A system for studying evolution of life-like virtual organisms.

Background: Fitness landscapes, the dependences of fitness on the genotype, are of critical importance for the evolution of living beings. Unfortunately, fitness landscapes that are relevant to the evolution of complex biological functions are very poorly known. As a result, the existing theory of evolution is mostly based on postulated fitness landscapes, which diminishes its usefulness.

Conservation of structure and expression of the trithorax gene between Drosophila virilis and Drosophila melanogaster.

The Drosophila melanogaster trithorax gene encodes several large RNAs which are expressed in complex patterns in the embryo. The D. virilis trithorax gene was isolated and sequenced.

The Drosophila trithorax gene encodes a chromosomal protein and directly regulates the region-specific homeotic gene fork head.

The activity of the Drosophila gene trithorax is required to maintain the proper spatial pattern of expression of multiple homeotic genes of the Bithorax and Antennapedia complexes, trithorax encodes two large protein isoforms of > 400 kD. We have detected its products at 16 discrete sites on larval salivary gland polytene chromosomes, 12 of which colocalize with binding sites of several Polycomb group proteins. The intensity of trithorax protein binding is strongly decreased in larvae carrying mutations in another trithorax group gene ash-1, and in the Polycomb group gene pco/E(z).

The bithorax complex is regulated by trithorax earlier during Drosophila embryogenesis than is the Antennapedia complex, correlating with a bithorax-like expression pattern of distinct early trithorax transcripts.

The trithorax gene is required throughout development to maintain expression of homeotic genes of the bithorax and Antennapedia complexes. We determined complete structures of maternal and zygotic alternatively spliced trithorax transcripts, and found that two RNA isoforms are expressed in a surprising manner in the early embryo. At syncytial blastoderm their expression is confined to the ventral region fated to become mesoderm.

Cloning and analysis of the mobile element gypsy from D. virilis.

The homologue of the Drosophila melanogaster mobile element gypsy was cloned from the distantly related species D. virilis. It has three ORFs highly homologous to those of the element from D.