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91.
Grace PM Hurley D Barratt DT Tsykin A Watkins LR Rolan PE Hutchinson MR 《Journal of neurochemistry》2012,122(5):976-994
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Rat liver casein kinase TS (Ck-TS) having quarternary structure α2β2, autophosphorylates at its 25 kDa, β-subunits, incorporating up to 1.2 mol P/mol enzyme. According to their effects on the autophosphorylation pattern the effectors of Ck-TS activity can be grouped into 3 classes: (i) inhibitors, like heparin, which also prevent the autophosphorylation of the β-subunit; (ii) stimulators possessing several amino groups (like spermine) which increase the autophosphorylation at the β-subunit; (iii) stimulators possessing several guanido groups, like protamines and related peptides, which prevent the phosphorylation of the β-subunit, while promoting the autophosphorylation of the 38 kDa α-subunit. In the presence of such polyarginyl effectors the 130 kDa Ck-TS is converted into forms with higher sedimentation coefficient. 相似文献
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Nichola A. Strandberg Mary Edwards Joanna C. Ellison Manuel J. Steinbauer Anna Walentowitz Patricia L. Fall David Sear Peter Langdon Shane Cronin Alvaro Castilla-Beltrán Ian W. Croudace Matiu Prebble William D. Gosling Sandra Nogué 《Biotropica》2023,55(4):816-827
Here, we investigate Mid- to Late-Holocene vegetation changes in low-lying coastal areas in Tonga and how changing sea levels and recurrent volcanic eruptions have influenced vegetation dynamics on four islands of the Tongan archipelago (South Pacific). To investigate past vegetation and environmental change at Ngofe Marsh (‘Uta Vava’u), we examined palynomorphs (pollen and spores), charcoal (fire), and sediment characteristics (volcanic activity) from a 6.7-m-long sediment core. Radiocarbon dating indicated the sediments were deposited over the last 7700 years. We integrated the Ngofe Marsh data with similar previously published data from Avai’o’vuna Swamp on Pangaimotu Island, Lotofoa Swamp on Foa Island, and Finemui Swamp on Ha’afeva Island. Plant taxa were categorized as littoral, mangrove, rainforest, successional/ disturbance, and wetland groups, and linear models were used to examine relationships between vegetation, relative sea level change, and volcanic eruptions (tephra). We found that relative sea level change has impacted vegetation on three of the four islands investigated. Volcanic eruptions were not identified as a driver of vegetation change. Rainforest decline does not appear to be driven by sea level changes or volcanic eruptions. From all sites analyzed, vegetation at Finemui Swamp was most sensitive to changes in relative sea level. While vegetation on low-lying Pacific islands is sensitive to changing sea levels, island characteristics, such as area and elevation, are also likely to be important factors that mediate specific island responses to drivers of change. 相似文献
96.
Pogribny IP Tryndyak VP Boureiko A Melnyk S Bagnyukova TV Montgomery B Rusyn I 《Mutation research》2008,644(1-2):17-23
Genomic hypomethylation is a consistent finding in both human and animal tumors and mounting experimental evidence suggests a key role for epigenetic events in tumorigenesis. Furthermore, it has been suggested that early changes in DNA methylation and histone modifications may serve as sensitive predictive markers in animal testing for carcinogenic potency of environmental agents. Alterations in metabolism of methyl donors, disturbances in activity and/or expression of DNA methyltransferases, and presence of DNA single-strand breaks could contribute to the loss of cytosine methylation during carcinogenesis; however, the precise mechanisms of genomic hypomethylation induced by chemical carcinogens remain largely unknown. This study examined the mechanism of DNA hypomethylation during hepatocarcinogenesis induced by peroxisome proliferators WY-14,643 (4-chloro-6-(2,3-xylidino)-pyrimidynylthioacetic acid) and DEHP (di-(2-ethylhexyl)phthalate), agents acting through non-genotoxic mode of action. In the liver of male Fisher 344 rats exposed to WY-14,643 (0.1% (w/w), 5 months), the level of genomic hypomethylation increased by approximately 2-fold, as compared to age-matched controls, while in the DEHP group (1.2% (w/w), 5 months) DNA methylation did not change. Global DNA hypomethylation in livers from WY-14,643 group was accompanied by the accumulation of DNA single-strand breaks, increased cell proliferation, and diminished expression of DNA methyltransferase 1, while the metabolism of methyl donors was not affected. In contrast, none of these parameters changed significantly in rats fed DEHP. Since WY-14,643 is much more potent carcinogen than DEHP, we conclude that the extent of loss of DNA methylation may be related to the carcinogenic potential of the chemical agent, and that accumulation of DNA single-strand breaks coupled to the increase in cell proliferation and altered DNA methyltransferase expression may explain genomic hypomethylation during peroxisome proliferator-induced carcinogenesis. 相似文献
97.
Ihnatowicz A Pesaresi P Varotto C Richly E Schneider A Jahns P Salamini F Leister D 《The Plant journal : for cell and molecular biology》2004,37(6):839-852
In Arabidopsis thaliana, the D-subunit of photosystem I (PSI-D) is encoded by two functional genes, PsaD1 and PsaD2, which are highly homologous. Knock-out alleles for each of the loci have been identified by a combination of forward and reverse genetics. The double mutant psad1-1 psad2-1 is seedling-lethal, high-chlorophyll-fluorescent and deficient for all tested PSI subunits, indicating that PSI-D is essential for photosynthesis. In addition, psad1-1 psad2-1 plants show a defect in the accumulation of thylakoid multiprotein complexes other than PSI. Of the single-gene mutations, psad2 plants behave like wild-type (WT) plants, whereas psad1-1 markedly affects the accumulation of PsaD mRNA and protein, and photosynthetic electron flow. Additional effects of the psad1-1 mutation include a decrease in growth rate under greenhouse conditions and downregulation of the mRNA expression of most genes involved in the light phase of photosynthesis. In the same mutant, a marked decrease in the levels of PSI and PSII polypeptides is evident, as well as a light-green leaf coloration and increased photosensitivity. Increased dosage of PsaD2 in the psad1-1 background restores the WT phenotype, indicating that PSI-D1 and PSI-D2 have redundant functions. 相似文献
98.
Lubiński J Górski B Kurzawski G Jakubowska A Cybulski C Suchy J Debniak T Grabowska E Lener M Nej K 《Acta biochimica Polonica》2002,49(3):571-581
On the basis of literature data and own experience the authors review the current knowledge about the molecular basis of inherited predispositions for tumors. They hypothesize that in the near perspective 5-10 years studies using existing registry data/material and the latest novel technology will allow the identification of the molecular background for the majority of hereditary cancers which will have enormous practical consequences especially for the prevention of malignancies. 相似文献
99.
100.
Innala L Möller B Ljung L Magnusson S Smedby T Södergren A Öhman ML Rantapää-Dahlqvist S Wållberg-Jonsson S 《Arthritis research & therapy》2011,13(4):R131