Parasitoid associated with Liriomyza huidobrensis (Diptera: Agromyzidae) outbreaks in tomato fields in Brazil

1. The knowledge of natural factors that affect pest populations is essential in predicting the occurrence of pest outbreaks and in developing integrated pest management programmes. Natural enemies, climatic elements and host plants are among the most important factors affecting pest dynamics.
2. Tomato (Solanum lycopersicum) is the second most consumed vegetable worldwide. The pea leaf miner Liriomyza huidobrensis (Diptera: Agromyzidae) is a major pest to the tomato in Brazil.
3. This study aimed to determine the main natural factors that regulate L. huidobrensis populations in tomato fields in Brazil.
4. Liriomyza huidobrensis densities were evaluated by directly counting the number of active mines on the basal leaf of the middle section of the plant canopy, and predators and parasitoids were assessed using the leaf‐beating‐against‐a‐tray technique. Eight commercial tomato fields were assessed over two years. The phenological growth stages of the tomato plants (vegetative and reproductive) were noted during the assessments.
5. Liriomyza huidobrensis populations peaked between the middle and end of the planting season.
6. Opius sp. (Hymenoptera: Braconidae) was the main natural enemy of L. huidobrensis.
7. Our results suggest that phenological growth stage and Opius sp. are associated with population dynamics of L. huidobrensis in tomato fields.
8. Therefore, integrated pest management programmes should aim to preserve populations of the parasitoid Opius sp.

     

Virological study of a dengue type 1 epidemic at Rio de Janeiro

A dengue outbreak started in March, 1986 in Rio de Janeiro and spread very rapidly to other parts of the country. The great majority of cases presented classical dengue fever but there was one fatal case, confirmed by virus isolation. Dengue type 1 strains were isolated from patients and vectors (Aedes aegypti) in the area by cultivation in A. albopictus C6/36 cell line. The cytopathic effect (CPE) was studied by electron microscopy. An IgM capture test (MAC-ELISA) was applied with clear and reproducible results for diagnosis and evaluation of virus circulation; IgM antibodies appeared soon after start of clinical disease, and persisted for about 90 days in most patients. The test was type-specific in about 50% of the patients but high levels of heterologous response for type 3 were observed. An overall isolation rate of 46.8% (813 virus strains out of 1734 specimens) was recorded. The IgM test increased the number of confirmed cases to 58.2% (1479 out of 2451 suspected cases). The importance of laboratory diagnosis in all regions where the vectors are present is emphasized.     

Comparative analysis of bacterioplankton assemblages from maritime Antarctic freshwater lakes with contrasting trophic status

The bacterioplankton assemblages of eight maritime Antarctic lakes with a wide range of trophic status and geographic span (six lakes from Hope Bay, Antarctic Peninsula and two from Potter Peninsula, King George Island) were described using denaturing gradient gel electrophoresis and band sequencing during two consecutive austral summers (2003–2004). Analyses of the gels identified a total of 230 bands spread across 57 different positions. Among those bands, 14 were shared between lakes from Hope Bay and Potter Peninsula, 17 were observed only in particular lakes, and 17 were registered both years in the same lake. We successfully reamplified and sequenced 43 bands located in 36 different positions belonging to Bacteroidetes, Actinobacteria, Betaproteobacteria and Cyanobacteria. The closest matches for 63% of the sequenced bands were from Antarctic or from other cold environment clones and sequences already in the databases, suggesting the widespread dominance of microbial communities adapted to cold habitats. The results of the multivariate analyses (Cluster Analysis and CCA) indicated that the nutrient status of the lake influences the bacterioplankton assemblages. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Positive end-expiratory pressure prevents lung mechanical stress caused by recruitment/derecruitment.

This study tests the hypotheses that a recruitment maneuver per se yields and/or intensifies lung mechanical stress. Recruitment maneuver was applied to a model of paraquat-induced acute lung injury (ALI) and to healthy rats with (ATEL) or without (CTRL) previous atelectasis. Recruitment was done by using 40-cmH(2)O continuous positive airway pressure for 40 s. Rats were, then, ventilated for 1 h at zero end-expiratory pressure (ZEEP) or positive end-expiratory pressure (PEEP; 5 cmH(2)O). Atelectasis was generated by inflating a sphygmomanometer around the thorax. Additional groups did not undergo recruitment but were ventilated for 1 h under ZEEP. Lung resistive and viscoelastic pressures and static elastance were computed before and immediately after recruitment, and at the end of 1 h of ventilation. Lungs were prepared for histology. Type III procollagen (PCIII) mRNA expression in lung tissue was analyzed by RT-PCR. Lung mechanics improved after recruitment in the CTRL and ALI groups. One hour of ventilation at ZEEP increased alveolar collapse, static elastance, and lung resistive and viscoelastic pressures. Alveolar collapse was similar in ATEL and ALI, and recruitment opened the alveoli in both groups. ALI showed higher PCIII expression than ATEL or CTRL groups. One hour of ventilation at ZEEP did not increase PCIII expression but augmented it significantly in the three groups when applied after recruitment. However, PEEP ventilation after recruitment avoided any increment in PCIII expression in all groups. In conclusion, recruitment followed by ZEEP was more deleterious in ALI than in mechanical ATEL, although ZEEP alone did not elevate PCIII expression. Ventilation with 5-cmH(2)O PEEP prevented derecruitment and aborted the increase in PCIII expression.     

Mutagenicity and antimutagenicity of <Emphasis Type="Italic">Croton cajucara</Emphasis>

Croton cajucara Benth. (‘sacaca’) is a tree of the Euphorbiaceae family, native to the Amazon region in northern Brazil, where it is widely used in the popular treatment of various diseases. Its active principle, the terpenoid trans-dehydrocrotonin, has been credited with a variety of medical properties, including antiulcer, antiinflammatory, antitumor, antimutagenic and hypoglycemic activity. In this investigation, possible mutagenic and antimutagenic effects were evaluated in treatments using methanol extract of this plant on Swiss Albino mice by examining their peripheral blood cells for micronuclei. In these tests, the material obtained by methanol extraction of C. cajucara tree bark was administered to the mice by gavage. None of the doses evaluated in this study presented mutagenicity. Analysis of the results obtained from studies evaluating antimutagenicity revealed protection against the chemotherapeutic agent cyclophosphamide for the two highest doses used.     

Influence of the incorporation of cholesterol on the doubling time and on the arrhenius and hill plots of two membrane-bound enzymes ofEscherichia coli K12

Escherichia coli was grown at 37°C with increasing cholesterol concentrations in the growth medium. Under these conditions, it was shown that neither the phospholipid species nor the fatty acid composition were affected by the incorporation of cholesterol. On the other hand, the doubling time (t_d) was increased; two membrane-bound enzymes, (Ca⁺⁺)-ATPase and D-lactate-dehydrogenase, were modified in the temperature-dependence activities, and the (Ca^±±)-ATPase changed its Hill coefficient for the inhibition by Na⁺. This last parameter was the most sensitive in detecting very low cholesterol incorporations to the cytoplasmic membranes.     

Allosteric transitions and membrane-bound ATPase from rat tissues: The effect of fat deprivation on the allosteric inhibition by fluoride

In rats red a fat-sufficient diet, ATPases (ATP phosphohydrolase, EC 3.6.1.3) from heart, kidney and brain microsomes showed allosteric kinetics for the inhibition by F^?, with values ofn = ?2.0. In rats fed a far-free diet, the values ofn for the ATPases changed from ?2.0 to ?1.0 in heart and kidney microsomes. When these animals were then fed a fat-sufficient diet the values ofn reached the control values. In brain microsomal ATPases no modification of the values ofn were found between both groups of animals. The regulatory properties of the membrane on bound ATPases are discussed.     

Emotional distress and its socio-political correlates in Salvadoran refugees: Analysis of a clinical sample

The emotional distress responses of refugees cannot be adequately understood using the traditional notions of stress and adaptation. In these populations it is necessary to consider the relations between emotional distress and socio-political context, particularly the processes of terror and intimidation and the conditions of migratory illegality and social marginality.This study analyses the patterns of emotional distress in a clinical sample of 71 Salvadoran refugees in an urban center of the United States. Case histories are presented and patterns of trauma, distress and associated life problems analyzed. It is argued that distress patterns reflect the particular socio-political conditions of women and men and represent the embodiment of the conflicts that refugees face. The concept of illness is used to link distress patterns and socio-political context and to avoid the reductionism of psychiatric categories.     

The convenience of the use of allosteric "probes" for the study of lipid--protein interactions in biological membranes: thermodynamic considerations.

One of the most commonly used methods to study enzyme (protein)-structure interactions at a more specific level is the use of the Arrhenius plots to detect the influence of the “environment” on the enzyme. We want to point out here that the use of a suitable “allosteric enzyme” would be a more sensitive method to detect influences of the environment than the study of Arrhenius plots. According to simple thermodynamic considerations, a change of more than 2.8 kcal/mol in the interaction between enzyme and membrane would be needed to give a noticeable change in the position of the break (T_i) of the corresponding Arrhenius plot. On the other hand, feeble changes in the membrane-enzyme interaction, of the order of 0·7–0·8 kcal/mol, would be enough to give a significant change in the values of n (Hill coefficient).