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The effect of inhibitors in vivo on protein synthesis and the amino acid pool in the sheep blowfly, Lucilia cuprina.

ABSTRACT: 1. The rates of detoxification of cycloheximide (33 mug/g fresh wt.), puromycin (167 mug/g fresh wt.) and actinomycin D (1 mug/g fresh wt.) were assessed in vivo on the basis of acid-insoluble [14C]leucine incorporation in the sheep blowfly, Lucilla cuprina; these were compared with quantitative estimates which took account not only of incorporation data but also of leucine pool size and turnover. Quantitatively, cycloheximide and puromycin were still at least 50% effective in inhibiting protein synthesis after 6.5 and 24.5h of exposure respectively, whereas values based only on incorporation data suggested that cycloheximide was 83% effective and puromycin completely ineffective after the respective periods. Quantitative estimates also showed that actinomycin D effectiveness increased with increasing exposure over 24.5h, in contrast with values based only on incorporation data, which suggested that it was completely ineffective after 24h.2. All inhibitors affected the dynamic state of the amino acid pool; there was a marked decrease in the rate of leucine-pool turnover as well as an increase in the half-life of leucine in the pool. 3. Inhibition of protein synthesis resulted in changes in leucine-pool size; the most pronounced increase occurred with cycloheximide and puromycin and the most pronounced decreases with actinomycin D. 4. Evidence is presented which suggests that proteolysis is functionally linked to protein synthesis, which determines its rate indirectly.

SUBMITTER: Campbell AJ

PROVIDER: S-EPMC1165730 | biostudies-other | 1975 Aug

REPOSITORIES: biostudies-other

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Histone deacetylase enzymes as drug targets for the control of the sheep blowfly, Lucilia cuprina.

Project description:The Australian sheep blowfly, Lucilia cuprina, is an ecto-parasite that causes significant economic losses in the sheep industry. Emerging resistance to insecticides used to protect sheep from this parasite is driving the search for new drugs that act via different mechanisms. Inhibitors of histone deacetylases (HDACs), enzymes essential for regulating eukaryotic gene transcription, are prospective new insecticides based on their capacity to kill human parasites. The blowfly genome was found here to contain five HDAC genes corresponding to human HDACs 1, 3, 4, 6 and 11. The catalytic domains of blowfly HDACs 1 and 3 have high sequence identity with corresponding human and other Dipteran insect HDACs (Musca domestica and Drosophila melanogaster). On the other hand, HDACs 4, 6 and 11 from the blowfly and the other Dipteran species showed up to 53% difference in catalytic domain amino acids from corresponding human sequences, suggesting the possibility of developing HDAC inhibitors specific for insects as desired for a commercial insecticide. Differences in transcription patterns for different blowfly HDACs through the life cycle, and between the sexes of adult flies, suggest different functions in regulating gene transcription within this organism and possibly different vulnerabilities. Data that supports HDACs as possible new insecticide targets is the finding that trichostatin A and suberoylanilide hydroxamic acid retarded growth of early instar blowfly larvae in vitro, and reduced the pupation rate. Trichostatin A was 8-fold less potent than the commercial insecticide cyromazine in inhibiting larval growth. Our results support further development of inhibitors of blowfly HDACs with selectivity over human and other mammalian HDACs as a new class of prospective insecticides for sheep blowfly.

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Insecticidal activities of histone deacetylase inhibitors against a dipteran parasite of sheep, Lucilia cuprina.

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A transgenic embryonic sexing system for the Australian sheep blow fly Lucilia cuprina.

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Evidence of a calcium-ion-transport system in mitochondria isolated from flight muscle of the developing sheep blowfly Lucilia cuprina.

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