Genes for the biosynthesis of spinosyns: applications for yield improvement in Saccharopolyspora spinosa

Spinosyns A and D are the active ingredients in an insect control agent produced by fermentation of Saccharopolyspora spinosa. Spinosyns are macrolides with a 21-carbon, tetracyclic lactone backbone to which the deoxysugars forosamine and tri-O-methylrhamnose are attached. The spinosyn biosynthesis genes, except for the rhamnose genes, are located in a cluster that spans 74 kb of the S. spinosa genome. DNA sequence analysis, targeted gene disruptions and bioconversion studies identified five large genes encoding type I polyketide synthase subunits, and 14 genes involved in sugar biosynthesis, sugar attachment to the polyketide or cross-bridging of the polyketide. Four rhamnose biosynthetic genes, two of which are also necessary for forosamine biosynthesis, are located outside the spinosyn gene cluster. Duplication of the spinosyn genes linked to the polyketide synthase genes stimulated the final step in the biosynthesis — the conversion of the forosamine-less pseudoaglycones to endproducts. Duplication of genes involved in the early steps of deoxysugar biosynthesis increased spinosyn yield significantly. Journal of Industrial Microbiology & Biotechnology (2001) 27, 399–402. Received 31 May 2001/ Accepted in revised form 09 July 2001     

Mitochondrial glutathione modulates TNF-alpha-induced endothelial cell dysfunction.

The effect of glutathione (GSH) depletion by L-buthionine-[S,R]-sulphoximine (BSO) on tumor necrosis factor-alpha (TNF-alpha)-induced adhesion molecule expression and mononuclear leukocyte adhesion to human umbilical vein endothelial cells (HUVECs) was investigated. Cells with marked depletion of cytoplasmic GSH, but with an intact pool of mitochondrial GSH, only slightly enhanced TNF-alpha-induced E-selectin and vascular cell adhesion molecule-1 (VCAM-1) expression, compared with the control. However, TNF-a-induced expression of both molecules was markedly enhanced when the mitochondrial GSH pool was diminished to <15% of the control. In contrast, TNF-alpha-induced intercellular adhesion molecule-1 (ICAM-1) expression was not affected by the depletion of either cytoplasmic or mitochondrial GSH. Marked enhancement of TNF-alpha-induced adhesion molecule expression by the depletion of mitochondrial GSH resulted in increased in mononuclear leukocyte adhesion to treated HUVECs, compared with the control. These effects parallel reactive oxygen species (ROS) formation by the depletion of mitochondrial but not cytoplasmic GSH. Our findings demonstrate that depletion of mitochondrial GSH renders more ROS generation in HUVECs, and mitochondrial GSH modulates TNF-alpha-induced adhesion molecule expression and mononuclear leukocyte adhesion in HUVECs.     

Alpine SteinadlerAquila chrysaetos durch Bleivergiftung gef?hrdet?

In 1990 and 1994, two males of Golden Eagles were found with small lead particles in their stomachs. Both individuals died soon after they had been taken sitting on the soil in bad condition. There are some findings of dead eagles in the same area which showed no sign of having been injured. The two cases of presumed lead poisoning coincide with intense efforts to reduce the number of ChamoixRupicapra rupicapra by hunting. The bullets used contain a nucleus of lead and eagles were seen taking the entrails of the shot chamoix.     

Synaptonemal complexes and meiosis in myxomycetes

Synaptonemal complexes (SC) have been observed in spores 18–24 hr past cleavage in natural fruitings of Physarum cinereum, P. bogoriense, Hemitrichia stipitata, Tubifera ferruginosa, and Arcyria incarnata. Laboratory fruitings of Arcyria cinerea, Stemonitis herbatica, and a homothallic isolate of Physarum pusillum also have SC's present in spores during the same postcleavage period. The presence of these paired chromosomes of meiotic prophase in spores of species collected in nature and in a diversity of taxa suggests that the usual position of meiosis in Myxomycetes is inside the postcleavage spore. Criteria are proposed for evaluating the validity of the SC as an indicator of meiosis.     

Levels of genetic polymorphism: marker loci versus quantitative traits.

Species are the units used to measure ecological diversity and alleles are the units of genetic diversity. Genetic variation within and among species has been documented most extensively using allozyme electrophoresis. This reveals wide differences in genetic variability within, and genetic distances among, species, demonstrating that species are not equivalent units of diversity. The extent to which the pattern observed for allozymes can be used to infer patterns of genetic variation in quantitative traits depends on the forces generating and maintaining variability. Allozyme variation is probably not strictly neutral but, nevertheless, heterozygosity is expected to be influenced by population size and genetic distance will be affected by time since divergence. The same is true for quantitative traits influenced by many genes and under weak stabilizing selection. However, the limited data available suggest that allozyme variability is a poor predictor of genetic variation in quantitative traits within populations. It is a better predictor of general phenotypic divergence and of postzygotic isolation between populations or species, but is only weakly correlated with prezygotic isolation. Studies of grasshopper and planthopper mating signal variation and assortative mating illustrate how these characters evolve independently of general genetic and morphological variation. The role of such traits in prezygotic isolation, and hence speciation, means that they will contribute significantly to the diversity of levels of genetic variation within and among species.     

Turnover of the aggregates and cross-linked products of the D1 protein generated by acceptor-side photoinhibition of photosystem II.

It is known that the reaction-center binding protein D1 in photosystem (PS) II is degraded significantly during photoinhibition. The D1 protein also cross-links covalently or aggregates non-covalently with the nearby polypeptides in PS II complexes by illumination. In the present study, we detected the adducts between the D1 protein and the other reaction-center binding protein D2 (D1/D2), the alpha-subunit of cyt b(559) (D1/cyt b(559)), and the antenna chlorophyll-binding protein CP43 (D1/CP43) by SDS/urea-polyacrylamide gel electrophoresis and Western blotting with specific antibodies. The adducts were observed by weak and strong illumination (light intensity: 50-5000 microE m(-2) s(-1)) of PS II membranes, thylakoids and intact chloroplasts from spinach, under aerobic conditions. These results indicate that the cross-linking or aggregation of the D1 protein is a general phenomenon which occurs in vivo as well as in vitro with photodamaged D1 proteins. We found that the formation of the D1/D2, D1/cyt b(559) and D1/CP43 adducts is differently dependent on the light intensity; the D1/D2 heterodimers and D1/cyt b(559) were formed even by illumination with weak light, whereas generation of the D1/CP43 aggregates required strong illumination. We also detected that these D1 adducts were efficiently removed by the addition of stromal components, which may contain proteases, molecular chaperones and the associated proteins. By two-dimensional SDS/urea-polyacrylamide gel electrophoresis, we found that several stromal proteins, including a 15-kDa protein are effective in removing the D1/CP43 aggregates, and that their activity is resistant to SDS.