Wu, H.-L. | Search bioRxiv

bioRxiv2020

Identifications of novel avian and mammalian deltaviruses filled the large evolutionally gaps and revealed inter-family transmission of deltaviruses

Hepatitis delta virus (HDV) is a satellite virus that requires hepadnavirus envelope proteins for its transmission. Although recent studies identified HDV-related deltaviruses in certain animals, the evolution of deltaviruses, such as the origin of HDV and the mechanism of its coevolution with its helper viruses, is unknown, mainly because of the phylogenetic gaps among deltaviruses. Here we identified novel deltaviruses of passerine birds, woodchucks, and white-tailed deer by extensive database searches and molecular surveillance. Phylogenetic and molecular epidemiological analyses suggest that HDV originated from mammalian deltaviruses and the past interspecies transmission of mammalian and passerine deltaviruses. Further, metaviromic and experimental analyses suggest that the satellite-helper relationship between HDV and hepadnavirus was established after the divergence of the HDV lineage from non-HDV mammalian deltaviruses. Our findings enhance our understanding of deltavirus evolution, diversity, and transmission, indicating the importance of further surveillance for deltaviruses.

microbiology↗

bioRxiv2019

Developmental Characterization of Zswim5 Expression in the Progenitor Domains and Tangential Migration Pathways of Cortical Interneurons in the Mouse Forebrain

GABAergic interneurons play an essential role in modulating cortical networks. The progenitor domains of cortical interneurons are localized in developing ventral forebrain, including the medial ganglionic eminence (MGE), caudal ganglionic eminence (CGE), preoptic area (POA) and preoptic hypothalamic border domain (POH). Here, we characterized the expression pattern of Zswim5, an MGE-enriched gene in the mouse forebrain. At E11.5 to E13.5, prominent Zswim5 expression was detected in the subventricular zone (SVZ) of MGE, CGE, POA and POH of ventral telencephalon in which progenitors of cortical interneurons resided. At E15.5 and E17.5, Zswim5 remained detectable in the SVZ of pallidal primordium (MGE). Zswim5 mRNA was markedly decreased after birth and was absent in the adult forebrain. Interestingly, Zswim5 expression pattern resembled the tangential migration pathways of cortical interneurons. Zswim5-positive cells in the MGE appeared to migrate from the MGE through the SVZ of LGE to overlying neocortex. Indeed, Zswim5 was co-localized with Nkx2.1 and Lhx6, markers of progenitos and migratory cortical interneurons. Double labeling showed that Mash1/Ascl1-positive cells did not express Zswim5. Zswim5 expressing cells showed none or at most low levels of Ki67 but co-expressed Tuj1 in the SVZ of MGE. These results suggest that Zswim5 is immediately upregulated as progenitors exiting cell cycle to become postmitotic. Given that recent studies have elucidated that the cell fate of cortical interneurons is determined shortly after postmitotic, the timing of Zswim5 expression in early postmitotic cortical interneurons suggests a potential role of Zswim5 in regulation of neurogenesis and tangential migration of cortical interneurons.

neuroscience↗