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41.
Palumbo E Favier CF Deghorain M Cocconcelli PS Grangette C Mercenier A Vaughan EE Hols P 《FEMS microbiology letters》2004,239(1):131-138
A stable mutant of Lactobacillus plantarum deficient in alanine racemase (Alr) was constructed by two successive homologous recombination steps. When the mutant was supplemented with D-alanine, growth and viability were unaffected. Surprisingly, deprivation of d-alanine during exponential growth did not result in a rapid and extensive lysis as observed in Alr-deficient strains of Escherichia coli or Bacillus subtilis. Rather, the starved mutant cells underwent a growth arrest and were gradually affected in viability with a decrease in colony forming units over 99% in less than 24 h. Additionally, fluorescent techniques demonstrated a loss of cell envelope integrity in the starved cells. Prolonged d-alanine starvation resulted in cells with an aberrant morphology. Scanning and transmission electron microscopy analyses revealed an increase in cell length, deficiencies in septum formation, thinning of the cell envelope and perforation of the cell wall in the septum region. We discuss the involvement of peptidoglycan hydrolases in these phenotypic defects in the context of the crucial role played by D-alanine in peptidoglycan biosynthesis and teichoic acids substitution. 相似文献
42.
Marsollier L Sévérin T Aubry J Merritt RW Saint André JP Legras P Manceau AL Chauty A Carbonnelle B Cole ST 《Applied and environmental microbiology》2004,70(10):6296-6298
Accumulative indirect evidence of the epidemiology of Mycobacterium ulcerans infections causing chronic skin ulcers (i.e., Buruli ulcer disease) suggests that the development of this pathogen and its transmission to humans are related predominantly to aquatic environments. We report that snails could transitorily harbor M. ulcerans without offering favorable conditions for its growth and replication. A novel intermediate link in the transmission chain of M. ulcerans becomes likely with predator aquatic insects in addition to phytophage insects. Water bugs, such as Naucoris cimicoides, a potential vector of M. ulcerans, were shown to be infected specifically by this bacterium after feeding on snails experimentally exposed to M. ulcerans. 相似文献
43.
Slowed conduction and thin myelination of peripheral nerves associated with mutant rho Guanine-nucleotide exchange factor 10 下载免费PDF全文
Verhoeven K De Jonghe P Van de Putte T Nelis E Zwijsen A Verpoorten N De Vriendt E Jacobs A Van Gerwen V Francis A Ceuterick C Huylebroeck D Timmerman V 《American journal of human genetics》2003,73(4):926-932
Slowed nerve-conduction velocities (NCVs) are a biological endophenotype in the majority of the hereditary motor and sensory neuropathies (HMSN). Here, we identified a family with autosomal dominant segregation of slowed NCVs without the clinical phenotype of HMSN. Peripheral-nerve biopsy showed predominantly thinly myelinated axons. We identified a locus at 8p23 and a Thr109Ile mutation in ARHGEF10, encoding a guanine-nucleotide exchange factor (GEF) for the Rho family of GTPase proteins (RhoGTPases). Rho GEFs are implicated in neural morphogenesis and connectivity and regulate the activity of small RhoGTPases by catalyzing the exchange of bound GDP by GTP. Expression analysis of ARHGEF10, by use of its mouse orthologue Gef10, showed that it is highly expressed in the peripheral nervous system. Our data support a role for ARHGEF10 in developmental myelination of peripheral nerves. 相似文献
44.
We report a female with Prader-Willi syndrome and hemihypertrophy. We discuss the possibility of an undetected mosaicism for trisomy 15 explaining this unusual feature. 相似文献
45.
Comparison of extenders,dilution ratios and theophylline addition on the function of cryopreserved walleye semen 总被引:2,自引:0,他引:2
Walleye (Stizostedion vitreum) is a species of interest for the diversification of North American aquaculture production, and semen cryopreservation is of particular value to this effort. To test the hypothesis that adjusting semen extender composition and dilution ratio increases sperm quality after thawing, three extenders (Ext1, Ext2, Ext3; all with DMSO as a cryoprotectant) and three dilution ratios (semen/extender: 1:5, 1:9, 1:15) were screened. The best results were obtained when semen was diluted at a 1:15 ratio with Ext 1, Rathbun extender supplemented with 7% DMSO, 4 mg/ml BSA and 7.5 mg/ml ProFam, a soy-based protein (P = 0.05, n = 6). This method resulted in 46 +/- 3% motility of the thawed spermatozoa and a mortality rate of 39 +/- 4% whereas Ext2 and Ext3 resulted in motility rates of only 10 and 5%. respectively. To test an additional hypothesis that phosphodiesterase inhibition improves sperm function, we assessed the fertility of sperm frozen in optimal conditions and thawed in the presence or absence of 5 mM theophylline (n = 5). The best result was achieved in water without theophylline, with fertilization rates ranging from 28.51 +/- 6.84 to 59.02 +/- 1.06% eyed-up stage, and theophylline reduced fertility (P < 0.05). Our data show that Ext1 at a dilution ratio of one part semen to 15 parts extender should be used for walleye semen cryopreservation and that the fertilizing media does not benefit from theophylline supplementation. 相似文献
46.
By monitoring R(pip)/R(Fpg), i.e. the relative sensitivity to hot piperidine and to formamidopyrimidine DNA glycosylase (Fpg protein) of the guanine lesions induced in DNA exposed to UV laser irradiation, we have previously observed that the formation of the two major types of one-electron oxidative guanine modifications, oxazolone and 7,8-dihydro-8-oxoguanine (8-oxodG), depends on DNA conformational features. While oxazolone is largely predominant at each site of single-stranded DNA (R(pip)>R(Fpg)), 8-oxodG is the major lesion at most of the sites of double-stranded DNA (R(pip)R(Fpg) at 20 degrees C and the ratio R(pip)/R(Fpg) does not vary significantly during the melting process. Interestingly, these guanine residues display a high sensitivity to dimethyl sulfoxide methylation while the opposite cytosine residues are unsensitive, suggesting that the prevalence of R(pip) over R(Fpg) is related not to base-pairing disruption but rather to the local helical alteration of the B-DNA stacking geometry. This leads us to propose that the slight variations in the ratios R(pip)/R(Fpg) observed, at individual sites, at temperatures below the helix-coil transition reflect local small-scale breathing motions, unstacking single dinucleotide steps prior to opening. Our results thus support the view that the temperature dependence of the ratio of R(pip)/R(Fpg) at sites of B-DNA provides a sensitive probe of the DNA internal local thermal stability and are discussed in relation with the mechanisms proposed for the intramolecular rearrangement of the guanyl radical. 相似文献
47.
Etienne C Moing A Dirlewanger E Raymond P Monet R Rothan C 《Physiologia plantarum》2002,114(2):259-270
As in many other fleshy fruits, the predominant organic acids in ripe peach ( Prunus persica (L.) Batsch) fruit are malic and citric acids. The accumulation of these metabolites in fruit flesh is regulated during fruit development. Six peach fruit-related genes implicated in organic acid metabolism (mitochondrial citrate synthase; cytosolic NAD-dependent malate dehydrogenase, and cytosolic NADP-dependent isocitrate dehydrogenase) and storage (vacuolar proton translocating pumps: one vacuolar H+ -ATPase, and two vacuolar H+ -pyrophosphatases) were cloned. Five of these peach genes were homologous to genes isolated from fruit in other fleshy fruit species. Phylogenetic and expression analyses suggested the existence of a particular vacuolar pyrophosphatase highly expressed in fruit. The sixth gene was the first cytosolic NAD-dependent malate dehydrogenase gene isolated from fruit. Gene expression was studied during the fruit development of two peach cultivars, a normal-acid (Fantasia) and a low-acid (Jalousia) cultivar. The overall expression patterns of the organic acid-related genes appeared strikingly similar for the two cultivars. The genes involved in organic acid metabolism showed a stronger expression in ripening fruit than during the earlier phases of development, but their expression patterns were not necessarily correlated with the changes in organic acid contents. The tonoplast proton pumps showed a biphasic expression pattern more consistent with the patterns of organic acid accumulation, and the tonoplast pyrophosphatases were more highly expressed in the fruit of the low-acid cultivar during the second rapid growth phase of the fruit. 相似文献
48.
Laurent-Matha V Lucas A Huttler S Sandhoff K Garcia M Rochefort H 《Experimental cell research》2002,277(2):210-219
The cell surface binding, endocytosis, and lysosomal routing of procathepsin D (procath-D) in cancer cells are mostly independent of the mannose-6-phosphate (M6P) receptors. In an attempt to define the receptor involved, we intracellularly cross-linked procath-D with a 68-kDa protein that we identified with specific antibodies as prosaposin in human breast and ovarian cancer cell lines. In cancer cells, this protein-protein interaction was resistant to ammonium chloride or M6P treatment, indicating that it was independent of the M6P receptors. A similar interaction also occurred in the breast cancer cell culture medium between the secreted prosaposin and procath-D. Since these two precursors can be endocytosed, we then determined whether they were interacting with the same cell surface receptor. In fibroblasts, we confirmed that the endocytosis of these two proteins was different since it was generally mediated by the M6P receptors for procath-D and mostly by LRP (LDL receptor-related protein) for prosaposin. In breast cancer cells, prosaposin endocytosis was not detected, in contrast to procath-D endocytosis, suggesting that the majority of procath-D is not internalized as a complex with prosaposin. Moreover, RAP (receptor-associated protein), a ligand inhibiting LRP-mediated endocytosis, prevented internalization of prosaposin in 49-F rat fibroblasts, but did not affect procath-D M6P-independent internalization in MDA-MB231 cells. We conclude that in breast cancer cells, even though procath-D interacts intracellularly and extracellarly with prosaposin, it is endocytosed independent of prosaposin by a receptor different from the M6P receptors and the LRP. 相似文献
49.
A PEX6-defective peroxisomal biogenesis disorder with severe phenotype in an infant, versus mild phenotype resembling Usher syndrome in the affected parents 下载免费PDF全文
Raas-Rothschild A Wanders RJ Mooijer PA Gootjes J Waterham HR Gutman A Suzuki Y Shimozawa N Kondo N Eshel G Espeel M Roels F Korman SH 《American journal of human genetics》2002,70(4):1062-1068
Sensorineural deafness and retinitis pigmentosa (RP) are the hallmarks of Usher syndrome (USH) but are also prominent features in peroxisomal biogenesis defects (PBDs); both are autosomal recessively inherited. The firstborn son of unrelated parents, who both had sensorineural deafness and RP diagnosed as USH, presented with sensorineural deafness, RP, dysmorphism, developmental delay, hepatomegaly, and hypsarrhythmia and died at age 17 mo. The infant was shown to have a PBD, on the basis of elevated plasma levels of very-long- and branched-chain fatty acids (VLCFAs and BCFAs), deficiency of multiple peroxisomal functions in fibroblasts, and complete absence of peroxisomes in fibroblasts and liver. Surprisingly, both parents had elevated plasma levels of VLCFAs and BCFAs. Fibroblast studies confirmed that both parents had a PBD. The parents' milder phenotypes correlated with relatively mild peroxisomal biochemical dysfunction and with catalase immunofluorescence microscopy demonstrating mosaicism and temperature sensitivity in fibroblasts. The infant and both of his parents belonged to complementation group C. PEX6 gene sequencing revealed mutations on both alleles, in the infant and in his parents. This unique family is the first report of a PBD with which the parents are themselves affected individuals rather than asymptomatic carriers. Because of considerable overlap between USH and milder PBD phenotypes, individuals suspected to have USH should be screened for peroxisomal dysfunction. 相似文献
50.
Van Damme EJ Charels D Menu-Bouaouiche L Proost P Barre A Rougé P Peumans WJ 《Planta》2002,214(6):853-862
Thaumatin-like proteins (TLPs) were isolated and characterized from fruits and leaves of elderberry (Sambucus nigra) and their corresponding genes cloned. In addition, the developmental regulation and induction of the different TLPs was followed in some detail. Ripening berries accumulated a fruit-specific TLP during the final stages of maturation. This fruit-specific TLP had no antifungal activity and was devoid of beta-glucanase activity. Leaves constitutively expressed a TLP that closely resembled the fruit-specific homologue. Treatment with jasmonate methyl ester induced two additional TLPs in leaves but did not induce or enhance the expression of TLPs in immature berries. In contrast to jasmonate methyl ester, both ethephon and garlic extract induced the expression of a TLP in unripe berries that normally do not express any TLP. Sequence analysis and molecular modeling indicated that all elderberry thaumatin-like proteins share a high sequence similarity with group-5 pathogenesis-related proteins. However, the proteins encoded by the different sequences differed from each other in isoelectric point and the distribution of the charges on the surface of the molecule. 相似文献