Biologists at the University of California, San Diego have discovered in the roundworm C. elegans a new class of genes necessary for the normal development of the earliest stages of embryonic development in animals.
In the May issue of the journal Developmental Biology, the UCSD researchers report the discovery of a new class of genes that regulates the asymmetric division of the first cell in the developing embryo into an unequal sized pair of cells.
"The actual mechanisms by which this happens are not well understood," says Raffi V. Aroian, an assistant professor of biology at UCSD who headed the research. "By understanding more about the genes that regulate this process, we can provide more information about one of the key questions in developmental biology-how complex organisms such as humans develop from a single-celled embryo."
In normal embryos, the larger of these cells develops into the outer layers of an organism, such as its skin and nervous system, while the smaller of the two cells develops into the inner portions, such as its muscle, gut and reproductive organs. When one of the genes in this new class is defective, however, the absence of differences between the two cells prevents the differentiation necessary for development.
"If the asymmetrical division is screwed up, the embryo is never going to make it," says Akiko Tagawa, a graduate student and the lead author of the paper, which also includes Chad A. Rappleye, another graduate student working in Aroian's laboratory. "It quickly dies."
In addition, the cells containing these mutant genes are vulnerable to bursting and shriveling. This is due to the inability of the defective embryo's cell membranes to maintain the cell's osmotic pressure, which can produce an undesirable flood of fluids into or out of the cells.
The UCSD scientists have dubbed their new class pod genes-for polarity and osmotic defective genes-because mutations in them resu
Contact: Kim McDonald
University of California - San Diego