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71.
Albert Getabu 《Hydrobiologia》1992,232(1):91-97
Length-frequency data collected from fish landings in the Kenya waters of Lake Victoria were used to estimate the growth parameters,
total mortality rate and growth performance index in Oreochromis niloticus. The asymptotic length, (L
∞) and the ratio of the total mortality rate (Z) to the growth constant (K), were estimated to be 64.6 cm and 3.219 respectively. K was 0.254 y-1, Z was 0.818 y-1 and the growth performance index θ′ = Log10
K + 2 log10
L∞ = 3.025, which is rather high as compared to other tilapia populations in natural waters. 相似文献
72.
S. N. Chatterjee R. K. Datta 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1992,85(4):394-402
Summary A detailed analysis was undertaken to test the efficacy of hierarchical agglomerative clustering (UPGMA method) in grouping the races and strains of the mulberry silkworm, Bombyx moti L., and to ascertain the importance of biochemical parameters in the clustering process. The analysis was based on data from two rearing seasons with 54 selected races/strains of different geographic origin and varying yield potentials. The results indicate that seven clusters can be realised with yield parameters alone, whereas the inclusion of biochemical parameters in clustering resulted into two broad groups: one having all the breeds with high cocoon weight and shell weight, the other having all the low-yielding silkworm strains both from India and from other countries. Further sub-grouping under these two groups highlights genetical differences associated with the differentiation of various groups of races in temperate and tropical areas as well as their significance for silkworm breeding. Estimates of all ten variables were further subjected to quick clustering and the results showed that cluster 5, constituted by 38 lowyielding strains of India, China and Europe, had the highest values of the final cluster centre for amylase and the effective rate of rearing (ERR), while clusters 1 and 4 had the highest values for invertase and alkaline phosphatase. The evolutionary aspect of the genetic channelisation of silkworm races from various countries is discussed against the background of differences in the biochemical parameters and yield variables. 相似文献
73.
A circular dichroism-based detection system presents several advantages in the HPLC analysis of chiral compounds because of the selective monitoring of optically active molecules. Its use allows reliable determination of enantiomeric excesses and elution order. To this end, the application of empirical, semiempirical, and nonempirical methods to get stereochemical information from the CD signal is reported. Furthermore, recording the CD spectra on line and evaluation of the dissymetry factor make the CD detection very powerful in characterizing the stereochemistry of chiral eluates. 相似文献
74.
V. Ramamurthy S. P. Thacker R. M. Kothari 《Journal of industrial microbiology & biotechnology》1992,9(2):121-125
Summary A 25-l scale protocol is devised for the optimal secretion and recovery of fungal cellulase. Using a selected higher yieldingTrichoderma viride SMC strain, a protocol consisted of: a) an optimized production medium rich in microcrystalline cellulose (MCC), fortified with 1% (w/v) ammonium sulphate, 0.5% (w/v) soybean flour, 0.1% (v/v) Tween-80 and other trace nutrients; b) optimized physical parameters of production, such as an inoculum containing a homogeneous suspension of 6×107 conidia per 1,28±1°C, pH 4.0±0.5, 300±20 rpm, 11000±1000 l/h aeration, and 170–220 h duration; c) optimal recovery through a filter press (450 l/h rate of filtration) followed by precipitation with 2.5–3.0 volumes of acetone (15°C and basket centrifugation (27°C, 1700 rpm)); and d) vacuum drying (35°C, 4–6 h). This afforded 70% recovery of cellulase in the form of white fluffy powder containing 20000±2000 carboxy methyl cellulase and 1000±50 units filter paperase per g activities, with raw material cost of US$ 8–10 per million carboxy methyl cellulase units. During storage for 18 months at 4°C, ambient temperature and 37°C, the cellulase preparation was found to retain 100, 75 and 60% of its initial activity, respectively. 相似文献
75.
Sciatin Is a Transferrin-Like Polypeptide 总被引:4,自引:0,他引:4
George J. Markelonis Ralph A. Bradshaw Tae H. Oh Jeri L. Johnson Owen J. Bates 《Journal of neurochemistry》1982,39(2):315-320
Abstract: Sciatin, an acidic glycoprotein from chicken sciatic nerve, has myotrophic effects on avian skeletal muscle cells in culture. As sciatin was found to have certain structural similarities to transferrin, we further investigated the physicochemical characteristics of sciatin in order to determine the relationship between these two proteins. Sciatin was found to be strikingly similar to ovotransferrin in amino acid composition. In addition, amino acid sequence analysis revealed that sciatin and ovotransferrin had identical amino-terminal sequences for at least the first 20 amino acid residues. Chicken ovotransferrin, but not human serum transferrin, cross-reacted with rabbit antisciatin antibodies upon rocket immunoelectrophoresis and double immunodiffusion in agar. In addition, in the presence of bicarbonate, sciatin bound approximately 2 mol ferrous iron/mol protein. Using the purification procedure developed for sciatin, we purified a protein from chicken serum that cross-reacted with antisciatin serum, migrated at a position identical to that of sciatin or ovotransferrin on two-dimensional gel electrophoresis, had an amino composition very similar to ovotransferrin and sciatin, and had myotrophic effects on cultured muscle cells. From these data, we conclude that sciatin is a growth-promoting polypeptide closely related in structure to transferrin. 相似文献
76.
Françoise Giraud Michel Claret K.Richard Bruckdorfer Bernadette Chailley 《生物化学与生物物理学报:生物膜》1981,647(2):249-258
Cholesterol depletion alters the apparent affinity of the internal cationic sites and the maximal translocation rate but not the affinity of the external cationic sites of the pump in human erythrocytes. To test whether these effects were mediated by a direct cholesterol-internal site interaction or by a change in membrane lipid order, the effects of five fluidizing amphiphiles (chlorpromazine, imipramine, benzyl alcohol, sodium oleate and sodium benzenesulphonate) on the kinetic parameters of the pump were determined. The cholesterol removal and all the agents used induced dose-response decreases in membrane lipid order as measured by fluorescence polarization or ESR. Positive and neutral amphiphiles mimicked the effects of cholesterol removal on the affinity of the internal sites of the pump and to a lesser extent on the maximal translocation rate. Anionic amphiphiles had no effect on internal sites, probably because they distributed preferentially within the outer leaflet on the membrane. These results indicate that cholesterol controls the affinity of the internal sites of the pump by altering the membrane lipid order. In contrast, neither cholesterol depletion nor the agents used altered the affinity of the external sites of the pump. This difference in sensitivity to membrane lipid order suggests that internal and external cationic sites, although borne by the same protein, are in different lipid environments. 相似文献
77.
An ecological study of the rotifer species Trochosphaera solstitialis (Thorpe, 1893) was conducted for a period of eight months in a temporary pond in eastern Texas, U.S.A. The pond was found to be environmentally stressed and contained large amounts of decomposing vegetation. Physico-chemical factors contributing to the stressed conditions were low dissolved oxygen concentrations, low pH values, high ammonia concentrations, and high color values caused by large concentrations of iron, tannin and lignin. Large concentrations of iron, tannin, and lignin seem to be highly correlated with T. solstitialis populations. Physicochemical conditions probably eliminated predators of the rotifer, such as fish. Males of T. solstitialis were observed which never left the body cavity of the female. Males probably do not feed with an apparent rudimentary digestive system. 相似文献
78.
79.
Measurements made in fresh water wetland have shown that temperature, pH, dissolved oxygen and bicarbonate alkalinity in the hyacinth infested area were lower, but dissolved free carbon dioxide concentration was excitingly greater than in the open water area. This extreme hypoxic and hypercarbic condition of hyacinth covered areas was caused by the thick coverage of Eichhornia crassipes which was crucial for the composition of the characteristic flora and fauna. 相似文献
80.
Abla A. Creasey Helene S. Smith Adeline J. Hackett Kimie Fukuyama William L. Epstein Stewart H. Madin 《In vitro cellular & developmental biology. Plant》1979,15(5):342-350
Summary Three human melanoma cell lines derived from one primary and two metastatic tumors from three different patients were characterized
for growth properties usually associated with malignant transformation; these include cell morphology, growth rate, saturation
density, growth in semisolid media, colony-forming ability on contact-inhibited monolayers of normal fibroblasts and epithelial
cells, and tumorigenicity in immunosuppressed mice. Variations in expression of aberrant properties were evident among the
lines. One of the metastatic lines satisfied all the parameters of malignancy tested and the other showed a number of these
properties, whereas the primary essentially fulfilled only one. These results suggest that cultured melanoma cells reflect
the clinical variability often observed among melanoma patients and the metastatic melanoma seems to display a higher degree
of malignant transformation than the primary.
THis work was supported in part by USPHS Grant No. 5 T01 AI00332-06 from the National Institutes of Health, Contract E73-2001-N01-CP-3-3237
from the Virus Cancer Program of the National Cancer Institute, and USPHS Grant No. 0H00714-02 from the National Institute
for Occupational Safety and Health. 相似文献