The current focus of research is in the direction of improvement of life kinds, in the light of Genome analysis, Marker Aided Selection (MAS), functional aspects of gene and its expression.

Gene regulation forms an important component of research in molecular biology, with the present emphasis being on various regulatory mechanisms leading to the exploration of enhancer sequences, suppressor sequences and gene silencers for upregualtion, downregulation and switching off the genes, respectively, depending upon the requirement of gene functioning at different stages of life and its development. One of the emerging technologies in gene silencing is RNA interference (RNAi) which puts off genes not required or harmful to life. Such interference is possible either by exploiting the naturally available RNA in the living systems or synthetic interference molecules which mimic the natural mechanisms of gene silencing available. Such experiments are in progress to combat viral infections and cancers. This further signals the importance of RNA and other regulatory molecules in the overall regulation of genes during the development of organisms, leading to its application in the quantitative improvement of commercially important organisms or crops.

In the paper, "Isozymic Variation in Radish (Raphanus sativus L.) for Identifying Self-Incompatible Line", the authors, N A Ivy, M S Biswas, G Rasul, T Hossain and M A K Mian, have measured the diversity among 78 radish genotypes for esterase and peroxidase isozyme patterns, and the results indicate that zymotypes of higher frequency are the representative of less variation. The lower frequency of the germplasm in different zymotypes indicates higher variation among the genotypes.

In the paper, "Changes in the Pattern of Superoxide Dismutase (SOD) and Malate Dehydrogenase (MDH) in Response to Heat Stress Conditions in Wheat", the authors, Sameena Sheikh, R K Behl, Ashwani Kumar and A K Chabra, have studied the enzyme patterns of SOD and MDH that are implicated in thermotolerance during grain development stages. Their study reports enhanced activity and divergence in isozymes, revealing genotypic variability for functional stress tolerance mechanisms among genotypes.

In the next paper, "An Analysis of Genetic Diversity Among Indian Coldwater Fishes (Pisces: Cyprinidae) Using RAPD Markers", the authors, G K Sivaraman, A Barat, S Ali, N N Pandey, K D Joshi and P C Mahanta, have analyzed the genetic diversity among coldwater fish species and constructed phylogenetic relationships among them using RAPD markers. The study reveals T. putitora with S. richardsonii and Garra species withR. bola forming two distinct clusters.

In the paper, "Genetic Variability and Association for Floral, Quantitative and Quality Traits in Rice (Oriza sativa L.)", the authors, M Umadevi and P Veerabadhiran, have studied the genetic variability and correlation for 110 genotypes of rice. They estimated genotypic variance, phenotypic variance, genotypic coefficient of variation, phenotypic coefficient of variation, heritability in broad sense, genetic advance and association for grain yield with floral quantitative and quality characters which are effectively used in selection.

In the next paper, "Component Analysis of Upland Cotton (Gossypium hirsutum L.) in Different Environments", the authors, S K Kaushik and C J Kapoor, have analyzed additive, dominance and epistatic variance for number of sympodial branches per plant, using diallele analysis. This information is fundamental in the selection of appropriate breeding methodologies. The study recommends reciprocal recurrent selection for the improvement of the character under consideration because of different proportions of both additive and non-additive types of gene actions.

In the last paper, "Cryopreservation of Medicinal Plant Systems: Progress, Problems and Prospects", by the authors, P E Rajasekharan and R Prakashkumar, a thorough review has been made of cryopreservation of medicinal plants. The authors opine that the retention of biosynthetic potential of the retrieved cultures amply demonstrates the use of this technology for storage of rare, high alkaloid/secondary metabolites/medicines producing cell cultures for pharmaceutical purposes. The empirical studies in many species of medicinal plants showed promising results, and need-based protocols have to be evolved in the future.

Seventh article "Sperm Antigens: Potential Candidates for Male Immunocontraception," by authors D Madhaumayee, M Madhavi Lata, Manisha K Singh and V V Rao, who reviewed extensively the role of sperm antigen in male immuno-contraception. A focus is given on the development of human vaccine consisting of one or several gamete-associated immunogens, which offers an attractive approach to the growing global problem of over population.

V Venugopal Rao
Consulting Editor