Comparative development of Brugia pahangi and variation in acid hydrolase enzyme titers in.

The development of the filarial nematode Brugia pahangi was monitored and compared in susceptible (BLACK EYE) and refractory (ROCK) strains of Aedes aegypti. Simultaneously, the activities of acid phosphatase, beta-glucuronidase, alpha-glucosidase, and N-acetyl-beta-glucosaminidase were measured. Three- to five-day-old females of both strains were fed on infected and uninfected clawed jirds (Meriones unguiculatus) then dissected or homogenized at 2 h, at 24-h intervals for 5 days, and at 8 and 10 days after treatment. Enzyme activities were assayed by a fluorometric procedure. The susceptible strain maintained an 80% infection and 18.6 larvae/mosquito over the 10-day period. In contrast, the refractory strain was initially 33% infected and had a mean of 4.9 larvae/mosquito and this decreased to 20% by 3 days, and to 3% with a mean of 0.33 larvae/mosquito at 10 days. Significantly higher acid phosphatase and beta-glucuronidase activities were observed in the refractory strain at specific time intervals after infection. Alpha-glucosidase and N-acetyl-beta-glucosaminidase were highly variable among strains and according to infection status. Analysis of the results of this study suggests that certain acid hydrolase enzymes could be involved in the elimination of B. pahangi in refractory strains of Ae. aegypti and could be used to monitor biochemical changes in response to filarial nematode infections in certain mosquito populations.

Reduction in susceptibility to Brugia malayi of F2 progeny of Aedes togoi treated with ethyl methanesulfonate.

The susceptibility to Brugia malayi infection was tested in F2 female progeny derived from male and female Aedes togoi treated with ethyl methanesulfonate (EMS). Three-day-old males and females were treated with 0.025, 0.050, and 0.075, 0.10, 0.15, or 0.20% EMS by allowing them to feed for 5 days on sugar cubes containing EMS and then mated at random. Percentage of susceptibility and mean number of infective larvae (L3) in F2 females were analyzed over a 2-wk period. Reductions in susceptibility were significant in the F2 populations arising from the 3 highest EMS concentrations. F2 infections were reduced by 80%, indicating that EMS-induced mutations affect loci associated with filarial nematode susceptibility.

Variation in acid hydrolase enzyme titers in different developmental stages of Aedes togoi.

Genetic mechanisms of filarial nematode susceptibility were studied in Aedes togoi. Acid hydrolases may play an important role in this process, including humoral or cell-mediated defenses. Levels of acid phosphatase, alpha-glucosidase, beta-glucuronidase, and N-acetyl-beta-glucosaminidase were determined for 1st- and 4th-instar larvae, male and female pupae, and 1- and 7-day-old adults using fluorometric and colorimetric assays. Acid phosphatase activity was highest in 1-day-old adults, moderate in larvae and pupae, and lowest in 7-day-old adults. Female 7-day-old adults had significantly higher levels than males of the same age. Moderate levels of alpha-glucosidase were found in larvae, with progressive increases in activity from pupae to 7-day-old adults. Levels in male pupae and 1-day-old males were higher than in females, but activity was twice as high in 7-day-old females. Activity of beta-glucuronidase was greater in adults, with females showing a 2-fold higher level than males at 7 days. In contrast, N-acetyl-beta-glucosaminidase activity was highest in 1st- and 4th-instar larvae and 1-day-old males and females. Activity also was significantly higher in male pupae, slightly greater in 1-day-old males, but twice as high in 7-day-old females when compared to males of the same age. Results showed significant changes and variation in acid hydrolase enzyme titers in the different life stages of Ae. togoi. These and other specific acid hydrolases could prove effective in monitoring biochemical and genetic changes in mosquito populations.

Reduction in the susceptibility of Aedes aegypti to Brugia malayi infection after treatment with ethyl methanesulfonate.

The susceptibility to Brugia malayi infections of F2 and F4 progenies of Aedes aegypti (Black Eye strain) treated with ethyl methanesulfonate (EMS) was tested. Both 3-day-old males and females were treated with 0.025, 0.050, 0.075 and 0.10% EMS. Control and treated females were then mated with normal or treated males to recover F1 progeny. F2 offspring were derived from sibling intercrosses, and 3 lines were established by further intercross matings to generate the F4. Susceptibility in the 0.025, 0.050, 0.075 and 0.10% EMS F2s was reduced by 13, 12, 4 and 25%, respectively. The 0.025% and 0.050% EMS F2 females showed a 29 to 39% decrease in mean L3 numbers. At 0.075 and 0.10% EMS, mean L3 numbers decreased by 0.8 and 71%, respectively. The F4 populations gave overall infections of 65, 56 and 22% for the control, 0.25 and 0.10% EMS lines, respectively. Mean L3s were reduced by 24 and 77%, respectively, in the 0.025 and 0.10% F4 EMS-selected populations.

In situ noradrenaline-induced stimulation of dog thyrotrophic secretion.

Anterior pituitary microinfusions of noradrenaline in the dog causes a significant release of TSH while adrenaline and dopamine do not.