Active DNA demethylation during gametogenesis regulates gene imprinting and transposon silencing in Arabidopsis

Tzung-Fu Hsieh 한국육종학회 2013 한국육종학회 심포지엄 Vol.2013 No.07

The companion cells of the Arabidopsis thaliana egg and sperm, the central and vegetative cells, undergo active DNA demethylation prior to fertilization. However, its biological significance, extent of conservation, and targeting preferences are not yet clear. We recently showed that localized demethylation of interspersed, small transposable elements is a common feature of A. thaliana companion cells. The DEMETER DNA glycosylase encodes active DNA demethylase activity and is required for seed production. DME-mediated DNA demethylation in the central cell is required to establish imprinted gene expression in the endosperm, and is considered a master regulator for plant gene imprinting. However, the similarity among DME targets in the central and vegetative cells, despite their different functions and developmental fates, suggests that establishment of genomic imprinting may not be the basal function of DME. Lack of DEMETER in vegetative cells causes reduced methylation of transposons in sperm. Our observation suggests that the primary function of companion cell demethylation is to reinforce transposon silencing in plant gametes.

Heritable Epigenetic Variation and its Potential Applications for Crop Improvement

( Changqing Zhang ),( Tzung Fu Hsieh ) 한국육종학회 2013 Plant Breeding and Biotechnology Vol.1 No.4

Phenotypic variation within organisms is driven primarily by genetic diversity. However, there is a growing appreciation that epigenetic variation, resulting from a multitude of diverse chemical modifications to the DNA and chromatin, can have profound effects on phenotype. Heritable epigenetic marks persist through meiosis and can be stably transmitted to the next generation, resulting in transgenerational epigenetic inheritance. Importantly, when epigenetic changes occur near coding genes, affecting their transcriptional state, heritable epigenetic variation can result in heritable phenotypic variation. Large-scale interrogation of epigenome inheritance in Arabidopsis has revealed that spontaneous variation in DNA methylation occurs at a rate that is orders of magnitude greater than genetic mutation, indicating the key importance of epigenetic variation during evolution. Thus, there is a potential for epigenetics to play a role in crop improvement, including regulation of trans gene expression and creation of novel epialleles. Here, we review cases of naturally occurring and genetically induced epialleles, and discuss how the studies from two epigenetic populations are rapidly increasing our understanding of epigenetic diversity.

Adjoint inversion of Chinese non-methane volatile organic compound emissions using space-based observations of formaldehyde and glyoxal

Cao, Hansen,Fu, Tzung-May,Zhang, Lin,Henze, Daven K.,Miller, Christopher Chan,Lerot, Christophe,Abad, Gonzalo Gonzá,lez,De Smedt, Isabelle,Zhang, Qiang,van Roozendael, Michel,Hendrick, Fran&cced Copernicus GmbH 2018 Atmospheric Chemistry and Physics Vol.18 No.20

<P><p><strong>Abstract.</strong> We used the GEOS-Chem model and its adjoint to quantify Chinese non-methane volatile organic compound (NMVOC) emissions for the year 2007, using the tropospheric column concentrations of formaldehyde and glyoxal observed by the Global Ozone Monitoring Experiment 2A (GOME-2A) instrument and the Ozone Monitoring Instrument (OMI) as quantitative constraints. We conducted a series of inversion experiments using different combinations of satellite observations to explore their impacts on the top-down emission estimates. Our top-down estimates for Chinese annual total NMVOC emissions were 30.7 to 49.5 (average 41.9) Tg<span class='thinspace'></span>yr<span class='inline-formula'>⁻¹</span>, including 16.4 to 23.6 (average 20.2) Tg<span class='thinspace'></span>yr<span class='inline-formula'>⁻¹</span> from anthropogenic sources, 12.2 to 22.8 (average 19.2) Tg<span class='thinspace'></span>yr<span class='inline-formula'>⁻¹</span> from biogenic sources, and 2.08 to 3.13 (average 2.48) Tg<span class='thinspace'></span>yr<span class='inline-formula'>⁻¹</span> from biomass burning. In comparison, the a priori estimate for Chinese annual total NMVOC emissions was 38.3<span class='thinspace'></span>Tg<span class='thinspace'></span>yr<span class='inline-formula'>⁻¹</span>, including 18.8<span class='thinspace'></span>Tg<span class='thinspace'></span>yr<span class='inline-formula'>⁻¹</span> from anthropogenic sources, 17.3<span class='thinspace'></span>Tg<span class='thinspace'></span>yr<span class='inline-formula'>⁻¹</span> from biogenic sources, and 2.27<span class='thinspace'></span>Tg<span class='thinspace'></span>yr<span class='inline-formula'>⁻¹</span> from biomass burning. The simultaneous use of glyoxal and formaldehyde observations helped distinguish the NMVOC species from different sources and was essential in constraining anthropogenic emissions. Our four inversion experiments consistently showed that the Chinese anthropogenic emissions of NMVOC precursors of glyoxal were larger than the a priori estimates. Our top-down estimates for Chinese annual emission of anthropogenic aromatics (benzene, toluene, and xylene) ranged from 5.5 to 7.9<span class='thinspace'></span>Tg<span class='thinspace'></span>yr<span class='inline-formula'>⁻¹</span>, 2<span class='thinspace'></span>% to 46<span class='thinspace'></span>% larger than the estimate of the a priori emission inventory (5.4<span class='thinspace'></span>Tg<span class='thinspace'></span>yr<span class='inline-formula'>⁻¹)</span>. Three out of our four inversion experiments indicated that the seasonal variation in Chinese NMVOC emissions was significantly stronger than indicated in the a priori inventory. Model simulations driven by the average of our top-down NMVOC emission estimates (which had a stronger seasonal variation than the a priori) showed that surface afternoon ozone concentrations over eastern China increased by 1-8<span class='thinspace'></span>ppb in June and decreased by 1-10<span class='thinspace'></span>ppb in December relative to the simulations using the a priori emissions and were in better agreement with measurements. We concluded that the satellite observations of formaldehyde and glyoxal together provided quantitative constraints on the emissions and source types of NMVOCs over China and improved our understanding on regional chemistry.</p> </P>

Clinical Significance of Smudge Cells in Peripheral Blood Smears in Hematological Malignancies and Other Diseases

Chang, Chih-Chun,Sun, Jen-Tang,Liou, Tse-Hsuan,Kuo, Chin-Fu,Bei, Chia-Hao,Lin, Sheng-Jun,Tsai, Wei-Ting,Tan, N-Chi,Liou, Ching-Biau,Su, Ming-Jang,Yen, Tzung-Hai,Chu, Fang-Yeh Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.4

Background: It is reported that the percentage of smudge cells in the blood smear could be a prognostic indicator in chronic lymphocytic leukemia. However, the clinical significance of smudge cells in other hematological malignancies, solid tumors or non-malignant diseases is less clear. Hence, this study was conducted to survey the clinical significance of smudge cells in hematological cancers and other disorders. Materials and Methods: From January to November, 2015, the clinical data of patients who received blood examination with differential counts for clinical purpose and were found to have smudge cells in the peripheral blood film in Far Eastern Memorial Hospital were selected. The percentage of smudge cells and patient outcomes were evaluated for further univariate and survival analyses. Results: A total of 102 patients with smudge cells in their blood smears were included. Smudge cells were frequently presented in out-of-hospital cardiac arrest (OHCA; n=30), infections (n=23), hematological cancers (n=23) and solid cancers (n=10). There was no relationship between the percentage of smudge cells and the patient mortality in all diseases (OR: 1.08, 95% CI: 0.47-2.48, P=1.000) as well as the OHCA group (OR: 1.91, 95% CI: 0.38-9.60, P=0.694). It was observed that in patients with all cancers with the percentage of smudge cells less than 50% had a lower mortality rate in comparison with those who had the percentage of smudge cells of 50% or more (OR: 22.29, 95% CI: 2.38-208.80, P<0.001). Additionally, it was seemingly that patients with smudge cells of 50% or more had a lower survival rate than those with smudge cells less than 50% in all cancers with follow-up at 2-month intervals, but without statistical significance (P=0.064). Conclusions: Our survey indicated that in all cancers, those who had higher percentage of smudge cells were prone to have poor outcomes when compared with the subjects with lower percentage of smudge cells. This finding was quite different from the results of previous studies in which the race-ethnicity of most study populations was non-Asian; hence, further investigations are required. Besides, there was no apparent association of the percentage of smudge cells with patient outcomes in all diseases, including OHCA.