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961.
An acridine-linked oligodeoxynucleotide targeted to the common 5' end of trypanosome mRNAs kills cultured parasites 总被引:12,自引:0,他引:12
Anti-messenger oligodeoxynucleotides covalently linked to an intercalating agent were tested for their ability to inhibit translation of Trypanosoma brucei mRNAs in a cell-free system. The sequence of these oligodeoxynucleotides was complementary to part of the 35-nucleotide (nt) sequence which is present at the 5' end of all trypanosome mRNAs (the so-called mini-exon sequence). In a rabbit reticulocyte lysate, a nonadeoxynucleotide linked to an acridine derivative, specifically inhibited protein synthesis from T. brucei mRNAs much more efficiently than unmodified oligodeoxynucleotides of similar length. These oligodeoxynucleotides were tested on cultured trypanosomes. The acridine-linked nonadeoxynucleotide had a lethal effect on the parasites. No effect was observed with the homologous unmodified 9-mer nor with those 9-mers linked to the acridine derivative which were not complementary to the mini-exon sequence. These effects are probably a result of hybrid formation between the anti-messenger and mini-exon sequence. Trypanocidal activity of the acridine-modified nonadeoxynucleotide is most likely due to (i) increased affinity for its target, (ii) improved resistance to 3' exonucleases, and (iii) promoted membrane penetration of living parasites. 相似文献
962.
A prospective randomised double blind study examined the effect of the antifibrinolytic drug tranexamic acid compared with placebo in 154 patients bleeding from verified benign lesions in the stomach or duodenum or both. Three out of 72 patients receiving tranexamic acid underwent emergency surgery compared with 15 out of 82 given placebo (p = 0.010). Nineteen patients receiving placebo rebled during their admission as compared with 10 in the active treatment group (p = 0.097). Blood transfusion requirements were significantly reduced by tranexamic acid (p = 0.018). Side effects occurred in six patients, of which an uncomplicated deep venous thrombosis was the most severe. Tranexamic acid reduces the blood transfusion requirement and need for emergency surgery in patients bleeding from a benign gastric or duodenal lesion. 相似文献
963.
In recent years the existence of a DNA-repair process in G2 has been proposed to explain the potentiating effects of DNA-repair inhibitors given in G2 on chromatid aberrations (CA) induced by S-dependent as well as S-independent DNA-damaging agents. In the present report, root-tip cells of Allium cepa were exposed to maleic hydrazide (MH) or mitomycin C (MMC) and post-treated in G2 with caffeine (Caff) and various inhibitors of DNA synthesis. No enhancement of chromosome damage was observed when Caff was present in G2, but hydroxyurea (HU) or 5-fluorodeoxyuridine (FdUrd) potentiated the frequencies of CA. A slight additional increase of CA frequencies was observed following treatment with Ara C and excess thymidine in G2. When MH-damaged cells were pulse-treated with Caff earlier during recovery, the yield of CA was enhanced. The earlier Caff was present following MH treatment, the stronger was the potentiation. 相似文献
964.
Chromosome aberrations and sister-chromatid exchanges (SCEs) were analyzed in short-term cultures of peripheral lymphocytes of 44 workers occupationally exposed to mancozeb during the production of the pesticide Novozir Mn80 and 30 control persons. The results suggest that mancozeb exposure was associated with a significant increase in the frequencies of cells with structural chromosome aberrations (2.07% vs. 1.10% in the controls), and the number of SCEs per cell (9.19 +/- 1.81 vs. 7.82 +/- 1.04 in the controls). 相似文献
965.
Irene A. Miller Steve Chatfield Gordon Dougan Leel Desilva Heather S. Joysey Carlos Hormaeche 《Molecular & general genetics : MGG》1989,215(2):312-316
Summary A cosmid gene bank of the virulent Salmonella typhimurium C5 was constructed in Escherichia coli K12. The bank was repackaged into bacteriophage heads and transduced into the semi-rough S. typhimurium strain AS68 which expresses the LamB receptor protein. Approximately 6000 ampicillin-resistant transductants were pooled and used as host for the propagation of bacteriophage P22. The P22 lysate was able to transduce cosmid recombinants to smooth strains of S. typhimurium and individual transductants were selected which complemented various S. typhimurium auxotrophic mutations. A stable mutation was introduced into the aroD gene of S. typhimurium C5. The resulting aroD
-
mutant, named CU038, was highly attenuated compared with the wild-type parent strain and BALB/c mice immunised orally with CU038 were well protected against challenge with the virulent C5 parental strain. Using the cosmid bank repackaged into bacteriophage P22 heads it was possible to isolate cosmid recombinants that could complement the aroD mutation of CU038 either by in vitro selection using minimal medium or in vivo selection for restoration of virulence in BALB/c mice. Repackaged P22 cosmid banks could provide a simple system for selecting in vivo for Salmonella virulence determinants. A Salmonella typhi strain harbouring mutations in aroA and aroD was constructed for potential use as a live oral typhoid vaccine in humans. 相似文献
966.
Ern? Zádor 《Molecular & general genetics : MGG》1989,218(3):487-490
Summary Acetylcholinesterase (AChE) is mainly membrane bound in the central nervous system (CNS) of larvae and in the head and thorax of adults of Drosophila melanogaster; it is mostly soluble in the larval carcass, the adult abdomen, similar to that of the embryos (Zador et al. 1986). The enzyme shows the same number of isozymes (four or five) in larvae and adults as in the head of the fly or in embryos (Zador et al. 1986). In the Df(3R)GE26/MKRS stock both the membrane bound and the soluble enzyme are at about half normal levels while in the Df(3R)Ace
HD1/MKRS stock this is true only for the membrane bound AChE. Therefore the effect of the above deficiencies in larvae and adults is consistent with that in embryos (Zador et al. 1986). In heat-sensitive combinations of certain Ace mutant alleles both the membrane bound and the soluble enzyme has reduced activity.Abbreviations AChE
acetylcholinesterase (acetylcholine acetyl hydrolase, EC 3.1.1.7)
- BAP
1,5-bis(allyldimethylammonium-phenyl)-pentan-3-one dibromide
- CNS
central nervous system 相似文献
967.
968.
Jay C. D. Hinton Julie M. Sidebotham Lizbeth J. Hyman Michel C. M. Pérombelon George P. C. Salmond 《Molecular & general genetics : MGG》1989,217(1):141-148
Summary The blackleg pathogen Erwinia carotovora subsp. atroseptica (Eca) causes an economically important disease of potatoes. We selected a genetically amenable Eca strain for the genetic analysis of virulence. Tn5 mutagenesis was used to generate nine mutants which exhibited reduced virulence (Rvi-) of strain SCRI1043. Following physiological characterisation, mutants were divided into three classes: (1) auxotrophs; (2) extracellular enzyme mutants; and (3) a growth rate mutant. The isolation of these Rvi- mutants has allowed us to consider some factors that affect Eca virulence. 相似文献
969.
970.
Summary We document activity field temperatures, daily activity patterns, and extent of thermoregulation in four species of Liolaemus lizards inhabiting at high altitude (above 3500 m) in the Andes of northern Chile. These four species have similar activity field temperature (Tb near 29°C) despite their being distributed at different altitudinal belts. However, conspicuous differences exist between higher-altitude (L. alticolor and L. jamesi) and lower-altitude (L. islugensis and L. ornatus) lizards regarding extent of thermoregulation and activity period. Some differences in morphology, behavior, and patterns of microhabitat occupancy are also apparent among these four species and are seemingly related to the thermal environment to which they are subjected. In comparison to eight low-altitude Liolaemus species in central Chile (Tb near 35°C) the four high-altitude species in northern Chile have lower activity field temperature. The latter is apparently due to the constraints imposed by the harsh Andean thermal environment, a hypothesis supported by the fact that high-altitude Liolaemus lizards under laboratory conditions demonstrate body temperatures that exceed by 5°C or more, those recorded in the field. 相似文献