Effects of pregnancy and protein-energy malnutrition on monooxygenase O-dealkylation activity in rat liver microsomes

Xenobiotic metabolism is influenced by a variety of physiological and environmental factors including pregnancy and nutritional status of the individual. Pregnancy has generally been reported to cause a depression of hepatic monooxygenase activities. Low-protein diets and protein-energy malnutrition have also been associated with a reduced activity of monooxygenases in nonpregnant animals. We investigated the combined effects of pregnancy and protein-energy malnutrition on liver monooxygenase O-dealkylation activity. On pregnancy day 0 rats were assigned at random to a group fed ad libitum (well-nourished, WN) or to a malnourished group (MN) which received half of the WN food intake (12 g/day). WN and MN rats were killed on days 0 (nonpregnant), 11 or 20 of pregnancy and ethoxy- (EROD), methoxy- (MROD) and penthoxy- (PROD) resorufin O-dealkylation activities were measured in liver microsomes. Only minor changes in enzyme activities were observed on pregnancy day 11, but a clear-cut reduction of monooxygenase activities (pmol resorufin min-1 mg protein-1) was noted near term (day 0 vs 20, means ± SD, Student t-test, P<0.05) in WN (EROD: 78.9 ± 15.1 vs 54.6 ± 10.2; MROD: 67.8 ± 10.0 vs 40.9 ± 7.2; PROD: 6.6 ± 0.9 vs 4.3 ± 0.8) and in MN (EROD: 89.2 ± 23.9 vs 46.9 ± 15.0; MROD: 66.8 ± 13.8 vs 27.9 ± 4.4; PROD: 6.3 ± 1.0 vs 4.1 ± 0.6) dams. On pregnancy day 20 MROD was lower in MN than in WN dams. Malnutrition did not increase the pregnancy-induced reduction of EROD and PROD activities. Thus, the present results suggest that the activities of liver monooxygenases are reduced in near-term pregnancy and that protein-energy malnutrition does not alter EROD or PROD in pregnant rats.

Genetic characterization of morphologically variant strains of Paracoccidioides brasiliensis

Molecular characterization of Paracoccidioides brasiliensis variant strains that had been preserved under mineral oil for decades was carried out by random amplified polymorphic DNA analysis (RAPD). On P. brasiliensis variants in the transitional phase and strains with typical morphology, RAPD produced reproducible polymorphic amplification products that differentiated them. A dendrogram based on the generated RAPD patterns placed the 14 P. brasiliensis strains into five groups with similarity coefficients of 72%. A high correlation between the genotypic and phenotypic characteristics of the strains was observed. A 750 bp-RAPD fragment found only in the wild-type phenotype strains was cloned and sequenced. Genetic similarity analysis using BLASTx suggested that this RAPD marker represents a putative domain of a hypothetical flavin-binding monooxygenase (FMO)-like protein of Neurospora crassa.

Land-use systems affect Archaeal community structure and functional diversity in western Amazon soils

The study of the ecology of soil microbial communities at relevant spatial scales is primordial in the wide Amazon region due to the current land use changes. In this study, the diversity of the Archaea domain (community structure) and ammonia-oxidizing Archaea (richness and community composition) were investigated using molecular biology-based techniques in different land-use systems in western Amazonia, Brazil. Soil samples were collected in two periods with high precipitation (March 2008 and January 2009) from Inceptisols under primary tropical rainforest, secondary forest (5-20 year old), agricultural systems of indigenous people and cattle pasture. Denaturing gradient gel electrophoresis of polymerase chain reaction-amplified DNA (PCR-DGGE) using the 16S rRNA gene as a biomarker showed that archaeal community structures in crops and pasture soils are different from those in primary forest soil, which is more similar to the community structure in secondary forest soil. Sequence analysis of excised DGGE bands indicated the presence of crenarchaeal and euryarchaeal organisms. Based on clone library analysis of the gene coding the subunit of the enzyme ammonia monooxygenase (amoA) of Archaea (306 sequences), the Shannon-Wiener function and Simpson's index showed a greater ammonia-oxidizing archaeal diversity in primary forest soils (H' = 2.1486; D = 0.1366), followed by a lower diversity in soils under pasture (H' = 1.9629; D = 0.1715), crops (H' = 1.4613; D = 0.3309) and secondary forest (H' = 0.8633; D = 0.5405). All cloned inserts were similar to the Crenarchaeota amoA gene clones (identity > 95 %) previously found in soils and sediments and distributed primarily in three major phylogenetic clusters. The findings indicate that agricultural systems of indigenous people and cattle pasture affect the archaeal community structure and diversity of ammonia-oxidizing Archaea in western Amazon soils.

Involvement of miR-30c in resistance to doxorubicin by regulating YWHAZ in breast cancer cells

MicroRNAs (miRNAs) are small RNA molecules that modulate gene expression implicated in cancer, which play crucial roles in diverse biological processes, such as development, differentiation, apoptosis, and proliferation. The aim of this study was to investigate whether miR-30c mediated the resistance of breast cancer cells to the chemotherapeutic agent doxorubicin (ADR) by targeting tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein zeta (YWHAZ). miR-30c was downregulated in the doxorubicin-resistant human breast cancer cell lines MCF-7/ADR and MDA-MB-231/ADR compared with their parental MCF-7 and MDA-MB-231 cell lines, respectively. Furthermore, we observed that transfection of an miR-30c mimic significantly suppressed the ability of MCF-7/ADR to resist doxorubicin. Moreover, the anti-apoptotic gene YWHAZ was confirmed as a target of miR-30c by luciferase reporter assay, and further studies indicated that the mechanism for miR-30c on the sensitivity of breast cancer cells involved YWHAZ and its downstream p38 mitogen-activated protein kinase (p38MAPK) pathway. Together, our findings provided evidence that miR-30c was one of the important miRNAs in doxorubicin resistance by regulating YWHAZ in the breast cancer cell line MCF-7/ADR.