Home About us Contact
|
Home About us Contact | ||
|
|
||
One Polymorphism (one + polymorphism)
Selected AbstractsOpposite shell-coiling morphs of the tropical land snail Amphidromus martensi show no spatial-scale effectsECOGRAPHY, Issue 4 2006Paul G. Craze Much can be learned about evolution from the identification of those factors maintaining polymorphisms in natural populations. One polymorphism that is only partially understood occurs in land snail species where individuals may coil clockwise or anti-clockwise. Theory shows that polymorphism in coiling direction should not persist yet species in several unrelated groups of land snails occur in stably polymorphic populations. A solution to this paradox may advance our understanding of evolution in general. Here, we examine two possible explanations: firstly, negative frequency-dependent selection due to predation; secondly, random fixation of alternative coiling morphs in tree-sized demes, giving the impression of wider polymorphism. We test these hypotheses by investigating morph-clustering of empty shells at two spatial scales in Amphidromus martensi populations in northern Borneo: the spatial structure of snail populations is relatively easy to estimate and this information may support one or other of the hypotheses under test. For the smaller scale we make novel use of a statistic previously used in botanical studies (the K-function statistic), which allows clustering of more than one morph to be simultaneously investigated at a range of scales and which we have corrected for anisotropy. We believe this method could be of more general use to ecologists. The results show that consistent clustering or separation of morphs cannot be clearly detected at any spatial scale and that predation is not frequency-dependent. Alternative explanations that do not require strong spatial structuring of the population may be needed, for instance ones involving a mechanism of selection actively maintaining the polymorphism. [source] Expression patterns and association analysis of the porcine DHX58 geneANIMAL GENETICS, Issue 5 2010X. Y. Li Summary RIG-1 signalling is responsible for the detection of cytoplasmic viral RNA molecules. DEXH (Asp-Glu-X-His) box polypeptide 58 (encoded by DHX58) is a negative regulator of the RIG-1 signalling pathway. In human, the DHX58 gene can be upregulated and can inhibit the RIG-1 signalling pathway during viral infection. In this study, porcine DHX58 gene expression patterns were studied. According to our results, the porcine DHX58 gene was upregulated not only by the stimulation of Poly I:C but also by the stimulation of 1ipopolysaccharides (LPS). One polymorphism (g.4919G>C), detected in the ninth intron, was significantly associated with some blood parameters including the red cell distribution width of 1-day-old pigs and white blood cell counts, lymphocyte absolute counts, and platelet distribution width of 17-day-old pigs (P < 0.05). Moreover, the individuals with the genotype GG have a significantly higher mean white blood cell count than individuals with genotype CC or GC (P < 0.05). Our study indicates that DHX58 is an important gene that is associated with the immune response in swine. [source] H intragenic polymorphisms and haplotype analysis in the ornithine transcarbamylase (OTC) gene and their relevance for tracking the inheritance of OTC deficiency,,HUMAN MUTATION, Issue 5 2002Consuelo Climent Abstract The "private" nature of most mutations causing ornithine transcarbamylase (OTC) deficiency makes mutation identification in the patients difficult. Further, the PCR-amplification technology generally used for the genetic diagnosis of the deficiency misses large deletions in carrier females. Intragenic OTC polymorphisms may allow detection of these deletions and may represent an alternative to mutation detection for prenatal diagnosis and carrier identification in families with a history of inherited OTC deficiency. A new highly informative polymorphism (allele frequencies, 0.66/0.34) in intron 3 of the OTC gene (IVS3-39_40insT) is reported here, and allelic frequencies of 16 additional intragenic OTC polymorphisms are determined in 133-35 (average per polymorphism, 72) unrelated chromosomes. In addition to the novel polymorphism, only three of the studied polymorphisms (Lys46Arg, allelic frequency 0.68/0.32; IVS3-8A>T, 0.34/0.66; Gln270Arg, 0.97/0.03) are confirmed to be informative. These provide, together with another reported polymorphism (IVS4-7A>G; reported allelic frequency 0.71/0.29; Plante and Tuchman, 1998), a set of highly valuable markers of the OTC gene. Nevertheless, the combined informativity of the studied polymorphisms is limited by their distribution in only four haplotypes with one of them predominating (65% of the sampled chromosomes). Although this haplotype composition may be restricted to the Iberian peninsula (the origin of the samples), more informative polymorphisms are required to increase the diagnostic potential and, particularly, to identify large deletions affecting OTC gene exons 5-10, where only one polymorphism of weak diagnostic value is known. © 2002 Wiley-Liss, Inc. [source] Dihydropyrimidine dehydrogenases and cytidine-deaminase gene polymorphisms as outcome predictors in resected gastric cancer patients treated with fluoropyrimidine adjuvant chemotherapyJOURNAL OF SURGICAL ONCOLOGY, Issue 2 2008Juan J. Grau MD Abstract Background and Objectives Single nucleotide polymorphisms of dihydropyrimidine dehydrogenases gene (DPYD) induces dihydropyrimidine dehydrogenase enzyme (DPD) deficiency resulting in increased activity of 5-fluorouracil derivatives. Cytidine-deaminase gene (CDA) polymorphisms have been involved in prognosis in experimental tumours. Methods Analysis of 50 consecutive resected gastric cancer patients who received adjuvant chemotherapy with Tegafur for polymorphisms of genes DPYD1 (A/G; Ile543Val), DPYD2 (C/T; Arg29Cys) and CDA (A/C; Lys27Gin). The status of alleles (wild-type or at least one polymorphism) was correlated with outcome and toxicity. Results Polymorphisms frequencies wild-type/non-wild-type were 36/14 in DPYD1 (A/G; Ile543Val); 26/24 in DPYD2 (C/T; Arg29Cys); and 17/23 in CDA (A/C; Lys27Gin) or between homozygous/heterozygous were 39/11 in DPYD1; 33/17 in DPYD2 and 26/24 in CDA respectively. After 77 months of median follow-up (SD,=,26.3), 18 patients died of tumour relapse. Better survival was observed in DPYD1 patients only, for non-wild-type over wild-type (P,=,0.0214); and in patients with one or more heterozygous polymorphisms in any of the three genes tested (P,=,0.0017). In 10 pts (20%) total dose was reduced by toxicity, only 3 of them were homozygous. Conclusions Gene polymorphisms of DPYD and CDA predict survival of gastric cancer patients treated with 5-fluorouracil-based adjuvant chemotherapy. J. Surg. Oncol. 2008;98:130,134. © 2008 Wiley-Liss, Inc. [source] Adaptation of the extended transmission/disequilibrium test to distinguish disease associations of multiple loci: the Conditional Extended Transmission/Disequilibrium TestANNALS OF HUMAN GENETICS, Issue 3 2000B. P. C. KOELEMAN Linkage and association studies in complex diseases are used to identify and fine map disease loci. The process of identifying the aetiological polymorphism, the molecular variant responsible for the linkage and association of the chromosome region with disease, is complicated by the low penetrance of the disease variant, the linkage disequilibrium between physically-linked polymorphic markers flanking the disease variant, and the possibility that more than one polymorphism in the most associated region is aetiological. It is important to be able to detect additional disease determinants in a region containing a cluster of genes, such as the major histocompatibility complex (MHC) region on chromosome 6p21. Some methods have been developed for detection of additional variants, such as the Haplotype Method, Marker Association Segregation Chi-squares (MASC) Method, and the Homozygous Parent Test. Here, the Extended Transmission/Disequilibrium Test is adapted to test for association conditional on a previously associated locus. This test is referred to as the Conditional Extended TDT (CETDT). We discuss the advantages of the CETDT compared to existing methods and, using simulated data, investigate the effect of polymorphism, inheritance, and linkage disequilibrium on the CETDT. [source] | ||||||||||