Vital genes in the heterochromatin of chromosomes 2 and 3 of Drosophila melanogaster.
Heterochromatin has been traditionally regarded as a genomic wasteland, but in the last three decades extensive genetic and molecular studies have shown that this ubiquitous component of eukaryotic chromosomes may perform important biological functions. In D. melanogaster, about 30 genes that are essential for viability and/or fertility have been mapped to the heterochromatin of the major autosomes. Thus far, the known essential genes exhibit a peculiar molecular organization. They consist of single-copy exons, while their introns are comprised mainly of degenerate transposons. Moreover, about one hundred predicted genes that escaped previous genetic analyses have been associated with the proximal regions of chromosome arms but it remains to be determined how many of these genes are actually located within the heterochromatin. In this overview, we present available data on the mapping, molecular organization and function of known vital genes embedded in the heterochromatin of chromosomes 2 and 3. Repetitive loci, such as Responder and the ABO elements, which are also located in the heterochromatin of chromosome 2, are not discussed here because they have been reviewed in detail elsewhere.
Dimitri
Patrizio
P
Dipartimento di Genetica e Biologia Molecolare Charles Darwin Università La Sapienza, Piazzale A. Moro 5, 00185, Roma, Italy. patrizio.dimitri@uniroma1.it
Corradini
Nicoletta
N
Rossi
Fabrizio
F
Vernì
Fiammetta
F
Cenci
Giovanni
G
Belloni
Giorgio
G
Zhimulev
Igor F
IF
Koryakov
Dmitry E
DE
D000818:Animals; D002874:Chromosome Mapping; D004251:DNA Transposable Elements; D004331:Drosophila melanogaster / Q000235:genetics*; D015870:Gene Expression; D006570:Heterochromatin / Q000235:genetics*
D004251:DNA Transposable Elements; D006570:Heterochromatin