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Homozygous Individuals (homozygous + individual)
Selected AbstractsOsRecQ1, a QDE-3 homologue in rice, is required for RNA silencing induced by particle bombardment for inverted repeat DNA, but not for double-stranded RNATHE PLANT JOURNAL, Issue 2 2008Hui Chen Summary Based on the nucleotide sequence of QDE-3 in Neurospora crassa, which is involved in RNA silencing, rice (Oryza sativa) mutant lines disrupted by the insertion of the rice retrotransposonTos17 were selected. Homozygous individuals from the M1 and M2 generations were screened and used for further analyses. The expression of the gene was not detected in leaves or calli of the mutant lines, in contrast to the wild type (WT). Induction of RNA silencing by particle bombardment was performed to investigate any effects of the OsRecQ1 gene on RNA silencing with silencing inducers of the GFP (green fluorescence protein)/GUS (, -glucuronidase) gene in the mutant lines. The results showed that OsRecQ1 is required for RNA silencing induced by particle bombardment for inverted-repeat DNA, but not for double-stranded RNA (dsRNA). The levels of transcripts from inverted-repeat DNA were much lower in the mutant lines than those in the WT. Furthermore, no effects were observed in the accumulation of endogenous microRNAs (miR171 and miR156) and the production of the short interspersed nuclear element retroelement by small interfering RNA. On the basis of these results, we propose that OsRecQ1 may participate in the process that allows inverted repeat DNA to be transcribed into dsRNA, which can trigger RNA silencing. [source] Identification of a novel single nucleotide polymorphism in the first tandem repeat sequence of the thymidylate synthase 2R alleleINTERNATIONAL JOURNAL OF CANCER, Issue 9 2007Lisa F. Lincz Abstract Thymidylate synthase (TS) activity is an important determinant of response to chemotherapy with fluoropyrimidine prodrugs and its expression is largely determined by the number of functional upstream stimulatory factor (USF) E-box consensus elements present in the 5,regulatory region of the TYMS gene. Two known polymorphisms in this area, a variable number of tandem repeat (VNTR) consisting of 2 or 3 repeats (2R/3R) of a 28-bp sequence and a further G > C single nucleotide substitution within the second repeat of the 3R, result in genotypes with between 2 and 4 functional repeats in most humans. Here, we identify a further G > C SNP in the first repeat of the TYMS 2R allele, which effectively abolishes the only functional USF protein binding site in this promoter. The frequency of the new allele was found to be 4.2% (95% CI = 1.4,9.6%), accounting for 8.8% (95% CI = 2.9,19.3%) of all 2R alleles in our patient cohort. Thus, we observed that the lowest number of inherited functional binding sites is 1 instead of 2 as previously thought, and could potentially be 0 in a homozygous individual. This would severely decrease TS expression and may have implications for predicting efficacy and toxicity of therapy with commonly used fluorouracil-based therapy regimes. © 2007 Wiley-Liss, Inc. [source] Is natural selection a plausible explanation for the distribution of Idh- 1 alleles in the cricket Allonemobius socius?ECOLOGICAL ENTOMOLOGY, Issue 1 2006Diana L. Huestis Abstract., 1.,Allozyme alleles in natural populations have been proposed as either neutral markers of genetic diversity or the product of natural selection on enzyme function, as amino acid substitutions that change electrophoretic mobility may also alter enzyme performance. To address these possibilities, researchers have used both correlative analyses and empirical studies. 2.,Here, geographically structured variation of the enzyme isocitrate dehydrogenase (Idh- 1) in the striped ground cricket Allonemobius socius Scudder (Orthoptera: Gryllidae) is examined. The distributions of Idh- 1 alleles appear to be related to environmental gradients, as allele frequencies showed significant relationships with mean annual temperature and precipitation. Specifically, the slowest mobility allele was more frequent at colder temperatures, while the converse occurred for the fastest mobility allele. 3.,An exploratory experiment was performed to examine fitness effects of possessing different Idh- 1 alleles at two temperatures to test the hypothesis that the geographic structure of this locus may reflect environmental adaptation. Results showed that a significant interaction between temperature and Idh- 1 genotype affected the number of eggs laid, with success of homozygous individuals matching environmental expectations. 4.,The above results show that (1) variation in the frequency of Idh- 1 alleles is significantly related to environmental gradients in the eastern U.S.A. and (2) alternative alleles of Idh- 1 appear to influence the egg-laying ability of individuals differently depending on environmental temperature. Together, these results suggest that natural selection is a plausible mechanism underlying the distribution of Idh- 1 alleles in this species, although more detailed studies are needed. [source] A variable number of tandem repeats polymorphism influences the transcriptional activity of the neonatal Fc receptor ,-chain promoterIMMUNOLOGY, Issue 1 2006Ulrich J. H. Sachs Summary The neonatal Fc receptor, FcRn, plays a central role in immunoglobulin G (IgG) transport across placental barriers. Genetic variations of FcRn-dependent transport across the placenta may influence antibody-mediated pathologies of the fetus and the newborn. Sequencing analysis of 20 unrelated individuals demonstrated no missense mutation within the five exons of the FcRn gene. However, a variable number of tandem repeats (VNTR) region within the FcRn promoter was observed, consisting of five different alleles (VNTR1,VNTR5). Alleles with two (VNTR2) and three (VNTR3) repeats were found to be most common in Caucasians (7·5 and 92·0%, respectively). Real-time polymerase chain reaction revealed that monocytes from VNTR3 homozygous individuals express 1·66-fold more FcRn transcript than do monocytes from VNTR2/VNTR3 heterozygous individuals (P = 0·002). In reporter plasmid assays, the VNTR3 allele supported the transcription of a reporter gene twice as effectively as did the VNTR2 allele (P = 0·003). Finally, under acidic conditions, monocytes from VNTR3 homozygous individuals showed an increased binding to polyvalent human IgG when compared with monocytes from VNTR2/VNTR3 heterozygous individuals (P = 0·021). These data indicate that a VNTR promoter polymorphism influences the expression of the FcRn receptor, leading to different IgG-binding capacities. [source] G1793A polymorphisms in the methyl- enetetrahydrofolate gene: Effect of folic acid on homocysteine levelsMOLECULAR NUTRITION & FOOD RESEARCH (FORMERLY NAHRUNG/FOOD), Issue 8 2006Sandra Soares Melo Abstract Mutations or polymorphisms in the gene of the enzyme methylenetetrahydrofolate (MTHFR) are associated with hyperhomocysteinemia and possibly with an elevated risk for vascular diseases. A study was conducted on 83 individuals with type 2 diabetes in order to determine the allelic and genotypic frequencies of the G1793A mutation and to assess the effect of folic acid supplementation on plasma homocysteine concentrations. The patients were attended by the Diabetes and Hypertension Program , Balneario Camboriu/SC and received daily supplements containing 1 mg of folic acid for 3 months. DNA was previously extracted from leukocytes and the G1793A mutation was detected by PCR-RFLP. Blood samples were collected during the basal period and after supplementation for the determination of homocysteine by HPLC, and of folic acid and vitamin B12 by RIA. The allele frequency for the G1793A mutation was 3.01% and no homozygous individuals with mutant alleles were detected. Hyperhomocysteinemia was diagnosed in 27.71% of the patients, folic acid deficiency in 15.66%, and vitamin B12 deficiency in 7.23%. Plasma homocysteine concentrations were inversely correlated with folic acid (r = ,0.27, p = 0.01) and vitamin B12 (r = ,0.21; p = 0.05) concentrations. The individuals with a heterozygous genotype for the G1793A mutation showed borderlines or deficient values in folic acid and vitamin B12 concentrations compared to individuals with a normal genotype. Hyperhomocysteinemia and the vitamin deficiencies presented by type 2 diabetic individuals, included with a heterozygous genotype for the G1793A mutation in the MTHFR gene, reached normal values by daily folic acid supplementation. [source] Rheumatoid arthritis association with the FCRL3 ,169C polymorphism is restricted to PTPN22 1858T,homozygous individuals in a Canadian populationARTHRITIS & RHEUMATISM, Issue 12 2006William G. Newman Objective Variants in genes encoding the Fc receptor,like 3 (FcRL-3) and the class II major histocompatibility complex (MHC) transactivator proteins have been associated with an increased risk of rheumatoid arthritis (RA) in Japanese and Nordic populations, respectively. The aim of this study was to investigate these associations in a Canadian Caucasian cohort of RA cases and healthy controls. Methods A total of 1,187 RA patients and 462 healthy controls were genotyped for FCRL3 and MHC2TA gene variants associated with RA. Epistasis between the FCRL3 ,169C and the PTPN22 1858T variants was also examined. Results An association was detected between RA and both the FCRL3 ,169C allele (OR 1.19, P = 0.023) and the homozygous genotype (OR 1.41, P = 0.027), but association of the MHC2TA promoter region variant (,168G) with RA was not replicated. Stratification of the RA cohort by PTPN22 genotypes revealed the FCRL3 risk variant and RA association was stronger in the patient subgroup lacking PTPN22 1858T variants (P = 0.004) and was not detectable in the subgroup with PTPN22 1858T variants (P = 0.52). The PTPN22 association with RA was greater in the absence than in the presence of the FCRL3 ,169C allele (P = 0.0008 versus P = 0.001). The PTPN22 1858T variant also increased the risk of autoimmune thyroid disease (AITD) in the RA patients, whereas the FCRL3 risk variant was protective against AITD. Conclusion Our findings support an association of RA with an FCRL3 functional polymorphism and reveal that this association is stronger in the absence of PTPN22 risk genotypes. These findings support a genetic heterogeneity across RA populations, suggesting that both the FCRL3 and PTPN22 genes play roles in RA susceptibility, but in different individuals. [source] | |||||||||||||