Author Keywords: Acclimation; 14C-choline incorporation; environmental temperature; fatty acid; molecular species; 32P incorporation; phosphatidyl-choline; trout 相似文献
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991.
Two hundred and thirty three samples of lamb carcasses, livers, kidneys and faeces, collected at a local abattoir, were examined to determine the incidence of motile Aeromonas spp. Wash water from the abattoir was also tested. Direct plating on starch ampicillin agar and enrichment in alkaline peptone water were used. The incidence of aeromonads was low. They were detected only after enrichment in 5/47 faecal samples and 11/50 carcass samples. The 41 strains of Aeromonas isolated were identified to species level and 93% of them were able to grow at 5 degrees C. The ability to produce both haemolysin and enterotoxin was species-related and was more common in Aeromonas hydrophila and A. sobria strains than in A. caviae strains. 相似文献
992.
Cell fusion resulting in zygote giant cell formation is the first observable event of sexual development in D. discoideum. The results reported here show that this process is Ca2+-dependent and that by increasing the level of Ca2+ in the medium the number of cell fusions can be increased 57-fold over control cultures. The data also suggest that Ca2+ has both an early and late function in the development of zygotes and these functions are mediated at the cell surface. These results plus the availability of a liquid culture for generating large volumes of cells make sexual development in D. discoideum an excellent system for the analysis of membrane fusion in eukaryotes. 相似文献
993.
Gafur A Tanaka C Shimizu K Ouchi S Tsuda M 《The Journal of General and Applied Microbiology》1998,44(3):217-223
Cochliobolus heterostrophus Tub1 described here is the first beta-tubulin gene characterized from a naturally occurring benomyl-resistant ascomycete plant pathogen. The gene encodes a protein of 447 amino acids. The coding region of Tub1 is interrupted by three introns, of 116, 55, and 56 nt, situated after codons 4, 12, and 53, respectively. As a result of the preference for pyrimidines in the third position of the codons when a choice exists between purines and pyrimidines, codon usage in the Tub1 gene is biased. Tub1 shows high homology with beta-tubulin genes of other ascomycete species. However, Tub1 is exceptional in having Tyr(167), compared with Phe(167), possessed by beta-tubulin genes of other ascomycetes sequenced thus far. The Tyr(167) residue has been associated with benomyl resistance in other organisms. In contrast, all other benomyl-implicated residues of Tub1 correspond to sensitivity. Based on these results, we suggest that benomyl resistance in the fungus probably is attributed to Tyr(167). 相似文献
994.
Robert P. Finch Abdul Baset Inez H. Slamet Edward C. Cocking 《Plant Cell, Tissue and Organ Culture》1992,30(1):31-39
A method was developed for the in vitro clonal propagation of shoots from a range of wild rice and other grass species that have important genetic traits such as drought resistance and salinity tolerance. The axenic multiple shoot cultures, which were suitable for DNA and protein extraction or direct protoplast isolation, could be maintained without subculture for between 2 and 3 months or rapidly multiplied for the subsequent production of mature plants and seeds. Basal sections of the micropropagated shoots also provided novel explants for the production of highly embryogenic callus, from some species, that could be regenerated into green plants. It is envisaged that this clonal propagation technique could aid the genetic manipulation of cultivated rice by providing a means to vegetatively conserve valuable genetic resources, a technique to rapidly multiply novel hybrid material and a source of embryogenic callus that will allow the application of biotechnological techniques, such as somatic hybridization and genetic transformation, to previously unexploited species.Abbreviations BA
N6-benzyladenine
- 2,4-d
2,4-dichlorophenoxyacetic acid
- NAA
-naphthaleneacetic acid
- PAR
photosynthetically-active radiation 相似文献
995.
A study was made of enzymes of carbohydrate metabolism in representative thiobacilli grown with and without glucose. The data show that Thiobacillus perometabolis possesses an inducible Entner-Doudoroff pathway and is thus similar to T. intermedius and T. ferrooxidans. T. novellus lacks this pathway. Instead, a non-cyclic pentose phosphate pathway along with the Krebs cycle is apparently the major route of glucose dissimilation in this organism. Glucose does not support or stimulate the growth of strains of T. neapolitanus, T. thioparus, and T. thiooxidans examined, nor does its presence in the growth medium greatly influence their enzymatic constitution. These obligately chemolithotrophic thiobacilli do not possess the Entner-Doudoroff pathway. Their nicotinamide adenine dinucleotide (NAD)-linked isocitrate dehydrogenase activity predominates over their nicotinamide adenine dinucleotide phosphate (NADP)-linked activity; the converse is true for the other thiobacilli. The data suggest that NAD-linked isocitrate dehydrogenase activity in thiobacilli is involved in biosynthetic reactions. 相似文献
996.
Abdul Q. Siddiqui 《Environmental Biology of Fishes》1979,4(3):257-262
Synopsis
Tilapia zillii breeds all year round in the equatorial Lake Naivasha with slightly high breeding intensity during wet months (March, May
and July–August). A sex ratio of 1 : 1.28 was found between males and females. The smallest mature male and female were 9.0
and 11.0 cm respectively. The fecundity ranged from 2990 to 12344 eggs, with a mean of 6606 eggs. Fecundity showed a curvilinear
relationship with total length (log F = 1.7034 + 1.6370 log L) and a linear relationship with body weight (F = 2197 + 28.76
W) 相似文献
997.
Oestrogen-induced cholesterol and fatty acid biosynthesis in Xenopus laevis liver during vitellogenic response
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Deborah F. Smith Trevor M. Penning Abdul Quadar Ansari Kenneth A. Munday Muhammad Akhtar 《The Biochemical journal》1978,174(2):353-361
1. Oestradiol-17β induces livers of Xenopus laevis (South African clawed toad) to synthesize and secrete into the serum large quantities of the egg-yolk-protein precursor, vitellogenin. The peak of this response occurs 9–16 days after hormone treatment [Dolphin, Ansari, Lazier, Munday & Akhtar (1971) Biochem. J. 124, 751–758]. It is now shown that 6 days after hormone treatment a 120–160-fold stimulation of the synthesis of cholesterol and fatty acid compared with control values occurred. 2. A cell-free system, derived from Xenopus liver, which synthesizes squalene and fatty acid is described. By using this system, several hundredfold stimulation of incorporation of [14C]acetate into squalene was recorded 6 days after the administration of oestradiol-17β, compared with a 3–4-fold stimulation of incorporation of [3H]mevalonate compared with control values. It is argued that oestradiol-17β must affect enzyme(s) catalysing step(s) between acetate and mevalonate in the biosynthetic pathway to cholesterol. 3. In incubation of liver slices in vitro, most of the lipid and cholesterol synthesized in response to the steroid hormone was associated with those subcellular fractions that contained membranes. Moreover, pulse-labelling experiments in vivo showed that 70% of this lipid and cholesterol was retained in the liver. The remainder appeared in the serum, where it was equally distributed between vitellogenin and vitellogenin-free serum. 4. G.l.c. analyses of the cholesterol content of liver microsomal fractions of Xenopus laevis indicated that the cholesterol content was at least 50% higher in microsomal fractions obtained from livers that had been exposed to oestradiol-17β. Meanwhile, g.l.c. analysis of the lipid moiety of secreted vitellogenin showed that up to 35% of its lipid was cholesterol. 相似文献
998.
1. 1.The changes in fatty acid composition of trout liver phosphatidyl-choline, when the environmental temperature was increased, resulted in modifications in the amounts of the different molecular species.
2. 2.In vivo, incorporation of 32P occurred more rapidly in the molecular species with high degree of unsaturation.Temperature acclimation did not modify the relative proportions of label shown in the five subfractions.
3. 3.In vitro incorporation of 14C-methyl-choline also occurred more rapidly in the most unsaturated molecular species. However, when the incubation temperature was raised, the proportion of label decreased in the unsaturated fractions.
999.
1000.
Chromium-resistant bacteria and cyanobacteria: impact on Cr(VI) reduction potential and plant growth
Faisal M Hameed A Hasnain S 《Journal of industrial microbiology & biotechnology》2005,32(11-12):615-621
Two chromium-resistant bacterial strains, Bacillus cereus S-6 and Ochrobactrum intermedium CrT-1, and two cyanobacterial strains, Oscillatoria sp. and Synechocystis sp., were used in this study. At initial chromate concentrations of 300 and 600 microg K2CrO4 mL(-1), and an inoculum size of 9.6 x 10(7) cells mL(-1), B. cereus S-6 completely reduced Cr(VI), while O. intermedium CrT-1 reduced Cr(VI) by 98% and 70%, respectively after 96 h. At 100 microg K2CrO4 mL(-1), Synechocystis sp. MK(S) and Oscillatoria sp. BJ2 reduced 62.1% and 39.9% of Cr(VI), respectively, at 30 degrees C and pH 8. Application of hexavalent chromate salts adversely affected wheat seedling growth and anatomical characters. However, bacterial inoculation alleviated the toxic effects, as reflected by significant improvements in growth as well as anatomical parameters. Cyanobacterial strains also led to some enhancement of various growth parameters in wheat seedlings. 相似文献