John H. Williamson

Juvenile hormone-induced vitellogenesis in apterous4, a non-vitellogenic mutant in Drosophila melanogaster.

D. melanogaster females homozygous for the ap4 mutant synthesize yolk protein and circulate this protein in the haemolymph at concentrations not different from concentrations found in normal females. However, ap4 females deposit little or no yolk protein into developing oocytes. Topical application of a juvenile hormone analogue (JHA), ZR-515, stimulated sequestration of yolk protein by developing oocytes of ap4 females. JHA had no detectable effects on haemolymph concentrations of yolk protein in either normal or ap4 females nor on the protein profiles obtained from electrophoresis of haemolymph samples.

Synthesis and deposition of yolk protein in adult Drosophila melanogaster

Abstract Newly eclosed Drosophila melanogaster females contain only previtellogenic stage oocytes and no immunologically detectable female specific haemolymph protein. During the subsequent 48 hr the concentration of female specific protein in the haemolymph rises to a plateau value of 21 μg/μl; at this time yolk protein represents about one third of the total haemolymph protein in adult females. The first mature (stage 14) oocytes are observed at 48 hr post eclosion. The female specific haemolymph protein and the major protein from mature oocytes are electophoretically and immunologically the same or very similar. Injection of alpha amanitin into newly eclosed females inhibits the development of mature oocytes and the degree of inhibition depends on the age of the female at the time of injection. Phenocopies of non-vitellogenic mutants result when alpha amanitin is injected into newly eclosed females; after 36 hr post eclosion no visible inhibition of vitellogenesis (as observed morphologically at 72 hr post eclosion) can be produced by alpha amanitin.

A comparative study of the NADP-malic enzymes from Drosophila and chick liver

Abstract 1. 1. NADP-Malic enzyme (NADP-ME; l -malate:NADP + oxidoreductase (decarboxylating) EC 1.1.1.40) from Drosophila melanogaster has a mol wt of 266,000 and a subunit mol wt of 67,250 ± 3080. The amino acid composition of Drosophila NADP-ME is closely related to the NADP-MEs from pigeon liver, chick liver, rat liver and E. coli . 2. 2. Drosophila NADP-ME exhibits major malate oxidative decarboxylase and oxalacetate decarboxylase activities and minor pyruvate and oxalacetate reductase activities. 3. 3. The isoelectric point for Drosophila NADP-ME is 5.1 and the pH optimum for the oxidative decarboxylation of l -malate is 7.9. 4. 4. The malate oxidative decarboxylase activity of Drosophila NADP-ME is inhibited by NADPH, oxalacetate and ATP, but not pyruvate; the reverse reaction is inhibited by l -malate and NADP + . Drosophila NADP-ME is insensitive to N -ethylmaleimide at concentrations that strongly inhibit chick liver NADP-ME. 5. 5. Drosophila NADP-ME and chick liver NADP-ME are rapidly inactivated by palmityl-CoA, a process that is slowed by NADP + and Mn ⇔ .

Ontogeny, cell distribution, and the physiological role of NADP-malic enzyme in Drosophila melanogaster

NADP-malic enzyme (NADP-ME) (E.C. 1.1.1.40) is situated in the cytosol of Drosophila melanogaster. Both the tissue activity and CRM level of NADP-ME parallel changes in the dosage of a gene, Men+, located in region 87C2-3 to 87D1-2 of the third chromosome. The tissue activity of NADP-ME is very high in early third instar larvae, providing about 33% of the NADPH at this life stage. The tissue activity declines during pupal development but increases as the adult ages. The concentration of NADP-ME CRM and tissue activity are coordinately increased in third instar larvae by dietary carbohydrate and decreased by dietary lipid.

The effects of cinnamon on xanthine dehydrogenase, aldehyde oxidase, and pyridoxal oxidase activity during development in Drosophila melanogaster

Abstract The cinnamon (cin) eye color mutant of Drosophila melanogaster was characterized to determine biochemical correlations with another mutant, maroon-like . As with maroon-like, cinnamon flies lack three enzymatic activities: xanthine dehydrogenase, aldehyde oxidase, and pyridoxal oxidase. Xanthine dehydrogenase (XDH) is subject to a maternal effect in both mutants; i.e., mutant progeny of heterozygous mothers have XDH activity, resulting in wildtype eye color. However, the maternal effect is stronger in cinnamon than in maroon-like . Whereas maternally affected cinnamon show a large increase in XDH activity during larval stages, and XDH activity is still detectable after eclosion, the magnitude of increase in XDH activity is less in maroon-like , and activity is no longer detectable in second-day pupae and all later stages. The large increase in XDH activity in maternally affected cinnamon suggests that there is de novo synthesis of enzymatically active XDH during development in the absence of the cin + gene. Cinnamon is also unique in that maternally affected flies retain isoxanthopterin (IXP), the product of XDH activity. These flies appear to be deficient in some aspect of either pteridine metabolism or excretion.

Dietary modulation and histochemical localization of leucine aminopeptidase activity in Drosophila melanogaster larvae.

Abstract An isozyme of leucine aminopeptidase (LAP D) in Drosophila melanogaster larvae was localized in the midgut cells, midgut lumen, the peritrophic membrane and the lumen contents of the hind intestine by histochemical methods. Leucine aminopeptidase activity in larvae increased in response to increased concentrations of dietary protein. The implications of a LAP D dependence on a secretagogue stimulus are discussed.

Genetic and biochemical aspects of sucrase from Drosophila melanogaster

Isoelectrofocusing of abdominal extracts of Drosophila melanogaster revealed the existence of two forms of sucrase (E.C. 3.2.1.26). One form exhibited an isoelectric point of 4.63±0.02 while the other form exhibited an isoelectric point of 4.83±0.02. The localization of the structural gene for sucrase is proposed on the basis of enzyme determinations in a series of duplication- and deletion-bearing aneuploids. We suggest that the sucrase structural gene lies between 31CD and 31EF on the left arm of chromosome 2 and that the two forms of abdominal sucrase derive from a common protein coded for by a single sucrase gene designated Sucr+.

Ethyl methanesulfonate-induced mutants in the Y chromosome of Drosophila melanogaster.

Abstract Male sterility mutants have been induced in the Y chromosome by treatment with ethyl methanesulfonate. Complementation tests with deficient Y chromosome tester stocks revealed that many of the mutant Y chromosomes were deficient for more than one male fertility locus. Cytological analysis showed that in two cases of multiple deficiency the long arm of the Y chromosome was grossly reduced in size. Several of the mutant Y chromosomes were sensitive to the temperature at which males were reared, males being partially fertile when reared at 18° and sterile when reared at 25°.

6-Phosphogluconate dehydrogenase from Drosophila melanogaster. I. Purification and properties of the A isozyme.

Abstract6-Phosphogluconate dehyrogenase is evident at all developmental stages of Drosophila melanogaster. The activity level is highest in early third instar larvae and declines to a lower, but relatively constant, level at all later stages of development. The enzyme is localized in the cytosolic portion of the cell. The A-isozymic form of 6-phosphogluconate dehydrogenase was purified to homogeneity and has a molecular weight of 105,000. The enzyme is a dimer consisting of subunits with molecular weights of 55,000 and 53,000. For the oxidative decarboxylation of 6-phosphogluconate the Km for substrate is 81 µm while that for NADP+ is 22.3 µm. The optimum pH for activity is 7.8 while the optimum temperature is 37 C.

Differential characterization of two leucine aminopeptidases in Drosophila melanogaster

Two leucine aminopeptidases from Drosophila melanogaster larvae have been partially purified. The LAP A and D enzymes have similar biochemical characteristics including molecular weights of ≅280,000 daltons, Michaelis-Menten constants of ≅0.05 mM, associations with metal cofactors, and specificities toward natural and chromogenic substrates. They differ in their pH optima and spatial distributions. If the closely linked genes that code for these enzymes have resulted from a tandem gene duplication event, it is suggested that there has been subsequent evolutionary divergence. This would provide Drosophila larvae with two related, but functionally distinct enzymes.