Journal Article Use of total parasite DNA probes for the direct detection of Trypanosoma cruzi and Trypanosoma rangeli in domicilliary Rhodnius prolixus Get access S. Greig, S. Greig 1Department of Immunology, St George's Hospital Medical School, Cranmer Terrace, London, SW17 0RE, UK Search for other works by this author on: Oxford Academic PubMed Google Scholar F. Ashall, F. Ashall 2Depanment of Medical Protozoology, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK Search for other works by this author on: Oxford Academic PubMed Google Scholar L. Hudson L. Hudson 1Department of Immunology, St George's Hospital Medical School, Cranmer Terrace, London, SW17 0RE, UK Search for other works by this author on: Oxford Academic PubMed Google Scholar Transactions of The Royal Society of Tropical Medicine and Hygiene, Volume 84, Issue 1, January-February 1990, Pages 59–60, https://doi.org/10.1016/0035-9203(90)90382-O Published: 01 January 1990 Article history Received: 26 April 1989 Accepted: 11 July 1989 Published: 01 January 1990
SUMMARY Detergent extracts of Trypanosoma cruzi epimastigotes catalysed the hydrolysis of a range of amino-acyl and peptidyl p-nitro-anilides and aminomethylcoumarins. At least three enzymes were detected that cleave Z–Phe–Arg–MCA. Two of these were optimally active at alkaline pH, the other at pH 4·0. Of the two enzymes with alkaline pH optima, one was a cysteine peptidase and was unable to cleave Bz–Arg–MCA readily, whilst the other cleaved Bz–Arg–MCA and was inhibited by diisopropyl fluorophosphate. The acidic enzyme was similar to cathespin L of other eukayrotes with respect to its pH profile, substrate-specificity and inhibitor-sensitivity. Evidence was presented that epimastigotes contain a cysteine-type dipeptidyl aminopeptidase, one or more aminopeptidases, and a serine peptidase that cleaves Boc–Ala–Ala–pNA. Digitonin solubilization of the activities from cells supports the hypothesis that the cathespin L-like enzyme and the dipeptidyl aminopeptidase are lysosomal, whilst the Bz–Arg–MCA hydrolase, the aminopeptidases and the Boc–Ala–Ala–pNA serine peptidase are cytosolic.
A summary is not available for this content so a preview has been provided. Please use the Get access link above for information on how to access this content.
Previous studies demonstrated that in the transformed CHO (Chinese hamster ovary) cell a substantial part of the genome behaves as though its genes are sequestered from effective contact with soluble constituents of the intracellular fluid. The reverse transformation reaction, initiated by cAMP derivatives, causes this cell to regain the morphology, growth regulation, surface characteristics, and sensitivity of its DNA to digestion by DNase I that are characteristic of normal fibroblasts. In this paper we show that this action of cAMP is gene specific. In examination of 47 different genetic loci, some, like ribosomal RNA genes, are found to be sensitive to DNase I hydrolysis both in the absence and in the presence of cAMP; some are resistant under both conditions; and some are resistant in the untreated cell but become sensitive after cAMP treatment. Unlike other gene exposure reactions, which are irreversible and connected with differentiation phenomena, that produced by cAMP is readily reversed when the reagent is removed. A sequence of events is observed after cAMP treatment, the first of which is reorganization of the cytoskeleton. Afterwards, metabolic changes occur over periods as long as 72 hr. The cAMP-induced cytoskeleton-mediated gene exposure reaction appears to be an important genetic regulatory mechanism in mammalian cells and to have special implications for cancer.
A summary is not available for this content so a preview has been provided. Please use the Get access link above for information on how to access this content.
'%3e%3cpath fill='%23012169' d='M0 0v30h60V0z'/%3e%3cpath stroke='%23fff' stroke-width='6' d='m0 0 60 30m0-30L0 30'/%3e%3cpath stroke='%23C8102E' stroke-width='4' d='m0 0 60 30m0-30L0 30' clip-path='url(%23b)'/%3e%3cpath stroke='%23fff' stroke-width='10' d='M30 0v30M0 15h60'/%3e%3cpath stroke='%23C8102E' stroke-width='6' d='M30 0v30M0 15h60'/%3e%3c/g%3e%3c/svg%3e)
