Overexpression of the COX2 translational activator, Pet111p, prevents translation of COX1 mRNA and cytochrome c oxidase assembly in mitochondria of Saccharomyces cerevisiae

Dramatically elevated levels of the COX2 mitochondrial mRNA-specific translational activator protein Pet111p interfere with respiratory growth and cytochrome c oxidase accumulation. The respiratory phenotype appears to be caused primarily by inhibition of the COX1 mitochondrial mRNA translation, a finding confirmed by lack of cox1Delta::ARG8(m) reporter mRNA translation. Interference with Cox1p synthesis depends to a limited extent upon increased translation of the COX2 mRNA, but is largely independent of it. Respiratory growth is partially restored by a chimeric COX1 mRNA bearing the untranslated regions of the COX2 mRNA, and by overproduction of the COX1 mRNA-specific activators, Pet309p and Mss51p. These results suggest that excess Pet111p interacts unproductively with factors required for normal COX1 mRNA translation. Certain missense mutations in PET111 alleviate the interference with COX1 mRNA translation but do not completely restore normal respiratory growth in strains overproducing Pet111p, suggesting that elevated Pet111p also perturbs assembly of newly synthesized subunits into active cytochrome c oxidase. Thus, this severe imbalance in translational activator levels appears to cause multiple problems in mitochondrial gene expression, reflecting the dual role of balanced translational activators in cooperatively regulating both the levels and locations of organellar translation.     

Parasitological characteristics of Schistosoma mansoni infection in swiss mice with underlying malnutrition

The effects of a protein-restricted diet (8% protein, 81% carbohydrate and 11% lipids) on Schistosoma mansoni infectivity, fecal egg excretion and intestinal egg distribution in Swiss (SW) mice were studied. Pregnant mice received a deficient diet from the middle of gestation until delivery. Seven-days-old mice were exposed to 50 cercariae (BH strain, Brazil). Offspring mice had a free access to the deficient diet since lactation until adulthood. The controls were fed with a commercial mice diet. A parasitological examination was performed between six and eight weeks post-infection while both groups were necropsied one week later. Mice on the experimental diet showed a significant loss in body weight. There was no significant difference (p > 0.05) in pre-patent period, kinetics of egg excretion and worm recovery from mice on either diet. Significant differences (p < 0.05) were found concerning to the percentage of deposited eggs in the distal segment of the small intestine from hosts on the experimental diet. Our data suggest that experimental malnutrition induced for a long term has no detrimental effect on the acute schistosomiais infection in SW mice.     

Viral hepatitis markers in antepartum and postpartum women in Rio de Janeiro,Brazil

A seroprevalence study was carried out among a group of women in Rio de Janeiro to determine the prevalence of different markers for viral hepatitis given the limited data among healthy populations. Blood samples collected and tested from 874 women before or after delivery in a public county maternity hospital demonstrated age to be directly related to markers for hepatitis A virus and hepatitis B virus (HBV) infection. The prevalence of HBV and hepatitis C virus infection were lower than that observed in the blood donor population and might be explained by the younger age group and gender.     

Existence of a true phosphofructokinase in Bacillus sphaericus: cloning and sequencing of the pfk gene

Some strains of Bacillus sphaericus are entomopathogenic to mosquito larvae, which transmit diseases, such as filariasis and malaria, affecting millions of people worldwide. This species is unable to use hexoses and pentoses as unique carbon sources, which was proposed to be due to the lack of glycolytic enzymes, such as 6-phosphofructokinase (PFK). In this study, PFK activity was detected and the pfk gene was cloned and sequenced. Furthermore, this gene was shown to be present in strains belonging to all the homology groups of this heterogeneous species, in which PFK activity was also detected. A careful sequence analysis revealed the conservation of different catalytic and regulatory residues, as well as the enzyme's phylogenetic affiliation with the family of allosteric ATP-PFK enzymes.     

Aromatic DNA adduct levels in coke oven workers: correlation with polymorphisms in genes GSTP1, GSTM1, GSTT1 and CYP1A1

The aim of this study was to use DNA adducts levels, detected by 32P-postlabelling, as a biomarker to assess human exposure to polycyclic aromatic hydrocarbons (PAHs) from a coke oven plant and explore the possible association between CYP1A1 MspI, GSTP1, GSTM1 and GSTT1 genotypes, and smoking status on bulky DNA adduct formation. A large amount of inter-individual variation in adduct level was observed among workers with the same job and the same smoking habits. No significant differences were observed in DNA adduct levels between the coke oven workers and control group. Smokers in the control group had significantly higher DNA adducts than the non-smokers in the same group (35.13+/-21.11 versus 11.18+/-8.00, per 10(8) nucleotides, P=0.003). In this group, the correlation between the level of DNA adducts and the cigarettes smoked was strongly significant (r=0.70, P<0.0005), but no correlation was found among the coke oven workers. Among non-smokers there was a significant difference between the control group and the coke oven workers (11.18+/-8.00 versus 24.62+/-15.20, per 10(8) nucleotides, P=0.03). These results suggests that tobacco smoke could behave as a confounding factor for evaluation of DNA adducts arising from occupational exposure. The levels of DNA adducts in smokers not occupationally exposed to PAHs is dependent on the polymorphisms CYP1A1 MspI in the 3' non-coding region (49.04+/-22.18 versus 25.85+/-15.87, per 10(8) nucleotides, P<0.05), but no effect was observed for the GST genotypes studied.     

Effect of phenanthrene and Rhodotorula glutinis on arbuscular mycorrhizal fungus colonization of maize roots

The effect of the polycyclic aromatic hydrocarbon (PAH) phenanthrene and the yeast Rhodotorula glutinis on the arbuscular mycorrhizal fungus (AMF) Glomus geosporum colonizing maize roots, was studied. During a 90-day experiment, the highest G. geosporum colonization values were found in control plants. Mycorrhiza root length, measured both on the basis of percentage of root colonization and on the activity of succinate dehydrogenase, showed similar patterns in different phenanthrene treatments. The presence of phenanthrene in the substrate reduced G. geosporum intraradical colonization. The presence of R. glutinis did not enhance AMF colonization in the presence of phenanthrene. The biomass of the external mycelium estimated on the basis of the fatty acid 16:1 omega 5 concentration showed a progressive increase through time, and the amounts of this fatty acid differed among treated and untreated substrates. However, this increase was found to be lowest in the phenanthrene and Rhodotorula treatment at 60 days. There was less phenanthrene accumulation in roots of maize inoculated with AMF and the yeast than in roots inoculated only with AMF. A similar pattern was observed in the phenanthrene content of G. geosporum spores collected after 90 days.     

The developmental role of serotonin: news from mouse molecular genetics

New genetic models that target the serotonin system show that transient alterations in serotonin homeostasis cause permanent changes to adult behaviour and modify the fine wiring of brain connections. These findings have revived a long-standing interest in the developmental role of serotonin. Molecular genetic approaches are now showing us that different serotonin receptors, acting at different developmental stages, modulate different developmental processes such as neurogenesis, apoptosis, axon branching and dendritogenesis. Our understanding of the specification of the serotonergic phenotype is improving. In addition, studies have revealed that serotonergic traits are dissociable, as there are populations of neurons that contain serotonin but do not synthesize it.