Quantitative analysis of the amount of larval serum protein-1 (LSP-1) synthesized by flies with different doses of the LSP-1 coding sequences.

Larval serum protein-1 (LSP-1) and LSP-2 are the major proteins of Drosophila larval serum. The amount of LSP-1 synthesized is strictly proportional to the number of LSP-1 genes present within the range 1-10. The normal number in female flies is 6. Flies with extreme amounts of LSP-1 were, by our criteria, as fit as the wild type. The ratio of LSP-2:LSP-1 was analyzed in 169 different stocks and was constant in 164 of these. The significantly different ratios in five stocks were all due to the lack of one of the LSP-1 gene products.