Project Title: EXPLORATION OF GENE FUNCTION AND ORGANIZATION DURING DEVELOPMENTAL EVENTS

The study of developmental genetics is one of the profound pursuits of biology and a frontier area in which new paradigm of biology are likely to be uncovered. It involves exploration of gene functions and gene regulation during biological development in all organisms, from temperate phages to humans. Most developmental changes are mediated by process that operate at one level or another, of transcription control, without any preceding or accompanying structural change to the organization of the genetic material.

There are, however, a significant number of developmental changes that involve, at one level or another, structural changes to the genetic material of the particular cells in which the expression of the change is observed. These structural changes are often referred to as genetic rearrangements. Rearrangements of DNA and chromosomes generate diversity in both prokaryote and eukaryotes. These rearrangement have several consequences; they mat create new genes needed for expression in particular circumstances, they may change the function of existing sequences by placing them in mew regulatory situations, and they may be responsible for switching expression from one pre existing gene to another, all of which provides a mechanism for regulating gene expression.

Xer site-specific recombination functions in the normal segregation of multicopy plasmids and the bacterial chromosome of Escherichia coli. This recombination system converts circular dimmers of E.coli chromosomes and a multicopy plasmids to monomers, thereby helping chromosome and plasmid segregation at cell division. The proteins that mediate Xer site specific recombination include two related recombinases, XerC and XerD.

Recombination at cer, the Xer recombination site naturally present on plasmid ColE1, additionally requires two accessory proteins which are host encoded, the arginine repressor (ArgR) and aminopeptidaseA (PepA). Interestingly, both accessory protein are also involved in regulation of gene expression (the arginine and pyrimidine pathways respectively). As development of biological organism are controlled by the modulation of expression of genes, in depth understanding of the elements that control their expression is also necessary to facilitate successful site directed modification.

For the effective examination of these elements of model, an easily transformed transgenic system, is required. This will accelerate the transfer of the multiple gene constructs used to identify enhancer elements. Two tissue specific stylar promoters and plant viral promoter will be examined to identify enhancer and silencer elements. This will provide information on protein changes and DNA-protein interaction in gene expression prior to flowering.