Larval salivary glue protein heterosis and dosage compensation among the interspecific F1 hybrids of Drosophila nasuta nasuta and Drosophila nasuta albomicans

Reciprocal cross effects with respect to larval salivary secretory protein levels were studied in the interspecific fertile reciprocal hybrids by crossing Drosophila nasuta nasuta, and Drosophila nasuta albomicans. These proteins are produced copiously during the third larval instar stage and are believed to play a role in the attachment of pupa to the substratum prior to pupariation as well as in insect immunity. Quantitative variations were encountered among the reciprocal hybrids. Significant heterosis was observed between D. n. nasuta and the F₁ hybrid female of a cross between D. n. albomicans female and D. n. nasuta male (21.39%) while the F₁ hybrids of a cross between D. n. nasuta female and D. n. albomicans male showed a marginal increase (4.24%) from the mid parent level. The glue secretions were correlated to total cell number but independent of gland size. SDS PAGE revealed a considerable heterosis with respect to X-linked protein fractions. Here we report sex specific biochemical heterosis. However the X-linked fractions undergo dosage compensation in both parents and hybrids indicating strict regulatory control.