Role of error-prone DNA polymerases in spontaneous mutagenesis in Caulobacter crescentus.

Spontaneous mutations are important players in evolution. Nevertheless, there is a paucity of information about the mutagenic processes operating in most bacterial species. In this work, we implemented two forward mutational markers for studies in Caulobacter crescentus. We confirmed previous results in which A:T → G:C transitions are the most prevalent type of spontaneous base substitutions in this organism, although there is considerable deviation from this trend in one of the loci analyzed. We also investigated the role of dinB and imuC, encoding error-prone DNA polymerases, in spontaneous mutagenesis in this GC-rich organism. Both dinB and imuC mutant strains show comparable mutation rates to the parental strain. Nevertheless, both strains show differences in the base substitution patterns, and the dinB mutant strain shows a striking reduction in the number of spontaneous -1 deletions and an increase in C:G → T:A transitions in both assays.

Aptos aos trabalhos braçais, suscetíveis aos vícios morais: representações do homem negro na Revista Educação Physica (1939-1944) / Suitable for manual labor; susceptible to the moral vices: representations of black men in the Journal Educação Physica (1939-1944) / Aptos a los trabajos manuales, susceptibles a los vicios morales: representaciones del hombre negro en la Revista Educação Physica (1939 ­ 1944)

A partir dos marcadores de gênero e raça, este texto analisa as representações do homem negro na revista Educação Physica entre 1939 e 1944, período em que Francisco de Assis Hollanda Loyola ficou no cargo de editor técnico do periódico. Para tanto, as edições compreendidas entre os números 34 e 81 foram acessadas e analisadas, com base nos pressupostos teórico-metodológicos da História Cultural. Em um período em que raça, povo e nação eram entendidos quase como sinônimos, a revista Educação Physica veiculou representações que tornam os homens negros visíveis por seus dotes físicos e suas fragilidades morais. "Naturalmente" propensos aos vícios e às tarefas braçais, as representações dos homens negros são produzidas na negação de suas características étnico-raciais, enfatizando, como efeito, os predicados provenientes dos corpos brancos

Based on gender and race markers, this text analyzes representations of black men in the magazine Educação Physica between 1939 and 1944, when Francisco de Assis Hollanda Loyola was its technical editor. Issues 34-81 were analyzed under the theoretical/methodological assumptions of Cultural History. In a period in which race, people, and nation were understood almost as synonyms, Educação Physica conveyed representations that portrayed black men according to their physical strengths and their moral weaknesses. "Naturally" prone to addiction and manual labor, black men's depictions denied their racial/ethnic characteristics, emphasizing white bodies' attributes as their effect

A partir de los marcadores de género y raza, este texto analiza las representaciones del hombre negro en la revista brasileña Educação Physica, de 1939 a 1944, periodo en que Francisco de Assis Hollanda Loyola ocupó el cargo de editor técnico del periódico. Para ello, las ediciones emprendidas entre los números 34 y 81 fueron accedidas y analizadas a partir de los presupuestos teórico/metodológico de la Historia Cultural. En un periodo en que raza, pueblo y nación eran comprendidos casi como sinónimos, la revista brasileña Educación Physica vehiculó representaciones que tornan los hombres negros visibles por sus dotes físicos y sus debilidades morales. "Naturalmente" propensos a los vicios y a las tareas manuales que requieren esfuerzo físico, las representaciones de los hombres negros son producidas en la negación de sus características étnico-racial, enfatizando como efecto los predicados provenientes de los cuerpos blancos

EGFR Signaling Regulates Maspin/SerpinB5 Phosphorylation and Nuclear Localization in Mammary Epithelial Cells.

Maspin (SerpinB5) is a non-inhibitory serpin (serine protease inhibitor) with very diverse biological activities including regulation of cell adhesion, migration, death, control of gene expression and oxidative stress response. Initially described as a tumor and metastasis suppressor, clinical data brought controversies to the field, as some studies reported no correlation between SerpinB5 expression and prognosis value. These data underscore the importance of understanding SerpinB5 function in a normal physiological context and the molecular mechanism involved. Several SerpinB5 phosphoforms have been detected in different cell lines, but the signaling pathways involved and the biological significance of this post-translational modification in vivo remains to be explored. In this study we investigated SerpinB5 expression, subcellular localization and phosphorylation in different stages of the mouse mammary gland development and the signaling pathway involved. Here we show that SerpinB5 is first detected in late pregnancy, reaches its highest levels in lactation and remains at constant levels during post-lactational regression (involution). Using high resolution isoelectric focusing followed but immunoblot, we found at least 8 different phosphoforms of SerpinB5 during lactation, which decreases steadily at the onset of involution. In order to investigate the signaling pathway involved in SerpinB5 phosphorylation, we took advantage of the non-transformed MCF-10A model system, as we have previously observed SerpinB5 phosphorylation in these cells. We detected basal levels of SerpinB5 phosphorylation in serum- and growth factor-starved cells, which is due to amphiregulin autocrine activity on MCF-10A cells. EGF and TGF alpha, two other EGFR ligands, promote important SerpinB5 phosphorylation. Interestingly, EGF treatment is followed by SerpinB5 nuclear accumulation. Altogether, these data indicate that SerpinB5 expression and phosphorylation are developmentally regulated. In vitro analyses indicate that SerpinB5 phosphorylation is regulated by EGFR ligands, but EGF appears to be the only able to induce SerpinB5 nuclear localization.

Obesity impairs lactation performance in mice by inducing prolactin resistance.

Obesity reduces breastfeeding success and lactation performance in women. However, the mechanisms involved are not entirely understood. In the present study, female C57BL/6 mice were chronically exposed to a high-fat diet to induce obesity and subsequently exhibited impaired offspring viability (only 15% survival rate), milk production (33% reduction), mammopoiesis (one-third of the glandular area compared to control animals) and postpartum maternal behaviors (higher latency to retrieving and grouping the pups). Reproductive experience attenuated these defects. Diet-induced obese mice exhibited high basal pSTAT5 levels in the mammary tissue and hypothalamus, and an acute prolactin stimulus was unable to further increase pSTAT5 levels above basal levels. In contrast, genetically obese leptin-deficient females showed normal prolactin responsiveness. Additionally, we identified the expression of leptin receptors specifically in basal/myoepithelial cells of the mouse mammary gland. Finally, high-fat diet females exhibited altered mRNA levels of ERBB4 and NRG1, suggesting that obesity may involve disturbances to mammary gland paracrine circuits that are critical in the control of luminal progenitor function and lactation. In summary, our findings indicate that high leptin levels are a possible cause of the peripheral and central prolactin resistance observed in obese mice which leads to impaired lactation performance.