Somatic cell genetics

The study of mechanisms of inheritance in animals and plants by using cells in culture. In such cells, chromosomes and genes can be reshuffled by parasexual methods, rather than having to depend upon the chromosome segregation and genetic recombination that occur during the meiotic cell divisions preceding gamete formation and sexual reproduction. Genetic analysis is concerned with the role of genes and chromosomes in the development and function of individuals and the evolution of species. Genetic analysis of complex multicellular organisms classically required multiple-generation families, and fairly large numbers of progeny of defined matings had to be scored. As a result, analysis of animals and plants with long generation times, small families, or lack of controlled matings was difficult and slow. Somatic cell genetics circumvents many of these limitations. It has enhanced the scope and speed of genetic analysis in higher plants and animals, especially when combined with the powerful techniques of molecular biology and the ability to generate fertile plants and animals from single cultured cells. With these methods, every gene in any species of interest can be identified and mapped to its position on a particular chromosome, its functions determined, and its evolutionary relationships to genes in other species revealed. Cross-species comparisons have provided essential insights into such poorly understood areas as embryonic differentiation and the development of complex nervous systems. See Embryonic differentiation, Molecular biology

Foreign genes (transgenes) can be introduced into somatic cells, which grow and differentiate into complete organisms whose sexual reproduction permits both the analysis of the effects of the introduced gene and the development of stocks with desirable characteristics. Transgenic plants have tremendous potential in the development of plants resistant to insects; to viral, fungal, or bacterial disease; and to environmental stress. Transgenic animals are generated in ever-increasing numbers because of their usefulness in studying cell differentiation, morphogenesis, and function. See Gene action, Genetic engineering, Genetics