Characterization of salt stress-enhanced phosphoenolpyruvate carboxylase kinase activity in leaves of <Emphasis Type="Italic">Sorghum</Emphasis><Emphasis Type="Italic">vulgare</Emphasis>: independence from osmotic stress,involvement of ion toxicity and significance of dark phosphorylation

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.     

A stereological study of medium antral follicles during the bovine estrous cycle

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.     

Coexistence of antibodies to tick-borne agents of babesiosis and Lyme borreliosis in patients from Cotia county,State of São Paulo,Brazil

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.     

Morphometric study of the genus Panstrongylus Berg, 1879 (Hemiptera, Reduviidae, Triatominae)

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.     

Uncertainties regarding dengue modeling in Rio de Janeiro, Brazil

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.     

Epidemiological and clinical features of Leishmania (Viannia) braziliensis American cutaneous and mucocutaneous leishmaniasis in the State of Espírito Santo, Brazil

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.     

Infection rate of Babesia spp. sporokinetes in engorged Boophilus microplus from an area of enzootic stability in the State of Minas Gerais, Brazil

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.     

Redescription of Nyssomyia intermedia (Lutz & Neiva, 1912) and Nyssomyia neivai (Pinto, 1926) (Diptera: Psychodidae)

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.     

Systematics of the Lutzomyia species of the verrucarum Theodor group, 1965 (Diptera: Psychodiadae)

The verrucarum group of phlebotomine sand flies includes vectors of Leishmania spp. and Bartonella bacilliformis, and from the perspective of public health is considered as one of the most important groups of neotropical phlebotomine sand flies. Due to marked morphological similarity among species constituting this group, the identification based on conventional taxonomic characters can be difficult. Consequently, the verrucarum group has been the focus of numerous taxonomic comparisons which have included the following methods: chaetotaxy, morphometry, larval spiracular system, chorionic structure, morphology of the genital atrium, cytogenetics, morphological phylogenetics, isoenzymes, random amplified polymorphic DNA, cuticular hydrocarbons, DNA probes, and nuclear and mitochondrial nucleotide sequences. Based on morphological characters of the male terminalia, the verrucarum group has been divided in four series, i.e., verrucarum, serrana, townsendi and pia. Since the revision of the group made by Young and Duncan in 1994, ten new species, principally of Andean origin, have been assigned to 3 of the series verrucarum (L. maranonensis, L. cajamarcensis, L. antioquiensis, L. falcaorum), serrana (L. robusta, L. guilvardae) and pia (L. suapiensis, L. tihuiliensis, L. tocaniensis, L. limafalcaoae). The total number of verrucarum group members is now 40. Explanations for this diversity of species include the isolation of ancestral populations in refugia of humid forest during the quaternary period, the Andean cordilleras as geographical barrier, and the appearance of the Isthmus of Panama. Biology systematics and evolution of the verrucarum group is reviewed with emphasis on the 19 species extant in Colombia.     

Micromechanically based poroelastic modeling of fluid flow in Haversian bone

To explore the hypothesis that load-induced fluid flow in bone is a mechano-transduction mechanism in bone adaptation, unit cell micro-mechanical techniques are used to relate the microstructure of Haversian cortical bone to its effective poroelastic properties. Computational poroelastic models are then applied to compute in vitro Haversian fluid flows in a prismatic specimen of cortical bone during harmonic bending excitations over the frequency range of 10(0) to 10(6) Hz. At each frequency considered, the steady state harmonic response of the poroelastic bone specimen is computed using complex frequency-domain finite element analysis. At the higher frequencies considered, the breakdown of Poisueille flow in Haversian canals is modeled by introduction of a complex fluid viscosity. Peak bone fluid pressures are found to increase linearly with loading frequency in proportion to peak bone stress up to frequencies of approximately 10 kHz. Haversian fluid shear stresses are found to increase linearly with excitation frequency and loading magnitude up until the breakdown of Poisueille flow. Tan delta values associated with the energy dissipated by load-induced fluid flow are also compared with values measured experimentally in a concurrent broadband spectral analysis of bone. The computational models indicate that fluid shear stresses and fluid pressures in the Haversian system could, under physiologically realistic loading, easily reach the level of a few Pascals, which have been shown in other works to elicit cell responses in vitro.