GENETIC AND ENVIRONMENTAL FACTORS INVOLVED IN HUMAN MALE INFERTILITY: A REVIEW

As a World Health Organization (WHO) guidelines, infertility is the couple's inability to conceive after 2 years of regular unprotected intercourse. Theinvestigation in male infertility is assuming greater importance because approximately half of all infertility cases caused by male factors. Althoughprevious studies suggest that many cases with male infertility have a genetic and environmental etiology to the condition, and the majority of cases areidiopathic. About 10-20% of azoospermic patients are showing the microdeletion in Y-chromosome. In this deleted region, azoospermia factor (AZF)locus which is located in the Yq11 divided into the four regions as AZFa, AZFb, AZFc, and AZFd. In each of these regions a particular testicular histologyand candidate genes have been found. The deleted in azoospermia gene family is also the most frequently deleted in AZFc region. Recently, not only Ychromosome, but X chromosome and some autosomal genes are also found in respect to male infertility. Frequent attacks on the naked mitochondrialDNA of sperm will responsible for oxidative damage or mutation to the mitochondrial genome and lead to male infertility. The introduction ofmolecular techniques, such as intracytoplasmic sperm injection, genomics, proteomics, metabolamics, has provided great perception into the geneticsof infertility. Still our understanding to find a correlation between genotype and phenotype in male infertility remains limited.Keywords: Infertility, Azoospermia factor, Deleted in azoospermia, Mitochondrial DNA, Intracytoplasmic sperm injection, Genomics, Proteomics,Metabolamics

Gas Sensors Based on Semiconducting Metal Oxide One-Dimensional Nanostructures

This article provides a comprehensive review of recent (2008 and 2009) progress in gas sensors based on semiconducting metal oxide one-dimensional (1D) nanostructures. During last few years, gas sensors based on semiconducting oxide 1D nanostructures have been widely investigated. Additionally, modified or doped oxide nanowires/nanobelts have also been synthesized and used for gas sensor applications. Moreover, novel device structures such as electronic noses and low power consumption self-heated gas sensors have been invented and their gas sensing performance has also been evaluated. Finally, we also point out some challenges for future investigation and practical application