Cyclic peroxides from a soya lipoxygenase-catalysed oxygenation of methyl linolenate.

Incubation of methyl linolenate with an aqueous extract of soyabean flour at neutral pH gives the hydroperoxyendoperoxides 16-hydroxyperoxy-13,15-endoperoxylinolenate and 9-hydroxyperoxy-10,12-endoperoxylinolenate as the principal oxygenation products in addition to monohydroperoxides. Lipoxygenase I (EC 1.13.11.12) does not catalyse the oxygenation under this condition. The enzyme contributing most to the formation of the hydroperoxyendoperoxides is assumed to be a high molecular mass lipoxygenase aggregate.     

Molecular hybridization analysis of cloned Vicia faba minicircular DNA sequences

Summary Three types of minicircular DNA isolated from Vicia faba mitochondria were cloned in pBR322 plasmids. The correspondence of cloned sequences to the original molecules was verified by coelectrophoresis and by DNA-DNA hybridization with total mitochondrial DNA preparations. It was found that the cloned sequences hybridized not only with the minicirclar DNAs and their derivates, but also with some discrete classes of higher molecular weight DNA and with the major DNA. The data obtained from restriction enzyme analysis of complementary sequences suggested that the majority of them were represented by the minicircular DNAs and by the oligomers. The physical maps of cloned sequences were also prepared. These maps differed significantly. However, reciprocal DNA-DNA hybridization showed the existence of sequence homology between minicircular DNAs.     

Kinetics of unscheduled DNA synthesis in UV-irradiated chicken embryo fibroblasts

Unscheduled DNA synthesis induced by 254-nm UV radiation in chicken embryo fibroblasts was examined for 24 h following irradiation, while cells were kept in the dark. The effect on this repair process of a 2-4 h exposure to photoreactivating light immediately after UV was studied. Initial [3H]thymidine incorporation in the light-treated cells was only slightly different from that in cells not exposed to light, but a distinct difference in rate and cumulative amount of unscheduled DNA synthesis was seen several hours after irradiation. By varying the UV dose and the time allowed for photoreactivation, the amount of dimers (determined as sites sensitive to a M. luteus UV-endonuclease) and non-dimers could be changed. The results of these experiments suggest that excision repair of dimers, rather than non-dimer products, is responsible for the unscheduled DNA synthesis seen after UV irradiation.     

Formation of mineral phosphate microtubes in the presence of halophilic cyanobacteriumMicrocoleus chthonoplastes

In a culture of filamentous cyanobacteriumMicrocoleus chthonoplastes under high phosphorus content and the presence of NaF, formation of aggregated microtubes of 0.8–1.0 m in diameter was obtained. Microtubes contain calcium and phosphorus. These filamentous structures do not represent fossilized bacteria.     

Fructose assimilation by differentiated and undifferentiated variants of Streptomyces roseofulvus

The difference in the growth on fructose between differentiated and adifferentiated variants of Streptomyces roseoflavus var. roseofungini should be attributed to their different capacity in forming the enzyme system for fructose uptake whose action is induced by this carbohydrate. In the cells of the two variants grown on glucose and mannitol, the process of induction occurs in the presence of chloramphenicol. In the cells grown on glycerol, chloramphenicol inhibits the induction. The growth of the differentiated variant on fructose stops apparently due to the exhaustion of endogenous reserves which are necessary for maintaining the system of fructose uptake in the active state.     

Prevalence of alleles of polymorphic variants Leu33Pro and Leu66Arg gene ITGB3 among inhabitants of Siberia

The frequency of the polymorphic variant T196C (Leu33Pro, rs5918) of ITGB3 gene was studied in several groups of inhabitants of Siberia, including women with reproductive disorders (n = 186), patients with acute coronary syndrome (n = 330), and population control (n = 858). The frequency of the rare PLA2 allele among residents of Tomsk and Kemerovo was 14.7% and 15.0% respectively. There were no differences in the allele and genotype frequencies of polymorphic variant between patients with acute coronary syndrome and the control group (p = 0.925, p = 0.622). The highest frequency of abnormal PLA2 allele (22.1%) and the PLA2/PLA2 genotype (8.8%) was observed among women who had miscarried, which was significantly different from the frequency of this allele and genotype in the control group (14.7%, p = 0.017; 2.1%, p = 0.0009). Sequencing showed that all samples with the nonspecific band had the polymorphic rs5918 variant and rs36080296 mutations (T216G, Leu66Arg). The frequency of the rs36080296 mutation among the residents of Siberia was 0.51%. Among the women with reproductive disorders, the frequency of rs36080296 was 2.7%, while in the group who suffered from miscarriages, it was 4.4%; this was different from the frequency in the control group (0.08%, p = 0.2 × 10^?6). The accumulation of mutations was also observed among men with acute coronary syndrome (0.6%), but the differences from the control group (0%) had no statistical significance. Thus, the rs36080296 mutation may be a factor in predisposition to miscarriage, especially in combination with the PLAII allele. In addition, the rs36080296 variant among men may be associated with acute cor onary syndrome, which requires further study.