hagfish

Hagfish (Myxinoidea) are a deep-sea taxon of cyclostomes, the extant jawless vertebrates. Many researchers have examined the anatomy and embryology of hagfish to shed light on the early evolution of vertebrates; however, the diversity within hagfish is often overlooked. Hagfish have three lineages, Myxininae, Eptatretinae, and Rubicundinae. Usually, textbook illustrations of hagfish anatomy reflect the morphology of the Myxininae lineage, especially Myxine glutinosa, with its single pair of external branchial pores...

When attacked, hagfishes produce a soft, fibrous defensive slime within a fraction of a second by ejecting mucus and threads into seawater. The rapid setup and remarkable expansion of the slime make it a highly effective and unique form of defense. How this biomaterial evolved is unknown, although circumstantial evidence points to the epidermis as the origin of the thread- and mucus-producing cells in the slime glands. Here, we describe large intracellular threads within a putatively homologous cell type from hagfish epidermis...

Vertebrate neurohypophysial hormones, i.e., vasopressin- and oxytocin-family peptides, exert versatile physiological actions via distinct G protein-coupled receptors. The neurohypophysial hormone receptor (NHR) family was classically categorized into four subtypes (V1aR, V1bR, V2R and OTR), while recent studies have identified seven subtypes (V1aR, V1bR, V2aR, V2bR, V2cR, V2dR and OTR; V2aR corresponds to the conventional V2R). The vertebrate NHR family were diversified via multiple gene duplication events at different scales...

A new species of the hagfish genus Eptatretus (Myxinidae) is described based on two specimens (407-433 mm LT ) collected off northern Bahamas, between depths of 910 and 1153 m. The new species is distinguished from its congeners by having: seven pairs of gill apertures well-spaced and arranged in a near straight line; a 3/2 multicusp pattern of teeth; 10-11 anterior unicusps; 50-51 total cusps; 12-14 prebranchial pores; 48-52 trunk pores; 79-84 total pores; and no nasal-sinus papillae. An identification key for the species of Eptatretus from the western Atlantic Ocean is also provided...

Inflammation is a physiological reaction of the immune system required to remove the presence of pathogenic germs. Many herbal-derived extracts and phytoconstituents show anti-inflammatory effects. Among these natural phytoconstituents is Ephedra alte ( E. alte ), which shows pepsin enzyme inhibitory, antibacterial, and antioxidant activities. In this work, molecular docking study is conducted on five major human anti-inflammatory cytokines receptors (IL-6, hybrid TLR4, TNF-α, IL-1β, and extracted TLR4) to explore the molecular recognition process and complex ligand-receptor interactions of E...

The development of a movable jaw is one of the most important transitions in the evolutionary history of animals.1 Jawed vertebrates rapidly diversified after appearing approximately 470 million years ago. Today, only lampreys and hagfishes represent the once dominant jawless grade2 , 3 , 4 and comprise less than 1% of living vertebrate species. Their relationship to other vertebrates ranks among the more contentious problems in animal phylogenetics.5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 Further, the phylogenetic relationships within lampreys and hagfishes remain unclear,13 , 14 , 15 and the ages of their living lineages are largely unexplored...

There is an urgent need to improve the sustainability of the materials we produce and use. Here, we explore what humans can learn from nature about how to sustainably fabricate polymeric fibers with excellent material properties by reviewing the physical and chemical aspects of materials processing distilled from diverse model systems, including spider silk, mussel byssus, velvet worm slime, hagfish slime, and mistletoe viscin. We identify common and divergent strategies, highlighting the potential for bioinspired design and technology transfer...

In the Japanese hagfish Eptatretus burgeri, 16 chromosomes (eliminated [E]-chromosomes) have been lost in somatic cells (2n = 36), which is equivalent to approx. 21% of the genomic DNA in germ cells (2n = 52). At least seven of the 12 eliminated repetitive DNA families isolated in eight hagfish species were selectively amplified in the germline genome of this species. One of them, EEEb1 (eliminated element of E. burgeri 1) is exclusively localized on all E-chromosomes. Herein, we identified four novel eliminated repetitive DNA families (named EEEb3-6) through PCR amplification and suppressive subtractive hybridization (SSH) combined with Southern-blot hybridization...

The acquisition of movable jaws was a major event during vertebrate evolution. The role of NK3 homeobox 2 (Nkx3.2) transcription factor in patterning the primary jaw joint of gnathostomes (jawed vertebrates) is well known, however knowledge about its regulatory mechanism is lacking. In this study, we report a proximal enhancer element of <i>Nkx3.2</i> that is deeply conserved in most gnathostomes but undetectable in the jawless hagfish and lamprey. This enhancer is active in the developing jaw joint region of the zebrafish <i>Danio rerio</i>, and was thus designated as <i>jaw joint regulatory sequence 1</i> (JRS1)...

New material of the tridensaspid Pterogonaspis yuhaii is described from the Xujiachong Formation in Qujing City, Yunnan Province, revealing the morphology of the ventral side of the headshield for the first time. Most significantly, the cranial anatomy of Pterogonaspis provides the first fossil evidence for the position of the esophagus in galeaspids. The esophagus and dorsal aortae display a central placement in the postbranchial region and do not share a common canal as in osteostracans. Moreover, the paired and symmetrically extending dorsal aortae in galeaspids strikingly resemble those of jawed vertebrates, probably representing a plesiomorphic condition for vertebrates because they are also present in amphioxus and hagfishes...

The fish intestine operates as a complicated interface between the organism and the environment, providing biological and mechanical protections as a result of a viscous layer of mucus released by goblet cells, which serves as a barrier against bacteria, viruses, and other pathogens, and contributes to the functions of the immune system. Therefore, goblet cells have a role in preserving the health of the body by secreting mucus and acting as sentinels. The ancient jawless fish broadgilled hagfish ( Eptatretus cirrhatus , Forster, 1801) has a very basic digestive system because it lacks a stomach...

Pacific hagfish (Eptatretus stoutii) are marine scavengers and feed on decaying animal carrion by burrowing their bodies inside rotten carcasses where they are exposed to several threatening environmental stressors, including hypercapnia (high partial pressures of CO2 ). Hagfish possess a remarkable capacity to tolerate hypercapnia, and their ability to recover from acid-base disturbances is well known. To deal with the metabolic acidosis resulting from exposure to high CO2 , hagfish can mount a rapid elevation of plasma HCO3 - concentration (hypercarbia)...

A new species of hagfish, Eptatretus wadgensis sp. nov., is described from the Wadge Bank, Lakshadweep Sea, India, obtained from a depth of ~250300 m through deep-sea trawling. It is diagnosed by having six pairs of gill pouches and gill apertures, 3/3 multicusp teeth, total slime pores 6769, six branchial slime pores, and ventral aorta bifurcating at the 4th or between 4th and 5th gill pouch. The new species has significant morphological differences in total dental cusps, total slime pores, body proportions and the absence of the nasal-sinus papilla when compared to congeners and formed a distinct clade in phylogenetic reconstruction and a genetic distance of 3...

The purpose of this study was to determine a method to purify recombinant hagfish intermediate filament proteins, alpha and gamma, in a scalable manner. The study succeeded by having an increase in protein recovery of up to 35% when comparing centrifuge purification and the developed tangential flow purification. The proteins were approximately the same purity of 70% pure but further purification increased the purity of the proteins by 16%, based on ImageJ analysis. The developed tangential flow filtration purification and final purification methods could be easily scaled up to meet industry scale purification needs...

Hagfish slime proteins have long been considered useful due to their potential applications in novel green, environmental, and functional bionic materials. The two main component proteins in the slime thread of hagfish, (opt)EsTKα and (opt)EsTKγ, were used as raw materials. However, the methods available to assemble these two proteins are time- and labor-intensive. The conditions affecting protein self-assembly, such as the pH of the assembly buffer, protein concentration, and the protein addition ratio, were the subject of the present research...

BACKGROUND: The group XIV of C-type lectin domain-containing proteins (CTLDcps) is one of the seventeen groups of CTLDcps discovered in mammals and composed by four members: CD93, Clec14A, CD248 and Thrombomodulin, which have shown to be important players in cancer and vascular biology. Although these proteins belong to the same family, their phylogenetic relationship has never been dissected. To resolve their evolution and characterize their protein domain composition we investigated CTLDcp genes in gnathostomes and cyclostomes and, by means of phylogenetic approaches as well as synteny analyses, we inferred an evolutionary scheme that attempts to unravel their evolution in modern vertebrates...

AIM: Pacific hagfish are exceptionally tolerant to high environmental ammonia (HEA). Here, we elucidated a cellular mechanism that enables hagfish to actively excrete ammonia against steep ammonia gradients expected to be found inside a decomposing whale carcass. METHODS: Hagfish were exposed to varying concentrations of HEA in the presence or absence of environmental Na+ , while plasma ammonia levels were tracked. 14 C-methylammonium was used as a proxy for NH4 + to measure efflux in whole animals and in isolated gill pouches; the latter allowed us to assess the effects of amiloride specifically on Na+ /H+ exchangers (NHEs) in gill cells...

NF-Y is a trimeric pioneer Transcription Factor (TF) whose target sequence -the CCAAT box- is present in ~25% of mammalian promoters. We reconstruct the phylogenetic history of the regulatory NF-YA subunit in vertebrates. We find that in addition to the remarkable conservation of the subunits-interaction and DNA-binding parts, the Transcriptional Activation Domain (TAD) is also conserved (>90% identity among bony vertebrates). We infer the phylogeny of the alternatively spliced exon-3 and partial splicing events of exon-7 -7N and 7C- revealing independent clade-specific losses of these regions...

Corticosteroids are synthesized from cholesterol by steroidogenic enzyme catalysts belonging to two main families: the cytochrome p450s (CYPs) and hydroxysteroid dehydrogenases (HSDs). The action of these steroidogenic enzymes allows the genesis of the terminal active corticosteroids 11-deoxycortisol (S), 1ɑ-hydroxycorticosterone (1α-OH-B), or cortisol in different fish species. However, for Cyclostomes like hagfishes, the terminal corticosteroid is still undefined. In this study, we examined the presence or absence of CYPs and HSDs as traits in fishes to gain insight about the primary corticosteroid synthesis pathways of the hagfishes...

Early in vertebrate evolution, a single homeobox (Hox) cluster in basal chordates was quadrupled to generate the Hox gene clusters present in extant vertebrates. Here we ask how this expanded gene pool may have influenced the evolution of the visual system. We suggest that a single neurosensory cell type split into ciliated sensory cells (photoreceptors, which transduce light) and retinal ganglion cells (RGC, which project to the brain). In vertebrates, development of photoreceptors is regulated by the basic helix-loop-helix (bHLH) transcription factor Neurod1 whereas RGC development depends on Atoh7 and related bHLH genes...