Ribosomal Protein S6, a Target of Rapamycin, Is Involved in the Regulation of rRNA Genes by Possible Epigenetic Changes in <i>Arabidopsis</i>

Kim, Yun-Kyoung,Kim, Sunghan,Shin, Yun-jeong,Hur, Yoon-Sun,Kim, Woo-Young,Lee, Myung-Sok,Cheon, Choong-Ill,Verma, Desh Pal S. American Society for Biochemistry and Molecular Bi 2014 The Journal of biological chemistry Vol.289 No.7

<P>The target of rapamycin (TOR) kinase pathway regulates various biological processes, including translation, synthesis of ribosomal proteins, and transcription of rRNA. The ribosomal protein S6 (RPS6) is one of the well known downstream components of the TOR pathway. Ribosomal proteins have been known to have diverse functions in regulating cellular metabolism as well as protein synthesis. So far, however, little is known about other possible role(s) of RPS6 in plants, besides being a component of the 40 S ribosomal subunit and acting as a target of TOR. Here, we report that RPS6 may have a novel function via interaction with histone deacetylase 2B (AtHD2B) that belongs to the plant-specific histone deacetylase HD2 family. RPS6 and AtHD2B were localized to the nucleolus. Co-expression of RPS6 and AtHD2B caused a change in the location of both RPS6 and AtHD2B to one or several nucleolar spots. ChIP analysis suggests that RPS6 directly interacts with the rRNA gene promoter. Protoplasts overexpressing both <I>AtHD2B</I> and <I>RPS6</I> exhibited down-regulation of pre-18 S rRNA synthesis with a concomitant decrease in transcription of some of the ribosomal proteins, suggesting their direct role in ribosome biogenesis and plant development. This is consistent with the mutation in <I>rps6b</I> that results in reduction in 18 S rRNA transcription and decreased root growth. We propose that the interaction between RPS6 and AtHD2B brings about a change in the chromatin structure of rDNA and thus plays an important role in linking TOR signaling to rDNA transcription and ribosome biogenesis in plants.</P>

Possible Dual Regulatory Circuits Involving AtS6K1 in the Regulation of Plant Cell Cycle and Growth

신윤정,천충일,김성한,Hui Du,최순영,Desh Pal S. Verma 한국분자세포생물학회 2012 Molecules and cells Vol.33 No.5

The role of Arabidopsis S6 Kinase 1 (AtS6K1), a down-stream target of TOR kinase, in controlling plant growth and ribosome biogenesis was characterized after generating transgenic plants expressing AtS6K1 under auxin-inducible promoter. Down-regulation of selected cell cycle regulatory genes upon auxin treatment was observed in the transgenic plants, confirming the negative regulatory role of AtS6K1 in the plant cell cycle progression reported earlier. Callus tissues established from these transgenic plants grew to larger cell masses with more number of enlarged cells than untransformed control, demonstrating functional implication of AtS6K1 in the control of plant cell size. The observed negative correlation between the expression of AtS6K1 and the cell cycle regulatory genes, however, was completely reversed in protoplasts generated from the transgenic plants expressing AtS6K1, suggesting a possible existence of dual regulatory mechanism of the plant cell cycle regulation mediated by AtS6K1. An alternative method of kinase assay, termed “substrate-mediated kinase pull down”, was employed to examine the additional phosphorylation on other domains of AtS6K1 and verified the phosphorylation of both amino- and carboxy-terminal domains, which is a novel finding regarding the phosphorylation target sites on plant S6Ks by upstream regulatory kinases. In addition, this kinase assay under the stress conditions revealed the salt- and sugar-dependencies of AtS6K1 phosphorylations.

The Importance of Arrhythmia Burden for Outcomes and Management Related to Catheter Ablation of Atrial Fibrillation

Paula Sánchez-Somonte,Enes Elvin Gul,Atul Verma 대한심장학회 2021 Korean Circulation Journal Vol.51 No.6

Atrial fibrillation (AF) ablation has been shown to be an effective treatment for AF, although our understanding of AF ablation outcomes until now, has been based on AF recurrence as a dichotomous variable. Reduction in AF burden, defined as the proportion of time that an individual is in AF during a monitoring period, has been already correlated to an improvement in quality of life and is likely a better assessment of success. Clinically, many patients may still have a few short recurrences of AF but feel much better. In addition, several studies have related higher AF burden with poorer health outcomes and a higher risk of stroke. Despite the growing understanding of AF burden, it is not clear yet which threshold of AF burden would be considered an appropriate outcome measure for AF ablation. Further investigations are needed to address that question. However, the reduction of AF burden seems to be a more accurate reflection of procedural success and a better predictor of prognosis and stroke risk than a single measure of AF.

RNA Interference-Mediated Repression of S6 Kinase 1 Impairs Root Nodule Development in Soybean

엄지현,천충일,김성한,김윤경,송석보,이석하,Desh Pal S. Verma 한국분자세포생물학회 2013 Molecules and cells Vol.35 No.3

Symbiotic nodule formation on legume roots is characterized with a series of developmental reprograming in root tissues, including extensive proliferation of cortical cells. We examined a possible involvement of the target of rapamycin (TOR) pathway, a central regulator of cell growth and proliferation in animals and yeasts, during soybean nodule development. Our results show that transcription of both GmTOR and its key downstream effector, GmS6K1, are activated during nodulation, which is paralleled with higher kinase activities of these gene products as well. RNAi-mediated knockdown of GmS6K1 impaired the nodule development with severely reduced nodule weight and numbers. In addition, expression of a few nodulins including leghemoglobin was also decreased, and consequently nitrogen fixation was found to be reduced by half. Proteomic analysis of the GmS6K1-RNAi nodules identified gluta-mine synthetase (GS), an essential enzyme for nitrogen assimilation in nodules, as one of the proteins that are significantly down regulated. These results appear to provide solid evidence for a functional link between GmS6K1 and nodule development.

Heterobeltiotic Genetic Interaction between Congenic and Syngenic Breeds of Silkworm, Bombyx mori L.

Verma A. K.,Chattopadhyay G. K.,Sengupta M.,Das S. K.,Sarkar A. K. Korean Society of Sericultural Science 2005 International Journal of Industrial Entomology Vol.11 No.2

To determine the level of heterosis, higher cocoon shell weight multivoltine congenic lines (Con. L) and bivoltine syngenic lines (Syn. L) of silkworm were used for crosses. First filial generations $(F_1s)$ expressed heterobeltiotic genetic interaction at significant magnitude (p < 0.01) for single cocoon shell weight (SCSW). The other linked characters viz., single cocoon weight (SCW) and yield by weight per 10, 000 larvae were also significantly higher (p < 0.01) than the better parental lines. All the hybrids showed significant improvement for these aforesaid characters over standard heterosis (Standard check). The reeling parameters viz., filament length, raw silk, neatness, cohesionstrokes etc, also showed improvement among the hybrids than check in congenial environment. Overall results suggested that the cross between congenic and syngenic lines provide better heterosis with good quality silk than conventional hybrids and may be used for commercial exploitation.

Direct conversion of cellulose to high-yield methyl lactate over Ga-doped Zn/H-nanozeolite Y catalysts in supercritical methanol

Verma, D.,Insyani, R.,Suh, Y. W.,Kim, S.,Kim, S.,Kim, J. unknown 2017 Green Chemistry Vol. No.

<P>For realizing sustainable bio-based refineries, it is crucial to obtain high yields of value-added chemicals via the direct conversion of cellulose and lignocellulosic biomass. Although the conversion of cellulose using homogeneous catalysts has been demonstrated to be quite successful, low cellulose conversion and poor product selectivity have been observed using heterogeneous catalysts. In this study, for the first time, the efficient conversion of cellulose to lactic acid derivatives, which can be used as a green solvent and a potential precursor for fine chemicals and biodegradable polymers, over a Ga-doped Zn/H-nanozeolite Y (Ga-doped Zn/HNZY) catalyst is described. Under optimized conditions at 280 degrees C in supercritical methanol, methyl lactate (ML) and methyl 2-methoxypropionate (MMP) are obtained in yields of 57.8% and 12.8%, respectively, from cellulose; these values are greater than those reported in previous studies conducted using heterogeneous catalysts. Using oakwood, ML and MMP are obtained in yields of 12.3% and 18.6%, respectively. A large external surface area of the HNZY support and the synergistic effect of Ga doping on ZnO enhance Lewis acid sites with the simultaneous decrease of the Bronsted acid sites. This unique catalyst (Ga-doped Zn/HNZY) is beneficial for controlling the consecutive reaction pathways of the decomposition of cellulose to glucose, retro-aldol condensation to trioses, and intramolecular Cannizzaro reaction to ML.</P>

Effect of ligand flexibility on coordination-driven self-assembly of Pt(II) metallacycles

Verma, S.,Vajpayee, V.,Lee, S.M.,Jung, H.J.,Kim, H.,Chi, K.W. Elsevier Sequoia [etc.] 2012 Inorganica chimica acta Vol.387 No.-

The effect of ligand flexibility on the self-assembly of Pt(II) metallacycles was investigated. Three diazopyridyl ligands with different flexibilities were used to synthesize three nanoscale supramolecular complexes via Pt(II) mediated self-assembly. With comparatively less flexible ligands, 4,4'azobispyridine (2) and pyridine-4-carbaldehyde azine (3), formation of [3+3] molecular triangles was observed; in contrast, the most flexible of the three ligands, pyridine-3-carbaldehyde azine (4), yielded the [2+2] molecular rhomboid. All three complexes were characterized by multinuclear NMR (<SUP>1</SUP>H and <SUP>31</SUP>P) and HR-ESI-MS, and the structure of complex 7 was further established by X-ray crystallography. These studies clearly showed that increased ligand flexibility entropically favors the formation of smaller metallacycles as the ligand can reduce angular strain through bending or conformational change.

Temporal variations of black carbon in Guangzhou, China, in summer 2006

Verma, R. L.,Sahu, L. K.,Kondo, Y.,Takegawa, N.,Han, S.,Jung, J. S.,Kim, Y. J.,Fan, S.,Sugimoto, N.,Shammaa, M. H.,Zhang, Y. H.,Zhao, Y. Copernicus GmbH 2010 Atmospheric Chemistry and Physics Vol.10 No.14

<P>Abstract. In situ measurements of the mass concentration of black carbon (BC) and mixing ratios of carbon monoxide (CO) and carbon dioxide (CO2) were made at Guangzhou, an urban measurement site in the Pearl River Delta (PRD), China, in July 2006. The average ± standard deviation (SD) concentrations of BC, CO, and CO2 were 4.7± 2.3 μgC m−3, 798± 459 ppbv, and 400± 13 ppmv, respectively. The trends of these species were mainly controlled by synoptic-scale changes in meteorology during the campaign. Based on back trajectories, data are analyzed separately for two different air mass types representing northerly and southerly flows. The northerly air masses, which constituted ~25% of the campaign, originated mostly in the PRD and hence represent observations on regional scales. On the other hand, during southerly flow (~75%), the measurements were influenced by dilution due to cleaner marine air. The diurnal patterns of BC, CO, and CO2 exhibited peak concentrations during the morning and evening hours coinciding with rush-hour traffic. The ratios of OC/BC were lower during the morning hour peaks in the concentrations of primary pollutants due to their fresh emissions mainly from vehicular traffic in Guangzhou. The diurnal variations of BC observed in southerly air masses tended to follow the traffic patterns of heavy-duty vehicles (HDV) in Guangzhou, while the roles of other sources need to be investigated. The slopes of ΔBC/ΔCO, ΔBC/ΔCO2, and ΔCO/ΔCO2 observed during northerly flows were 0.0045 μgC m−3/ppbv, 0.13 μgC m−3/ppmv, and 49.4 ppbv/ppmv, respectively, agreeing reasonably with their respective emission ratios derived from regional emission inventories. </P>

Expression of Heterotic Genetic Interaction among Multivoltine Recurrent Backcross/Congenic Lines for Higher Shell Weight of Silkworm, Bombyx mori L.

Verma, A.K.,Chattopadhyay, G.K.,Sengupta, M.,Sengupta, A.K.,Das, S.K.,Urs, S.Raje Korean Society of Sericultural Science 2003 International Journal of Industrial Entomology Vol.7 No.1

Manifestation of heterotic genetic interaction was studied in different hybrids made between multivoltine recurrent backcross (RBL)/congenic lines (Con. L) during unfavourable season when temperature and relative humidity are > $30^{\circ}C$ and 86%, respectively. A few number of silkworm race or strain or breed like Nistari (N + p or Np) can sustain the temperature above 3$0^{\circ}C$ and RH above 86%. The present heterosis study screened a hybrid i.e., CB$_{5}$Lm5RBL1.${\times}$M$_{6}$DPC-LmE$^1$RBL and its reciprocal provided heterobeltiotic effect on survival by number and pupation rate at a magnitude of 20% (p < 0.01) and yield by weight of 10% (p < 0.01). Beside all the hybrids expressed heterosis over check - Nistari (N + p) with better quality silk. Therefore, aforesaid hybrid may be useful for utilization at commercial level during adverse seasons of West Bengal.gal.

Horizontal flow fields in and around a small active region : The transition period between flux emergence and decay

Verma, M.,Denker, C.,Balthasar, H.,Kuckein, C.,Gonzá,lez Manrique, S. J.,Sobotka, M.,Bello Gonzá,lez, N.,Hoch, S.,Diercke, A.,Kummerow, P.,Berkefeld, T.,Collados, M.,Feller, A.,Hofmann, A. Springer-Verlag 2016 Astronomy and astrophysics Vol.596 No.-