Search

Over a century after the first description of a polymorphism controlled by a supergene, these genetic architectures still puzzle biologists. Supergenes are groups of tightly linked loci facilitating the co-segregation of combinations of alleles underlying alternative, complex adaptive strategies. The suppression of recombination at supergenes is generally caused by polymorphic chromosomal rearrangements, such as inversions. The existence of inversion polymorphisms and supergene raises theoretical and empirical questions. Why do these architectures evolve? How can alternative combinations of alleles be formed? How and why is polymorphism maintained? The purpose of this paper is to provide answers to these questions by reviewing recent advances in the study of Heliconius numata, an Amazonian butterfly displaying a striking diversity of wing color patterns. In a broad context, this review highlightsmechanisms that play an important role in the evolution of new genomic architecture and in the adaptation of species. [ABSTRACT FROM AUTHOR]

Most bacterial ribonucleases (RNases) known to date have been identified in either Escherichia coli or Bacillus subtilis. These two organisms lie on opposite poles of the phylogenetic spectrum, separated by 1-3 billion years of evolution. As a result, the RNA maturation and degradation machineries of these two organisms have little overlap, with each having a distinct set of RNases in addition to a core set of enzymes that is highly conserved across the bacterial spectrum. In this paper, we describe what the functions performed by major RNases in these two bacteria, and how the evolutionary space between them can be described by two opposing gradients of enzymes that fade out and fade in, respectively, as one walks across the phylogenetic tree from E. coli to B. subtilis. [ABSTRACT FROM AUTHOR]

Metastatic progression, which begins with the invasion and migration of tumor cells from a primary tumor, marks a major turning point in the evolution of cancer. Indeed, it eventually leads to the formation of secondary tumors, the metastases, which are very often responsible for the patient's death. Understanding the mechanisms controlling the different steps of this process, as well as those explaining the fundamental phenomenon of organotropism (i.e. the distribution of metastases in distant organs by a non-random and tumor-specific process), is essential to define new innovative therapeutic solutions. In this review paper, we will present how biomechanics is an essential element to this understanding, and will emphasize the importance of this orthogonal and promising angle of study as well as our laboratory's focus on the late stages of dissemination, arrest and extravasation of circulating cancer cells and factors secreted by the primary tumor such as extracellular vesicles. [ABSTRACT FROM AUTHOR]

As part of an ongoing survey of scorpion diversity in Colima, Mexico, the isolated mountain Cerro Grande, part of the Biosphere Reserve Sierra de Manantlán, was investigated. Centruroides possanii sp. nov., the fifth species of the genus from the state, was discovered during fieldwork in the massif and is described in the present paper. Physiographical and climatic features of Cerro Grande may restrict the range of this new species; thus, we hypothesized that it may be a microendemic species that requires priority conservation. The new species is not assigned to any Centruroides species group recognized because some of its morphological features do not fit the current diagnosis of any of these groups, and these different groups are non-monophyletic and consequently ill-diagnosed. The new species is profusely illustrated, particularly the hemispermatophore. A distribution map is presented along with the other two more common species distributed in Colima. Because only indirect data on the potency of its venom is available, the medical importance of this new species described here is yet to be known. [ABSTRACT FROM AUTHOR]

For decades, human activities have gradually destroyed the natural habitats of wild grapevine, Vitis vinifera L. subsp. sylvestris (Gmelin) Hegi, and nowadays this species is endangered in southern Europe. In this paper, 94 populations of this species have been localized and characterized in the Andalusian region in the Iberian Peninsula between 1989 and 2013. Location, ecological aspects, and sanitary characteristics are described. Must properties and in vitro tolerance to calcareous conditions were also checked. The paper also contains a global description of female and male individuals. Two hundred individuals from six river basin populations have been sampled, and their genetic structure analyzed by using 25 nuclear microsatellites loci to investigate the gene diversity of wild grape populations in Andalusia at two levels: total individuals and at river basin populations. Also, the genetic relationship of wild and cultivated accessions has been tested. Wild grapevine is considered the ancestor of the cultivated varieties and should be preserved as this material could be used to start breeding programs of cultivated varieties and also to restore riverbank forests, which constitute one of the worst preserved ecosystems in the area. [ABSTRACT FROM AUTHOR]

Although scorpions have been described from China since the 19th century, it was only in the early 2000s that this fauna has seen a noticeable improvement in terms of the number and diversity of the described taxa. Some regions of China have been extensively prospected, while others remain largely unexplored. The latter is the case for the Province of Xinjiang, in the Extreme West of the country. A few contributions dealing with scorpions from this region are available, but these mainly concern representatives of the family Buthidae. In the present paper, a new species belonging to the genus Scorpiops Peters, of the family Scorpiopidae Kraepelin, is described from the Taxkorgan Natural Reserve. The description is based on one male and one female collected under stones at altitudes of 4500–4600 m. To our knowledge, this is the first species ever described from the Taxkorgan Natural Reserve and may represent an endemic element within the fauna of Xinjiang Province. [ABSTRACT FROM AUTHOR]

Morphological markers as well as two types of molecular markers, inter-sample sequence repeat (ISSR) and start codon targeted (SCoT) are suitable for species identification of the polygonati rhizoma germplasms. In this paper, we adopted these methods for the identification of rhizomes collected from 47 areas in China. Based on their morphological characters, the collected germplasms were classified into two populations, one with alternate leaf arrangement and the other with verticillate leaf arrangement, and they were comprised of five species and fourteen subgroups. Of the five species identified: Polygonatum kingianum , P. cirrhifolium , P. alternicirrhosum , and P. sibiricum belonged to one cluster, and P. cyrtonema belonged to a different cluster. According to the analysis of both ISSR and SCoT markers, all germplasms with greater genetic similarity were classified into one group. Especially, P. sibiricum and P. cirrhifolium , which shared ∼80% similarity, were clustered together, whereas the germplasms identified as P. kingianum with ∼86% similarity formed a separate clade. P. kingianum showed a much greater genetic similarity with P. cyrtonema than with P. sibiricum . The multidimensional scaling analysis further verified the accuracy and reliability of the molecular marker-based results. Thus, both morphological and molecular methods should be combined for the differentiation of germplasms such as those of polygonati rhizoma. [ABSTRACT FROM AUTHOR]

Discocyrtanus canjinjim sp. n., belonging to the family Gonyleptidae Sundevall, 1833 is described based on nineteen specimens, eleven adult males and eight adult females, collected in the Vila Bela da Santíssima Trindade, in the State of Mato Grosso, Brazil. This new species represents an endemic component for the harvestmen fauna of Chiquitano Dry Forests terrestrial eco-region, being the most occidental point of distribution of the genus, notably found in the Cerrado and the Atlantic Forest. The new species is characterized by femur IV swollen with the same length of dorsal scutum, trochanter IV with prodorsal distal apophysis as a stout hook not bifurcated, and a unique form of genitalia in the genus. This paper also includes the first identification key to the species of the genus after its revalidation. [ABSTRACT FROM AUTHOR]

Endocrine disruption is commonly thought to be restricted to a direct endocrine mode of action i.e. the perturbation of the activation of a given type of hormonal receptor by its natural ligand. Consistent with the WHO definition of an endocrine disrupter, a key issue is the “altered function(s) of the endocrine system”. Such altered functions can result from different chemical interactions, beyond agonistic or antagonistic effect at a given receptor. Based on neuroendocrine disruption by polychlorinated biphenyls and bisphenol A, this paper proposes different mechanistic paradigms that can result in adverse health effects. They are a consequence of altered endocrine function(s) secondary to chemical interaction with different steps in the physiological regulatory processes, thus accounting for a possibly indirect endocrine mode of action. [ABSTRACT FROM AUTHOR]

VIP and its receptors (VPACRs) are largely investigated in vertebrate testis, as well as their functions in the control of spermatogenesis and steroidogenesis. By contrast, a few data are available about the presence and role of VIP in the epididymis. The aim of the present paper was to investigate the localization of VIP and its receptors in the epididymis of two vertebrates: Podarcis sicula , a seasonal reproducer, and Rattus rattus , a continuous reproducer. By immunohystochemical investigation, we demonstrated for the first time that VIP and its receptors are widely represented in the epididymis of Podarcis sand Rattus ; in particular in Podarcis , we showed that during the reproductive period, as well as in Rattus , VIP and its receptors are well represented in all the epithelial cells and the connective tissue of the epididymis; by contrast, during the non-reproductive period, VIP and its receptors are represented only in the connective tissue. The possible role of the VIP/VPACR system in the control of reproduction is discussed. [ABSTRACT FROM AUTHOR]

Three plant oils ( Cymbopogon citratus , Cymbopogon martini , and Pelargonium graveolens ) were developed as EC formulations and tested for their physical stabilities. EC formulations (10EC, 20EC and 30EC) of C. citratus , C. martini and P. graveolens had emulsion stability, spontaneity property, heat and cold stability. EC formulated plant oils were screened against the major seed borne fungi of rice such as Curvularia lunata , Fusarium moniliforme , Bipolaris oryzae , and Sarocladium oryzae . The level of inhibition varied among the concentrations of EC formulations. Among the three EC formulations, that of C. citratus oil 30EC recorded 100% inhibition on the mycelial growth of test pathogens. In the blotter paper method, rice seeds treated with a formulation of C. citratus oil 30EC controlled the infection of C. lunata, F. moniliforme, B. oryzae and S. oryzae in rice seed to the tune of 66.0%, 60.4%, 66.0% and 69.1%, respectively. Seed soaking with formulation of C. citratus oil 30EC showed the highest percentage of normal seedlings, the lowest number of abnormal seedling and fresh ungerminated seeds when tested with the roll-towel method. Seed soaking with 30EC formulation of C. citratus oil increased seed germination, shoot length, root length and vigour of rice seedlings when tested with the plastic tray method. Transmission of pathogens from seed to seedling was reduced significantly by the 30EC formulation of C. citratus oil when tested with the plastic pot method. The effect of the storage life of the 30EC formulation of C. citratus oil showed that it had retained their antifungal effect till the end of the incubation period (120 days), and is able to inhibit the mycelial growth of all test pathogens to the 100% level. [ABSTRACT FROM AUTHOR]

Metamorphosis was a key innovation in insect evolution, wherein the individual acquires characteristic adult features and stops molting during postembryonic development. The ancestral metamorphosis mode was hemimetaboly, in which the embryogenesis gives rise to a first instar nymph with the essential adult body structure. The nymphs grow gradually and the final molt to the adult stage completes the formation of functional genitalia and wings. The metamorphosis mode known as holometaboly emerged from hemimetaboly, which is characterized by embryogenesis that produces a larva with a body form that may be substantially different from that of the adult. The larva grows through various stages until molting to the pupal stage, which bridges the gap between the morphologically divergent larva and that of the winged and reproductively competent adult. In the hemimetabolan and holometabolan modes, metamorphosis is regulated by two hormones: the juvenile hormone (JH) and the ecdysone, plus its biologically active derivative, 20-hydroxyecdysone (20E). 20E is a steroid, and its main role is to promote the successive molts, including the metamorphic one, whereas JH is a terpenoid, whose function is to repress metamorphosis [1]. The action of these hormones is underpinned by the mechanisms that transduce the hormonal signal through a pathway of gene activation. The 20E signaling pathway was first described in the 1990s [2] , whereas the most important details of the JH pathway were unveiled recently. Important components of the JH signaling pathway are the JH receptor, which is the basic helix–loop–helix-Per-ARNT-Sim (bHLH-PAS) protein known as methoprene tolerant (Met), to which JH binds, as unveiled by Jindra's group in the 2010 decade. Another important component is Taiman, also a bHLH-PAS protein that plays the role of co-receptor. Finally, the transcription factor Krüppel homolog 1 (Kr-h1) is the main transducer of the antimetamorphic signal of JH [1]. Kr-h1 was discovered in Drosophila melanogaster as a gene with structural similarity to the segmentation gene Krüppel , with which it shares the zinc-finger motifs and amino acid spacers connecting them. The first evidence that connected Kr-h1 and JH was also obtained in D. melanogaster. In this fly, the adult abdominal epidermis derives from larval histoblasts, which start proliferating after puparium formation. The experiments of Ashburner in 1970 showed that administration of JH prior to the prepupal stage prevents the normal differentiation of the abdominal epidermis, and the bristles that should be formed in the adult are shorter or lacking. In 2008, the experiments of Minakuchi and coworkers indicated that Kr-h1 expressed ectopically in the abdominal epidermis during metamorphosis of D. melanogaster also resulted in missing or short bristles, thereby suggesting that Kr-h1 mediates the antimetamorphic action of JH. New experiments of Minakuchi and coworkers carried out in the beetle Tribolium castaneum in 2009 showed that RNAi depletion of Kr-h1 in young larvae caused a precocious larval–pupal transformation, providing clear evidence that Kr-h1 represses metamorphosis and works downstream from Met in the JH signaling pathway. The antimetamorphic action of Kr-h1 was generalized to hemimetabolans in two parallel papers published in 2011 and conducted, respectively, in the cockroach Blattella germanica by Lozano and Belles, and the bugs Pyrrhocoris apterus and Rhodnius prolixus by Konopová and coworkers. In these two studies, RNAi experiments showed that Kr-h1 depletion in nymphs in the penultimate or antepenultimate nymphal stage triggers precocious metamorphosis [1] (Fig. 1 A). E93 is an early gene in the ecdysone signaling cascade that is specifically expressed in late prepupae of D. melanogaster. As shown by the groups of Thummel and Baehrecke in the 1990 decade, the gene encodes for a protein with RHF domains significantly similar to pipsqueak motifs, which was found to be a key player in the degeneration process of the salivary glands during D. melanogaster metamorphosis. However, the action of E93 in metamorphosis is not restricted to the regulation of degeneration processes, given that it also plays morphogenetic roles. In 2012 Mou and coworkers observed that E93 is widely expressed in adult cells of the pupa of D. melanogaster , where it is required for patterning processes. Studying the induction of the Distal-less (Dll) gene within bract cells of the pupal leg using epidermal growth factor (EGF) receptor signaling, Mou and coworkers found that E93 causes Dll to become responsive to EGF receptor signaling, thus indicating that E93 is both necessary and sufficient for determining this switch. These results suggested that E93 controls the responsiveness of many other target genes and that it is generally required for patterning during metamorphosis. Subsequent RNAi experiments reported by Ureña and coworkers in 2014 showed that E93-depleted D. melanogaster larvae are able to pupate but die at the end of the pupal stage. In T. castaneum , E93 depletion by RNAi prevented the pupal–adult transition, resulting in the formation of a supernumerary second pupa. Similar results were obtained in the cockroach B. germanica , where E93 depletion in nymphs prevented the nymphal–adult transition, giving rise to repeated supernumerary nymphal instars (Fig. 1 B). The same year, Belles and Santos showed that the expression of E93 in juvenile nymphs of B. germanica is inhibited by the transcription factor Kr-h1, thus uncovering the essential mechanism by which JH represses metamorphosis, which was named MEKRE93 pathway [3]. The observation that Kr-h1 represses E93 expression led to propose the MEKRE93 pathway as the essential axis regulating insect metamorphosis. Accordingly, in nymph–nymph transitions, JH acts through its receptor Met-Taiman to induce the expression of Kr-h1 , while Kr-h1 represses the expression of E93. In contrast, the decline of JH production in the final juvenile stage interrupts Kr-h1 expression, E93 becomes de-repressed, thus triggering adult morphogenesis (Fig. 2 A) (Belles and Santos, 2014). RNAi experiments in B. germanica by the same authors also revealed that E93 depletion increases Kr-h1 expression, thus indicating that Kr-h1 and E93 are reciprocally repressed. The inhibitory action of Kr-h1 upon E93 expression was corroborated two years later in the holometabolan T. castaneum by Ureña and coworkers, which extended the MEKRE93 pathway framework to holometabolan metamorphosis. The main difference between the hemimetabolan and holometabolan metamorphoses is the regulation and function of the Broad complex (BR-C) zinc-finger transcription factors. In hemimetabolan species, BR-C is mainly involved in promoting the growth of wing primordia. For example, this was shown in B. germanica by Huang and coworkers in 2013, who additionally reported that BR-C expression is induced by JH and Kr-h1 during juvenile stages. One year later, Ureña and coworkers found that BR-C is repressed by E93 in the metamorphic transition. Furthermore, RNAi studies made in 2019 by the group of Mito and Noji in the cricket Gryllus bimaculatus , a hemimetabolan species, confirmed the mentioned interactions, and additionally discovered that BR-C and Kr-h1 are reciprocally activated. In sharp contrast, and as shown mainly by the group of Riddiford in the decade of 1990, BR-C triggers the formation of the pupal stage in holometabolan species, where JH inhibits the expression of BR-C during larval stages and stimulates BR-C expression after pupal commitment (Fig. 2 B). In 2019, Chafino and co-workers showed that E93 is involved in triggering the pupal stage, as it promotes BR-C expression in T. castaneum. The whole data indicates that the MEKRE93 pathway is conserved in the holometabolan species, which added the E93/BR-C interaction loop to the ancestral (hemimetabolan) pathway during the evolutionary transition from hemimetaboly to holometaboly (Fig. 2 C). [ABSTRACT FROM AUTHOR]

The molecular techniques are the standard tool for the study of the taxonomic position and phylogenetic affinities of the lymnaeid genus Radix Montfort, 1810, and the majority of the European representatives of this taxon have been studied in this respect. However, a plethora of nominal species of Radix described from Northern Asia (Siberia and the Russian Far East) are still characterized only morphologically, raising some doubts concerning their validity. In this paper, we present the triple (morphological, molecular, and zoogeographical) evidence that there is at least one endemic species of Radix , Radix dolgini (Gundrizer and Starobogatov, 1979), widely distributed in Siberia and Western Mongolia. Phylogenetically, it is a sister species to the European R . labiata (Rossmaessler, 1835) [= R . peregra auct.], and their common ancestor most probably lived in the Pliocene, nearly 3.25 Myr ago. Our results assume the existence of an extended dispersal barrier for freshwater hydrobionts between Europe and Siberia in the Late Pliocene that may be important for biogeographical explanations. Three other nominal Siberian species of Radix : R . kurejkae (Gundrizer and Starobogatov, 1979), R . gundrizeri (Kruglov and Starobogatov, 1983), and R . ulaganica (Kruglov and Starobogatov, 1983) proved to be the junior synonyms of R . dolgini . [ABSTRACT FROM AUTHOR]

Résumé L’article engage une investigation historique sur l’origine de l’expression « biologie synthétique » dans le but d’en dégager les principales composantes philosophiques. Les résultats de cette analyse sont ensuite utilisés pour étendre l’examen au terme d’« homme synthétique ». On montre ainsi que les deux notions comportent l’affirmation d’une conviction philosophique commune qui peut se résumer de la façon suivante : « la biologie est de la technologie ». L’analyse de cette affirmation permet de distinguer nettement deux notions qui sont généralement confondues dans la littérature transhumaniste : celle d’homme synthétique et celle d’homme nouveau. Les conséquences de cette distinction cruciale sont discutées. In this paper, we propose an historical survey of the expression “synthetic biology” in order to identify its main philosophical components. The result of the analysis is then used to investigate the meaning of the notion of “synthetic man”. It is shown that both notions share a common philosophical background that can be summed up by the short but meaningful assertion: “biology is technology”. The analysis allows us to distinguish two notions that are often confused in transhumanist literature: the notion of synthetic man and the notion of renewed man. The consequences of this crucial distinction are discussed. [ABSTRACT FROM AUTHOR]

Résumé Cet article porte sur les liens entre éthique et science, au cours de la période 1974–2014, qui est un moment de grandes avancées des sciences de la vie. Dans un premier temps (1974–1994), l’essor d’une bioéthique d’inspiration philosophique, formulée en termes de grands principes , soutient la recherche, et les savants, appelés à se conduire de façon responsable , pensent pouvoir converger vers des solutions irréprochables et consensuelles aux problèmes posés par les progrès de la science. Dans un second temps (1994–2014), cependant, avec l’entrée dans le jeu bioéthique des sciences humaines et sociales, les pratiques normatives observées sur le terrain révèlent que les attitudes dites responsables sont compatibles avec une pluralité de convictions éthiques divergentes . Alors, les politiques rétablissent un ordre, la loi court-circuite la réflexion éthique , et, loin de rester les sages que l’on croyait porteurs des meilleures solutions, les chercheurs sont accusés d’être irresponsables lorsqu’ils manquent d’honnêteté intellectuelle. The paper is about the links between ethics and science, at a time (1974–2014) when the life sciences expanded rapidly. First (1974–1994), the development of a principlist ethics, set out by philosophers, sustained the research, and the scientists, expected to behave responsibly, felt like they could easily converge towards impeccable and consensual solutions to any problem arising from scientific innovations. Later on (1994–2014), however, while yielding ground to social sciences and ground work, bioethics took an empirical turn; then it became clear that behaving responsibly was compatible with a plurality of divergent normative convictions. Ethics crumbled. Local or national policies restored order, so-called bioethical laws short-circuited ethical reflection. And far from being respected as the wise men, apt to recommend the very best solutions to problems raised by new scientific advances, researchers happened to be deemed irresponsible , as some of them were suspected of lacking intellectual integrity. [ABSTRACT FROM AUTHOR]

In this paper, I examine some important metaphysical lessons that are often presented as derived from two new scientific disciplines: synthetic biology and neuroscience. I analyse four of them: the nature of life, the existence of a soul (the mind-body problem), personhood, and free will. Many caveats are in order, and each ‘advance’ or each case should be assessed for itself. I conclude that a main lesson can nevertheless be learned: in conjunction with modern science, neuroscience and synthetic biology allow us to enrich old metaphysical debates, to deepen and even renew them. In particular, it becomes less and less plausible to consider life, mind, person, and agency as non-natural or non-physical entities. [ABSTRACT FROM AUTHOR]

At the Paris Colloquium held forty years ago, and which this paper celebrates, the issue of psychosurgery had not been tackled yet. At that time psychosurgery was tainted by the controversial history of lobotomy and leucotomy. Supporters of psychosurgery at the time of the Colloquium were preparing their fourth International Conference, which was held in Madrid the following year. This represented a key characteristic of the collective, institutional and symbolic action of psychosurgery practitioners. At the end of the seventies, their strategy changed as noted below. Furthermore, we focus on the special importance of the results presented and commented on by psychosurgery supporters, including its conception and classification throughout the rhetoric historically involved (its supposed ventriloquism, its persuasive strength). Based on this view, we suggest a critical reflection encompassing old and new psychosurgery, while questioning the value of new rhetorical devices for the assessment and presentation of psychosurgery results after the surge of Deep Brain Stimulation. [ABSTRACT FROM AUTHOR]

In 1959, Jacques Monod wrote a manuscript entitled Cybernétique enzymatique [Enzymatic cybernetics]. Never published, this unpublished manuscript presents a synthesis of how Monod interpreted enzymatic adaptation just before the publication of the famous papers of the 1960s on the operon. In addition, Monod offers an example of a philosophy of biology immersed in scientific investigation. Monod's philosophical thoughts are classified into two categories, methodological and ontological. On the methodological side, Monod explicitly hints at his preferences regarding the scientific method in general: hypothetical-deductive method, and use of theoretical models. He also makes heuristic proposals regarding molecular biology: the need to analyse the phenomena in question at the level of individual cells, and the dual aspect of all biological explanation, functional and evolutionary. Ontological issues deal with the notions of information and genetic determinism, “cellular memory”, the irrelevance of the notion of “living matter”, and the usefulness of a cybernetic comprehension of molecular biology. [ABSTRACT FROM AUTHOR]

In his famous book Le hasard et la nécessité (1970), Monod claims that natural evolution is based on the interplay between chance and necessity bringing about adaptive evolutionary change. This article addresses a set of related questions about Monod's conception of chance: what does he mean when he uses the term “chance”? Does he invoke one or many different concepts of chance? What are the implications of his conception about the issue of the deterministic or indeterministic nature of the biological world? Is Monod's view of what chance is relevant in contemporary biology? This paper, structured by these four questions, aims at providing a synthetic study of the way Monod conceptualizes chance, particularly highlighting the metaphysical and epistemological implications of his conception and its value in biology today. [ABSTRACT FROM AUTHOR]

Exploiting the annotation of the western clawed frog Silurana tropicalis genome, we identified a new metallothionein (MT) gene, exhibiting all the features to be considered an active gene, but with an atypical coding region, showing only 17 cysteine residues instead of the canonical 20 cysteines of vertebrate metallothioneins and two anomalous cysteine triplets. However, the presence of a gene in the genome does not ensure its effective expression. By using conventional and Real-Time PCR analyses, we demonstrated that this atypical MT is constitutively expressed throughout the life cycle of the African clawed frog Xenopus laevis ; moreover, this gene is highly expressed in the adult liver, the major site of MT expression and synthesis in vertebrates. To our knowledge, the X. laevis MT described in this paper is the first sequence of a vertebrate MT showing only 17 cysteine residues, arranged in two Cys–Cys–Cys motifs. Phylogenetic analyses also demonstrated that the atypical X. laevis MT merges in the anuran clade, but is the most derived sequence among tetrapods MTs. Finally, Tajima's Relative Rate Test suggested a different evolutionary rate between the canonical X. laevis MT and this novel isoform. [ABSTRACT FROM AUTHOR]

In this paper, a delayed predator–prey model with Hassell–Varley-type functional response is investigated. By choosing the delay as a bifurcation parameter and analyzing the locations on the complex plane of the roots of the associated characteristic equation, the existence of a bifurcation parameter point is determined. It is found that a Hopf bifurcation occurs when the parameter τ passes through a series of critical values. The direction and the stability of Hopf bifurcation periodic solutions are determined by using the normal form theory and the center manifold theorem due to Faria and Maglhalaes (1995). In addition, using a global Hopf bifurcation result of Wu (1998) for functional differential equations, we show the global existence of periodic solutions. Some numerical simulations are presented to substantiate the analytical results. Finally, some biological explanations and the main conclusions are included. [ABSTRACT FROM AUTHOR]

The recently erected cestode order Diphyllobothriidea is unique among all tapeworm orders in that its species infect all major groups of tetrapods, including man. In the present paper, the vitellogenesis of representatives of all three currently recognized families of this order was evaluated, based on ultrastructural (transmission electron microscopy) and cytochemical (detection of glycogen) observations. Vitelline follicles of all taxa studied, i.e. Cephalochlamys namaquensis from clawed frogs ( Xenopus ), Duthiersia expansa from monitors ( Varanus ) and Schistocephalus solidus that matures in fish-eating birds, contain vitelline cells at various stages of development and interstitial cells. Developing vitellocytes are characterized by the presence of mitochondria, granular endoplasmic reticulum and Golgi complexes involved in the synthesis of shell globules and formation of shell globule clusters. Mature vitellocytes contain lipids and glycogen in different proportions. The most significant differences among the three diphyllobothriidean families were found in the presence or absence of lamellar bodies. Variations of vitelline clusters morphology and types of lipid droplets are described and discussed in relation to the presumed evolutionary history of diphyllobothriideans, which belong to the most basal cestode groups. [ABSTRACT FROM AUTHOR]

The aims of this paper were (i) to define how contrasting land uses affected plant biodiversity in Mediterranean agro-silvo-pastoral-systems across a gradient of disturbance regimes: cork oak forests, secondary grasslands, hay crops, grass covered vineyards, tilled vineyards; (ii) to determine whether these patterns mirrored those of below-ground microorganisms and whether the components of γ-diversity followed a similar model. The disturbance regimes affected plant assemblage composition. Species richness decreased with increasing land use intensity, the Shannon index showed the highest values in grasslands and hay crops. Plant assemblage composition patterns mirrored those of Basidiomycota and Ascomycota . Richness in Basidiomycota , denitrifying bacteria and microbial biomass showed the same trend as that observed for vascular plant richness. The Shannon index pattern of below-ground microorganisms was different from that of plants. The plant γ-diversity component model weakly mirrored those of Ascomycota . Patchy diversity patterns suggest that the maintenance of contrasting land uses associated with different productions typical of agro-silvo-pastoral-systems can guarantee the conservation of biodiversity. [ABSTRACT FROM AUTHOR]

Insects, as small animals of frequent and easy access to humans, at least under their non-flying larval stages, have always been of interest to our species. The interest has probably been nutritional, but also naturalistic and symbolic. Many aspects of insects' biology are of high symbolic potential, among which biodiversity, metamorphosis or flight. These three creative attributes of the insect orders, over the mammalian order at least–the self or reference class of human life–, probably induced early interests in human societies. This interest is indicated by folk classification of insects in some indigene cultures of northern America or central Africa [1]. Representation of insects in paleolithic art is scarce but existing; one of the earliest attested records could be that of "the buprestid" of Arcy-sur-Cure, revised as a ground beetle–carabid–(Magdalenian III, ≈ 15000 years BP), or that of "the grasshopper" of Enlène [2]. The first is sculpted in lignite and could have served as a shamanic representation, while the latter is more obviously naturalistic in nature, and carved on bone. The more recently discovered Chauvet cave might contain insect representations (a "butterfly" or a many-legged animal), but no attested insects yet. Similarly, no insect mention come yet from Sulawesi caves (late Mousterian, < 30,000 years BP). Neolithic representations are much more numerous, as exemplified by bee hunting and bee rearing in Iberic or Egyptian parietal and monumental arts. This trend culminated in Egyptian jewellery and its quasi-industrial representations of scarab or dung beetles. Noteworthy, most prehistoric representation of insects lie on coleoptera and Hymenoptera, and associated with symbolic features linked to colour, strength (beetles), metamorphosis (all) or social and utility behaviours (bees, ants). Aristotle himself did not clearly recognize aphids as a group, as the ancient Greek word ψυλλίδα did not differentiate aphids and psyllids. Many mentions however, on the reproduction of such insects, for example, show that he was talking of aphids. In line with these historical roots, insects have been associated with far eastern or Christian society arts [3] — in contrast, Islamic and Jewish imaging or alimentary taboos having banned them from visible representations in middle eastern societies. A previous review on the subject gives an excellent outline of our matter, restricted to European painting [4]. I will here sketch a variant perspective, trying to uncover a hitherto hidden monument of cultural entomology, with the case study of the representation of aphids (Hemiptera: Aphididae) in various arts and all periods of history. Our purpose is to draw a reflexive perspective on what such invisible insects, through their invisibility, tell us of their representation in artists' minds, and more generally in any human mind (being he a reader, a writer, a watcher, an actor, or in any position of the artistic universe). The first and archetypal position to be quoted in my survey of invisible insects is the detail aphid. This position of a subject, the detail, have been analysed thoroughly in the history of arts [5]. It reflects both scientific and artistic mastery end precision (it is painted because it exists), and a position of power of the painter who is freely choosing low signification or even forbidden or non-codified subjects due to the act of freedom of the artist (and art factories, often specialized in such very specific matters); I paint it because I want/know it. This is characteristic of the Flemish and Dutch renaissance, as visible in the Bouquet of flowers in a vase by Jan velvet Brueghel the Elder (Fig. 1). In contrast to many of its fellow insects, cricket, coleoptera, syrphid, the aphid is extremely difficult to localize (Fig. 1 A), and needs an intensive focus on its lily host-plant to be seen (Fig. 1 B). However, in spite of its minute size, it is precisely depicted, and the crescent-marked lily aphid was recognized by expert aphidologists (Colin Favret, pers. comm.). A non-expert comparison between object and subject (Fig. 1 B,C,D), be it living (1 C) or mounted (1D) is edifying and informs us on the naturalistic and observational abilities of the painter(s). As one may imagine, such identification of aphids in European classical painting is extremely difficult and has been only found on three occasions and with the help of the G-art Gigapixel project, apart from Fig. 1 : in another still life by velvet Brueghel, Flowers in a Vase displaying at the Antwerp museum of fine arts, and in a third Chat renversant un vase de fleurs by Abraham Mignon, Museum of Fine Arts, Lyon. All Dutch painters. One easy case of naturalistic aphid lie in the paintings of Maria Sibylla Meriam, a painter and entomologist of the seventieth century who has painted aphids in numerous works, and both entitled some of her paintings with the word, and depicted the whole aphid ecosystem including all trophic levels in the global picture (Rode akelei met bladwesp en bladluis , 1684). One important item in our quest is the topos of the female aphid (and eventually superfemale aphid). It probably did not start with Charles Bonnet, but at least has fully expanded after him. This talented Swiss student of Réaumur discovered, described, and demonstrated parthenogenesis in what could be called one of the first modern scientific papers in biology, its Traité d'entomologie (1745). This signed a series of quasi-quotes all over the following centuries, exemplifying the importance of this reproductive trait in biology, as well as the importance of aphids as a model for this trait: this started by a pejorative citation of Eugène Delacroix in a letter to a friend in 1830 ("What a pity that such brilliant mind and man has lost his time and eyes for understanding the venial sin of such hideous animals"), followed by a real tribute to parthenogenesis in the masterpiece of Simone de Beauvoir, Le deuxième sexe (Volume 1, Chapter 1, "The data of Biology"). One may also quote in this very context the interesting parallel, made by the contemporary art blog Quadrivia, between parthenogenesis and the codified representation of "Sainte Anne trinitaire" in the European religious sculpture of the late Middle Ages (https://quadriv.wordpress.com/2011/06/10/jesus-aphids-and-parthenogenesis/). The sculptural code of Ste Anne consisted in a triptychal representation of Virgin Mary, her mother Anne, and child Jesus in a strange character proportionality of adult (Anne), child-adult (Mary) and child-child (Jesus). This invasion of the female-only character over the Holy Trinity was increasingly popular in central Europe from the fortieth to the sixtieth century (https://fr.wikipedia.org/wiki/Sainte%5fAnne%5ftrinitaire), and was only stopped by a specific canonical law codifying the Marial cult, or hyperdulia, within the Council of Trento (1542–1563). Although no aphid is represented in such topoi, of course, the parallel between parthenogenesis and viviparity, somehow unique to aphids, and the mystery of immaculate conception ought to be underlined. Already exemplified by Eugene Delacroix, cited above, the recurrent and frequent topos of the evil aphid has been used many times in French literature. Victor Hugo listed the vile aphid among a list of biological fearsome fellows (Les Contemplations , T3 L6 26, p. 467 as appears in the Frantext database). However, the complimentary figure of the humble aphid is also present in post-ninetieth-century occurrences, typically shown in Maurice Carême's poem entitled Le Puceron. Coming to modern art, the appearance of aphids tends to explode, and I will only quote two examples. One is what could be called the surrealistic oulipian aphid by Boris Vian (Fig. 2), the other being the situationist aphid of the musical theme of the Polish artist Duy Gebord in the well-named Mildew album (https://duygebord.bandcamp.com/album/mildew). The former merits a short outline, as it is emblematic of the mosaic Carollian style of Boris Vian (Les Fourmis , Fig. 2 A). The prose starts as a very standard description of a explicitly boring subject, to fall out into the final blackhole of Oulipian fantasy (which translates as "The rearing of the Tyrolian 'gnatlet'or the milking of woolly aphids"). The induced image explicitly (again) looks as Fig. 2 A, driving the reader in a universe of gentle and poetic madness typical of Vian's prose. It should be noted that the French mouchetis tyrolien (translated as Tyrolian gnatlet) does not refer, as it seems through subtle juxtaposition, to an insect: instead it refers to an industrial painting technique, also typical of the universe of engineer Boris Vian, who started as fonctionnaire of the French normalization agency AFNOR (as did Albert Einstein with the Swiss patent agency)... We hope that our short survey of a hitherto boring subject has driven the reader on the wild side of the history of arts and sciences, and that the final references will allow him to escape even more, at night, from its truly exciting daytime highways of insect science. This compendium and conference is part of an ongoing project, involving the aphid BAPOA community for data collection, and partially published by Encyclopaphid [6]. The full corpus contains more than 100 entries and the present outline is thus only the hidden part of the iceberg, to be fully published soon. This conference is quoted in the CNRS repository HAL as: https://hal.archives-ouvertes.fr/hal-02069668. [ABSTRACT FROM AUTHOR]