishes are characterised by several derived and many plesiomorphic characters that make broad scale comparisons difficult. Soft tissue characters are highly diverse among hemiramphids and flying fishes reflecting the uncertainty about their phylogenetic position and interrelationship. The morphological findings presented herein may help to interpret future phylogenetic analyses using cranial musculature in Beloniformes.

Myersina is redefined, based on the presence of an elongate first dorsal fin in at least the adult males, two preopercular pores, gill membranes fused in the ventral midline and either fused to the isthmus or forming a free fold over it, cycloid scales only on the body, and midline of predorsal region scaleless. It now includes four species traditionally assigned to Cryptocentrus but here placed in Myersina ("C". crocatus, "C". filifer, "C". pretoriusi, and "C". yangii). This concept of Myersina still retains the species originally assigned to it (M. macrostoma, M. lachneri, and M. nigrivirgata). The recently described M. larsonae belongs in Stonogobiops. These two genera almost definitely form a monophyletic group. However, it is possible that the species of Stonogobiops (the monophyly of which is well supported) could be more closely related to one or more species of Myersina than either is to other Myersina species, because the monophyly of the latter genus remains uncertain.

We record the presence of 35 cardinalfish species from the marine waters of Singapore based on a review of existing literature and examination of museum specimens. Another 13 species previously recorded as occurring in Singapore are considered doubtful records. Five of the 35 species reported here (Apogon crassiceps, Apogonichthyoides timorensis, Jaydia lineata, Nectamia similis, and Siphamia tubifer) are new records for Singapore, while another four species have not been encountered in more than a century.

This work was funded by the Marine Alliance for Science and Technology for Scotland pooling initiative and Scottish Funding Council grant number HR09011. Teleost fish underwent whole-genome duplication around 450 Ma followed by diploidization and loss of 80-85% of the duplicated genes. To identify a deep signature of this teleost-specific whole-genome duplication (TSGD), we searched for duplicated genes that were systematically and uniquely retained in one or other of the superorders Ostariophysi and Acanthopterygii. TSGD paralogs comprised 17-21% of total gene content. Some 2.6% (510) of TSGD paralogs were present as pairs in the Ostariophysi genomes of Danio rerio (Cypriniformes) and Astyanax mexicanus (Characiformes) but not in species from four orders of Acanthopterygii (Gasterosteiformes, Gasterosteus aculeatus; Tetraodontiformes, Tetraodon nigroviridis; Perciformes, Oreochromis niloticus; and Beloniformes, Oryzias latipes) where a single copy was identified. Similarly, 1.3% (418) of total gene number represented cases where TSGD paralogs pairs were systematically retained in the Acanthopterygian but conserved as a single copy in Ostariophysi genomes. We confirmed the generality of these results by phylogenetic and synteny analysis of 40 randomly selected linage-specific paralogs (LSPs) from each superorder and completed with the transcriptomes of three additional Ostariophysi species (Ictalurus punctatus [Siluriformes], Sinocyclocheilus species [Cypriniformes], and Piaractus mesopotamicus [Characiformes]). No chromosome bias was detected in TSGD paralog retention. Gene ontology (GO) analysis revealed significant enrichment of GO terms relative to the human GO SLIM database for "growth," "Cell differentiation," and "Embryo development" in Ostariophysi and for "Transport," "Signal Transduction," and "Vesicle mediated transport" in Acanthopterygii. The observed patterns of paralog retention are consistent with different diploidization outcomes having contributed to the evolution/diversification of each superorder. Publisher PDF

Swordtail fishes and platies in the genus Xiphophorus (order Cyprinodontiformes, Teleostei) encompass 22 closely related species which are the products of a recent adaptive radiation in the streams of Central America. To investigate the evolution of the major histocompatibility complex (Mhc) genes in the period immediately following speciation, the class I genes from 20 of the 22 species were cloned and characterized by sequencing. The analysis revealed the existence of multiple loci (at least seven in some individuals) whose numbers vary among the different species and probably also among individuals of the same species. The variation does not seem to bear any relationship to the taxonomy of the genus. Genes at the different loci are distinguished by their intron sequences and by the presence of characteristic motifs in exons 2 and 3. The variation in copy number of loci may have been effected in part by unequal crossing over occurring between introns of misaligned closely related genes. The sequences of the genes fall into two groups, A and B, which represent ancient lineages. The groups define two families of loci, which diverged from each other an estimated 85 million years ago, before the separation of the Acanthopterygii from the Paracanthopterygii of the advanced bony fishes. Evolution of the genes within each family can be explained by the birth-and-death process driven by gene duplications and mutational differentiation.

We cloned and sequenced the complete mitochondrial genome of Japanese flounder (Paralichthys olivaceus). A circular 17,090 bp mitochondrial genome from the flounder contains 37 structural genes as in other vertebrates so far reported. This is the first report of the complete mitochondrial sequence from a higher teleostean fish (Acanthopterygii). The organization including gene order is quite similar to that of other teleostean fishes as well as placental mammals. The putative control region of the Japanese flounder mitochondrial genome contains a length variable region of about a 74 bp tandem repeat cluster. As a preliminary study we adopted the maximum likelihood and neighbor-joining inference methods to examine phylogenetic relationships among teleostean and related fishes. Comparisons of amino acid sequences of protein-coding genes and nucleotide sequences of tRNA genes resolved some middle to deep branches among some teleostean fishes. The flounder mitochondrial genome does not show an indication of evolutionary rate difference among teleosts leading to difficulty in phylogenetic analyses, and our data is useful for future evolutionary studies dealing with higher teleostean fishes.

We have characterized the sperm nuclear basic proteins (SNBPs) of the sticklebacks in the suborder Gasterosteoidei. The complete amino acid sequence of the protamines from Aulorhynchus flavidus, Pungitius pungitius, Gasterosteus aculeatus, (anadromous) and G. wheatlandi, as well as the sequences of the protamines of several species pairs of freshwater G. aculeatus, have been determined. Analysis of the primary structure of these proteins has shown that: a) despite the relatively low amino acid complexity and small molecular mass of these basic proteins, they are very good molecular markers at the generic level. The bootstrap parsimony analysis using their sequences provides a phylogenetic relationship for the old anadromous species of Gasterosteoidei which is identical to that obtained from morphological and behavioral analysis; b) the comparison of the sequences also suggests that protamines from the suborder Gasterosteoidei have most likely evolved from a common gene in the early Acanthopterygii by an extension of the carboxy terminal portion of the molecule; c) protamines are not good markers for recent postglacial freshwater isolates of G. aculeatus. However, in the unique case of Enos Lake (British Columbia), we have been able to detect an additional minor protamine component in the benthic forms of G. aculeatus that is not present in the limnetic forms. Thus, this new protamine must have appeared during the past 12,000 years concomitantly with the speciation of benthics and limnetics in this lake.

To date, growth hormone (GH) is known to contribute to seawater adaptation only in salmonid fishes (primitive Euteleostei). Accordingly, the effects of homologous GH and two forms of homologous prolactin (PRL177 and PRL188) on hypoosmoregulatory ability and gill Na+,K(+)-ATPase activity in a more advanced euryhaline cichlid fish, the tilapia (Oreochromis mossambicus), were examined. Following adaptation of hypophysectomized fish to 25% seawater for 3 weeks, fish were given four injections of hormone or vehicle. They were then exposed to 100% seawater for 12 hr and examined for changes in plasma osmolality. Tilapia GH (0.02 and 0.2 microgram/g) significantly improved the ability of tilapia to decrease plasma osmolality following transfer to full-strength seawater, in a dose-related manner. Growth hormone treatment also significantly stimulated gill Na+,K(+)-ATPase activity (0.5 microgram/g). Both tilapia PRLs (PRL177 and PRL188) increased plasma osmolality in 100% seawater and reduced gill Na+,K(+)-ATPase activity, the effects induced by PRL188 being more significant than those by PRL177. Thus, GH may be involved in seawater adaptation of tilapia, a species belonging to the most advanced teleost super-order (Acanthopterygii), whereas both PRLs in tilapia are not involved in seawater adaptation.

The objective of the present study was to investigate the feeding habits allowing the occurrence of the congeneric species Stellifer rastrifer and Stellifer brasiensis, collected on a seasonal basis, in the operating area of the artisanal seabob-shrimp trawl fishery in Porto Belo, an important fishing area on the southern Brazilian coast. Fish were collected seasonally from November 2009 to August 2010, in isobaths of 10, 20 and 30m. Of the 450 stomachs analyzed, 194 belongd to Stellifer rastrifer and 242 to Stellifer brasiliensis. From the totality of analyzed stomachs 33.49% were empty and 66.52% had some content. Crustacea were the predominant food category in the diet of S. rastrifer and S. brasiliensis, and the shrimp Acetes americanus was the most frequent crustacean in stomachs of both studied species. The overlapping in the diet of the species was high, however when analyzing the overlap in each season it was found that it occurred only during spring and winter. Although the most important items in the diet of these species are the same, the intake of each alternates in time, suggesting a difference in predation pressure, which leads to less direct competition in a given time.

Records of the anthiine fish genus Meganthias are rare and most species are only known from few specimens. On 17 February 2012 a specimen of Meganthias natalensis, ~400 mm standard length was caught in 150 m depth about 10 nautical miles off Watamu, Kenya. This is the first record of the species from Kenyan waters.

Multiple forms of gonadotropin releasing hormone (GnRH) are found within several species of teleost fishes. Within the infradivision Euteleostei, the superorder Paracanthopterygii represents one of the last major groups to be examined with respect to the GnRH mRNA sequence. The plainfin midshipman, Porichthys notatus, is a common member of this superorder which is intermediate between the ancestral euteleost taxa and the more derived Acanthopterygians (percomorphs). The goals of this study were to: (1) determine the cDNA sequence of prepro-GnRH in the plainfin midshipman, (2) address the anatomical localization of midshipman prepro-GnRH gene expression, and (3) perform a cladistic analysis using all currently known cDNA sequences of prepro-GnRH. We report 460 base pair of cDNA sequence containing the entire protein coding region, and 5'- and 3'-untranslated regions. The deduced amino acid sequence indicates that this cDNA encodes a GnRH decapeptide identical in sequence to that originally isolated in salmon (Trp7, leu8 - GnRH). Northern analysis demonstrated transcripts in brain, ovary, and testis (600-700 nucleotides). PCR showed that the ovarian prepro-GnRH was identical to that found in brain. In situ hybridization labeled neurons in the ganglion of the terminal nerve and the preoptic area, forebrain areas previously observed to contain GnRH-like immunoreactivity. Last, a phylogenetic analysis of 18 prepro-GnRH sequences grouped the Paracanthopterygii with the Acanthopterygii. However, this recent clade was distinct from two separate and more ancestral lineages, the Paracanthopterygii (salmonids) and Ostariophysi (represented by catfish).

Sovint, la sistemàtica, basada principalment en caràcters morfològics, no es correspon amb els processos evolutius relacionats amb l'aparició dels grups d'organismes. En l'actualitat, la utilització de les dades moleculars es fa indispensable per a una revisió i millora de la classificació biològica de diversos organismes, com els peixos Acanthopterygii. A la sèrie Mugilomorpha la incongruència entre la taxonomia i la filogènia sorgeix de l'elevada semblança morfològica trobada per part dels seus membres. Pel que fa referència a la sèrie Atherinomorpha, la problemàtica principal resideix en determinar la seva proximitat evolutiva respecte a la sèrie anterior i en establir les relacions filogenètiques dins de la mateixa. Per tant, s'hi ha volgut estimar tant la divergència genètica dins de cada sèrie com inferir les relacions filogenètiques entre ambdues mitjançant la seqüenciació directa del DNA de les regions mitocondrials corresponents al tRNA-Phe, 12S rRNA, COI, cytb, tRNA-Thr, tRNA-Pro i regió control., Often, systematics, based mainly on morphologic characters, does not correspond with the evolutionary processes related to the emergence of the groups of organisms. Nowadays, the utilization of molecular data turns indispensable to a revise and improve the biological classification of several organisms, such as Acanthopterygii fishes. In series Mugilomorpha, the incongruence between taxonomy and phylogeny arises from the high morphological similarity found between its members. Concerning series Atherinomorpha, the main problem lies in determining its evolutionary proximity in relation to series Mugilimorpha and in establishing the phylogenetical relationships inside itself. Therefore, both genetic divergence within each series and phylogenetical relationships between them have been wanted to estimate. For this reason, the direct sequencing of the mitochondrial regions corresponding to tRNA-Phe, 12S rRNA, COI, cytb, tRNA-Thr, tRNA-Pro and control region was achieved.

Brain acetylcholinesterase (AChE) of some fishes from the coast of Rio de Janeiro State was studied as a possible pesticide biomarker in marine environmental monitoring. AChE specific activity in brain varied from 145 to 530 U/g of proteins and the Michaelis–Menten constant (KM) for acetylthiocholine varied from 104 to 291 μM among the 20 species studied. The enzyme sensitivity to methyl paraoxon, evaluated by the inhibition kinetic constants, shows that some species (Paralonchurus brasiliensis and Genidens genidens) are more sensitive (IC50-30 min = 455 and 468 nM, respectively). The less sensitive Merluccius hubbsi and Percophis brasiliensis (IC50-30 min = 3339 and 3259 nM, respectively) belong to the super-order Paracanthopterygii, which includes the more ancient species. On the other hand, more susceptible species belong to the super-order Acanthopterygii, which includes more recent species. These results suggest a possible evolutionary linkage for AChE sensitivity to methyl paraoxon. The application of inhibition kinetic constants for fish brain AChE in phylogenetic studies is still being investigated. The results have shown that a fish sentinel species should have the highest brain AChE level among the more sensitive ones.

Using gene cloning and in silico cloning, we analyzed the structures of hatching enzyme gene orthologs of vertebrates. Comparison led to a hypothesis that hatching enzyme genes of Japanese eel conserve an ancestral structure of the genes of fishes, amphibians, birds and mammals. However, the exon-intron structure of the genes was different from species to species in Teleostei: Japanese eel hatching enzyme genes were 9-exon-8-intron genes, and zebrafish genes were 5-exon-4-intron genes. In the present study, we further analyzed the gene structures of fishes belonging to Acanthopterygii. In the species of Teleostei we examined, diversification of hatching enzyme gene into two paralogous genes for HCE (high choriolytic enzyme) and LCE (low choriolytic enzyme) was found only in the acanthopterygian fishes such as medaka Oryzias latipes, Fundulus heteroclitus, Takifugu rubripes and Tetraodon nigroviridis. In addition, the HCE gene had no intron, while the LCE gene consisted of 8 exons and 7 introns. Phylogenetic analysis revealed that HCE and LCE genes were paralogous to each other, and diverged during the evolutionary lineage to Acanthopterygii. Analysis of gene synteny and cluster structure showed that the syntenic genes around the HCE and LCE genes were highly conserved between medaka and Teraodon, but such synteny was not found around the zebrafish hatching enzyme genes. We hypothesize that the zebrafish hatching enzyme genes were translocated from chromosome to chromosome, and lost some of their introns during evolution.

In this study we use a taxon-based approach to examine previous, as well as new findings on several topics pertaining to the peripheral olfactory components in teleost fishes. These topics comprise (1) the gross anatomy of the peripheral olfactory organ, including olfactory sensory neuron subtypes and their functional parameters, (2) the ultrastructure of the olfactory epithelium, and (3) recent findings regarding the development of the nasal cavity and the olfactory epithelium. The teleosts are living ray-finned fish, and include descendants of early-diverging orders (e.g., salmon), specialized descendants (e.g., goldfish and zebrafish), as well as the Acanthopterygii, numerous species with sharp bony rays, including perch, stickleback, bass and tuna. Our survey reveals that the olfactory epithelium lines a multi-lamellar olfactory rosette in many teleosts. In Acanthopterygii, there are also examples of flat, single, double or triple folded olfactory epithelia. Diverse species ventilate the olfactory chamber with a single accessory nasal sac, whereas the presence of two sacs is confined to species within the Acanthopterygii. Recent studies in salmonids and cyprinids have shown that both ciliated olfactory sensory neurons (OSNs) and microvillous OSNs respond to amino acid odorants. Bile acids stimulate ciliated OSNs, and nucleotides activate microvillous OSNs. G-protein coupled odorant receptor molecules (OR-, V1R-, and V2R-types) have been identified in several teleost species. Ciliated OSNs express the G-protein subunit G(alphaolf/s), which activates cyclic AMP during transduction. Localization of G protein subunits G(alpha0) and G(alphaq/11) to microvillous or crypt OSNs, varies among different species. All teleost species appear to have microvillous and ciliated OSNs. The recently discovered crypt OSN is likewise found broadly. There is surprising diversity during ontogeny. In some species, OSNs and supporting cells derive from placodal cells; in others, supporting cells develop from epithelial (skin) cells. In some, epithelial cells covering the developing olfactory epithelium degenerate, in others, these retract. Likewise, there are different mechanisms for nostril formation. We conclude that there is considerable diversity in gross anatomy and development of the peripheral olfactory organ in teleosts, yet conservation of olfactory sensory neuron morphology. There is not sufficient information to draw conclusions regarding the diversity of teleost olfactory receptors or transduction cascades.

DNA sequence and morphological data were analyzed for specimens of twenty-five species of acanthomorph fishes and two specimens representing the outgroups Aulopiformes and Myctophiformes. A 572 base-pair (bp) segment of the 12S ribosomal mitochondrial gene, 1112 bp from three regions of the 28S ribosomal nuclear gene, and 38 morphological transformation series were analyzed under the criterion of maximum parsimony. The total evidence analysis resulted in a set of four most parsimonious trees. Relationships common to all trees are largely congruent with the hypothesis articulated by Johnson and Patterson (1993. Bull. Mar. Sci. 52, 554–626).

The adductor mandibulae complex has been a subject of discussion and uncertainties due to a wide range of differentiations and fusions that have occurred during teleost evolution. The adductor mandibulae of numerous catfishes was studied in detail and compared with that of several other teleosts described in the literature. Our observations and comparisons demonstrate that: 1) the adductors mandibulae Aomega, A2, and A3 of acanthopterygians correspond, respectively, to the Aomega, A2, and A3 of ostariophysines; 2) the antero-dorso-lateral (A1) and the antero-ventro-lateral (A1-OST) sections of the adductor mandibulae present, respectively, in acanthopterygians and in basal ostariophysines are the result of two different patterns of differentiation of this muscle; 3) some derived ostariophysines present a lateral section of the adductor mandibulae attached to the upper jaw (A0) that is not homologous with any other section of this muscle present in any other ostariophysine or acanthopterygian fish; 4) the configuration of the adductor mandibulae present in Diplomystes seems to be the plesiomorphic condition for catfishes; and 5) the muscle retractor tentaculi, present in a large number of catfishes, is derived from the inner section of the adductor mandibulae (A3) and, thus, is not homologous with the lateral bundle of this muscle (A0) that inserts on the upper jaw in some derived ostariophysine fishes.

Hyphessobrycon simulans has a Weberian apparatus for transmission of sound energy to the auditory organ, whereas Poecilia reticulata does not. The fine structure of the auditory organs is identical in the two species. The better hearing - expressed by large bandwidth and high sensitivity - typical of the Ostariophysi - seems to be based exclusively on the presence of the Weberian apparatus. The sensory epithelium of the saccule and the lagena is made up of hair (sensory) cells and supporting cells. The vertically orientated macula sacculi is divided into a dorsal and a ventral cell area with oppositely arranged hair-cell kinocilia. The sagitta takes up the center of the saccule and shows only three small sites with connections to the otolithic membrane. Remarkably, the dorsal sensory cells are connected to the ventral part of the otolith, but the ventral cells are connected to the dorsal part. The macula of the lagena also comprises a dorsal and a ventral cell area with oppositely arranged hair cells. The sensory cells in all maculae are of type II. They exhibit a striking apical cell protrusion, the cuticular villus. It is partially fused with the kinocilium in the contact zones and joined to the otolithic membrane. The cuticular villus probably stabilizes the long kinocilia.

The chapter focuses on the classification of intertidal fishes. Modern classifications of fishes are based on principles of phylogenetic systematics, which is strictly genealogical, and phylogenetic classifications communicate evolutionary history. The chapter also provides a descriptive paragraph for each family of fishes represented in the intertidal ichthyofaunal assemblage along with a summary of the taxonomic distribution of rocky intertidal fishes at the levels of class and order. It was observed that with a single elasmobranch exception, the classes Myxini, Cephalaspidomorphi, Chondrichthyes, and Sarcopterygii do not presently contribute to the rocky intertidal ichthyofauna. Within the Class Acrinopterygii, strictly freshwater species are (obviously) not reported from the intertidal zone, even as strays; diadromous species are negligible components of the intertidal ichthyafauna. Intertidal fish species are concentrated within the two most derived superorders of the Euteleostei, the Paracanthopterygii, and the Acanthopterygii. Within the latter group, the percomorph orders Scorpaeniformes and Perciformes contain the most intertidal species.

We present morphological, immunocytochemical and developmental studies on the macroglia of species of two groups of teleosts carried out in our laboratories. One of these species, the grey mullet (Chelon labrosus; Acanthopterygii), is an advanced euteleost. The other species are trouts (Salmo trutta fario, Oncorhynchus mykiss; Protacanthopterygii) which belong to the basal stock of euteleosts. We present our results on a specialized astroglial structure of the medulla oblongata of the adult grey mullet, the distribution of astroglial markers (vimentin, GFAP and S-100) in the brain of the adult mullet and their pattern of expression in juveniles of 5 to 70 mm in length, as well as results obtained with S-100 and GFAP immunocytochemistry in trout. In old adult mullet (circa 50 cm in length), we have studied with light and electron microscopy the diversity of oligodendrocytes of the lateral line area of the medulla oblongata. In the brain of old adult trout (circa of 36 cm in length), the NADPHd histochemical reaction was used to study the large population of oligodendrocytes. Finally, we studied the development of the oligodendrocytes in trout using an antibody to the 36K myelin protein. Our results in old adults of two species pertaining to different lines within teleosts showed that diversity of oligodendrocyte sizes in different regions of the brain is a shared characteristic of teleosts and mammals.

A new stichaeid fish, Ernogrammus zhirmunskii is described on the basis of the specimens collected in Peter the Great Bay, the Sea of Japan. This new species differs from its congeners E. hexagrammus and E. walkeri in having seven body sensory canals in total number including one short canal in the middle of belly and unique combination in number of the anal fin rays with one short rigid spine posteriormost (I 28-30 I). In coloration the fish has one narrow white stripe between two wide black ones on the base of pelvic fin, and one dark blotch on the dorsal fin anteriorly.

Background The order Tetraodontiformes consists of approximately 429 species of fishes in nine families. Members of the order exhibit striking morphological diversity and radiated into various habitats such as freshwater, brackish and coastal waters, open seas, and deep waters along continental shelves and slopes. Despite extensive studies based on both morphology and molecules, there has been no clear resolution except for monophyly of each family and sister-group relationships of Diodontidae + Tetraodontidae and Balistidae + Monacanthidae. To address phylogenetic questions of tetraodontiform fishes, we used whole mitochondrial genome (mitogenome) sequences from 27 selected species (data for 11 species were newly determined during this study) that fully represent all families and subfamilies of Tetraodontiformes (except for Hollardinae of the Triacanthodidae). Partitioned maximum likelihood (ML) and Bayesian analyses were performed on two data sets comprising concatenated nucleotide sequences from 13 protein-coding genes (all positions included; third codon positions converted into purine [R] and pyrimidine [Y]), 22 transfer RNA and two ribosomal RNA genes (total positions = 15,084). Results The resultant tree topologies from the two data sets were congruent, with many internal branches showing high support values. The mitogenomic data strongly supported monophyly of all families and subfamilies (except the Tetraodontinae) and sister-group relationships of Balistidae + Monacanthidae and Tetraodontidae + Diodontidae, confirming the results of previous studies. However, we also found two unexpected basal splits into Tetraodontoidei (Triacanthidae + Balistidae + Monacanthidae + Tetraodontidae + Diodontidae + Molidae) and Triacanthodoidei (Ostraciidae + Triodontidae + Triacanthodidae). Conclusion This basal split into the two clades has never been reported and challenges previously proposed hypotheses based on both morphology and nuclear gene sequences. It is likely that the basal split had involved ecological diversification, because most members of Tetraodontoidei exclusively occur in shallow waters (freshwater, brackish and coastal waters, and open seas), while those of Triacanthodoidei occur mainly in relatively deep waters along continental shelves and slopes except for more derived ostraciids. This suggests that the basal split between the two clades led to subsequent radiation into the two different habitats.

The choroid rete mirabile is a vascular counter-current organ located behind the retina of the eye and responsible in part for the maintenance of a high partial pressure of oxygen there. It is absent in cyclostomes, elasmobranchs, and all living non-teleost bony fishes with the exception of the holostean, Amia calva. The choroid rete is found widely distributed among teleosts and is nearly always present in the Acanthopterygii, which comprise the great majority of living forms. The ability to do without a choroid rete typifies families or orders, but is a character of limited phyletic usefulness. There seems little correlation between habitat and presence or absence of the choroid rete. The choroid rete and the rete mirabile of the swimbladder occur independently. This does not seem to be true for the choroid rete and the pseudobranch, Since almost all fishes which have a choroid rete also have a pseudobranch. Arterial blood comes to the choroid rete mirabile by way of the pseudobranch, and those instance...

The pelvic spine articulation in 88 non-squamipinne acanthopterygian species belonging to 59 families and 8 orders was examined. For most acanthopterygians, the pelvic bone lacks a foramen for the attachment of the pelvic spine flanges and this structural condition is considered a primitive acanthopterygian state. Only in Caproidae, Leiognathidae, and Polynemidae among the examined species do the pelvic spine flanges fuse through a foramen in the pelvic bone and this articulation is considered most derived. In the remaining acanthopterygians examined, the pelvic spine flanges butt against each other through the pelvic foramen. However, these flanges do not fuse. This structure is considered an intermediate state. The possible phylogenetic implication of these articulating states regarding acanthopterygian phylogeny is discussed.