hagfishes

..By contrast, Haikouella does not fit the widespread belief that ancestral craniates resembled hagfishes, because it has no special hagfish characters...

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..origin of Col2A1 has been studied at the biochemical and molecular levels in extant jawless vertebrates (hagfishes and lampreys)...

The apparently primitive features of hagfishes are recognized as a crucial problem in the study of vertebrate evolution, although the monophyletic relationship between these animals and lampreys has been confirmed by large amounts of ..

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Heart muscles of hagfishes Paramyxine atami and Eptatretus okinoseanus express the B4 isozyme of lactate dehydrogenase [L-LDH: NAD oxidoreductase, EC 1.1.1.27] (LDH-B4) whereas their skeletal muscles express LDH-A4...

Extant vertebrates are divided into three major groups: hagfishes (Hyperotreti, myxinoids), lampreys (Hyperoartia, petromyzontids), and jawed vertebrates (Gnathostomata)...

..Here, we investigate the origin of vertebrate cartilage, and we report that hagfishes, the sister group to lampreys, also have Col2alpha1-based cartilage, suggesting its presence in the common ..

..The comparison of the mtDNAs of two M. glutinosa specimens, excluding the control region, shows a 0.6% divergence at the nucleotide level as a sample of intraspecies polymorphism...

Resolving the interrelationships of three major extant lineages of vertebrates (hagfishes, lampreys, and gnathostomes) is a particularly important issue in evolution, because the basal resolution critically influences our understanding ..

Due to their curious phylogenetic position and anatomy, hagfishes have attracted the interest of zoologists, especially in the context of vertebrate evolution...

b>Hagfishes are regarded as the most primitive living craniates. Excitation-contraction (E-C) coupling mechanisms were studied in skeletal and caudal heart muscle fibres of the hagfish Eptatretus burgeri...

..This clearly shows that nebulin is not exclusively present in skeletal muscles of chordates. The findings also demonstrate a rare case of dramatic size reduction of a protein during evolution...

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..Thus, the complexity of all the paralogy groups present in vertebrates should be explained by the contribution of genome duplications (2R hypothesis), extra gene duplications, and gene losses...

The Cyclostomata consists of the two orders Myxiniformes (hagfishes) and Petromyzoniformes (lampreys), and its monophyly has been unequivocally supported by recent molecular phylogenetic studies...

..It is likely that CD45 was recruited to activate lymphocytes through antigen receptors encoded by rearranging genes in jawed vertebrates...

..The high degree of sequence similarity between hfCNT and hCNT3 may indicate functional constraints on the primary structure of the transporter and suggests that cib-type CNTs fulfill important physiological functions...

..The gene tree suggests that the gene duplication event of PGI in bonyfishes occurred before diversification of Acanthopterygii but after the split of bonyfishes and tetrapods. The evolution of multiple functions of PGI is discussed...

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The phylogenetic position of cyclostomes, i.e., the relationships between hagfishes, lampreys, and jawed vertebrates is an unresolved problem...

..Our results show that a significant structural transition marks the protochordate to the Craniate evolutionary step, with the appearance of skeletal muscle-specific RyR and DHPR isoforms...

..These combine to shape a powerful multi-level and multi-causal selective scenario that I propose could have moulded the acquired immune system...

..It also reveals a high degree of convergent evolution among the members of the family. Finally, it suggests that the divergence of MIF and DDT occurred before the emergence of nematodes in metazoan evolution...

..In this paper we report the results of a PCR survey on genomic DNA of the pacific hagfish Eptatretus stoutii. Hagfishes are one of two clades of recent jawless fishes that are an offshoot of the early radiation of jawless ..

..In total, our work provides circumstantial evidence that adaptive immunity is unique to jawed vertebrates...

..This evidence strongly suggests that the hagfish defends itself against pathogens at least by the complement system composed of lectin pathway...

..We suggest that this tissue organization provides local defense of the hagfish gastrointestinal tract via innate immunity and possibly served as the architectural plan upon which the adaptive immune system evolved...

..glutinosa behaves as a true Ikaros family member. Taken together, these results indicate that the properties associated with the Ikaros family preceded the emergence of the jawed vertebrates and thus adaptive immunity...

..Phylogenetic analysis indicates that among known proteins, NICIR is most closely related to the lamprey molecule recently proposed to be a potential ancestor of T cell receptors...

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..The extracellular domain of APAR may be descended from a V-type domain postulated to have acquired recombination signal sequences in a jawed vertebrate lineage...

..Our results indicate that tight interactions can evolve by molecular exploitation-recruitment of an older molecule, previously constrained for a different role, into a new functional complex...

..This study revealed the long-term vertical inheritance and the ancient origin of sequence specificity of R2, both of which seem applicable to some other non-LTR retrotransposons...

..The development of two very different strategies for receptor diversification at the dawn of vertebrate evolution approximately 500 million years ago attests to the fitness value of a lymphocyte-based system of anticipatory immunity...

..These observations suggest that EbAQP4 is an ancestral water channel of mammalian AQP4 and plays a role in basolateral water transport in the gill pavement cells...

..This implies that the specific subunit cleavage at Arg833 was caused by an unknown arginine specific proteinase which escaped from the entrapment by the hagfish inhibitor...

..They belong to the rhodopsin family of G protein-coupled receptors (GPCRs). The purpose of this study was to identify ancestral MC receptors in agnathan, river lamprey...

..Our results therefore suggest that the formation of the alpha2beta2 tetramer using the BGH core and the mechanism of quaternary structure change evolved between the branching points of hagfish and lampreys from other vertebrates...

..Here, we report the mapping of a ParaHox gene cluster in 2 species of hagfishes. Unexpectedly, these basal vertebrates have lost a functional Xlox gene from this cluster, unlike every other ..

..The interaction with Eritoran is mediated by a hydrophobic internal pocket in MD-2. Based on structural analysis and mutagenesis experiments on MD-2 and TLR4, we propose a model of TLR4-MD-2 dimerization induced by LPS...

..The vitamin K-dependent biosynthesis of gamma-carboxyglutamic acid appears to be a highly conserved function in the animal kingdom...

..Helix modeling of hCNT1 placed Ser(319) (TM 7) and Ser(353) (TM 8) within the putative substrate translocation channel, whereas Gln(320) (TM 7) and Leu(354) (TM 8) may exert their effects through altered helix packing...

Cyclostomes, hagfishes and lampreys, contain hemoglobins that are monomeric when oxygenated and polymerize to dimers or tetramers when deoxygenated...

..The similarities in expression patterns of Runt genes support the view that teeth and placoid scales evolved from a homologous developmental module...

..Extant agnathans are represented by hagfishes (Myxiniformes) and lampreys (Petromyzontiformes), frequently grouped together within the Cyclostomata...

..Almost all of these vitronectin-like proteins showed marked species-specific variations in their apparent molecular weights from 51 to 96 kDa in SDS-PAGE...

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..This suggests that specialized functions for each of these orthology classes were fixed in the gnathostome lineage prior to the splitting between osteichthyans and chondrichthyans...

..We compared the activities of lactate dehydrogenase (LDH), an important enzyme in glycolytic reaction, in three hagfishes inhabiting different depths under increased pressure...

..We conclude that the delaminating neural crest is a vertebrate synapomorphy that seems to have appeared from the beginning of their evolutionary history, before the splitting away of the hagfish lineage...

..From these results, we hypothesize that hagfish have functional corpora lutea like structures that produce progesterone...

..Molecular 16S rRNA data places this new species as the basal-most species of Eptatretus, providing important new insight to the evolution of hagfishes as a whole.

b>Hagfishes have long held a key place in discussions of early vertebrate evolution...

..Results of this study suggest that modification of GRIA2 transcripts by Q/R editing is most likely acquired after the separation of the Agnatha and Gnathostome...

..Thus, a certain part of genome with a particular size and structure may serve for genetic isolation of species as shellfish or junk DNA are vital components rather than pieces of garbage...

..These data are some of the first direct evidence of NHEs in the gills of an agnathan and elasmobranch, and confirm the presence of NHEs in the gills of teleosts...

..bootstrapping, include: (1) brittle star joins with sea star in the echinoderm clade, Asterozoa; (2) with two hagfishes and two lampreys now available, the cyclostome (jawless) fishes remain monophyletic; (3) Hexanchiform sharks are ..

..Thus, we demonstrated the common occurrence of four MSHs in chondrichthian POMC and established a clear understanding of the molecular evolution of POMC in gnathostomes...

..All vertebrates, with the exception of hagfishes, have taste buds...

..Protein sequencing of the trout C3 fragments fixed on zymosan during complement activation confirmed the cleavage of trout C3 by trout C3 convertase and factor I at Arg-Ser and Arg-Thr, respectively...

Lampreys, together with hagfishes, represent the sister group of gnathostome vertebrates...

The agnathans (lampreys and hagfishes) are representatives of the jawless fishes and constitute the first lineage of extant vertebrates to evolve within chordate phylogenetic history...

..The hCNT3 gene mapped to chromosome 9q22.2 and included an upstream phorbol myristate acetate response element...

..Agnathan fish such as hagfish and lamprey may be interesting model species for examining possible ancestral AHR functions not related to CYP1A regulation...

..These results are compared with those of other vertebrates, and potential roles for these substances in the control of catecholamine release are suggested...

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..It is also likely that the cardioprotective role of NPs was one of the most primordial homeostatic activities of these peptides in the earliest vertebrates...

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The jawless Agnatha (lampreys and hagfishes) represent the phylogenetically oldest order of vertebrates that are believed to lack the adaptive immune system of jawed vertebrates...

..Our results provide the first evidence of a jawless vertebrate, represented today solely by the lampreys and hagfishes, with two morphologically and physiologically distinct types of cone photoreceptors, in addition to a rod-like ..

..e., hagfishes and lampreys)...

..These results provide preliminary information for a better understanding of the role of epidermal mucus and its components in the fish innate immune system...

b>Hagfishes are benthic marine protovertebrates that secrete copious quantities of slime when threatened...

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..Four discrete decasaccharide epitopic sequences were identified. The antibody GD3G7 has broad applications in investigations of CS/DS chains during the central nervous system's development and under various pathological conditions...

..Here, we summarize in vitro measurements of PO data from rainbow trout, freshwater turtles and hagfishes to provide a reasonable benchmark PO of 0...

..Validating this premise will require better characterization of the genome sequence and mechanisms of rearrangement in lamprey and hagfish...

Extant jawless vertebrates, represented by lampreys and hagfishes, have innate immune receptors with variable domains structurally resembling T/B-cell receptors...

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Jawless fishes (Agnatha; lampreys and hagfishes) most closely resemble the earliest stage in vertebrate evolution and lamprey-like animals already existed in the Lower Cambrian [about 540 million years ago (MYA)]...

Lampreys are a group of aquatic chordates whose relationships to hagfishes and jawed vertebrates are still debated. Lamprey embryology is of interest to evolutionary biologists because it may shed light on vertebrate origins...

..6 to 6.6 folds lower for human pathogens. This preliminary information suggests that the mucus from these fish species may be a source of novel antimicrobial agents for fish and human health related applications...

..We found that most major lineages of deuterostomes arose prior to the Cambrian Explosion of fossils (approximately 520 MYA) and that several lineages had originated before periods of global glaciation in the Precambrian...

In the absence of any previous study of the cardiac status of hagfishes during prolonged anoxia and because of their propensity for oxygen-depleted environments, the present study tested the hypothesis that the Pacific hagfish Eptatretus ..

It is generally accepted that living jawless vertebrates (lampreys and hagfishes) lack the capability of mounting an adaptive immune response...

..is intimately bound up with vertebrate evolution: the most primitive living vertebrates, lampreys and hagfishes, have most but not all neural crest derivatives...

..The hagfish sequence showed low conservation with the mammalian opioid receptors in the first and second extracellular loops but high conservation in the transmembrane and intracellular domains...

..To understand better the evolution of adaptive immune systems, more comparative data from jawless vertebrates (lamprey or hagfish) and a representative of Acrania (e.g. Amphioxus) are clearly needed...

Although hagfishes are ecologically important members of benthic communities there has been little data available on their metabolism...

..The effects of high hydrostatic pressure from 0.1 to 100 MPa on LDH activities from three hagfishes were examined. The LDH activities of Eptatretus burgeri, living at 45-60 m, were completely lost at 5 MPa...

..The agnathan hagfishes have primitive gill pouches, while the lampreys have arch-like gills similar to the higher fishes...

..The length and sequence of the L1 of teleost GRIA1 subunits were heterogeneous, suggesting that the amino acid residues in L1 were not highly selected...

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..This suggests that some other mechanism such as the chemical microenvironment within gland mucous cells, or hydrostatic pressure is responsible for stabilization of the vesicles within the gland...

..We conclude that conodonts are cladistically more derived than either hagfishes or lampreys because they possess a mineralised dermal skeleton and that they are the most plesiomorphic member ..

..Using mammal and fish models may be more appropriate than avian models because of the apparent evolution of a novel reaction to tensile loads in birds...

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..Experiments to evaluate the specificity and peptide complex-dependency of these putative alloimmune reactivities are presented as are experiments to reveal the nature of effector cells involved. ..

..The experiments proposed here will define biological and structural features of the VLRs in order to explore their potential for health-related uses. ..

..The experiments proposed here will define biological and structural features of the VLRs in order to explore their potential for health-related uses. ..

..The experiments proposed here will define biological and structural features of the VLRs in order to explore their potential for health-related uses. ..

..These sites are predicted to provide ideal targets for therapeutic interventions for heart and kidney disease. ..

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..We will, therefore, determine whether RAG-1 is present in representative Agnatha (hagfish and lamprey); its identification would justify renewed efforts to characterize the immune system of these primitive vertebrates...

..I will use a combination of molecular biology, forward and reverse genetic analyses, and patch clamp electrophysiology to identify GCK-3 signaling components. ..

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..Colin Barnstable, Professor of Neurobiology and Ophthalmology, who is an internationally recognized molecular biologist using mouse models of retinal development and degeneration. ..

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..Studying these phenomena will help determine parameters for genetic exchange between non-allelic genes and give insight into the origins of somatic translocation events leading to disease states. ..

..These studies will provide a better understanding of the possible role of human AHRR in modulating dioxin effects. ..

..Studying the lamprey genome is a touchstone for understanding genes that arose in the vertebrates and offers an innovative approach to therapeutic research. ..

..These studies are aimed at determining the degree of specificity involved in the assembly of fibrin units and protofibrils as well as the relative locations of the regions involved. ..

..This comparative analysis will define novel features of B cell differentiationthat are likely to have significant clinical implications. ..

..Additional experimental neuroanatomical studies on the organization of the gustatory system of juvenile and adult axolotls will also be conducted in order to provide a more complete picture of this system...

..These experiments should begin to unravel the complex interactions of the tissues that form the vertebrate head, and they are a necessary preamble to identifying the molecular signals underlying the development of the gustatory system. ..

..To test the hypothesis that retinoic acid acts as a signal to pattern endoderm directly during gastrulation (aim 3), presumptive pharyngeal endoderm will be excised, exposed to retinoic acid, and cultured. ..

..Combined with the full structures of the native molecules at high resolution, these results should dispel much of the mystery of fibrin formation. ..