Relationship between glutathione S-transferase, catalase, oxygen consumption, lipid peroxidation and oxidative stress in eggs and larvae of Boophilus microplus (Acarina: Ixodidae)

Glutathione S-transferases (GSTs) are enzymes that act in excretion of physiologic and xenobiotic substances, protecting cells against chemical toxicity and stress. In this work, we characterized the enzymatic activity of GST in eggs and larvae of cattle tick Boophilus microplus, on different days after oviposition and eclosion. The results showed that the GST activity varied depending on the time elapsed after oviposition and eclosion. Molecules involved in mechanism of protection from oxidative stress are correlated with the increase in GST activity. The oxygen consumption kinetics showed a positive correlation with the increase in GST activity during embryogenesis. A high content of thiobarbituric acid reactive substances were observed in egg and larva extracts, indicating that ticks face high oxidative stress during embryogenesis and aging. In eggs and larvae, GST activity can be correlated to kinetic parameters of oxidative stress such as catalase and glutathione. In addition, GST activity showed strong positive correlation with lipid peroxidation, an indication that it plays a role in oxidant defences in eggs.     

Interactions of two natural enemies of Tetranychus evansi, the fungal pathogen Neozygites floridana (Zygomycetes: Entomophthorales) and the predatory mite, Phytoseiulus longipes (Acari: Phytoseiidae)

Tetranychus evansi is an exotic pest of Solanaceous crops in Africa discovered in Zimbabwe in 1979. Two natural enemies, the predatory mite Phytoseiulus longipes and the fungal pathogen Neozygites floridana are important causes of mortality in T. evansi populations in Brazil. The first part of this study assessed the effects of N. floridana on predation and oviposition of P. longipes fed on N. floridana infected T. evansi and T. urticae. No N. floridana hyphal bodies were found in P. longipes after this feeding, demonstrating that N. floridana is not pathogenic to P. longipes and does not affect its oviposition. The second part of the study investigated the time spent on searching for and consuming of eggs on leaf discs with and without N. floridana capilliconidia. Both the searching and the feeding time on the first egg were similar on leaf discs with and without capilliconidia. When P. longipes was offered the choice of feeding on eggs on leaf discs with or without capilliconidia, the numbers of eggs consumed were not different. The only N. floridana effect observed on P. longipes was reduced egg predation. In addition, increased time spent grooming on leaf discs with capilliconidia was observed. P. longipes was efficient in removing most capilliconidia attached to the body through self-grooming behavior. This suggests that although the predator did not avoid areas with capilliconidia, it detected and removed most capilliconidia attached to the body. Increased grooming may account for the lower egg predation rates.     

Development, characterization, and comparative analysis of polymorphism at common bean SSR loci isolated from genic and genomic sources.

Microsatellites or SSRs (single sequence repeats) have been used to construct and integrate genetic maps in crop species, including Phaseolus vulgaris. In the present study, 3 cDNA libraries generated by the Bean EST project (http://lgm.esalq.usp.br/BEST/), comprising a unigene collection of 3126 sequences and a genomic microsatellite-enriched library, were analyzed for the presence of SSRs. A total of 219 expressed sequence tags (ESTs) were found to carry 240 SSRs (named EST-SSR), whereas 714 genomic sequences contained 471 SSRs (named genomic-SSR). A subset of 80 SSRs, 40 EST-SSRs, and 40 genomic-SSRs were evaluated for molecular polymorphism in 23 genotypes of cultivated beans from the Mesoamerican and Andean genetic pools, including Brazilian cultivars and 2 related species. Of the common bean genotypes, 31 EST-SSR loci were polymorphic, yielding 2-12 alleles as compared with 26 polymorphic genomic-SSRs, accounting for 2-7 alleles. Cluster analysis from data using both genic and genomic-SSR revealed a clear separation between Andean and Mesoamerican beans. The usefulness of these loci for distinguishing bean genotypes and genetic mapping is discussed.     

Constitutive activation of smoothened (SMO) in mammary glands of transgenic mice leads to increased proliferation, altered differentiation and ductal dysplasia

The hedgehog signaling network regulates pattern formation, proliferation, cell fate and stem/progenitor cell self-renewal in many organs. Altered hedgehog signaling is implicated in 20-25% of all cancers, including breast cancer. We demonstrated previously that heterozygous disruption of the gene encoding the patched-1 (PTCH1) hedgehog receptor, a negative regulator of smoothened (Smo) in the absence of ligand, led to mammary ductal dysplasia in virgin mice. We now show that expression of activated human SMO (SmoM2) under the mouse mammary tumor virus (MMTV) promoter in transgenic mice leads to increased proliferation, altered differentiation, and ductal dysplasias distinct from those caused by Ptch1 heterozygosity. SMO activation also increased the mammosphere-forming efficiency of primary mammary epithelial cells. However, limiting-dilution transplantation showed a decrease in the frequency of regenerative stem cells in MMTV-SmoM2 epithelium relative to wild type, suggesting enhanced mammosphere-forming efficiency was due to increased survival or activity of division-competent cell types under anchorage-independent growth conditions, rather than an increase in the proportion of regenerative stem cells per se. In human clinical samples, altered hedgehog signaling occurs early in breast cancer development, with PTCH1 expression reduced in approximately 50% of ductal carcinoma in situ (DCIS) and invasive breast cancers (IBC). Conversely, SMO is ectopically expressed in 70% of DCIS and 30% of IBC. Surprisingly, in both human tumors and MMTV-SmoM2 mice, SMO rarely colocalized with the Ki67 proliferation marker. Our data suggest that altered hedgehog signaling may contribute to breast cancer development by stimulating proliferation, and by increasing the pool of division-competent cells capable of anchorage-independent growth.     

Morphologic analysis of the venom gland of Apis mellifera L. (Hymenoptera: Apidae) in populations of Mato Grosso do Sul, Brazil

In Apis mellifera L. the venom gland (also called acid gland) is composed of secretory cells that surround a channel that opens into a reservoir devoid of musculature. This gland can present apical branching. In this study the frequency of branched venom glands in Africanized honeybee workers (A. mellifera) from eleven localities in the state of Mato Grosso do Sul was recorded. The relations among the length of the main duct, the length of the duct from the reservoir to the beginning of branching, the length of the branched segment (when present) and the total length of the gland were also analyzed. The frequency of branched glands varied from 50% to 83% in the workers, indicating that this characteristic is primitive in those bees. The results of the Analysis of Discriminant Functions indicated significant differences in the morphometrical segments of the venom gland (Wilks Lambda = 0.092; F (40, 55) = 3.43; P < 0.001), and permitted a differentiation of the populations studied. Using the Mantel test we verified that there does not exist a significant correlation between the morphologic characteristics and the geographical distance between the localities evaluated (Mantel r = -0.006, P = 0.48). The high frequency of workers with large venom gland in all the apiaries considered makes viable the development of a selection program in order to obtain bees with longer venom glands, aimed at the commercial production of venom by the beekeepers of those localities of Mato Grosso do Sul.     

Mite diversity on plants of different families found in the Brazilian Atlantic Forest

This work reports the occurrence of mites predominantly predatory, phytophagous and with varied feeding habits on plants of the Atlantic Forest vegetation type of the State of S?o Paulo. The objective was to estimate the possible role of the Atlantic Forest vegetation as reservoir of these groups of mites which are also found on plants of agricultural importance. Samples were taken from 187 plant species belonging to 73 families in three vegetation types of the Atlantic Forest from February of 2001 to October of 2002. A total of 2,887 mites belonging to 163 morpho-species of 16 families were collected. Mite diversity was high, especially of predatory mites; these corresponded to 1,562 specimens of 92 morpho-species. Within this group, Phytoseiidae comprised 71% of the specimens and 62% of the morpho-species. Phytophagous mites comprised 836 specimens of 36 morpho-species. Within this group, Tenuipalpidae comprised the larger proportion of specimens (61%) whereas Tetranychidae corresponded to the larger proportion of morpho-species (64%). Mites with varied feeding habits corresponded to 491 specimens of 36 morpho-species. In this group, the larger proportion of specimens (52%) consisted of Ascidae and the larger proportion of morpho-species (42%) consisted of Tydeinae (family Tydeidae). High abundance and high morpho-species richness of mites of predominantly predatory, phytophagous and variable feeding habits were observed on 17, five and nine plant species, respectively. The results obtained suggest the importance of plants of the studied vegetation as reservoirs of predatory mites.     

Effects of Ethanolic Extract of Cynara cardunculus (Artichoke) Leaves on Neuroinflammatory and Neurochemical Parameters in a Diet-Induced Mice Obesity Model

Neurochemical Research - This study aimed to evaluate the effect of Cynara cardunculus leaf ethanol extract on inflammatory and oxidative stress parameters in the hypothalamus, prefrontal cortex,...     

Role of cyclooxygenase-2 in Trypanosoma cruzi survival in the early stages of parasite host-cell interaction

Chagas disease, caused by the intracellular protozoan Trypanosoma cruzi, is a serious health problem in Latin America. During this parasitic infection, the heart is one of the major organs affected. The pathogenesis of tissue remodelling, particularly regarding cardiomyocyte behaviour after parasite infection and the molecular mechanisms that occur immediately following parasite entry into host cells are not yet completely understood. When cells are infected with T. cruzi, they develop an inflammatory response, in which cyclooxygenase-2 (COX-2) catalyses rate-limiting steps in the arachidonic acid pathway. However, how the parasite interaction modulates COX-2 activity is poorly understood. In this study, the H9c2 cell line was used as our model and we investigated cellular and biochemical aspects during the initial 48 h of parasitic infection. Oscillatory activity of COX-2 was observed, which correlated with the control of the pro-inflammatory environment in infected cells. Interestingly, subcellular trafficking was also verified, correlated with the control of Cox-2 mRNA or the activated COX-2 protein in cells, which is directly connected with the assemble of stress granules structures. Our collective findings suggest that in the very early stage of the T. cruzi-host cell interaction, the parasite is able to modulate the cellular metabolism in order to survives.     

Mir-190b negatively contributes to the Trypanosoma cruzi- infected cell survival by repressing PTEN protein expression

Chagas disease, which is caused by the intracellular protozoanTrypanosoma cruzi, is a serious health problem in Latin America. The heart is one of the major organs affected by this parasitic infection. The pathogenesis of tissue remodelling, particularly regarding cardiomyocyte behaviour after parasite infection, and the molecular mechanisms that occur immediately following parasite entry into host cells are not yet completely understood. Previous studies have reported that the establishment of parasitism is connected to the activation of the phosphatidylinositol-3 kinase (PI3K), which controls important steps in cellular metabolism by regulating the production of the second messenger phosphatidylinositol-3,4,5-trisphosphate. Particularly, the tumour suppressor PTEN is a negative regulator of PI3K signalling. However, mechanistic details of the modulatory activity of PTEN on Chagas disease have not been elucidated. To address this question, H9c2 cells were infected with T. cruzi Berenice 62 strain and the expression of a specific set of microRNAs (miRNAs) were investigated. Our cellular model demonstrated that miRNA-190b is correlated to the decrease of cellular viability rates by negatively modulating PTEN protein expression in T. cruzi-infected cells.