Analisamos a luz refletida por um escaravelho (Phanaeus splendidulus) de cor metálica iridescente que transforma luz não polarizada em circularmente polarizada à esquerda. Animais ou plantas que produzam este tipo de luz não são comuns, apesar desta particular espécie ser bastante disseminada no Brasil. Este fato somado à relativa facilidade de obter um polarizador e uma lâmina de quarto de onda acromática permitem esta demonstração experimental e a análise da polarização circular nos laboratórios de ensino. Comenta-se, também, sobre o biomimetismo e como nanoestruturas que ocorrem nestes insetos podem ser úteis para novas tecnologias em óptica.

We analyze the light reflected by an iridescent-metallic-color scarab (Phanaeus splendidulus) that changes non-polarized light into left-handed-circularly-polarized light. Animals or plants that produce this kind of light are uncommon, although this particular species is fairly widespread in Brazil. This fact, added to the relative ease of obtaining a polarizer and an achromatic quarter wave plate, allow the use of this demonstration experiment and the analysis of circular polarization in teaching laboratories. We also comment about biomimetism and the nanostructures that these insects show and how useful it can be for new technologies in Optics.

Estudou-se a dinâmica das populações de Staphylococcus spp. durante a maturação do queijo Canastra, em três fazendas localizadas no estado de Minas Gerais. A presença dos genes que codificam para a produção das enzimas coagulase (coa), termonuclease (nuc) e produção de enterotoxinas (sea, seb, sec e sed), em linhagens de Staphylococcus isoladas durante os 60 dias de maturação do queijo foi analisada. Também foi investigada a presença de enterotoxina estafilocócica A, C e D nas amostras de queijo. As amostras de queijo com 0, 7, 15, 30 e 45 dias de maturação apresentaram contagens de Staphylococcus spp. entre 10³ e 10(8)ufc / g. Todos os isolados coagulase positivo nos testes fisiológicos apresentaram o gene coa. Não foi observada associação entre os resultados obtidos com os testes bioquímicos e aqueles obtidos com a PCR usando iniciadores gene-específicos para linhagens coagulase negativa. Os genes da coagulase e termonuclease ocorreram simultaneamente em 41,3% dos Staphylococcus spp. testados. Nenhum dos isolados de Staphylococcus apresentou os genes que codificam para a produção das enterotoxinas SEA, SEB, SEC ou SED. As enterotoxinas A, C ou D não foram detectadas em nenhuma das amostras de queijo analisadas.

The population dynamics of Staphylococcus spp. was studied during the ripening of Canastra Minas cheese at three farms located in the State of Minas Gerais, Brazil. The presence of coagulase (coa), thermonuclease (nuc), and enterotoxin (sea, seb, sec, and sed) genes was investigated in Staphylococcus strains isolated during the 60-day cheese-ripening period. The presence of the staphylococcal enterotoxins A, C, and D was also investigated in the cheese samples. Cheese samples that were matured for 0, 7, 15, 30, and 45 days presented staphylococci counts from 10³ to 10(8)cfu/g. All isolates considered coagulase-positive by physiological tests had the coa gene. However, no association was observed between the results obtained with biochemical tests and those obtained by PCR using gene-specific primers for coagulase-negative strains. Coagulase and thermonuclease genes occurred simultaneously in 41.3% of Staphylococcus spp. tested. None of the investigated Staphylococcus strains expressed enterotoxins SEA, SEB, SEC, and SED. Enterotoxins A, C, and D were not detected in any of the cheese samples.

Hypnophilin and panepoxydone, terpenoids isolated from Lentinus strigosus, have significant inhibitory activity onTrypanosoma cruzi trypanothione reductase (TR). Although they have similar TR inhibitory activity at 10 μg/mL (40.3 μM and 47.6 μM for hypnophilin and panepoxydone, respectively; ~100%), hypnophilin has a slightly greater inhibitory activity (~71%) on T. cruzi amastigote (AMA) growth in vitro as well as on in vitro phytohemagglutinin (PHA)-induced peripheral blood mononuclear (PBMC) proliferation (~70%) compared to panepoxydone (69% AMA inhibition and 91% PBMC inhibition). Hypnophilin and panepoxydone at 1.25 μg/mL had 67% inhibitory activity onLeishmania (Leishmania) amazonensis amastigote-like (AMA-like) growth in vitro. The panepoxydone activity was accompanied by a significant inhibitory effect on PHA-induced PBMC proliferation, suggesting a cytotoxic action. Moreover, incubation of human PBMC with panepoxydone reduced the percentage of CD16+ and CD14+ cells and down-regulated CD19+, CD4+ and CD8+ cells, while hypnophilin did not alter any of the phenotypes analyzed. These data indicate that hypnophilin may be considered to be a prototype for the design of drugs for the chemotherapy of diseases caused by Trypanosomatidae.

Em 10 fazendas da região da Serra do Salitre, MG, foram coletadas amostras de leite, soro fermentado (pingo), coalhada e queijo frescal para avaliar a microbiota de bactérias láticas e leveduras presentes. Uma diversidade menor de bactérias láticas foi observada durante a produção do queijo quando comparada à de leveduras. As espécies de bactérias láticas mais freqüentes foram Lactococcus lactis, Enterococcus spp., Enterococcus faecalis e Streptococcus agalactiae e de leveduras foram Debaryomyces hansenii e Kluyveromyces lactis. Apenas as populações de Enterococcus spp., Enterococcus faecalis e Leuconostoc mesenteroides apresentaram aumento significativo durante a produção do queijo. As espécies de bactérias láticas e leveduras encontradas nos diferentes substratos estudados podem ser responsáveis pelas características de aroma e sabor do queijo artesanal da Serra do Salitre.

Samples of milk, curd, cheese whey, and cheese were collected in 10 farms located at the region of Serra do Salitre, Minas Gerais state. These samples were studied in relation to their lactic acid bacteria and yeast populations. The diversity of lactic acid bacteria species was lower than the diversity of yeasts in these samples. The isolated lactic acid bacteria were Lactococcus lactis, Enterococcus spp., Enterococcus faecalis, and Streptococcus agalactiae; and the yeasts were Debaryomyces hansenii and Kluyveromyces lactis. Only the species Enterococcus spp., Enterococcus faecalis, and Leuconostoc mesenteroides showed an increase in their populations during the production of the artisanal cheese. Lactic acid bacteria and yeasts found in this study could be responsible by the sensorial characteristics of the artisanal cheese produced in the region of Serra do Salitre.