Anthramycin-induced sister-chromatid exchange and caffeine potentiation in the chromosomes of Indian muntjac

Cell-cycle kinetics, sister-chromatid exchange (SCE) and chromosome aberrations have been studied from the skin fibroblasts of the Indian muntjac after treatment with 100 micrograms/ml of caffeine and 0.05 microgram/ml of anthramycin. The cultures were incubated for a period which was sufficient for the completion of two consecutive cell cycles and both the drugs appeared to produce a slight inhibitory effect. When anthramycin-treated cells were however post-treated with caffeine, the cells did not proceed beyond one cycle and exhibited a mitotic block. The SCE frequency in the control and the experiments with caffeine and anthramycin was 8.63, 18.32 and 34.88 per cell respectively. The SCEs were randomly distributed amongst all chromosomes unlike a non-random distribution within the X chromosomes. Caffeine and anthramycin produced only 0.5% and 3.1 cells with chromosome aberrations respectively. Potentiation of chromosome aberrations was observed when the anthramycin-treated cells were post-treated with caffeine. Caffeine potentiation presumably results from an inhibition of the cells to cycle and a failure to repair the effect of the mutagen on DNA.     

Post-translational processing of 7S and 11S components of soybean storage proteins

The synthesis and processing of the major storage proteins in soybean cotyledons was studied both in vivo and in vitro. The and subunits of 7S as well as the 11S proteins are synthesized as higher molecular weight-precursors on membrane-bound polysomes. The initial translation products of the 7S are proteolytically cleaved during translation suggesting the removal of a signal peptide as evidenced by the presence of 2 and 2 peptides immunoreactive with 7S antibody in the in vitro chain completion products of the membrane-bound polysomes. This is followed or accompanied by cotranslational glycosylation, which increases their size equivalent to that of initially-synthesized precursors. In vivo pulse-labelled 7S and products are of slightly higher molecular weights than the immunoprecipitable chain-completion products, indicating further post-translational modifications. A slow post-translational processing during a period of 1.5 to 16 h yields the final 7S and glycoproteins.Acidic and basic subunits of the 11S protein appear to be synthesized from common large molecular weight (60K-59K) precursors. Antibodies to the 11S acidic component recognize both acidic and basic domains in the precursor while those raised against basic subunits appear to be specific for that region only. The processing of the 11S precursor is also very slow and occurs post-translationally. This slow rate of processing, coupled with a temporal difference in the synthesis of 7S and 11S components, suggests a highly coordinated mechanism for synthesis and packaging of these proteins into protein bodies during seed development.     

Size variation polymorphisms of the short arm of human acrocentric chromosomes determined by R-banding by fluorescence using acridine orange (RFA)

Summary One hundred normal Caucasians were studied by the RFA technique to estimate the frequencies of size variation of the short arm of acrocentric chromosomes. Each size variation was classified into one of five levels. The most frequent size level (code) was 3; therefore, this was regarded as the average size. If one excludes the average size, the frequencies of size variation by RFA for chromosome 13, 14, 15, 21, and 22 were 22.5, 19.5, 14.5, 19, and 17% respectively. There was no significant difference for the overall frequencies of size variation between sexes. Furthermore, the RFA technique detects more variation in the size of human acrocentric chromosomes than any other method.     

Influence of carbohydrates on quantitative aspects of growth and embryo formation in wild carrot suspension cultures

The rate of kaurene biosynthesis from mevalonate in a cell-free enzyme preparation from the endosperm of immature seeds of Marah macrocarpus is regulated by adenylate energy charge. The response curve is typical of a biosynthetic energy-utilizing sequence in which the rate of biosynthesis increases sharply as the energy charge is increased above 0.80. ADP proved to be an effective inhibitor of this process. AMP gave no inhibition at concentrations up to 2 mm and orthophosphate gave no inhibition up to 15 mm. Measurement of the pool sizes of intermediates in the sequence showed that the presence of ADP caused an increase in the levels of 5-phosphomevalonate and 5-pyrophosphomevalonate and a decrease in the levels of isopentenyl pyrophosphate and kaurene. These results indicate that pyrophosphomevalonate decarboxylase is the enzyme most subject to regulation by adenylate energy charge. The rate of conversion of isopentenyl pyrophosphate to kaurene and the rate of utilization of mevalonate by mevalonate kinase were not influenced by variations in the adenylate energy charge.     

Characterization of shrinkage cracks in medium black clay soil of madhya pradesh

Summary In a field experiment, the pattern and size of shrinkage cracks were studied under three vegetative covers of wheat crop, grass and cultivated fallow. Both the pattern and size of cracking varied widely. Under wheat crop, the major cracks developed parallel to the rows particularly midway between the two rows of plants. The cracks were few in number and simple in nature. And so was the case under grass where the major cracks developed either in between or around the grass tussocks. However, under cultivated fallow development of too many cracks forming an intricate network showed no definite pattern of cracking. In a soil other than the cultivated fallow, the pattern of cracking appeared to be a function of positioning of the plants rather than of the soil itself.As far as the size of cracks is concerned, the widest and deepest cracks developed under wheat crop and narrowest and shallowest under cultivated fallow. Under grass, the width and depth of the cracks was observed to be intermediate between the two extremes of wheat and cultivated fallow. The size of cracks seemed to depend on the magnitude of water loss from the soil. re]19760713     

Effect of CO2 on short-term human lymphocyte culture in vitro

Summary There was no significant difference in the mitotic indices of the cultures maintained at different CO₂ concentrations, i.e. 0%, 5% and 10%. However, considerable variation was recorded among different individuals. Supported by National Cancer Institute Contract No. 1 CP 43251.     

Inhibition of susceptible water soaking and/or hypersensitive reaction in cotton by exopolysaccharide of avirulentXanthomonas campestris pv.malvacearum

The exopolysaccharide (EPS) of avirulentXanthomonas campestris pv.Malvacearum race-32 did not contain the watersoaking (WS)— inducing factor but contained necrotic reaction (NR)-inducing factor and induced NR on resistant cotton (cv. 101-102B) on which the viable cells of the same avirulent race-32 produced hypersensitive reaction (HR). NR and HR were differentiated on the basis of the induction period required, visible reaction on infiltrated areas, bacterial constituents or metabolite responsible, involvement of host constituent during these reactions and its chemical inhibition. Pre and/or challenge inoculation of EPS of avirulent race-32 (3 mg per infiltration or lesion) in susceptible or resistant cotton cultivars, on pre-and/or post-infiltrated (0–8 h) exponential-phase culture of virulent race-32 inhibited the WS and/or HR of the virulent race in susceptible or resistant cotton.     

Presence of RNA from yeast inhibits the photoreactivation of UV-irradiated DNA by Phr A photolyase from Escherichia coli.

Photoreactivation of UV-irradiated DSNA with phr A photolyase from Escherichia coli was studied in the presence of yeast RNA. Mixing of RNA with UV-irradiated DNA before its treatment with photolyase inhibited the photoreactivation of DNA. Denatured (by sonication) RNA was found to be more effective in blocking photolyase action. Agarose gel electrophoresis experiments suggest that this inhibition of photoreactivation is due to interference in the binding of photolyase with UV-irradiated DNA by yeast RNA.     

Effect of estrogen on angiotensin converting enzyme in immature quail oviduct.

Effect of oestradiol was studied on the angiotensin converting enzyme (ACE)--a component of renin angiotensin system, in oviduct of immature quails of 15 days of age. ACE was studied in whole oviduct, magnum, shell gland and the glandular epithelium of magnum and shell gland. It was found that whole oviduct had a significantly higher level of ACE in control than those treated with exogenous estrogen at three dose levels (200, 400 or 600 micrograms). ACE contents of whole muscle and glandular epithelium did not differ but magnum had higher ACE level than the shell gland. Results are explained on the basis of functional role of oviductal parts.     

Enzymatic synthesis and isolation of thymidine diphosphate-6-deoxy-D-xylo-4-hexulose and thymidine diphosphate-L-rhamnose. Production using cloned gene products and separation by HPLC.

A two-step enzymatic synthesis of dTDP-L-rhamnose is developed using enzymes from sonicated extracts of cultures of Escherichia coli K12 strains harboring plasmids containing different parts of the rfb gene cluster of Salmonella enterica LT2. The intermediate dTDP-6-deoxy-D-xylo-4-hexulose was isolated after a 1-h reaction, using only dTDP-D-glucose and dTDP-D-glucose 4,6-dehydratase, followed by protein precipitation and desalting by gel chromatography (yield 89%). In a two-step reaction using dTDP-D-glucose and dTDP-D-glucose 4,6-dehydratase in the first step, and with NADPH, dTDP-6-deoxy-D-xylo-4-hexulose 3,5-epimerase and NADPH:dTDP-6-deoxy-L-lyxo-4-hexulose-4-reductase in the second hour of incubation, the dTDP-D-glucose was fully converted to dTDP-L-rhamnose. The hexoses of both products were identified by mass spectroscopy. The molar yield of dTDP-L-rhamnose, after protein precipitation, anion-exchange chromatography and desalting by gel chromatography, was 62%, corresponding to more than 150 mg, starting from 250 mg of dTDP-D-glucose. When stored lyophilysed under nitrogen, these products were found to be stable for several months. Both dTDP-6-deoxy-D-xylo-4-hexulose and dTDP-L-rhamnose have light absorption maxima at 267 nm, with molar absorption coefficients close to that of dTMP. However, the absorption coefficient of dTDP-6-deoxy-D-xylo-4-hexulose at the absorption maximum of 320 nm (specific for sugars containing keto groups) was found to be approximately 20% higher than values presented earlier. Furthermore, an HPLC technique is presented for determining the net activity of dTDP-6-deoxy-D-xylo-4-hexulose 3,5-epimerase and NADPH:dTDP-6-deoxy-L-lyxo-4-hexulose-4-reductase, based on separation of dTDP-6-deoxy-D-xylo-4-hexulose and dTDP-L-rhamnose. The HPLC technique is also suitable for determination of all the nucleotide components involved in the synthesis.