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Possible Genotype (possible + genotype)
Selected AbstractsADAPTIVE EVOLUTION OF ASEXUAL POPULATIONS UNDER MULLER'S RATCHETEVOLUTION, Issue 7 2004Doris Bachtrog Abstract We study the population genetics of adaptation in nonequilibrium haploid asexual populations. We find that the accumulation of deleterious mutations, due to the operation of Muller's ratchet, can considerably reduce the rate of fixation of advantageous alleles. Such reduction can be approximated reasonably well by a reduction in the effective population size. In the absence of Muller's ratchet, a beneficial mutation can only become fixed if it creates the best possible genotype; if Muller's ratchet operates, however, mutations initially arising in a nonoptimal genotype can also become fixed in the population, since the loss of the least-loaded class implies that an initially nonoptimal background can become optimal. We show that, while the rate at which adaptive mutations become fixed is reduced, the rate of fixation of deleterious mutations due to the ratchet is not changed by the presence of beneficial mutations as long as the rate of their occurrence is low and the deleterious effects of mutations (sd) are higher than the beneficial effects (sa). When sa>sd, the advantage of a beneficial mutation can outweigh the deleterious effects of associated mutations. Under these conditions, a beneficial allele can drag to fixation deleterious mutations initially associated with it at a higher rate than in the absence of advantageous alleles. We propose analytical approximations for the rates of accumulation of deleterious and beneficial mutations. Furthermore, when allowing for the possible occurrence of interference between beneficial alleles, we find that the presence of deleterious mutations of either very weak or very strong effect can marginally increase the rate of accumulation of beneficial mutations over that observed in the absence of such deleterious mutations. [source] One gene, two phenotypes: ROR2 mutations in autosomal recessive Robinow syndrome and autosomal dominant brachydactyly type B,HUMAN MUTATION, Issue 1 2003Ali R. Afzal Abstract Autosomal recessive Robinow syndrome (RRS) is a severe skeletal dysplasia with short stature, generalized limb shortening, segmental defects of the spine, brachydactyly, and a dysmorphic facial appearance. The gene encoding receptor orphan receptor tyrosine kinase 2 (ROR2) is located on chromosome 9q22 and homozygous loss-of-function mutations in this gene are responsible for RRS. Moreover, knocking out the mouse Ror2 gene causes mesomelic dwarfism in the homozygous state, with almost identical features to recessive Robinow syndrome. The protein product of this gene is a cell membrane receptor, containing distinct motifs including an immunoglobulin-like (Ig) domain, a Frizzled-like cysteine-rich domain (FRZ or CRD), and a kringle domain (KD) in the extracellular region; and an intracellular region with tyrosine kinase (TK), serine/threonine-rich, and proline-rich structures. The extracellular motifs of the ROR2 protein are known to be involved in protein,protein interactions. The tyrosine kinase domain is involved in an as yet uncharacterized signaling pathway. Interestingly, heterozygous mutations in ROR2 have recently been shown to give rise to autosomal dominant brachydactyly type B1 (BDB1). This condition is characterized by terminal deficiency of fingers and toes. A variety of mutations have been reported in ROR2. Here, these genetic defects are compiled and possible genotype,phenotype correlations are discussed. Hum Mutat 22:1,11, 2003. © 2003 Wiley-Liss, Inc. [source] Development and variability analysis of microsatellite markers in peachPLANT BREEDING, Issue 1 2002M. J. Aranzana Abstract A genomic DNA library enriched with AG/CT repeats has been developed from the peach cultivar ,Merrill O'Henry'. The enrichment method was efficient, with 61% of the clones obtained carrying a microsatellite sequence and a yield of one polymorphic microsatellite every 2.17 sequenced clones. From 35 microsatellites detected, 24 were polymorphic in a set of 25 cultivars including 14 peaches and 11 nectarines. A total of 82 alleles were found with the polymorphic microsatellites, with an average of a 37% of observed heterozygosity. Microsatellites with a high number of repeats were generally those having the largest number of alleles. All cultivars except two (,Spring Lady' and ,Queencrest') could be individually distinguished with the markers used. Just three selected microsatellites were enough for the discrimination of 24 out of the 25 possible genotypes. Cluster analysis grouped all nectarines in a single cluster. Peaches, with 75 of the 82 alleles found, were more variable than nectarines, with only 64. Microsatellites appear to be powerful and suitable markers for application in peach genetics and breeding. [source] ORIGINAL ARTICLE: Leptin Gene (TTTC)n Microsatellite Polymorphism as well as Leptin Receptor R223Q and PPAR,2 P12A Substitutions are not Associated with Hypertensive Disorders in PregnancyAMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 4 2010Annette Wiedemann Citation Wiedemann A, Vocke F, Fitzgerald JS, Markert UR, Jeschke U, Lohse P, Toth B. Leptin gene (TTTC)n microsatellite polymorphism as well as Leptin receptor R223Q and PPAR,2 P12A substitutions are not associated with hypertensive disorders in pregnancy. Am J Reprod Immunol 2010; 63: 310,317 Problem, Pregnancy-induced hypertension (PIH) affects up to 15% of all pregnancies. Disturbed placentation is one factor associated with PIH. Leptin and peroxisome proliferator activator receptors (PPAR) seem to play an important role in placentation, fetal development, and blood pressure regulation. Therefore, we investigated polymorphisms in the genes encoding leptin, the leptin receptor, and PPAR,2 in patients with PIH. Method of study, In this retrospective case,control study, 103 patients with PIH [gestational hypertension (GH) n = 39; preeclampsia n = 27; eclampsia n = 5; HELLP n = 32] and 100 controls were analyzed for the LEP tetranucleotide repeat (TTTC)n and the leptin receptor (LEPR) R223Q and PPAR,2 P12A substitutions. Statistical analysis was performed using the chi-square, Mann,Whitney U -, and Kruskal,Wallis tests (P < 0.05 significant). Results, The frequency of the three possible genotypes did not differ significantly between patients and controls [LEP (TTTC)n: P = 0.43; LEPR R223Q: P = 0.94; PPAR,2 P12A: P = 0.94]. However, postpartal diastolic blood pressure of PIH patients was significantly higher in homozygous carriers of the LEPR Q223-encoding allele as compared with patients carrying the wild-type allele (P < 0.01). Conclusion, Hypertensive disorders in pregnancy were not associated with the LEP, LEPR, and PPAR,2 polymorphisms studied. The role of other variations in the LEP and PPAR genes in the pathophysiology of PIH and in exacerbations are the objective of ongoing research. [source] | ||||||||||