GSTM1 and GSTP1 polymorphisms and glutathione S-transferase activity: Iranian infertile men

"nBackground: Pi-GST and Mu-GST are subclasses of glutathione S-transferase that present on human sperm surface and play an important role against oxidative stress. Therefore, any defects in the enzyme activity may be associated with male infertility.In this study the polymorphisms of GSTM1 and GSTP1 in association with enzyme activity and sperm parameters were studied. "nMethods: This case-control study involved 95 men with oligoastenoteratozoospermia and 26 controls with normozoospermia. Semen analyses were carried out according to WHO guidelines. Blood DNA was extracted using salting out procedures. GSTM1 and GSTP1 polymorphisms gene were determined through PCR-RFLP and multiplex PCR, respectively. Finally, Glutathione S-transferase activity was measured. "nResults: Frequencies of GSTM1 null genotype in oligoastenoteratospermic and normospermic groups were 52.1% and 53.8% respectively. There were no statistically significant differences in sperm parameters and enzyme activity between GSTM1 null and positive genotypes in two groups. There were no statistically significant differences in glutathione S-transferase activity between oligoastenoteratospermia and normospermic groups (p>0.05). All the 121 men in this study had Ile/Ile genotypes at 105 codon of GSTP1. Frequency of normal homozygote (114Ala/Ala), heterozygote (114Ala/Val) and mutant homozygote (114Val/Val) genotypes in oligoastenoteratospermic group were 81.1%, 17.9% and 1.1% respectively but in the control group they were 88.5%, 11.5% and null. "nConclusions: Total glutathione S-transferase activity and sperm parameters were not affected by deficient Glutathione S-transferase activity in GSTM1 null genotype. Compensate activity of other sperm surface glutathione S-transferase isozymes, like GSTP1, may justify the cause

Determination of larval melanization in the moth, Mamestra brassicae, and the role of melanin in thermoregulation

Variability in the colour of lepidopteran larvae has been recorded in a broad range of species, yet little is known of its evolutionary significance, or whether it has a genetic basis. I assess the role of genes and environment in determining the degree of larval melanization in the moth, Mamestra brassicae, and examine functional aspects of larval pigmentation. In particular, whether melanization is of importance in thermoregulation, and whether larvae differing in melanization exhibit concurrent differences in size, rate of development, and fecundity. In the fourth and fifth instars, larval M. brassicae exhibit a continuous range of colour from pale green to black: a classification scheme is described to quantify this variation. Heritability (h2) was measured using regression of brood means against mid-parent values for 36 broods (2339 offspring), and was estimated to be 0.237 0.07 (SD) for fourth instar larvae and 0.421 0.10 (SD) for fifth instar larvae. However, environmental factors mediated development of larval colour: larvae were darker when reared at low temperature (12°C) compared to high (24°C). Direct measurement of larval temperatures using thermocouples inserted into the alimentary canal indicated that dark larvae absorbed more radiant heat, and thus under illumination consistently maintained a higher body temperature than pale larvae. Hence dark larvae are presumed to be at a selective advantage at low ambient temperatures, and increased melanization of larvae reared at low temperatures may be adaptive. I suggest that variation within natural populations may be maintained by fluctuating weather conditions. Dark larvae were found to be smaller, but developed more quickly than light larvae so that weight at pupation, time to pupation, and fecundity (measured by the number of fertile eggs produced) did not differ according to colour. Further studies are suggested to examine the influence of larval colour on thermoregulation, growth rates and predation in the field