ABSTRACT
Aim: Effect of gamma irradiation on genomic disorder in sesame are scanty. The present study was undertaken to evaluate the mutagenic effects of gamma rays on different parameters in two popular cultivars of sesame, Roma and Tilottama. Methodology: Seeds of these two cultivars were irradiated with five doses of gamma rays: (250, 300, 350, 400, and 450 Gy) at BARC, Trombay and were sown (along with the un-irradiated control) during March 2015 in a split plot design with 3 replications keeping row to row and plant to plant distance at 30 cm and 10 cm, respectively to determine mutagen sensitivity with regard to pollen fertility (%), germination (%) and seedling height (cm), root-shoot length (cm), plant survival (%) at maturity in M1 generation. To study mutability, four to five capsules from each M1 plants in all the treatments were collected separately to give rise the M2 generation. Individual plant progeny rows were sown in M2 during March 2016. ID50 was determined by probit analysis for germination, shoot-root length and plant survival. Since the dose requirement for pollen fertility is very high, ID30 was calculated instead of ID50 value. Results: It was observed that with increasing doses of gamma rays, the response of all characters decreased significantly and followed a linear relationship in both varieties. The root system was more profound to gamma rays than the shoot. Chlorophyll mutations showed independent response to different doses of gamma rays as they occurred in random. The mutability of genotype Roma induced with different doses of gamma rays was higher than that of Tilottama. Interpretation: Due to saturation in the mutational actions, response of characters decreased with increase in gamma ray doses but magnitudes of effect differed between genotypes. The cultivar Tilottama was found to be more sensitive than Roma.
ABSTRACT
Coronary artery disease (CAD) is a multifactorial disease caused by the interplay of environmental risk factors with multiple predisposing genes. The present study was undertaken to evaluate the role of DNA repair efficiency and oxidative stress and antioxidant status in CAD patients. Malonaldehyde (MDA), which is an indicator of oxidative stress, and mean break per cell (b/c) values, which is an indicator of decreased DNA repair efficiency, were found to be significantly increased in patients compared to normal controls (P<0.05) whereas ascorbic acid and GSH were found to be lower among patients than the control group. It has been found that elevated oxidative stress decreased antioxidant level and decreased DNA repair efficiency can contribute to the development of CAD. This study also showed that high MDA, low ascorbic acid and GSH were significantly associated with high b/c value.
ABSTRACT
Ribonucleotide reductase (RNR) of the yeast Saccharomyces cerevisiae is a tetrameric protein complex, consisting of two large and two small subunits. The small subunits Y2 and Y4 form a heterodimer and are encoded by yeast genes RNR2 and RNR4, respectively. Loss of Y4 in yeast mutant rnr4delta can be compensated for by up-regulated expression of Y2, and the formation of a small subunit Y2Y2 homodimer that allows for a partially functional RNR. However, rnr4delta mutants exhibit slower growth than wild-type (WT) cells and are sensitive to many mutagens, amongst them UVC and photo-activated mono- and bi-functional psoralens. Cells of the haploid rnr4delta mutant also show a 3- to 4-fold higher sensitivity to the oxidative stress-inducing chemical stannous chloride than those of the isogenic WT. Both strains acquired increased resistance to SnCl2 with age of culture, i.e., 24-h cultures were more sensitive than cells grown for 2, 3, 4, and 5 days in liquid culture. However, the sensitivity factor of three to four (WT/mutant) did not change significantly. Cultures of the rnr4delta mutant in stationary phase of growth always showed higher frequency of budding cells (budding index around 0.5) than those of the corresponding WT (budding index <0.1), pointing to a delay of mitosis/cytokinesis.