COVID-19, which is caused by a novel coronavirus known as SARS-CoV-2, has spread rapidly around the world, and it has infected more than 29 million individuals as recorded on 16 September 2020. Much effort has been made to stop the virus from spreading, and there are currently no approved pharmaceutical products to treat COVID-19. Here, we apply an in silico approach to investigate more than 3800 FDA approved drugs on the viral RBD S 1 -ACE2 interface as a target. The compounds were investigated through flexible ligand docking, ADME property calculations and protein–ligand interaction maps. Molecular dynamics (MD) simulations were also performed on eleven compounds to study the stability and the interactions of the protein–ligand complexes. The MD simulations show that bagrosin, chidamide, ebastine, indacaterol, regorafenib, salazosulfadimidine, silodosin and tasosartan are relatively stable near the C terminal domain (CTD1) of the S 1 subunit of the viral S protein. The relative MMGBSA binding energies show that silodosin has the best binding to the target. The constant velocity steered molecular dynamics (SMD) simulations show that silodosin preferentially interacts with the RBD S 1 and has potential to act as an interfering compound between viral spike–host ACE2 interactions. Communicated by Ramaswamy H. Sarma

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Rice adventitious/crown roots developing from non-root tissues shape up the root architecture.Mechanisms underlying initiation and subsequent outgrowth of CR primordia (CRP) remain under explored. Here, we provide genome-wide dynamics of gene expression patterns and stage-specific transcriptional signatures at distinct developmental stages of CRP formation. Our analyses reveal that early regulated transcription of potential epigenetic modifiers, transcription factors and cell division regulators prime the initiation of CRP followed by progressive activation of auxin signaling modules ensure their outgrowth. In depth analysis of spatio-temporal expression patterns of key cell fate determinants and functional analyses of rice WUSCHEL RELATED HOMEOBOX10 (OsWOX10) and PLETHORA (OsPLT) genes reveal their unprecedented role in CRP development. Our study suggests that OsWOX10 activates OsERF3 and OsCRL1 expression during CRP initiation and OsPLTs expression to accomplish their outgrowth. Interestingly, OsPLT genes, when expressed in the transcriptional domain of root-borne lateral root primordia of Arabidopsis plt mutant, rescued their outgrowth demonstrating the conserved role of PLT genes in root primordia outgrowth irrespective of their developmental origin. Together, these findings unveil the molecular framework of cellular reprogramming during trans-differentiation of shoot tissue to root leading to culmination of robust root architecture in monocot species which got evolutionary diverged from dicots. T.G. performed experiments of LCM, RNA in situ hybridization and OsWOX10 function in rice. Z.S. performed experiments for auxin responses and functions of OsPLT1 and OsPLT4 in rice. A.K.D., R.S.S and M.J. performed RNA sequencing data analysis. M.Y. with T.G. contributed for function of OsWOX10 in Arabidopsis. V.V. studied function of rice PLTs in Arabidopsis. D.C. contributed in LCM experiments. M.J., K.P. and S.R.Y. designed experiments, analyzed data and Academy of Sciences, Shanghai, China is acknowledged for kindly providing Arabidopsis wox11-2, wox12-1 and wox11-2 wox12-1 seeds. Ashish Kumar and Sonia Choudhary are acknowledged for their support in growing plants.

The recent rapid explosion of web based applications and information system have further increased the risk exposure of databases and thus, data protection is today more crucial than ever. It is more important to protect data not only from external intruders but also internal intruders. In this paper, different access control mechanisms and its models discussed to achieving the confidentiality, integrity and availability goals of the database security in the organization. The models are useful in classification systems to prevent theft of information and effect of data at higher classification levels.

A .S . Y A DA V, R .K . V A SH IS H AT , L . D. KU Y KE ND A LL AN D F. M. H AS HE M . 1998. A perturbation of the histidine biosynthetic pathway in legume microsymbionts can abolish their symbiotic competence. Twenty-one histidine-requiring (His − ) mutants were isolated from berseem clover-nodulating, symbiotically-competent (Nod + , Fix + ) Rhizobium leguminosarum bv. 'trifolii' strain RTH 48 Sm r by N-methyl-N?-nitro-Nnitrosoguanidine (MNNG) mutagenesis followed by enrichment. These mutants were analysed for their biochemical defect and the corresponding effect, if any, on their symbiotic abilities. Cross-feeding, supplementation and enzymatic studies identified three types of mutants. Group 1 mutants, His-2 and His-12, grew with histidine supplementation but not with the addition of either L-histidinol or L-histidinol phosphate to the medium ; they lacked histidinol dehydrogenase (EC 1.1.1.23) activity and consequently formed only ineffective, or 'non-fixing' nodules. Group 2 mutant, His-17, grew when supplemented with either L-histidinol or L-histidine, had low histidinol phosphate phosphatase (EC 3.1.3.15) activity (37% of wild-type), and consequently failed to nodulate berseem clover. Group 3, the remaining 18 mutants, grew when supplemented with L-histidinol phosphate, L-histidinol or histidine, and did not nodulate. Typically, reversion rates were between 10 −7 and 10 −8 . Defects in early steps of the pathway abolished nodulating ability, whereas lesions in the last step did not. The last step, however, was required for symbiotic nitrogen fixation. It is hypothesized that histidine may be supplied by the host in sufficient quantity for nodulation by histidinol dehydrogenase mutants to occur, whereas the amount provided in the nodule may be insufficient to support bacteroid development and nitrogen fixation.