Search

Background: Juvenile hormones (JH) regulate development and reproductive maturation in insects. JHs are synthesized through the mevalonate pathway (MVAP), an ancient metabolic pathway present in the three domains of life. Mevalonate kinase (MVK) is a key enzyme in the MVAP. MVK catalyzes the synthesis of phosphomevalonate (PM) by transferring the γ-phosphoryl group from ATP to the C5 hydroxyl oxygen of mevalonic acid (MA). Despite the importance of MVKs, these enzymes have been poorly characterized in insects., Results: We functionally characterized an Aedes aegypti MVK (AaMVK) expressed in the corpora allata (CA) of the mosquito. AaMVK displayed its activity in the presence of metal cofactors. Different nucleotides were used by AaMVK as phosphoryl donors. In the presence of Mg(2+), the enzyme has higher affinity for MA than ATP. The activity of AaMVK was regulated by feedback inhibition from long-chain isoprenoids, such as geranyl diphosphate (GPP) and farnesyl diphosphate (FPP)., Conclusions: AaMVK exhibited efficient inhibition by GPP and FPP (Ki less than 1 μM), and none by isopentenyl pyrophosphate (IPP) and dimethyl allyl pyrophosphate (DPPM). These results suggest that GPP and FPP might act as physiological inhibitors in the synthesis of isoprenoids in the CA of mosquitoes. Changing MVK activity can alter the flux of precursors and therefore regulate juvenile hormone biosynthesis.

We herein report an extremely rare case of a patient with IgD-lambda positive multiple myeloma presenting with myelomatous pleural effusion and ascites. A 58-year-old man visited our hospital with dyspnea as his initial symptom. His chest radiograph findings on admission revealed a left pleural effusion, and later, bilateral involvement. Computed tomography (CT) of the chest showed a paraspinal tumor with extension from the upper mediastinum to the abdomen. The cytological examination demonstrated myeloma cells in the pleural effusion and ascites, and histologically, in the pleura, an abdominal subcutaneous tumor and bone was observed. The pleural effusion was an exudate and slightly bloody. The ADA was 70 IU/L. Pleural effusion accompanying myeloma or primary pleural myeloma is very rare and, furthermore, the extremely rare findings of both myeloma cells in the ascites (although the ascites was mainly caused by liver cirrhosis) and a high ADA activity in the pleural fluid were also observed in this case.

Strains of Drosophila melanogaster homozygous for either the AdhF or the AdhS allele were kept on food supplemented with ethanol for 20 generations. These strains (FE and SE) were tested for tolerance to ethanol and compared with control strains (FN and SN). The E strains showed increased tolerance to ethanol both in the adult and in the juvenile life stages. In adults the increase in tolerance was not accompanied by an increase in overall ADH activity. However, there were changes in the distribution of ADH over the body parts. Flies of the FE strain possessed significantly more ADH in the abdomen, compared with FN. Another set of FN and SN populations were started both on standard food and on ethanol food with reduced yeast concentrations. After 9 months ADH activities were determined in flies from these populations which had been placed on three different media: the food the populations had been kept on, regular food and regular food supplemented with ethanol. The phenotypic effects of yeast reduction on ADH activity were considerably, but longterm genetic effects were limited.

1. Optimum conditions were established for determining the activities of the NADP(+)-linked enzymes, glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase and isocitrate dehydrogenase, in mosquito tissues. 2. The activity of each dehydrogenase was determined in samples of mosquitoes of different ages throughout the life-span. The specific-activity curves attained maximal values in the pupal or early adult period. From these maxima an 81% decrease in glucose 6-phosphate-dehydrogenase and 67% decrease in 6-phosphogluconate-dehydrogenase activities occurred after the tenth day of adult life; a 77% decrease in isocitrate-dehydrogenase activity occurred before the fifth day. 3. The activity differences were found in different body regions as well as in whole organisms. 4. Starvation of the larva or adult did not result in decreases in enzyme activity. 5. These findings support the hypothesis that the activities of enzymes that form NADPH are related to the biosynthetic activity, for the enzyme activities increased during the period of cellular growth and decreased during the aging period.

Phospholipase B has been found in the mosquito Culex pipiens fatigans, and some of its properties have been studied. The enzyme had a high optimum temperature (45 degrees C) and broad alkaline pH optimum (8-9). It was inactive toward diacylphospholipids, and hydrolyzed lysolecithin at a higher rate than lysophosphatidyl ethanolamine. The enzyme was heat labile, but lysolecithin protected it against heat inactivation. Phosphatidyl ethanolamine, phosphatidyl choline, deoxycholate, Fe(+++), and Hg(++) inhibited the enzyme markedly. The enzyme was present mainly in larvae; little enzyme activity was detected in pupae or adults. The total and specific activities were highest in IV instar (6 day) and I instar (1st day) larvae, respectively. It was localized in the microsomal fraction and was distributed mainly in the abdomen and thorax of the insect. The enzyme was present at much higher levels of activity in larvae of the mosquitoes Anopheles stephensi and Aedes aegypti.