共查询到20条相似文献,搜索用时 31 毫秒
1.
Steffen S. Madsen 《Fish physiology and biochemistry》1990,8(4):271-279
The growth-independent effect of ovine growth hormone (oGH) and oGH + cortisol treatment on seawater (SW) adaptation in immature
rainbow trout, Salmo gairdneri was investigated. Fish were injected every second day with saline, 2.0 μg oGH/g or 2.0 μg oGH + 8.0 μg cortisol/g for a maximum
of 8 injections in freshwater (FW). Subgroups were transferred to 28‰ SW after 4 or 8 injections, and changes in plasma Na+ and Cl−, muscle water content and gill Na+/K+-ATPase activity were measured. In both of the hormone-treated groups retained in FW, gill Na+/K+-ATPase activity and interlamellar chloride cell density increased. The effects were most pronounced in the oGH + cortisol
group after 2 weeks of treatment. After transfer to SW most of the control fish died due to the osmotic stress, whereas in
the hormone-treated groups, mortality was low and there was a positive correlation between pretransfer gill Na+/K+-ATPase and the ability to maintain ionic-osmotic homeostasis after SW transfer. After two weeks of oGH + cortisol treatment,
gill Na+/K+-ATPase activity was maximal. In contrast, after SW transfer, Na+/K+-ATPase activity increased further in the oGH-treated group. This group regulated ionic-osmotic parameters less effectively
than the oGH + cortisol-treated group. The data indicate that GH and cortisol are important hormones in the regulation of
hypoosmoregulatory mechanisms in S. gairdneri. 相似文献
2.
Steffen S. Madsen 《Fish physiology and biochemistry》1990,8(1):45-52
The effect of cortisol on osmoregulatory parameters was studied in rainbow trout, (Salmo gairdneri), kept in freshwater (FW) and/or transferred to seawater (SW). Repeated injections of 20 μg cortisol/g fish stimulated gill
and gut Na+/K+-ATPase activity and reduced plasma Na+ and Cl− levels after 2 weeks of treatment in FW-adapted fish. Cortisol doses of 0.05 and 1.0 μg/g were without effect. Repeated injections
of 10 μg cortisol/g stimulated gill Na+/K+-ATPase activity and reduced plasma Na+ and Cl− levels in fish in FW, and significantly improved ion regulation after their transfer to 28SW. Higher doses of cortisol (10
and 20 μg/g) induced hyperglycemia, whereas low doses (0.05 and 1.0 μg/g were without effect or induced hypoglycemia. Plasma
glucose levels decreased in cortisol-treated fish transferred to SW, whereas transient hyperglycemia was seen in the control
fish. 相似文献
3.
Cortisol-induced changes in oxygen consumption and ionic regulation in coastal cutthroat trout (Oncorhynchus clarki clarki) parr 总被引:2,自引:0,他引:2
The influence of cortisol on oxygen consumption and osmoregulatory variables was examined in coastal cutthroat trout (Oncorhynchus clarki clarki) parr kept in fresh water (FW) and transferred to seawater (SW). Intraperitoneal implants containing cortisol (50 g g–1) in vegetable oil resulted in elevated plasma cortisol titres similar to those observed in fish following a 24h SW exposure. Cortisol treatment significantly increased the oxygen consumption and plasma glucose levels of trout in FW, consistent with the glucocorticoid role of cortisol. Cortisol treatment did not cause any changes in plasma ion concentrations or gill Na+,K+-ATPase activity in FW after 10 days. Cortisol-implanted fish exposed to SW for 24h showed slightly improved ion regulatory ability compare to non-implanted controls. The results of this study suggest that during SW transfer in juvenile salmonids, increases in cortisol may act as both a mineralocorticoid and a glucocorticoid, depending on the developmental state of the fish (e.g., smolt versus parr). Furthermore, the relative energetic costs of osmoregulation and that of the stress associated SW transfer cannot be discerned using whole-animal oxygen consumption rates. 相似文献
4.
The capacity of cortisol, ovine growth hormone (oGH), recombinant bovine insulin-like growth factor I (rbIGF-I) and 3,3,5-triiodo-l-thyronine (T3) to increase hypoosmoregulatory capacity in the euryhaline teleost Fundulus heteroclitus was examined. Fish acclimated to brackish water (BW, 10 ppt salinity) were injected with a single dose of hormone suspended in oil and transferred to seawater (SW, 35 ppt salinity) 10 days post-injection. Fish were sampled 24 h after transfer and plasma osmolality and gill Na+, K+-ATPase activity were examined. Transfer from BW to SW induced significantly increased plasma osmolality but not gill Na+, K+-ATPase activity. Cortisol (50 g g–1 body weight) improved the ability to maintain plasma osmolality and to increase gill Na+, K+-ATPase activity. oGH (5 g g–1 body weight) also increased hypoosmoregulatory ability and gill Na+, K+-ATPase activity. A cooperation between oGH and cortisol was observed in increasing hypoosmoregulatory ability but not in increasing gill Na+, K+-ATPase activity. rbIGF-I (0.5 g g–1 body weight) alone was without effect in increasing salinity tolerance or gill Na+, K+-ATPase activity. rbIGF-I and oGH showed a positive interaction in increasing salinity tolerance, but not gill Na+, K+-ATPase activity. Treatment with T3 (5 g g–1 body weight) alone did not increase salinity tolerance or gill Na+, K+-ATPase activity, and there was no consistent significant interaction between cortisol and T3 or between GH and T3. The results confirm the classical role of cortisol as a seawater-adapting hormone and indicate an interaction between cortisol and the GH/IGF-I axis during seawater acclimation of Fundulus heteroclitus. 相似文献
5.
Xugang He Ping Zhuang Longzhen Zhang Congxin Xie 《Fish physiology and biochemistry》2009,35(2):223-230
The osmoregulation capabilities of 7-month-old juvenile Chinese sturgeon (Acipenser sinensis Gray) (128.8 ± 15 g) transferred directly from fresh water (0‰, 46 mOsmol kg−1) to brackish water (10‰, 273 mOsmol kg−1) were studied over a 20-day period. Changes in serum osmolarity, chloride (Cl−), sodium (Na+), potassium (K+) and calcium (Ca2+) ion concentrations, as well as gill and spiral valve Na+,K+-ATPase activities were measured at 3, 12, 24, 72, 216 and 480 h after transfer to BW. The serum osmolarity and ion concentrations
(Na+, Cl− and Ca2+) increased immediately after the transference to BW, reaching maximum at 24 h and returned to a new steady state at 216 h,
while the FW control group maintained basal levels which showed lower (P < 0.05) than the BW group. Gill Na+,K+-ATPase activity of BW group exhibited an abrupt decrease in the first 3 h after transfer, but began to increase at 3 h, reaching
a peak value at 24 h, and returned to a new steady state at 216 h. The differences between gill Na+,K+-ATPase activity of BW and FW fish were significant (P < 0.05) after 12 h. In contrast, Na+,K+-ATPase activity of the spiral valve showed transient increase after transference from FW to BW, and then decreased rapidly
at 3 h, reaching the lowest at 24 h after transference. At 216 h after exposure to BW, Na+,K+-ATPase activities of the spiral valve increased slowly to the levels of FW control. The results of our study indicate the
existence of hyposmoregulatory adaptive mechanisms in 7-month-old juvenile Chinese sturgeon which enable this fish to acclimate
itself successfully to brackish water. 相似文献
6.
Fabiana Trombetti Vittoria Ventrella Alessandra Pagliarani Rodolfo Ballestrazzi Marco Galeotti Gianni Trigari Maurizio Pirini Anna Rosa Borgatti 《Fish physiology and biochemistry》1996,15(3):265-274
With the aim of comparing the effects of oral T3 and NaCl administration on trout hypoosmoregulatory mechanisms, three groups of rainbow trout (Oncorhynchus mykiss Walbaum) held in freshwater (FW) were fed a basal diet (C), the same diet containing 8.83 ppm of 3,5,3-triiodo-L-thyronine (T3) (T) or 10% (w/w) NaCl (N) respectively for 30 d. They were then transferred to brackish water (BW) for 22 d and fed on diet C. Gill (Na++K+)-ATPase activity and its dependence on ATP, Na+ and pH, number of gill chloride cells (CC), serum T3 level as well as fish growth, condition factor (K) and mortality were evaluated. During the FW phase, as compared to C trout, T trout showed a two fold higher serum T3 level, had unchanged gill (Na++K+)-ATPase activity and increased CC number, whereas N trout showed higher gill (Na++K+)-ATPase activity and CC number. At the end of the experiment the enzyme activity was in the order T>N>C groups and all groups showed similar CC number. Both treatments changed the enzyme activation kinetics by ATP and Na+. A transient increase in K value occurred in N group during the period of salt administration. In BW, T and N groups had higher and lower survival than C group respectively. Other parameters were unaffected by the treatments. This trial suggests that T3 administration promotes the development of hypoosmoregulatory mechanisms of trout but it leaves the (Na++K+)-ATPase activity unaltered till the transfer to a hyperosmotic environment. 相似文献
7.
Steffen S. Madsen Stephen D. McCormick Graham Young Jeanette S. Endersen Richard S. Nishioka Howard A. Bern 《Fish physiology and biochemistry》1994,13(1):1-11
Several experiments were performed to investigate the physiology of seawater acclimation in the striped bass, Morone saxatilis. Transfer of fish from fresh water (FW) to seawater (SW; 31–32 ppt) induced only a minimal disturbance of osmotic homeostasis.
Ambient salinity did not affect plasma thyroxine, but plasma cortisol remained elevated for 24h after SW transfer. Gill and
opercular membrane chloride cell density and Na+,K+-ATPase activity were relatively high and unaffected by salinity. Average chloride cell size, however, was slightly increased
(16%) in SW-acclimated fish. Gill succinate dehydrogenase activity was higher in SW-acclimated fish than in FW fish. Kidney
Na+, K+-ATPase activity was slightly lower (16%) in SW fish than in FW fish. Posterior intestinal Na+,K+-ATPase activity and water transport capacity (Jv) did not change upon SW transfer, whereas middle intestinal Na+,K+-ATPase activity increased 35% after transfer and was correlated with an increase in Jv (110%). As salinity induced only minor changes in the osmoregulatory organs examined, it is proposed that the intrinsic euryhalinity
of the striped bass may be related to a high degree of “preparedness” for hypoosmoregulation that is uncommon among teleosts
studied to data. 相似文献
8.
The impact of 17-estradiol (E2) and the putative estrogenic compound, 4-nonylphenol (4-NP), on smoltification and vitellogenesis in Atlantic salmon (Salmo salar) was investigated during a 30 day period starting late April. Three groups of fresh water (FW) fish (1 year old, mixed sexes, average weight 23 g) were injected once a week with 50 µg (0.18 µmol) 17-estradiol, 3 mg (13.6 µmol) 4-nonylphenol dissolved in peanut oil, or peanut oil alone as control. Every ten days, subgroups were challenged with 28 ppt seawater (SW) for 24h, and sampled together with subgroups of FW fish. Treatment effects were examined on vitellogenic and osmoregulatory parameters. E2 and 4-NP treatment increased the total calcium and protein level in plasma and the hepatosomatic index of FW fish, both indicating an activated vitellogenesis in the liver. The presence of vitellogenin in the plasma of 4-NP- and E2-treated groups was further indicated by the appearance of a high molecular weight vitellogenin band (550 kDa) in electropherograms produced by native gel electrophoresis. This band appeared in exactly the same position in both the E2- and the 4-NP-treated groups but could not be detected in controls. During the 30 day treatment period, control fish approached the peak of smoltification, as indicated by a distinct silvery appearance, decreasing condition factor, increasing levels of gill Na+,K+-ATPase and improved hypoosmoregulatory performance in the SW-challenge test. Both E2 and 4-NP treatments significantly inhibited the progress of smoltification, as judged by a significant reduction of gill Na+,K+-ATPase activity, relative -subunit Na+,K+-ATPase mRNA expression, gill chloride cell density and a poorer hypoosmoregulatory performance of treated fish. The impaired SW-tolerance of E2- and 4-NP-treated fish was strongly correlated with a decreased gill Na+,K+-ATPase activity. Despite a difference in relative potency, the present study shows that 4-nonylphenol and 17-estradiol may have qualitatively similar inhibitory effects on smoltification and hypoosmoregulatory physiology of Atlantic salmon. Both 4-NP and E2 activated the vitellogenic system, and the study supports the hypothesis that sexual maturation and smoltification are antagonistic, developmental phenomena in salmon. It is suggested that the presence of estrogenic compounds in the environment may negatively influence smoltification and migration in wild stocks of salmon. 相似文献
9.
The mudskipperB. boddaerti, was able to survive in waters of intermediate salinities (4–27). Fish submerged in dechlorinated tap water suffered 60% mortality by the fifth day while 60% of those in 100% sea-water (sw) died after the third day of exposure. After being submerged in 50% or 80% sw for 7 days, the plasma osmolality, plasma Na+ and Cl– concentrations and the branchial Na+ and K+ activated adenosine triphosphatase (Na+,K+-ATPase) activity were significantly higher than those of fish submerged in 10% sw for the same period. However, the activities of the branchial HCO3
– and Cl– stimulated adenosine triphosphatase (HCO3
–,Cl–-ATPase) and carbonic anhydrase of the latter fish were significantly greater than those of the former. Such correlation suggests that Na+,K+-ATPase is important for hyperosmotic adaptation in this fish while HCO3
–-Cl–-ATPase and carbonic anhydrase may be involved in hypoosmotic survival. 相似文献
10.
Morphological changes in gill mitochondria-rich (MR) cells were examined in cultured Japanese eel acclimated to deionized
freshwater (DFW), freshwater (FW), 30%-diluted seawater (DSW), and seawater (SW). The gill Na+/K+-ATPase activity was higher in SW-acclimated eel than in those acclimated to DFW, FW, and DSW. Immunocytochemical observations
revealed that MR cells in the gill filaments were most developed in SW, whereas MR cells in the lamellae were preferentially
observed in DFW, suggesting that filament and lamellar MR cells are responsible for ion secretion and absorption, respectively.
In scanning electron microscopic observations, the apical membrane of lamellar MR cells appeared as a flat or slightly projecting
disk with a mesh-like structure on its surface. In contrast, the apical membrane of filament MR cells showed a slightly concave
surface. Whole-mount immunocytochemistry revealed that most MR cells showed cystic fibrosis transmembrane conductance regulator
immunoreaction in their apical region in fish in DSW and SW, but not in those in DFW and FW, indicating that MR cells developed
in DSW and SW function as an ion-secreting site. In addition to MR cells, distinct Na+/K+-ATPase immunoreaction was observed in the outermost layer of gill epithelia, suggesting that pavement cells are an additional
site of ion uptake in the gills. 相似文献
11.
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
12.
A. Rodríguez M.A. Gallardo E. Gisbert S. Santilari A. Ibarz J. Sánchez F. Castelló-Orvay 《Fish physiology and biochemistry》2002,26(4):345-354
The osmoregulation capabilities of juvenile Siberian sturgeon exposed to three experimental osmolalities (22, 250 and 387 mOsmol kg−1) were studied over a 45-day period. Growth performance, haematological parameters, ion concentrations, gill and spiral valve
Na+-K+-ATPase activities, as well as gill and spiral valve histology, were measured. At the end of the period, the plasma osmolality
of fish kept in 250 and 387 mOsmol kg−1 was higher than that of fish kept in 22 mOsmol kg−1. Similar trends were observed in electrolyte concentrations. Spiral valve and gill Na+-K+-ATPase activity varied with exposure time and environmental salinity. Shortly after being transferred to hyperosmotic media,
spiral valve Na+-K+-ATPase activity fell, while gill Na+-K+-ATPase activity remained constant. At the end of the experiment, gill Na+-K+-ATPase activities in fish kept in isosmotic and hyperosmotic media had increased in comparison to those of the control fish.
Moreover, spiral valve Na+-K+-ATPase activities recovered and were similar to those recorded in fish kept in hyposmotic environments. Although some of
the morpho-physiological mechanisms were operational in juvenile Siberian sturgeon in their adaptation to hyperosmotic media,
fish cannot be considered hyperosmotic regulators as they were unable to maintain their plasma osmolality and electrolyte
equilibrium in salinities higher than 250 mOsmol kg−1. This suggests that the culture of juvenile Siberian sturgeon in brackish environments is unlikely to be successful. However,
our data indicate that in natural environments, juvenile Siberian sturgeon in migratory populations (Ob and Lena Rivers) would
be able to migrate successfully into estuarine brackish grounds with a salinity of up to 9%.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
13.
V. Ventrella A. Pagliarani M. Pirini G. Trigari F. Trombetti A. R. Borgatti 《Fish physiology and biochemistry》1993,12(4):293-304
The response to cold of gill and kidney membrane lipid composition and microsomal (Na++K+)-ATPase, Na+-ATPase and Mg2+-ATPase activities in reared sea bass (Dicentrarchus labrax L.) was investigated. Fish acclimation was carried out according to the seasonal cycle from August to March. No cold-promoted
increase in fatty acid unsaturation was shown in gill and kidney polar lipids and in total lipids of mitochondria and microsomes.
In both tissues the (Na++K+)-ATPase exhibited positive compensation for cold acclimation whereas the Na+-ATPase displayed negative compensation. The Mg2+-ATPase showed no compensation in the gills and positive compensation in the kidneys. During cold acclimation the break in
the Arrhenius plot of the (Na++K+)-ATPase decreased, whereas breaks of both the Na+-ATPase and the Mg2+-ATPase activities remained unchanged. The results indicate that the sea bass does not adopt membrane unsaturation as a cold-facing
strategy. The cold-promoted enhancement of (Na++K+)-ATPase activity in osmoregulatory tissues may be advantageous to maintain efficient osmoregulation under thermodynamically
unfavourable conditions. 相似文献
14.
J. Mark Shrimpton Aurora M. C. Sentlinger John W. Heath Robert H. Devlin Daniel D. Heath 《Fish physiology and biochemistry》2007,33(3):259-268
There is increasing evidence for complex dosage effects on gene expression, enzyme activity and phenotype resulting from induced
ploidy change. In this study, ocean-type chinook salmon were bred using a 2 × 2 factorial mating design to create four families
and test whether triploidization resulted in changes in growth performance and smolting. Eggs were pressure shocked after
fertilization to create triploid fish from a subset of each family. In June, fish were sampled for size, plasma insulin-like
growth factor 1 (IGF-1), gill Na+–K+-ATPase activity, and expression of two Na+–K+-ATPase α subunits in the gill. Diploids were significantly heavier than triploids, and there were significant differences
due to family. Despite a significant positive correlation between plasma IGF-1 and fish size, plasma IGF-1 did not differ
between diploid and triploid smolts. Diploids also had significantly greater gill Na+–K+-ATPase enzyme activities than triploids and there was a strong family effect. Gill Na+–K+-ATPase α1b isoform expression differed significantly by family, but not ploidy, and generally families with lower Na+–K+-ATPase enzyme activity had higher α1b isoform gene expression. Na+–K+-ATPase α1a isoform expression did not differ among any of the groups. Although diploids were larger and had higher specific
activities of Na+–K+-ATPase in the gills, there was no difference in gene expression or circulating hormone levels. The strong family effect,
however, suggests that strain selection may be useful in improving performance of triploids for aquaculture. 相似文献
15.
Cortisol stimulates intestinal fluid uptake in Atlantic salmon (Salmo salar) in the post-smolt stage
Sean C. Cornell David M. Portesi Philip A. Veillette Kristina Sundell Jennifer L. Specker 《Fish physiology and biochemistry》1994,13(3):183-190
The fluid uptake rate of the posterior intestine of salmonids increases during the parr-smolt transformation. Intestinal fluid
uptake in post-smolt Atlantic salmon was investigated after treatment with cortisol and growth hormone (GH), alone or together.
Two replicate experiments were conducted in August 1991 and August 1992. Cortisol was emulsified in vegetable shortening and
vegetable oil (1:1) and implanted into the peritoneal cavity. GH was administered as intraperitoneal injections in a saline
vehicle on days 0 and 2. On days 5 and 6, plasma cortisol levels, gill Na+,K+-ATPase activity, andin vitro measurements of fluid transport rate (Jv) across the posterior intestine were measured. Implants of cortisol elevated the plasma cortisol levels within a physiological
range, and resulted in elevated gill Na+,K+-ATPase activity, as expected. The fluid uptake rate across the posterior intestine was roughly doubled by cortisol treatment.
GH treatment did not affect intestinal fluid transport, gill Na+,K+-ATPase activity, or plasma cortisol concentrations. The seawater-adapting increase in the rate of fluid uptake by the posterior
intestine of smolting salmon is probably stimulated by elevated plasma cortisol concentrations. 相似文献
16.
Sexually immature two-year old Arctic char (Salvelinus alpinus) were implanted with Silastic capsules containing testosterone or 11-ketoandrostenedione in early spring. Seawater adaptability
of the hormone-treated and sham-operated fish was tested periodically from May to August using a 48h seawater challenge test
with 25‰ seawater. The sham-operated control fish displayed a seasonal pattern in seawater adaptation, showing a good hypoosmoregulatory
ability until mid June followed by a marked increase in plasma sodium and magnesium levels in July and August. Gill Na+-K+-ATPase activity decreased concurrently with the observed decrease in seawater adaptability. Over the same period the androgen-treated
fish displayed a similar pattern in seawater adaptability, however, in May and June the plasma sodium levels were significantly
higher in both androgen-treated groups compared to the control group. Plasma magnesium regulation was impaired in both androgen-treated
groups in August. Gill Na+-K+-ATPase activity in the testosterone-treated fish was lower in June compared to the control fish, whereas the activity was
not affected by 11-ketoandrostenedione treatment. The results show that while androgens impair the hypoosmoregulatory capacity
in Arctic char, the seasonal pattern of seawater adaptability is not affected. 相似文献
17.
G. Flik T. Kaneko A.M. Greco J. Li J.C. Fenwick 《Fish physiology and biochemistry》1997,17(1-6):385-396
Biochemical procedures developed to isolate plasma membranes from the branchial epithelium of rainbow trout (Oncorhynchus mykiss) yield membrane fractions that are specifically enriched in the plasma membrane marker enzyme Na+/K+-ATPase. As the bulk of the branchial Na+/K+-ATPase is assumed to be confined to the mitochondria-rich chloride cells, such membrane preparations must contain the essence of the enzymatic machinery of the chloride cells. Basal Na+ activity in branchial (chloride) cells is around 10 millimolar and, accordingly, we find a Km for Na+ of the Na+/K+-ATPase of 13 millimolar, indicating that the enzyme may be regulated by changes in cytosolic sodium. The Na+-gradient across the serosal plasma membrane created by this pump provides energy for 3Na+/Ca2+-exchange and bumetanide-sensitive Na+/K+/2Cl--cotransport. Here we further postulate the presence of a Na+/Cl--cotransporter, indicated by thiazide-sensitive, bumetanide-insensitive transport of Na+ and Cl-; this cotransporter activity awaits the characterization of its kinetics. The Na+/Ca2+-exchanger has kinetic characteristics compatible with a regulatory role of cytosolic Na+ in the activity of this carrier. Both Na+/Ca2+-exchange and Ca2+-ATPase activity may contribute to transport of Ca2+, the former having lower affinity for calcium but a higher capacity than the latter carrier. The Na+/K+/2Cl--cotransporter has kinetics that favor a regulatory role for plasma K+ in the activity of this carrier. Seawater adaptation leads to increased activity of cotransporter molecules in the plasma membrane fractions (the activity increases relative to that of the Na+/K+-ATPase) and this may reflect a function in Cl--extrusion performed by the chloride cells in a seawater environment. A function for the cotransporter in the gills of freshwater fish may be the regulation of cell volume. 相似文献
18.
盐度胁迫对三疣梭子蟹鳃Na+/K+-ATPase酶活的影响 总被引:2,自引:2,他引:0
通过钼蓝法测定三疣梭子蟹在3组实验盐度的胁迫过程中第2对和第6对鳃Na+/K+-ATPase酶活的变化,比较了3组实验盐度胁迫1 d时,鳃Na+/K+-ATPase的酶活大小。结果表明,在盐度胁迫初期,3组实验盐度下第2对和第6对鳃Na+/K+-ATPase的酶活下降;之后,各组实验盐度下第2对和第6对鳃Na+/K+-ATPase的酶活开始随胁迫时间增长而上升;最后,各组实验盐度下第2和第6对鳃Na+/K+-ATPase的酶活下降并趋于稳定。另外,胁迫1 d时,各组实验盐度下三疣梭子蟹前5对鳃Na+/K+-ATPase的酶活显著低于后3对鳃Na+/K+-ATPase的酶活。三疣梭子蟹对盐度变化的调节可分为被动应激期(酶活力下降)、主动调节期(酶活力逐渐上升)和适应期(酶活力稳定);三疣梭子蟹后3对鳃是离子转运、渗透压调节的主要部位。 相似文献
19.
Mitochondria-rich cells in the branchial epithelium of the teleost,Oreochromis mossambicus,acclimated to various hypotonic environments 总被引:1,自引:0,他引:1
Tsung-Han Lee Dr. Pung-Pung Hwang Hui-Chen Lin Fore-Lien Huang 《Fish physiology and biochemistry》1996,15(6):513-523
Branchial mitochondria-rich (MR) cells were examined on the afferent side of gill filaments in tilapia (Oreochromis mossambicus) acclimated to different hypotonic environments, local fresh water (LFW), hard fresh water (HFW) and 5 salt water (SW). Scanning electron micrographs (SEM) identified three types of apical surfaces of the MR cells, wavy convex, shallow basin and deep hole. In spite of the different types of apical surfaces, light microscopic (LM) and transmission electron microscopic (TEM) studies suggested that these cells were MR cells. The relative abundance of these 3 types of branchial MR cells varied with external hypotonic milieus. Wavy-convexed MR cells were dominant in the gills of fish adapted to HFW, whereas shallow-basined MR cells were evident in LFW-adapted fish. In SW-adapted fish, most of the MR cells were deep holes. Experiments on adaptation to various hypotonic milieus revealed that the changes of the branchial MR cells were reversible and occurred within 24 hours following transfer. The morphological alterations of the MR cells correlated with ionic changes in different milieus, indicating that these distinct types of MR cells may play key roles for osmoregulation in hypotonic media. 相似文献
20.
Stephen D. McCormick Christopher D. Moyes James S. Ballantyne 《Fish physiology and biochemistry》1989,6(4):243-254
The effect of seawater acclimation and adaptation to various salinities on the energetics of gill and kidney of Atlantic salmon (Salmo salar) was examined. Smolts and non-smolts previously reared in fresh water were exposed to a rapid increase in salinity to 30 ppt. Plasma osmolarity, [Na+], [Cl–], [K+] and [Mg++] increased in both groups but were significantly lower in smolts than non-smolts. Gill Na+, K+-ATPase specific activity, initially higher in smolts, increased in both groups after 18 days in seawater. Kidney Na+, K+-ATPase specific activity was not affected by salinity in either group. Gill and kidney citrate synthase specific activity was not affected by seawater exposure in smolts but decreased in non-smolts. In a second experiment, Atlantic salmon smolts reared in fresh water were acclimated to 0, 10 or 30 ppt seawater for 3 months at a temperature of 13–14°C. Gill Na+, K+-ATPase was positively correlated with salinity, displaying 2.5- and 5-fold higher specific activity at 10 and 30 ppt, respectively, than at 0 ppt. Kidney Na+, K+-ATPase specific activity was not significantly affected by environmental salinity. Citrate synthase and cytochrome c oxidase specific activities in gill were slightly (6–13%) lower at 10 ppt than at 0 and 30 ppt, whereas kidney activities were lowest at 30 ppt. Oxygen consumption of isolated gill filaments was significantly higher when incubated in isosmotic saline and at 30 ppt than at 0 ppt, but was not affected by the prior acclimation salinity. The results indicate that although high salinity induces increased gill Na+, K+-ATPase activity, it does not induce substantial increases in metabolic capacity of gill or kidney. 相似文献