Microbial reduction of cyclohexanones

A Brazilian strain of the bacteria Serratia rubidaea CCT 5742 quantitatively reduced 4-tert-butylcyclohexanone and 4-methylcyclohexanone to the less thermodynamically stable diastereoisomeric alcohols cis-4-tert-butylcyclohexanol and cis-4-methylcyclohexanol with a diastereoisomeric excesses (de) of 96% and 44%, respectively. 2-Methylcyclohexanone was also totally reduced to the corresponding alcohols affording the trans-(+)-(1S, 2S)-2-methylcyclohexanol with 78% of de and an enantiomeric excess (ee) of 80%. The cis-(+)-(1S, 2R)-2-methylcyclohexanol was obtained in 98% ee.     

Statins and Antimicrobial Effects: Simvastatin as a Potential Drug against Staphylococcus aureus Biofilm

Statins are important lipid-lowering agents with other pleiotropic effects. Several studies have explored a possible protective effect of statins to reduce the morbidity and mortality of many infectious diseases. Staphylococcus aureus is one of the main pathogens implicated in nosocomial infections; its ability to form biofilms makes treatment difficult. The present study observed the MIC of atorvastatin, pravastatin and simvastatin against S. aureus, Pseudomonas aeruginosa, Escherichia coli and Enterococcus faecalis. Simvastatin was the only agent with activity against clinical isolates and reference strains of methicilin-sensitive S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA). Thus, the effects of simvastatin on the growth, viability and biofilm formation of S. aureus were tested. In addition, a possible synergistic effect between simvastatin and vancomycin was evaluated. Simvastatin’s MIC was 15.65 µg/mL for S. aureus 29213 and 31.25 µg/mL for the other strains of S. aureus. The effect of simvastatin was bactericidal at 4xMIC and bacteriostatic at the MIC concentration. No synergistic effect was found between simvastatin and vancomycin. However, the results obtained against S. aureus biofilms showed that, in addition to inhibiting adhesion and biofilm formation at concentrations from 1/16xMIC to 4xMIC, simvastatin was also able to act against mature biofilms, reducing cell viability and extra-polysaccharide production. In conclusion, simvastatin showed pronounced antimicrobial activity against S. aureus biofilms, reducing their formation and viability.     

Structural model for an AxxxG-mediated dimer of surfactant-associated protein C.

The pulmonary surfactant prevents alveolar collapse and is required for normal pulmonary function. One of the important components of the surfactant besides phospholipids is surfactant-associated protein C (SP-C). SP-C shows complex oligomerization behavior and a transition to beta-amyloid-like fibril structures, which are not yet fully understood. Besides this nonspecific oligomerization, MS and chemical cross-linking data combined with CD spectra provide evidence of a specific, mainly alpha-helical, dimer at low to neutral pH. Furthermore, resistance to CNBr cleavage and dual NMR resonances of porcine and human recombinant SP-C with Met32 replaced by isoleucine point to a dimerization site located at the C-terminus of the hydrophobic alpha-helix of SP-C, where a strictly conserved heptapeptide sequence is found. Computational docking of two SP-C helices, described here, reveals a dimer with a helix-helix interface that strikingly resembles that of glycophorin A and is mediated by an AxxxG motif similar to the experimentally determined GxxxG pattern of glycophorin A. It is highly likely that mature SP-C adopts such a dimeric structure in the lamellar bilayer systems found in the surfactant. Dimerization has been shown in previous studies to have a role in sorting and trafficking of SP-C and may also be important to the surfactant function of this protein.     

Investment in Mate Guarding May Compensate for Constraints on Ejaculate Production in the Cricket Gryllodes sigillatus

Although there is a corpus of evidence that females of many taxa are choosy about males, there is less information on how males may react to females of different 'quality' (i.e. potential fecundity). The cricket Gryllodes sigillatus shows distinct mate guarding behaviour. We examined how long males mate guard females of different sizes (reflecting egg load and potential fecundity). We also examined the sperm number in ampullae donated to females of different sizes to see if males make a concomitant difference in investment in ejaculate. We also examined mate-guarding behaviour and ejaculate size of males mated to virgin and nonvirgin females of the same size to see if males equate size with increased age and increased likelihood of mating (increased sperm competition). The results showed that males mate guard larger females for longer but make no difference in ejaculate investment between sizes of female. Males make no significant difference in mate guarding investment or ejaculate investment between virgins and nonvirgins of the same size. There is evidence that other species of crickets do alter their ejaculate depending on the female size and mating history, but have less distinct guarding behaviour. We suggest that mate-guarding investment in G. sigillatus may serve a similar function to that of ejaculate investment in other crickets.     

A higher-order entity formed by the flexible assembly of RAP1 with TRF2

Telomere integrity is essential to maintain genome stability, and telomeric dysfunctions are associated with cancer and aging pathologies. In human, the shelterin complex binds TTAGGG DNA repeats and provides capping to chromosome ends. Within shelterin, RAP1 is recruited through its interaction with TRF2, and TRF2 is required for telomere protection through a network of nucleic acid and protein interactions. RAP1 is one of the most conserved shelterin proteins although one unresolved question is how its interaction may influence TRF2 properties and regulate its capacity to bind multiple proteins. Through a combination of biochemical, biophysical and structural approaches, we unveiled a unique mode of assembly between RAP1 and TRF2. The complete interaction scheme between the full-length proteins involves a complex biphasic interaction of RAP1 that directly affects the binding properties of the assembly. These results reveal how a non-DNA binding protein can influence the properties of a DNA-binding partner by mutual conformational adjustments.     

激光及γ射线对有丝分裂染色体畸变感应现象的比较

波长514nm的激光照射可用于研究激光导致有丝分裂染色体畸变的效应。本文提供了一种新的辐照系统,能用于研究突变的感应现象,并与从γ-线辐射源获得的结果进行了比较。 Abstract:Laser irradiation at wavelength 514 nm was used to study the effect of lasers in inducing chromosomal aberrations at mitosis.This study offers a new radiation system which could be used for the induction of mutations.Results are compared with those obtained from studies using γ-rays as irradiation source.     

Production and purification of an untagged recombinant pneumococcal surface protein A (PspA4Pro) with high-purity and low endotoxin content

Applied Microbiology and Biotechnology - Streptococcus pneumoniae is the main cause of pneumonia, meningitis, and other conditions that kill thousands of children every year worldwide. The...