| isolation and structural characterization of insulin and glucagon from the holocephalan species callorhynchus milii (elephantfish). | both insulin and glucagon from the pancreas of the holocephalan cartilaginous fish callorhynchus milii (elephantfish) have been isolated and purified. two reverse-phase h.p.l.c. steps enabled recovery of sufficient material for gas-phase sequencing of the intact chains as well as peptide digestion products. the elephantfish insulin sequence shows 14 differences from pig insulin, including two unusual substitutions, val-a14 and gln-b30, though none of these is thought likely to influence receptor ... | 1989 | 2690815 |
| presence of intestinal, liver and heart/adipocyte fatty-acid-binding protein types in the liver of a chimaera fish. | five fatty-acid-binding proteins from the liver of the elephant fish (callorhynchus callorhynchus), a chimaera fish that belongs--together with the elasmobranchs--to the ancient chondrichthyes class were isolated and characterized. the purification procedures for these proteins involved gel filtration, anion-exchange chromatography, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis as a last step. they were submitted to "in gel" tryptic or cyanogen bromide digestion and the resulting ... | 1998 | 9924809 |
| the main fatty acid-binding protein in the liver of the shark (halaetunus bivius) belongs to the liver basic type. isolation, amino acid sequence determination and characterization. | three fatty acid-binding proteins (fabps) from the liver of the shark halaetunus bivius were isolated and characterized: one of them belongs to the liver-type fabp family and the other two to the heart-type fabp family. the complete primary structure of the first fabp, and partial primary structures of the two others, were determined. the liver-type fabp constitutes 69% of the total fabps, and its amino acid sequence presents the highest identity with chicken, catfish, iguana and elephant fish l ... | 1999 | 10504416 |
| ancient noncoding elements conserved in the human genome. | cartilaginous fishes represent the living group of jawed vertebrates that diverged from the common ancestor of human and teleost fish lineages about 530 million years ago. we generated approximately 1.4x genome sequence coverage for a cartilaginous fish, the elephant shark (callorhinchus milii), and compared this genome with the human genome to identify conserved noncoding elements (cnes). the elephant shark sequence revealed twice as many cnes as were identified by whole-genome comparisons betw ... | 2006 | 17185593 |
| mechanisms of vasodilation in the dorsal aorta of the elephant fish, callorhinchus milii (chimaeriformes: holocephali). | this study investigated vasodilator mechanisms in the dorsal aorta of the elephant fish, callorhinchus milii, using anatomical and physiological approaches. nitric oxide synthase could only be located in the perivascular nerve fibres and not the endothelium of the dorsal aorta, using nadph histochemistry and immunohistochemistry. in vitro organ bath experiments demonstrated that a no/soluble guanylyl cyclase (gc) system appeared to be absent in the vascular smooth muscle, since the no donors snp ... | 2007 | 17342492 |
| survey sequencing and comparative analysis of the elephant shark (callorhinchus milii) genome. | owing to their phylogenetic position, cartilaginous fishes (sharks, rays, skates, and chimaeras) provide a critical reference for our understanding of vertebrate genome evolution. the relatively small genome of the elephant shark, callorhinchus milii, a chimaera, makes it an attractive model cartilaginous fish genome for whole-genome sequencing and comparative analysis. here, the authors describe survey sequencing (1.4x coverage) and comparative analysis of the elephant shark genome, one of the ... | 2007 | 17407382 |
| elephant shark sequence reveals unique insights into the evolutionary history of vertebrate genes: a comparative analysis of the protocadherin cluster. | cartilaginous fishes are the oldest living phylogenetic group of jawed vertebrates. here, we demonstrate the value of cartilaginous fish sequences in reconstructing the evolutionary history of vertebrate genomes by sequencing the protocadherin cluster in the relatively small genome (910 mb) of the elephant shark (callorhinchus milii). human and coelacanth contain a single protocadherin cluster with 53 and 49 genes, respectively, that are organized in three subclusters, pcdhalpha, pcdhbeta, and p ... | 2008 | 18319338 |
| identification of angiotensinogen genes with unique and variable angiotensin sequences in chondrichthyans. | the renin-angiotensin system is an enzyme-linked hormonal cascade that plays an important role in body fluid and cardiovascular regulation. the system is initiated by the action of renin on the precursor protein, angiotensinogen (agt), whose sequence information is scarce because of its high variability among species. in the present study, we cloned agt in chondrichthyans (elasmobranchs: triakis scyllium, dasyatis akajei,leucoraja erinacea and a holocephalan: callorhinchus milii). homology was l ... | 2009 | 19071126 |
| characterization of the neurohypophysial hormone gene loci in elephant shark and the japanese lamprey: origin of the vertebrate neurohypophysial hormone genes. | vasopressin and oxytocin are mammalian neurohypophysial hormones with distinct functions. vasopressin is involved mainly in osmoregulation and oxytocin is involved primarily in parturition and lactation. jawed vertebrates contain at least one homolog each of vasopressin and oxytocin, whereas only a vasopressin-family hormone, vasotocin, has been identified in jawless vertebrates. the genes encoding vasopressin and oxytocin are closely linked tail-to-tail in eutherian mammals whereas their homolo ... | 2009 | 19243634 |
| [description of three new monogenean gill parasites from mormyrus rume (valenciennes, 1846) (teleostei: mormyridae) in ivory coast]. | the study of the gill parasites from elephant fish mormyrus rume valenciennes, 1846 (teleostei: mormyridae) from the ayamé man-made lake (ivory coast) revealed the presence of three new monogenean species of the genus bouixella euzet & dossou, 1976, which can be mainly distinguished from all other species of the genus by the morphology and the size of the sclerotised parts of the haptor (dorsal and ventral anchor, dorsal and ventral bar) and by the size and the structure of the male copulatory o ... | 2009 | 19353952 |
| comparative genomics of chondrichthyan hoxa clusters. | the chondrichthyan or cartilaginous fish (chimeras, sharks, skates and rays) occupy an important phylogenetic position as the sister group to all other jawed vertebrates and as an early lineage to diverge from the vertebrate lineage following two whole genome duplication events in vertebrate evolution. there have been few comparative genomic analyses incorporating data from chondrichthyan fish and none comparing genomic information from within the group. we have sequenced the complete hoxa clust ... | 2009 | 19725973 |
| elephant shark (callorhinchus milii) provides insights into the evolution of hox gene clusters in gnathostomes. | we have sequenced and analyzed hox gene clusters from elephant shark, a holocephalian cartilaginous fish. elephant shark possesses 4 hox clusters with 45 hox genes that include orthologs for a higher number of ancient gnathostome hox genes than the 4 clusters in tetrapods and the supernumerary clusters in teleost fishes. phylogenetic analysis of elephant shark hox genes from 7 paralogous groups that contain all of the 4 members indicated an ((ab)(cd)) topology for the order of hox cluster duplic ... | 2009 | 19805301 |
| functional conservation of a forebrain enhancer from the elephant shark (callorhinchus milii ) in zebrafish and mice. | the phylogenetic position of the elephant shark (callorhinchus milii ) is particularly relevant to study the evolution of genes and gene regulation in vertebrates. here we examine the evolution of dlx homeobox gene regulation during vertebrate embryonic development with a particular focus on the forebrain. we first identified the elephant shark sequence orthologous to the ure2 cis -regulatory element of the mouse dlx1/dlx2 locus (herein named cmure2). we then conducted a comparative study of the ... | 2010 | 20504318 |
| evolutionary origin and phylogeny of the modern holocephalans (chondrichthyes: chimaeriformes): a mitogenomic perspective. | with our increasing ability for generating whole-genome sequences, comparative analysis of whole genomes has become a powerful tool for understanding the structure, function, and evolutionary history of human and other vertebrate genomes. by virtue of their position basal to bony vertebrates, cartilaginous fishes (class chondrichthyes) are a valuable outgroup in comparative studies of vertebrates. recently, a holocephalan cartilaginous fish, the elephant shark, callorhinchus milii (subclass holo ... | 2010 | 20551041 |
| comparative genomics approach to detecting split-coding regions in a low-coverage genome: lessons from the chimaera callorhinchus milii (holocephali, chondrichthyes). | recent development of deep sequencing technologies has facilitated de novo genome sequencing projects, now conducted even by individual laboratories. however, this will yield more and more genome sequences that are not well assembled, and will hinder thorough annotation when no closely related reference genome is available. one of the challenging issues is the identification of protein-coding sequences split into multiple unassembled genomic segments, which can confound orthology assignment and ... | 2011 | 21712341 |
| body fluid osmolytes and urea and ammonia flux in the colon of two chondrichthyan fishes, the ratfish, hydrolagus colliei, and spiny dogfish, squalus acanthias. | the present study has examined the role of the colon in regulating ammonia and urea nitrogen balance in two species of chondrichthyans, the ratfish, hydrolagus colliei (a holocephalan) and the spiny dogfish, squalus acanthias (an elasmobranch). stripped colonic tissue from both the dogfish and ratfish was mounted in an ussing chamber and in both species bi-directional urea flux was found to be negligible. urea uptake by the mucosa and serosa of the isolated colonic epithelium through accumulatio ... | 2012 | 21911071 |
| the evolution of the scavenger receptor cysteine-rich domain of the class a scavenger receptors. | the class a scavenger receptor (ca-sr) family is a group of five evolutionarily related innate immune receptors. the ca-srs are known for their promiscuous ligand binding; as they have been shown to bind bacteria, such as streptococcus pneumoniae and escherichia coli, as well as different modified forms of low-density lipoprotein. three of the five family members possess a scavenger receptor cysteine-rich (srcr) domain while the remaining two receptors lack the domain. previous work has suggeste ... | 2015 | 26217337 |
| scaffolding low quality genomes using orthologous protein sequences. | the ready availability of next-generation sequencing has led to a situation where it is easy to produce very fragmentary genome assemblies. we present a pipeline, swips (scaffolding with protein sequences), that uses orthologous proteins to improve low quality genome assemblies. the protein sequences are used as guides to scaffold existing contigs, while simultaneously allowing the gene structure to be predicted by homology. | 2012 | 23162087 |
| the evolution of tenascins and fibronectin. | tenascins are extracellular matrix glycoproteins that act both as integrin ligands and as modifiers of fibronectin-integrin interactions to regulate cell adhesion, migration, proliferation and differentiation. in tetrapods, both tenascins and fibronectin bind to integrins via rgd and ldv-type tripeptide motifs found in exposed loops in their fibronectin-type iii domains. we previously showed that tenascins appeared early in the chordate lineage and are represented by single genes in extant cepha ... | 2015 | 25482621 |
| into the blue: gene duplication and loss underlie color vision adaptations in a deep-sea chimaera, the elephant shark callorhinchus milii. | the cartilaginous fishes reside at the base of the gnathostome lineage as the oldest extant group of jawed vertebrates. recently, the genome of the elephant shark, callorhinchus milii, a chimaerid holocephalan, has been sequenced and therefore becomes the first cartilaginous fish to be analyzed in this way. the chimaeras have been largely neglected and very little is known about the visual systems of these fishes. by searching the elephant shark genome, we have identified gene fragments encoding ... | 2009 | 19196633 |
| livebearing or egg-laying mammals: 27 decisive nucleotides of fam168. | in the present study, we determine comprehensive molecular phylogenetic relationships of the novel myelin-associated neurite-outgrowth inhibitor (mani) gene across the entire eukaryotic lineage. combined computational genomic and proteomic sequence analyses revealed mani as one of the two members of the novel family with sequence similarity 168 member (fam168) genes, consisting of fam168a and fam168b, having distinct genetic differences that illustrate diversification in its biological function ... | 2017 | 28381702 |
| <i>hydrolagus</i> <i>erithacus</i> sp. nov. (chimaeriformes: chimaeridae), a new species of chimaerid from the southeastern atlantic and southwestern indian oceans. | a new species of chimaerid, hydrolagus erithacus sp. nov., is described from nine specimens collected from the southeast atlantic and southwest indian oceans from depths of 470-1,000 meters. this species is distinguished from all other hydrolagus species based on the following characteristics: head bulky, relatively large, followed by stocky body; head and body height from about pectoral fin origin to pelvic fin origin similar, then tapering rapidly to filamentous tail; first dorsal fin spine he ... | 2017 | 28187604 |
| evolution of specificity in cartilaginous fish glycoprotein hormones and receptors. | glycoprotein hormones (gph) interact very specifically with their receptors to mediate hypothalamic-pituitary-peripheral gland endocrine signaling. vertebrates typically have three functionally distinct gph endocrine signaling complexes: follicle-stimulating hormone, luteinizing hormone, and thyroid-stimulating hormone, and their receptors. each hormone consists of a common α subunit bound to one of three different β subunits. individual hormone subunits and receptors are present in genomes of e ... | 2017 | 28062301 |
| data for amino acid alignment of japanese stingray melanocortin receptors with other gnathostome melanocortin receptor sequences, and the ligand selectivity of japanese stingray melanocortin receptors. | this article contains structure and pharmacological characteristics of melanocortin receptors (mcrs) related to research published in "characterization of melanocortin receptors from stingray dasyatis akajei, a cartilaginous fish" (takahashi et al., 2016) [1]. the amino acid sequences of the stingray, d. akajei, mc1r, mc2r, mc3r, mc4r, and mc5r were aligned with the corresponding melanocortin receptor sequences from the elephant shark, callorhinchus milii, the dogfish, squalus acanthias, the gol ... | 2016 | 27408924 |
| corticotropin-releasing hormone family evolution: five ancestral genes remain in some lineages. | the evolution of the peptide family consisting of corticotropin-releasing hormone (crh) and the three urocortins (ucn1-3) has been puzzling due to uneven evolutionary rates. distinct gene duplication scenarios have been proposed in relation to the two basal rounds of vertebrate genome doubling (2r) and the teleost fish-specific genome doubling (3r). by analyses of sequences and chromosomal regions, including many neighboring gene families, we show here that the vertebrate progenitor had two pept ... | 2016 | 27220618 |
| on the vagal cardiac nerves, with special reference to the early evolution of the head-trunk interface. | the vagus nerve, or the tenth cranial nerve, innervates the heart in addition to other visceral organs, including the posterior visceral arches. in amniotes, the anterior and posterior cardiac branches arise from the branchial and intestinal portions of the vagus nerve to innervate the arterial and venous poles of the heart, respectively. the evolution of this innervation pattern has yet to be elucidated, due mainly to the lack of morphological data on the vagus in basal vertebrates. to investig ... | 2016 | 27216138 |
| sulfate transporters involved in sulfate secretion in the kidney are localized in the renal proximal tubule ii of the elephant fish (callorhinchus milii). | most vertebrates, including cartilaginous fishes, maintain their plasma so4 (2-) concentration ([so4 (2-)]) within a narrow range of 0.2-1 mm. as seawater has a [so4 (2-)] about 40 times higher than that of the plasma, so4 (2-) excretion is the major role of kidneys in marine teleost fishes. it has been suggested that cartilaginous fishes also excrete excess so4 (2-) via the kidney. however, little is known about the underlying mechanisms for so4 (2-) transport in cartilaginous fish, largely due ... | 2016 | 27122370 |
| calcium activated k⁺ channels in the electroreceptor of the skate confirmed by cloning. details of subunits and splicing. | elasmobranchs detect small potentials using excitable cells of the ampulla of lorenzini which have calcium-activated k(+) channels, first described in 1974. a distinctive feature of the outward current in voltage clamped ampullae is its apparent insensitivity to voltage. the sequence of a bk channel α isoform expressed in the ampulla of the skate was characterized. a signal peptide is present at the beginning of the gene. when compared to human isoform 1 (the canonical sequence), the largest dif ... | 2016 | 26687710 |
| delay-dependent response in weakly electric fish under closed-loop pulse stimulation. | in this paper, we apply a real time activity-dependent protocol to study how freely swimming weakly electric fish produce and process the timing of their own electric signals. specifically, we address this study in the elephant fish, gnathonemus petersii, an animal that uses weak discharges to locate obstacles or food while navigating, as well as for electro-communication with conspecifics. to investigate how the inter pulse intervals vary in response to external stimuli, we compare the response ... | 2015 | 26473597 |
| development of the synarcual in the elephant sharks (holocephali; chondrichthyes): implications for vertebral formation and fusion. | the synarcual is a structure incorporating multiple elements of two or more anterior vertebrae of the axial skeleton, forming immediately posterior to the cranium. it has been convergently acquired in the fossil group 'placodermi', in chondrichthyes (holocephali, batoidea), within the teleost group syngnathiformes, and to varying degrees in a range of mammalian taxa. in addition, cervical vertebral fusion presents as an abnormal pathology in a variety of human disorders. vertebrae develop from a ... | 2015 | 26339918 |
| discovery of conventional prolactin from the holocephalan elephant fish, callorhinchus milii. | the conventional prolactin (prl), also known as prl1, is an adenohypophysial hormone that critically regulates various physiological events in reproduction, metabolism, growth, osmoregulation, among others. prl1 shares its evolutionary origin with prl2, growth hormone (gh), somatolactin and placental lactogen, which together form the gh/prl hormone family. previously, several bioassays implied the existence of prl1 in elasmobranch pituitaries. however, to date, all attempts to isolate prl1 from ... | 2015 | 26320855 |
| origin and diversification of meprin proteases. | meprins are astacin metalloproteases with a characteristic, easily recognizable structure, given that they are the only proteases with both mam and math domains plus a transmembrane region. so far assumed to be vertebrate-specific, it is shown here, using a combination of evolutionary and genomic analyses, that meprins originated before the urochordates/vertebrates split. in particular, three genes encoding structurally typical meprin proteins are arranged in tandem in the genome of the urochord ... | 2015 | 26288188 |
| morphological and molecular investigations of the holocephalan elephant fish nephron: the existence of a countercurrent-like configuration and two separate diluting segments in the distal tubule. | in marine cartilaginous fish, reabsorption of filtered urea by the kidney is essential for retaining a large amount of urea in their body. however, the mechanism for urea reabsorption is poorly understood due to the complexity of the kidney. to address this problem, we focused on elephant fish (callorhinchus milii) for which a genome database is available, and conducted molecular mapping of membrane transporters along the different segments of the nephron. basically, the nephron architecture of ... | 2015 | 26183720 |
| the surface topography of callorhynchocotyle callorhynchi (manter, 1955) (monogenea: hexabothriidae), a parasite of the holocephalan fish callorhinchus capensis. | a scanning electron microscopical study, incorporating some transmission electron microscopical observations, was undertaken on the surface topography of the gill parasite callorhynchocotyle callorhynchi (manter, 1955) (monogenea: hexabothriidae) from the cape elephant fish callorhinchus capensis (holocephali) off the western coast of south africa. the study revealed the presence of several new characteristics for this species. these include the presence of regularly distributed, knob-shaped pro ... | 2015 | 26063532 |
| extensive retroviral diversity in shark. | retroviruses infect a wide range of vertebrates. however, little is known about the diversity of retroviruses in basal vertebrates. endogenous retrovirus (erv) provides a valuable resource to study the ecology and evolution of retrovirus. | 2015 | 25927737 |
| ancient duplications and expression divergence in the globin gene superfamily of vertebrates: insights from the elephant shark genome and transcriptome. | comparative analyses of vertebrate genomes continue to uncover a surprising diversity of genes in the globin gene superfamily, some of which have very restricted phyletic distributions despite their antiquity. genomic analysis of the globin gene repertoire of cartilaginous fish (chondrichthyes) should be especially informative about the duplicative origins and ancestral functions of vertebrate globins, as divergence between chondrichthyes and bony vertebrates represents the most basal split with ... | 2015 | 25743544 |
| molecular characterization of betaine-homocysteine methyltransferase 1 from the liver, and effects of aestivation on its expressions and homocysteine concentrations in the liver, kidney and muscle, of the african lungfish, protopterus annectens. | homocysteine accumulation has numerous deleterious effects, and betaine-homocysteine s-methyltransferase (bhmt) catalyses the synthesis of methionine from homocysteine and betaine. this study aimed to determine homocysteine concentrations, and mrna expression levels and protein abundances of bhmt1/bhmt1 in the liver, kidney and muscle of the african lungfish, protopterus annectens, during the induction (6 days), maintenance (6 months) or arousal (3 days after arousal) phase of aestivation. the h ... | 2015 | 25575738 |
| capture, transport, and husbandry of elephant sharks (callorhinchus milii) adults, eggs, and hatchlings for research and display. | elephant sharks (callorhinchus milii) have the slowest evolving genome of all vertebrates and are an interesting model species for evolution research and a prized display animal. however, their deep water habitat, short breeding season, fragility, and susceptibility to stress-induced mortality have made them difficult animals to capture, keep in captivity, and obtain fertilized eggs from. gravid females were captured by rod and reel from western port bay, australia and transferred to a 40 000 l ... | 2015 | 25400285 |
| embryonic development of fin spines in callorhinchus milii (holocephali); implications for chondrichthyan fin spine evolution. | fin spines are commonly known from fossil gnathostomes (jawed vertebrates) and are usually associated with paired and unpaired fins. they are less common among extant gnathostomes, being restricted to the median fins of certain chondrichthyans (cartilaginous fish), including chimaerids (elephant sharks) and neoselachians (sharks, skates, and rays). fin spine growth is of great interest and relevance but few studies have considered their evolution and development. we investigated the development ... | 2014 | 25378057 |
| molecular characterization of argininosuccinate synthase and argininosuccinate lyase from the liver of the african lungfish protopterus annectens, and their mrna expression levels in the liver, kidney, brain and skeletal muscle during aestivation. | argininosuccinate synthase (ass) and argininosuccinate lyase (asl) are involved in arginine synthesis for various purposes. the complete cdna coding sequences of ass and asl from the liver of protopterus annectens consisted of 1,296 and 1,398 bp, respectively. phylogenetic analyses revealed that the deduced ass and asl of p. annectens had close relationship with that of the cartilaginous fish callorhinchus milii. besides being strongly expressed in the liver, ass and asl expression were detectab ... | 2014 | 25034132 |
| runx family genes in a cartilaginous fish, the elephant shark (callorhinchus milii). | the runx family genes encode transcription factors that play key roles in hematopoiesis, skeletogenesis and neurogenesis and are often implicated in diseases. we describe here the cloning and characterization of runx1, runx2, runx3 and runxb genes in the elephant shark (callorhinchus milii), a member of chondrichthyes, the oldest living group of jawed vertebrates. through the use of alternative promoters and/or alternative splicing, each of the elephant shark runx genes expresses multiple isofor ... | 2014 | 24699678 |
| a survey of ancient conserved non-coding elements in the pax6 locus reveals a landscape of interdigitated cis-regulatory archipelagos. | biological differences between cell types and developmental processes are characterised by differences in gene expression profiles. gene-distal enhancers are key components of the regulatory networks that specify the tissue-specific expression patterns driving embryonic development and cell fate decisions, and variations in their sequences are a major contributor to genetic disease and disease susceptibility. despite advances in the methods for discovery of putative cis-regulatory sequences, cha ... | 2014 | 24440152 |
| elephant shark genome provides unique insights into gnathostome evolution. | the emergence of jawed vertebrates (gnathostomes) from jawless vertebrates was accompanied by major morphological and physiological innovations, such as hinged jaws, paired fins and immunoglobulin-based adaptive immunity. gnathostomes subsequently diverged into two groups, the cartilaginous fishes and the bony vertebrates. here we report the whole-genome analysis of a cartilaginous fish, the elephant shark (callorhinchus milii). we find that the c. milii genome is the slowest evolving of all kno ... | 2014 | 24402279 |
| urea-based osmoregulation in the developing embryo of oviparous cartilaginous fish (callorhinchus milii): contribution of the extraembryonic yolk sac during the early developmental period. | marine cartilaginous fish retain a high concentration of urea to maintain the plasma slightly hyperosmotic to the surrounding seawater. in adult fish, urea is produced by hepatic and extrahepatic ornithine urea cycles (oucs). however, little is known about the urea retention mechanism in developing cartilaginous fish embryos. in order to address the question as to the mechanism of urea-based osmoregulation in developing embryos, the present study examined the gene expression profiles of ouc enzy ... | 2014 | 24363418 |
| sex-related genomic sequences in cartilaginous fish: an overview. | sex determination and differentiation are key events in the development of either the testis or ovary in fish. sex determination mechanisms include environmental and genetic regulation. research on sex determination systems and their related genes have been implemented in the teleost species, but the amount of information about these genes in cartilaginous fish is very scarce. this paper summarizes the few available data on molecular studies and chromosome localization of specific sequences usef ... | 2013 | 24052041 |
| expression of wnt signaling skeletal development genes in the cartilaginous fish, elephant shark (callorhinchus milii). | jawed vertebrates (gnasthostomes) are broadly separated into cartilaginous fishes (chondricthyes) and bony vertebrates (osteichthyes). cartilaginous fishes are divided into chimaeras (e.g. ratfish, rabbit fish and elephant shark) and elasmobranchs (e.g. sharks, rays and skates). both cartilaginous fish and bony vertebrates are believed to have a common armoured bony ancestor (class placodermi), however cartilaginous fish are believed to have lost bone. this study has identified and investigated ... | 2013 | 23871650 |
| holocephalan embryo provides new information on the evolution of the glossopharyngeal nerve, metotic fissure and parachordal plate in gnathostomes. | the phylogenetic relationships between the different groups of paleozoic gnathostomes are still debated, mainly because of incomplete datasets on paleozoic jawed vertebrate fossils and ontogeny of some modern taxa. this issue is illustrated by the condition of the glossopharyngeal nerve relative to the parachordal plate, the otic capsules and the metotic fissure in gnathostomes. two main conditions are observed in elasmobranchs (shark and rays) and osteichthyans (bony fishes and tetrapods). the ... | 2013 | 23799138 |
| the identification of micrornas in the whitespotted bamboo shark (chiloscyllium plagiosum) liver by illumina sequencing. | micrornas are indispensable players in the regulation of a broad range of biological processes. here, we report the first deep sequencing of the whitespotted bamboo shark (chiloscyllium plagiosum) liver. we mapped 91 mirnas in the callorhinchus milii genome that have previously been described in the danio rerio, fugu rubripes, oryzias latipes, xenopus laevis, xenopus tropicalis, homo sapiens, and mus musculus. in addition, 156 new putative candidate (pc) c. plagiosum mirnas were identified. from ... | 2013 | 23791654 |
| the discovery of foxl2 paralogs in chondrichthyan, coelacanth and tetrapod genomes reveals an ancient duplication in vertebrates. | the foxl2 (forkhead box l2) gene is an important member of the forkhead domain family, primarily responsible for the development of ovaries during female sex differentiation. the evolutionary studies conducted previously considered the presence of paralog foxl2 copies only in teleosts. however, to search for possible paralog copies in other groups of vertebrates and ensure that all predicted copies were homolog to the foxl2 gene, a broad evolutionary analysis was performed, based on the forkhead ... | 2013 | 23549337 |
| sequencing of pax6 loci from the elephant shark reveals a family of pax6 genes in vertebrate genomes, forged by ancient duplications and divergences. | pax6 is a developmental control gene essential for eye development throughout the animal kingdom. in addition, pax6 plays key roles in other parts of the cns, olfactory system, and pancreas. in mammals a single pax6 gene encoding multiple isoforms delivers these pleiotropic functions. here we provide evidence that the genomes of many other vertebrate species contain multiple pax6 loci. we sequenced pax6-containing bacs from the cartilaginous elephant shark (callorhinchus milii) and found two dis ... | 2013 | 23359656 |
| evolution and functional characterisation of melanopsins in a deep-sea chimaera (elephant shark, callorhinchus milii). | non-visual photoreception in mammals is primarily mediated by two splice variants that derive from a single melanopsin (opn4m) gene, whose expression is restricted to a subset of retinal ganglion cells. physiologically, this sensory system regulates the photoentrainment of many biological rhythms, such as sleep via the melatonin endocrine system and pupil constriction. by contrast, melanopsin exists as two distinct lineages in non-mammals, opn4m and opn4x, and is broadly expressed in a wide rang ... | 2012 | 23251480 |
| sequencing and analysis of full-length cdnas, 5'-ests and 3'-ests from a cartilaginous fish, the elephant shark (callorhinchus milii). | cartilaginous fishes are the most ancient group of living jawed vertebrates (gnathostomes) and are, therefore, an important reference group for understanding the evolution of vertebrates. the elephant shark (callorhinchus milii), a holocephalan cartilaginous fish, has been identified as a model cartilaginous fish genome because of its compact genome (∼910 mb) and a genome project has been initiated to obtain its whole genome sequence. in this study, we have generated and sequenced full-length en ... | 2012 | 23056606 |
| identification of an mrap-independent melanocortin-2 receptor: functional expression of the cartilaginous fish, callorhinchus milii, melanocortin-2 receptor in cho cells. | phylogenetic analyses indicate that the genome of the cartilaginous fish, callorhynchus milii (elephant shark), encodes a melanocortin-2 receptor (mc2r) ortholog. expression of the elephant shark mc2r cdna in chinese hamster ovary (cho) cells revealed that trafficking to the plasma membrane and functional activation of the receptor do not require coexpression with an exogenous melanocortin receptor-2 accessory protein (mrap) cdna. ligand selectivity studies indicated that elephant shark mc2r-tra ... | 2012 | 22919056 |
| the fifth neurohypophysial hormone receptor is structurally related to the v2-type receptor but functionally similar to v1-type receptors. | the neurohypophysial peptides of the vasopressin (vp) and oxytocin (ot) families regulate salt and water homeostasis and reproduction through distinct g protein-coupled receptors. the current thinking is that there are four neurohypophysial hormone receptors (v1ar, v1br, v2r, and otr) in vertebrates, and their evolutionary history is still debated. we report the identification of a fifth neurohypophysial hormone receptor (v2br) from the holocephalan elephant fish. this receptor is similar to con ... | 2012 | 22809669 |
| first detection of taste buds in a chimaeroid fish (chondrichthyes: holocephali) and their gαi-like immunoreactivity. | the mucosa covering the tongue of the chimaera monstrosa has been investigated with histological and immunohistochemical methods allowing to describe, for the first time, gustatory structures (taste buds) in this subclass of cartilaginous fish. g-protein-alpha-subunit-inhibitory-like (gαi-like) immunoreactivity has been detected in the taste buds of c. monstrosa, as described in other vertebrates. in order to gain confidence on the antiserum used, able to recognize three gαi proteins in mammals, ... | 2012 | 22543113 |
| functional expression of squalus acanthias melanocortin-5 receptor in cho cells: ligand selectivity and interaction with mrap. | the melanocortin-5 receptor (mc(5)) of the dogfish squalus acanthias (sacmc(5) receptor) can be functionally expressed in cho cells in the absence of the co-expression of an exogenous mrap cdna. both human acth(1-24) and dogfish acth(1-25) were much better stimulators of the sacmc(5) receptor than any of the mammalian or dogfish msh ligands that were tested. the order of ligand selectivity for the dogfish melanocortins was acth(1-25)>αmsh>γ-msh=δ-msh>β-msh. unlike mammalian mc(5) receptors, the ... | 2012 | 22314217 |
| hepatic and extrahepatic distribution of ornithine urea cycle enzymes in holocephalan elephant fish (callorhinchus milii). | cartilaginous fish comprise two subclasses, the holocephali (chimaeras) and elasmobranchii (sharks, skates and rays). little is known about osmoregulatory mechanisms in holocephalan fishes except that they conduct urea-based osmoregulation, as in elasmobranchs. in the present study, we examined the ornithine urea cycle (ouc) enzymes that play a role in urea biosynthesis in the holocephalan elephant fish, callorhinchus milii (cm). we obtained a single mrna encoding carbamoyl phosphate synthetase ... | 2012 | 22227372 |
| conservation of all three p53 family members and mdm2 and mdm4 in the cartilaginous fish. | analysis of the genome of the elephant shark (callorhinchus milii), a member of the cartilaginous fishes (class chondrichthyes), reveals that it encodes all three members of the p53 gene family, p53, p63 and p73, each with clear homology to the equivalent gene in bony vertebrates (class osteichthyes). thus, the gene duplication events that lead to the presence of three family members in the vertebrates dates to before the silurian era. it also encodes mdm2 and mdm4 genes but does not encode the ... | 2011 | 22107961 |
| chondrichthyan egg cases from the south-west atlantic ocean. | egg cases of 21 oviparous chondrichthyan species from the south-west atlantic ocean are described and compared. the catshark schroederichthys bivius has a cigar-shaped egg case with curled tendrils only at the posterior end. egg cases of the elephant fish callorhinchus callorynchus are spindle-shaped with anterior and posterior tubular extensions and lateral flanges. the skate amblyraja doellojuradoi presents medium-sized egg cases (71 mm in length) with a lateral keel extending to the first por ... | 2011 | 22026605 |
| phylogenetic analysis reveals wide distribution of globin x. | the vertebrate globin gene repertoire consists of seven members that differ in terms of structure, function and phyletic distribution. while hemoglobin, myoglobin, cytoglobin, and neuroglobin are present in almost all gnathostomes examined so far, other globin genes, like globin x, are much more restricted in their phyletic distribution. till today, globin x has only been found in teleost fish and xenopus. here, we report that globin x is also present in the genomes of the sea lamprey, ghost sha ... | 2011 | 22004552 |
| identification of members of the gonadotropin-releasing hormone (gnrh), corticotropin-releasing factor (crf) families in the genome of the holocephalan, callorhinchus milii (elephant shark). | the gonadotropin-releasing hormone (gnrh) and corticotropin-releasing family (crf) are two neuropeptides families that are strongly conserved throughout evolution. recently, the genome of the holocephalan, callorhinchus milii (elephant shark) has been sequenced. the phylogenetic position of c. milii, along with the relatively slow evolution of the cartilaginous fish suggests that neuropeptides in this species may resemble the earliest gnathostome forms. the genome of the elephant shark was scree ... | 2011 | 21310155 |
| holocephalan embryos provide evidence for gill arch appendage reduction and opercular evolution in cartilaginous fishes. | chondrichthyans possess endoskeletal appendages called branchial rays that extend laterally from their hyoid and gill-bearing (branchial) arches. branchial ray outgrowth, like tetrapod limb outgrowth, is maintained by sonic hedgehog (shh) signaling. in limbs, distal endoskeletal elements fail to form in the absence of normal shh signaling, whereas shortened duration of shh expression correlates with distal endoskeletal reduction in naturally variable populations. chondrichthyans also exhibit nat ... | 2011 | 21220324 |
| parathyroid hormone gene family in a cartilaginous fish, the elephant shark (callorhinchus milii). | the development of bone was a major step in the evolution of vertebrates. a bony skeleton provided structural support and a calcium reservoir essential for the movement from an aquatic to a terrestrial environment. cartilaginous fishes are the oldest living group of jawed vertebrates. in this study we have identified three members of the parathyroid hormone (pth) gene family in a cartilaginous fish, the elephant shark (callorhinchus milii). the three genes include two pth genes, designated as pt ... | 2010 | 20614475 |
| loss of fish actinotrichia proteins and the fin-to-limb transition. | the early development of teleost paired fins is strikingly similar to that of tetrapod limb buds and is controlled by similar mechanisms. one early morphological divergence between pectoral fins and limbs is in the fate of the apical ectodermal ridge (aer), the distal epidermis that rims the bud. whereas the aer of tetrapods regresses after specification of the skeletal progenitors, the aer of teleost fishes forms a fold that elongates. formation of the fin fold is accompanied by the synthesis o ... | 2010 | 20574421 |
| g protein alpha subunits in the olfactory epithelium of the holocephalan fish chimaera monstrosa. | receptor neurons in the olfactory and vomeronasal epithelia of vertebrates have dendritic specialization that is correlated to the receptor gene family they express and the g protein coupled with that receptor (in particular the g protein alpha subunit). there are not very many data in the literature about the morphological and molecular features of the olfactory epithelium of chondrichthyes. in this work, the presence and distribution of different types of g protein alpha subunits (galpha(o), g ... | 2010 | 20122993 |
| multiple urea transporter proteins in the kidney of holocephalan elephant fish (callorhinchus milii). | reabsorption of filtered urea by the kidney is essential for retaining high levels of urea in marine cartilaginous fish. our previous studies on the shark facilitative urea transporter (ut) suggest that additional ut(s) comprising the urea reabsorption system could exist in the cartilaginous fish kidney. here, we isolated three cdnas encoding uts from the kidney of elephant fish, callorhinchus milii, and termed them efut-1, efut-2 and efut-3. efut-1 is orthologous to known elasmobranch uts, whil ... | 2009 | 19559810 |
| neuropeptide y-family peptides and receptors in the elephant shark, callorhinchus milii confirm gene duplications before the gnathostome radiation. | we describe here the repertoire of neuropeptide y (npy) peptides and receptors in the elephant shark callorhinchus milii, belonging to the chondrichthyans that diverged from the rest of the gnathostome (jawed vertebrate) lineage about 450 million years ago and the first chondrichthyan with a genome project. we have identified two peptide genes that are orthologous to npy and pyy (peptide yy) in other vertebrates, and seven receptor genes orthologous to the y1, y2, y4, y5, y6, y7 and y8 subtypes ... | 2009 | 18977429 |
| glial architecture of the ghost shark (callorhinchus milii, holocephali, chondrichthyes) as revealed by different immunohistochemical markers. | this article presents the first study on the glial architecture of a representative species of holocephali, callorhinchus milii (ghost shark). holocephali are a small subclass of chondrichthyes, with only a few extant genera, and those are considered to have a brain organization more similar to squalomorph sharks than to galeomorph sharks, skates, and rays. three different astroglial markers--glial fibrillary acidic protein, s-100 protein, and glutamine synthetase (gs)--were investigated by immu ... | 2008 | 18512702 |
| osmoregulation in elephant fish callorhinchus milii (holocephali), with special reference to the rectal gland. | osmoregulatory mechanisms in holocephalan fishes are poorly understood except that these fish are known to conduct urea-based osmoregulation as in elasmobranchs. we, therefore, examined changes in plasma parameters of elephant fish callorhinchus milii, after gradual transfer to concentrated (120%) or diluted (80%) seawater (sw). in control fish, plasma na and urea concentrations were about 300 mmol l(-1) and 450 mmol l(-1), respectively. these values were equivalent to those of sharks and rays, ... | 2007 | 17401114 |
| ultrastructure of sperm storage and male genital ducts in a male holocephalan, the elephant fish, callorhynchus milii. | in chondrichthyes, the process of spermatogenesis produces a spermatocyst composed of sertoli cells and their cohort of associated spermatozoa linearly arrayed and embedded in the apical end of the sertoli cell. the extratesticular ducts consist of paired epididymis, ductus deferens, isthmus, and seminal vesicles. in transit through the ducts, spermatozoa undergo modification by secretions of the extratesticular ducts and associated glands, i.e., leydig gland. in mature animals, the anterior por ... | 2002 | 11754028 |
| spontaneous contractions in elasmobranch vessels in vitro. | isolated vessels from four elasmobranchs, yellow stingray (urolophus jamaicensis), clearnose skate (raja eglanteria), ghost shark (hydrolagus novaezelandiae), and spiny dogfish (squalus acanthias), were examined for the presence of spontaneous contractions (sc). sc were observed in otherwise unstimulated dorsal aortas (da) from stingray and ghost shark, but not in skate da. unstimulated ventral aortas (va) did not exhibit sc. after treatment of va with a contractile agonist, sc appeared in sting ... | 2000 | 10766969 |
| anomalous electric organ discharges from the elephant fish, gnathonemus moori. | | 1970 | 5527542 |
| wounding by elephant fish. | | 1961 | 13712392 |