ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • DNA Glycosylases/metabolism  (1)
  • Earth Resources and Remote Sensing  (1)
  • R125
  • thermal conductivity
  • 2005-2009  (2)
  • 1
    facet.materialart.
    Unknown
    DNA demethylation in hormone-induced transcriptional derepression (2009)
    Nature Publishing Group (NPG)
    Details
    Publication Date: 2009-10-16
    Description: Epigenetic modifications at the histone level affect gene regulation in response to extracellular signals. However, regulated epigenetic modifications at the DNA level, especially active DNA demethylation, in gene activation are not well understood. Here we report that DNA methylation/demethylation is hormonally switched to control transcription of the cytochrome p450 27B1 (CYP27B1) gene. Reflecting vitamin-D-mediated transrepression of the CYP27B1 gene by the negative vitamin D response element (nVDRE), methylation of CpG sites ((5m)CpG) is induced by vitamin D in this gene promoter. Conversely, treatment with parathyroid hormone, a hormone known to activate the CYP27B1 gene, induces active demethylation of the (5m)CpG sites in this promoter. Biochemical purification of a complex associated with the nVDRE-binding protein (VDIR, also known as TCF3) identified two DNA methyltransferases, DNMT1 and DNMT3B, for methylation of CpG sites, as well as a DNA glycosylase, MBD4 (ref. 10). Protein-kinase-C-phosphorylated MBD4 by parathyroid hormone stimulation promotes incision of methylated DNA through glycosylase activity, and a base-excision repair process seems to complete DNA demethylation in the MBD4-bound promoter. Such parathyroid-hormone-induced DNA demethylation and subsequent transcriptional derepression are impaired in Mbd4(-/-) mice. Thus, the present findings suggest that methylation switching at the DNA level contributes to the hormonal control of transcription.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kim, Mi-Sun -- Kondo, Takeshi -- Takada, Ichiro -- Youn, Min-Young -- Yamamoto, Yoko -- Takahashi, Sayuri -- Matsumoto, Takahiro -- Fujiyama, Sally -- Shirode, Yuko -- Yamaoka, Ikuko -- Kitagawa, Hirochika -- Takeyama, Ken-ichi -- Shibuya, Hiroshi -- Ohtake, Fumiaki -- Kato, Shigeaki -- England -- Nature. 2009 Oct 15;461(7266):1007-12. doi: 10.1038/nature08456.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉ERATO, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchisi, Saitama 332-0012, Japan.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19829383" target="_blank"〉PubMed〈/a〉
    Keywords: 25-Hydroxyvitamin D3 1-alpha-Hydroxylase/genetics ; Animals ; Cell Line ; CpG Islands/genetics ; DNA (Cytosine-5-)-Methyltransferase/metabolism ; DNA Glycosylases/metabolism ; DNA Methylation/*drug effects ; Down-Regulation/drug effects ; Endodeoxyribonucleases/deficiency/genetics ; Mice ; Parathyroid Hormone/*pharmacology ; Phosphorylation ; Protein Kinase C/metabolism ; Response Elements/genetics ; Transcription, Genetic/*drug effects ; Vitamin D/pharmacology
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 2
    facet.materialart.
    Unknown
    Contribution of Chlorophyll Fluorescence to the Apparent Reflectance of Vegetation (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-06
    Description: Current strategies for monitoring the physiologic status of terrestrial vegetation rely on remote sensing reflectance (R) measurements, whi ch provide estimates of relative vegetation vigor based primarily on chlorophyll content. Vegetation chlorophyll fluorescence (CF) offers a non-destructive alternative and a more direct approach for diagnosis of vegetation stress before a significant reduction in chlorophyll content has occurred. Thus, monitoring of vegetation vigor based on CF may allow earlier stress detection and more accurate carbon sequestra tion estimates, than is possible using R data alone. However, the observed apparent vegetation reflectance (Ra) in reality includes contrib utions from both the reflected and fluoresced radiation. The aim of t his study is to determine the relative R and CF fractions contributing to Ra from the vegetation in the red to near-infrared region of the spectrum. The practical objectives of the study are to: 1) evaluate t he relationship between CF and R at the foliar level for corn, soybean, maple; and 2) for corn, determine if the relationship established f or healthy (optimal N) vegetation changes under N defiiency. To obtai n generally applicable results, experimental measurements were conducted on unrelated crop and tree species (maple, soybean and corn), unde r controlled conditions and a gradient of inorganic N fertilization l evels. Optical R spectra and actively induced CF emissions were obtained on the same foliar samples, in conjunction with measurements of p hotosynthetic function, pigment levels, and C and N content. The comm on spectral trends or similarities were examined. On average, 10-20% of apparent R at 685 nm was actually due to CF. The spectral trends in steady and maximum F varied significantly, with Fs (especially red) showing higher ability for species and treatment separation. The relative contribution of ChF to R varied significantly among species, with maple emitting much higher F amounts, as compared to corn and soybea n. Fs individual red and far-red bands and their ratio exhibited consistent species separations. For corn, the relative CF fraction increased in concert with the nutrient stress levels from 〈2% for non-stressed foliage to 〉7% for severely nutrient deficient plants. F685s provide d optimal treatment separation. This study confirms the trends in F68 5sE740s associated with N deficiency and vegetation stress, established usmg single narrow band excitation.
    Keywords: Earth Resources and Remote Sensing
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...