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971.
972.
C(4) phosphoenolpyruvate carboxylase (PEPCase: EC 4.1.1.31) is subjected to in vivo regulatory phosphorylation by a light up-regulated, calcium-independent protein kinase. Salt stress greatly enhanced phosphoenolpyruvate carboxylase-kinase (PEPCase-k) activity in leaves of Sorghum. The increase in PEPCase-k anticipated the time course of proline accumulation thereby suggesting that water stress was not involved in the kinase response to salt. Moreover, osmotic stress seemed not to be the main factor implicated, as demonstrated by the lack of effect when water availability was restricted by mannitol. In contrast, LiCl (at a concentration of 10 mM in short-term treatment of both excised leaves and whole plants) mimicked the effects of 172 mM NaCl salt-acclimation, indicating that the rise in PEPCase-k activity resulted primarily from the ionic stress. Both NaCl and LiCl treatments increased the activity of a Ca(2+)-independent, 35 kDa kinase, as demonstrated by an in-gel phosphorylation experiment. Short-term treatment of excised leaves with NaCl or LiCl partially reproduces the effects of whole plant treatments. Finally, salinization also increased PEPCase-k activity and the phosphorylation state of PEPCase in darkened Sorghum leaves. This fact, together with increased malate production during the dark period, suggests a shift towards mixed C(4) and crassulacean acid metabolism types of photosynthesis in response to salt stress. 相似文献
973.
Stereological methods were applied to bovine cumulus-oocyte complexes (COCs) in order to characterize them quantitatively during the estrous cycle. COCs from medium (4-8mm) antral follicles with a compact and complete cumulus mass, and with an uniform or a non-visible ooplasm were aspirated from ovaries of Holstein-Friesian cows, fixed in glutaraldehyde, randomly embedded in glycol-methacrylate, and sectioned at 20 microm. The unbiased nucleator principle was used for estimating the mean volumes of complexes, oocytes, cumulus cells, and nuclei of oocytes and cumulus cells. The thickness of the zona pellucida and the relative numerical percentages of the several morphological types (C1-C3) of cumulus cells were also evaluated. The optical disector procedure was used for cumulus cell sampling. Quantitative data show that COCs appear heterogeneous for all studied parameters. From metestrus to proestrus the volumes of COCs and oocytes remained constant, the volumes of oocytes and oocyte nuclei were correlated, the thickness of the outer zona pellucida decreased, and the relative numerical frequency of follicular type C3 cells increased. Results suggest that COCs from distinct estrus stages are structurally different, with type C3 follicular cells gradually differentiating from cell types C1 and C2. 相似文献
974.
Yoshinari NH Abrão MG Bonoldi VL Soares CO Madruga CR Scofield A Massard CL da Fonseca AH 《Memórias do Instituto Oswaldo Cruz》2003,98(3):311-318
This paper reports a case of coinfection caused by pathogens of Lyme disease and babesiosis in brothers. This was the first case of borreliosis in Brazil, acquired in Cotia County, State of S o Paulo, Brazil. Both children had tick bite history, presented erythema migrans, fever, arthralgia, mialgia, and developed positive serology (ELISA and Western-blotting) directed to Borrelia burgdorferi G 39/40 and Babesia bovis antigens, mainly of IgM class antibodies, suggestive of acute disease. Also, high frequencies of antibodies to B. bovis was observed in a group of 59 Brazilian patients with Lyme borreliosis (25.4%), when compared with that obtained in a normal control group (10.2%) (chi-square = 5.6; p < 0.05). Interestingly, both children presented the highest titers for IgM antibodies directed to both infective diseases, among all patients with Lyme borreliosis. 相似文献
975.
dos Santos CM Jurberg J Galvão C Rocha Dda S Fernandez JI 《Memórias do Instituto Oswaldo Cruz》2003,98(7):939-944
The subfamily Triatominae is actually represented by 137 species distributed among 6 tribes and 19 genera. Within this subfamily, the genus Panstrongylus, Berg 1879, is composed by 13 species widespread in sylvatic, peridomestic, and domestic habitats of Neotropical regions. These species are vectors of Chagas disease and consequently are found associated with its main hosts, such as birds and mammals. Interest in species of this genus has been increasing in the last few years. Reports of several authors indicate these Triatominae to invade and colonize houses, increasing their epidemiological significance. Morphometry was used in this study to investigate correlations among possible closely related species. We measured 224 specimens among 13 species through a set of metric variables of the head. The results indicated that the genus Panstrongylus seems to be homogeneous since 10 of the 14 species were shown to be closely related. 相似文献
976.
Dengue fever is currently the most important arthropod-borne viral disease in Brazil. Mathematical modeling of disease dynamics is a very useful tool for the evaluation of control measures. To be used in decision-making, however, a mathematical model must be carefully parameterized and validated with epidemiological and entomological data. In this work, we developed a simple dengue model to answer three questions: (i) which parameters are worth pursuing in the field in order to develop a dengue transmission model for Brazilian cities; (ii) how vector density spatial heterogeneity influences control efforts; (iii) with a degree of uncertainty, what is the invasion potential of dengue virus type 4 (DEN-4) in Rio de Janeiro city. Our model consists of an expression for the basic reproductive number (R0) that incorporates vector density spatial heterogeneity. To deal with the uncertainty regarding parameter values, we parameterized the model using a priori probability density functions covering a range of plausible values for each parameter. Using the Latin Hypercube Sampling procedure, values for the parameters were generated. We conclude that, even in the presence of vector spatial heterogeneity, the two most important entomological parameters to be estimated in the field are the mortality rate and the extrinsic incubation period. The spatial heterogeneity of the vector population increases the risk of epidemics and makes the control strategies more complex. At last, we conclude that Rio de Janeiro is at risk of a DEN-4 invasion. Finally, we stress the point that epidemiologists, mathematicians, and entomologists need to interact more to find better approaches to the measuring and interpretation of the transmission dynamics of arthropod-borne diseases. 相似文献
977.
Falqueto A Sessa PA Ferreira AL Vieira VP Santos CB Varejão JB Cupolillo E Porrozzi R Carvalho-Paes LE Grimaldi Júnior G 《Memórias do Instituto Oswaldo Cruz》2003,98(8):1003-1010
Between 1985 and 2000, epidemiological surveys of the American tegumentary leishmaniasis (ATL) were carried out in several rural and urban communities in Espírito Santo, Brazil. A total of 100 stocks of Leishmania (comprising isolates from both human and canine hosts with ATL) were identified by two methods of molecular characterization, using specific monoclonal antibodies and multilocus enzyme electrophoresis. Parasite isolates from 19 municipalities were found to belong to the same zymodeme and serodeme type as of the Leishmania (Viannia) braziliensis reference strain. In contrast, our genotyping studies have shown intra-specific variation among these parasites (comparisons of the variability of the internal transcribed spacers between the small and large subunits of the rRNA genes of the 22 stocks studied revealed at least 11 genotypes). Two main clusters of L. (V.) braziliensis genotypes were observed, representing parasites collected from different endemic regions in the state, where transmission reflects distinct eco-epidemiological features. Infection with this pathogen was associated with the characteristic disease forms, but neither the clinical outcome nor the response to treatment could be related to the genetic polymorphism of the isolates, as defined by using the proposed methodology. 相似文献
978.
The infection rates of Babesia sporokinetes in engorged Boophilus microplus were evaluated during a 2-year period in a dairy farm located in an area of enzootic stability. Every 14 days engorged females were collected from calves and from adult animals. Ticks were incubated at 27 +/- 0.5 degree C and 80-90% relative humidity and Babesia infection rates were determined by microscopic examination of Giemsa-stained hemolymph smears. After 52 collections, 2105 ticks were obtained, from which 982 were collected from calves and 1123 from cows. The total Babesia infection rate was 10%, however the incidence was higher (p < 0.05) in ticks collected from calves (17.5%) than in those collected from cows (3.6%). Females collected from cows showed the highest infection rates in January, March, and August, and absence of infection in April and May. Ticks feeding on calves were infected throughout the experimental period. The infection rates of engorged females collected from naturally infected calves that were artificially infested with Babesia-free-larvae of B. microplus gradually decreased until the calves were four months old. No differences were observed among infection rates of ticks collected from calves maintained under natural conditions. 相似文献
979.
The phlebotomine sand flies Nyssomyia intermedia and Nyssomyia neivai are the probable vectors of American tegumentary leishmaniasis in the Southern and Southeastern regions of Brazil. These species form a complex, being difficult to separate between either females or males of the two members based on recognized morphological characteristics. Both N. intermedia and N. neivai are redescribed here in the search for characters that facilitate their correct identification. It was possible to differentiate females by means of spermathecal characteristics. Males could be separated with confidence by the tips of the genital filaments, which have the form of a deep spoon, the angle of the concavity being well accentuated in N. intermedia and much shallower in N. neivai. 相似文献
980.
Bezerra FS Nogueira-Machado JA Martins-Souza RL Chaves MM Correa RF Coelho PM 《Memórias do Instituto Oswaldo Cruz》2003,98(1):73-75
High doses of gamma radiation (10 Krad) in Biomphalaria tenagophila snails (Taim strain), which have been found to be resistant to Schistosoma mansoni, were not sufficient to impair their resistance to the parasite. The number of hemocytes, as well as their phagocytic activity, were not affected by irradiation, thus showing resemblance with mammal macrophages, which are resistant to gamma irradiation also. 相似文献