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31.
The chromosomal distribution of P and I transposable elements was studied, by in situ hybridisation, in 25 isofemale lines of Drosophila melanogaster collected at Nasr'Allah in Tunisia. An important interline variability for the number of copies of both elements was revealed. The mean number of copies per line was 31.3 for P and 21.0 for I. Certain chromosome arms had a higher frequency of copies than others: arm 3R had the highest frequency of I elements; the X chromosome had the highest frequency of P elements and the lowest frequency of I elements. For both P and I elements the number of copies on the different chromosome arms is independent. Furthermore, there is no significant correlation between the number of copies of P and the number of copies of I for a given line. A study of the localisation of hybridisation sites on the X chromosome revealed the existence of preferred regions for each family. The population studied was of type M' in the P-M system of hybrid dysgenesis. There is no direct relationship between the M potential of an isofemale line and its number of copies of P elements. These results are compared with those of other investigators and the consequences for cytotype determination are discussed. 相似文献
32.
Catherine Ferrand Dominique Clarous Christine Delteil Michel J. Weber 《Journal of neurochemistry》1986,46(2):349-358
The secretion and cellular localization of the molecular forms of acetylcholinesterase (AChE) were studied in primary cultures of rat sympathetic neurons. When cultured under conditions favoring a noradrenergic phenotype, these neurons synthesized and secreted large quantities of the tetrameric G4, and the dodecameric A12 forms, and minor amounts of the G1 and G2 forms. When these neurons adopted the cholinergic phenotype, i.e., in the presence of muscle-conditioned medium, the development of the cellular A12 form was completely inhibited. These neurons secreted only globular, mainly G4, AChE. Both cellular and secreted A12 AChE in adrenergic cultures aggregated at an ionic strength similar to that of the culture medium, raising the hypothesis that this form was associated with a polyanionic component of basal lamina. In noradrenergic neurons, 60-80% of the catalytic sites were exposed at the cell surface. In particular, 80% of G4 form, but only 60% of the A12 form, was external, demonstrating for the A12 form a sizeable intracellular pool. The hydrophobic character of the molecular forms was studied in relation to their cellular localization. As in muscle cells, most of the G4 form was membrane-bound. Whereas 76% of the cell surface A12 form was solubilized in the aqueous phase by high salt concentrations, only 50% of the intracellular A12 form was solubilized under these conditions. The rest of intracellular A12 could be solubilized by detergents and was thus either membrane-bound or entrapped in vesicles originating from, e.g., the Golgi apparatus. 相似文献
33.
Lionel Sibold Dominique Pariot Lakshmi Bhatnagar Marc Henriquet Jean-Paul Aubert 《Molecular & general genetics : MGG》1985,200(1):40-46
Summary Using the Southern hybridization technique, homologies were examined between restricted DNA of four methanogenic bacteria (Methanobacterium ivanovi, Methanobacterium thermoautotrophicum, Methanococcus voltae, Methanosarcina barkeri) and the nif (nitrogen fixation) genes of Klebsiella pneumoniae and Anabaena strain 7120. With K. pneumoniae probes, no hybridization was observed with nifA, nifNE, and nifJ but positive results were obtained with the nifHDK genes coding for nitrogenase. Homology was detected, in the four strains, with K. pneumoniae and Anabaena nifH probes. In M. voltae and M. ivanovi, the homology found with nifH was estimated to be about 70% and a weaker hybridization was observed also with nifD and nifK. In M. voltae, the sequence homologous to nifH was found on a 3.0 kbp HindIII fragment and sequences homologous to nifD and nifK on a 3.8 kbp HindIII fragment. The 3.0 kbp fragment was cloned and the region homologous to nifH was localized more precisely. When this fragment was used as a probe against other DNAs, it behaved as a K. pneumoniae and Anabaena nifH probe. The results suggest that the structural genes for nitrogenase may be present in archaebacteria and raise interesting questions regarding their evolution. 相似文献
34.
Dominique Thuault Friedhelm Meinhardt Karl Esser 《Applied microbiology and biotechnology》1985,21(3-4):196-199
Summary Mitochondrial (mt) DNA of the white rot fungus Polyporus ciliatus was isolated and characterized. As a result of detailed restriction enzyme analysis, a physical map was established showing that this circular DNA has a molecular weight of 88.2 kb. By heterologous cross hybridization the sites of three mt genes were recognized. By nonselective cloning of mt DNA fragments in Saccharomyces cerevisiae, an autonomously replicating sequence (ars) was identified which has potential application in the development of a prokaryotic/eukaryotic shuttle vector. 相似文献
35.
Teresa de Sa E Melo Patrice Morlière Sonia Goldstein René Santus Louis Dubertret Dominique Lagrange 《Biochemical and biophysical research communications》1984,120(2):670-676
5-methoxypsoralen (5-MOP) binds to human serum low density lipoproteins (LDL) according to a two-step process. Scatchard analysis of the first step yields K = 1.4 × 105 M?1 and 4 binding sites. It involves the LDL apoprotein. The second step corresponds to a solubilization, in the lipidic core, of ? 45 molecules of 5MOP per LDL molecule. It is accompanied by a large blue shift of the 5MOP fluorescence. The ability of LDL to bind 5MOP and to carry it into various cells may explain some biological effects sometimes encountered during PUVA therapy. 相似文献
36.
Annie Conter Dominique Dupouy Christine Delteil Hubert Planel 《Archives of microbiology》1986,144(3):286-290
Previous results from this laboratory have shown that very low chronic doses of gamma radiation can stimulate proliferation of the Cyanobacterium Synechococcus lividus. This modification of cell proliferation occurred during the first doubling. In this paper, we have compared the metabolism of cells cultivated in a normal environment or under chronic irradiation. Incubation of the cells in a new medium induced a high superoxide dismutase (EC 1.15.1.1, SOD) activity at the 18th hour and a degradation of phycocyanin, thus demonstrating that cells were submitted to a photooxidative stress. This increase in superoxide dismutase activity was followed by concomittant peaks of glutathione reductase (EC 1.6.4.2, GR) and glucose-6-phosphate dehydrogenase (EC 1.1.1.49, G6P-DH) at the 24th hour. Irradiated cultures at a dose of 53.5 mGray/year show an earlier and higher peak of SOD, GR, and G6P-DH. In a second stage, cultures showed an earlier onset of photosynthesis under irradiation, as evidenced by an increase in pigment content and an enhancement of glyceraldehyde-3-phosphate dehydrogenase (EC 1.2.1.13, GAP-DH). These results show that the radiostimulation is related to the activation of enzymes protecting against peroxides that were induced under oxidative circumstances and to the activation of a glucose catabolism via the oxidative pentose phosphate pathway.Abbreviations mGy
milli-Gray
- SOD
superoxide dismutase
- G6P-DH
glucose-6-phosphate dehydrogenase
- GAP-DH
glycer-aldehyde-3-phosphate dehydrogenase
- GSSG
oxidized glutathione 相似文献
37.
The proα2 (V) collagen gene (COL5A2) maps to 2q14→2q32, syntenic to the proα1 (III) collagen locus (COL3A1) 总被引:3,自引:0,他引:3
Cécile Huerre-Jeanpierre Isabelle Henry M. Bernard Pia Gallano Dominique Weil K. H. Grzeschik F. Ramirez Claudine Junien 《Human genetics》1986,73(1):64-67
Summary A recombinant probe specific for the pro2 chain of human Type V collagen has been used for the localization of the corresponding gene (COL5A2) to chromosome 2. Regional mapping by in situ hybridization and analysis of DNA from humanxrodent cell lines indicated that COL5A2 is confined within the segment 2q142q32, thus syntenic to the pro1 (III) collagen gene (COL3A1). 相似文献
38.
Dominique Duviard 《Insectes Sociaux》1969,16(2):115-133
Résumé La ComposéeVernonia guineensis Benth., abondante dans les savanes préforestières de Côte d'Ivoire, fleurit quelques semaines après le passage des feux de brousse. Plusieurs espèces de Fourmis sont récoltées régulièrement sur la plante: ce sont surtoutCamponotus acvapimensis et unCremastogaster du genreAcroclia.Les Fourmis se nourrissent de sécrétions sucrées qui suintent au niveau des bractées des jeunes capitules, mais pratiquent également l'élevage d'Homoptères.Divers types de constructions sont décrits et, en particulier, les loges édifiées parC. acvapimensis pour abriter un Jassidæ:Selenocephalus sp.L'influence de l'environnement végétal sur la faune myrmécologique exploitantV. guineensis est mise en évidence.
Summary Vernonia guineensis Benth. (Compositæ). common in the forest-savanna mosaic of Ivory Coast, blooms a few weeks after the fires. Several species of Ants are collected then on the forb; especiallyCamponotus acvapimensis and a species ofCremastogaster (Acroclia).These ants feed on seepings from the young flower heads, and search for exsudates of Homopterans.Various buildings are described, particularly shelters made byC. acvapimensis for the leaf—hopperSelenocephalus sp.Influence of botanical environment on the ants exploitingV. guineensis is shown.相似文献
39.
Dominique Le Grand Michel Solsona Renate Rosengarten francois Poumarat 《FEMS microbiology letters》1996,144(2-3):267-275
Abstract The variability of predominant Mycoplasma bovis surface antigens in the presence of specific immune pressure was analyzed in an in vitro assay to determine if M. bovis could escape immune destruction. We have shown that serum antibodies from immunized or experimentally infected calves and monoclonal antibodies which specifically react with previously characterized or as yet undefined major M. bovis membrane surface proteins cause repression of expression or shortening of the target protein, or induce switching to expression of an antigenically distinct variant protein. We have further demonstrated that removal of the inducing antibody results in reversion to the original phenotype. These results suggest that the level of expression and the length of M. bovis surface antigens in the host is modulated by cognate antibodies. According to the surface antigenic variation systems, random selection of preexisting variants resistant to antibody-mediated inhibition or direct regulation of gene expression may be means by which this organism evades host immune defences. 相似文献
40.
Dominique Rumeau Stephan Cuiné Laurent Fina Nathalie Gault Michel Nicole Gilles Peltier 《Planta》1996,199(1):79-88
The intracellular compartmentation of carbonic anhydrase (CA; EC 4.2.1.1), an enzyme that catalyses the reversible hydration of CO2 to bicarbonate, has been investigated in potato (Solanum tuberosum L.) leaves. Although enzyme activity was mainly located in chloroplasts (87% of total cellular activity), significant activity (13%) was also found in the cytosol. The corresponding CA isoforms were purified either from chloroplasts or crude leaf extracts, respectively. The cytosolic isoenzyme has a molecular mass of 255 000 and is composed of eight identical subunits with an estimated M
r of 30000. The chloroplastic isoenzyme (M
r 220000) is also an octamer composed of two different subunits with M
r estimated at 27 000 and 27 500, respectively. The N-terminal amino acid sequences of both chloroplastic CA subunits demonstrated that they were identical except that the M
r-27 000 subunit was three amino acids shorter than that of the M
r-27 500 subunit. Cytosolic and chloroplastic CA isoenzymes were found to be similarly inhibited by monovalent anions (Cl–, I–, N
3
-
and NO
3
-
) and by sulfonamides (ethoxyzolamide and acetozolamide). Both CA isoforms were found to be dependent on a reducing agent such as cysteine or dithiothreitol in order to retain the catalytic activity, but 2-mercaptoethanol was found to be a potent inhibitor. A polyclonal antibody directed against a synthetic peptide corresponding to the N-terminal amino acid sequence of the chloroplastic CA monomers also recognized the cytosolic CA isoform. This antibody was used for immunocytolocalization experiments which confirmed the intracellular compartmentation of CA: within chloroplasts, CA is restricted to the stroma and appears randomly distributed in the cytosol.Abbreviations BSA
bovine serum albumin
- CA
carbonic anhydrase
- PMSF
phenylmethylsulphonyl fluoride
- BAM
benzamidine
- DTT
dithiothreitol
- 2-ME
2-mercaptoethanol
- PVDF
polyvinylidene difluoride
The authors thanks P. Carrier and Dr. B. Dimon for technical assistance with the mass-spectrometry measurements. 相似文献