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981.
In erythrocytes recovered from blood of geckoes of the species Pachydactylus turneri collected in Gauteng Province, Republic of South Africa, leishmania zuckemani n. sp. were detected. Giemsa stained erythrocytes contained amastigotes, either single or numerous, in loose assemblies or in a compact rounded oggregates which may condense to become a round basophilic bodies with a central hollow. This new species of Leishmania differs from all previously described species in being almost exclusively parasitic in circulating erythrocytes. Three to seven amastigotes lodged all within one, or divided between several parasitophorous vacuoles were detected at the EM level. The amastigotes demonstrated essentially all the cytological components characteristic of leishmania species known to parasitize mammals. A point which emphasizes an already suggested close affiliation between mammalian and lizard Leishmania.  相似文献   
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Immature ear primordia of maize when cultured on a defined liquid medium grew and differentiated in response to two variables: 1) size of initial explants and 2) concentration of kinetin in the medium. Overall growth of primordia, less than 15 mm at explanting, reached an optimum fresh weight and ear length when kinetin was 10–6m. Ears less than 10 mm, in the presence of kinetin, produced many male spikelets with well-developed stamens in both upper and lower flowers. Ears greater than 15 mm, at explanting, produced only female flowers regardless of the kinetin concentration. Different proportions of male and female and bisexual flowers were produced depending upon the initial size of inflorescences and the concentration of kinetin.  相似文献   
988.
989.
Microelement preparations obtained in the course of processing of flint powder stimulate the biological activity of Bifidobacterium adolescentis 94 BIM, grown on complex and synthetic nutritive media. The composition of the microelement preparations differed in the content of cations and anions. Introduction of the preparations into the cultures of physiologically active or anabiotic forms of bifidobacteria changed the parameters of exponential growth: compared to controls, the cultures were characterized by increased specific growth rate and decreased generation time. In the presence of microelements, the development of populations of bifidobacteria was associated with more pronounced accumulation of metabolic products (acetate, lactate, and ethanol). Introduction of microelement preparations increased the rate of synthesis of the extracellular proteinase (maximum content of the enzyme was observed after 3 h, whereas control cultures attained this level only after 6 h).  相似文献   
990.
Problem of three-dimensional structure of chromatin is reviewed. Data concerning ranged distribution of chromosomes in nucleoplasm are shown. Special attention being paid to the role of nuclear matrix in maintenance of nucleus topology. Possible role of satellite sequences and DNA-binding proteins is discussed.  相似文献   
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