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1.
Isolated carp hepatocytes cultured in serum-free, chemically defined medium were used to investigate within the same cell
preparation characteristics of the binding of insulin as well as effects of insulin on cellular metabolism. The binding of
human [125I]-insulin to carp hepatocytes was studied in kinetic, saturation and displacement experiments. A dependency of insulin binding
on the collagenase used for cell isolation was demonstrated. Insulin binding decreased during the first 12h of culture but
remained constant during the following 12h. The kinetic experiments revealed that [125I]-insulin binding reached a steady state within 20–30 min of incubation. The mathematical analysis of the saturation experiments
demonstrated the existence of two populations of binding sites, one with high affinity (Kd1 = 5.5 pM) and low capacity (Bmax1 = 0.14 fmol/mg protein or 77 binding sites/cell) and one with low affinity (Kd2 = 2.4 nM) and high capacity (Bmax2 = 17.6 fmol/mg protein or 9623 binding sites/cell). In competition experiments, 312 pM [125I]-insulin was displaced by cold insulin, IGF-I and IGF-II with IC50 values of 2.2, 7.9 and 20.3 nM, respectively. Glucagon was without effect. Binding of insulin to carp hepatocytes resulted
in a significant reduction of glucose release and a significant increase of protein synthesis as of de novo fatty acid synthesis.
dedicated to Prof. Dr. W. Hanke on the occasion of his 65th birthday. 相似文献
2.
Randi Fritzvold Dr. Birgit H. Dannevig Trond Berg 《Fish physiology and biochemistry》1989,6(6):367-375
A mannose-terminated glycoprotein,125I-invertase, was taken up and degraded by isolated rainbow trout liver cells at 12°C. The uptake was inhibited by EGTA and no degradation occurred in the presence of ammonium ions. The liver cell suspension was fractionated by differential centrifugation in parenchymal and nonparenchymal cells, respectively. The parenchymal liver cells seemed to be the most active cells in uptake of labelled invertase bothin vitro andin vivo. Only negligible amounts of ligand were recovered in the nonparenchymal cells. Internalization of125I-invertase at different temperatures was demonstrated indirectly by releasing surface-bound ligand with EGTA. Ligand was internalized even at 0°C in trout liver cells.In vitro uptake of125I-invertase was inhibited by excess unlabelled invertase, by mannan and by N-acetylglucosamine.These data suggest that invertase is endocytosed by a mannose-specific pathway by the parenchymal liver cells of rainbow trout. 相似文献
3.
Effects of temperature and dietary protein on the growth performance and IGF‐I mRNA expression of juvenile mirror carp (Cyprinus carpio)
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Juvenile mirror carp were fed with five different diets containing 303, 322, 341, 361 and 379 g kg?1 protein and reared at three different water temperatures (18, 23 and 28 °C) for 60 days. We investigated the insulin‐like growth factor I (IGF‐I) mRNA expression, growth performance and the relationship between IGF‐I mRNA expression and the growth performance. The results indicated that the IGF‐I mRNA expression, final body weight, specific growth rate (SGR) and feed efficiency (FE) were enhanced significantly with increasing dietary protein levels (P < 0.05), whereas the protein efficiency ratio, hepatosomatic index (HSI) and viscerosomatic index (VSI) were decreased. Moreover, the IGF‐I mRNA expression, final body weight and SGR were increased significantly with temperature, whereas the HSI and VSI indices were decreased significantly with temperature. Correlation analysis showed that the IGF‐I mRNA expression levels in the brain and liver were positively related to the SGR and FE growth indices (P < 0.01). Finally, the optimal protein requirements for fish growth in different seasons were determined based on the values of SGR and FE, that is 343–348 g kg?1 protein at 18 °C, 354–352 g kg?1 at 23 °C and 371–362 g kg?1 at 28 °C. In this way, we can adjust the dietary protein levels according to culture temperature to reduce any negative impacts on dietary costs and environmental pollution. 相似文献
4.
Richard Skøtt Rasmussen Flemming Hausgaard Larsen Stig Jensen 《Aquaculture International》2007,15(2):97-107
Rainbow trout were studied at different rearing densities, fish sizes and feeding frequencies so that we could evaluate the
effect of these parameters on fin condition, growth and feed utilisation. In one study, two sizes of rainbow trout (18–70 g
or 48–125 g), fed to near satiation at 17.7°C, were examined at two rearing densities (11–41 kg m−3 or 21–92 kg m−3). This study showed that the anal fin was healthier (P < 0.05) at low densities. In the second study rainbow trout were again fed to near satiation and grown from 50 g to 125 g
in 16.4°C water, and they were fed either once daily or three times daily at two densities (18–45 kg m−3 or 54–124 kg m−3). Rainbow trout growth and feed utilisation were slightly but significantly (P < 0.05) reduced at high densities, while dorsal fin condition, surprisingly, was better (P < 0.0001) at the high densities. Possible explanations to these findings are discussed. Condition of the left pectoral fin
was improved at once daily feeding (P < 0.05) compared with three feedings per day, at which fights for feed possibly are more frequent. 相似文献
5.
Y. Durmaz M. Donato M. Monteiro L. Gouveia M. L. Nunes T. Gama Pereira Ş. Gökpınar N. M. Bandarra 《Aquaculture International》2009,17(4):391-399
Diacronema vlkianum was grown in polyethylene bags at two different temperatures (18 and 26°C) in the laboratory. The biochemical composition
level decreased when the temperature increased from 18 to 26°C. The maximum cell number at 18°C was 11.9 × 106 cells ml−1, while maximum cell number at 26°C was 1.6 × 106 cells ml−1. The maximum level of α-tocopherol was 257.7 ± 21.6 μg g−1 dry weight (DW) at 18°C. The highest total carotenoids and chlorophylls were 6.5 mg g−1 DW and 4.3 mg g−1 DW, respectively, and the main pigments were determined as astaxanthin and lutein. Polyunsaturated fatty acids were found
to be the predominant group, reaching 39.5% of the total fatty acids at 18°C. This comprised 20:5(n − 3) as the main polyunsaturated
fatty acids (20.4%, at 18°C) followed by 22:6(n − 3) (4.8%, at 18°C). The results suggest that D. vlkianum can be successfully used as feed in shellfish hatcheries or aquaculture hatcheries, either as a substitute or in association
with other microalgae, when this algae is cultured at 18°C. 相似文献
6.
A particulate fraction obtained from trout testis at the time of spermiation shows saturable binding sites for125I-labeled salmon gonadotropin (125I-GtH). Non-gonadal tissues (liver, muscle and spleen) did not demonstrate specific125I-GtH binding. The tracer's specific activity was determined by the self-displacement method (18 to 30 Ci/g). Maximal specific binding ability of125I-GtH varied from 20 to 30% of the labelled ligand added, depending on the hormone preparation. Specific binding of125I-GtH to 20 mg of the testis membrane varied from 40 to 85% of the total binding depending on the method of membrane prepratation, and was competitively inhibited by concentrations of unlabelled GtH ranging from ca 1 to 1000 ng/ml of incubate. Gonadotropin of mammalian origin, ovine TSH or salmon prolactin competed only weakly, or not at all, for testicular gonadotropin binding sites (relative potencies s-GtH>>FSH=hCG>s-PRL>bTSH). Scatchard analysis of equilibrium binding studies shows that saturable gonadotropin binding was due to a class of high affinity binding sites (sites I Ka3×1010 M–1) and possibly to a second class of lower affinity binding sites (sites II Ka=5 to 14×108 M–1). The binding capacity of sites I, as measured in enriched membrane preparations, was 45±18 fmoles/g of testis during the period of spermiation. The concentration of GtH required to obtain half maximal displacement of125I-GtH in the binding studies was of the same order of magnitude as the apparent ED50 for GtH stimulation of 11-Cetotestosterone (11KT) secretion by trout testesin vitro. Mammalian LH and FSH were 100 to 1000 folds less potent than salmor GtH to increase 11 KT secretion. 相似文献
7.
Interacting effects of dietary lipid level and temperature on growth, body composition and fatty acid profile of rohu, Labeo rohita (Hamilton) 总被引:1,自引:0,他引:1
Three isonitrogenous (320 g kg?1 crude protein, casein and gelatine) semi‐purified diets with 80 (L8), 130 (L13) and 180 (L18) g kg?1 lipid (sunflower oil at increasing levels and cod liver oil fixed at 50 g kg?1) at three digestible energy levels (12 096, 13 986 and 15 876 kJ kg?1 dry weight) and were tested, in triplicate, on rohu fingerlings (3.2 ± 0.08 g) at two different temperatures (21 and 32 °C). Fish were fed to apparent satiation, twice daily, at 09.00 and 15.00 h, 7 days a week for 56 days. Maximum growth was obtained at a lipid level of 80 g kg?1 (L8) at 21 °C (439.37%) and 130 g kg?1 (L13) at 32 °C (481.8%). In general growth rate was higher at 32 °C than at 21 °C at all lipid levels. Tissue monounsaturated fatty acid (MUFA) contents decreased with increasing lipid level at 32 °C, but the reverse occurred at 21 °C. At 21 °C, Polyunsaturated fatty acid (PUFA) level increased significantly (P > 0.05) over initial values, but was affected insignificantly by dietary lipid level. At 32 °C, fish fed diet L13 had more n‐3 fatty acid (FA) in liver and muscle than the other two dietary groups while at 21 °C, both liver and muscle FA profiles exhibited significant change (P > 0.05) in n‐3 and n‐6 FA content which corresponded to variation in percent addition of dietary lipid. However, n‐3/n‐6 ratio was higher for fish fed diet L13 at 32 °C and diet L8 at 21 °C and may be correlated with fish growth. 相似文献
8.
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
9.
T. Matsumoto Y. Nagashima K. Takayama K. Shimakura K. Shiomi 《Fish physiology and biochemistry》2006,31(1):95-100
In vitro accumulation of tetrodotoxin (TTX) and paralytic shellfish toxin (PST) in tiger puffer fish Takifugu rubripes was investigated using liver tissue slices. When T. rubripes liver slices were incubated with Leibovitz’s L-15 medium containing 0.13 mM TTX at 20 °C in air with saturated humidity,
they accumulated 21.5 ± 7.3 μg TTX g−1 liver after the incubation for 12 h and increased to 55.3 ± 8.2 μg TTX g−1 liver at 48 h. In the incubation of T. rubripes liver slices with 0.13 mM PST-containing medium, PST was detected 6.3 ± 0.9 μg g−1 liver at 12 h and reached a plateau thereafter. These results reveal the difference between TTX and PST in accumulation in
T. rubripes liver tissue slices. To examine the variation in PST accumulation among fish species, the liver tissue slices from tiger
puffer fish T. rubripes, parrot-bass Oplegnathus fasciatus and green ling Hexagrammos otakii were incubated at a concentration of 0.027 mM PST. The toxin contents of 3.0 μg g−1 liver were observed at 8 h regardless of fish species but were not increased subsequently, showing no variety among these
three species as to accumulation patterns of PST. It is noted that the tiger puffer fish T. rubripes liver specifically accumulate TTX in preference to PST. 相似文献
10.
Photosynthetic activities of seedlings of Zostera marina were successively measured using a gas volumeter for 6 days at seven light (0–400 μmol photons/m2 per s) and 11 water temperature conditions (5–35°C). The seedlings were collected from mature plants (Ise Bay, central Japan),
and stored and cultured in incubators accurately controlled at each test temperature. The maximum gross photosynthesis (P
maxg) was recorded at an optimal water temperature of 29°C after 0 days. After 6 days, P
maxg appeared at 25°C and most plants cultured at 29–30°C bleached and withered after the drastic increase of light compensation
point (I
c). On the contrary, at 5–28°C, the photosynthetic activities either changed little (5–25°C) or recovered after a temporal
reduction (26–28°C); seedlings survived and looked healthy after being cultured for 6 days. The recovery was thought to be
an acclimation to tolerate higher water temperature. As a result, the critical upper water temperature for Z. marina seedlings was proposed as 28°C. The temperature was consistent with the previously reported maximum water temperature in
habitats around the southern boundary of Z. marina in the northern hemisphere. 相似文献
11.
Effects of temperature and dietary protein on gene expression of Hsp70 and Wap65 and immunity of juvenile mirror carp (Cyprinus carpio)
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Juvenile mirror carp were fed diets containing 303.4, 321.7, 341.2, 361.0 and 379.1 g kg?1 proteins, respectively, and reared at different water temperatures (18, 23 and 28°C) for 60 days. Gene expression of heat shock protein gene (Hsp70) and the warm temperature acclimation‐related 65 kDa protein gene (Wap65), immunity and antioxidant status in the carp were investigated. Results indicated that the contents of serum complement 3 (C3), complement 4 (C4) and immunoglobulin M (IgM), as well as activities of liver superoxide dismutase (SOD) and lysozyme (LSZ) were significantly enhanced with increasing dietary protein (P < 0.05), while content of malondiadehyde (MDA) decreased. Gene expression level of Wap65 in the liver significantly increased with dietary protein, while gene expression of Hsp70 decreased. The contents of C3, C4 and IgM, the activities of SOD and LSZ and gene expression level of Wap65 in the liver significantly increased with temperature. These results suggest that: Serum immune parameter, antioxidant enzymes and Hsp70 and Wap65 expression interact in fish to improve ability to adapt to the environment; and the optimal conditions for the immunity of carp are 348.1?354.5 g kg?1 protein at 18°C, 352.3?364.9 g kg?1 at 23°C and 360.2?364.3 g kg?1 at 28°C, and the optimum temperature for carp is 23°C. 相似文献
12.
The role of glycogen phosphorylase in the regulation of glycogenolysis by insulin and glucagon in isolated eel (Anguilla rostrata) hepatocytes 总被引:1,自引:0,他引:1
The effects of porcine, scombroid, and salmon insulins, and bovine and anglerfish glucagons on glycogen depletion and glycogen
phosphorylase (GPase) activities were examined in freshly isolated American eel (Anguilla rostrata) hepatocytes. Eel liver GPase in crude homogenates was activated (increase in % GPase a) by phosphorylating conditions and was rapidly inactivated (less than 1 h) when a phosphatase inhibitor (fluoride) was absent.
Caffeine inhibits, and AMP activates, the b form of GPase consistent with their effects on rat liver GPase. Both mammalian and fish glucagons increased glucose production
in eel hepatocytes, but had more ambiguous effects on glycogen levels and GPase activities. The magnitude of bovine glucagon
effects were dependent on the initial glycogen content of the cells; only at glycogen concentrations less than approximately
70 μmoles.g−1 did glucagon significantly increase % GPase a. Anglerfish glucagon significantly increased cyclic AMP (cAMP) concentrations by 90% at 10−7 M, but had no effects at 10−9 M and 10−8 M. Scombroid and salmon insulins maintained hepatocyte glycogen concentrations and decreased glucose production, with these
effects more pronounced at low (10−9 to 10−8 M) rather than high (10−7 M) hormone concentrations. Porcine and salmon insulins decreased total GPase and % GPase a activities, and salmon insulin decreased CAMP levels, but only at 10−8 M (by 44%).
Glycogen is, therefore, depleted by glucagon and maintained by insulin in freshly isolated American eel hepatocytes, and these
changes are accomplished, at least in part, by changes in the activities of GPase. Changes in cAMP do not explain all of the
observed hormone effects. 相似文献
13.
Leonardo Susumu Takahashi Ana Paula Baldan & Elisabeth Criscuolo Urbinati 《Aquaculture Research》2006,37(13):1372-1377
Vanadium compounds mimic most of the metabolic effects of insulin, suggesting that it might be useful to improve utilization of dietary carbohydrate. This work evaluated the effect of dietary ammonium metavanadate (H4NO3V) on the growth performance and energy metabolism of pacu, an omnivorous South America characin. Two hundred and eighty‐eight fish were distributed into four blocks according to the body weight (21.8±1.7, 28.5±2.0, 28.4±1.9, 35.7±1.9 g), stocked in 24 plastic tanks and fed twice daily with isonitrogenous and isoenergetic diets containing six levels of H4NO3V (0, 10, 50, 100, 300 and 1000 mg kg?1) for 60 days. Increasing levels of dietary ammonium metavanadate did not improve growth (P>0.05), and the highest level of inclusion (1000 mg kg?1) reduced performance (P<0.05). Blood glucose levels decreased (P<0.05) in fish fed 300 and 1000 mg kg?1 H4NO3V, but no differences were observed in other blood metabolites. A slight increase in muscle lipid content was observed in fish fed a diet containing 300 mg kg?1 H4NO3V. Based on the results of this study, there is no benefit in supplementing pacu diets with metavanadate. 相似文献
14.
Effect of temperature on the development of eggs of round herring Etrumeus teres was experimentally examined to construct a temperature-dependent egg development model. Mature fish were collected in the
field and their eggs were artificially fertilized onboard. The eggs were incubated at nine temperatures set between 14.0 and
25.0°C. All eggs at the lowest three temperatures, 14.0°C, 15.0°C, and 16.0°C, ceased development and died at various stages
before hatching. Durations required to hatching after fertilization ranged from 38.0 h at 25.0°C to 90.0 h at 17.5°C. The
temperature-dependent egg development model, i.e., egg age in hours (y
i,t
) at the ith stage and temperature t (°C), was expressed as: y
i,t
= 4.604 × exp(−0.100 × t −0.129 × i) × i
2.593. From the application of the model to early-stage eggs collected in the field, it is concluded that round herring starts
spawning immediately after sunset and almost completes spawning by midnight. The temperature-dependent egg development model
and the daily pattern of spawning presented in this study are essential tools for developing the daily egg production method
to estimate the spawning stock biomass. 相似文献
15.
Shintaro Imamura Michiko Suzuki Emiko Okazaki Yuko Murata Meiko Kimura Takashi Kimiya Yoshinobu Hiraoka 《Fisheries Science》2012,78(1):177-185
Thaw-rigor is often found in frozen meat of bigeye tuna Thunnus obesus. Excessive amounts of drip loss and stiffness greatly lower the commercial value of tuna meat. In order to prevent thaw-rigor
in meat stored at −60°C post-capture, we adapted a temperature shift technique that stores the meat at −7°C for 1 day or −10°C
for 7 days before thawing. Biochemical changes in muscle of bigeye tuna before and after the temperature shift to −7 or −10°C
were characterized. Contents of ATP, NAD+, glycogen, and creatine phosphate decreased after the temperature shift. NAD+ levels decreased faster than ATP levels and were highly correlated with the rigor index. Thaw-rigor occurred in muscle containing
NAD+ at 1 μmol/g and ATP at 7 μmol/g. On the other hand, the meat color of tuna during frozen storage changed to brown depending
on the storage temperature and reflected the rate of metmyoglobin (met-Mb) formation. Met-Mb formation increase was dependent
on the decrease in NADH levels during the frozen storage. A temperature shift technique with storage at −7°C for 1 day or
−10°C for 7 days before thawing prevented thaw-rigor and met-Mb formation. 相似文献
16.
The effects of animal density and water temperature on the culture of the mysid, Mysidopsis almyra (Bowman), in a static water system were evaluated. An initial set of experiments tested the effects of mysid density on production. Densities of 25, 37.5, 50, 100 and 200 mysids L–1 were placed in trays with 20 L of sea water. Temperatures were maintained at 26 ± 2 °C. A second set of experiments was conducted in the same system at three different temperatures (18 ± 1, 22 ± 1 and 26 ± 2 °C) using a mysid density of 50 mysids L–1 (1000 mysids tray–1). All experiments had a duration of 30 days. The mysids in all trials were cultured at 20 ± 2‰ salinity and fed Artemia nauplii enriched with marine fatty acids. There was a positive correlation between production and mysid densities up to populations of 100 mysids L–1; maximum production was 273 ± 99 hatchlings day–1. At a population density of 200 mysids L–1, high mortality and low production were recorded 4 days after the start of the experiment. The experiments testing different temperatures showed that mysid production was higher at 22 ± 1 °C, although this result was not significant (P > 0.05). Growth rates and hatchling survival after 7 days were significantly higher (P < 0.05) at 26 ± 2 °C compared to survival and growth at 18 or 22 °C. 相似文献
17.
T W K Fraser M S Fleming T T Poppe T Hansen P G Fjelldal 《Journal of fish diseases》2014,37(3):189-200
Heart deformities are a concern in aquaculture and are linked to egg incubation temperature. Diploid and triploid Atlantic salmon, Salmo salar L., were incubated at 6, 8 and 10 °C and analysed for aplasia of the septum transversum (n = 150 ploidy?1 incubation temperature?1). Heart morphology (size and shape) was assessed in fish incubated at 6 °C and in fish with and without aplasia of the septum transversum (n = 9 group?1) incubated at 10 °C. Egg mortality was significantly higher in triploids than in diploids at all incubation temperatures, and increased egg incubation temperatures increased mortality in both ploidy. Triploids grew quicker than diploids after egg incubation at 10 °C, but not at 6 °C. Aplasia of the septum transversum occurred only in triploid fish after incubation at 6 °C and 8 °C (0.7% and 3.3%, respectively) and was significantly greater (P ≤ 0.05) in triploids after incubation at 10 °C compared with diploids (30% and 18%, respectively). Aplasia of the septum transversum significantly increased heart mass and resulted in a long flat ventricle compared with fish displaying a septum transversum. The results suggest triploid salmon should be incubated below 8 °C. 相似文献
18.
Temperature modulates liver lipid accumulation in Atlantic salmon (Salmo salar L.) fed low dietary levels of long‐chain n‐3 fatty acids
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N.H. Sissener B.E. Torstensen M.A.G. Owen N.S. Liland I. Stubhaug G. Rosenlund 《Aquaculture Nutrition》2017,23(4):865-878
Atlantic salmon (Salmo salar) were fed five graded levels of eicosapentaenoic acid (EPA, 20:5n‐3) and docosahexaenoic acid (DHA, 22:6n‐3), from 1.4 to 5.2% of total fatty acids (FA, 5–17 mg kg?1 feed), and grew from ~160 g to ~3000 g, with the period from 1450 g onwards conducted both at 6 °C and at 12 °C. All fish appeared healthy, and there were no diet‐related differences in haematological or plasma parameters, as well as intestinal histological or gut microbiota analysis. Fish reared at 6 °C had higher accumulation of storage lipids in the liver compared to fish reared at 12 °C. Liver lipids also increased with decreasing dietary EPA + DHA at 6 °C, while there was no such relationship at 12 °C. Gene expression of SREBP1 and 2, LXR, FAS and CPT1 could not explain the differences in liver lipid accumulation. In liver polar lipids, DHA was found to be reduced when dietary EPA + DHA was <2.7% of FAs, while the level of EPA in the membranes was not affected. In conclusion, reducing dietary EPA + DHA from 5.2 to 1.4% of total FAs had a minor impact on fish health. Temperature was the factor that most affected the liver lipid accumulation, but there was also an interaction with dietary components. 相似文献
19.
We investigated the effects of open- and closed-system temperature changes on the O2 affinity of Atlantic bluefin tuna (Thunnus thynnus) blood using in vitro methods essentially identical to those previously employed on tropical tuna species. Bluefin tuna blood has a general O2 affinity (P
50 = 2.6–3.1 kPa or 19–23 mm Hg at 0.5% CO2) similar to that of skipjack tuna, yellowfin tuna, and kawakawa blood (P
50 = 2.8–3.1 kPa at 0.5% CO2) but significantly above that of bigeye tuna blood (P
50 = 1.6–2.0 kPa at 0.5% CO2). We therefore hypothesize that bluefin tuna are less tolerant of hypoxia than bigeye tuna. Further, we found the P
50 of bluefin tuna blood to be slightly reduced by a 10°C open-system temperature increase (e.g., from 4.83 kPa at 15°C to 3.95 kPa at 25°C) and to be completely unaffected by a 10°C closed-system temperature change. Bluefin tuna blood, therefore, had a significantly reduced Bohr effect when subjected to the inevitable changes in P
CO
2 and plasma pH that accompany closed-system temperature shifts (0.04–0.09 Δlog P50ΔpH−1) compared with the effects of changes in plasma pH accomplished by changing P
CO
2 alone (0.81–0.94 Δlog P50 Δ pH−1). This response is similar to that of skipjack tuna blood, but different from yellowfin or bigeye tuna blood. During closed-system temperature changes at oxygen levels above P
50, however, bluefin tuna blood showed a reversed temperature effect (i.e., P
O
2 decreased in response to an increase in temperature). Unlike in other tuna species, temperature effects on O2 affinity of bluefin tuna whole blood were similar to those previously reported for hemoglobin solutions, suggesting that red cell-mediated ligand changes are not involved. 相似文献
20.
Michiyasu Yoshikuni Naoki Shibata Yoshitaka Nagahama 《Fish physiology and biochemistry》1993,11(1-6):15-24
Specific binding of [3H]17α,20β-dihydroxy-4-pregnen-3-one (17α,20β-DP) to plasma membranes prepared from defolliculated oocytes of rainbow trout
(Onchorhynchus mykiss) was identified and characterized. Binding was rapid and reached equilibrium in 30 min. 17α,20β-DP strongly inhibited [3H] 17α,20β-DP binding in a competitive manner. Scatchard analysis revealed two different binding sites: a high affinity binding
site with a Kd of 18 nM and a Bmax of 0.2 pmoles/mg protein; and a low affinity binding site with a Kd of 0.5 μM and a Bmax of 1 pmoles/mg protein. This binding activity was successfully solubilized with n-heptyl-β-D-thioglucoside. [3H]17α,20β-DP binding to solubilized preparations reached equilibrium in 1h, and was competitively inhibited with 17α,20β-DP
and 17α,20β,21-trihydroxy-4-pregnen-3-one. However, Scatchard analysis showed a single binding site with a Kd of 0.3 μM. The reason for the disappearance of the high affinity binding site in solubilized preparations remains unclear.
These results demonstrate that a specific binding site for 17α,20β-DP exists in the plasma membrane of rainbow trout oocytes.
Résumé Une liaison spécifique de le [3H]17α,20β-dihydroxy-4-pregnen-3-one (17α,20β-DP), avec des membranes plasmiques d'ovocytes défollicularisés de truite arc-en-ciel (Onchorhynchus mykiss), a été identifiée et caractérisée. Sa cinétique est rapide et atteint son équilibre en 30 minutes. Le 17α,20β-DP inhibe fortement, et de manière compétitive, la liaison de la [3H] 17α,20β-DP. Une étude de Scatchard a mis en évidence deux sites diffŕents de liaison: un site de forte affinité, de Kd 18 nM et de Bmax 0,2 pmoles/mg de protéine; et un site de faible affinité, de Kd 0,5 μM et de Bmax 1 pmoles/mg de protéine. L'activité de liaison a été solubilisée, avec succés, par le n-heptyl-β-D-thioglucoside. Dans la fraction soluble, la liaison de le [3H]17α,20β-DP atteint un équilibre en 1h.; et elle est complétement inhibiée par la 17α,20β-DP et le 17α,20β,21-trihydroxy-4-pregnen-3-one. Cependant, une étude de Scatchard ne permet de déceler qu'un seul site de liaison, de Kd 0,3 μM. La disparition du site de liaison de forte affinité dans la fraction soluble reste inexpliquée. Ces résultats démontrent l'existence d'un site spécifique de liaison du 17α,20β-DP dans les membranes plasmiques des ovocytes de truite arc-en-ciel.相似文献