POPULATION GENETICS OF DROSOPHILA AMYLASE. I. GENETIC CONTROL OF TISSUE-SPECIFIC EXPRESSION IN D. PSEUDOOBSCURA

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Abstract
Drosophila pseudoobscura is polymorphic for tissue-specific expression of α-amylase in adult midguts. This enzyme is encoded by a single locus, Amy, on the third chroniosome. In this paper we show: (1) Up to about 12 days post-eclosion, the midgut activity patterns remain stable; after 12 days areas not showing activity previously begin to show activity. ThuS the genes controlling the expression of Amy are temporally acting. (2) Diet affects the quantitative, but not the qualitative, expression of Amy. (3) The expression of Amy in adult midguts is under genetic control. Selection for different frequencies of patterns is possible; realized heritabilities are 0.20 to 0.50. Partial linkage with third chromosome inversions has been demonstrated; the genes or elements controlling Amy expression are not, howevr, confined to the third chromosome. (4) The genetic elements controlling tissue-specific expression of amylase do not coordinately control the expression of five other "digestive-type" enzymes that were studied.—This polymophism appears to be analogous to that studied by ABRAHAM and DOANE (1978) in D. melanogaster, wherein they have mapped regulatory genes.