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Microbial secondary metabolites are low molecular mass products, not essential for growth of the producing cultures, but very important for human health. They include antibiotics, antitumor agents, cholesterol-lowering drugs, and others. They have unusual structures and are usually formed during the late growth phase of the producing microorganisms. Its synthesis can be influenced greatly by manipulating the type and concentration of the nutrients formulating the culture media. Among these nutrients, the effect of the carbon sources has been the subject of continuous studies for both, industry and research groups. Different mechanisms have been described in bacteria and fungi to explain the negative carbon catabolite effects on secondary metabolite production. Their knowledge and manipulation have been useful either for setting fermentation conditions or for strain improvement. During the last years, important advances have been reported on these mechanisms at the biochemical and molecular levels. The aim of the present review is to describe these advances, giving special emphasis to those reported for the genus Streptomyces.

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Antihypertensive activity X 0120Synthesis and Antihypertensive Effects of New Methylthiomorpholinphenol Derivatives. -The novel compounds (I) are evaluated for their antihypertensive activity. The results are discussed in detail in comparison with other cardiovascular drugs such as captopril, losartan and omapatrilat. LQM303 (Ic) exhibits the best decreasing effect in both systolic and diastolic pressure and the best heart rate decreasing effect. -(VELAZQUEZ, A. M.; MARTINEZ, L.; ABREGO, V.; BALBOA, M. A.; TORRES, L. A.; CAMACHO, B.; DIAZ-BARRIGA, S.; ROMERO, A.; LOPEZ--CASTANARES, R.; ANGELES*, E.; Eur.

In Streptomyces, carbon utilization is of significant importance for the expression of genes involved in morphological differentiation and antibiotic production. Glucose is mainly transported by GlcP, a membrane protein encoded by glcp. In Streptomyces coelicolor, this protein is encoded by sco5578. However, there is little information about the physiology of the GlcP promoter in Streptomyces. The aim of the present work was to clone and perform a functional analysis of the sp7066 promoter (ortholog of sco5578) from Streptomyces peucetius var. caesius. Hydrophobicity and cellular location analysis of the putative amino acid sequence of the cloned gene predicted SP7066 would be a membrane protein with a topology of six plus six transmembrane segments interrupted by a large cytoplasmic loop. In silico analysis of the upstream region of the sp7066 transcription initiation site predicted the sequences 5'-AGGAATAGT-3' and 5'-TTGACT-3' for regions -10 and -35 of sp7066 promoter. To reflect sp7066 expression, the promoter sequence was amplified, subcloned, and fused to the egfp reporter gene. Immunoblot analysis revealed that D-glucose and its analog 2-deoxyglucose were able to induce sp7066 expression. This effect was not modified by the presence of equimolar concentrations of D-galactose or N-acetylglucosamine. No expression of egfp was detected with the use of other carbon sources such as L-arabinose, D-fructose, and glycerol. Based on these analyses, we conclude that D-glucose is a preferred carbon source in S. peucetius var. caesius and that the sp7066 expression product, a putative non-PTS glucose permease, likely is a H+/symporter, localized to the membrane, and shows a strong specificity for D-glucose for inducing expression.

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An accurate and precise knowledge of the amount of energy introduced into prebiotic discharge experiments is important to understand the relative roles of different energy sources in the synthesis of organic compounds in the primitive Earth's atmosphere and other planetary atmospheres. Two methods widely used to determine the power of spark discharges were evaluated, namely calorimetric and oscilloscopic, using a chemically inert gas. The power dissipated by the spark in argon at 500 Torr was determined to be 2.4 (+12%/-17%) J s-1 by calorimetry and 5.3 (+/- 15%) J s-1 by the oscilloscope. The difference between the two methods was attributed to (1) an incomplete conversion of the electric energy into heat, and (2) heat loss from the spark channel to the connecting cables through the electrodes. The latter contribution leads to an unwanted effect in the spark channel by lowering the spark product yields as the spark channel cools by mixing with surrounding air and by losing heat to the electrodes. Once the concentrations of the spark products have frozen at the freeze-out temperature, any additional loss of heat from the spark channel to the electrodes has no consequence in product yields. Therefore, neither methods accurately determines the net energy transferred to the system. With a lack of a quantitative knowledge of the amount of heat loss from the spark channel during the interval from ignition of the spark to when the freeze-out temperature is reached, it is recommended to derive the energy yields of the spark products from the mean value of the two methods with the uncertainty being their standard deviation. For the case of argon at 500 Torr, this would be 3.8 (+/-50%) J s-1.