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C Bailly J P Catteau N Helbecque J L Bernier R Houssin C Denis J P Hénichart 《Journal of inorganic biochemistry》1987,31(3):211-220
A model incorporating the metal chelating moiety of bleomycin and an anilinoacridine ring able to intercalate in DNA has been synthesized. The copper(II) complex of that molecule has been studied using circular dichroism and electron spin resonance by comparison with bleomycin. The introduction of the anilinoacridine ring involves a modification in the geometry of the complex. A distortion of the square-pyramidal form (type II complex) gives rise to a type I complex in which the metallic atom is drawn out of the plane of the four square-planar ligands and displaced slightly towards the fifth ligand. 相似文献
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Microbiological Degradation of Malodorous Substances of Swine Waste under Aerobic Conditions 总被引:2,自引:1,他引:1 下载免费PDF全文
Denis Bourque Jean-Guy Bisaillon Rjean Beaudet M. Sylvestre Muhammad Ishaque Andr Morin 《Applied microbiology》1987,53(1):137-141
Phenol, p-cresol, and volatile fatty acids (VFA; acetic, propionic, isobutyric, butyric, isovaleric, and valeric acids) were used as odor indicators of swine waste. Aeration of the waste allowed the indigenous microorganisms to grow and degrade these malodorous substances. The time required for degradation of these substances varied according to the waste used, and it was not necessarily related to their concentrations. Using a minimal medium which contained one of the malodorous compounds as sole carbon source, we have selected from swine waste microorganisms that can grow in the medium. The majority of these microorganisms were able to degrade the same substrate when inoculated in sterilized swine waste but with an efficiency varying from one strain to the other. None of these strains was able to degrade all malodorous substances studied. Within 6 days of incubation these selected strains degraded the following: Acinetobacter calcoaceticus, phenol and all VFA; Alcaligenes faecalis, p-cresol and all VFA; Corynebacterium glutamicum and Micrococcus sp., phenol, p-cresol, and acetic and propionic acids; Arthrobacter flavescens, all VFA. On a laboratory scale, the massive inoculation of swine waste with C. glutamicum or Micrococcus sp. accelerated degradation of the malodorous substances. However, this effect was not observed with all of the various swine wastes tested. These results suggest that an efficient deodorization process of various swine wastes could be developed at the farm level based on the aerobic indigenous microflora of each waste. 相似文献
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Robert Cedergren B. Franz Lang Denis Gravel 《Origins of life and evolution of the biosphere》1988,18(3):299-305
Proposals that an RNA-based genetic system preceeded DNA, stem from the ability of RNA to store genetic information and to promote simple catalysis. However, to be a valid basis for the RNA world, RNA catalysis must demonstrate or be related to intrinsic chemical properties which could have existed in primordial times. We analyze this question by first classifying RNA catalysis and related processes according to their mechanism. We define: (A) thedisjunct nucleophile class which leads to 5-phosphates. These include Group I and II intron splicing, nuclear mRNA splicing and RNase P reactions. Although Group I introns and its excision mechanism is likely to have existed in primordial times, present-day examples have arisen independently in different phyla much more recently. Comparative methodology indicates that RNase P catalysis originated before the divergence of the major kingdoms. In addition, alldisjunct nucleophile reactions can be interrelated by a proposed mechanism involving a distant 2-OH nucleophile. (B) theconjunct nucleophile class leading to 3-phosphates. This class is composed of self-cleaving RNAs found in plant viruses and the newt. We propose that tRNA splicing is related to this mechanism rather than the previous one. The presence of introns in tRNA genes of eukaryotes and archaebacteria supports the idea that tRNA splicing predates the divergence of these cell types. 相似文献
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Pulmonary alveoler macrophages exposedto very short chrysotile asbestos fibers present a typical cytotoxic response: extracellular releases of lactate dehydrogenase and -galactosidase, and a decrease in cellular ATP content. The objective of this study was to determine if nicotinamide and 3-aminobenzamide, two inhibitors of the ADP-ribosyl transferase, could modify the in vitro toxicity of chrysotilee fibers. After 30 min of pre-exposure with each of the two inihibitors, pulmonary alveolar macrophage monolayers were concominantly exposed for 18 hours to 50g of fibers. It was observed that, in a dose-effect relationship (5 to 30 mM), nicotinamide was very effective in reducing the extracellular liberation of the marker enzymes. At 30 mM, the enzyme releases in the medium had returned to control values; the restoration of cell viability was confirmed by ATP levels. Up to 5 mM 3-aminobenzamide did not provide any protection against chrysotile cytotoxicity. Nicotinic acid, a structural analogue of nicotinamide, but not an inhibitor of the ADP-ribosyl transferase, also showed no protective effect. Nicotinamide and 3-aminobenzamide increased the intracellular NAD+ pools, respectively by 350% and 250%. However, with or without additives, the chrysotile fibers caused a constant and significant decrease in NAD+ levels (40–55 pmoles). These results suggest that the inhibition of the nuclear ADP-ribosyl transferase is not the major mechanism by which nicotinamide protects pulmonary alveolar macrophages against the chrysotile asbestos fibers.Abbreviations 3-AB
3-aminobenzamide
- ADPRT
ADP-ribosyl transferase
- -GAL
-galactosidase
- DTT
dithiothreitol
- FBS
fetal bovine serum
- FMN
flavin mononucleotide
- HEPES
N-2-hydroxyethyl piperazine-N-2-ethanesulfonic acid
- LDH
lactate dehydrogenase
- NAD+
nicotinamide adenine dinucleotide (oxidized form)
- NADH
nicotimide adenine dinucleotide (reduced forms)
- NADPH
nicotimide adenine dinucleotide phosphate (reduced form)
- NAM
nicotinamide
- NIC
nicotinic acid
- ORS
oxygen radical species
- PAM
pulmonary alveolar macrophages
- S.E.
standard error of the mean
- TAPS
tris (hydroxymethyl) methylamino-propane sulfonic acid
- TRIS
tris (hydroxymethyl) aminomethane
- VSF
very short chrysotile fibers 相似文献
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Synopsis Sea surface temperatures across Cabot Strait (Gulf of St. Lawrence) ranged from 6 to 9°C on June 3, 1989, but only from 3 to 5°C on June 2, 1990. Periods of peak commercial landings of mackerel in eastern Cape Breton Island extended from May 22 to June 3 in 1989, and from May 28 to June 2 in 1990. In late May 1990, Atlantic mackerel were captured with a purse-seiner during exploratory fishing in Cabot Strait; commercial quantities were caught in water as cold as 2.8°C. The presence of mackerel in water a full 4°C colder than its reported lower tolerance limit indicates that the development of the 7°C isotherm is not a requirement for the vernal appearing of mackerel. The overlap of the periods of peak commercial landings between 1989 and 1990, despite: marked differences in warming chronology, suggests that the movements of mackerel are not as closely linked to water temperature as previously reported. The fish's thermal preferences could be subordinate to their reproductive requirements at this stage of their spawning migration. 相似文献
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Denis Roy Pierre Chevalier Pierre Ward Luc Savoie 《Applied microbiology and biotechnology》1991,34(5):653-655
Summary The ability of Bifidobacterium infantis ATCC 27 920 to ferment glucose, galactose, lactose, melibiose and raffinose was investigated with respect to -galactosidase (-d-galactoside galactohydrolase, E.C. 3.2.1.22). The sugars were tested at three concentrations: 0.5, 1.0 and 2.0%. The growth of B. infantis was slower on glucose compared with the other sugars. The highest specific growth rate was observed on melibiose followed by lactose. High cell numbers could be rapidly obtained on galactose-containing sugars. For each carbohydrate, enzyme activity was maximal at the end of the exponential phase and the highest specific -galactosidase activities were recorded on the two -1,6 galactosaccharides (melibiose and raffinose: 3.0 and 4.5 nkat · 109 colony-forming units, respectively).Contribution no. 186 from the Food Research and Development Centre
Offprint requests to: D. Roy 相似文献