Other Vertebrates (other + vertebrate)

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  • other vertebrate species

  • Selected Abstracts

    Chondrichthyans from a Cenomanian (Late Cretaceous) bonebed, Saskatchewan, Canada

    PALAEONTOLOGY, Issue 4 2010
    Abstract:, Acid preparation of samples of a bonebed from the Cenomanian of central Canada yielded several thousand well-preserved chondrichthyan teeth, in addition to numerous other vertebrate remains. Teeth and other remains of one species of chimaeroid, one species of hybodont shark, three species of Ptychodus, 10 species of neoselachian sharks and two species of batoid were recorded. The family Archaeolamnidae fam. nov., genera Meristodonoides gen. nov. and Telodontaspis gen. nov. and species Ptychodus rhombodus sp. nov., Telodontaspis agassizensis gen et sp. nov., Eostriatolamia paucicorrugata sp. nov., Roulletia canadensis sp. nov., Cretorectolobus robustus sp. nov. and Orectoloboides angulatus sp. nov. are described. Status of the genus Palaeoanacorax and the species Cretoxyrhina denticulata, Squalicorax curvatus and ,Rhinobatos'incertus are discussed, and reconstructed dentitions of Archaeolamna and Roulletia presented. The fauna is of low diversity and dominated by active hunters, with many species apparently endemic to the northern Western Interior Seaway. [source]

    Wnt6 expression in epidermis and epithelial tissues during Xenopus organogenesis

    Danielle L. Lavery
    Abstract Here, we report the localization within embryonic tissues of xWnt6 protein; together with the temporal and spatial expression of Xenopus laevis Wnt6 mRNA. Wnt6 expression in Xenopus embryos is low until later stages of neurulation, when it is predominantly found in the surface ectoderm. Wnt6 expression increases during early organogenesis in the epidermis overlaying several developing organs, including the eye, heart, and pronephros. At later stages of development, Wnt6 mRNA and protein generally localize in epithelial tissues and specifically within the epithelial tissues of these developing organs. Wnt6 localization correlates closely with sites of both epithelial to mesenchymal transformations and mesenchymal to epithelial transformations. Xenopus Wnt6 sequence and its expression pattern are highly conserved with other vertebrates. Xenopus embryos, therefore, provide an excellent model system for investigating the function of vertebrate Wnt6 in organ development and regulation of tissue architecture. Developmental Dynamics 237:768,779, 2008. © 2008 Wiley-Liss, Inc. [source]

    Characterization of the plasticity-related gene, Arc, in the frog brain

    Lisa A. Mangiamele
    Abstract In mammals, expression of the immediate early gene Arc/Arg3.1 in the brain is induced by exposure to novel environments, reception of sensory stimuli, and production of learned behaviors, suggesting a potentially important role in neural and behavioral plasticity. To date, Arc has only been characterized in a few species of mammals and birds, which limits our ability to understand its role in modifying behavior. To begin to address this gap, we identified Arc in two frog species, Xenopus tropicalis and Physalaemus pustulosus, and characterized its expression in the brain of P. pustulosus. We found that the predicted protein for frog Arc shared 60% sequence similarity with Arc in other vertebrates, and we observed high Arc expression in the forebrain, but not the midbrain or hindbrain, of female túngara frogs sacrificed at breeding ponds. We also examined the time-course of Arc induction in the medial pallium, the homologue of the mammalian hippocampus, in response to a recording of a P. pustulosus mating chorus and found that accumulation of Arc mRNA peaked 0.75 h following stimulus onset. We found that the mating chorus also induced Arc expression in the lateral and ventral pallia and the medial septum, but not in the striatum, hypothalamus, or auditory midbrain. Finally, we examined acoustically induced Arc expression in response to different types of mating calls and found that Arc expression levels in the pallium and septum did not vary with the biological relevance or acoustic complexity of the signal. © 2010 Wiley Periodicals, Inc. Develop Neurobiol 70: 813,825, 2010 [source]

    Hippocampal lesions impair spatial memory performance, but not song,A developmental study of independent memory systems in the zebra finch

    David J. Bailey
    Abstract Songbirds demonstrate song- and spatial-learning, forms of memory that appear distinct in formal characteristics and fitting the descriptions and criteria of procedural and episodic-like memory function, respectively. As in other vertebrates, the neural pathways underlying these forms of memory may also be dissociable, and include the corresponding song circuit and hippocampus (HP). Whether (or not) these two memory systems interact is unknown. Interestingly, the HP distinguishes itself as a site of immediate early gene expression in response to song and as a site of estrogen synthesis, a steroid involved in song learning. Thus, an interaction between these memory systems and their anatomical substrates appears reasonable to hypothesize, particularly during development. To test this idea, juvenile male or female zebra finches received chemical lesions of the HP at various points during song learning, as did adults. Song structure, singing behavior, song preference, and spatial memory were tested in adulthood. Although lesions of the HP severely compromised HP-dependent spatial memory function across all ages and in both sexes, we were unable to detect any effects of HP lesions on song learning, singing, or song structure in males. Interestingly, females lesioned as adults, but not as juveniles, did lose the characteristic preference for their father's song. Since compromise of the neural circuits that subserve episodic-like memory does very little (if anything) to affect procedural-like (song learning) memory, we conclude that these memory systems and their anatomical substrates are well dissociated in the developing male zebra finch. © 2009 Wiley Periodicals, Inc. Develop Neurobiol 2009 [source]

    Seasonal plasticity of brain aromatase mRNA expression in glia: Divergence across sex and vocal phenotypes

    Paul M. Forlano
    Abstract Although teleost fishes have the highest levels of brain aromatase (estrogen synthase) compared to other vertebrates, little is known of its regulation and function in specific brain areas. Previously, we characterized the distribution of aromatase in the brain of midshipman fish, a model system for identifying the neural and endocrine basis of vocal-acoustic communication and alternative male reproductive tactics. Here, we quantified seasonal changes in brain aromatase mRNA expression in the inter- and intrasexually dimorphic sonic motor nucleus (SMN) and in the preoptic area (POA) in males and females in relation to seasonal changes in circulating steroid hormone levels and reproductive behaviors. Aromatase mRNA expression was compared within each sex throughout non-reproductive, pre-nesting, and nesting periods as well as between sexes within each season. Intrasexual (male) differences were also compared within the nesting period. Females had higher mRNA levels in the pre-nesting period when their steroid levels peaked, while acoustically courting (type I) males had highest expression during the nesting period when their steroid levels peaked. Females had significantly higher levels of expression than type I males in all brain areas, but only during the pre-nesting period. During the nesting period, non-courting type II males had significantly higher levels of aromatase mRNA in the SMN but equivalent levels in the POA compared to type I males and females. These results demonstrate seasonal and sex differences in brain aromatase mRNA expression in a teleost fish and suggest a role for aromatase in the expression of vocal-acoustic and alternative male reproductive phenotypes. © 2005 Wiley Periodicals, Inc. J. Neurobiol, 2005 [source]

    Burying beetle Nicrophorus investigator reproduction on Pacific salmon carcasses

    M. D. Hocking
    Abstract., 1.,In many undisturbed watersheds along the Pacific Rim, anadromous salmon (Oncorhynchus spp.) provide a predictable source of carrion to the riparian zone, largely due to horizontal transfer of salmon carcasses by bears (Ursus spp.) and other vertebrates. 2.,Burying beetles are important members of the north-temperate carrion fauna, and may utilise salmon carcasses and remnants for breeding. In this study, isotopic and observational data are reported that demonstrate previously unrecognised Nicrophorus investigator (Zetterstedt) reproduction on large salmon carcasses from five watersheds in coastal British Columbia. 3.,Stable isotope signatures (,15N and ,13C) of adult beetles collected in autumn indicate a diet of salmon origin in all but one individual from all watersheds, suggesting that this beetle,salmon association is widespread. Comparison of autumn isotope signatures to individuals collected randomly in summer suggests that isotope signatures represent the larval carrion source from the previous autumn rather than immediate adult diet. 4.,In a survey of N. investigator use of salmon carcasses from two watersheds, 35 broods were observed on chum and pink salmon carcasses, including 16 natural brood complexes containing over 100 larvae, and five ranging from 250 to 750 larvae. 5.,Overall, north-coastal populations of N. investigator breed on the rich and reliable salmon resource and may exhibit a system of communal breeding on these carcasses. This is most relevant when the dramatic reduction in salmon spawning biomass over the last century is considered. [source]

    Platypus Pou5f1 reveals the first steps in the evolution of trophectoderm differentiation and pluripotency in mammals

    Hitoshi Niwa
    SUMMARY Uterine nourishment of embryos by the placenta is a key feature of mammals. Although a variety of placenta types exist, they are all derived from the trophectoderm (TE) cell layer of the developing embryo. Egg-laying mammals (platypus and echidnas) are distinguished by a very short intrauterine embryo development, in which a simple placenta forms from TE-like cells. The Pou5f1 gene encodes a class V POU family transcription factor Oct3/4. In mice, Oct3/4 together with the highly conserved caudal -related homeobox transcription factor Cdx2, determines TE fate in pre-implantation development. In contrast to Cdx2, Pou5f1 has only been identified in eutherian mammals and marsupials, whereas, in other vertebrates, pou2 is considered to be the Pou5f1 ortholog. Here, we show that platypus and opossum genomes contain a Pou5f1 and pou2 homolog, pou2-related, indicating that these two genes are paralogues and arose by gene duplication in early mammalian evolution. In a complementation assay, we found that platypus or human Pou5f1, but not opossum or zebrafish pou2, restores self-renewal in Pou5f1 -null mouse ES cells, showing that platypus possess a fully functional Pou5f1 gene. Interestingly, we discovered that parts of one of the conserved regions (CR4) is missing from the platypus Pou5f1 promoter, suggesting that the autoregulation and reciprocal inhibition between Pou5f1 and Cdx2 evolved after the divergence of monotremes and may be linked to the development of more elaborate placental types in marsupial and eutherian mammals. [source]

    Early differentiation and migration of cranial neural crest in the opossum, Monodelphis domestica

    Janet L. Vaglia
    SUMMARY Marsupial mammals are born at a highly altricial state. Nonetheless, the neonate must be capable of considerable functional independence. Comparative studies have shown that in marsupials the morphogenesis of many structures critical to independent function are advanced relative to overall development. Many skeletal and muscular elements in the facial region show particular heterochrony. Because neural crest cells are crucial to forming and patterning much of the face, this study investigates whether the timing of cranial neural crest differentiation is also advanced. Histology and scanning electron microscopy of Monodelphis domestica embryos show that many aspects of cranial neural crest differentiation and migration are conserved in marsupials. For example, as in other vertebrates, cranial neural crest differentiates at the neural ectoderm/epidermal boundary and migrates as three major streams. However, when compared with other vertebrates, a number of timing differences exist. The onset of cranial neural crest migration is early relative to both neural tube development and somite formation in Monodelphis. First arch neural crest cell migration is particularly advanced and begins before any somites appear or regional differentiation exists in the neural tube. Our study provides the first published description of cranial neural crest differentiation and migration in marsupials and offers insight into how shifts in early developmental processes can lead to morphological change. [source]

    Cranial neural crest cell migration in the Australian lungfish, Neoceratodus forsteri

    Pierre Falck
    SUMMARY A crucial role for the cranial neural crest in head development has been established for both actinopterygian fishes and tetrapods. It has been claimed, however, that the neural crest is unimportant for head development in the Australian lungfish (Neoceratodus forsteri ,), a member of the group (Dipnoi) which is commonly considered to be the living sister group of the tetrapods. In the present study, we used scanning electron microscopy to study cranial neural crest development in the Australian lungfish. Our results, contrary to those of Kemp, show that cranial neural crest cells do emerge and migrate in the Australian lungfish in the same way as in other vertebrates, forming mandibular, hyoid, and branchial streams. The major difference is in the timing of the onset of cranial neural crest migration. It is delayed in the Australian lungfish in comparison with their living sister group the Lissamphibia. Furthermore, the delay in timing between the emergence of the hyoid and branchial crest streams is very long, indicating a steeper anterior-posterior gradient than in amphibians. We are now extending our work on lungfish head development to include experimental studies (ablation of selected streams of neural crest cells) and fate mapping (using fluoresent tracer dyes such as DiI) to document the normal fate as well as the role in head patterning of the cranial neural crest in the Australian lungfish. [source]

    Unusual stability of human neuroglobin at low pH , molecular mechanisms and biological significance

    FEBS JOURNAL, Issue 23 2009
    Paola Picotti
    Neuroglobin (Ngb) is a recently discovered globin that is predominantly expressed in the brain, retina and other nerve tissues of human and other vertebrates. Ngb has been shown to act as a neuroprotective factor, promoting neuronal survival in conditions of hypoxic,ischemic insult, such as those occurring during stroke. In this work, the conformational and functional stability of Ngb at acidic pH was analyzed, and the results were compared to those obtained with Mb. It was shown by spectroscopic and biochemical (limited proteolysis) techniques that, at pH 2.0, apoNgb is a folded and rigid protein, retaining most of the structural features that the protein displays at neutral pH. Conversely, apoMb, under the same experimental conditions of acidic pH, is essentially a random coil polypeptide. Urea-mediated denaturation studies revealed that the stability displayed by apoNgb at pH 2.0 is very similar to that of Mb at pH 7.0. Ngb also shows enhanced functional stability as compared with Mb, being capable of heme binding over a more acidic pH range than Mb. Furthermore, Ngb reversibly binds oxygen at acidic pH, with an affinity that increases as the pH is decreased. It is proposed that the acid-stable fold of Ngb depends on the particular amino acid composition of the protein polypeptide chain. The functional stability at low pH displayed by Ngb was instead shown to be related to hexacoordination of the heme group. The biological implications of the unusual acid resistance of the folding and function of Ngb are discussed. [source]

    The oxidation process of Antarctic fish hemoglobins

    FEBS JOURNAL, Issue 9 2004
    Luigi Vitagliano
    Analysis of the molecular properties of proteins extracted from organisms living under extreme conditions often highlights peculiar features. We investigated by UV-visible spectroscopy and X-ray crystallography the oxidation process, promoted by air or ferricyanide, of five hemoglobins extracted from Antarctic fishes (Notothenioidei). Spectroscopic analysis revealed that these hemoglobins share a common oxidation pathway, which shows striking differences from the oxidation processes of hemoglobins from other vertebrates. Indeed, simple exposure of these hemoglobins to air leads to the formation of a significant amount of the low-spin hexacoordinated form, denoted hemichrome. This hemichrome form, which is detected under a variety of experimental conditions, can be reversibly transformed to either carbomonoxy or deoxygenated forms with reducing agents. Interestingly, the spectra of the fully oxidized species, obtained by treating the protein with ferricyanide, show the simultaneous presence of peaks corresponding to different hexacoordinated states, the aquomet and the hemichrome. In order to assign the heme region state of the , and , chains, the air-oxidized and ferricyanide-oxidized forms of Trematomus bernacchii hemoglobin were crystallized. Crystallographic analysis revealed that these forms correspond to an ,(aquomet)-,(bishistidyl-hemichrome) state. This demonstrates that the , and , chains of Antarctic fish hemoglobins follow very different oxidation pathways. As found for Trematomus newnesi hemoglobin in a partial hemichrome state [Riccio, A., Vitagliano, L., di Prisco, G., Zagari, A. & Mazzarella, L. (2002) Proc. Natl Acad. Sci. USA99, 9801,9806], the quaternary structures of these ,(aquomet)-,(bishistidyl-hemichrome) forms are intermediate between the physiological R and T hemoglobin states. Together, these structures provide information on the general features of this intermediate state. [source]

    New school in liver development: Lessons from zebrafish,

    HEPATOLOGY, Issue 5 2009
    Jaime Chu
    There is significant overlap in the genes and pathways that control liver development and those that regulate liver regeneration, hepatic progenitor cell expansion, response to injury, and cancer. Additionally, defects in liver development may underlie some congenital and perinatal liver diseases. Thus, studying hepatogenesis is important for understanding not only how the liver forms, but also how it functions. Elegant work in mice has uncovered a host of transcription factors and signaling molecules that govern the early steps of hepatic specification; however, the inherent difficulty of studying embryogenesis in utero has driven developmental biologists to seek new systems. The rapidly developing vertebrate zebrafish is a favorite model for embryology. The power of forward genetic screens combined with live real-time imaging of development in transparent zebrafish embryos has highlighted conserved processes essential for hepatogenesis and has uncovered some exciting new players. This review presents the advantages of zebrafish for studying liver development, underscoring how studies in zebrafish and mice complement each other. In addition to their value for studying development, zebrafish models of hepatic and biliary diseases are expanding, and using these small, inexpensive embryos for drug screening has become de rigueur. Zebrafish provide a shared platform for developmental biology and translational research, offering innovative methods for studying liver development and disease. The story of hepatogenesis has something for everyone. It involves transcriptional regulation, cell-cell interaction, signaling pathways, control of cell proliferation and apoptosis, plus morphogenic processes that sculpt vasculature, parenchymal cells, and mesenchyme to form the multifaceted liver. Decades of research on liver development in mice and other vertebrates offer valuable lessons in how the multipotent endoderm is programmed to form a functional liver. Of equal importance are insights that have illuminated the mechanisms by which hepatic progenitors are activated in a damaged liver, how the adult liver regenerates, and, possibly, the basis for engineering liver cells in vitro for cell transplantation to sustain patients with liver failure. Moreover, processes that are key to liver development are often co-opted during pathogenesis. Therefore, reviewing hepatogenesis is informative for both basic and translational researchers. In this review, we bring to light the many advantages offered by the tropical freshwater vertebrate zebrafish (Danio rerio) in studying hepatogenesis. By comparing zebrafish and mice, we highlight how work in each system complements the other and emphasize novel paradigms that have been uncovered using zebrafish. Finally, we highlight exciting efforts using zebrafish to model hepatobiliary diseases. (HEPATOLOGY 2009.) [source]

    The plasticity of immunoglobulin gene systems in evolution

    Ellen Hsu
    Summary:, The mechanism of recombination-activating gene (RAG)-mediated rearrangement exists in all jawed vertebrates, but the organization and structure of immunoglobulin (Ig) genes, as they differ in fish and among fish species, reveal their capability for rapid evolution. In systems where there can exist 100 Ig loci, exon restructuring and sequence changes of the constant regions led to divergence of effector functions. Recombination among these loci created hybrid genes, the strangest of which encode variable (V) regions that function as part of secreted molecules and, as the result of an ancient translocation, are also grafted onto the T-cell receptor. Genomic changes in V-gene structure, created by RAG recombinase acting on germline recombination signal sequences, led variously to the generation of fixed receptor specificities, pseudogene templates for gene conversion, and ultimately to Ig sequences that evolved away from Ig function. The presence of so many Ig loci in fishes raises interesting questions not only as to how their regulation is achieved but also how successive whole-locus duplications are accommodated by a system whose function in other vertebrates is based on clonal antigen receptor expression. [source]

    Modelling the long-term sustainability of indigenous hunting in Manu National Park, Peru: landscape-scale management implications for Amazonia

    Taal Levi
    Summary 1. ,Widespread hunting throughout Amazonia threatens the persistence of large primates and other vertebrates. Most studies have used models of limited validity and restricted spatial and temporal scales to assess the sustainability. 2. ,We use human-demographic, game-harvest and game-census data to parameterize a spatially explicit hunting model. We explore how population growth and spread, hunting technology and effort, and source,sink dynamics impact the density of black spider monkeys Ateles chamek over time and space in the rainforests of south-eastern Peru. 3. ,In all scenarios, spider monkey populations, which are vulnerable to hunting, persist in high numbers in much of Manu National Park over the next 50 years. Nonetheless, shotguns cause much more depletion than traditional bow hunting by Matsigenka (Machiguenga) indigenous people. 4. ,Maintenance of the current indigenous lifestyle (dispersed settlements, bow hunting) is unlikely to deplete spider monkeys and, by extension, other fauna, despite rapid human population growth. This helps explain why large, pre-Colombian human populations did not drive large primates to extinction. When guns are used, however, spider monkeys quickly become depleted around even small settlements, with depletion eventually reversing the short-term harvest advantage provided by shotgun hunting. Thus, our models show that when guns are used, limits on settlement numbers can reduce total depletion. 5. ,Synthesis and applications. Our framework lets us visualize the future effects of hunting, population growth, hunting technology and settlement spread in tropical forests. In Manu Park, the continued prohibition of firearms is important for ensuring long-term hunting sustainability. A complementary policy is to negotiate limits on new settlements in return for development aid in existing settlements. The advantage of the latter approach is that settlement numbers are more easily monitored than is hunting effort or technology. Similar policies could help to reduce landscape-scale depletion of prey species in human-occupied reserves and protected areas throughout the Amazon. [source]

    Estimating deer abundance from line transect surveys of dung: sika deer in southern Scotland

    Fernanda F.C. Marques
    Summary 1Accurate and precise estimates of abundance are required for the development of management regimes for deer populations. In woodland areas, indirect dung count methods, such as the clearance plot and standing crop methods, are currently the preferred procedures to estimate deer abundance. The use of line transect methodology is likely to provide a cost-effective alternative to these methods. 2We outline a methodology based on line transect surveys of deer dung that can be used to obtain deer abundance estimates by geographical block and habitat type. Variance estimation procedures are also described. 3As an example, we applied the method to estimate sika deer Cervus nippon abundance in south Scotland. Estimates of deer defecation and length of time to dung decay were used to convert pellet group density to deer density by geographical block and habitat type. The results obtained agreed with knowledge from cull and sightings data, and the precision of the estimates was generally high. 4Relatively high sika deer densities observed in moorland areas up to 300 m from the forest edge indicated the need to encompass those areas in future surveys to avoid an underestimate of deer abundance in the region of interest. 5It is unlikely that a single method for estimating deer abundance will prove to be better under all circumstances. Direct comparisons between methods are required to evaluate thoroughly the relative merits of each of them. 6Line transect surveys of dung are becoming a widely used tool to aid management and conservation of a wide range of species. The survey methodology we outline is readily adaptable to other vertebrates that are amenable to dung survey methodology. [source]

    Targeted Expression of SHH Affects Chondrocyte Differentiation, Growth Plate Organization, and Sox9 Expression,

    Sara Tavella
    Abstract The role of Hedgehogs (Hh) in murine skeletal development was studied by overexpressing human Sonic Hedgehog (SHH) in chondrocytes of transgenic mice using the collagen II promoter/enhancer. Overexpression caused a lethal craniorachischisis with major alterations in long bones because of defects in chondrocyte differentiation. Introduction: Hedgehogs (Hhs) are a family of secreted polypeptides that play important roles in vertebrate development, controlling many critical steps of cell differentiation and patterning. Skeletal development is affected in many different ways by Hhs. Genetic defects and anomalies of Hhs signaling pathways cause severe abnormalities in the appendicular, axial, and cranial skeleton in man and other vertebrates. Materials and Methods: Genetic manipulation of mouse embryos was used to study in vivo the function of SHH in skeletal development. By DNA microinjection into pronuclei of fertilized oocytes, we have generated transgenic mice that express SHH specifically in chondrocytes using the cartilage-specific collagen II promoter/enhancer. Transgenic skeletal development was studied at different embryonic stages by histology. The expression pattern of specific chondrocyte molecules was studied by immunohistochemistry and in situ hybridization. Results: Transgenic mice died at birth with severe craniorachischisis and other skeletal defects in ribs, sternum, and long bones. Detailed analysis of long bones showed that chondrocyte differentiation was blocked at prehypertrophic stages, hindering endochondral ossification and trabecular bone formation, with specific defects in different limb segments. The growth plate was highly disorganized in the tibia and was completely absent in the femur and humerus, leading to skeletal elements entirely made of cartilage surrounded by a thin layer of bone. In this cartilage, chondrocytes maintained a columnar organization that was perpendicular to the bone longitudinal axis and directed toward its outer surface. The expression of SHH receptor, Patched-1 (Ptc1), was greatly increased in all cartilage, as well as the expression of parathyroid hormone-related protein (PTHrP) at the articular surface; while the expression of Indian Hedgehog (Ihh), another member of Hh family that controls the rate of chondrocyte maturation, was greatly reduced and restricted to the displaced chondrocyte columns. Transgenic mice also revealed the ability of SHH to upregulate the expression of Sox9, a major transcription factor implicated in chondrocyte-specific gene expression, in vivo and in vitro, acting through the proximal 6.8-kb-long Sox9 promoter. Conclusion: Transgenic mice show that continuous expression of SHH in chondrocytes interferes with cell differentiation and growth plate organization and induces high levels and diffuse expression of Sox9 in cartilaginous bones. [source]

    IMGT standardized criteria for statistical analysis of immunoglobulin V-REGION amino acid properties

    Christelle Pommié
    Abstract IMGT, the international ImMunoGeneTics information system® (http://imgt.cines.fr) is a high-quality integrated information system specializing in immunoglobulins (IG), T cell receptors (TR) and major histocompatibility complex (MHC) of human and other vertebrates. IMGT comprises IMGT/LIGM-DB, the comprehensive database of IG and TR sequences from human and other vertebrates (76,846 sequences in September 2003). In order to define the IMGT criteria necessary for standardized statistical analyses, the sequences of the IG variable regions (V-REGIONs) from productively rearranged human IG heavy (IGH) and IG light kappa (IGK) and lambda (IGL) chains were extracted from IMGT/LIGM-DB. The framework amino acid positions of 2474 V-REGIONs (1360 IGHV, 585 IGKV, 529 IGLV) were numbered according to the IMGT unique numbering. Two statistical methods (correspondence analysis and hierarchic classification) were used to analyze the 237 framework positions (80 for IGHV, 79 for IGKV, 78 for IGLV), for three properties (hydropathy, volume and chemical characteristics) of the 20 common amino acids. Results of the analyses are shown as standardized two-dimensional representations, designated as IMGT Colliers de Perles statistical profiles. They provide a characterization of the amino acid properties at each framework position of the expressed IG V-REGIONs, and a visualization of the resemblances and differences between heavy and light, and between kappa and lambda sequences. The standardized criteria defined in this paper, amino acid positions and property classes, will be useful to study the mutations and allele polymorphisms, to establish correlations between amino acids in the IG and TR protein three-dimensional structures and to extract new knowledge from V-like domains of chains, other than IG and TR, belonging to the immunoglobulin superfamily. Copyright © 2004 John Wiley & Sons, Ltd. [source]

    Larynx morphology and sound production in three species of Testudinidae

    Roberto Sacchi
    Abstract Although the ability to vocalize is widespread among tortoises, the mechanisms of sound production in chelonians remain undescribed. In this study, we analyze the morphology and histology of the larynx of three species of Testudinidae (Testudo hermanni, T. graeca, and T. marginata) in order to ascertain the presence of vibrating acoustic structure, and based on our findings we propose a general model for phonation in tortoises. The structure of the larynx of the three tortoises analyzed is simple: three cartilages (the cricoid and two arytenoids) form the skeleton of the larynx, while two pairs of muscles (the dilators and constrictors) control the widening and closing of the glottis. The larynx is supported in the oral cavity by the hyoid cartilage, which in tortoises assumes the same functions of the thyroid cartilage of mammals. Two bands of elastic fibers are inserted in the lateral walls of the larynx just upstream of the glottis, and can be stretched away from the hyoid by the movements of the arytenoids. Their position and structure suggest that these bands are capable of vibrating during exhalation, and therefore may be considered vocal cords. The cricoid of T. marginata and T. graeca hold two diverticula, not previously reported, which might function as a low-frequency resonating chamber, improving the harmonic structure of tortoise calls. The structure of the larynx is compared with that of other vertebrates and the relationships between morphology and phonation are discussed. This is the first detailed description of anatomical structures possibly devoted to vocalization in chelonians. J. Morphol. 261:175,183, 2004. © 2004 Wiley-Liss, Inc. [source]

    Vertebrate limb development and possible clues to diversity in limb form

    Cheryll Tickle
    Abstract Chick embryos are good models for vertebrate development. The principles that underlie chick wing development have been discovered and there is increasing knowledge about the molecules involved. The importance of identifying molecules is that this provides a direct link to understanding the genetic basis of diversity in form. Chick wing development will be compared with limb development in other vertebrates. Possible mechanisms that could lead to variations in form, including limb reductions and limblessness, differences between fore- and hindlimbs, limb proportions, and interdigital webbing can be suggested. J. Morphol. 252:29,37, 2002. © 2002 Wiley-Liss, Inc. [source]

    The catalytic domain of human neuropathy target esterase mediates an organophosphate-sensitive ionic conductance across liposome membranes

    Philip J. Forshaw
    In humans and other vertebrates, reaction of organophosphates with a neuronal membrane protein, neuropathy target esterase (NTE), initiates events which culminate in axonal degeneration. The initiation process appears to involve modification of a property of the protein distinct from its esterase activity, subsequent to formation of a negatively charged adduct with the active site serine residue. Here, we show that membrane patches from liposomes containing NEST, a recombinant hydrophobic polypeptide comprising the esterase domain of human NTE, display a transmembrane ionic conductance with both stable and high-frequency flickering components. An asymmetric current,voltage relationship suggested that ion flow was favoured in one direction relative to the membrane and its associated NEST molecules. Flow of anions was slightly favoured compared with cations. The flickering current formed a much larger proportion of the overall conductance in patches containing wild-type NEST compared with the catalytically inactive S966A mutant form of the protein. The conductance across patches containing NEST, but not those with the S966A mutant, was significantly reduced after adding neuropathic organophosphates to the bathing medium. By contrast, non-neuropathic covalent inhibitors of the catalytic activity of NEST did not reduce NEST-mediated conductance. Future work may establish whether NTE itself mediates an organophosphate-sensitive ion flux across intracellular membranes within intact cells. [source]

    Roles of Corticotropin-Releasing Factor, Neuropeptide Y and Corticosterone in the Regulation of Food Intake In Xenopus laevis

    E. J. Crespi
    Abstract In mammals, hypothalamic control of food intake involves counterregulation of appetite by anorexigenic peptides such as corticotropin-releasing factor (CRF), and orexigenic peptides such as neuropeptide Y (NPY). Glucocorticoids also stimulate food intake by inhibiting CRF while facilitating NPY actions. To gain a better understanding of the diversity and evolution of neuroendocrine feeding controls in vertebrates, we analysed the effects of CRF, NPY and glucocorticoids on food intake in juvenile Xenopus laevis. We also analysed brain CRF and NPY mRNA content and plasma corticosterone concentrations in relation to nutritional state. Intracerebroventricular (i.c.v.) injection of ovine CRF suppressed food intake while CRF receptor antagonist ,helical CRF(9,41) significantly increased food intake relative to uninjected and placebo controls. By contrast, i.c.v. injection of frog NPY and short-term corticosterone treatment increased food intake. Semi-quantitative reverse transcription-polymerase chain reaction analyses showed that CRF and NPY mRNA fluctuated with food intake in the brain region containing the mid-posterior hypothalamus, pretectum, and optic tectum: CRF mRNA decreased 6 h after a meal and remained low through 31 days of food deprivation; NPY mRNA content also decreased 6 h after a meal, but increased to prefeeding levels by 24 h. Plasma corticosterone concentration increased 6 h after a meal, returned to prefeeding levels by 24 h, and did not change with prolonged food deprivation. This postprandial increase in plasma corticosterone may be related to the subsequent increase in plasma glucose and body water content that occurs 24 h postfeeding. Overall, our data support the conclusion that, similar to other vertebrates, CRF is anorexigenic while NPY is orexigenic in X. laevis, and CRF secretion modulates food intake in the absence of stress by exerting an inhibitory tone on appetite. Furthermore, the stress axis is activated in response to food intake, but in contrast to mammals and birds is not activated during periods of food deprivation. [source]

    Mammalian tooth marks on the bones of dinosaurs and other Late Cretaceous vertebrates

    PALAEONTOLOGY, Issue 4 2010
    Abstract:, We describe bones from the Late Cretaceous of Alberta , including bones of large dinosaurs, a femur from the aquatic reptile Champsosaurus, and a dentary from the marsupial Eodelphis, that bear tooth marks made by animals with opposing pairs of teeth. Of the animals known from the Late Cretaceous of North America, only mammals are capable of making such tooth marks. In particular, multituberculates, which have paired upper and lower incisors, are the most likely candidates for the makers of these traces. The traces described here represent the oldest known mammalian tooth marks. Although it is possible that some of these tooth marks represent feeding traces, the tooth marks often penetrate deep into the dense cortices of the bone. This raises the possibility that, much as extant mammals gnaw bone and antler, some Cretaceous mammals may have consumed the bones of dinosaurs and other vertebrates as a source of minerals. However, none of the tooth marks described here resemble the extensive gnaw traces produced by Cenozoic multituberculates or rodents. This suggests that specialized gnawing forms may have been rare or absent in the Late Cretaceous of North America. [source]

    Host intrinsic determinants and potential consequences of parasite infection in free-ranging red-fronted lemurs (Eulemur fulvus rufus)

    Dagmar Clough
    Abstract Parasites and infectious diseases represent ecological forces shaping animal social evolution. Although empirical studies supporting this link abound in various vertebrate orders, both the study of the dynamics and impact of parasite infections and infectious diseases in strepsirrhine primates have received little empirical attention. We conducted a longitudinal parasitological study on four groups of wild red-fronted lemurs (Eulemur fulvus rufus) at Kirindy Forest, Madagascar, during two field seasons in consecutive years to investigate i) the degree of gastrointestinal parasite infection on population and individual levels and ii) factors potentially determining individual infection risk. Using a comprehensive dataset with multiple individually assignable parasite samples as well as information on age, sex, group size, social rank, and endocrine status (fecal androgen and glucocorticoid), we examined parasite infection patterns and host traits that may affect individual infection risk. In addition, we examined whether parasite infection affects mating and reproductive success. Our results indicated high variability in parasite infection on individual and population levels. Time of year and group size was important determinants of variability in parasite infection. Variation in hormone levels was also associated with parasite species richness and parasite infection intensity. Differences in parasite infection between years indicate a potential immune-enhancing function of steroid hormones on nematode infections, which has not been reported before from other vertebrates studied under natural conditions. Male mating and reproductive success were not correlated to any measure of parasite infection, which suggests a nonfunctional role of the parasites we examined in primate sexual selection. Am J Phys Anthropol, 2010. © 2010 Wiley-Liss, Inc. [source]

    Modulation of Ovarian Function in Female Dogs Immunized with Bovine Luteinizing Hormone Receptor

    BB Saxena
    Adult female dogs were immunized with 0.5 mg bovine luteinizing hormone receptor (LH-R) encapsulated in a silastic subdermal implant and subsequently with four intramuscular booster injections of 0.1 mg LH-R each. Circulating LH-R antibody was detected in the sera 3 weeks post-implant. The appearance of LH-R antibody was associated with a decline in the serum progesterone concentrations to a range of 0,0.5 ng/ml until day 365 in the immunized dogs in comparison with a range of 5,10 ng in the control animals, suggesting a lack of ovulation and corpus luteum function in immunized dogs. The immunized dogs did not show signs of `standing heat' and failed to ovulate when induced by LH-RH challenge. Serum oestradiol levels, however, remained in the range of 30,40 pg/ml in both the immunized and the control dogs. With the decline in the antibody titres, the hormonal profile and vaginal cytology returned to a fertile state and the dogs exhibited signs of `standing heat', as well as vaginal bleeding. Dogs immunized with LH-R did not show any serious metabolic, local or systemic adverse effects. The hypothalamic,pituitary gonadal axis remained intact as indicated by little difference in pituitary LH levels between control and immunized animals, and by the release of LH by LH-RH challenge. These studies demonstrate that active immunization of female dogs with LH-R could immunomodulate ovarian function to cause a reversible state of infertility. It may be postulated that, due to extensive interspecies homology, a recombinant LH receptor-based immunocontraceptive vaccine may also be effective in other vertebrates. [source]

    Calcium-binding protein immunoreactivity characterizes the auditory system of Gekko gecko

    Kai Yan
    Abstract Geckos use vocalizations for intraspecific communication, but little is known about the organization of their central auditory system. We therefore used antibodies against the calcium-binding proteins calretinin (CR), parvalbumin (PV), and calbindin-D28k (CB) to characterize the gecko auditory system. We also examined expression of both glutamic acid decarboxlase (GAD) and synaptic vesicle protein (SV2). Western blots showed that these antibodies are specific to gecko brain. All three calcium-binding proteins were expressed in the auditory nerve, and CR immunoreactivity labeled the first-order nuclei and delineated the terminal fields associated with the ascending projections from the first-order auditory nuclei. PV expression characterized the superior olivary nuclei, whereas GAD immunoreactivity characterized many neurons in the nucleus of the lateral lemniscus and some neurons in the torus semicircularis. In the auditory midbrain, the distribution of CR, PV, and CB characterized divisions within the central nucleus of the torus semicircularis. All three calcium-binding proteins were expressed in nucleus medialis of the thalamus. These expression patterns are similar to those described for other vertebrates. J. Comp. Neurol. 518:3409,3426, 2010. © 2010 Wiley-Liss, Inc. [source]

    Distribution of sex steroid hormone receptors in the brain of an African cichlid fish, Astatotilapia burtoni

    Lauren A. Munchrath
    Abstract Sex steroid hormones released from the gonads play an important role in mediating social behavior across all vertebrates. Many effects of these gonadal hormones are mediated by nuclear steroid hormone receptors, which are crucial for integration in the brain of external (e.g., social) signals with internal physiological cues to produce an appropriate behavioral output. The African cichlid fish Astatotilapia burtoni presents an attractive model system for the study of how internal cues and external social signals are integrated in the brain as males display robust plasticity in the form of two distinct, yet reversible, behavioral and physiological phenotypes depending on the social environment. In order to better understand where sex steroid hormones act to regulate social behavior in this species, we have determined the distribution of the androgen receptor, estrogen receptor alpha, estrogen receptor beta, and progesterone receptor mRNA and protein throughout the telencephalon and diencephalon and some mesencephalic structures of A. burtoni. All steroid hormone receptors were found in key brain regions known to modulate social behavior in other vertebrates including the proposed teleost homologs of the mammalian amygdalar complex, hippocampus, striatum, preoptic area, anterior hypothalamus, ventromedial hypothalamus, and ventral tegmental area. Overall, there is high concordance of mRNA and protein labeling. Our results significantly extend our understanding of sex steroid pathways in the cichlid brain and support the important role of nuclear sex steroid hormone receptors in modulating social behaviors in teleosts and across vertebrates. J. Comp. Neurol. 518:3302,3326, 2010. © 2010 Wiley-Liss, Inc. [source]

    Genoarchitectonic profile of developing nuclear groups in the chicken pretectum

    J.L. Ferran
    Abstract Earlier results on molecularly coded progenitor domains in the chicken pretectum revealed an anteroposterior subdivision of the pretectum in precommissural (PcP), juxtacommissural (JcP), and commissural (CoP) histogenetic areas, each specified differentially (Ferran et al. [2007] J Comp Neurol 505:379,403). Here we examined the nuclei derived from these areas with regard to characteristic gene expression patterns and gradual histogenesis (eventually, migration patterns). We sought a genoarchitectonic schema of the avian pretectum within the prosomeric model of the vertebrate forebrain (Puelles and Rubenstein [2003] Trends Neurosci 26:469,476; Puelles et al. [2007] San Diego: Academic Press). Transcription-factor gene markers were used to selectively map derivatives of the three pretectal histogenetic domains: Pax7 and Pax6 (CoP); FoxP1 and Six3 (JcP); and FoxP2, Ebf1, and Bhlhb4 (PcP). The combination of this genoarchitectonic information with additional data on Lim1, Tal2, and Nbea mRNA expression and other chemoarchitectonic results allowed unambiguous characterization of some 30 pretectal nuclei. Apart from grouping them as derivatives of the three early anteroposterior domains, we also assigned them to postulated dorsoventral subdomains (Ferran et al. [2007]). Several previously unknown neuronal populations were detected, thus expanding the list of pretectal structures, and we corrected some apparently confused concepts in the earlier literature. The composite gene expression map represents a substantial advance in anatomical and embryological knowledge of the avian pretectum. Many nuclear primordia can be recognized long before the mature differentiated state of the pretectum is achieved. This study provides fundamental notions for ultimate scientific study of the specification and regionalization processes building up this brain area, both in birds and other vertebrates. J. Comp. Neurol. 517:405,451, 2009. © 2009 Wiley-Liss, Inc. [source]

    Visual subdivisions of the dorsal ventricular ridge of the iguana (Iguana iguana) as determined by electrophysiologic mapping

    Paul R. Manger
    Abstract The dorsal ventricular ridge (DVR) of reptiles is one of two regions of the reptilian telencephalon that receives input from the dorsal thalamus. Although studies demonstrate that two visual thalamic nuclei, the dorsal lateral geniculate and rotundus, send afferents to the dorsal cortex and DVR, respectively, relatively little is known about physiologic representations. The present study determined the organization of the visual recipient region of the iguana DVR. Microelectrode mapping techniques were used to determine the extent, number of subdivisions, and retinotopy within the visually responsive region of the anterior DVR (ADVR). Visually responsive neurons were restricted to the anterior two thirds of the ADVR. Within this region, two topographically organized subdivisions were determined. Each subdivision contained a full representation of the visual field and could be distinguished from the other by differences in receptive field properties and reversals in receptive field progressions across their mutual border. A third subdivision of the ADVR, in which neurons are responsive to visual stimulation is also described; however, a distinct visuotopic representation could not be determined for this region. This third region forms a shell surrounding the lateral, dorsal, and medial aspects of the topographically organized subdivisions. These results demonstrate that there are multiple physiologic subdivisions in the thalamic recipient zone of the ADVR of the iguana. Comparisons to the ADVR of other reptiles are made, homologies to ectostriatial regions of the bird are proposed, and the findings are discussed in relation to telencephalic organization of other vertebrates. J. Comp. Neurol. 453:226,246, 2002. © 2002 Wiley-Liss, Inc. [source]

    A New Look on the Origin of the Gonad and the Müllerian Duct: the Sturgeon (Acipencer) as a Model for Vertebrate Urogenital Development

    K. -H.
    The origin of the vertebrate gonad and the Müllerian duct are still a matter of debate. According to the majority of recent textbooks, the gonad is a product of the proliferating coelothelium and therefore derived from the mesoderm of the lateral plate region. The Müllerian duct grows parallel to the Wolffian duct, but it is not clear to what extent the latter contributes actively to the development of the former. In the last decade, we reinvestigated early gonadogenesis and Müllerian duct development in a number of vertebrate model species using various morphological techniques (TEM, SEM, immunohistochemistry). The conclusion of our studies is that rudimentary or regressing nephrostomial tubules, particularly cells of their nephrostomes, must be regarded as the immediate precursors of the somatic cells of the gonadal crest and the Müllerian infundibular field. According to this concept, both structures are derivatives of the intermediate mesoderm. Nephrostomial tubules are regular components of the primitive pro- and mesonephros. They connect the nephric tubule or the nephric corpuscle to the coelomic cavity and open into the latter by means of a funnel-like mouth, the nephrostome (coelomostome). In the larval sterlet, Acipenser ruthenus, short, segmentally arranged nephrostomial tubules with well-developed nephrostomes are present in the region of the cranial opisthonephros. Cells of the medial nephrostomial lips proliferate, surround the germ cells that have accumulated in this location and form a continuous gonadal crest. Cells of the lateral nephrostomial lips proliferate also, spread out on the coelomic surface, replace the original flat mesothelial cells over the Wolffian duct and the cranial opisthonephros and form the Müllerian infundibular field. At about 28 days, a flat pocket begins to invaginate the infundibular field. This pocket is the primordium of the Müllerian ostium abdominale. The findings in Acipenser can be generalized and transferred to other vertebrates. [source]

    Stereology of the Liver in Three Species of Leontopithecus (Lesson, 1840) Callitrichidae , Primates

    C. H. F. Burity
    Summary Studies on liver morphology and stereology are relevant to the comparative anatomical and pathological research. They also facilitate the use of non-human primates in basic research, which has substantially supported studies in human medicine. Quantitative studies of liver structures have also been more extensive in Old World primates and other vertebrates. Twenty-three livers of adult lion tamarins were studied (six Leontopithecus rosalia, seven Leontopithecus chrysomelas, and 10 Leontopithecus chrysopygus), dissected, and fixed in 10% neutral buffered formalin solution. For stereological quantification, the liver was regarded as consisting of parenchyma (hepatocytes) and stroma (non-hepatocytes). The volume density (Vv) was determined by point counting, and the disector method was used to obtain the numerical density of hepatocytes (Nv). Hepatic stereological differences among the three species of lion tamarins were not statistically significant. Therefore, the pooled Vv[hepatocyte] and Vv[stroma] could be determined as 96.2 and 7.4%, respectively, and Nv[hepatocyte] as 500.33 × 106 cm,3 . Significantly different, the values found for Vv[hepatocyte] and Nv[hepatocyte] in lion tamarins were, respectively, 0.09 and 2.8 times greater than those in baboons, and 0.17 and 3.8 times greater than those in man. However, the Vv[stroma] was 1.04 times smaller than that in baboons and 1.79 times smaller than that in man. [source]