Biology subjects

Wan, W.

Publications and source records attributed to Wan, W..

22 records · Page 2Linked to original sources

bioRxiv2020

Ebola and Marburg virus matrix layers are locally ordered assemblies of VP40 dimers

A key step in the life cycle of enveloped viruses is the budding of nascent virions from the host membrane. In filoviruses such as Ebola and Marburg virus, this process is achieved by the matrix protein VP40. When expressed alone, VP40 induces the budding of filamentous virus-like particles, suggesting that localization to the plasma membrane, oligomerization into a matrix layer, and the generation of membrane curvature are intrinsic properties of VP40. While a number of crystal structures of VP40 have been determined in various oligomerization states, there has been no direct information on the structure of assembled VP40 matrix layers within viruses or virus-like particles. Here, we present structures of Ebola and Marburg VP40 matrix layers in intact virus-like particles, as well as within intact Marburg viruses. We find that the matrix layers are formed from VP40 dimers which assemble into extended chains via C-terminal domain interactions. These chains stack into layers, forming a 2D lattice below the membrane surface. However, these 2D lattices are only locally ordered, forming a patchwork assembly across the membrane surfaces and suggesting that assembly may begin at multiple points. These observations define the structure and arrangement of the matrix protein layer that mediates the formation of filamentous filovirus particles.

microbiology↗

bioRxiv2019

Development of a multiparent advanced generation intercross (MAGIC) population for genetic exploitation of complex traits in Brassica juncea: glucosinolate content as an example

Multiparent advanced generation intercross (MAGIC) populations have recently been developed to allow the high-resolution mapping of complex quantitative traits. This article describes the development of one MAGIC population and verifies its potential application for mapping quantitative trait loci (QTLs) in B. juncea. The population was developed from eight founders with diverse traits and composed of 408 F6 recombinant inbred lines (RILs). To develop one rapid and simplified way for using the MAGIC population, a subset of 133 RILs as the primary mapping population were genotyped using 346 intron-length polymorphism (ILP) polymorphic markers. The population lacks significant signatures of population structure that are suitable for the analysis of complex traits. Genome-wide association mapping (GWAS) identified three major glucosinolate (GSL) QTLs of QGsl.ig01.1 on J01 for indole GSL (IG), QGsl.atg09.1 on J09 and QGsl.atg11.1 on J11 for aliphatic GSL (AG) and total GSL (TG). The candidate genes for QGsl.ig01.1, QGsl.atg09.1 and QGsl.atg11.1 are GSH1, GSL-ALK and MYB28, which are involved in converting glutamate and cysteine to{gamma} -EC, the accumulation of glucoraphanin, and the whole process of AG metabolism, respectively. One effective method for association mapping of quantitative traits in the B. juncea MAGIC population is also suggested by utilization of the remaining 275 RILs and incorporation of the novel kompetitive allele specific PCR (KASP) technique. In addition to its QTL mapping purpose, the MAGIC population could also be potentially utilized in variety development by breeders.

genetics↗

bioRxiv2019

Exploring the basis of 2-propenyl and 3-butenyl glucosinolate synthesis by QTL mapping and RNA-sequencing in Brassica juncea

Brassica juncea is used as a condiment, as vegetables and as an oilseed crop, especially in semiarid areas. In the present study, we constructed a genetic map using one recombinant inbred line (RIL) of B. juncea. A total of 304 ILP (intron length polymorphism) markers were mapped to 18 linkage groups designated LG01-LG18 in B. juncea. The constructed map covered a total genetic length of 1671.13 cM with an average marker interval of 5.50 cM. The QTLs for 2-propenyl glucosinolates (GSLs) colocalized with the QTLs for 3-butenyl GSLs between At1g26180 and BnapPIP1580 on LG08 in the field experiments of 2016 and 2017. These QTLs accounted for an average of 42.3% and 42.6% phenotypic variation for 2-propenyl and 3-butenyl GSLs, respectively. Furthermore, the Illumina RNA-sequencing technique was used to excavate the genes responsible for the synthesis of GSLs in the siliques of the parental lines of the RIL mapping population, because the bulk of the seed GSLs might originate from the siliques. Comparative analysis and annotation by gene ontology (GO) and kyoto encyclopedia of genes and genomes (KEGG) revealed that 324 genes were involved in GSL metabolism, among which only 24 transcripts were differentially expressed genes (DEGs). Among those DEGs, 15 genes were involved in the biosynthesis and transport of aliphatic GSLs, and their expression patterns were further validated by qRT-PCR analysis. These RNA-Seq results will be helpful for further fine mapping, gene cloning and genetic mechanisms of 2-propenyl and 3-butenyl GSLs in B. juncea.

molecular biology↗

bioRxiv2019

Cardiac myocytes respond differentially and synergistically to matrix stiffness and topography

During cardiac disease progression, myocytes undergo molecular, functional and structural changes, including increases in cell size and shape, decreased myocyte alignment and contractility. The heart often increases extracellular matrix production and stiffness, which affect myocytes. The order and hierarchy of these events remain unclear as available in vitro cell culture systems do not adequately model both physiologic and pathologic environments. Traditional cell culture substrates are 5-6 orders of magnitude stiffer than even diseased native cardiac tissue. Studies that do account for substrate stiffness often do not consider intercellular alignment and vice versa. We developed a cardiac myocyte culture platform that better recapitulates native tissue stiffness while simultaneously introducing topographical cues that promote cellular alignment. We show that stiffness and topography impact myocyte molecular and functional properties. We used a spatiotemporally-tunable, photolabile hydrogel platform to generate a range of stiffness and micron-scale topographical patterns to guide neonatal rat ventricular myocyte morphology. Importantly, these substrate patterns were of subcellular dimensions to test whether cells would spontaneously respond to topographical cues rather than an imposed geometry. Cellular contractility was highest and the gene expression profile was most physiologic on gels with healthy cardiac tissue stiffness. Surprisingly, while elongated patterns in stiff gels yielded the greatest cellular alignment, the cells actually had more pathologic functional and molecular profiles. These results highlight that morphological measurements alone are not a surrogate for overall cellular health as many studies assume. In general, substrate stiffness and micropatterning synergistically affect cardiac myocyte phenotype to recreate physiologic and pathologic microenvironments.\n\nSignificance StatementHeart disease is accompanied by organ- and cellular-level remodeling, and deconvoluting their interplay is complex. Cellular-level change is best studied in vitro due to greater control and uniformity of cell types compared to animals. One common metric is degree of cellular alignment as misalignment of myocytes is a hallmark of disease. However, most studies utilize featureless culture surfaces that are orders of magnitude stiffer than, and do not mimic the scaffolding of, the heart. We developed a hydrogel platform with tunable stiffness and patterns providing topographical alignment cues. We cultured heart cells on and characterized multifactorial responses to these dynamic surfaces. Interestingly, conditions that yielded greatest alignment did not yield the healthiest functional and molecular state. Thus, morphology alone is not an indicator of overall cellular health.

cell biology↗