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1. chinaXiv:202004.00019 [pdf]

The phylogenetic position of Cladiucha within Tenthredinidae based on comprehensive mitochondrial phylogenomics and the evidence from comparative analyses of rRNA secondary structure

Niu, Gengyun; Jiang Sijia; Do?an, ?zgül ; Korkmaz, Ertan Mahir; Budak, Mahir ; Wu, Duo; Wei, Meicai
Subjects: Biology >> Entomology

Two mitogenomes of Cladiucha were newly reported and shown typical pattern of gene arrangement. The phylogenetic position of Cladiucha was obtained from tree reconstruction using various data treatment methods and substitution models. Significant heterogeneity in the nucleotide composition and mutational biases was found in the mitochondrial protein-coding genes, and the third codon position exhibited high levels of saturation. Therefore, 14 datasets were conducted under both site-homogeneous and site-heterogeneous models. The following conclusions were drawn from the phylogenetic analyses: (i) the monophyly of Tenthredinidae was confirmed, (ii) the monophyly of Allantinae + Tenthredininae + Megabelesinae was approved, and (iii) within the family, ((((Tenthredininae + Fenusinae) + Allantinae) + Megabelesinae) + Nematinae) is probably the most acceptable cladogram for the phylogeny of Tenthredinidae, which is also supported by the morphological analysis and a comparative study on the rRNA secondary structure. Divergence time estimation analyses indicated that diversification of the major superfamilies of the suborder Symphyta occurred around 232.9 Ma, and the splits of Tenthredinidae were dated to 146 Ma, which corresponding to the origin of the earliest lineages of flowering plants and major diversifications of core angiosperms, respectively. The Cladiucha arose in the Mid-Miocene; at that time, magnoliids are rapidly undergoing genus-species differentiation. "

submitted time 2020-04-19 Hits10637Downloads951 Comment 0

2. chinaXiv:202002.00081 [pdf]

SARS-coronavirus-2 nsp13 possesses NTPase and RNA helicase activities

Shu, Ting; Huang, Muhan; Wu, Di; Ren, Yujie; Zhang, Xueyi; Han, Yang; Mu, Jingfang; Wang, Ruibing; Qiu, Yang; Zhang, Ding-Yu; Zhou, Xi
Subjects: Biology >> Virology

The ongoing outbreak of Coronavirus Disease 2019 (COVID-19) has become a global pandemic and crisis. SARS-coronavirus-2 (SARS-CoV-2), the causative pathogen of COVID-19, is a positive-sense single-stranded RNA virus belonging to the family Coronaviridae. For RNA viruses, virus-encoded RNA helicases have long been recognized to play pivotal roles during viral life cycles by facilitating the correct folding and replication of viral RNAs. Here, our studies show that SARS-CoV-2-encoded nonstructural protein 13 (nsp13) possesses the nucleoside triphosphate hydrolase (NTPase) and RNA helicase activities that can hydrolyze all types of NTPs and unwind RNA helices dependently of the presence of NTP, and further characterize the biochemical characteristics of these two enzymatic activities associated with SARS-CoV-2 nsp13. Moreover, we found that some bismuth salts could effectively inhibit both the NTPase and RNA helicase activities of SARS-CoV-2 nsp13 in a dose-dependent manner. Thus, our findings demonstrate the NTPase and helicase activities of SARS-CoV-2 nsp13, which may play an important role in SARS-CoV-2 replication and serve as a target for antivirals.

submitted time 2020-04-19 Hits16045Downloads1751 Comment 0

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