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Mutational Load (mutational + load)
Selected AbstractsIdentifying genetic components controlling fertility in the outcrossing grass species perennial ryegrass (Lolium perenne) by quantitative trait loci analysis and comparative geneticsNEW PHYTOLOGIST, Issue 3 2008I. P. Armstead Summary ,,Mutational load and resource allocation factors and their effects on limiting seed set were investigated in ryegrass by comparative mapping genomics and quantitative trait loci (QTL) analysis in two perennial ryegrass (Lolium perenne) mapping families sharing common genetic markers. ,,Quantitative trait loci for seed-set were identified on chromosome (LG) 7 in both families and on LG4 of the F2/WSC family. On LG7, seed-set and heading date QTLs colocalized in both families and cannot be unequivocally resolved. Comparative genomics suggests that the LG7 region is syntenous to a region of rice LG6 which contains both fertility (S5n) and heading date (Hd1, Hd3a) candidate genes. The LG4 region is syntenous to a region of rice LG3 which contains a fertility (S33) candidate gene. QTL maxima for seed-set and heading date on LG4 in the F2/WSC family are separated by c. 8 cm, indicating distinct genetic control. ,,Low seed set is under the control of recessive genes at both LG4 and LG7 locations. ,,The identification of QTLs associated with seed set, a major component of seed yield in perennial ryegrass, indicates that mutational load associated with these genomic regions can be mitigated through marker-assisted selection. [source] Absence of acute apoptotic response to genotoxic carcinogens in p53 -deficient mice is associated with increased susceptibility to azoxymethane-induced colon tumoursINTERNATIONAL JOURNAL OF CANCER, Issue 4 2005Ying Hu Abstract Acute apoptotic response to genotoxic carcinogens (AARGC) might be important for controlling the consequences of mutational load in the colon. It has been shown to occur in parallel with activation of DNA repair mechanisms. Inadequate AARGC might allow development of mutated clones with the potential to progress to cancer. In this study, we tested if p53 levels were important for AARGC in the colon and whether defective AARGC was associated with increased risk for colorectal oncogenesis. Apoptosis was measured in colonic epithelium of mice from each p53 genotype (p53,/,, p53+/,, wild-type) without and 8 hr following a single injection of azoxymethane (AOM). To determine risk for carcinogen-induced colorectal cancer (CRC), groups of mice from each p53 genotype received 3 weekly injections of AOM and colons were examined for tumour 20 weeks later. Rates of spontaneous apoptosis in colon were not affected by p53 level. However, AARGC was absent in p53,/, mice and reduced by 50% in p53+/, mice (both p < 0.01) compared to wild-type mice. AOM induced tumours in 30% of wild-type mice (average multiplicity 1.0 tumours/mouse) compared to 72% of p53+/, mice (2.0 tumours/mouse, p < 0.01) and 100% of p53,/, mice (2.8 tumours/mouse, p < 0.01). Without AOM, significantly fewer mice in all groups had tumours. Rates of apoptosis in tumours were independent of p53 status. p53 dysfunction puts intestinal epithelia at increased risk of genotoxin-induced oncogenesis due to impairment of apoptotic response mechanisms. p53 levels do not appear, however, to be important for spontaneous apoptosis in normal epithelium or apoptosis in tumours. Subsequent studies are now warranted to test the converse, namely, that enhanced apoptotic response to carcinogen reduces risk for colorectal oncogenesis. © 2005 Wiley-Liss, Inc. [source] Effect of male age on sperm traits and sperm competition success in the guppy (Poecilia reticulata)JOURNAL OF EVOLUTIONARY BIOLOGY, Issue 1 2010C. GASPARINI Abstract Deleterious mutations can accumulate in the germline with age, decreasing the genetic quality of sperm and imposing a cost on female fitness. If these mutations also affect sperm competition ability or sperm production, then females will benefit from polyandry as it incites sperm competition and, consequently, minimizes the mutational load in the offspring. We tested this hypothesis in the guppy (Poecilia reticulata), a species characterized by polyandry and intense sperm competition, by investigating whether age affects post-copulatory male traits and sperm competition success. Females did not discriminate between old and young males in a mate choice experiment. While old males produced longer and slower sperm with larger reserves of strippable sperm, compared to young males, artificial insemination did not reveal any effect of age on sperm competition success. Altogether, these results do not support the hypothesis that polyandry evolved in response to costs associated with mating with old males in the guppy. [source] Fractional allelic imbalance could allow for the development of an equitable transplant selection policy for patients with hepatocellular carcinomaLIVER TRANSPLANTATION, Issue 4 2008Igor Dvorchik Liver transplantation (LT) in the presence of hepatocellular carcinoma (HCC) remains a controversial issue because the current staging systems are not sufficiently predictive of outcomes. Paraffin blocks from 183 patients that underwent LT in the presence of HCC were collected. Molecular analysis was carried out blindly on the native liver specimens in all cases with respect to recurrence outcomes. The fractional allelic imbalance (FAI) rate index was determined in each case and was used to compare the acquired mutational load between different tumors. The FAI was determined from the microdissected tissue site displaying the greatest amount of acquired allelic loss. FAI was found to be the strongest predictor of recurrence followed by vascular invasion and then by tumor number or hepatic lobar involvement. Based on these findings, 3 prognostic models were constructed for selection of candidates for LT in patients with concomitant HCC. Molecular markers of tumor progression are the strongest predictors of HCC recurrence currently available, surpassing all components of the tumor-node-metastasis classification system for staging of malignant tumors (TNM), including vascular invasion. Incorporation of these molecular markers of tumor progression could help resolve the ongoing conundrum of organ allocation for patients with HCC. Liver Transpl 2007. © 2007 AASLD. [source] Identifying genetic components controlling fertility in the outcrossing grass species perennial ryegrass (Lolium perenne) by quantitative trait loci analysis and comparative geneticsNEW PHYTOLOGIST, Issue 3 2008I. P. Armstead Summary ,,Mutational load and resource allocation factors and their effects on limiting seed set were investigated in ryegrass by comparative mapping genomics and quantitative trait loci (QTL) analysis in two perennial ryegrass (Lolium perenne) mapping families sharing common genetic markers. ,,Quantitative trait loci for seed-set were identified on chromosome (LG) 7 in both families and on LG4 of the F2/WSC family. On LG7, seed-set and heading date QTLs colocalized in both families and cannot be unequivocally resolved. Comparative genomics suggests that the LG7 region is syntenous to a region of rice LG6 which contains both fertility (S5n) and heading date (Hd1, Hd3a) candidate genes. The LG4 region is syntenous to a region of rice LG3 which contains a fertility (S33) candidate gene. QTL maxima for seed-set and heading date on LG4 in the F2/WSC family are separated by c. 8 cm, indicating distinct genetic control. ,,Low seed set is under the control of recessive genes at both LG4 and LG7 locations. ,,The identification of QTLs associated with seed set, a major component of seed yield in perennial ryegrass, indicates that mutational load associated with these genomic regions can be mitigated through marker-assisted selection. [source] Platelet turnover, coagulation factors, and soluble markers of platelet and endothelial activation in essential thrombocythemia: Relationship with thrombosis occurrence and JAK2 V617F allele burden,AMERICAN JOURNAL OF HEMATOLOGY, Issue 2 2009Eduardo Arellano-Rodrigo Patients with essential thrombocythemia (ET) have an increased frequency of thrombosis, but the relationship of both thrombosis and JAK2 V617F allele burden with platelet turnover, acquired activated protein C resistance (aAPCR), and levels of coagulation factors and soluble markers of platelet, and endothelial activation is not well known. In 53 ET patients (26 with a history of thrombosis), reticulated platelets (RP) percentage, aAPCR, platelet tissue factor (TF) expression, and plasma levels of TF, coagulation factors, soluble P-selectin (sP-selectin), soluble CD40 ligand (sCD40L), von Willebrand factor antigen (VWF:Ag), soluble thrombomodulin (sTM), D -dimer and prothrombin fragment 1 + 2 were compared with those in matched healthy individuals and correlated with thrombosis occurrence and JAK2 mutational load. ET patients with thrombosis had significantly higher values for RP percentage, aAPCR, and levels of factors V and VIII, VWF:Ag, sP-selectin, and sCD40L than patients without thrombosis and controls. At multivariate study, RP percentage, factor V levels, and aAPCR were independently associated with an increased risk of thrombosis. Patients with JAK2 mutation had significantly lower levels of free protein S (PS) and higher levels of TF, sP-selectin, sCD40L, VWF:Ag, and sTM than those with wild-type allele. A mutant allele dosage effect (, 12%) was observed for TF, sP-selectin, sCD40L, VWF:Ag, and PS levels. These results support a role for platelet turnover, factor V, and aAPCR in the thrombosis of ET as well as the association between JAK2 V617F allele burden and either decreased free PS or increased TF and soluble markers of platelet and endothelial activation. Am. J. Hematol., 2009. © 2008 Wiley-Liss, Inc. [source] 2466: Blue cone nonochromacy gene mutation in Asia: phenotype variabilityACTA OPHTHALMOLOGICA, Issue 2010P BITOUN Purpose A far East asian family with 4 affected maternal cousin males with congenital nystagmus, low vision and dyschromatopsia was investigated for a genetic cause after informed consent. Blue cone monochromacy is a rare form of X-linked visual handicap with dyschromatopsia. Methods Family members had ophthalmologic examination including visual acuity, fundoscopy , slit lamp, biomicroscopy,colour vision testing and ERG and VEP recordings.DNA analysis of the composition of the cone ospin gene cluster was performed by PCR and PCR/RFLP as well as direct sequencing of LWS opsin gene. Results A novel nonsense Mutation in the single Long wave sensitive opsin gene was identified in all affected males and carrier females. The variability of the phenotype as well as the added role of parental myopia transmission in the phenotype will be discussed. Conclusion This is the first reported molecular diagnosis of blue cone monochromacy in the Asian population. The compound effect of dominantly inherited myopia offers insight of the effect of the added mutational load in these patients. [source] | |||||||||||||