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31.
32.
The coenzyme-independent dihydroorotate dehydrogenase (EC 1.3.3.1) linking the pyrimidine biosynthetic pathway to the respiratory
chain, was ultracytochemically localized by the tetrazolium method in derepressed exponential-phase cultures ofSaccharomyces cerevisiae. Biochemical analysis showed a considerable variation of this enzyme activity in inverse proportion to the aeration of the
yeast cultures. The assay also showed that after prefixation of yeast cells with 1% glutaraldehyde at 0°C for 20 min, approximately
one-half of the enzyme activity was preserved. The cytochemical reaction mixture contained dihydroorotate (2 mmol/L), thiocarbamyl
nitroblue tetrazolium (0.44 mmol/L), phenazine methosulfate (0.16 mmol/L) and KCN (1.7 mmol/L) in Tris-HCl buffer (100 mmol/L)
of pH 8.0. The osmicated formazan deposits featured envelopes of mitochondria and of nuclei and were prominent in the mitochondrial
inclusions and in the vacuolar membranes. The latter sites of dihydroorotate dehydrogenase activity represent biosynthetic
activity in yeast vacuoles, still generally assumed to function as yeast lysosomes and storage organelles. In the light of
the generally observed invasions of juvenile yeast vacuoles into mitochondria, the enzymic sites observed in mitochondrial
inclusion were considered as evidence of the interactions of yeast vacuoles and mitochondria. Transfer of vacuolar membranes
with dihydroorotate dehydrogenase activity into mitochondrial matrix is suggested. 相似文献
33.
Jan Raška Kateřina Chalušová Jan Krajiček Radomír Čabala Zuzana Bosáková Pavel Štys Alice Exnerová 《Journal of evolutionary biology》2023,36(7):1050-1064
Many prey species change their antipredator defence during ontogeny, which may be connected to different potential predators over the life cycle of the prey. To test this hypothesis, we compared reactions of two predator taxa – spiders and birds – to larvae and adults of two invasive true bug species, Oxycarenus hyalinipennis and Oxycarenus lavaterae (Heteroptera: Oxycarenidae) with life-stage-specific chemical defence mechanisms. The reactions to larvae and adults of both true bug species strikingly differed between the two predator taxa. The spiders were deterred by the defences of adult bugs, but the larval defences were ineffective against them. By contrast, birds attacked the larvae considerably less often than the adult bugs. The results indicate a predator-specific ontogenetic change in defence effectiveness of both Oxycarenus species. The change in defence is likely linked to the life-stage-specific composition of secretions in both species: whereas secretions of larvae are dominated by unsaturated aldehydes, secretions of adults are rich in terpenoids, which probably serve dual function of defensive chemicals and pheromones. Our results highlight the variation in defence between different life stages and the importance of testing responses of different types of predators. 相似文献
34.
In commercial digested and purified horse diphtheria antitoxin, which is formed largely of the gamma globulin fragment with the sedimentation coefficient 5.3 S, the reactive disulphide bonds were destroyed by S-sulphonation. Gel filtration on Sephadex G-100 in 0.05 M formic acid with 6 M urea showed that the molecule of the S-sulphonated preparation dissociated into chains similar in character to the peptide chains of native horse antitoxins. Antibody activity was still partly maintained even after treatment with 6 M urea. On mixing the two types of chains isolated by gel filtration, antibody activity was recovered, the amount of antibody protein determined in the mixed fractions being greater than the sum of the amounts in the separate fractions. The neutralizing activity of the mixed fractions tested against toxinin vivo was also greater than the sum of the activity of the separate fractions. 相似文献
35.
L. Dugovičová L. Fojtík V. Novak Z. Gálová Z. Gálová M. Lejko I. Michalík J. Honza J. Minář J. Zehnálek A. Kostrej I. Kousalová M. Kováčová M. Lexa D. Miklovič M. Kováčová L. Nátr Z. Nátrová V. Novák Y. Kumar M. Novotná F. Plhák E. Tománková J. Zehnálek J. Černohorská M. Dvořák D. Harmancová 《Biologia Plantarum》1992,34(1):555
36.
Structural evolution of wheat chromosomes 4A, 5A,and 7B and its impact on recombination 总被引:3,自引:3,他引:0
K. M. Devos J. Dubcovsky J. Dvořák C. N. Chinoy M. D. Gale 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1995,91(2):282-288
The construction of comparative genetic maps of chromosomes 4Am and 5Am of Triticum monococcum and chromosomes of homoeologous groups 4, 5 and 7 of T. aestivum has provided insight into the evolution of these chromosomes. The structures of chromosomes 4A, 5A and 7B of modern-day hexaploid bread wheat can be explained by a 4AL/5AL translocation that occurred at the diploid level and is present both in T. monococcum and T. aestivum. Three further rearrangements, a 4AL/7BS translocation, a pericentric inversion and a paracentric inversion, have taken place in the tetraploid progenitor of hexaploid wheat. These structural rearrangements and the evolution of chromosomes 4A, 5A and 7B of bread wheat are discussed. The presence of the 4AL/5AL translocation in several Triticeae genomes raises two questions — which state is the more primitive, and is the translocation of mono- or poly-phylogenetic origin? The rearrangements that have occurred in chromosome 4A resulted in segments of both arms having different positions relative to the telomere, compared to 4Am and to 4B and 4D. Comparisons of map length in these regions indicate that genetic length is a function of distance from the telomere, with the distal regions showing the highest recombination. 相似文献
37.
Summary The presence of 1% agar in the fixation and substrate solutions for the histochemical demonstration of thiamine pyrophosphatase (4.4 mM TPP; 3.6 mM Pb2+; 0.025 Tris-maleate buffer, pH 7.2) clearly facilitates the localization of the enzyme in Golgi apparatus in cold microtome sections prepared from unfixed specimens. 相似文献
38.
39.
40.
M. Podojil M. Blumauerová V. Přikrylová Z. Vaněk G. F. Gauze T. S. Maksimova 《Folia microbiologica》1980,25(6):464-466
The strainStreptomyces griseoruber 4620 produces, besides the anthracycline antibiotics beromycins, some other anthracyclines of the rhodomycin type. Twelve
isolates exhibiting a higher antibiotic activity (up to 2.5×), as compared to the parent strain, were obtained after a spontaneous
selection. The following species were isolated from the hydrolysate of mycelial extract: β-rhodomycinone, β-isorhodomycinone,
α2-rhodomycinone and 10-deoxy-β-rhodomycinone, which has not yet been described. 相似文献