Homeobox Genes DataBase

Drosophila Genes in Development: Proneural gene family

Scute

Function

scute is a proneural gene, one of the four genes that comprise the achaete-scute complex (AS-C). Like the achaete gene, scute plays a role in neurogenesis (see achaete-scute complex), but scute is also one of a number of factors on the X chromosome responsible for sex determination. Neither achaete nor lethal of scute can substitute for scute in sex determination, since only scute is transcribed early enough to function in this role.

Protein

Like Achaete, Scute has a central bHLH domain and a C-terminal acidic domain (Villares R., 1987).

Subcellular location

Nuclear

Expression Patterns

ac and sc transcripts are detected in a dynamic pattern from blastoderm (sc) or gastrula (ac) through stage 11 embryos. sc transcripts are abundant during the first half of embryonic development. They reappear at lower levels in third instar larval and pupal stages. In early embryos, sc transcripts are seen in somatic nuclei but not in the yolk nuclei. (Erickson J. W., 1993). They are present in clusters of cells on the ectoderm and internally near the mesoderm. They are expressed in most neurogenic regions. Their expression patterns are very similar except in stage 9 where sc is barely detectable and ac is expressed in four longitudinal rows of clusters. (Romani S., 1987)

sc transcripts are detected mainly in embryonic and pupal RNA. (Alonso M.C., 1988) sc protein is localized within the nuclei of proneural clusters. Clusters grow in number and intensity of staining until the sensory organ mother cell (SMC) becomes discernable due to its more intensely stained nucleus.The protein is transiently expressed in the SMCs, often at greater levels than the surrounding cells of the proneural cluster, but not in their progeny. (Skeath J.B., 1991) The sc protein disappears shortly before the SMC undergoes its first differential division. The pattern and timing of expression in specific clusters is discussed (Cubas P., 1991).

Observations of wing imaginal discs (larval sacs of cells that give rise to adult wings) reveal that achaete and scute are transcribed in a pattern that prefigures the future sites of neural elements, both ectopic and normal sensilla (Blair S.S., 1992).