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1.
Detailed measurements of gill area and constituent variables (total filament number, total filament length and mean filament
length), and immunolocalization of the α-subunit of Na+/K+-ATPase and Na+/K+-ATPase activity were performed on both hemibranchs of all five arches of freshwater potamotrygonid stingrays (Paratrygon aiereba and Potamotrygon sp.). Both species exhibit similar mass-specific gill area, 89.8 ± 6.6 and 91.5 ± 4.3 mm2 g−1 for P. aiereba and Potamotrygon sp., respectively. The density of Na+/K+-ATPase-rich MRCs and Na+/K+-ATPase activity was higher in the 4th gill arch in both species. The Na+/K+-ATPase activity was positively correlated to the Na+/K+-ATPase-rich (Na+/K+-ATPase rich) mitochondrion-rich cell (MRC) distribution among the gill arches of P. aiereba but not in Potamotrygon sp. The levels Na+/K+-ATPase activity were not correlated to the gill surface area among the arches for both rays’ species. Considering that the
Na+/K+-ATPase-rich MRC is the main site for active ion transport in the gill epithelia and Na+/K+-ATPase activity plays a crucial role in osmoionoregulatory function, we suggesting that 4th gill arch is more relevant for
osmoregulation and ion balance in these potamotrygonids. 相似文献
2.
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
3.
Opposite patterns of branchial Na+/K+-ATPase (NKA) responses were found in euryhaline milkfish (Chanos chanos) and pufferfish (Tetraodon nigroviridis) upon salinity challenge. Because the electrochemical gradient established by NKA is thought to be the driving force for
transcellular Cl− transport in fish gills, the aim of this study was to explore whether the differential patterns of NKA responses found in
milkfish and pufferfish would lead to distinct distribution of Cl− transporters in their gill epithelial cells indicating different Cl− transport mechanisms. In this study, immunolocalization of various Cl− transport proteins, including Na+/K+/2Cl− cotransporter (NKCC), cystic fibrosis transmembrane conductance regulator (CFTR), anion exchanger 1 (AE1), and chloride channel
3 (ClC-3), were double stained with NKA, the basolateral marker of branchial mitochondrion-rich cells (MRCs), to reveal the
localization of these transporter proteins in gill MRC of FW- or SW-acclimated milkfish and pufferfish. Confocal microscopic
observations showed that the localization of these transport proteins in the gill MRCs of the two studied species were similar.
However, the number of gill NKA-immunoreactive (IR) cells in milkfish and pufferfish exhibited to vary with environmental
salinities. An increase in the number of NKA-IR cells should lead to the elevation of NKA activity in FW milkfish and SW pufferfish.
Taken together, the opposite branchial NKA responses observed in milkfish and pufferfish upon salinity challenge could be
attributed to alterations in the number of NKA-IR cells. Furthermore, the localization of these Cl− transporters in gill MRCs of the two studied species was identical. It depicted the two studied euryhaline species possess
the similar Cl− transport mechanisms in gills. 相似文献
4.
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
5.
Talas ZS Orun I Ozdemir I Erdogan K Alkan A Yilmaz I 《Fish physiology and biochemistry》2008,34(3):217-222
The main purpose of this study is to discuss the effect of Cd+2, Cr+3 and Se metals on biochemical parameters in liver tissue of Oncorhynchus mykiss. The rainbow trout were exposed to heavy metal stress (Cd+2, Cr+3) at 2 ppm dosage. The present study was undertaken to determine the protective effect of selenium treatment at the same dosage
(2 ppm) on some biochemical parameters. The activity of catalase (CAT), glutathione peroxidase (GSH-Px), superoxide dismutase
(SOD) and the changes in levels of malondialdehyde (MDA) from biochemical parameters were determined in liver tissue of the
fish groups exposed to heavy metals, especially for the selenium-applied groups. Results of this study showed that the activities
of CAT, GSH-Px and SOD in the tissues of fish exposed to the stress of Cd+2 and Cr+3 were significantly lower than the control groups (P < 0.05). Meanwhile, the closer values to the control groups were obtained in selenium-added groups (Cr+3 + Se+4, Cd+2 + Se+4). For the level of MDA, the last production of lipid peroxidation showed increases (P < 0.05) in the groups exposed to the metal stress, whereas significant decreases were obtained in selenium-applied groups.
The result of the statistical evaluation showed that the negative effects occurring in the biochemical parameters of the applied
groups exposed to the toxicity of heavy metal were significantly eliminated (P < 0.05) as a result of selenium treatment. 相似文献
6.
In the present study, multibiomarker effects of the river water of three representative sections in Nanjing section of the
Yangtze River were investigated in goldfish (Carassius auratus). The organic toxicants were extracted from the water samples using solid phase extraction. Acetylcholinesterase (AChE),
glutathione-S-transferase (GST), 7-ethoxyresorufin-O-deethylase (EROD), glutathione peroxidase (GPx) and Na+/K+-ATPase activities were determined after exposure of the extracted components. The fractions of water samples from three sections
(Daqiao, Sanchahe and Jiangxinzhou) altered these enzymatic activities. With the change of the extracts polarity, the levels
of AChE, GST, EROD, Na+/K+-ATPase activities were different. The responses of enzymatic activities were mostly significant for those exposures of intermediate
polar components (50–80% methanol extracts) and weakly polar components (ether and ether/hexane extracts). It has been shown
that toxicants were mainly concentrated in these fractions in the Yangtze River (Nanjing section). With regard to response
for different sections, EROD and GST activities seem to be more sensitive biomarkers. Integrated biomarker response index
(IBR) were calculated and used to evaluate an integrated impact of pollutants from different sampling sections. The order
of negative biological effects of the three sections was Jiangxinzhou > Sanchahe > Daqiao. The wild fish living in Nanjing
section of the Yangtze River were at potential ecological risk. 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.
Stephen D. McCormick Richard L. Saunders Arthur D. MacIntyre 《Fish physiology and biochemistry》1989,6(4):231-241
Atlantic salmon (Salmo salar) exposed to either simulated natural photoperiod (SNP) or continuous light (L24) were used to examine developmental changes in the presence and absence, respectively, of the parrsmolt transformation. Plasma osmolarity and ion concentrations were unaffected by photoperiod treatment. Gill Na+, K+-ATPase specific activity increased 150% between February and June in SNP fish and was low and unchanged in L24 fish. Kidney Na+, K+-ATPase specific activity varied within similar, narrow limits in both groups. Citrate synthase of liver, gill and kidney, expressed as specific activity or activity/g total body weight (relative activity), increased 25–60% between March and June in SNP fish. With the exception of kidney relative activity, citrate synthase activity declined to initial (March) levels by August. Liver, gill and kidney cytochrome c oxidase activity of the SNP group underwent similar though less marked changes. Liver, gill and kidney citrate synthase and cytochrome c oxidase activities of the L24 group remained relatively constant between March and August, and where significant differences occurred, they were lower than those of the SNP group. These results indicate that respiratory capacities of the liver, gill and kidney increase in smolls concurrent with preparatory osmoregulatory changes, and subsequently decline. The findings are consistent with a hypothesized transient increase in catabolic activity during the parr-smolt transformation that may be due to the metabolic demands of differentiation. 相似文献
9.
Mohammad Ali Jalali Seyed Abbas Hosseini Mohammad Reza Imanpour 《Fish physiology and biochemistry》2010,36(3):555-564
This study was carried out to examine the effect of Artemia urmiana nauplii enriched with HUFA, and vitamins C and E on stress tolerance, hematocrit, and biochemical parameters of great sturgeon,
Huso huso juveniles. Cod liver oil (EPA 18% and DHA 12%), ascorbyl-6-palmitate and α-tocopherol acetate were used as lipid, and vitamin
C and E sources, respectively. Beluga juveniles at the stage of first feeding (69.7 ± 5.9 mg body weight) were randomly divided
into five treatments and three tanks were assigned to each diet. All fish groups were fed non-enriched Artemia for the initial 5 days and then fed enriched Artemia for 7 days. Juveniles were fed with Artemia enriched with HUFA + 20% vitamin C (C group); HUFA + 20% vitamin E-enriched Artemia nauplii (E group); HUFA + 20% vitamin C + 20% vitamin E (C and E group); HUFA without vitamins (HUFA) and non-enriched Artemia (control). After the period of enrichment, Juveniles were fed with Daphnia sp. from the 13th to the 40th day. At day 40, the fish were transferred directly from fresh water (0.5 ppt) to brackish water
(6 ppt for 4 days and 12 ppt for 2 days) and warm water (from 27 to 33°C) to evaluate juvenile resistance to salinity and
thermal shocks. Moreover, all treatments were separately exposed to freshwater in tanks with the same capacity as used for
osmotic and thermal tests (as fresh water control). The addition of vitamins C, E, and C + E to HUFA significantly increased
fish resistance to 12 ppt salinity and temperature stress tests, whereas survival was not significantly different among challenges
at 6 ppt. There was no significant difference in the hematocrit index under stress conditions. Enrichment had significant
influence on plasma Na+ level in the C group on the 4th day at 6 ppt. Na+ and Ca2+ concentrations in C, E, and C and E groups on the 1st day at 12 ppt, and Ca2+ level in E group on the 2nd day at 12 ppt were lower than the other groups. The glucose level in the C and C and E groups
was lower than the other treatments on the 1st day at 12 ppt and the 2nd day at 33°C. Regardless of Artemia enrichment, plasma ions (Na+, K+, Ca2+, and Mg2+) and glucose concentrations in fish exposed to salinity stress tests were higher than fish in fresh water. Glucose concentration
in plasma also increased after 2 days at 33°C. Although most of our results were not significantly different, the use of vitamins
C, E, and HUFA in Artemia enrichment can improve Juveniles tolerance under stress conditions, and regardless of enrichment, these data show that beluga
juveniles are partly sensitive to high salinity and temperature. 相似文献
10.
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
11.
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
12.
盐度对条石鲷幼鱼Na+/K+-ATP酶活力的影响 总被引:2,自引:2,他引:0
研究了盐度变化对条石鲷幼鱼鳃、肾脏和肝脏中Na+/K+-ATP酶活力的影响。经不同盐度(8、18、28、38、48)的处理,条石鲷幼鱼3种组织Na+/K+-ATP酶活力均受到不同程度的影响。经低盐度(8和18)处理的幼鱼鳃Na+/K+-ATP酶活力在前6 h略微增加,然后逐渐降低,在处理24 h时下降到最低,之后又开始增加。经高盐度(38和48)处理时,鳃中Na+/K+-ATP酶活力在前6 h有所降低,然后迅速升高,并在处理24 h时达到最大,之后酶活力逐渐降低,并在处理96 h后与对照组无显著性差异(P>0.05)。所有盐度处理组幼鱼肾脏Na+/K+-ATP酶活力在处理开始6 h均稍有增加,而从处理6 h开始降低,在处理24 h下降到最低,此后酶活力又呈现增加的趋势。在盐度为8的处理组中,肝脏Na+/K+-ATP酶活力与肾脏中变化趋势相似,而其它3组则逐渐降低,在处理24 h时达到最低,之后又逐渐增加。结果表明,条石鲷幼鱼适盐范围广,具有较强的渗透压调节能力。3种组织的Na+/K+-ATP酶活力酶活性在盐度为18~38的范围内变化不明显,而在8和48的盐度下变化较大,最终酶活力均高于对照组。与肾脏相比,盐度变化对鳃和肝脏Na+/K+-ATP酶活力的影响较大。 相似文献
13.
The physiological response of Mozambique and Nile tilapia transferred from fresh to brackish (15 ppt) water was compared during
a one-week time course. Response in the pituitary was measured by the gene expression pattern of prolactin (PRL I), growth
hormone (GH), and calcium-sensing receptor (CaSR), while the response in the gills was measured by the gene expression pattern
of the prolactin receptor (PRL-R), Na+/K+/2Cl− cotransporter (NKCC) and Na+/Cl− cotransporter (NCC), and by activity and expression of Na+/K+-ATPase (NKA). The time-course curves of plasma osmolality levels indicate a rapid elevation 24 h after transfer, which later
decreased and maintained at stable level. PRL I expression decreased in both species, but with stronger response in the Nile
tilapia, while no differences were found in the slightly elevated levels of GH mRNA. The branchial response demonstrated a
faster up-regulation of NKA and NKCC in the Mozambique tilapia, but similar levels after a week, while Nile tilapia had stronger
and constant down-regulation of NCC. The time-course response of the measured osmoregulatory parameters indicate that 24 h
after transfer is a critical time point for brackish-water adaptation. The differences in responses to saltwater challenge
between Mozambique and Nile tilapia shown in this study may be associated with the differences in saltwater tolerance between
these two tilapiine species. 相似文献
14.
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
15.
The effects of the Na+/K+ and Mg2+/Ca2+ ratios in saline groundwaters on Na+-K+-ATPase activity, survival and growth of Marsupenaeus japonicus postlarvae were investigated. The results indicate that the Na+-K+-ATPase activity, survival rate and weight gain of postlarvae were significantly affected by the Na+/K+ and Mg2+/Ca2+ ratios (P < 0.05). The Na+-K+-ATPase activity of postlarvae, in every treatment, changed corresponding to Na+/K+ and Mg2+/Ca2+ ratios, and came to a stable level after 24 h. There was a negative relation between Na+-K+-ATPase activity and Na+/K+ ratio, while there was a positive relation between Na+-K+-ATPase activity and Mg2+/Ca2+ ratio. Compared with seawater (the Na+/K+ and Mg2+/Ca2+ ratios are 27.8 and 4.64 respectively), the Na+-K+-ATPase activity of the Na+/K+ ratio 30 treatment showed no significant difference, while the Mg2+/Ca2+ ratio 4.5 treatment showed distinct difference. The survival rates and weight gain of postlarvae increased markedly when the suitable amount of K+ and Ca2+ was added to test water, and arrived at their maximum in the Na+/K+ ratio 20-30 or Mg2+/Ca2+ ratio 4.5 treatment, having no significant difference compared with normal seawater. Therefore, considering the Na+/K+, Mg2+/Ca2+ ratios and the absolute concentration of Mg2+, Ca2+ in the experimental saline groundwaters applied to Marsupenaeus japonicus farming, it should be modulated to around 30, 4.5 and 1312 mg/l, 291 mg/l, respectively. 相似文献
16.
Kazem Darvish Bastami Mohammad Reza Imanpour Seyed Hossein Hoseinifar 《Aquaculture International》2010,18(5):771-776
The spermatozoa of oviparous fish, such as feral carp (Cyprinus carpio), are immotile in the presence of semen plasma or isotonic solutions, and to obtain good motility, they must be diluted with
suitable medium. The objective of this study was to identify the best activating solution for feral carp sperm. Sperm motilities
were compared in the new activating solution (a): (50 mM NaCl, 30 mM KCl, 30 mM Tris, pH = 8.5) and activating solution (b):
(50 mM NaCl, 40 mM KCl, 30 mM Tris, pH = 8.5) based on effect of pH with everyone of Na+ and K+ ions versus four other activating solutions Billard’s saline solution, Poupard’s saline solution, distilled water and hatchery
water that is routinely used for extending carp semen. Our results showed that maximum total motility period and percentage
of motile sperm were seen in selected saline solution (a). The present study describes an activating solution that prolongs
feral carp sperm motility. 相似文献
17.
18.
Boleophthalmus boddaerti submerged in 10%, 50% and 80% seawater (sw) for 7 days, had whole body transepithelial potentials (TEP) of 3.3, 18.3 and 22.9 mV, respectively. Hypophysectomy significantly decreased the TEP ofB. boddaerti and reversed the polarity of the TEP of the fish exposed to 10% sw.Hypophysectomy also significantly decreased the branchial Na+-K+ activated adenosine triphosphatase (Na+,K+-ATPase) activity but increased the activity of branchial HCO3
–-Cl– stimulated adenosine triphosphatase (HCO3
–,Cl–-ATPase) inB. boddaerti exposed to 10% sw. However, survival in 10% sw was not significantly impaired by hypophysectomy and no significant change in plasma osmolality and plasma Na+ and Cl– concentrations was observed.Various doses of ovine-prolactin or salmon-prolactin were unable to restore the TEP of hypophysectomizedB. boddaerti in 10% sw to that of the sham-operated fish. However, cortisol increased TEP to a positive value in hypophysectomizedB. boddaerti, though it was still lower than the sham-operated control. Cortisol treatment also affected the plasma osmolality, plasma Na+ and Cl– contents and branchial Na+,K+-ATPase and HCO3
–,Cl–-ATPase activities. Overall, the hormonal control of osmoregulation inB. boddaerti appeared to differ from that of other teleosts. 相似文献
19.
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
20.
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