Search results for "Mutant"
showing 10 items of 670 documents
C172S Substitution in the Chloroplast-encoded Large Subunit Affects Stability and Stress-induced Turnover of Ribulose-1,5-bisphosphate Carboxylase/Ox…
1999
Previous work has indicated that the turnover of chloroplast ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco; EC 4.1.1. 39) may be controlled by the redox state of certain cysteine residues. To test this hypothesis, directed mutagenesis and chloroplast transformation were employed to create a C172S substitution in the Rubisco large subunit of the green alga Chlamydomonas reinhardtii. The C172S mutant strain was not substantially different from the wild type with respect to growth rate, and the purified mutant enzyme had a normal circular dichroism spectrum. However, the mutant enzyme was inactivated faster than the wild-type enzyme at 40 and 50 degrees C. In contrast, C172S mutant …
The impact of growth history and flagellation on the adhesion of variousListeria monocytogenesstrains to polystyrene
2009
International audience; The contribution of growth history and flagella to adhesion of Listeria monocytogenes was analysed. An in-frame deletion on the flagellin encoding gene (flaA) was performed in L. monocytogenes EGD-e to compare its adhesion ability with the parental strain, after cultivation at various pH values and temperatures. The pH, as well as the temperature, affected the adhesion of L. monocytogenes EGD-e. In addition, the adhesion of L. monocytogenes EGD-e was reduced in energy-depressed cells. Conversely, the physicochemical bacterial surface characteristics affected by growth history did not influence the adhesion. Adhesion variations observed among environmental and clinica…
Effects of pharmacological agents on the lifespan phenotype of Drosophila DJ-1beta mutants.
2010
Mutations in the DJ-1 gene cause autosomal recessive, early-onset Parkinsonism. The DJ-1 protein exerts a protective role against oxidative stress damage, working as a cellular oxidative stress sensor, and it seems to regulate gene expression at different levels. In Drosophila, two DJ-1 orthologs have been identified: DJ-1β and DJ-1β. Several studies have shown that loss of DJ-1β function causes Parkinson's disease (PD)-like phenotypes in flies such as age-dependent locomotor defects, reduced lifespan, and enhanced sensitivity to toxins that induce oxidative stress, like the herbicide paraquat. However, no dopaminergic neurodegeneration is observed. These results suggested that both locomot…
Instability of plasmid-encoded citrate permease in Leuconostoc
1996
M. KIHAL, H. PREVOST, M.E. LHOTTE, D.Q. HUANG AND C. DIVIES. 1996. The conversion from citrate positive (Cit+) to citrate negative (Cit-) phenotype of six strains of Leuconostoc mesetiteroides was followed during growth in milk and buffered or unbuffered MRS medium at 30 or 37°C. High rate of loss of Cit+ phenotype was observed. The Cit- phenotype was found to be linked to the loss of 22 to 23 kb plasmids. All Cit- mutants isolated from Leuc. mesenteroides subsp. cremoris 195 reverted spontaneously to the Cit+ phenotype. Hybridization experiments using a 0.8 kb fragment of the citP gene of Leuc. mesenteroides showed that all the plasmids which were lost in Cit- mutants encoded for a citrate…
Mast cell-derived mediators promote murine neutrophil effector functions
2013
Mast cells are able to trigger life-saving immune responses in murine models for acute inflammation. In such settings, several lines of evidence indicate that the rapid and protective recruitment of neutrophils initiated by the release of mast cell-derived pro-inflammatory mediators is a key element of innate immunity. Herein, we investigate the impact of mast cells on critical parameters of neutrophil effector function. In the presence of activated murine bone marrow-derived mast cells, neutrophils freshly isolated from bone marrow rapidly lose expression of CD62L and up-regulate CD11b, the latter being partly driven by mast cell-derived TNF and GM-CSF. Mast cells also strongly enhance neu…
PKSP-dependent reduction of phagolysosome fusion and intracellular kill of Aspergillus fumigatus conidia by human monocyte-derived macrophages.
2002
Summary Previously, we described the isolation of an Aspergillus fumigatus mutant producing non-pigmented conidia, as a result of a defective polyketide synthase gene, pksP (polyketide synthase involved in pigment biosynthesis). The virulence of the pksP mutant was attenuated in a murine animal infection model and its conidia showed enhanced susceptibility towards damage by monocytes in vitro. Because macrophage-mediated killing is critical for host resistance to aspergillosis, the interaction of both grey-green wild-type conidia and white pksP mutant conidia with human monocyte-derived macrophages (MDM) was studied with respect to intracellular processing of ingested conidia. After phagocy…
460. MGMTP140K Vector Constructs for Efficient In Vivo Enrichment of Genetically Corrected Cells Following Hematopoietic Cell Gene Transfer
2006
MGMTP140K, a mutant of the DNA repair protein O6-methylguanine-DNA methyltransferase (MGMT) resistant to the inhibitor O6-benzylguanine (BG), protects hematopoietic stem cells (HSC) from the toxicity of alkylating agents such as temozolomide (TMZ) and, therefore, allows efficient in vivo enrichment of transduced cells by BG/TMZ therapy. MGMTP140K has been proposed as a selection marker in gene therapy of monogeneic diseases. If used for this purpose, however, MGMTP140K expression in vectors containing internal ribosomal entry sites (IRES) would be from the compromised 3' position, as the 5' position will be required for the therapeutic gene. Thus, we have investigated SFFV/MESV-based vector…
Penicillium auxotrophic mutants can be detected by suing xanthene dyes
1987
Auxotrophic mutants ofPenicillium spp. have been directly isolated after mutagenic treatment from agar plates containing Xanthene dyes. They grow as characteristic small colored colonies. Some strains were tested and they showed a differential response depending on the Xanthene dye used.
Gene amplification in fibroblasts from ataxia telangiectasia (AT) patients and in X-ray hypersensitive AT-like Chinese hamster mutants.
2001
In search of functions involved in the regulation of gene amplification, and given the relevance of chromosome breakage in initiating the process, we analyzed the gene amplification ability of cells hypersensitive to inducers of DNA double-strand breaks and defective in cell cycle control: two human fibroblast strains derived from patients affected by ataxia telangiectasia (AT) and two hamster mutant cell lines belonging to complementation group XRCC8 of the rodent X-ray-sensitive mutants. These mutants are considered hamster models of AT cells. To measure gene amplification, the frequency and the rate of occurrence of N-(phosphonacetyl)-L-aspartate resistant cells were determined. In both …
Single amino acids in the lumenal loop domain influence the stability of the major light-harvesting chlorophyll a/b complex.
2004
The major light-harvesting complex of photosystem II (LHCIIb) is one of the most abundant integral membrane proteins. It greatly enhances the efficiency of photosynthesis in green plants by binding a large number of accessory pigments that absorb light energy and conduct it toward the photosynthetic reaction centers. Most of these pigments are associated with the three transmembrane and one amphiphilic alpha helices of the protein. Less is known about the significance of the loop domains connecting the alpha helices for pigment binding. Therefore, we randomly exchanged single amino acids in the lumenal loop domain of the bacterially expressed apoprotein Lhcb1 and then reconstituted the muta…