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81.
I E Gurski? Ts V Serbeniuk P Ia Romanovski? 《Zhurnal evoliutsionno? biokhimii i fiziologii》1988,24(4):545-550
It has been shown that thyroliberin and its synthetic analogue PR-546 injected into the lymphatic sacs (4.10(-7)-4.10(-9) g/kg) or applied to the medulla oblongata in the bulbar frogs (4.10(-10)-4.10(-12) g/kg) significantly increase the rate of motor respiratory volleys in the hypoglossal nerve. In preparations with the irregular level of the activity of the respiratory center, these drugs enhanced stabilization of the initial level of the rhythm of motor respiratory discharges. 相似文献
82.
Summary Two winter wheat genotypes (Diószegi 200 and Mv 15) were compared for their in vitro androgenic capacity. On average, the induction frequency of embryogenic structures was 71.7% in Diószegi 200 and only 4.3% in Mv 15. The haploid induction ability of the two genotypes differed considerably, with Diószegi 200 being much higher. The difference in the in vitro inductability of the microspores may result from genetic differences which are manifested in the survival rate of the microspores during the culture period and their adaptability to in vitro conditions. Special DNA fluorochrornes were suitable for studying the different pathways of in vitro androgenesis. Our data indicate that the repeated equal divisions of the microspore nucleus might lead to pollen embryo formation, and subsequent divisions of the vegetative portion of the pollen grain after the first asymmetric microspore mitosis can result in pollen callus formation. 相似文献
83.
N A Borisova E V Proshliakova A Ia Sapronova M V Ugriumov 《Biulleten' eksperimental'no? biologii i meditsiny》1992,113(6):653-655
With the use of "isotopic method" a study was made of the main parameters of functional activity of serotoninergic elements of hypothalamus--the specific uptake and release of 5-OT. The animals used were sexually mature rats castrated on the first postnatal day. In sexually mature intact males the specific uptake of 3H-5-OT by serotoninergic structures of the anterior hypothalamus was significantly lower than in females. Castration of animals on the first day of life resulted in the increase of specific 5-OT uptake in sexually mature males up to that observed in females. There were no differences between the sexes in the rate of spontaneous release of 5-OT. However, response to K(+)-depolarization in the anterior hypothalamus of intact males was significantly lower than that in females. In the hypothalamus of males castrated neonatally the amplitude of the response to the effect of the depolarizing agent was increase up to the level observed in females. By the results obtained it is indicated that elimination of the effect of male hormones on the first postnatal day results in the increase of 5-OT uptake and release in the hypothalamus of sexually mature rat males. 相似文献
84.
85.
L B Pinchuk Ia I Serkiz N K Rodionova G G Pukhova N A Druzhina G N Koval' A I Lipskaia V N Maslenny? S T Malinari 《Radiobiologiia》1991,31(5):635-641
It has been shown that rats born during the first months after the Chernobyl A.P.S. disaster exhibit essential changes in the peripheral blood and bone marrow haemopoiesis throughout the entire lifetime. Rats brought up in Chernobyl from the age of three months on display even more pronounced changes. It is assumed that the changes in the haemopoiesis develop due to the continuous influence of low-level radiation of different quality and are attributed to the effect of the incorporated radionuclides. 相似文献
86.
Recovery cycles of the auditory brainstem responses were studied in the bottle-nosed dolphin, Tursiops truncatus, using paired acoustic clicks. The recovery time was longer if both clicks had identical spectra (50% recovery at 0.9 ms), as compared with that of different spectra (50% recovery at 0.35 ms). These results can explain a different recovery time of evoked responses after an artificial sound and after own locating one. 相似文献
87.
A Ia Avanov 《Bioorganicheskaia khimiia》1991,17(7):937-944
Theoretical conformational analysis of C-terminal fragments of tachykinin peptides with a common amino acid sequence Asx-Xaa-Phe-Yaa-Gly-Leu-Met-NH2 suggested the conformational states to be independent of the nature of Xaa and Yaa residues. It is shown that among plausible spatial forms of the C-terminal fragments an alpha-helix with the hydrophobic coat consisted of identically oriented side chains is energetically the most stable structure. The preference of this conformation for tachykinins functioning is discussed. 相似文献
88.
I V Smirnov G Ia Tseneva L A Mitrikova 《Molekuliarnaia genetika, mikrobiologiia i virusologiia》1991,(3):19-21
The dispersion of plasmid pYV associated virulence markers in 474 Yersinia strains isolated from people has been studied. The ability to autoagglutination, calcium dependence of growth and the specific antigens were identified in 157 strains of traditionally pathogenic Yersinia enterocolitica serovars 03, 09, Yersinia pseudotuberculosis serovar I. They were not found in 223 strains of other 12 serovars of Yersinia enterocolitica, in 40 strains of Yersinia frederiksenii, Yersinia kristensenii, Yersinia intermedia. The proportion of virulent clones in the population of Yersinia is noted to depend on the conditions of its existence in vivo or in vitro. Identification of virulence markers is acknowledged to be expedient in epidemiological and ethiological estimation of the role of isolated Yersinia strains. 相似文献
89.
The interaction of memory structures and retrieval dynamics is discussed. A mathematical model for associative free recall is presented to support the view that the organization of simple processing units plays an important role in the retrieval of memory traces. Computer simulations show that "flexibility" and "fidelity" of the dynamics strongly depend on the network structure, the amplification and decay parameters, and the noise term. 相似文献
90.