Characteristics of the endocrine system in Drosophila melanogaster 1 (2)gl mutants, differing in time of death]

A comparative study of the state of the endocrine system and one of the larval organs, the salivary gland, has been carried out in larvae homozygous for the 1(2)gl gene. They differ in time of death (death at the third larval instar--larval allele, and at the prepupal state--prepupal allele). It is shown that homozygotes for the larval and prepupal allele have underdeveloped prothoracal glands. Corpora allata in homozygotes for the larval allele does not differ from the norm. Corpora allata in homozygotes for the prepupal allele is decreased proportionally to the decrease of prothoracal glands. A decrease of gland size is due to a decrease of the volume of cell but not to their number; this decrease is accompanied by the decrease of their relative DNA content. Salivary glands in homozygotes are reduced and comprise 80% of the normal size in homozygotes for the prepupal allele and 50% for homozygotes for the larval allele. Polyteny level in the salivary gland nuclei is much decreased as compared with the normal level. DNA level is more reduced in larvae homozygous for the larval allele.