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91.
Surfacing activity and food utilisation in the obligatory air-breathing fish ophiocephalus striatus as a function of body weight 总被引:1,自引:1,他引:0
E. Vivekanandan 《Hydrobiologia》1977,55(2):99-112
Reared in cylindrical aquaria containing different depths of water (2.5 to 70 cm) the obligatory air-breathing fish Ophiocephalus striatus, belonging to different weight classes (0.1, 0.75, 10, 20 and 41 g), was forced to swim vertically a longer or shorter distance per surfacing. Surfacing frequency was a depth-dependent, activity in individuals weighing less than 20 g in all weight classes, the frequency was nearly 2 times more in the series fed ad libitum on fish muscle, than in the one where the fish were starved. Owing to the sustained surfacing activity and the consequent fatigue, the test individuals hung to the surface for a definite period. Neither frequency nor duration of hanging was depth-dependent. Mean hanging durations for the feeding series were 1.1, 3.8, 5.9, 7.9 and 8.8 hr/day in the 0.1, 0.75, 10, 20 and 41 g weight classes, respectively; the corresponding values for the starving series were 1.3, 15.0, 13.0, 12.7 and 12.8 hr/day. The distance swum by the feeding fish increased from 57 to 681 m/day and from 61 to 507 m/day in the 0.1 and 41 g individuals exposed to the minimum and maximum aquarium depths. Feeding rate, which was a depth-dependent activity, decreased from 280 to 113 g cal/g live fish/day with increasing weight. Rate and efficiency of conversion also decreased with increasing body weight; in larger fish conversion was dependent on volume rather than on depth of the aquarium. O2 uptake of feeding fish was about 6 times higher than the starving ones of the tested weight classes at different aquarium depths.This paper is part of a thesis submitted by the author (from A.P.A. College, PALNI) to Madurai University in partial fulfillment of the requirement of the Ph. D. degree. Contribution No. 12 under a research scheme granted to Dr. T. J. Pandian by the UGC (New Delhi). The author is grateful to Dr. T. J. Pandian for valuable guidance, financial support and encouragements. 相似文献
92.
Bo Lönnerdal Barbara O. Schneeman Carl L. Keen Lucille S. Hurley 《Biological trace element research》1980,2(3):149-158
Rat bile and pancreatic fluid were examined for the presence of low molecular weight zinc complexes. Fluids were collected
separately by cannulation, and zinc distribution in collected samples was analyzed by gel filtration on Sephadex G-50. Most
of the zinc in bile was associated with low molecular weight zinc complexes; only a small amount of zinc was present in the
high molecular weight fraction. In contrast, pancreatic secretions did not contain low molecular weight zinc complexes, but
there were considerable amounts of zinc bound to high molecular weight compounds. The addition of zinc to bile resulted in
an increased amount of zinc in the low molecular weight fraction, while the addition of zinc to pancreatic fluid resulted
primarily in an increase in zinc bound to the high molecular weight components. Like pancreatic fluid, homogenates of pancreatic
tissue had no low molecular weight zinc complex. In rats whose bile and pancreatic fluid were removed and not returned into
the intestine, the amount of zinc bound to low molecular weight complexes in intestinal homogenates was reduced. This alteration
of the molecular distribution of zinc in intestinal homogenates by removal of bile and pancreatic fluid suggests the potential
importance of low molecular weight zinc complexes for zinc homeostasis. 相似文献
93.
A proteolytic enzyme in the gut exudate of the common liver fluke has been purified. The enzyme is specific for globin with a pH optimum of 3.9–4.0 and breaks the protein down to peptides and a small percentage of free amino acids. Collagenase activity at pH 7.5 copurifies with the main globinolytic enzyme. The enzyme has a molecular weight of 12,000 and does not appear to be antigenic in fluke-infected animals. 相似文献
94.
Summary Millet plants (Pennisetum glaucum) were grown at three levels of nitrogen fertilization with and without an inoculum of live nitrogen-fixing Azospirillum cells. The highest average rate of nitrogen fixation as estimated from acetylene reduction by excised preincubated roots was only 23g N2 fixed per ha per day and occurred after treatment with low levels of nitrogen amendment. The average rates of acetylene reduction for intact plants at all treatments were also low. The lack of significant nitrogen fixation due to an Azospirillum-millet association in this study was substantiated by plant dry weight analysis, and determination of the nitrogen content of plants, pot leachate, and soil. There was significant correlation between the total nitrogen content of the plants per pot at the termination of the experiment and the amount of nitrogen fertilizer added initially, but there was no effect of inoculum on final total nitrogen content. 相似文献
95.
Hans-Ulrich Meisch Helga Benzschawel Hans-Joachim Bielig 《Archives of microbiology》1977,114(1):67-70
Cells of Chlorella pyrenoidosa, derived from vanadium free agar slants, respond with great sensitivity to microamounts of vanadium, added as NH4VO3 to autotrophic liquid cultures. Between 0.01 and 1 g V per litre nutrient medium (2·10-10-2·10-8g-at/l), the algae respond with a continuous increase in dry weight. At higher V-concentrations, further enhancement in biomass is accompanied by a additional increase in chlorophyll content. Maximum V-effect on both parameters was found to be at 500g V/l (10-5 g-at/l). Dry weight as well as chlorophyll content of Chlorella are decreased by concentrations above 25 mg V/l; 100 mg V/l (2·10-3 g-at/l) stop growth and cause death of the cells. The toxic threshold for the V-content in the algae was determined to be at 150–200 g V/g (3–4·10-6 g-at/g) dry weight.Two different pH-optima for a positive vanadium action on dry weight and chlorophyll biosynthesis were established, the first at pH 7, the other in the range pH 7.5–8. Two sites of vanadium action in green algae are discussed.Part I: Arch. Microbiol. 105, 77–82 (1975) 相似文献
96.
A highly active inhibitor of the binding of estrone and estradiol-17β to rat alpha-fetoprotein is demonstrated for the first time in embryo, immature and adult rat sera as well as in fetal and adult human sera. The competitive character and the narrow specificity of this inhibition effect is shown. The major compound responsible for this activity is isolated by successive column Sephadex LH20 and thin layer chromatography : it is characterized as a nonpolar, nonphenolic, dialysable and thermostable substance, unreactive towards anti-estrone and anti-estradiol-17β anti-bodies. The possible biological role of an endogenous non-estrogen ligand of rodent fetoproteins is discussed. 相似文献
97.
桃蚜Myrus perslcae、萝卜蚜Lipaphis crystml在能正常产仔的整个恒温范围内,成蚜和新产仔蚜体重随温度的变化都符合二次抛物线,但体重最高值出现较低的温度下.即体重变化主要表现为随温度升高而下降的趋势.在组建蚜虫的生命生殖力表时,以新产仔蚜体重对其在各温度下的生殖事进行校正。并未对计算所得的内禀增长能力rm值及其随温度的变化情况产生明显的影响,不仅没有提供新的信息。相反。这一方法使计算所得rm的值含义模糊。故建议不予采用。 相似文献
98.
Continuous culture system for production of biopolymer levan using erwinia herbicola 总被引:1,自引:0,他引:1
Keith J Wiley B Ball D Arcidiacono S Zorfass D Mayer J Kaplan D 《Biotechnology and bioengineering》1991,38(5):557-560
The optimal production of the fructan biopolymer levan by the bacterium Erwinia herbicola was investigated, including variations in nitrogen, carbon and phosphorous sources, pH, incubation time, culture yields up to 19% by weight produced based on conversion of sucrose as the carbon source when grown in a continuous culture system and processed by tangential flow filtration. Product identity was confirmed with gas chromatography (GC) and (13)C nuclear magnetic resonance (NMR). Gel permeation chromatography (GPC) and low-angle laser light scattering (LALLS) determination of the molecular weight of the product showed a significant difference in molecular weight values dependent on the method of analysis. Analysis by GPC resulted in molecular weight one order of magnitude lower than LALLS independent of sample, underscoring the unusual nature of this biopolymer. 相似文献
99.
Proteasome (multicatalytic proteinase) of sea urchin sperm and its possible participation in the acrosome reaction 总被引:5,自引:0,他引:5
The egg jelly-induced acrosome reaction of the sea urchin, Strongylocentrotus intermedius, was inhibited by succinyl-Leu-Leu-Val-Tyr-4-methyl-coumaryl-7-amide (Suc-Leu-Leu-Val-Tyr-MCA), but not by Suc-Ala-Ala-Pro-Phe-MCA. The proteases with hydrolytic activity toward the former were purified from sperm extract by DEAE-Sephacel and hydroxylapatite chromatographies, Sephacryl S-300 gel filtration, and heparin-Sepharose CL-6B chromatography. Two types of protease were separated, and the molecular weights were estimated to be 65 and 700 kDa, respectively, by gel filtration. The former was accompanied by hydrolytic activity toward Suc-Ala-Ala-Pro-Phe-MCA, which was not hydrolyzed by the latter. Polyacrylamide gel electrophoresis of 700 kDa protease gave a single protein band under nondenaturing conditions and at least eight bands in the range of 22-33 kDa in the presence of sodium dodecyl sulfate (SDS). The substrate specificity and the inhibitor sensitivity of 700 kDa protease indicate that it contains two types of the activity, one is chymotrypsin-type and the other trypsin-type. The former activity was enhanced by poly-L-lysine or SDS. These properties of 700 kDa protease are similar to those of proteasomes (multicatalytic proteinases) isolated from various eukaryotic sources. We had previously shown that inhibitors of chymotrypsin-like proteases inhibit the increase of intracellular Ca2+ concentration by egg jelly, resulting in the inhibition of the acrosome reaction of St. intermedius (Matsumura and Aketa, Gamete Res 23:255-266, 1989). Bringing these findings together, we suggest that the chymotrypsin-like activity of sperm proteasome participates in the onset of the acrosome reaction of St. intermedius. 相似文献
100.
Seasonal fluctuations of zooplankton biomass (dry weight) were determined during a year in two localities of Lake Xolotlán (Managua). Biomass estimations of the most common species of rotifers, cladocerans and copepods were made. The maximal zooplankton biomass was observed in February–April (dry season) in coincidence with the period of highest phytoplankton abundance. Copepods contributed with 78% and 84% to the mean zooplankton biomass at points 1 and 7, respectively. Cladocera biomass was lowest during most of the year, and it was probably controlled by fish predation. Development of rotifer biomass was more intense during the rainy season, when detritus particles were more abundant. Daily fluctuations of zooplankton biomass were not pronounced. 相似文献