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Ahvo A, Lehtonen KK, Lastumäki A, Straumer K, Kraugerud M, Feist SW, Lang T, Tørnes JA. The use of Atlantic hagfish (Myxine glutinosa) as a bioindicator species for studies on effects of dumped chemical warfare agents in the Skagerrak. 2. Biochemical biomarkers. MARINE ENVIRONMENTAL RESEARCH 2020; 162:105097. [PMID: 32992222 DOI: 10.1016/j.marenvres.2020.105097] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 06/30/2020] [Accepted: 07/30/2020] [Indexed: 06/11/2023]
Abstract
The sea bottom of the Skagerrak Strait (North Sea) contains munitions loaded with chemical warfare agents (CWA), mostly stored in shipwrecks scuttled intentionally after the end of the World War II. The munition shells inside the wrecks are in different states of deterioration and corrosion and their environmental risk potential is unknown. The Atlantic hagfish (Myxine glutinosa), a sediment-dwelling chordate, was used as a model organism to study the potential impact of dumped CWA on the local ecosystem by using biochemical biomarkers. The hagfish were collected in 2017 and 2018 at three sampling sites: in the immediate vicinity of a wreck with CWA in the Skagerrak, a few kilometres from the wreck, and a reference site 21 km from the wreck, considered to be free of CWA. Significant differences were observed between the wreck site and the reference sites in the activities of glutathione reductase, superoxide dismutase and glutathione S-transferase, while the activity levels of catalase and acetylcholinesterase were identical at all sites. The recorded differences demonstrated negative biological effects in the hagfish sampled close to the dumped chemical munitions. Due to the limited knowledge of hagfish biology and of the extent of CWA contamination in Skagerrak, the results presented here warrant more research to further elucidate the potential environmental risks of the scuttled wrecks. The usefulness of the species as a bioindicator organism is further discussed.
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Affiliation(s)
- A Ahvo
- Finnish Environment Institute, Marine Research Centre, Agnes Sjöbergin Katu 2, 00790, Helsinki, Finland.
| | - K K Lehtonen
- Finnish Environment Institute, Marine Research Centre, Agnes Sjöbergin Katu 2, 00790, Helsinki, Finland
| | - A Lastumäki
- Finnish Environment Institute, Marine Research Centre, Agnes Sjöbergin Katu 2, 00790, Helsinki, Finland
| | - K Straumer
- Thünen Institute of Fisheries Ecology, Herwigstrasse 31, 27527, Bremerhaven, Germany
| | - M Kraugerud
- FishVet Group, Benchmark Norway AS, P. O. Box 1012, 0218, Oslo, Norway
| | - S W Feist
- Centre for Environment, Fisheries and Aquaculture Science, Weymouth Laboratory, Barrack Road, The Nothe, Weymouth, Dorset, DT4 8UB, UK
| | - T Lang
- Thünen Institute of Fisheries Ecology, Herwigstrasse 31, 27527, Bremerhaven, Germany
| | - J A Tørnes
- Norwegian Defence Research Establishment, Instituttveien 20, 2007, Kjeller, Norway
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Nozaki M. Hypothalamic-pituitary-gonadal endocrine system in the hagfish. Front Endocrinol (Lausanne) 2013; 4:200. [PMID: 24416029 PMCID: PMC3874551 DOI: 10.3389/fendo.2013.00200] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Accepted: 12/17/2013] [Indexed: 11/26/2022] Open
Abstract
The hypothalamic-pituitary system is considered to be a seminal event that emerged prior to or during the differentiation of the ancestral agnathans (jawless vertebrates). Hagfishes as one of the only two extant members of the class of agnathans are considered the most primitive vertebrates known, living or extinct. Accordingly, studies on their reproduction are important for understanding the evolution and phylogenetic aspects of the vertebrate reproductive endocrine system. In gnathostomes (jawed vertebrates), the hormones of the hypothalamus and pituitary have been extensively studied and shown to have well-defined roles in the control of reproduction. In hagfish, it was thought that they did not have the same neuroendocrine control of reproduction as gnathostomes, since it was not clear whether the hagfish pituitary gland contained tropic hormones of any kind. This review highlights the recent findings of the hypothalamic-pituitary-gonadal endocrine system in the hagfish. In contrast to gnathostomes that have two gonadotropins (GTH: luteinizing hormone and follicle-stimulating hormone), only one pituitary GTH has been identified in the hagfish. Immunohistochemical and functional studies confirmed that this hagfish GTH was significantly correlated with the developmental stages of the gonads and showed the presence of a steroid (estradiol) feedback system at the hypothalamic-pituitary levels. Moreover, while the identity of hypothalamic gonadotropin-releasing hormone (GnRH) has not been determined, immunoreactive (ir) GnRH has been shown in the hagfish brain including seasonal changes of ir-GnRH corresponding to gonadal reproductive stages. In addition, a hagfish PQRFamide peptide was identified and shown to stimulate the expression of hagfish GTHβ mRNA in the hagfish pituitary. These findings provide evidence that there are neuroendocrine-pituitary hormones that share common structure and functional features compared to later evolved vertebrates.
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Affiliation(s)
- Masumi Nozaki
- Sado Marine Biological Station, Faculty of Science, Niigata University, Sado, Japan
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Nozaki M, Uchida K, Honda K, Shimotani T, Nishiyama M. Effects of estradiol or testosterone treatment on expression of gonadotropin subunit mRNAs and proteins in the pituitary of juvenile brown hagfish, Paramyxine atami. Gen Comp Endocrinol 2013; 189:111-8. [PMID: 23684771 DOI: 10.1016/j.ygcen.2013.04.034] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Revised: 04/25/2013] [Accepted: 04/27/2013] [Indexed: 11/26/2022]
Abstract
A single functional gonadotropin (GTH) comprising two subunits, α and β, was recently identified in the pituitary of brown hagfish (Paramyxine atami). Little is known about the feedback mechanisms that regulate these GTH subunits by sex steroids in the hagfish. The present study was designed to examine feedback effects of estradiol and testosterone on mRNA expression and protein expression of both GTHα and GTHβ subunits in the pituitary of the juvenile P. atami. Intraperitoneal administration of estradiol over the course of 27days resulted in substantial accumulation of immunoreactive (ir)-GTHα and ir-GTHβ in the adenohypophysis, but testosterone treatments over 27days had no effects on ir-GTHα or ir-GTHβ. Estradiol treatment for 1, 2, 4 or 14days had no effect on GTHα mRNA levels. In contrast, after 2days of estradiol treatment, GTHβ mRNA levels had increased significantly from baseline, while these levels were not affected after treatment over 1, 4, or 14days. After 14days of testosterone treatment, both GTHα and GTHβ mRNA levels had decreased significantly from baseline levels. These results indicate that estradiol acted primarily to suppress the secretion of GTH, and hence resulted in the accumulations of ir-GTHα and ir-GTHβ in the pituitary. On the other hand, testosterone appeared to suppress both the synthesis and the secretion of GTH. Thus, estradiol and testosterone probably differ in their effects on the regulation of pituitary GTH synthesis and secretion in juvenile hagfish.
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Affiliation(s)
- Masumi Nozaki
- Sado Marine Biological Station, Faculty of Science, Niigata University, Tassha, Sado, Niigata 952-2135, Japan.
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Uchida K, Moriyama S, Sower SA, Nozaki M. Glycoprotein hormone in the pituitary of hagfish and its evolutionary implications. FISH PHYSIOLOGY AND BIOCHEMISTRY 2013; 39:75-83. [PMID: 22614069 DOI: 10.1007/s10695-012-9657-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Accepted: 05/05/2012] [Indexed: 06/01/2023]
Abstract
The pituitary gland is present in all vertebrates, from agnathans (jawless vertebrates) to mammals, but not in invertebrates. Reproduction in gnathostomes (jawed vertebrates) is controlled by two pituitary gonadotropins (GTHs), luteinizing hormone and follicle-stimulating hormone, which are part of the pituitary glycoprotein hormone (GPH) family. Hagfishes, which lack both jaws and vertebrae, are considered the most primitive vertebrate known, living or extinct. Accordingly, they are of particular importance in understanding the evolution of the pituitary GPHs and their functions related to vertebrate reproduction. Nevertheless, key elements of the reproductive endocrine system in hagfish have yet to be elucidated. Our current report has revealed the first identification of a functional GPH composed of two subunits that possess gonadotropic action at the pituitary of brown hagfish. It seems most likely that an ancestral GPH gave rise to only one GTH in hagfish pituitary and that multiplicity of GPHs arose later during the early evolution of gnathostomes. This paper briefly summarizes the latest findings on the hagfish GPH from an evolutionary point of view.
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Affiliation(s)
- Katsuhisa Uchida
- Department of Marine Biology and Environmental Sciences, Faculty of Agriculture, University of Miyazaki, Miyazaki, 889-2192, Japan.
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Osugi T, Uchida K, Nozaki M, Tsutsui K. Characterization of novel RFamide peptides in the central nervous system of the brown hagfish: isolation, localization, and functional analysis. Endocrinology 2011; 152:4252-64. [PMID: 21862614 DOI: 10.1210/en.2011-1375] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
RFamide (RFa) peptides play various important roles in the central nervous system in both invertebrates and vertebrates. However, there is no evidence of the existence of any RFamide peptide in the brain of hagfish, one of the oldest lineages of vertebrates. In this study, we sought to identify novel RFamide peptides from the brains of hagfish (Paramyxine atami). We identified four novel RFamide peptides, which had the C-terminal Pro-Gln-Arg-Phe-NH2 structure. cDNA cloning revealed that the identified RFamide peptides are encoded in two types of cDNA. Molecular phylogenetic analysis of the two precursors indicated that the hagfish RFamide peptides belong to the PQRFamide peptide group that includes mammalian neuropeptide FF and AF. Based on immunohistochemistry and in situ hybridization, hagfish PQRFamide peptide precursor mRNA and its translated peptides were localized in the infundibular nucleus of the hypothalamus. Immunoreactive fibers were terminated on blood vessels in the infundibular nucleus. Dense immunoreactive fibers were also observed in other brain regions. We further showed that one of the hagfish PQRFamide peptides significantly stimulated the expression of gonadotropin-β mRNA in the cultured hagfish pituitary. These results indicate that the control mechanism of gonadotropin expression by a hypothalamic neuropeptide evolved in the agnathan brain. This is the first evidence describing the identification of RFamide peptides in the hagfish brain. This is also the first report showing the regulation of gonadotropin expression by a homolog of neuropeptide FF that belongs to the PQRFamide peptide group in any vertebrate.
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Affiliation(s)
- Tomohiro Osugi
- Laboratory of Integrative Brain Sciences, Department of Biology, Waseda University, Center for Medical Life Science of Waseda University, 2-2 Wakamatsu-cho, Shinjuku-.ku, Tokyo 162-8480, Japan
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Evolutionary origin of a functional gonadotropin in the pituitary of the most primitive vertebrate, hagfish. Proc Natl Acad Sci U S A 2010; 107:15832-7. [PMID: 20733079 DOI: 10.1073/pnas.1002208107] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Hagfish, which lack both jaws and vertebrae, are considered the most primitive vertebrate known, living or extinct. Hagfish have long been the enigma of vertebrate evolution not only because of their evolutionary position, but also because of our lack of knowledge on fundamental processes. Key elements of the reproductive endocrine system in hagfish have yet to be elucidated. Here, the presence and identity of a functional glycoprotein hormone (GPH) have been elucidated from the brown hagfish Paramyxine atami. The hagfish GPH consists of two subunits, alpha and beta, which are synthesized and colocalized in the same cells of the adenohypophysis. The cellular and transcriptional activities of hagfish GPHalpha and -beta were significantly correlated with the developmental stages of the gonad. The purified native GPH induced the release of gonadal sex steroids in vitro. From our phylogenetic analysis, we propose that ancestral glycoprotein alpha-subunit 2 (GPA2) and beta-subunit 5 (GPB5) gave rise to GPHalpha and GPHbeta of the vertebrate glycoprotein hormone family, respectively. The identified hagfish GPHalpha and -beta subunits appear to be the typical gnathostome GPHalpha and -beta subunits based on the sequence and phylogenetic analyses. We hypothesize that the identity of a single functional GPH of the hagfish, hagfish GTH, provides critical evidence for the existence of a pituitary-gonadal system in the earliest divergent vertebrate that likely evolved from an ancestral, prevertebrate exclusively neuroendocrine mechanism by gradual emergence of a previously undescribed control level, the pituitary, which is not found in the Protochordates.
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Nozaki M. The Hagfish Pituitary Gland and Its Putative Adenohypophysial Hormones. Zoolog Sci 2008; 25:1028-36. [DOI: 10.2108/zsj.25.1028] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Abstract
The use of steroids and their receptors as ligand-gated transcription factors is thought to be an important step in vertebrate evolution. The lamprey is the earliest-evolving vertebrate to date in which sex steroids and their receptors have been demonstrated to have hormonal roles similar to those found in jawed vertebrates. Sex steroids and their receptors have been examined in several lamprey species, and the majority of studies have focused on the sea lamprey, Petromyzon marinus. While classical steroids appear to be present in lampreys, their function, concentrations, and synthesis have not been determined conclusively. The only classical steroid that is thought to act as a hormone in both males and females is estradiol. Recent research has established that lampreys produce and circulate 15alpha-hydroxylated steroids, and that these steroids respond to upstream stimulation within the hypothalamic-pituitary-gonadal axis. In particular, 15alpha-hydroxyprogesterone is highly sensitive and responds in great magnitude to stimulation, and is likely a hormone. Lampreys also appear to use androstenedione, a precursor to vertebrate androgens, as their main androgen, and a receptor for androstenedione has recently been described. Non-classical steroids are prevalent in many aquatic vertebrates, and the non-classical steroids found in the sea lamprey may represent an evolutionary artifact, or alternatively may be a way to avoid endocrine disruption when ingesting the body fluids of host fish. The lamprey will continue to be an interesting model for examining the evolution of steroid hormones, steroid receptors, and steroid function.
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Affiliation(s)
- Mara B Bryan
- Department of Fisheries and Wildlife, Michigan State University, East Lansing, MI 48824, USA.
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A. Khalil N, E. El-Gama AEH, A. Gaber S, A. Mousa M. Immunohistochemical Localization of Gonadotropin-Releasing Hormone and Somatolactin During Sexual Maturation and Spawning of Lates niloticus. ACTA ACUST UNITED AC 2007. [DOI: 10.3923/jbs.2007.1102.1111] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Nozaki M, Shimotani T, Uchida K. Gonadotropin-like and adrenocorticotropin-like cells in the pituitary gland of hagfish, Paramyxine atami; immunohistochemistry in combination with lectin histochemistry. Cell Tissue Res 2007; 328:563-72. [PMID: 17347815 DOI: 10.1007/s00441-006-0349-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2006] [Accepted: 09/19/2006] [Indexed: 10/23/2022]
Abstract
The pituitary system of the hagfish remains an enigma. The present study has aimed to detect possible adenohypophysial hormones in the pituitary gland of the brown hagfish, Paramyxine atami, by means of immunohistochemistry in combination with lectin histochemistry. Rabbit antisera raised against ovine luteinizing hormone (LH)beta, proopiomelanocortin (POMC)-related peptides, and the growth hormone/prolactin family of tetrapod and fish species were used, and 25 kinds of lectins were tested. Three different types of adenohypophysial cells were revealed in the pituitary of brown hagfish. The first was stained with both anti-ovine LH beta and several D-mannose-binding lectins, such as Lens culinaris agglutinin and Pisum sativum agglutinin. This cell type predominated in the adenohypophysis in adults with developing gonads and thus appeared to be involved in the regulation of gonadal functions. The second was negative for anti-ovine LH beta but was stained with several N-acetylglucosamine-binding lectins, such as wheat germ agglutinin and Lycopersicon esculentum lectin. This cell type exhibited a weak positive reaction with anti-lamprey adrenocorticotropin (ACTH) and thus appeared to be related to POMC-like cells. The second cell type was found in the adenohypophysis regardless of the developmental state of the gonads. The third cell type was negative for both antisera and lectins. Since this cell type was numerous in juveniles and adults without developing gonads, most cells of this type were probably undifferentiated. These findings suggest that GTH and ACTH are major adenohypophysial hormones in the hagfish.
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Affiliation(s)
- Masumi Nozaki
- Sado Marine Biological Station, Faculty of Science, Niigata University, Tassha, Sado, Niigata, 952-2135, Japan.
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Miki M, Shimotani T, Uchida K, Hirano S, Nozaki M. Immunohistochemical detection of gonadotropin-like material in the pituitary of brown hagfish (Paramyxine atami) correlated with their gonadal functions and effect of estrogen treatment. Gen Comp Endocrinol 2006; 148:15-21. [PMID: 16574116 DOI: 10.1016/j.ygcen.2006.01.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2005] [Revised: 01/03/2006] [Accepted: 01/05/2006] [Indexed: 11/16/2022]
Abstract
Since hagfish are members of the most primitive group of living vertebrates, studies on their reproduction are indispensable for understanding phylogenetic aspects of vertebrate reproductive system. Nevertheless, our knowledge of the reproductive physiology of the hagfish, especially of the pituitary-gonadal axis, is almost completely lacking. In the present study, the relationship between the amount of immunoreactive gonadotropin (GTH)-like material in the pituitary gland and gonadal conditions was examined in the brown hagfish, Paramyxine atami. First, pituitary sections were stained immunohistochemically with anti-ovine LHbeta, and the degrees of the accumulation of GTH-like material were compared among three different groups of gonadal conditions; juveniles and adults with and without developing gonads. Immunoreactive GTH-like material was heavily accumulated in adults with developing gonads, whereas it was not or only weakly accumulated in juveniles or adults without developing gonads. Thus, there was a strong positive correlation between the amount of GTH-like material and gonadal conditions. Second, effect of estradiol benzoate on GTH-like material was examined using three groups of juvenile hagfish: initial control, sham control, and experimental animals. Experimental animals received estradiol benzoate resolved in sesame oil intraperitoneally every third day for 1 month, whereas sham control animals received the same doses of sesame oil. GTH-like material was heavily or moderately accumulated in most estrogen-treated animals, whereas it was not or weakly accumulated in initial or sham control animals. Thus, estrogen treatment in juvenile hagfish resulted in the large increase in the amount of GTH-like material. From these results, it is suggested the presence of not only GTH but also the hypophysial-gonadal feedback system in the hagfish.
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Affiliation(s)
- Makoto Miki
- Sado Marine Biological Station, Faculty of Science, Niigata University, Tassha, Sado, Niigata 952-2135, Japan
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Nozaki M, Oshima Y, Miki M, Shimotani T, Kawauchi H, Sower SA. Distribution of immunoreactive adenohypophysial cell types in the pituitaries of the Atlantic and the Pacific hagfish, Myxine glutinosa and Eptatretus burgeri. Gen Comp Endocrinol 2005; 143:142-50. [PMID: 16061072 DOI: 10.1016/j.ygcen.2005.03.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2004] [Revised: 03/01/2005] [Accepted: 03/07/2005] [Indexed: 10/25/2022]
Abstract
The hagfish is considered the most primitive vertebrate known, living or extinct. It remains an enigma whether adenohypophysial hormones similar to those of more advanced vertebrates are present in the hagfish pituitary gland or not. The present study aimed to detect immunoreactive adenohypophysial hormones in the hagfish pituitary gland, using antisera to tetrapod and fish adenohypophysial hormones as immunohistochemical probes. For this purpose, two species of hagfish, the Atlantic hagfish, Myxine glutinosa, and the Pacific hagfish, Eptatretus burgeri, were used. In both species, three different types of immunoreactive cells were detected in the adenohypophysis. (1) The first type of cells was gonadotropin (GTH)-like cells which were stained by antisera to LH-related GTHs, such as ovine LHbeta, human LHbeta, bullfrog LH, salmon LHbeta and sturgeon LHbeta in both species of hagfish. (2) The second type of cells that were detected was growth hormone (GH)/prolactin (PRL)-like cells. In M. glutinosa the cells were stained by antisera to salmon GH, salmon PRL, sturgeon GH, sturgeon PRL, blue shark GH, and lamprey GH. In E. burgeri the cells were only stained by anti-human GH and anti-sturgeon PRL. (3) The last type of cells was adrenocorticotropin (ACTH)-like cells. These cells were stained by antisera to lamprey ACTH and human beta-endorphin. In both species of hagfish, GTH-like cells were relatively abundant, and were distributed throughout the adenohypophysis, whereas GH/PRL-like and ACTH-like cells were few in number in the adenohypophysis. Based on these findings, we suggest that hagfish may have retained ancestral characteristics of key anterior pituitary hormones.
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Affiliation(s)
- Masumi Nozaki
- Sado Marine Biological Station, Niigata University, Tassha, Sado, Niigata 952-2135, Japan.
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