Molecular Biology Research Communications
Volume:3 Issue: 1, Mar 2014

The histone-like protein HU is the most-abundant DNA-binding protein in bacteria. The HU protein non-specifically binds and bends DNA as a hetero- or homodimer, and can participate in DNA supercoiling and DNA condensation. It also takes part in DNA functions such as replication, recombination, and repair. HU does not recognize any specific sequences but shows a certain degree of specificity to cruciform DNA and repair intermediates such as nick, gap, bulge, etc. To understand the features of HU binding to DNA and repair intermediates, a fast and easy HU protein purification method is required. Here we report a two-step purification procedure of HU from Halobacillus karajensis (the gram positive and moderately halophilic bacteria isolated from Karaj surface soil). The method of HU purification allows obtaining a pure non-tagged protein. Salting out and ion exchange chromatography were applied for purification, and the purified protein was identified by immunoblotting. Results showed that the molecular weight of the purified protein was approximately 11 kDa which is immunologically similar to the Bacillus subtilis HU protein (HBsu).

Most plants encounter stress such as drought and salinity that adversely affect growth, development and crop productivity. The expression of the gene glutathione-s-transferases (GST) extends throughout various protective mechanisms in plants and allows them to adapt to unfavorable environmental conditions. GSTF1 (the first phi GSTFs class) gene expression patterns in the wheat cultivars Mahuti and Alamut were studied under salt and ABA treatments using a qRT-PCR technique. Results showed that gene expression patterns were significantly different in these two cultivars. Data showed that in Mahuti, there was an increase of transcript accumulation under salt and ABA treatments at 3h, 10h and 72h respectively. In Alamut, however, the pattern of transcript accumulation was different; the maximum was at 3h. In contrast, there were no significant differences observed between the cultivars for GSTF1 gene expression profiles at three levels of NaCl concentration (50, 100, and 200 mM) or in ABA (Abscisic Acid) treatment. It is likely that difference of gene expression patterns between the cultivars (Mahuti as a salt tolerant cultivar and Alamut as a salt sensitive cultivar) is due to distinct signaling pathways which activate GSTF1 expression. Lack of a significant difference between the GSTF1 gene expression profile under salt and ABA treatments suggests that the GSTF1 gene is not induced by stress stimuli. Of course it is possible that other levels of NaCl and ABA treatments cause a change in the GSTF1 gene.

Even purified enzyme preparations are often heterogeneous. For example, preparations of aspartate aminotransferase or cytochrome oxidase can consist of several different forms of the enzyme. For this reason we consider how different the kinetics of the reactions catalysed by a mixture of forms of an enzyme must be to provide some indication of the characteristics of the species present. Based on the standard Michaelis-Menten model, we show that if the Michaelis constants (Km) of two isoforms differ by a factor of at least 20 the steady-state kinetics can be used to characterise the mixture. However, even if heterogeneity is reflected in the kinetic data, the proportions of the different forms of the enzyme cannot be estimated from the kinetic data alone. Consequently, the heterogeneity of enzyme preparations is rarely reflected in measurements of their steady-state kinetics unless the species present have significantly different kinetic properties. This has two implications: (1) it is difficult, but not impossible, to detect molecular heterogeneity using kinetic data and (2) even when it is possible, a considerable quantity of high quality data is required.

Myostatin or growth and differentiation factor 8 (GDF8), has been known as the factor causing double muscling phenotypes in which a series of mutations make the myostatin protein inactive, hence disabling it to regulate the deposition of muscle fibre. This phenotype happens with high frequency in a breed of sheep known as the Texel. Quantitative trait loci (QTL) studies show that a portion of the OAR2 that encompasses GDF8 has a major effect on muscular growth of Belgian Texel, on the muscling and fat depth in New Zealand Texel sires, and UK Texel and Charollais sheep. The functional polymorphism resides inside the GDF8 non-coding region. To date, there have been studies showing biallelic SNPs with significantly different allelic frequencies between hyper-muscled Texel and control animals including one in the 3''UTR (g.+6223G>A) and one in 2.5 kb upstream from the GDF8 transcription start site (g.-2449G>C). The GDF8 allele of the Texel sheep is characterized by one G to A transition in the 3''UTR, creating a target site for mir1 and mir206 which are highly expressed in skeletal muscles. This prevents myostatin gene translation, thus contributing to the double muscling of Texel sheep. Therefore, the GDF8 g. +6223A allele seems to be a causative variable increasing muscularity in the Texel rams and could be identified as a quantitative trait nucleotide.

In order to survey the evolutionary history and impact of historical events on the genetic structure of Iranian people, the HV2 region of 141 mtDNA sequences related to six Iranian populations were analyzed. Slight and non-significant FST distances among the Central-western Persian speaking populations of Iran testify to the common origin of these populations from one proto-population. Mismatch distribution suggests that this proto-Iranian population started to colonize Iran about 30000 years ago which is almost consistent with the timing of arrival and colonization of western Asia by the anatomically modern human. Star-like haplotype network structures, significant and negative Tajima’s D (D=-2.08, Ph=0.428) observed in Mashhad may indicated the presence of inbreeding, drift or bottleneck events. The application of Monmonier’s maximum differences algorithm revealed a geographic zone of genetic discontinuity between the Arab people of Khuzestan and rest of Iranian populations. Geographical factors, in cooperation with cultural/linguistic differences, are the main reasons for this differentiation. The lack of a sharp geographical or ethno-linguistic structure for mtDNA HV2 sequence diversity was statistically supported by AMOVA and Mantel (r=0.19, P<0.05) tests.

Most plants encounter stress such as drought and salinity that adversely affect growth, development and crop productivity. The expression of the gene glutathione-s-transferases (GST) extends throughout various protective mechanisms in plants and allows them to adapt to unfavorable environmental conditions. GSTF1 (the first phi GSTFs class) gene expression patterns in the wheat cultivars Mahuti and Alamut were studied under salt and ABA treatments using a qRT-PCR technique. Results showed that gene expression patterns were significantly different in these two cultivars. Data showed that in Mahuti, there was an increase of transcript accumulation under salt and ABA treatments at 3h, 10h and 72h respectively. In Alamut, however, the pattern of transcript accumulation was different; the maximum was at 3h. In contrast, there were no significant differences observed between the cultivars for GSTF1 gene expression profiles at three levels of NaCl concentration (50, 100, and 200 mM) or in ABA (Abscisic Acid) treatment. It is likely that difference of gene expression patterns between the cultivars (Mahuti as a salt tolerant cultivar and Alamut as a salt sensitive cultivar) is due to distinct signaling pathways which activate GSTF1 expression. Lack of a significant difference between the GSTF1 gene expression profile under salt and ABA treatments suggests that the GSTF1 gene is not induced by stress stimuli. Of course it is possible that other levels of NaCl and ABA treatments cause a change in the GSTF1 gene.