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The US National Human Genome Research Institute has allocated the first grants in a four-year project called modENCODE, which aims to identify all the functionally important elements in the genomes of the fruit fly Drosophila melanogaster and the roundworm Caenorhabditis elegans. modENCODE is part of a larger initiative, ENCODE, (EnCyclopaedia Of DNA Elements), that is working towards building a complete catalogue of these elements in humans. Functionally important elements include not just protein-coding genes but also regulatory sequences that control gene expression, genes encoding functional RNAs (which are also turning out to be important players in gene regulation), and sequences important for the structure and dynamics of chromosomes.

Past studies on the fruit fly and the worm have yielded a wealth of information on gene functions and properties that is also relevant to the much more complex human genome. The rationale behind modENCODE is that many of the functional elements identified in the genomes of the fly and the worm will turn out to be present and have similar properties in humans, but can be more easily studied and characterised in these simpler model organisms.