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71.
Radheshyam K. Jayaswal Ray A. Bressan Denys J. Charles Avtar K. Handa 《FEMS microbiology letters》1986,35(2-3):307-312
Abstract Inc-P plasmids, RP4, R751, pMO850, and pRK2013 were transferred to Erwinia carotovora . These plasmids were stably maintained in E. carotovora and the transconjugants were efficient donors of respective plasmids to other strains of E. carotovora and Escherichia coli . These plasmids were not able to mobilize chromosomal markers from one strain of E. carotovora to another strain of E. carotovora even in the presence of homologous DNA sequences on the plasmid and the bacterial chromosome. The presence of Inc-P plasmid does not affect the pathogenic phenotype of E. carotovora . A broad host range Inc-P cosmid, pLAFR1, was transferred to E. carotovora with the help of pRK2013, suggesting the potential use of a binary plasmid system for genetic complementation in E. carotovora . 相似文献
72.
Nitrogen Source Regulates Glutamate Dehydrogenase NADP Synthesis in Neurospora crassa 总被引:8,自引:4,他引:4
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Georgina Hernndez Ray Snchez-Pescador Rafael Palacios Jaime Mora 《Journal of bacteriology》1983,154(1):524-528
Neurospora crassa glutamate dehydrogenase-NADP (EC 1.3.1.3) has a higher activity when mycelium is grown on ammonium or nitrate as nitrogen source than when grown on glutamate or glutamine. Quantitative immunoelectrophoresis established that, under all conditions, enzyme activity corresponded to enzyme concentration. Isotope incorporation studies demonstrated that the nitrogen source exerts its regulation at the level of de novo enzyme synthesis. 相似文献
73.
Phytohemagglutinin (PHA)-stimulated lymphocytes were cultured in media containing varying levels of K+, Mg2+, Ca2+. Cell activation was monitored by measuring nuclear diameter and by evaluating the area of nucleolus which reacted with silver nitrate. Decreasing extracellular K+ from normal levels (5.0 mM) to 14% (0.7 mM) and decreasing extracellular Mg2+ from normal levels (1.0 mM) to 14% (0.14 mM) did not affect nuclear diameter or silver nitrate reactivity of PHA-stimulated lymphocytes. Chelation of extracellular Ca2+ with EGTA during the first 24 h after PHA stimulation completely inhibited the increases in silver reactivity and nuclear diameter associated with stimulation. Chelation of extracellular Ca2+ 48 h after PHA stimulation did not inhibit lymphocyte stimulation. Inhibitory effects of EGTA were completely reversed if CaCl2 was added to the medium within 24 h of PHA stimulation. By 48 h the effects were irreversible. 相似文献
74.
The effect of two known mutagens on different human tissues was examined in an attempt to determine if tissue specific responses exist in SCE distribution on chromosome. The tissues included human lymphocytes, skin fibroblasts, ovarian and testicular cells. All cell types were exposed to varying concentrations of 5-bromodeoxyuridine (BrdU), and mitomycin C (MMC). The numbers of SCEs were recorded from each tissue. Results indicated that certain of the tissues tested appeared more sensitive to particular agents. Results also showed that in all the tissues tested the larger chromosomes in groups A to C had greater numbers of SCEs than did the smaller chromosomes in groups D to G. There were very few SCEs in F and G group chromosomes including Y. 相似文献
75.
Akhil G. Jhingran R.C. Gupta Suprabhat Ray A.K. Agarwal M.M. Singh Nitya Anand 《Steroids》1983,42(6):627-634
The syntheses of (±) 2α,6β-diethyl-7α-ethynyl-3α-(-hydroxyphenyl)--bicyclo[4.3.0]nonan-7β-ol (), (±)2β,6β-diethyl-7α-ethynyl-3β-(-methoxyphenyl)--bicyclo[4.3.0]nonan-7β-ol () and (±) 2α,6β-diethyl-7α-ethynyl-3β-(-hydroxyphenyl)--bicyclo[4.3.0]nonan-7β-ol () and their derivatives, which are essentially B-seco-steroids having and geometries have been carried out. A study of their antiimplantation activities (AI) and receptor binding affinities (RBA) show that compounds are biologically most potent, followed by the corresponding and compounds. The most potent compound is active at 1 mg/kg in rats. Introduction of 7α-ethynyl group increases their AI activity; however, no significant effect on their RBA is observed. 相似文献
76.
Regulation of leaf senescence, grain-filling and yield of rice by kinetin and abscisic acid 总被引:3,自引:0,他引:3
Senescence of rice ( Oryza sativa L. cv. Jaya) leaves was regulated with kinetin and abscisic acid (ABA) sprays at the reproductive stage. The effect of such sprays on grain-filling and yield was analyzed. Spraying 100-day-old plants with kinetin solution (100 μg ml-1 ) significantly delayed senescence as indicated by higher total chlorophyll and protein levels in the three uppermost leaves compared with the controls. In contrast, spraying with ABA (15 μg ml-1 ) significantly promoted foliar senescence. The number of spikelets per panicle, number of panicles, percentage filled grains, panicle weight and grain yield per plant and the mobilization and harvest indices were significantly increased by kinetin treatment, while ABA decreased most of them. The possibility of increased grain-filling and thus, yield due to delayed foliar senescence by kinetin treatment and decreased grain-filling due to hastening of senescence by ABA is discussed. 相似文献
77.
78.
Demographic data collected for a tribal population of India, the Koyas of Koraput District, Orissa, were examined in light of 2 models of reproductive behavior associated with the economic value of children: the replacement effect and son survivorship motivation. Both models are united in the concept that infant/child mortality affects subsequent fertility. The database consists of retrospective fertility histories of Koya women who had completed their reproductive period. The total number was 260, with the total offspring numbering 1407. 2 distinct cohorts of women were formed for the purpose of analysis, separated only by the criterion of offspring survival: women who had experienced infant child mortality (129 women with 739 children); and women who completed their reproductive period without suffering offspring loss of this nature (132 women with 668 children). The cohort without child loss had a mean parity of 5.10, lower than the average parity of 5.73 recorded for the cohort whose reproductive histories included at least 1 infant/child death. Age specific marital fertility and birth interval analyses indicated that this differential was because of biological, not behavioral, factors. The age pattern of fertility of females suffering offspring mortality failed to demonstrate a high rate of childbearing in the later age intervals of the reproductive period, a characteristic pattern of couples attempting to "replace" lost offspring. Birth interval analysis pointed to biological "interval effect," whereby infant/child mortality caused a cessation of lactation and hence a shortening of postpartum amenorrhea. Computer simulation further indicated that the higher fertility differential of the cohort experiencing offspring loss still did not result in high son survivorship values. The findings agree with earlier studies indicating that for predemographic transitional populations, economically motivated fertility strategies are ineffectual. 相似文献
79.
K.A. Williams D.O.F. Skibinski Ray Gibson 《Journal of experimental marine biology and ecology》1983,66(3):207-211
Starch-gel electrophoresis was employed to compare six enzymes in three closely related species of nemertean worms, Lineus ruber (Müller, 1774), Lineus sanguineus (Rathke, 1799), and Linens viridis (Müller, 1774). Differences in mobility recorded for most of the enzyme loci examined support the hypothesis that these nemerteans are distinct taxa. 相似文献
80.
Otto D. Hensens Ray S. Dewey Jerrold M. Liesch Mary A. Napier Robert A. Reamer Jack L. Smith Georg Albers-Schönberg Irving H. Goldberg 《Biochemical and biophysical research communications》1983,113(2):538-547
Spectroscopic evidence suggests the presence of a highly strained ether ring (Fig. 1) (possibly an epoxide) in the C12-subunit of the previously determined partial structure (Fig. 2) of the major neocarzinostatin chromophore (NCS-Chrom ) which completes assignment of all the oxygens in the molecule. The main product from mercaptan treatment suggests opening of the ether ring involving the addition of one molecule of mercaptan as well as reduction of the C12-substructure, whereas a parallel two-step reduction occurs on NaBH4 treatment. Both reactions occur with rearrangement of the C12-substructure and the implication for the mechanism of action of NCS-Chrom in DNA strand scission activity is discussed. The evidence suggests a downward revision of the molecular formula for NCS-Chrom as well as minor components and by two protons. 相似文献