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.     

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.     

Effect of methotrexate on the leukemic cell cycle in mouse ascitic leukemia L1210]

In cells of L1210 ascite leukemia cells, methotrexate inhibited H3-thymidine incorporation, blocked shortly (during 4 hours) the G1 leads to S transition, and did not affect cells in G2-phase or in the late S phase. Almost half a cell population was degenerated and cells in S- and G1-phases were affected in equal proportion. This may suggest that methotrexate is not S-phase specific for cells of leukemia L1210. A simultaneous administration of vinblastine increases the antitumour effect of methotrexate. Cells in G2-phase constitute, presumably, a significant proportion of cells recovered after methotrexate administration. A comparison of the data obtained with literature evidence shows that in the sensitive (leukemia L1210) and resistant (acute mieloid leukemia of man) forms of leukemia, methotrexate affects cells that are in S-phase, whereas cells being in G1-phase are affected only when the sensitive tumours are treated.     

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.     

Sequence variants of LMP1 oncogene in patients with oral cavity tumors associated and not associated with Epstein-Barr virus

The role of Epstein-Barr virus (EBV), ubiquitous lymphotropic human herpesvirus 4, in etiology of nasopharyngeal carcinoma (NPC) has not been completely clarified. The mechanism of carcinogenesis in this disease (closely associated with EBV) is also unclear. The aim of the present study was to compare the structure of the LMP1 oncogene of EBV in isolates of the virus obtained from patients with two types of oral cavity tumors, including (a) associated (NPC) and (b) not associated (other tumors of the same anatomical region, OTOC) with EBV. A comparative analysis of the deductive C-terminal amino acid sequences of the LMP1 variants was carried out based on the LMP1 sequence data from samples of the tumor, blood, and oropharynx lavages from patients with NPC and OTOC. It was demonstrated that, in the compared groups of patients, all structural characteristics of LMP1 were close, and existing differences between the compared parameters were statistically insignificant. Thus, it was demonstrated for the first time that genetically related EBV strains with structurally similar LMP1 variants persist in patients with NPC and OTOC in Russia, which most likely reflects the polymorphism of EBV strains that circulate in the population. Based on the data obtained, it is possible to assume that the risk of the occurrence of NPC in NPC non-endemic world regions (including Russia) depends not so much on the EBV strain (and on the variant of the LMP1 that it contains) as on the genetic predisposition to the disease of individuals infected by this virus and the effect of other (still unknown) agents.