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Graham LA, Davies PL. Fish antifreeze protein origin in sculpins by frameshifting within a duplicated housekeeping gene. FEBS J 2024. [PMID: 38923815 DOI: 10.1111/febs.17205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 03/25/2024] [Accepted: 06/07/2024] [Indexed: 06/28/2024]
Abstract
Antifreeze proteins (AFPs) are found in a variety of marine cold-water fishes where they prevent freezing by binding to nascent ice crystals. Their diversity (types I, II, III and antifreeze glycoproteins), as well as their scattered taxonomic distribution hint at their complex evolutionary history. In particular, type I AFPs appear to have arisen in response to the Late Cenozoic Ice Age that began ~ 34 million years ago via convergence in four different groups of fish that diverged from lineages lacking this AFP. The progenitor of the alanine-rich α-helical type I AFPs of sculpins has now been identified as lunapark, an integral membrane protein of the endoplasmic reticulum. Following gene duplication and loss of all but three of the 15 exons, the final exon, which encoded a glutamate- and glutamine-rich segment, was converted to an alanine-rich sequence by a combination of frameshifting and mutation. Subsequent gene duplications produced numerous isoforms falling into four distinct groups. The origin of the flounder type I AFP is quite different. Here, a small segment from the original antiviral protein gene was amplified and the rest of the coding sequence was lost, while the gene structure was largely retained. The independent origins of type I AFPs with up to 83% sequence identity in flounder and sculpin demonstrate strong convergent selection at the level of protein sequence for alanine-rich single alpha helices that bind to ice. Recent acquisition of these AFPs has allowed sculpins to occupy icy seawater niches with reduced competition and predation from other teleost species.
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Affiliation(s)
- Laurie A Graham
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Canada
| | - Peter L Davies
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Canada
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Campinho MA. Teleost Metamorphosis: The Role of Thyroid Hormone. Front Endocrinol (Lausanne) 2019; 10:383. [PMID: 31258515 PMCID: PMC6587363 DOI: 10.3389/fendo.2019.00383] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Accepted: 05/28/2019] [Indexed: 02/06/2023] Open
Abstract
In most teleosts, metamorphosis encompasses a dramatic post-natal developmental process where the free-swimming larvae undergo a series of morphological, cellular and physiological changes that enable the larvae to become a fully formed, albeit sexually immature, juvenile fish. In all teleosts studied to date thyroid hormones (TH) drive metamorphosis, being the necessary and sufficient factors behind this developmental transition. During metamorphosis, negative regulation of thyrotropin by thyroxine (T4) is relaxed allowing higher whole-body levels of T4 that enable specific responses at the tissue/cellular level. Higher local thyroid cellular signaling leads to cell-specific responses that bring about localized developmental events. TH orchestrate in a spatial-temporal manner all local developmental changes so that in the end a fully functional organism arises. In bilateral teleost species, the most evident metamorphic morphological change underlies a transition to a more streamlined body. In the pleuronectiform lineage (flatfishes), these metamorphic morphological changes are more dramatic. The most evident is the migration of one eye to the opposite side of the head and the symmetric pelagic larva development into an asymmetric benthic juvenile. This transition encompasses a dramatic loss of the embryonic derived dorsal-ventral and left-right axis. The embryonic dorsal-ventral axis becomes the left-right axis, whereas the embryonic left-right axis becomes, irrespectively, the dorsal-ventral axis of the juvenile animal. This event is an unparalleled morphological change in vertebrate development and a remarkable display of the capacity of TH-signaling in shaping adaptation and evolution in teleosts. Notwithstanding all this knowledge, there are still fundamental questions in teleost metamorphosis left unanswered: how the central regulation of metamorphosis is achieved and the neuroendocrine network involved is unclear; the detailed cellular and molecular events that give rise to the developmental processes occurring during teleost metamorphosis are still mostly unknown. Also in flatfish, comparatively little is still known about the developmental processes behind asymmetric development. This review summarizes the current knowledge on teleost metamorphosis and explores the gaps that still need to be challenged.
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Abstract
Antifreeze proteins (AFPs) protect marine fishes from freezing in icy seawater. They evolved relatively recently, most likely in response to the formation of sea ice and Cenozoic glaciations that occurred less than 50 million years ago, following a greenhouse Earth event. Based on their diversity, AFPs have independently evolved on many occasions to serve the same function, with some remarkable examples of convergent evolution at the structural level, and even instances of lateral gene transfer. For some AFPs, the progenitor gene is recognizable. The intense selection pressure exerted by icy seawater, which can rapidly kill unprotected fish, has led to massive AFP gene amplification, as well as some partial gene duplications that have increased the size and activity of the antifreeze. The many protein evolutionary processes described in Gordon H. Dixon's Essays in Biochemistry article will be illustrated here by examples from studies on AFPs. Abbreviations: AFGP: antifreeze glycoproteins; AFP: antifreeze proteins; GHD: Gordon H. Dixon; SAS: sialic acid synthase; TH: thermal hysteresis.
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Affiliation(s)
- Peter L Davies
- a Department of Biomedical and Molecular Sciences , Queen's University , Kingston , Canada
| | - Laurie A Graham
- a Department of Biomedical and Molecular Sciences , Queen's University , Kingston , Canada
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Alves RN, Sundell KS, Anjos L, Sundh H, Harboe T, Norberg B, Power DM. Structural and functional maturation of skin during metamorphosis in the Atlantic halibut (Hippoglossus hippoglossus). Cell Tissue Res 2018; 372:469-492. [PMID: 29464365 DOI: 10.1007/s00441-018-2794-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Accepted: 01/15/2018] [Indexed: 11/29/2022]
Abstract
To establish if the developmental changes in the primary barrier and osmoregulatory capacity of Atlantic halibut skin are modified during metamorphosis, histological, histochemical, gene expression and electrophysiological measurements were made. The morphology of the ocular and abocular skin started to diverge during the metamorphic climax and ocular skin appeared thicker and more stratified. Neutral mucins were the main glycoproteins produced by the goblet cells in skin during metamorphosis. Moreover, the number of goblet cells producing neutral mucins increased during metamorphosis and asymmetry in their abundance was observed between ocular and abocular skin. The increase in goblet cell number and their asymmetric abundance in skin was concomitant with the period that thyroid hormones (THs) increase and suggests that they may be under the control of these hormones. Several mucin transcripts were identified in metamorphosing halibut transcriptomes and Muc18 and Muc5AC were characteristic of the body skin. Na+, K+-ATPase positive (NKA) cells were observed in skin of all metamorphic stages but their number significantly decreased with the onset of metamorphosis. No asymmetry was observed between ocular and abocular skin in NKA cells. The morphological changes observed were linked to modified skin barrier function as revealed by modifications in its electrophysiological properties. However, the maturation of the skin functional characteristics preceded structural maturation and occurred at stage 8 prior to the metamorphic climax. Treatment of Atlantic halibut with the THs disrupter methimazole (MMI) affected the number of goblet cells producing neutral mucins and the NKA cells. The present study reveals that the asymmetric development of the skin in Atlantic halibut is TH sensitive and is associated with metamorphosis and that this barrier's functional properties mature earlier and are independent of metamorphosis.
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Affiliation(s)
- Ricardo N Alves
- Comparative Endocrinology and Integrative Biology Group (CEIB), CCMAR, CIMAR Laboratório Associado, University of Algarve, Campus de Gambelas, 8005-139, Faro, Portugal.,King Abdullah University of Science and Technology (KAUST), Red Sea Research Center (RSRC), Thuwal, 23955-6900, Kingdom of Saudi Arabia
| | - Kristina S Sundell
- Fish Endocrinology Laboratory, Department of Biological and Environmental Sciences, University of Gothenburg, Box 463, SE-405 30, Gothenburg, Sweden
| | - Liliana Anjos
- Comparative Endocrinology and Integrative Biology Group (CEIB), CCMAR, CIMAR Laboratório Associado, University of Algarve, Campus de Gambelas, 8005-139, Faro, Portugal
| | - Henrik Sundh
- Fish Endocrinology Laboratory, Department of Biological and Environmental Sciences, University of Gothenburg, Box 463, SE-405 30, Gothenburg, Sweden
| | - Torstein Harboe
- Institute of Marine Research, Austevoll Research Station, 5392, Storebø, Norway
| | - Birgitta Norberg
- Institute of Marine Research, Austevoll Research Station, 5392, Storebø, Norway
| | - Deborah M Power
- Comparative Endocrinology and Integrative Biology Group (CEIB), CCMAR, CIMAR Laboratório Associado, University of Algarve, Campus de Gambelas, 8005-139, Faro, Portugal.
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Epithelial dominant expression of antifreeze proteins in cunner suggests recent entry into a high freeze-risk ecozone. Comp Biochem Physiol A Mol Integr Physiol 2012; 164:111-8. [PMID: 23085291 DOI: 10.1016/j.cbpa.2012.10.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Revised: 10/12/2012] [Accepted: 10/15/2012] [Indexed: 11/23/2022]
Abstract
Most marine teleost fishes residing in a high freeze-risk ecozone, such as the coastal waters of Newfoundland during winter, avoid freezing by secreting high concentrations of antifreeze proteins (AFP) into their blood plasma where they can bind to and prevent the growth of ice that enter the fish. Cunner (Tautogolabrus adspersus), which overwinter in such shallow waters are the only known exception. Although this species does produce type I AFP, the plasma levels are too low to be of value as a freeze protectant. Southern and Northern blot analyses carried out in this study establish that the cunner AFP genes belong to a multigene family that is predominantly expressed in external epithelia (skin and gill filaments). These results support the hypothesis that the survival of cunner in icy waters is attributable in part to epithelial AFP that help block ice propagation into their interior milieu. In contrast to the cunner, heterospecifics occupying the same habitat have greater freeze protection because they produce AFP in the liver for export to the plasma as well as in external epithelia. Since the external epithelia would be the first tissue to come into contact with ice it is possible that one of the earliest steps involved in the evolution of freeze resistant fish could have been the expression of AFP in tissues such as the skin. We suggest that this epithelial-dominant AFP expression represents a primitive stage in AFP evolution and propose that cunner began to inhabit "freeze-risk ecozones" more recently than heterospecifics.
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Hobbs RS, Shears MA, Graham LA, Davies PL, Fletcher GL. Isolation and characterization of type I antifreeze proteins from cunner, Tautogolabrus adspersus, order Perciformes. FEBS J 2011; 278:3699-710. [DOI: 10.1111/j.1742-4658.2011.08288.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Padrós F, Villalta M, Gisbert E, Estévez A. Morphological and histological study of larval development of the Senegal sole Solea senegalensis: an integrative study. JOURNAL OF FISH BIOLOGY 2011; 79:3-32. [PMID: 21722108 DOI: 10.1111/j.1095-8649.2011.02942.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
This study provides a comprehensive description of the main morphological and histological events that take place during larval and post-larval development of Senegal sole Solea senegalensis in order to establish a reference for its normal developmental organogenesis. Five stages have been described. Before gill development at the onset of metamorphosis (eye migration process, stage 4c), the skin was the main site of gas and ion exchange, whereas during stages 3 and 4, the skin begins differentiating into the definitive juvenile structure. The timing of development of the endocrine system depends on each organ, the endocrine pancreas and thyroid gland being the first to differentiate (stages 2 and 3, respectively), followed by the interrenal tissue and stannius corpuscles that develop at metamorphosis (stages 4 and 4c, respectively). The differentiation and maturation of the lymphohaematopoietic organs was coupled with the increase in complexity of the cardiovascular system and the presence of mature erythrocytes (stage 4b), which might be attributed to the change in respiration and the development of fully functional gills. In the differentiation of sensory structures, the development of eyes, inner ear, neuromasts and olfactory organs was rapid, with most of these organs becoming fully developed soon after hatching (stage 1). Vision, chemo- and mechano-reception developed very early in ontogeny, in parallel with the development of the central nervous system and changes in feeding habits. Although the general pattern of development in S. senegalensis appeared similar to most marine fish larvae already described, there were species-specific ontogenetic characteristics probably derived from the species' particular environment (subtropical waters) and behaviour (nocturnal, benthic, omnivorous feeding habits). These results on the organogenesis of larvae are a useful tool for establishing the functional systemic capabilities and physiological requirements of larvae to ensure optimal welfare and growth under aquaculture conditions.
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Affiliation(s)
- F Padrós
- Fish Diseases Diagnostic Service, Veterinary School, Departament de Biologia Animal, Biologia Vegetal i Ecologia, Universitat Autònoma de Barcelona, 08190 Bellaterra (Cerdanyola del Vallès), Spain.
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Martínez-Páramo S, Pérez-Cerezales S, Robles V, Anel L, Herráez MP. Incorporation of antifreeze proteins into zebrafish embryos by a non-invasive method. Cryobiology 2008; 56:216-22. [PMID: 18457823 DOI: 10.1016/j.cryobiol.2008.03.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2007] [Revised: 01/30/2008] [Accepted: 03/20/2008] [Indexed: 11/16/2022]
Abstract
The cryopreservation of fish embryos is a challenge because of their structure, with multiple compartments and permeability barriers, and their high chilling sensitivity. Vitrification at advanced developmental stages is considered to be the more promising option. Nevertheless, all reported attempts have failed. Previous studies demonstrated a better ability for freezing in species that naturally express antifreeze proteins (AFPs). These proteins have been delivered into other fish embryos using time-consuming techniques like microinjection. In the present study, the introduction of FITC labelled AFPs was assayed in zebrafish embryos at early developmental stages (from 2-cell to high blastula stage), before the formation of the yolk syncytial layer, by an easy and non-invasive method and evaluated by fluorescence and confocal microscopy. Incubation with AFPs at 128-cell or high blastula stage provides incorporation of the protein in 50-90% of embryos without affecting hatching. Incubation in media containing protein is a simple, harmless and effective method which makes it possible to treat several embryos at the same time. AFPs remain located in derivatives from marginal blastomeres: the yolk syncytial layer, the most cryosensitive and impermeable barrier, and different digestive organs. Our findings demonstrate that delivery of AFP type I and AFP type III into zebrafish embryos by incubation in media containing protein is a simple and harmless method that may improve cryoprotection of the cellular compartment.
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Affiliation(s)
- S Martínez-Páramo
- Department of Molecular Biology, Area of Cell Biology, University of León, Campus de Vegazana 24071, León, Spain
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Graham LA, Marshall CB, Lin FH, Campbell RL, Davies PL. Hyperactive antifreeze protein from fish contains multiple ice-binding sites. Biochemistry 2008; 47:2051-63. [PMID: 18225917 DOI: 10.1021/bi7020316] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Antifreeze proteins (AFPs) are produced to prevent freezing in many fish species that are exposed to icy seawater. There are a number of nonhomologous types of AFPs, diverse in both sequence and structure, which share the function of binding to ice and inhibiting its growth. We recently discovered a hyperactive AFP in the winter flounder and related species that is many-fold more active than other fish AFPs. Like the 3-4-kDa type I AFPs, it is alanine-rich and highly helical, but this 17-kDa protein is considerably larger and forms a dimer. We have sequenced the cDNA encoding this new AFP to gain insight into its structure and evolutionary relationship to the type I AFP family. The gene is clearly homologous to the righteye flounder type I AFP genes. Thus we have designated this protein "hyperactive type I AFP" (hyp-type I). The sequence of hyp-type I AFP supports a structural model in which two extended 195-amino acid alpha-helices form an amphipathic homodimer with a series of linked Ala- and Thr-rich patches on the surface of the dimer, each of which resembles ice-binding sites of type I AFPs. The superior activity of hyp-type I AFP may derive from the large combined surface area of the ice-binding sites, recognition of multiple planes of ice, and protection of the basal plane from ice growth.
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Affiliation(s)
- Laurie A Graham
- Department of Biochemistry and Protein Function Discovery Group, Queen's University, Kingston, Ontario, Canada K7L 3N6
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Evans RP, Hobbs RS, Goddard SV, Fletcher GL. The importance of dissolved salts to the in vivo efficacy of antifreeze proteins. Comp Biochem Physiol A Mol Integr Physiol 2007; 148:556-61. [PMID: 17707669 DOI: 10.1016/j.cbpa.2007.07.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2007] [Revised: 07/16/2007] [Accepted: 07/17/2007] [Indexed: 10/23/2022]
Abstract
Antifreeze proteins (AFP) and antifreeze glycoproteins (AFGP) lower the freezing point of marine fish plasma non-colligatively by specifically adsorbing to certain surfaces of ice crystals, modifying their structure and inhibiting further growth. While the freezing point is lowered, the melting point is unaltered and the difference between the two is termed thermal hysteresis (TH). In pure water, the level of TH is directly related to the intrinsic activity of the specific AF(G)P in solution and to their concentration. Results of this study indicate that when AF(G)P are dissolved in salt solutions, such as NaCl, encompassing the range they could encounter in nature, there is a synergistic enhancement of basal TH that is positively related to the salt concentration. This enhancement is likely a result of the hydration shell surrounding the dissolved ions and, as a consequence, reducing freezable water. A secondary reason for the enhancement is that the salt could be influencing the hydration shell surrounding the AF(G)P, increasing their solubility and thus the protein surface area available to adsorb to the ice/water interface. The former hypothesis for the salt enhanced TH has implications for the in vivo function of AF(G)P, particularly at the seawater/external epithelia (gills, skin, stomach) interface. The latter hypothesis is likely only relevant to in vitro situations where freeze dried protein is dissolved in low salt solutions.
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Affiliation(s)
- Robert P Evans
- Ocean Sciences Centre, Memorial University of Newfoundland, St John's Newfoundland, Canada A1C 5S7
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Campinho MA, Silva N, Sweeney GE, Power DM. Molecular, cellular and histological changes in skin from a larval to an adult phenotype during bony fish metamorphosis. Cell Tissue Res 2006; 327:267-84. [PMID: 17028894 DOI: 10.1007/s00441-006-0262-9] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2006] [Accepted: 05/31/2006] [Indexed: 12/12/2022]
Abstract
Developmental models for skin exist in terrestrial and amphibious vertebrates but there is a lack of information in aquatic vertebrates. We have analysed skin epidermal development of a bony fish (teleost), the most successful group of extant vertebrates. A specific epidermal type I keratin cDNA (hhKer1), which may be a bony-fish-specific adaptation associated with the divergence of skin development (scale formation) compared with other vertebrates, has been cloned and characterized. The expression of hhKer1 and collagen 1alpha1 in skin taken together with the presence or absence of keratin bundle-like structures have made it possible to distinguish between larval and adult epidermal cells during skin development. The use of a flatfish with a well-defined larval to juvenile transition as a model of skin development has revealed that epidermal larval basal cells differentiate directly to epidermal adult basal cells at the climax of metamorphosis. Moreover, hhKer1 expression is downregulated at the climax of metamorphosis and is inversely correlated with increasing thyroxin levels. We suggest that, whereas early mechanisms of skin development between aquatic and terrestrial vertebrates are conserved, later mechanisms diverge.
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Affiliation(s)
- Marco A Campinho
- Comparative Molecular Endocrinology Group, Marine Science Centre, Universidade do Algarve, 8005-139, Faro, Portugal
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12
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Robles V, Cabrita E, Fletcher GL, Shears MA, King MJ, Herráez MP. Vitrification assays with embryos from a cold tolerant sub-arctic fish species. Theriogenology 2005; 64:1633-46. [PMID: 15951012 DOI: 10.1016/j.theriogenology.2005.04.014] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2005] [Revised: 03/18/2005] [Accepted: 04/03/2005] [Indexed: 11/19/2022]
Abstract
Pseudopleuronectes americanus is a Northern teleost species that produces antifreeze proteins (AFPs) to protect them from freezing during the winter. These AFPs bind to ice crystals to inhibit their growth, and they also protect cell membranes at low temperatures. In this study, vitrification trials were done with fish embryos at three different developmental stages, using two different protocols for incorporating the vitrifying solutions. Toxicity of the cryoprotectants and permeability to dimethyl sulfoxide were analyzed. Embryos were vitrified in 0.5 ml straws by direct immersion in liquid nitrogen, and their morphology and development analyzed following thaw. The embryos responded well to vitrification as evidenced by the high percentage that exhibited good morphology following thaw. Although none of the embryos hatched, a small percentage (0.92%) of them showed active movements within the chorion and continued to develop for a number of days following thaw. This is the first record of post-thaw development of vitrified fish embryos.
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Affiliation(s)
- V Robles
- Center for Marine Sciences, Campus de Gambelas, University of Algarve, Faro 8005-139, Portugal.
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Evans RP, Fletcher GL. Type I antifreeze proteins expressed in snailfish skin are identical to their plasma counterparts. FEBS J 2005; 272:5327-36. [PMID: 16218962 DOI: 10.1111/j.1742-4658.2005.04929.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Type I antifreeze proteins (AFPs) are usually small, Ala-rich alpha-helical polypeptides found in right-eyed flounders and certain species of sculpin. These proteins are divided into two distinct subclasses, liver type and skin type, which are encoded by separate gene families. Blood plasma from Atlantic (Liparis atlanticus) and dusky (Liparis gibbus) snailfish contain type I AFPs that are significantly larger than all previously described type I AFPs. In this study, full-length cDNA clones that encode snailfish type I AFPs expressed in skin tissues were generated using a combination of library screening and PCR-based methods. The skin clones, which lack both signal and pro-sequences, produce proteins that are identical to circulating plasma AFPs. Although all fish examined consistently express antifreeze mRNA in skin tissue, there is extreme individual variation in liver expression - an unusual phenomenon that has never been reported previously. Furthermore, genomic Southern blot analysis revealed that snailfish AFPs are products of multigene families that consist of up to 10 gene copies per genome. The 113-residue snailfish AFPs do not contain any obvious amino acid repeats or continuous hydrophobic face which typify the structure of most other type I AFPs. These structural differences might have implications for their ice-crystal binding properties. These results are the first to demonstrate a dual liver/skin role of identical type I AFP expression which may represent an evolutionary intermediate prior to divergence into distinct gene families.
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Affiliation(s)
- Robert P Evans
- Ocean Sciences Centre, Memorial University of Newfoundland, St. John's, Newfoundland, Canada.
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Gauthier SY, Marshall CB, Fletcher GL, Davies PL. Hyperactive antifreeze protein in flounder species. The sole freeze protectant in American plaice. FEBS J 2005; 272:4439-49. [PMID: 16128813 DOI: 10.1111/j.1742-4658.2005.04859.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The recent discovery of a large hyperactive antifreeze protein in the blood plasma of winter flounder has helped explain why this fish does not freeze in icy seawater. The previously known, smaller and much less active type I antifreeze proteins cannot by themselves protect the flounder down to the freezing point of seawater. The relationship between the large and small antifreezes has yet to be established, but they do share alanine-richness (> 60%) and extensive alpha-helicity. Here we have examined two other righteye flounder species for the presence of the hyperactive antifreeze, which may have escaped prior detection because of its lability. Such a protein is indeed present in the yellowtail flounder judging by its size, amino acid composition and N-terminal sequence, along with the previously characterized type I antifreeze proteins. An ortholog is also present in American plaice based on the above criteria and its high specific antifreeze activity. This protein was purified and shown to be almost fully alpha-helical, highly asymmetrical, and susceptible to denaturation at room temperature. It is the only detectable antifreeze protein in the blood plasma of the American plaice. Because this species appears to lack the smaller type I antifreeze proteins, the latter may have evolved by descent from the larger antifreeze.
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Affiliation(s)
- Sherry Y Gauthier
- Department of Biochemistry, Queen's University, Kingston, ON, Canada
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