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Compared with our knowledge of senescence in annuals and biennials, little is known about age-related changes in perennials.
To get new insights into the mechanisms underlying aging in perennials, we measured oxidative stress markers in leaves and
organelles, together with abscisic acid levels in leaves of 2- and 7-year-old Cistus clusii dunal plants grown under Mediterranean field conditions. Recently emerged leaves, which either appeared during autumn or
spring, were compared to evaluate the effects of environmental constraints on oxidative stress and abscisic acid accumulation
as plants aged. Plant aging led to an enhanced oxidation of α-tocopherol and ascorbate, increased lipid peroxidation and reduced
PSII efficiency in leaves during the more stressful conditions of spring and summer, but not during autumn. Analyses of lipid
peroxidation in organelles isolated from the same leaves revealed that oxidative stress occurred both in chloroplasts and
mitochondria. Although both plant groups showed similar leaf water and nitrogen contents throughout the study, abscisic acid
levels were markedly higher (up to 75%) in 7-year-old plants compared to 2-year-old plants throughout the study. It is concluded
that (a) meristematic tissues of C. clusii maintain the capacity to make new leaves with no symptoms of oxidative stress for several years, unless these leaves are
exposed to environmental constraints, (b) leaves of oldest plants show higher oxidative stress than those of young plants
when exposed to adverse climatic conditions, thus supporting the idea that the oxidative stress associated with aging is due
at least partly to extrinsic factors, (c) at the subcellular level, age-induced oxidative stress occurs both in chloroplasts
and mitochondria, and (d) even in the absence of environmental stress, newly emerged leaves accumulate higher amounts of ABA
as plants age. 相似文献
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Background
The trithorax group (trxG) genes absent, small or homeotic discs 1 (ash1) and 2 (ash2) were isolated in a screen for mutants with abnormal imaginal discs. Mutations in either gene cause homeotic transformations but Hox genes are not their only targets. Although analysis of double mutants revealed that ash2 and ash1 mutations enhance each other's phenotypes, suggesting they are functionally related, it was shown that these proteins are subunits of distinct complexes. 相似文献34.
Tornés Elisabet Alández-Rodríguez Juan Corrochano Alfredo Nolla-Querol Pepita Trapote Maria Carmen Sabater Sergi 《Hydrobiologia》2022,849(8):1821-1837
Hydrobiologia - Consequences of anthropogenic climate change directly affect freshwater ecosystems and their aquatic biological communities. Diatoms are amongst the most sensitive organisms to... 相似文献
35.
Background and Aims Vitamin E helps to control the cellular redox state by reacting with singlet oxygen and preventing the propagation of lipid peroxidation in thylakoid membranes. Both plant ageing and phosphorus deficiency can trigger accumulation of reactive oxygen species, leading to damage to the photosynthetic apparatus. This study investigates how phosphorus availability and vitamin E interact in the control of plant longevity in the short-lived annual Arabidopsis thaliana.Methods The responses of tocopherol cyclase (VTE1)- and γ-tocopherol methyltransferase (VTE4)-null mutants to various levels of phosphorus availability was compared with that of wild-type plants. Longevity (time from germination to rosette death) and the time taken to pass through different developmental stages were determined, and measurements were taken of photosynthetic efficiency, pigment concentration, lipid peroxidation, vitamin E content and jasmonate content.Key Results The vte1 mutant showed accelerated senescence under control conditions, excess phosphorus and mild phosphorus deficiency, suggesting a delaying, protective effect of α-tocopherol during plant senescence. However, under severe phosphorus deficiency the lack of α-tocopherol paradoxically increased longevity in the vte1 mutant, while senescence was accelerated in wild-type plants. Reduced photoprotection in vitamin E-deficient mutants led to increased levels of defence chemicals (as indicated by jasmonate levels) under severe phosphorus starvation in the vte4 mutant and under excess phosphorus and mild phosphorus starvation in the vte1 mutant, indicating a trade-off between the capacity for photoprotection and the activation of chemical defences (jasmonate accumulation).Conclusions Vitamin E increases plant longevity under control conditions and mild phosphorus starvation, but accelerates senescence under severe phosphorus limitation. Complex interactions are revealed between phosphorus availability, vitamin E and the potential to synthesize jasmonates, suggesting a trade-off between photoprotection and the activation of chemical defences in the plants. 相似文献
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Pressure pain threshold of the cervico‐facial muscles in healthy elderly people: the role of gender,age and dominance
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Tomlinson IP Carvajal-Carmona LG Dobbins SE Tenesa A Jones AM Howarth K Palles C Broderick P Jaeger EE Farrington S Lewis A Prendergast JG Pittman AM Theodoratou E Olver B Walker M Penegar S Barclay E Whiffin N Martin L Ballereau S Lloyd A Gorman M Lubbe S;COGENT Consortium;CORGI Collaborators;EPICOLON Consortium Howie B Marchini J Ruiz-Ponte C Fernandez-Rozadilla C Castells A Carracedo A Castellvi-Bel S Duggan D Conti D Cazier JB Campbell H Sieber O Lipton L Gibbs P Martin NG Montgomery GW 《PLoS genetics》2011,7(6):e1002105
Genome-wide association studies (GWAS) have identified 14 tagging single nucleotide polymorphisms (tagSNPs) that are associated with the risk of colorectal cancer (CRC), and several of these tagSNPs are near bone morphogenetic protein (BMP) pathway loci. The penalty of multiple testing implicit in GWAS increases the attraction of complementary approaches for disease gene discovery, including candidate gene- or pathway-based analyses. The strongest candidate loci for additional predisposition SNPs are arguably those already known both to have functional relevance and to be involved in disease risk. To investigate this proposition, we searched for novel CRC susceptibility variants close to the BMP pathway genes GREM1 (15q13.3), BMP4 (14q22.2), and BMP2 (20p12.3) using sample sets totalling 24,910 CRC cases and 26,275 controls. We identified new, independent CRC predisposition SNPs close to BMP4 (rs1957636, P = 3.93×10(-10)) and BMP2 (rs4813802, P = 4.65×10(-11)). Near GREM1, we found using fine-mapping that the previously-identified association between tagSNP rs4779584 and CRC actually resulted from two independent signals represented by rs16969681 (P = 5.33×10(-8)) and rs11632715 (P = 2.30×10(-10)). As low-penetrance predisposition variants become harder to identify-owing to small effect sizes and/or low risk allele frequencies-approaches based on informed candidate gene selection may become increasingly attractive. Our data emphasise that genetic fine-mapping studies can deconvolute associations that have arisen owing to independent correlation of a tagSNP with more than one functional SNP, thus explaining some of the apparently missing heritability of common diseases. 相似文献