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31.
32.
Laboratory-scale reactors were used to watch aspects of biodegradation of wheat straw when supplemented with polysaccharidases (Czym) to increase the enzyme production of microorganisms involved during a composting process for mushroom production. Biochemical and biological parameters were tested both under aerobic and O2-limited conditions to assess degradability. These were measurement of released CO2 and NH3, determination of neutral detergent fibre content and cellulase activities from compost extract. The addition of Czym to decomposing straw had three consequences: (i) it supplied and released low quantities of readily available sugars; (ii) it increased the cellulase activities in the substrates; (iii) it increased the number of bacteria under aerobic conditions. The three effects were linked and the small quantity of sugars released by the addition of Czym may have acted as an activator of bacterial activities through an inductive mechanism.
Correspondence to: S. Libmond 相似文献
33.
Jacques Magdalou Sylvie Fournel-Gigleux Michael Pritchard Grard Siest 《Biology of the cell / under the auspices of the European Cell Biology Organization》1993,77(1):13-16
Summary— Peroxisome proliferators, despite their chemically unrelated structures, share the common property of being able to stimulate the glucuronidation of bilirubin in rodents and, probably, also in man. The aryloxycarboxylic acids (clofibric acid, fenofibrate, bezafibrate, ciprofibrate), tiadenol and probucol, all of which have hypolipidemic properties, as well as the fatty acid-like perfluorodecanoic acid all enhanced the expression of the UDP-glucuronosyltransferase (UGT) form involved in the conjugation of the pigment. This induction is manifested by an increase in the mRNA species encoding the protein with a subsequent increase in the neosynthesis of the corresponding protein in the endoplasmic reticulum. The induction process is concomitant with that of cytochrome P-450-IVA1 and cytosolic epoxide hydrolase, which, like bilirubin UGT, are mainly involved in the metabolism of endogenous substrates. With a series of carboxylic acids related to clofibric acid, it was possible to demonstrate that induction was mediated via specific interactions based on the physicochemical properties of the inducers. Until now, the molecular basis of induction of bilirubin UGT is not known. The peroxisome proliferators that possess a carboxyl group are good substrates of UGT, especially in man. The acylglucuronides formed are known for their instability and reactivity which could contribute to the toxicity encountered in some patients treated with the drugs. There is convincing evidence that UGT bilirubin does not catalyze the glucuronidation of these substances even if the two types of substrate form acylglucuronides. 相似文献
34.
Corine Vernet Joëlle Boretto Marie-Geneviève Mattéi Masahide Takahashi Lucinda J. W. Jack Ian H. Mather Sylvie Rouquier Pierre Pontarotti 《Journal of molecular evolution》1993,37(6):600-612
Summary During a search for novel coding sequences within the human MHC class I region (chromosome 6p21.3), we found an exon (named B30-2) coding for a 166-amino-acid peptide which is very similar to the C-terminal domain of several coding sequences: human 52-kD Sjögren's syndrome nuclear antigen A/Ro (SS-A/Ro) and ret finger protein (RFP), Xenopus nuclear factor 7 (XNF7), and bovine butyrophilin. The first three of these proteins share similarities over the whole length of the molecule whereas butyrophilin is similar in the C-terminal domain. The N-terminal domain of butyrophilin is similar to rat myelin/oligodendrocyte glycoprotein (MOG) and chicken B blood group system (B-G) protein. These domains are components of a new subfamily of the immunoglobulin superfamily (IgSF). Butyrophilin is thus a mosaic protein composed of the MOG/B-G Ig-like domain and the C-terminal domain of 52-kD SS-A/Ro, RFP, and XNF7 (1330-2-like domain). Moreover, in situ hybridization shows that RFP, butyrophilin, and MOG map to the human chromosome 6p2l.3-6p22 region and are thus close to the MHC class I genes. It is therefore possible that the butyrophilin gene is the product of an exon shuffling event which occurred between ancestors of the RFP and MOG genes. To our knowledge, this is the first example of the colocalization of a chimeric gene and its putative progenitors. Finally, regulatory protein T-lymphocyte 1 (Rpt-1) shares similarities with the N-terminal halves of RFP, 52-kD SS-A/Ro, and XNF7, but not with the B30-2-like domain. We show that the ancestral Rpt-l gene evolved by overprinting.
Correspondence to: P. Pontarotti 相似文献
35.
Sylvie Nadeau Martin Bilodeau Alain Delisle Witold Chmielewski A.Bertrand Arsenault Denis Gravel 《Journal of electromyography and kinesiology》1993,3(4):205-213
Different behaviours of the EMG power spectrum across increasing force levels have been reported for the masseter muscle. A factor that could explain these different behaviours may be the type of contraction used, as was recently shown for certain upper limb muscles5. The purpose of this study was to compare, between two types of isometric contractions, the behaviour of EMG power spectrum statistics (median frequency (MF) and mean power frequency (MPF)) obtained across increasing force levels. Ten women exerted, while biting in the intercuspal position, three 5 s ramp contractions that increased linearly from 0 to 100% of the maximal voluntary contraction (MVC). They also completed three step contractions (constant EMG amplitude) at each of the following levels: 20, 40, 60 and 80% MVC. EMG signals from the masseter muscle were recorded with miniature surface electrodes. The RMS, as well as the MPF and MF of the power spectrum were calculated at 20, 40, 60 and 80% MVC for each type of contraction. As expected, the RMS values showed similar increases with increasing levels of effort for both types of contractions. Different behaviours for both MPF (contraction*force interaction, ANOVA, P<0.05) and MF (contraction*force interaction, ANOVA, P>0.05) across increasing levels of effort were found between the two types of contraction. The use of step contractions gave rise to a decrease of both MPF and MF with increasing force, while the use of ramp contractions gave rise to an increase in both statistics up to at least 40% MVC followed by a decrease at higher force levels. These findings suggest that the type of contraction used does influence the behaviour of the spectral statistics across increasing force levels and that this could explain the differences obtained in previous studies for the masseter muscle. 相似文献
36.
Sophie Stettler Nuchanard Chiannilkulchai Sylvie Hermann-Le Denmat Dominique Lalo François Lacroute André Sentenac Pierre Thuriaux 《Molecular genetics and genomics : MGG》1993,238(1-2):169-176
The pem locus, which is responsible for the stable maintenance of the low copy number plasmid R100, contains the pemK gene, whose product has been shown to be a growth inhibitor. Here, we attempted to isolate mutants which became tolerant to transient induction of the PemK protein. We obtained 20 mutants (here called pkt for PemK tolerance), of which 9 were temperature sensitive for growth. We analyzed the nine mutants genetically and found that they could be classified into three complementation groups, pktA, pktB and pktC, which corresponded to three genes, ileS, gltX and asnS, encoding isoleucyl-, glutamyl- and asparaginyl-tRNA synthetases, respectively. Since these aminoacyl-tRNA synthetase mutants did not produce the PemK protein upon induction at the restrictive temperature, these mutants could be isolated because they behaved as if they were tolerant to the PemK protein. The procedure is therefore useful for isolating temperature-sensitive mutants of aminoacyl-tRNA synthetases. 相似文献
37.
Evelyne Coppin Sylvie Arnaise Véronique Contamine Marguerite Picard 《Molecular genetics and genomics : MGG》1993,241(3-4):409-414
The mating-type locus of Podospora anserina controls fusion of sexual cells as well as subsequent stages of development of the fruiting bodies. The two alleles at the locus are defined by specific DNA regions comprising 3.8 kb for mat+ and 4.7 kb for mat?, which have identical flanking sequences. Here we present the characterization of several mutants that have lost mat+-specific sequences. One mutant was obtained fortuitously and the other two were constructed by gene replacement. The mutants are deficient in mating with strains of either mat genotype but are still able to differentiate sexual reproductive structures. The loss of the mating type does not lead to any discernible phenotype during vegetative growth: in particular it does not change the life span of the strain. The mutants can recover mating ability if they are transformed with DNA containing the complete mat+ or mat? information. The transformants behave in crosses as do the reference mat+ or mat? strains, thus indicating that the transgenic mat+ and mat? are fully functional even when they have integrated at ectopic sites. 相似文献
38.
PCR-mediated screening and labeling of DNA from clones 总被引:1,自引:0,他引:1
Yun Hai Lu Sylvie Nègre Philippe Leroy Michel Bernard 《Plant Molecular Biology Reporter》1993,11(4):345-349
A simplified and economical protocol for DNA library screening and nonradioactive labeling is described. Bacterial clones
are lysed in 1% of Triton X-100 and subjected to polymerase chain reaction in the presence of digoxigenin-11-dUTP to screen
and simultaneously to label the DNA inserts. Bacteriallysates are stable in storage at −20°C and can be used repeatedly for
PCR-mediated labeling. In this protocol, very low concentrations of dNTP, digoxigenin-dUTP, and primers are used in combination
with a reduced reaction volume. This will considerably reduce the expense of screening and labeling bacterial clones and facilitate
the exchange of DNA probes among laboratories. 相似文献
39.
Freshwater Bacteria Can Methylate Selenium through the Thiopurine Methyltransferase Pathway
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Involvement of the bacterial thiopurine methyltransferase (bTPMT) in natural selenium methylation by freshwater was investigated. A freshwater environment that had no known selenium contamination but exhibited reproducible emission of dimethyl selenide (DMSe) or dimethyl diselenide (DMDSe) when it was supplemented with an organic form of selenium [(methyl)selenocysteine] or an inorganic form of selenium (sodium selenite) was used. The distribution of the bTPMT gene (tpm) in the microflora was studied. Freshwater bacteria growing on 10 μM sodium selenite and 10 μM sodium selenate were isolated, and 4.5 and 10% of the strains, respectively, were shown by colony blot hybridization to hybridize with a Pseudomonas syringae tpm DNA probe. Ribotyping showed that these strains are closely related. The complete rrs sequence of one of the strains, designated Hsa.28, was obtained and analyzed. Its closest phyletic neighbor was found to be the Pseudomonas anguilliseptica rrs sequence. The Hsa.28 strain grown with sodium selenite or (methyl)selenocysteine produced significant amounts of DMSe and DMDSe. The Hsa.28 tpm gene was isolated by genomic DNA library screening and sequencing. BLASTP comparisons of the deduced Hsa.28 bTPMT sequence with P. syringae, Pseudomonas aeruginosa, Vibrio cholerae, rat, and human thiopurine methyltransferase sequences revealed that the levels of similarity were 52 to 71%. PCR-generated Escherichia coli subclones containing the Hsa.28 tpm open reading frame were constructed. E. coli cells harboring the constructs and grown with sodium selenite or (methyl)selenocysteine produced significant levels of DMSe and DMDSe, confirming that the gene plays a role in selenium methylation. The effect of strain Hsa.28 population levels on freshwater DMSe and DMDSe emission was investigated. An increase in the size of the Hsa.28 population was found to enhance significantly the emission of methyl selenides by freshwater samples supplemented with sodium selenite or (methyl)selenocysteine. These data suggest that bTPMT can play a role in natural freshwater selenium methylation processes. 相似文献
40.
J. Custot Jean-Luc Boucher Sandrine Vadon Catherine Guedes Sylvie Dijols Marcel Delaforge Daniel Mansuy 《Journal of biological inorganic chemistry》1996,1(1):73-82
The effects of various compounds bearing an N-OH group such as N-hydroxy-guanidines, amidoximes, and hydroxylamines, on bovine and rat liver arginases was studied. Some of these compounds
with an l-α-amino acid function at an appropriate distance from the N-OH group acted as strong competitive liver arginase inhibitors,
displaying Ki values between 4 and 150 μM. Two compounds, N
ε-hydroxy-l-lysine and N
ω-hydroxy-d,l-indospicine, which exhibited Ki values of 4 and 20 μM (at pH 7.4), were the most potent inhibitors of arginase described
to date. The distance between the α-amino acid and N-OH functions appeared to be crucial for potent inhibition of arginase,
as N
δ-hydroxy-l-ornithine, which has one -CH2 group less than N
ε-hydroxy-l-lysine, exhibited a 37-fold higher Ki value than N
ε-hydroxy-l-lysine. Based on these results, a model for the interaction of N
ω-hydroxyamino-l-α-amino acids with the arginase active site is proposed. This model involves the binding of the N-OH group of the inhibitors
to the arginase Mn(II) center and suggests that N
ε-hydroxy-l-lysine is a good transition state analog of arginase. 相似文献