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101.
It was found that ethionine partially inhibits the transport of the inducer (TMG) of β-galactosidase into the cells ofEscherichia coli ML-30. The synthesis of β-galactosidase-specific messenger RNA is not inhibited. Ethionine appears to be incorporated into
proteins synthesized by the strains used. The incorporation of ethionine into the molecule of β-galactosidase results in the
synthesis of an enzymically inactive, immunologically cross-reacting protein. 相似文献
102.
Manometric studies were carried out on the respiratory activity of different rhizosphere and non-rhizosphere soils to follow
quantitatively the over-all microbial activity in the rhizosphere soil as affected by the species and growth phase of plant.
Oxygen consumption was distinctly greater in rhizosphere soils as compared to that in non-rhizosphere soils. The difference
between oxygen consumption by rhizosphere and non-rhizosphere soils changed with the course of plant growth and it was not
the same in different plants. This difference in oxygen consumption might be a measure of the amount of available oxidizable
substrate in the rhizosphere. A rhizosphere sample had greater diversity as well as higher concentration of free amino acids
than a non-rhizosphere sample of the same soil. Bacterial counts pointed to preferential stimulation in the rhizosphere of
bacteria requiring individual amino acids. amino acids, such as glycine, alanine, asparsic acid of tyrosine were oxidized
more rapidly in rhizosphere than in non-rhizosphere soil, but the extsent of oxidation for each of the amino acids studied
did not differ. The amount of oxygen consumed during oxidation of alanine, aspartic acid or tyrosine was about one-half of
the total amount necessary for complete oxidation. With glycine a higher extent of oxidation (60%) was observed. These extents
of oxidation of glycine and aspartic acid did not change on investigation at two different phases of plant growth. 相似文献
103.
104.
L. Prokešová 《Folia microbiologica》1969,14(1):82-88
IgM was isolated from pig serum by isoelectric precipitation and gel filtration. Different methods of breaking down the disulphide
bonds and of isolating subunits of the IgM molecule—oxidative sulphitolysis and reduction by 0.1m 2-mercaptoethanol in the absence of a disaggregating agent, oxidative sulphitolysis in the presence of 6m urea and reduction by 0.3m 2-mercaptoethanol in medium containing 6m and 8m urea—were compared. Degraded material was separated by gel filtration on Sephadex G-100 or G-200 in 0.05m formic acid with 6m or 8m urea. Oxidative sulphitolysis or reduction by 0.1m 2-mercaptoethanol without a disaggregating agent did not yield pure H andl chains. Oxidative sulphitolysis was the more effective. Oxidative sulphitolysis in 6m urea medium severely damaged the material. Reduction of IgM by 0.3m 2-mercaptoethanol in 6m or 8m urea also altered its immunochemical properties. The possible presence of light chains in the heavy chain fraction cannot
likewise be excluded in this case. The results are in agreement with experiments showing that the molecular weight of the
IgM heavy chain is greater than that of the IgG heavy chain. 相似文献
105.
The virus origin of a Czechoslovak isolate of potato witches' broom disease is discounted: electron micrographs of ultrathin section of phloem tissues from plants infected with potato witches' broom disease demonstratedMycoplasma-like bodies, spherical or elongated showing binary fission and fragmentation. The minute corpuscles have a diameter of about 50–60 nm, the largest bodies of 1000 nm. The width of elongated filamentous structures is about 200 nm, most oval bodies have a diameter of 250 nm. A weak tetracycline treatment of diseased plants causes a delay of symptom development; a strong dose of tetracycline (applied by means of the wick method into the stem) inhibits symptom appearance completely. Tetracycline produces a phytotoxic effect inhibiting the growth of tomato plants and causing (at higher concentrations) necrosis and death of these plants. There is a note in the paper dealing with the term “mycoplasma”. The word mycoplasma in the sense ofEriksson (1897) or ofMereschkowsky (1910) does not correspond to the genus nameMycoplasma Nowak (1929). 相似文献
106.
Some properties of pea enation mosaic virus isolated from field pea and broad bean plants in Bohemia
Pea enation mosaic virus (PEMV) was isolated from disea sed field pea (Pisum sativum L.ssp. arvense A.Gr.) and broad bean (Faba vulgaris Moench) plants grown as filed crops at Bohumilice in Bohemia. The virus proved to be pathogenic for the following plant species:Pisum sativum L. cv. Raman,Faba vulgaris Moench,Lens culinaris Med.,Vicia sativa L.,Lathyrus odoratus L.,Glycine soja L.,Phaseolus vulgaris L.,Chenopodium amaranticolor Coste andReyn,Nicotiana clevelandi Gray,Trifolium incarnatum L. The dilution end point of the isolate was higher in pea plants (10?4) than in broad bean plants (10?2). The thermal inactivation point was 65–68° and the longevityin vitro between 10 and 14 days. According to the host range, symptoms on pea plants and physical properties the virus isolate studied resembles some isolates described in the U.S.A. and represents a PEMV strain different from those reported so far in Czechoslovakia. 相似文献
107.
Milena Riesová-Kučerová 《Biologia Plantarum》1969,11(5):338-346
The dependence of the frequency of recessive lethal (two groups), chlorophyll and morphological mutations on the mutagen concentration was determined in M2 after subjection to N-nitroso-N-methylurea applied to seeds ofArabidopsis in three concentrations (0·05, 0·10 and 0·20mm). The observed frequencies were compared with the theoretically expected ones for the linear and for two exponential types of dependence, by using the t-test, according to the formulas m=k. C, m=k. C3/2, m=k. C2. No satisfactory agreement with any expected type of dependence was found when directly observed frequencies were used. Since a considerable deficit of mutation frequency was observed in high concentrations, the correction of frequency values was done with respect to the probability of occurence of double mutations. After such a correction, a clear exponential relation was found in both types of lethals and a linear one in chlorophyll and morphological mutations. The probable occurence of multiple mutations should be, therefore, taken into account if the dependence of mutation frequency on the concentration of mutagen is discussed. 相似文献
108.
Summary The occurrence of lysosomes has been investigated electron microscopically and cytochemically in cells of rat liver in the course of ontogenesis.It has been found that primary lysosomes occur during the whole period under investigation and that they originate from the Golgi complex. Some of them assume the appearance of multivesicular bodies. Acid phosphatase activity is lower at the prenatal stage than after the birth. The occurrence of secondary lysosomes proceeds in two stages. Secondary lysosomes appear in a high number at the beginning of differentiation of the liver diverticulum (10–12 day of embryonic life). On the subsequent days they are, with few exceptions, no more present. At the end of the embryonic period (starting with the 20th day) and especially after the birth, they progressively grow in number and move from the region of central cytoplasm peripherally towards the bile capillary.Differences in occurrence of secondary lysosomes are in connexion with reconstruction of the liver primordium at the beginning of liver development and with the change in metabolism of the liver cell after the birth. 相似文献
109.
Hana Marečková 《Archives of microbiology》1969,68(2):113-115
Summary The transformation of streptomycin resistance in Rhizobium japonicum was studied. The susceptible strain 211 was selected from sixty strains and one step mutant resistant to streptomycin in concentration 1 mg per 1 ml was used as the donor. The peak of the competence curve appeared at the ninth hour of growth; the frequency, when the homologous strain had been used was 0.01 p.c. The transformed resistance was of the same level as in the donor strain.This investigation forms part of a contribution prepared by the Czechoslovak National Committee for the International Biological Programme (Section PP: Production Processes). 相似文献
110.
Chromosome counts of some Mongolian plants 总被引:1,自引:0,他引:1
The paper gives the chromosome numbers of 45 species from 72 Mongolian localities, belonging to the genera:Amygdalus, Asparagus, Astragalus, Cancrinia, Caragana, Chamaerhodos, Chelidonium, Chesneya, Dianthus, Hypecoum, Lathyrus, Lilium, Oxytropis, Papaver, Potentilla, Schizonepeta, Sibbaldia, Thermopsis, Trifolium, Trigonella, Vicia. Chromosome morphology of three species ofChamaerhodos and taxonomical remarks on some other species are added. A new combinationSibbaldia sericea (Grubov) Soják is proposed. 相似文献