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1.
T. T. Chen L. B. Agellon C. M. Lin H. J. Tsai Peijun Zhang L. I. González-Villasénor D. A. Powers 《Fish physiology and biochemistry》1989,7(1-6):381-385
The primary structures of two rainbow trout growth hormone mRNAs (GH1 and GH2) have been deduced by direct sequencing of their
respective cDNA clones and portions of the mRNA. Both GH1 and GH2 mRNA contain open reading frames comprised of 630 nucleotides
and encode 210 amino acid residues of which 11 are variant. The translated regions of both mRNA are flanked by a short but
rather conserved 5′-end, and a relatively long but highly diverged 3′-end. The differences at translated and 3′-untranslated
regions suggest that the GH1 and GH2 mRNA originate from different loci. The GH1 and GH2 mRNA are likely transcribed from
two distinct loci which were duplicated during tetraploidization of salmonid genome between 50 to 100 million years ago.
The GH2 gene has been isolated and sequenced from a rainbow trout genomic library. This gene spans a region of approximately
4 kilobases. The trout GH gene is comprised of 6 exons and 5 introns, in contrast to 5 exons and 4 introns in mammals. The
additional intron in the trout gene interrupts the translated regions that are analogous to the last exon of the mammalian
counterpart. The alleged internally repeating sequences in mammalian GH, prolactin (Pr1) and placental lactogen (PL) are not
observed in the predicted polypeptide sequence of trout GH. In addition, direct repeats that flank exons I, III and V of mammalian
GH, Pr1 and PL genes are absent in trout gene. These findings indicate that the rainbow trout GH gene structure does not support
the current hypothesis that internally repeated regions in GH, Pr1 and PL arose from a small primordial gene. 相似文献
2.
W. G. E. J. Schoonen J. G. D. Lambert M. T. Penders M. E. Van Roosmalen R. Van den Hurk H. J. Th. Goos P. G. W. J. Van Oordt 《Fish physiology and biochemistry》1989,6(2):61-78
Changes in ovarian steroidogenesis accompanying oocyte maturation and ovulation were studied in the African catfish,Clarias gariepinus. Laboratory-reared females with postvitellogenic ovaries were treated with pimozide and LHRH-analogue. The plasma gonadotropin levels were determined by means of a homologous radioimmunoassay, the condition of the ovaries was studied by histological examination of the follicles, and the steroidogenetic capacity of the ovaries was analyzed byin vitro incubation of tissue fragments for 3 h with [3H]-pregnenolone and [3H]androstenedione as precursors. Data were collected at regular intervals between 0 and 16 h after pimozide-LHRH analogue administration.Until 4 h after the beginning of the experiments the plasma gonadotropin levels did not rise above 25 ng/ml, the ovaries remained in the stage of postvitellogenesis, and testosterone was the main end product of steroidogenesis. Four hours later the gonadotropin concentration in the blood had risen to more than 150 ng/ml, and the ovaries had entered the stage of germinal vesicle migration. At the same time steroidogenesis shifted towards the production of 17,20-dihydroxy-4-pregnen-3-one, 5-pregnane-3, 17-diol-20-one, 5-pregnane-3,6,17-triol-20-one, 5-pregnane-3,17,20-triol and 5-pregnane-3,6,17,20-tetrol. During the subsequent stage of germinal vesicle breakdown the plasma gonadotropin level remained high, and the synthesis of the C21-steroids showed a further increase. Simultaneously, the production of some C19-steroid glucuronides was enhanced. The preovulation and especially the postovulation stages were accompanied by a gradual decrease in steroidogenic capacity of the ovaries, even though the plasma gonadotropin level remained high. It is concluded that the prematuration surge of gonadotropin influences the activity of enzymes involved in steroidogenesis, leading to a reduced C17,20-lyase and to an augmented activity of the enzymes 20-hydroxysteroid dehydrogenase (HSD), 5-reductase, 3-HSD, 6-hydroxylase and UDP-glucuronosyltransferase. During ovulation the activity of all steroidogenic enzymes, including such key enzymes as 3-HSD and 17-hydroxylase, gradually decreases.Not only 17,20-dihydroxy-4-pregnen-3-one, but also the 5-reduced pregnanes may be involved in inducing oocyte maturation and/or ovulation. The very polar triol and tetrol products may function, together with the steroid glucuronides as sex pheromones.A preliminary account of these results was presented at the XIII Conference of European Comparative Endocrinologists, Belgrade, September 7–12, 1986 相似文献
3.
P. H. M. Balm P. Pepels E. van Lieshout S. E. Wendelaar Bonga 《Fish physiology and biochemistry》1993,11(1-6):125-130
This study describes the effects of IL-1 (interleukin 1) and LPS (bacterial endotoxin lipopolysaccharide) on the release of
α-MSH (alpha melanocyte stimulating hormone) from the neurointermediate lobe (NIL) of the teleost Oreochromis mossambicus (tilapia). In vivo treatment of tilapia with IL-1 for 8 days led to a 49% inhibition of basal α-MSH release, measured by means of an in vitro micro-superfusion technique. The treatment did not affect the sensitivity of the tissue to TRH. In vitro, the release of α-MSH was inhibited by LPS in a dose dependent manner. In addition to its effects on the unstimulated release
of the hormone, LPS also blunted the response to a TRH stimulation. Together with recent results obtained by others demonstrating
the effects of (neuro-)peptides on immune parameters and the presence of cytokines in fish, the present data establish the
bidirectional character of the communication between the immune and the (neuro-)endocrine systems in teleosts.
Résumé Cette étude décrit les effets de l'IL-1 (interleukin 1) et du LPS (bacterial endotoxin lipopolysaccharide) sur la libération de α-MSH (alpha melanocyte stimulating hormone) par le lobe neurointermédiaire (NIL) d'un téléosteen Oreochromis mossambicus (tilapia). Le traitement in vivo du tilapia avec l'IL-1 pendent 8 jours conduit à une inhibition de 49% de la libération basale d'α-MSH mesurée à l'aide d'une technique in vitro de micro-superfusion. Ce traitement ne modifie pas la sensibilité du tissue au TRH. In vitro, la libération de α-MSH est inhibée par le LPS de manière dose-dépendante. En plus de ses effets sur la libération basale de α-MSH, le LPS bloque aussi la réponse à une stimulation par le TRH. Confrontés à des donnés récemment publiés montrant les effets de (neuro-)peptides sur les paramêtres immunitaires et la présence de cytokines chez les poissons, nos résultats établissent le caractère bidirectionnel de la communication entre le système immunitaire et les systèmes (neuro-)endocriniens.相似文献
4.
Plasma levels of L-thyroxine (T4) and 3,5,3-triiodo-L-thyronine (T3) and the percentage of plasma T4 and T3 present in the free (dialyzable) form (%FT4 and %FT3) were measured in 16 species (11 families) of tropical marine teleosts from an inshore Barbados reef. Mean plasma T4 varied from 0.2 ng/ml to 42 ng/ml; mean plasma T3 varied from < 0.2 ng/ml to 50 ng/ml. The highest T4 and T3 levels were recorded in parrot-fish and the lowest levels in filefish. The %oFT4 and %FT3 varied from 0.05–3.41%. Estimated levels of plasma free T4 and free T3 levels ranged from 0.4–466 pg/ml. The extremely wide inter- and intra-species ranges in levels of free T4 and T3 do not support a previous suggestion, based on temperate freshwater salmonid species, that free T4 and T3 levels in fish may fall within a relatively range narrow comparable to that of homeothermic vertebrates. 相似文献
5.
C. G. Coetzee 《African Zoology》2013,48(1):29-39
Certain aquatic Oligochaeta live successfully in organic-polluted waters while others cannot tolerate such conditions. Tubifex tempUtoni Southern and Llmnodrttus hoffmeisteri (Clap.), two non-gilled species, are compared to Branchiura sowerbyi (Beddard) and Dero nivea (Aiyer), two gilled species, concerning their haemoglobin concentration, the influence of low oxygen availability on the respiration rate and their reactions in an oxygen gradient. In contrast with L. hoffmeisteri and T. templetoni where a very narrow range of respiration dependency (pO2, 0-12 mm Hg) is found, B. sowerbyi and D. nivea have a level of respiratory dependence from pO2, 0-131 mm Hg. Haemoglobin concentrations are 6,238 - and 6,452 g/100 cm2 blood in L. hoffmeisteri and T. templetoni and 3,011 and 1,611 g/100 cm2 in B. sowerbyi and D. nivea respectively. In the oxygen gradient all four species have a preference for water with a high oxygen content. 相似文献
6.
Rosalind Murl Rolland 《Fish and Fisheries》2000,1(1):41-72
Evidence from the field and laboratory has shown that reproduction and early life-stage survival of several species of teleost fishes have been adversely affected following the release of several classes of synthetic, organic chemicals into the environment. Field studies from many geographic areas over several decades have found associations between exposure to synthetic chemicals in the environment and effects on hatchability, embryological success and larval survival. In more recent research, exposure to sewage treatment and bleached kraft mill effluents has been correlated with changes in reproductive system development and alterations in the endocrine physiology of wild teleost fishes. Loss of fecundity and damage during various stages of development and reproduction have been associated with exposure to endocrine disruptors, including many currently used chemicals. The supporting laboratory studies have confirmed that various wild fish species are sensitive to certain synthetic chemicals at levels of exposure of parts per billion and parts per trillion, concentrations that are biochemically, physiologically, and environmentally relevant. This paper reviews the relevant field and laboratory research, and organizes the studies using the ecoepidemiological criteria of time-order, strength of association, specificity, consistency on replication, coherence and predictive performance. There is sufficient evidence to conclude that ambient concentrations of synthetic chemicals in some regions are at or above concentrations at which certain species could be affected. The viability of fishery resources must be linked not only to the quantity of habitat but also to the quality of habitat. 相似文献
7.
鱼类高度不饱和脂肪酸合成的影响因素及其机理 总被引：1，自引：3，他引：1
由于海水鱼类的高度不饱和脂肪酸(HUFA)合成能力一般缺乏或很弱,所以其配合饲料中需要添加较高比例富含HUFA的鱼油才能满足其正常生理功能的需要。随着鱼油资源的日益紧缺,研究者们试图寻找提高鱼体内源性HUFA合成能力的方法或途径,以提高配合饲料中植物油替代鱼油的比例,而HUFA合成调控机制的阐明将有助于达到此目的。本文着重介绍影响鱼类HUFA生物合成的主要因素及其作用机理,包括不同脂肪源、日粮中n-3/n-6多不饱和脂肪酸(PUFA)比例、维生素和矿物质等营养因子,温度、盐度、光周期等环境因子,以及转录因子、激素与遗传因子等,以期为鱼类HUFA合成调控机制的深入研究提供参考。 相似文献
8.
Three experimental approaches were chosen to study the question if the progestin 17-hydroxy-20-dihydroprogesterone (1720OHP) is synthesised in testes of young Oncorhynchus mykiss, in which the absence of spermatozoa was verified histologically: first, in order to detect 20-hydroxysteroid dehydrogenase activity (20HSD), testes homogenates were incubated with 3H-labeled 17OHP.Metabolites were analysed by TLC, HPLC, and repeated crystallization to constant isotope ratios. One of the metabolites was identified as 1720OHP-3H, indicating that already immature testes contain 20HSD activity and are able to produce 20-reduced steroids. Second, 1720OHP was quantified by radioimmunoassay in incubates of testes fragments. The sensitivity of the gonads to gonadotropin II (GtH II) became evident when comparing incubations in the absence and presence of GtH II. Third, plasma levels of 1720OHP were significantly higher in animals injected with partially purified salmon gonadotropin, compared to controls. Thus, for the first time, it could be shown that 20HSD is present in testicular cells other than spermatozoa. Furthermore, 1720OHP is indeed secreted at a very early stage of testicular development; 1720OHP secretion is also responsive to GtH II. Future studies will have to show if the functions of this progestin include the stimulation of spermatogenesis. 相似文献
9.
Immune responses of teleost fish 总被引：6，自引：0，他引：6
In fish all the pre-requisites to mount a specific immune response are present, but the main differences from the mammalian system are that the secondary response is relatively minor and IgG is not present. In teleosts mainly IgM is present, and IgD has been recently described but its function is, as yet, unknown. However, different forms of fish IgM and its observed flexibility of structure may compensate for a lack of Ig class diversity. The innate immune response of teleosts is highly developed. Multiple forms of key constitutive and inducible components, such as lysozyme, C3, alpha2-macroglobulin and C-reactive protein, are present, and may enhance immune recognition. Low ambient temperature appears to have an impact on all aspects of the immune response, particularly the T-dependent specific immune response due to the non-adaptive lipid composition of T-cell membranes. Temperature effects on the nonspecific immune system are less well characterised, but there is evidence that low temperatures are also suppressive. Knowledge of immune system function becomes essential for disease prevention strategies such as the development of vaccines, selection for increased disease resistance and identification of genes suitable for trangenesis. 相似文献
10.
Mihly KLMN David L. L&#x;RINCZ Olivr M. SEB&#x;K Csilla ARI Erzsbet OSZWALD Hiroaki SOMIYA Veronika JANCSIK 《Integrative zoology》2020,15(1):16-31
The aim of the present paper was to check for the presence of cerebrovascular dystroglycan in vertebrates, because dystroglycan, which is localized in the vascular astroglial end‐feet, has a pivotal function in glio‐vascular connections. In mammalian brains, the immunoreactivity of β‐dystroglycan subunit delineates the vessels. The results of the present study demonstrate similar patterns in other vertebrates, except for anurans and the teleost groups Ostariophysi and Euteleostei. In this study, we investigated 1 or 2 representative species of the main groups of Chondrichthyes, teleost and non‐teleost ray‐finned fishes, urodeles, anurans, and reptiles. We also investigated 5 mammalian and 3 bird species. Animals were obtained from breeders or fishermen. The presence of β‐dystroglycan was investigated immunohistochemically in free‐floating sections. Pre‐embedding electron microscopical immunohistochemistry on Heterodontus japonicus shark brains demonstrated that in Elasmobranchii, β‐dystroglycan is also localized in the perivascular glial end‐feet despite the different construction of their blood–brain barrier. The results indicated that the cerebrovascular β‐dystroglycan immunoreactivity disappeared separately in anurans, and in teleosts, in the latter group before its division to Ostariophysi and Euteleostei. Immunohistochemistry in muscles and western blots from brain homogenates, however, detected the presence of β‐dystroglycan, even in anurans and all teleosts. A possible explanation is that in the glial end‐feet, β‐dystroglycan is masked in these animals, or disappeared during adaptation to the freshwater habitat. 相似文献