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21.
A A Sukhopiatkina O S Bat A V Levitskaia V G Potapova 《Zhurnal mikrobiologii, epidemiologii, i immunobiologii》1985,(4):80-81
The study of the specific epidemiological and clinical features of Q fever revealed the existence of an active focus of infection among humans due to their contacts with agricultural animals in one of the districts of the region. The focus was manifested by group morbidity among the cattle-tending personnel of a dairy farm. The source of this infection was cattle. The infection was transferred mainly through the air. The disease took a moderately severe course. The study of the rickettsial contamination of humans, animals and ticks suggested the presence of the active epidemic process and made it possible to work out concrete antiepidemic measures. 相似文献
22.
23.
F F Dias M K Shaikh Y B Bhatt D C Modi V R Subramanyam 《The Journal of applied bacteriology》1986,60(4):271-275
Mutants of Bacillus amyloliquefaciens resistant to at least 10 micrograms/ml of tunicamycin were isolated and shown to be pleiotropic. The mutants were more resistant to streptomycin, chloramphenicol, kanamycin and neomycin than was the parent strain but less resistant to penicillin G and tetracycline. They were more autolytic, presumably due to an altered cell wall. The mutants produced reduced levels of amylase, penicillinase and both metal and serine protease besides having an enhanced sporulation frequency and being more motile. 相似文献
24.
I.D. Algranati 《Biochemical and biophysical research communications》1980,96(1):54-60
Polypeptide synthesis programmed by poly(U) and globin mRNA has been studied in cell-free extracts from wheat germ. A two-step reaction with a preincubation at high Mg++ levels followed by a second step carried out after a shift to a low Mg++ concentration and the addition of labeled amino acids is described. Under these conditions the initiation of polyphenylalanine synthesis can be blocked without affecting the elongation of polypeptide chains. This procedure allows the selective inhibition of polypeptide synthesis initiation without using any drug or antibiotic. 相似文献
25.
V A Berezin E N Zhmarev I A Brodskaia G M Shevchenko L S Zashko 《Biulleten' eksperimental'no? biologii i meditsiny》1985,100(7):68-70
The content of neurospecific proteins S-100, GFA and D2 was measured in malignant cerebral tumors by electrophoresis with the use of monospecific antisera. Concomitant measurement of proteins S-100 and GFA is a more reliable diagnostic criterion as to the tumor histogenesis than study of each protein alone. D2 protein appeared to be the most stable specific marker. 相似文献
26.
I T Norton D M Goodall S A Frangou E R Morris D A Rees 《Journal of molecular biology》1984,175(3):371-394
The thermally induced order-disorder transition of xanthan (extracellular bacterial polysaccharide from Xanthomonas campestris) has been investigated by optical rotation, differential scanning calorimetry, stopped-flow reaction kinetics and low-angle laser light scattering, and the results have been analysed in terms of Zimm -Bragg helix-coil transition theory. The reciprocal of the transition midpoint temperature (Tm) varies linearly with the logarithm of cation (K+) the salt dependence of Tm, is in agreement with Manning polyelectrolyte theory the ordered structure. The associated increase in cation binding, calculated from the salt dependence of tm, is in agreement with the Manning polyelectrolyte theory for one of the candidate structures from X-ray diffraction, a 5(1) single helix stabilized by packing of side-chains along the polymer backbone, but not for the alternative double-helix structure that has also been proposed. At each salt concentration, the two fundamental parameters of the Zimm -Bragg theory, s and sigma, were calculated. The equilibrium constant for growth of the ordered structure (s) is derived directly from calorimetric measurement of transition enthalpy (delta Hcal ), and sigma, which quantifies the relative instability of the helix nucleus, is derived from the ratio of delta Hcal to the apparent transition enthalpy (delta Happ ) obtained by van't Hoff analysis of the optical rotation data. The temperature course of conformational ordering calculated theoretically is in good quantitative agreement with experimental results from both optical rotation and scanning calorimetry. The calculated average length of stable, ordered chain-sequences increases with decreasing temperature, but equals or exceeds the total chain length from light scattering only at temperatures more than approximately equal to 70 K below Tm, suggesting that ordered and disordered regions may co-exist within the same xanthan molecule. Consistent with this interpretation, the observed rate of conformational ordering increases sharply under conditions where the starting solution for dynamic measurements is partially ordered, suggesting that ordered sequences within each chain may act as helix nuclei for adjacent disordered regions, so that helix growth, rather than the slower nucleation process, becomes rate limiting. 相似文献
27.
All plant cells are provided with the necessary rigidity to withstand the turgor by an exterior cell wall. This wall is composed
of long crystalline cellulose microfibrils embedded in a matrix of other polysaccharides. The cellulose microfibrils are deposited
by mobile membrane bound protein complexes in remarkably ordered lamellar textures. The mechanism by which these ordered textures
arise, however, is still under debate. The geometrical model for cell wall deposition proposed by Emons and Mulder (Proc.
Natl. Acad. Sci. 95, 7215–7219, 1998) provides a detailed approach to the case of cell wall deposition in non-growing cells, where there is no evidence for the
direct influence of other cellular components such as microtubules. The model successfully reproduces even the so-called helicoidal
wall; the most intricate texture observed. However, a number of simplifying assumptions were made in the original calculations.
The present work addresses the issue of the robustness of the model to relaxation of these assumptions, by considering whether
the helicoidal solutions survive when three aspects of the model are varied. These are: (i) the shape of the insertion domain,
(ii) the distribution of lifetimes of individual CSCs, and (iii) fluctuations and overcrowding. Although details of the solutions
do change, we find that in all cases the overall character of the helicoidal solutions is preserved. 相似文献
28.
Hostile intercommunity relations, including attacking and killing extra-community infants of both sexes have occurred at most
wild chimpanzee sites. We describe three recent cases of intercommunity attacks on infants committed by members of the Ngogo
chimpanzee community in Kibale National Park, Uganda. Two of the attacks resulted in confirmed infanticides while a third
attack probably resulted in the infant's death. In common with previous accounts of chimpanzee infanticides, the attacks described
here occurred during boundary patrols outside the Ngogo community's usual range, adult and adolescent males were the main
participants, one infant was cannibalized after being killed, and the victims’ mothers did not accompany the attacking party
back to the Ngogo range. However, the patrol parties during each infanticide were larger than before and included females
from the Ngogo community. Our observations indirectly support both the range expansion and imbalance of power hypotheses,
which address why and under which conditions chimpanzee intercommunity encounters lead to aggression. These cases of intercommunity
infanticide add to the growing database of the phenomenon in wild chimpanzees. 相似文献
29.
30.