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Mutation Leading (mutation + leading)
Selected AbstractsAuxotrophic mutant of the cyanobacterium Nostoc muscorum showing absolute requirement of Cs+ or Rb+ for diazotrophy and autotrophyJOURNAL OF BASIC MICROBIOLOGY, Issue 4 2006Santosh Bhargava Dr. Caesium-resistant (Cs+ -R) mutant clones of the cyanobacterium Nostoc muscorum were characterized for diazotrophic growth in a medium devoid of Cs+ or Rb+ or both. Cs+ -R phenotype suffered severe genetic damage of a pleiotropic nature affecting diazotrophic growth, chlorophyll a content, nitrogenase activity and photosynthetic O2 evolution. Mutation leading to development of Cs+ -R phenotype could be overcome by availability of Cs+/Rb+. Parent and mutant strains were similar with respect to their Cs+/Rb+ uptake. Available data suggests operation of an efficient coupling of the two incompatible reactions viz. oxygenic photosynthesis and oxygen sensitive N2 fixation in this cyanobacterium. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Novel inactivating mutations of FANCC in Brazilian patients with Fanconi anemia,,HUMAN MUTATION, Issue 2 2006Jane Yates Abstract We have identified three novel FANCC mutations, a truncating single base insertion in exon 4 (c.455_456dupA), a point mutation in exon 13 (c.1390C>T), and a splice site mutation leading to deletion of exon 9, in two Brazilian FA-C patients, each a compound heterozygote. Using complementation analyses, we confirmed that two of these mutations inactivate the function of the FANCC protein. Published 2006 Wiley-Liss, Inc. [source] The Causal Element for the Lactase Persistence/ non-persistence Polymorphism is Located in a 1 Mb Region of Linkage Disequilibrium in EuropeansANNALS OF HUMAN GENETICS, Issue 4 2003M. Poulter Summary Expression of lactase in the intestine persists into adult life in some people and not others, and this is due to a cis -acting regulatory polymorphism. Previous data indicated that a mutation leading to lactase persistence had occurred on the background of a 60 kb 11-site LCT haplotype known as A (Hollox et al. 2001). Recent studies reported a 100% correlation of lactase persistence with the presence of the T allele at a CT SNP at ,14 kb from LCT, in individuals of Finnish origin, suggesting that this SNP may be causal of the lactase persistence polymorphism, and also reported a very tight association with a second SNP (GA ,22 kb) (Enattah et al. 2002). Here we report the existence of a one megabase stretch of linkage disequilibrium in the region of LCT and show that the ,14 kb T allele and the ,22 kb A allele both occur on the background of a very extended A haplotype. In a series of Finnish individuals we found a strong correlation (40/41 people) with lactose digestion and the presence of the T allele. The T allele was present in all 36 lactase persistent individuals from the UK (phenotyped by enzyme assay) studied, 31/36 of whom were of Northern European ancestry, but not in 11 non-persistent individuals who were mainly of non-UK ancestry. However, the CT heterozygotes did not show intermediate lactase enzyme activity, unlike those previously phenotyped by determining allelic transcript expression. Furthermore the one lactase persistent homozygote identified by having equally high expression of A and B haplotype transcripts, was heterozygous for CT at the ,14 kb site. SNP analysis across the 1 megabase region in this person showed no evidence of recombination on either chromosome between the ,14 kb SNP and LCT. The combined data shows that although the ,14 kb CT SNP is an excellent candidate for the cause of the lactase persistence polymorphism, linkage disequilibrium extends far beyond the region searched so far. In addition, the CT SNP does not, on its own, explain all the variation in expression of LCT, suggesting the possibility of genetic heterogeneity. [source] Prevalence of SAP gene defects in male patients diagnosed with common variable immunodeficiencyCLINICAL & EXPERIMENTAL IMMUNOLOGY, Issue 3 2004D. EASTWOOD SUMMARY The molecular basis of common variable immunodeficiency (CVID) is undefined, and diagnosis requires exclusion of other diseases including X-linked lymphoproliferative disease (XLP). This rare disorder of immunedysregulation presents typically after Epstein,Barr virus infection and results from defects in the SAP (SLAM associated protein) gene. SAP mutations have been found in a few patients diagnosed previously as CVID, suggesting that XLP may mimic CVID, but no large-scale analysis of CVID patients has been undertaken. We therefore analysed 60 male CVID and hypogammaglobulinaemic patients for abnormalities in SAP protein expression and for mutations in the SAP gene. In this study only one individual, who was found later to have an X-linked family history, was found to have a genomic mutation leading to abnormal SAP cDNA and protein expression. These results demonstrate that SAP defects are rarely observed in CVID patients. We suggest that routine screening of SAP may only be necessary in patients with other suggestive clinical features. [source] | ||||||||||