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1.
K. Ura S. Mizuno T. Okubo Y. Chida N. Misaka S. Adachi K. Yamauchi 《Fish physiology and biochemistry》1997,17(1-6):397-403
Changes in immunoreactivity of Na+/K+-ATPase -subunit in gill sections of wild masu salmon (Oncorhynchus masou) during the parr-smolt transformation (smoltification) were compared with changes in gill Na+/K+-ATPase specific activity. Gill Na+/K+-ATPase specific activity increased from April and peaked in May. Immunohistochemical analysis, using an antiserum against a synthetic oligopeptide based on the conserved region of the Na+/K+-ATPase -subunit, revealed that immunoreactivity was confined to chloride cells in the surface layer of primary lamellae and the proximal end of secondary lamellae. The size and number of these cells increased gradually from February to May; however, the number of chloride cells of the secondary lamellae decreased in May. These data suggest that the synthesis of Na+/K+-ATPase and the proliferation of chloride cells occur prior to the elevation of enzyme activity. Moreover, it is likely the proliferation and hypertrophy of chloride cells on primary lamellae prepare smolts for entry into seawater and migration in the ocean. 相似文献
2.
放养规格对银化期大西洋鲑生长的影响及生理响应机理 总被引：1，自引：1，他引：0
内分泌系统在调节大西洋鲑(Salmo salar L.)的银化过程中,除了要尽快建立更高效的渗透调节机制外,鱼体自身的生理反应变化还要更好地适应降海后的生活。试验研究了平均体质量(30.25±2.12)g(SW1)、(24.27±1.59)g(SW2)和(18.05±2.46)g(SW3)大西洋鲑,1~42 d光照周期为12L:12D;43~84 d为全光照下(24L:0D)的生长及生理响应机理。试验结果表明,SW2组大西洋鲑的肥满度、日增质量、饲料转化率、净增质量最高,与其他组差异显著(P0.05)。SW2组体质量、体长特定生长率均显著高于其他处理组(P0.05),各组间体质量、体长变异系数差异显著(P0.05)。试验前6周不同处理组大西洋鲑体长变异系数差异不显著(P0.05)。后6周全光照时,SW1、SW2组体长变异系数显著增加,且SW1组显著高于其他组(P0.05)。SW3组的大西洋鲑体质量变异系数变化较大。前6周光照期为12L:12D时,SW1、SW2两组体质量变异系数差异不显著(P0.05),后6周改为全光照时,3个处理组间体质量变异系数差异减小。但在84 d时,SW3组体质量变异系数显著高于其他组(P0.05)。随着养殖规格的增大,血红蛋白浓度升高,红细胞数目增加,说明鱼体需氧量增加。SW3组白细胞数目、淋巴细胞数目和中性粒细胞数目最高,表明鱼体抗病能力强。红细胞数目在SW1和SW2组间无显著差异(P0.05),但均显著高于SW3组(P0.05)。血栓细胞数目随着放养规格的增加而下降,且在3个规格组之间差异显著(P0.05)。中性粒细胞数目在3个规格组之间并没有显著性差异(P0.05)。SW2组总蛋白、白蛋白含量最高,且各组间差异显著(P0.05)。总胆固醇、甘油三酯浓度随鱼体规格增大而增加(P0.05),表明大西洋鲑血液和体内对能量的利用增强。SW2组代谢产物尿酸、尿素浓度最高,且SW1、SW2组的浓度值均显著高于SW3组(P0.05)。SW3组大西洋鲑血清中总胆红素显著高于其他两组(P0.05)。各组间大西洋鲑血清中葡萄糖浓度没有显著性差异(P0.05)。SW3组肌酸激酶浓度最高,但各组间没有显著性差异(P0.05)。该研究结果建议选择体质量(24.27±1.59)g的大西洋鲑开始银化,利于优化养殖条件、以较低成本增加单位水体养殖产量和苗种规模化生产。 相似文献
3.
Whole animal transepithelial potentials (TEP) of yearling coho salmon (Oncorhynchus kisutch) in fresh water and after transfer to seawater were recorded throughout parr-smolt transformation (smoltification) from February to August 1984, along with plasma Na+ and Cl– concentrations and osmolality. Based on plasma ion regulation in seawater, the yearling coho in this study completed smoltification and attained sea-water adaptability in April. TEP in freshwater fish decreased (became inside-negative) after smoltification, and the TEP increased significantly (P < 0.01) after seawater transfer. When fish were transferred into seawater, thyroxine increased TEP of the transferred smolts by approximately 30% over the control level (P < 0.01) in April, but this did not occur when freshwater postsmolts were transferred in July and August. Hypophysectomy increased TEP (P < 0.01) in fresh water; it did not affect the TEP of the fish after seawater transfer. Ovine prolactin (3 g/g body weight) implanted into seawater-adapted fish caused a reduction in TEP (P < 0.01) when fish were exposed to fresh water. Whole-animal TEP appears to provide a valuable index of the completion of smoltification (April–May) and a useful tool for investigating the endocrine control of salmonid osmoregulation. 相似文献
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The Atlantic salmon (Salmo salar) has a life cycle that involves inhabiting both fresh and salt water. The control and maintenance of ionic balance is under control of the endocrine system. Prolactin is reportedly an important hormone for the ionic balance of salts in the body fluids of fish, especially during the periods of time spent in fresh water. An Atlantic salmon pituitary cDNA library was constructed in gt 11, from which a full length Atlantic salmon prolactin cDNA was isolated using a chinook salmon (Oncorhynchus tshawytscha) prolactin cDNA probe. The sequence of this clone (ATPRL-5) was determined. Comparison of this sequence and other published sequences showed all the prolactin genes isolated to date are highly conserved. The expression of the prolactin mRNA from adult and juvenile salmon was studied after transfer between salinities. Expression varied in the predicted manner. Adult salmon transferred to fresh water showed large increases in the prolactin mRNA level compared to control fish (>600% increase after 72 h). Only a small difference was observed when smolts (juvenile salmon) were transferred to salt water. 相似文献
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Heather A. Stewart Karen M. Cogliati Eric J. Billman Rob Chitwood Julia R. Unrein David L. G. Noakes 《Journal Of Applied Aquaculture》2017,29(3-4):277-290
Seasonal timing of transportation and acclimation of juvenile Chinook salmon (Oncorhynchus tshawytscha) between hatcheries may affect osmoregulation and survival. We investigated the duration of time fish need to acclimate to hatchery conditions prior to being presented with a saltwater challenge. We monitored acute survival and osmoregulatory ability following a 24-h saltwater challenge of fish previously transported to a hatchery at various times throughout the year compared to fish reared at that hatchery. Fish that underwent a saltwater challenge 3 weeks after transport had significantly reduced osmoregulatory performance and increased mortality compared to fish allowed an acclimation period of 2 months. 相似文献
8.
Ingvill Jensen Mathias C. Overrein Brge N. Fredriksen Guro Strandskog Tore Seternes 《Journal of fish diseases》2019,42(9):1271-1282
In today's aquaculture of Atlantic salmon (Salmo salar L.), a majority of viral disease outbreaks occur after seawater transfer. A relevant question is how the parr–smolt transformation influences the efficacy of viral vaccines and the innate resistance against viral diseases. In this study, vaccinated and unvaccinated A. salmon parr were exposed to different photoperiodic regimens (1‐, 3‐ or 6‐week continuous light—WCL). Fish groups at different stages in the smoltification process were induced, as demonstrated by differences in morphological and physiological smolt parameters. At the time of seawater transfer, the 6‐WCL group had reached a more pronounced stage in the smoltification process than the 1‐WCL group. In unvaccinated fish, the subsequent cohabitation challenge with infectious pancreatic necrosis virus (IPNV) gave a significantly higher accumulated mortality in the 6‐WCL group (87%) compared to the 1‐WCL group (39%). In the vaccinated groups, this effect was not apparent and there were no differences in accumulated mortality between the 1 WCL, 3 WCL and 6‐WCL groups. These data suggest that the resistance to IPN in A. salmon was negatively influenced by smoltification, while vaccine‐mediated protection to IPN was maintained equally well irrespective of smolt status. 相似文献
9.
Plasma levels of insulin were measured by specific radioimmunoassay in 1-year and 2-year old Atlantic salmon (Salmo salar) parr during the period of parr-smolt transformation. The two-year old fish were of two different categories; silvering pre-smolts
and previously mature male parr. If insulin plays an important role in parr-smolt transformation and/or subsequent osmoregulatory
changes it was expected that the pre-smolts would show a different insulin profile compared to the mature male parr and one-year
old parr, both of which show impaired hypoosmoregulatory ability compared to smolts. Measurements were taken during two separate
years. Between January and April both categories of two-year old fish had generally higher plasma levels of insulin compared
to the non-smolting one-year old parr. In the pre-smolts insulin levels ranged from 4.0 to 7.9 ng ml−1, and from 7.8 to 16.7 ng ml−1 in 1990 and 1992 respectively, while in the previously mature males the same respective values were from 4.3 to 10.0 ng ml−1, and from 6.6 to 24.1 ng ml−1. In the two-year old fish, whether pre-smolts or mature males, plasma insulin levels peaked between 1–2 months before final
smoltification, after which insulin titers declined sharply. In 1990, the 1-year old parr showed a dual peak in plasma insulin.
Insulin first peaked in February (7.8 ng ml−1), and then again in April–May (7.7 ng ml−1), while in 1992 the 1-year old parr showed a number of smaller transient peaks (5–7 ng ml−1) between March–May, followed by sharp elevation of insulin levels in June. Liver glycogen contents were at their highest
(3.5–5.0 g 100 g−1 I liver wet weight) in March in both 1-year and 2-year old fish. Glycogen levels were low during the later stages of parr-smolt
transformation, before rising again in June in both the 1-year old and precociously mature parr, but not in the smolts. 相似文献
10.
The biology of salmon growth hormone: from daylight to dominance 总被引：2，自引：0，他引：2
B.Th. Björnsson 《Fish physiology and biochemistry》1997,17(1-6):9-24
The elucidation of the molecular structure of salmon growth hormone (GH) in the mid-1980's paved the way for a new era of endocrinological research. Establishment of homologous immuno- and receptor-assays have made studies of the secretion, tissue and plasma GH levels, GH turn-over and GH receptor concentrations possible. This overview attempts to summarize the present understanding of the biological roles of GH in salmon. Although the involvement of GH in the regulation of physiological processes throughout the salmon life history has yet to be comprehensively explored, the hormone has already been demonstrated to have several important functions. GH is a principal regulator of somatic growth in salmonids. The growth-stimulating effect of GH is probably integrated with that of insulin-like growth factor I (IGF-I), as in later vertebrates. GH stimulates protein synthesis and improves feed conversion during growth. The hormone also promotes lipid and glycogen breakdown as well as gluconeogenesis, functions which are probably of great importance during starvation when GH levels are seen to increase. During parr-smolt transformation of anadromous salmonids, circulating GH levels appear to be governed by environmental cues. Increasing springtime daylength elevates GH levels, and temperature modulates the photoperiod regulation of GH. The seawater-adapting role of GH during the parr-smolt transformation is complex. In freshwater, GH improves hypoosmoregulatory ability by stimulating branchial Na+,K+-ATPase activity and probably also acts in kidney and intestine. Following seawater entry, GH levels and turn-over increase transiently, probably to further increase seawater tolerance. Accumulating in vitro and in vivo data support the conclusion that GH is involved in the regulation of sexual maturation in salmonids although further studies are needed to establish the exact role of GH in this process. GH increases appetite but it is unclear whether the hormone effects the central nervous system directly, or acts indirectly through metabolic changes. GH increases swimming activity as well as dominant feeding behaviour and diminishes anti-predator behaviour of juvenile salmonids. The GH-induced changes of behavioural patterns imply that there exists an ecological trade-off between high growth rate and long-term survival which may explain why natural fish populations normally grow at sub-maximal rates. Current knowledge indicates that GH is an important and multi-functional hormone in salmon and a central mediator of seasonal changes in physiology and behaviour. The regulatory effects of GH are also of great applied interest as they are likely to affect both product quality in aquaculture and long-term survival of released fish. 相似文献