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M J Klowden

Publications and source records attributed to M J Klowden.

9 recordsLinked to original sources
PubMed1992

A bioassay for cobra cardiotoxin activity using semi-isolated cockroach heart.

A semi-isolated cockroach heart preparation was used to rapidly determine the activity of cobra cardiotoxin, monitored as a direct response on heart rate. This preparation produced a dose-response curve in the presence of active cardiotoxin and demonstrated that cardiotoxin retained its biological activity after boiling, although cardiotoxin activity was destroyed by heating in the presence of dithiothreitol. Experiments that cross-linked radiolabeled cardiotoxin to solubilized cockroach heart membranes suggested that cardiotoxin bound specifically to a 59,000 mol. wt membrane protein in this tissue.

Animals↗
PubMed1992

Reproductive and metabolic differences between Aedes aegypti and Ae. albopictus (Diptera: Culicidae).

Aedes albopictus (Skuse) females were more likely to develop eggs after they ingested small blood meals than were Aedes aegypti (L.) when both species were maintained under the same suboptimal adult nutritional regimen. The longevity of adult female Ae. albopictus under conditions of starvation was also significantly greater than that of Ae. aegypti. Analyses of total body proteins, lipids, and glycogen indicated that the increased reproductive efficiency of Ae. albopictus may be a result of its greater reserves accumulated during a longer larval period.

Aedes↗
PubMed1992

Sublethal effects of larval methoprene exposure on adult mosquito longevity.

Larvae of Aedes aegypti were exposed to sublethal concentrations of the insect growth regulator, methoprene, and the glycogen content of pupae and surviving adults was compared and effects on adult longevity determined. The glycogen reserves in both male and female Ae. aegypti pupae were significantly reduced as a result of methoprene exposure. The longevity of adult females was also significantly reduced, but exposure affected neither the longevity nor the glycogen content of adult males. Adult sugar feeding increased the amount of glycogen in both treated and control females. The reduced longevity of adult females from larval methoprene treatment appeared not to be directly related to reduced glycogen, but rather reflected neuroendocrine abnormalities induced by this juvenile hormone analogue.

Aedes↗
PubMed1978

Blood meal size as a factor affecting continued host-seeking by Aedes aegypti (L.).

The effect of ingested blood on the host-seeking response of two strains of Aedes aegypti was examined. Using an olfactometer, females fed partial blood meals were scored for host-seeking behavior within 1 h, and their blood meal sizes were measured chemically immediately afterwards. The suppression of host-seeking within 1 h after a blood meal appears to be caused by abdominal distention from ingested blood. Mosquitoes of either strain were attracted to a host when the blood meal size was less than 2.5 microliter; above this threshold there was a sharp decline in the tendency to respond. Small mosquitoes resulting from a low larval diet had a lower threshold, and were more likely to cease host-seeking after a small blood meal. Multiple feeding within a single gonotrophic cycle may result if mosquitoes take small blood meals which are insufficient to terminate host-seeking. Partial meals and reduced feeding success of mosquitoes can result from defensive host behavior, which in the laboratory rat was shown to increase at high mosquito densities.

Aedes↗
PubMed1977

Effects of antibiotics on the survival of Salmonella in the American cockroach.

The faecal survival of Salmonella typhimurium orally administered to restrained American cockroaches maintained on an antibiotic diet was investigated. Significant reductions in median numbers of total aerobic faecal microorganisms were noted in insects fed antibiotics daily, and when Salmonella was introduced to this modified micro-environment, it persisted for 44 days in all specimens. Multiplication of the pathogen was also observed in these insects, with numbers often exceeding 10(3) times that of the initial input. This differs significantly from our previous results showing that the pathogen is unable to multiply in conventional cockroaches. Attempts to restore the normal flora by feeding a faecal suspension from untreated cockroaches resulted in a decrease in numbers of Salmonella excreted, but did not result in their elimination. Carcasses of infected cockroaches retained viable Salmonella for at least 60 days post mortem, or 104 days after the infective meal.

Administration, Oral↗
PubMed1976

Salmonella in the American cockroach: evaluation of vector potential through dosed feeding experiments.

Restrained American cockroaches, Periplaneta americana L., were fed graded doses of Salmonella typhimurium ranging from 1-6 X 10(3) to 2-0 X 10(6), and their faeces assayed daily for the pathogen. Only 4 specimens out of 117 demonstrated multiplication of salmonellas, which was unrelated to size of input. When data of persistence regardless of actual numbers were expressed as percentage Salmonella-positive faecal-days, and these transformed to probits, a graph of percentage-positive faecal-days versus log dose allowed a calculation of the CD 50, or contaminative dose required for 50% of the faecal-days to be infective. The CD 50 for this cockroach species was 1-4 X 10(6) Salmonella.

Animals↗