Characterization of skin and plasma type I antifreeze proteins from Atlantic (Liparis atlanticus) and dusky (Liparis gibbus) snailfish
Notice bibliographique
Résumé
Atlantic snailfish (Liparis atlanticus) and dusky snailfish (Liparis gibbus) belong to a large family of benthic and pelagic marine fishes that inhabit northern regions of the Atlantic Ocean. Both species spawn during the winter months in ice-laden inshore coastal regions around Newfoundland. Due to their harsh winter environment, snailfish are prime candidates for production of antifreeze proteins (AFPs). -- Initial results confirmed that plasma from both species contain alanine rich, α-helical, type I AFPs that are significantly larger (>9.3 kDa) than all previously described type I AFPs. Surprisingly, their skin tissues produce AFPs that are identical to those which circulate in blood. While all snailfish consistently express antifreeze mRNA in skin tissue, there is extreme individual variation in liver expression - an unusual phenomenon that has never been reported previously. Molecular analyses revealed that snailfish AFPs are products of multi gene families that consist of at least ten gene copies per genome. It is unclear if liver and skin antifreeze mRNAs are expressed by the same gene or a separate subset of genes which is typical of other fish that produce skin-type AFPs. -- Although the 113 residue snailfish AFPs are unusually long, their amino acid composition, highly a-helical secondary structure and the bipyramidal ice-crystals they create are characteristic of all type I AFPs. However, unlike other type I AFPs, snailfish proteins do not contain any obvious amino acid repeats or a continuous hydrophobic face that typify the structure of most other type I AFPs. These structural differences might have implications for their ice crystal binding properties. Biochemical experiments demonstrated that physiological concentrations of normal salts are responsible for a significant increase in thermal hysteresis activity in antifreeze proteins and glycoproteins. The colligative effects of these salts can account for the supplementary freezing point depression of blood required to ensure survival of marine fish in ice-laden seawater during winter. -- Two eDNA clones were identified from a snailfish liver eDNA library that code for fish eggshell proteins while a third one codes for a type II keratin. However, all three of these clones contain sections with substantial amino acid and nucleotide sequence \nsimilarity to snailfish type I AFPs. It is plausible that one or more of these proteins represent the ancestral proteins of snailfish type I AFPs. -- Novel type I AFPs were isolated and partially characterized from skin tissues of cunner (Tautogolabrus adspersus). Type II AFPs that are identical to those expressed in liver for export into blood were isolated from sea raven (Hemitripterus americanus) skin tissue extracts. Taken together the data generated in this thesis has strengthened and widened the scope of the hypothesis that skin represents the primordial source of AFP expression. It is clear that epithelial tissues are a primarily important source for antifreeze expression to enhance the complement of AFPs that protect fish from freezing in extreme cold environments. \n
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Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,001 | 0,000 |
| Bibliométrie | 0,000 | 0,001 |
| Études des sciences et des technologies | 0,001 | 0,001 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,001 | 0,000 |
| Intégrité de la recherche | 0,001 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».