THE ALCOHOL-DEHYDROGENASE POLYMORPHISM IN NATURAL-POPULATIONS OF DROSOPHILA-MELANOGASTER - ADH ACTIVITY VARIATION RESTRICTION SITE POLYMORPHISM AND THE ADH CLINE

Alcohol dehydrogenase activity has been measured in 186 iso-second chr omosome lines - 104 from seven Australian populations and 82 from six Chinese populations. Restriction endonuclease variation in the Adh gen e region in these lines has previously been described (Jiang & Gibson, 1991). The mean ADH activity of Adh(F) and Adh(S) lines was significa ntly higher in the Chinese samples than in the Australian samples. In each population on both continents the mean activity of the Adh(F) lin es is significantly higher than that of the Adh(S) lines. Six lines ho mozygous for a thermostability variant, Adh(FChD) (detected in four of the Chinese populations), had intermediate levels of ADH activity and protein amount. In a subset of the lines with the highest and lowest levels of ADH, there was a correlation of 0.69 between ADH activity an d ADH CRM. None of the restriction site variants was consistently asso ciated with the amount of ADH activity. Associations between BamHI(-7. 2), the Adh polymorphism and ADH activity suggest that there are modif iers of ADH 5' to the gene. The deletion (0.2) at position -2.8 on the restriction map (Jiang & Gibson, 1991) was associated with increased levels of ADH activity in Adh(S) lines from China. Two unique insertio ns in the gene region were associated with low activity in Adh(F) line s and a null activity allele had a deletion removing most of exon 2. A single line with a duplication of a part of the adh coding region and of the 5' regulatory section had relatively high ADH activity. Consid ering all the data, the main factor affecting ADH activity levels in p opulations is the frequency of Adh(F).