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51.
Summary A new mutation strategy, which involves -irradiation of cells followed by a selective enzymatic enrichment step, was worked out to obtain auxotrophic mutants from the astaxanthin-producing yeast P. rhodozyma. Under the optimized conditions described, different mutants suitable for strain improvement were isolated. 相似文献
52.
M. Pal A. M. Calvo M. C. Terrón A. E. González 《World journal of microbiology & biotechnology》1995,11(5):541-545
The mushroom Flammulina velutipes and the white-rot fungus Trametes versicolor were cultivated separately on sugarcane bagasse for 40 days. Trametes versicolor produced laccase and manganese-peroxidase activities, showing a simultaneous degradation of lignin and holocellulose. However, only phenoloxidase activity was found with Flammulina velutipes. A preferential degradation of lignin was detected in F. velutipes, which exhibited a greater reduction in the ratio of weight loss to lignin loss than T. versicolor. A decrease in the syringyl/guaiacyl ratio observed with both fungi indicated the preferential degradation of non-condensed (syringyl-type) lignin units. An increase in the relative abundance of aromatic carboxylic acids suggested that the oxidative transformation of lignin unit side-chains was occurring. This was more noticeable with Flammulina velutipes than with T. versicolor. 相似文献
53.
54.
Soft, nodular and hard types of calli were initiated on mature zygotic embryo explants of two tetraploid clones of Costus speciosus, of which, only the hard calli were amenable to morphogenetic responses. The two clones differed in their growth regulator requirements both for the initiation of calli and for shoot regeneration. De novo formation of both shoot bud meristems and somatic embryoids were observed. Latter were encased partially or fUlly by coleoptilar sheath. Embryoids could be isolated as discrete units. On maturity, a stock like appendage developed from the base and finally embryoids got detached from the subtending tissue. Both shoot-bud meristems and somatic embryoids developed into complete plantlets, the former upon sequential transfer of calli on Schenk and Hildebrandt’s (SH) basal medium containing lower levels of growth hormones, while the latter only on basal medium. These culture regenerants were subsequently transferred to the field. The morphogenetic behaviour of these two tetraploid clones reflects their marked genotypic difference inspite of their same ploidy status. 相似文献
55.
Ravendra Pal Singh 《Journal of biosciences》1984,6(2):203-212
Rapidly metabolizable compounds such as glucose or glycerol were not utilized byBacillus megaterium in the absence of manganese when grown in the supplemented nutrient broth medium. Under these conditions, growth ceased at
low cell titre, 3-phosphoglyceric acid accumulated inside the cells and normal sporulation process was arrested. Addition
of manganese to the medium caused disappearance of 3-phosphoglyceric acid, growth resumed and normal sporulation was observed.
Synthesis of 3-phosphoglyceric acid occurred only in the mother cell compartments and it was transported for accumulation
inside the forespores ofBacillus megaterium when grown in supplemented nutrient broth medium. Incubation of forespores in the presence of glucose or glycerol had no
effect on 3-phosphoglyceric acid synthesis/accumulation, but it was completely utilized when forespores were incubated with
manganese plus ionophore (X 537A). No other metal(s) could substitute for manganese suggesting that manganese plays crucial
role in 3-phosphoglyceric acid metabolism 相似文献
56.
57.
Fons A.L.J. Peters Ron H.M. Van Der Pal Robert L.A. Peters Wim J. Vredenberg Ruud Kraayenhof 《BBA》1984,766(1):169-178
This work aimed at the resolution of the multi-component electric potential changes induced by single-turnover flash illumination of Photosystem-I-enriched subchloroplast vesicles. If supplemented with ferredoxin and under carefully adjusted redox poising, these vesicles show a pronounced slow-rising and -decaying electric potential component, as monitored by endogenous and exogenous field-sensitive probes, carotenoids and oxonol VI, respectively. The fast and slow potential components can be easily discriminated without the need for computer-assisted deconvolution after selective presaturation of the slow component by preillumination or a transmembrane ΔpH, after selective suppression of the slow component by low valinomycin or uncoupler concentrations or in the absence of ferredoxin. The slow electric potential component, as compared to the fast one, is relatively sensitive to low concentrations of ionophores and uncouplers, detergent, ageing and lower temperatures (4–12°C), is associated with electrogenic proton displacements and is interpreted to respond to a field that is more located on the membrane-bulk interface. Temperature effects show transition temperatures around 20°C for both the rise and decay of the slow potential component. The results provide further evidence that the carotenoids and oxonol VI sense the same (slow) electric field, but may be differently located in the thylakoid membrane. 相似文献
58.
Summary Application of a granular formulation of hexachlorocyclohexane (HCH) to the potted soil at flooding decreased the concentration
of iron and. to some extent, manganese in rice plants, especially at concentrations above 3 ppm active ingredient (a.i.) Likewise,
HCH, applied to rice fields at transplanting (several days after submergence) caused a significant decrease in the concentration
of iron, and not manganese, in the rice plant but only at concentrations above 12.5 kg a.i./ha despite high levels of reduced
iron in the soil. Inhibition of iron reduction by HCH was more pronounced when applied at flooding than at several days after
flooding. 相似文献
59.
Flat bones of human skeleton were subjected to dynamic indentation with ball indenters. The impacted surface was studied under
high magnification and also by using the technique of multiple beam interferometry. The impulse caused the pile up of material
at a little distance from the edge of the indent. The diameter of indent is found to increase as fourth root of the energy
of impact. Bone structure also has the tendency to minimize the damage caused by external forces. There was about 90% recovery
in deformation in the depth of indents due to internal stresses created inside the bone by the impact. 相似文献
60.
Champa Sengupta Vincenzo Deluca David S. Bailey Desh Pal S. Verma 《Plant molecular biology》1981,1(1):19-34
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. 相似文献