Genetic diversity of Azotobacter strains isolated from soils by amplified ribosomal DNA restriction analysis.

Strains of Azotobacter mediate in the nitrogen fixation process by reducing of N2 to ammonia. In this study, 50 strains were isolated from different rhizospheric soil in central Iran, by using soil paste-plate method. These strains were biochemically identified and characterized on differential LG medium based on morphological and physiological properties. Results obtained showed that identified strains were belonging to three species, namely A. chroococcum, A. vinelandii and A. beijernckii. In order to molecular analysis, the 16S rRNA gene was amplified using 27f and 1495r primers and PCR products were subsequently digested with RsaI, HpaII and HhaI. Cluster analysis based on amplified ribosomal DNA restriction analysis were revealed intraspecific polymorphism and differentiated strains into two mains clusters, clusters A and B. Cluster A strains were related to the A. vinelandii, whereas cluster B strains were related to the A. chroococcum and A. beijerinckii. The results show that amplified ribosomal DNA restriction analysis is a powerful and discriminatory tool for the identification of members of the genus Azotobacter.

Mir-55 inhibition can reduce cell proliferation and induce apoptosis in Jurkat (Acute T cell Leukemia) cell line.

BACKGROUND: MicroRNAs are small and non-coding RNA molecules with approximately 22 nt in length that cause inhibition of translation or degradation of mRNA. MiR-155 is a kind of molecule with different functions, such as its role in proliferation, apoptosis, inflammation, differentiation, and immunity. One of its best known functions is apoptosis that affects on caspase-3 activity. The main aim of this study was evaluation of miR-155 inhibition effect on cell proliferation and apoptosis induction in Jurkat cells. MATERIAL AND METHODS: In this study, Jurkat cells along with MTT assay were used for evaluation of sensitivity to varied concentrations of miR-155 inhibitor (25, 50 and 75 nmol). MiR-155 expression level was analyzed using the quantitative real-time polymerase chain reaction (QRT-PCR). Caspase-3 activity was measured by caspase-3 colorimetric activity assay kit. Unpaired t-test was applied for the analysis of MTT and apoptosis results. Probability of 5% was assumed as statistically significant. RESULTS: According to our results, the use of miR-155 inhibitor increased the activity of caspase-3 by 2 fold in 75 nmol concentration. In this research, we found that the proper increase of miR-155 inhibitor concentration can inhibit miR-155 and consequently increase caspase-3 activity and induce apoptosis in the Jurkat cells leading to cell death ultimately. CONCLUSIONS: Apoptosis induction by miRNAs activation or inhibition is probably one of the best and low risk ways of cell death induction in malignancies. Due to role of miR-155 in several cancer cells, it may be used as a therapeutic target in future.

Helicobacter pylori genotypes and types of gastritis in first-degree relatives of gastric cancer patients.

The frequency of Helicobacter pylori vacA alleles, cagA, and jhp0947 and their association with types and advanced forms of gastritis in 143 first-degree relatives of gastric cancer (GC) patients was assessed. The subjects included 64/143 with antral-predominant gastritis, 68/143 with pangastritis, and 11/143 with corpus-predominant gastritis, with or without atrophy or intestinal metaplasia (IM). Further classification included the severity of atrophy or IM. Group I (40/143) included the subjects with moderate-marked atrophy or IM, group II (58/143) those with no atrophy or IM, and group III (45/143) with mild atrophy or IM. The frequency of vacA s1 was 79.7%, vacA s2 20.3%, m1 49.7%, m2 50.3%, cagA 76.2%, and jhp0947 58%. The most prevalent combination was vacAs1 cagA (+) (65.7%) (P=0.001). Of the 143 subjects, 85 (59.4%) showed atrophy or IM, and 40/85 (47%) developed the moderate-marked atrophy or IM. No significant correlation was found between genotypes and the types of gastritis, non-atrophy, atrophy, or IM and severe forms of atrophy or IM (P>0.05). It is proposed that H. pylori genotype status might not be considered as an important determinant of the types and advanced forms of gastritis in the first-degree relatives of GC patients.