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Previous Genetic Analyses (previous + genetic_analysis)
Selected AbstractsSignaling requirements and role of salicylic acid in HRT - and rrt -mediated resistance to turnip crinkle virus in ArabidopsisTHE PLANT JOURNAL, Issue 5 2004A.C. Chandra-Shekara Summary Inoculation of turnip crinkle virus (TCV) on the resistant Arabidopsis ecotype Di-17 elicits a hypersensitive response (HR), which is accompanied by increased expression of pathogenesis-related (PR) genes. Previous genetic analyses revealed that the HR to TCV is conferred by HRT, which encodes a coiled-coil (CC), nucleotide-binding site (NBS) and leucine-rich repeat (LRR) class resistance (R) protein. In contrast to the HR, resistance to TCV requires both HRT and a recessive allele at a second locus designated rrt. Here, we demonstrate that unlike most CC-NBS-LRR R genes, HRT/rrt -mediated resistance is dependent on EDS1 and independent of NDR1. Resistance is also independent of RAR1 and SGT1. HRT/rrt -mediated resistance is compromised in plants with reduced salicylic acid (SA) content as a consequence of mutations eds5, pad4, or sid2. By contrast, HR is not affected by mutations in eds1, eds5, pad4, sid2, ndr1, rar1, or sgt1b. Resistance to TCV is restored in both SA-deficient Di-17 plants expressing the nahG transgene and mutants containing the eds1, eds5, or sid2 mutations by exogenous application of SA or the SA analog benzo(1,2,3)thiadiazole-7-carbothioic acid (BTH). In contrast, SA/BTH treatment failed to enhance resistance in HRT pad4, Col-0, or hrt homozygous progeny of a cross between Di-17 and Col-0. Thus, HRT and PAD4 are required for SA-induced resistance. Exogenously supplied SA or high endogenous levels of SA, due to the ssi2 mutation, overcame the suppressive effects of RRT and enhanced resistance to TCV, provided the HRT allele was present. High levels of SA upregulate HRT expression via a PAD4 -dependent pathway. As Col-0 transgenic lines expressing high levels of HRT were resistant to TCV, but lines expressing moderate to low levels of HRT were not, we conclude that SA enhances resistance in the RRT background by upregulating HRT expression. These data suggest that the HRT-TCV interaction is unable to generate sufficient amounts of SA required for a stable resistance phenotype, and the presence of rrt possibly corrects this deficiency. [source] Regulation of COP1 nuclear localization by the COP9 signalosome via direct interaction with CSN1THE PLANT JOURNAL, Issue 4 2009Xiping Wang Summary COP1 and COP9 signalosome (CSN) are key regulators of plant light responses and development. Deficiency in either COP1 or CSN causes a constitutive photomorphogenic phenotype. Through coordinated actions of nuclear- and cytoplasmic-localization signals, COP1 can respond to light signals by differentially partitions between nuclear and cytoplasmic compartments. Previous genetic analysis in Arabidopsis indicated that the nuclear localization of COP1 requires CSN, an eight-subunit heteromeric complex. However the mechanism underlying the functional relationship between COP1 and CSN is unknown. We report here that COP1 weakly associates with CSN in vivo. Furthermore, we report on the direct interaction involving the coiled-coil domain of COP1 and the N-terminal domain of the CSN1 subunit. In onion epidermal cells, expression of CSN1 can stimulate nuclear localization of GUS-COP1, and the N-terminal domain of CSN1 is necessary and sufficient for this function. Moreover, CSN1-induced COP1 nuclear localization requires the nuclear-localization sequences of COP1, as well as its coiled-coil domain, which contains both the cytoplasmic localization sequences and the CSN1 interacting domain. We also provide genetic evidence that the CSN1 N-terminal domain is specifically required for COP1 nuclear localization in Arabidopsis hypocotyl cells. This study advances our understanding of COP1 localization, and the molecular interactions between COP1 and CSN. [source] Competitive relationships of Andropogon gerardii (Big Bluestem) from remnant and restored native populations and select cultivated varietiesFUNCTIONAL ECOLOGY, Issue 3 2004D. J. GUSTAFSON Summary 1Although genetic differentiation among plant populations is well known, its relevance for preserving the integrity of native ecosystems has received little attention. In a series of competition experiments with Andropogon gerardii Vitman, a dominant species of the North American Tallgrass Prairie, plant performance was related to seed provenance and restoration activities. 2Glasshouse experiments showed plant performance to be a function of seed source. Differential target plant performance relative to competitor identity was observed when plant performance was assessed across a range of competitor densities. Local and non-local plants were larger when competing against non-local plants relative to the local and cultivar plants, while cultivar plants were consistently larger than local and non-local plants regardless of competitor identity or density. The consistency of cultivar performance could reflect directional selection during cultivar development for consistently high fecundity, vigorous vegetative growth and resistance to pathogens. 3In a field experiment, non-local plants were half the size of local and cultivar plants, supporting recognition of seed provenances of A. gerardii based on differences in plant performance among source populations observed in the glasshouse study, and previous genetic analyses of the same populations. 4This study establishes that seed provenance and restoration activities influence the competitive ability of a dominant species which, in turn, may affect plant community structure and potential ecosystem function. [source] Environment-related life-history trait variations of the red-bellied piranha Pygocentrus nattereri in two river basins of the Bolivian AmazonJOURNAL OF FISH BIOLOGY, Issue 4 2007F. Duponchelle Life-history traits of Pygocentrus nattereri were compared in two populations inhabiting connected tributaries of the upper Madera River: the white water Mamoré River and the clear water Iténez River. As white waters provide better trophic conditions than clear waters, the size at maturity, fecundity, reproductive effort, condition and growth of P. nattereri should be greater in the more productive white water river (Mamoré) than in the less-productive clear water river (Iténez). Breeding periods were highly seasonal and similar in both rivers and under strong influence of photoperiod. Oocyte size-frequency distributions, together with the frequent occurrence of recovering females indicated that an individual female spawns at least twice during the breeding season. As predicted, fish of the Mamoré were significantly larger at maturity and had higher fecundity and condition factor values than those of the Iténez. Fish from both rivers matured as yearlings. The higher growth potential of females was better expressed in the Mamoré than in the Iténez, where growth differences between sexes were weak. Females had a significantly better growth in the Mamoré than in the Iténez. The observed life-history traits associations were consistent with the hypothesis of better trophic conditions in the Mamoré. In addition, previous genetic analyses evidenced that the colonization of the two basins is recent and that extant populations have very similar genetic backgrounds. This suggests that the observed variations in life-history traits of P. nattereri are not related to historical factors (genetic drift) between two phylogeographically distinct lineages, but rather due to the contrasting environmental conditions in the white and clear waters. [source] The D4Mit12 locus on mouse chromosome 4 provides susceptibility to both ,-ray-induced and N-methyl-N-nitrosourea-induced thymic lymphomasCANCER SCIENCE, Issue 8 2003Hiroki Sato Low-penetrance genes control different susceptibilities to ,-ray-induced thymic lymphomas in mouse strains. Our previous genetic analyses with backcross mice between BALB/c and MSM strains and congenic lines localized one such gene near the D4Mit12 locus on chromosome 4. N-Methyl-N-nitrosourea (MNU) is a guanine base-alkylating agent and differs from ,-radiation in its mechanism of mutagenic action. Accordingly, in this study, we examined whether or not the locus also provides susceptibility to MNU-induced thymic lymphomas using 84 offsprings derived from congenic mice for D4Mit12. Association analysis provided a suggestive linkage at D4Mit12 (P=0.0075) and the linkage was sustained by the peak of likelihood ratio statistical values being at the same position as that for the ,-ray-induced lymphomas. The results strongly suggest that the BALB/c allele near D4Mit12 is associated with susceptibility to lymphomas induced by two carcinogenic agents having different mechanisms of mutagenic action. [source] An Expanded Evaluation of the Relationship of Four Alleles to the Level of Response to Alcohol and the Alcoholism RiskALCOHOLISM, Issue 1 2005Xianzhang Hu Background: Alcoholism is a complex, genetically influenced disorder the cause of which may be better understood through the study of genetically influenced phenotypes that mediate the risk. One such intermediate phenotype is the low level of response (LR) to alcohol. This project used a case-control approach to search for genes that may contribute to LR. Methods: Data were available from alcohol challenges at approximately age 20 and regarding the development of alcohol use disorders over the subsequent 20 years for 85 men, including 40 reported in a previous genetic analysis. LR was evaluated using oral consumption of 0.75 ml/kg of alcohol, after which changes in subjective feelings of intoxication and body sway were measured. Alcohol abuse and dependence were diagnosed by DSM-III-R criteria through structured interviews administered to both the participant and an informant (usually the spouse) 10, 15, and 20 years after initial testing. Four polymorphisms were evaluated, including the serotonin transporter HTTLPR promoter ins/del, GABAA,6 Pro385Ser, NPY Leu7Pro, and catalase 262C>T. Two of these, HTTLPR and GABAA,6 Pro385Ser, had been previously associated with LR and alcoholism in a preliminary study. Results: The HTTLPR L allele was significantly related to both the LR and alcoholism in an allele-dosage (stepwise) manner. Furthermore, the association remained when L alleles were subdivided into recently reported functional subtypes: the lowest LR was associated with genotypes correlated with the highest serotonin transporter expression. The GABAA,6 Ser385 allele showed a nonsignificant trend for association to a low LR, as had been previously observed, although the Ser385 allele is uncommon, and only 18 heterozygotes were in the current group. However, the six men with both LL and Pro385/Ser385 genotypes had the lowest LR, and each had developed alcoholism during follow-up. Neither NPY nor catalase was associated with either LR or alcoholic outcomes, although the sample did not have sufficient power for definitive conclusions. Conclusions: This report strengthens the support for a relationship between the HTTLPR L and GABAA,6 Ser385 alleles to low alcohol LR and to alcoholism in a prospectively studied cohort evaluated for LR in young adulthood and before the onset of alcohol dependence. [source] | |||||||||||||