Biology subjects

Zhao, D.

Publications and source records attributed to Zhao, D..

6 recordsLinked to original sources

bioRxiv2018

Microbial and Metabolic Succession on Common Building Materials Under High Humidity Conditions

Despite considerable efforts to characterize the ecology of bacteria and fungi in the built environment (BE), the metabolic mechanisms underpinning their colonization and successional dynamics remain unclear. Here, we applied bacterial/viral particle counting, qPCR, 16S and ITS rRNA amplicon sequencing, and metabolomics to longitudinally characterize the ecological dynamics of four commonly used building materials maintained at high humidity conditions (~94% RH). We varied the natural inoculum provided to each material by placing them in different occupied spaces, and we wet the surface of half of the samples of each material to simulate a flooding event. As expected, different materials showed different bacterial and viral particle abundance, with wet materials having higher growth rates and lower alpha diversity compared to non-wetted materials. Wetting described the majority of the variance in bacterial, fungal and metabolite structure, and material type only influenced bacterial and metabolic diversity, while location of inoculation was only weakly associated with bacterial and fungal beta diversity. Metabolites indicative of microbial activity were identified, as were those that were native to the surface material. Glucose-phosphate was abundant on all materials (except mold-free gypsum) and was correlated with Enterobacteriaceae, which could indicate a potential bacterial nutrient source. A compound consistent with scopoletin, a plant metabolite with antimicrobial activity, was significantly negatively correlated with Bacillus and positively correlated with Pseudomonas and enriched in medium density fiberboard (MDF) materials. In wet samples, the alkaloids nigragillin and fumigaclavine C, both with antimicrobial properties, were significantly positively correlated with the fungal phylum Ascomycota. Nigragillin, was also negatively correlated with Bacillus and Pseudomonas abundance. Thiabendazole and azoxystrobin (anti-fungal compounds) were highly abundant on mold-resistant gypsum wallboard and likely directly influenced the decreased fungal growth observed on this material. The mold-resistant gypsum material also showed a significant increase in bacterial alpha diversity, and bacterial and viral particle abundance, as well as a decrease in metabolite diversity, likely a result of reduced fungal growth. Penicillium taxa were positively correlated with thiabendazole, which suggested the persistence of resistant strains. Also, specific to the wet samples, Bacillus abundance was positively correlated with the azoxystrobin, suggesting bi-directional competitive adaptation, and positively correlated with metabolites known to interfere with Pseudomonas biofilm formation, which could explain the anti-correlation between these taxa. As expected, high moisture conditions enabled faster growth of inoculating microorganisms, whose composition, chemistry, and competition was shaped by surface material, suggesting that both fungal and bacterial growth need to be considered when determining the impact of dampness in built environments.

microbiology↗

bioRxiv2018

PKD2 influence uric acid levels and gout risk by interacting with ABCG2

BackgroundUric acid is the final product of purine metabolism and elevated serum urate levels can cause gout. Conflicting results were reported for the effect of PKD2 on serum urate levels and gout risk. Therefore, our study attempted to state the important role of PKD2 in influencing the pathogenesis of gout.\n\nMethodSNPs in PKD2 (rs2725215 and rs2728121) and ABCG2 (rs2231137 and rs1481012) were tested in approximately 5,000 Chinese individuals.\n\nResultsTwo epistatic interactions between loci in PKD2 (rs2728121) and ABCG2 (rs1481012 and rs2231137) showed distinct contributions to uric acid levels with P int values of 0.018 and 0.004, respectively, and the associations varies by gender and BMI. The SNP pair of rs2728121 and rs1481012 justly played roles in uric acid in females (P int = 0.006), while the other pair did in males (P int = 0.017). Regarding BMI, the former SNP pair merely contributed in overweigh subjects (P int = 0.022) and the latter one did in both normal and overweigh individuals (P int = 0.013 and 0.047, respectively). Furthermore, the latter SNP pair was also associated with gout pathology (P int = 0.001), especially in males (P int = 0.001). Finally, functional analysis showed potential epistatic interactions in those genes region and PKD2 mRNA expression had a positive correlation with ABCG2s (r = 0.743, P = 5.83e-06).\n\nConclusionOur study for the first time identified that epistatic interactions between PKD2 and ABCG2 influenced serum urate concentrations and gout risk, and PKD2 might affect the pathogenesis from elevated serum urate to hyperuricemia to gout by modifying ABCG2.

genetics↗

bioRxiv2018

SMARTcleaner: identify and clean off-target signals in SMART ChIP-seq analysis

BackgroundNoises and artifacts may arise in several steps of the next-generation sequencing (NGS) process. Recently, a NGS library preparation method called SMART, or Switching Mechanism At the 5 end of the RNA Transcript, is introduced to prepare ChIP-seq (chromatin immunoprecipitation and deep sequencing) libraries from small amount of DNA material. The protocol adds Ts to the 3 end of DNA templates, which is subsequently recognized and used by SMART poly(dA) primers for reverse transcription and then addition of PCR primers and sequencing adapters. The poly(dA) primers, however, can anneal to poly(T) sequences in a genome and amplify DNA fragments that are not enriched in the immunoprecipitated DNA templates. This off-target amplification results in false signals in the ChIP-seq data.\n\nResultsHere, we show that the off-target ChIP-seq reads derived from false amplification of poly(T/A) genomic sequences have unique and strand-specific features. Accordingly, we develop a tool (called \"SMARTcleaner\") that can exploit the features to remove SMART ChIP-seq artifacts. Application of SMARTcleaner to several SMART ChIP-seq datasets demonstrates that it can remove reads from off-target amplification effectively, leading to improved ChIP-seq peaks and results.\n\nConclusionsSMARTcleaner could identify and clean the false signals in SMART-based ChIP-seq libraries, leading to improvement in peak calling, and downstream data analysis and interpretation.

bioinformatics↗

bioRxiv2017

High-throughput fitness profiling of Zika virus E protein reveals different roles for N-linked glycosylation during infection of mammalian and mosquito cells

Zika virus (ZIKV) infection causes Guillain-Barre syndrome and severe birth defects. ZIKV envelope (E) protein is the major viral protein involved in cell receptor binding and entry and therefore considered one of the major determinants in ZIKV pathogenesis. Here, we report a gene-wide mapping of functional residues of ZIKV E protein using a mutant library with changes covering every nucleotide position. By comparing the replication fitness of every viral mutant between mosquito and human cells, we identified that mutations affecting N-linked glycosylation at N154 position display the most divergence. Through characterizing individual mutants, we show that, while ablation of N-linked glycosylation selectively benefits ZIKV infection of mosquito cells by enhancing cell entry, it either had little impact on ZIKV infection on certain human cells or decreased infection through entry factor DC-SIGN. In conclusion, we define the roles of individual residues of ZIKV envelope protein, which contribute to ZIKV replication fitness in human and mosquito cells.\n\nHighlightsO_LIGene-wide mapping of functional residues of E protein in human and mosquito cells.\nC_LIO_LIMutations affecting N-linked glycosylation display the most dramatic difference.\nC_LIO_LIN-linked glycosylation decreases ZIKV entry into mosquito cells.\nC_LIO_LIN-linked glycosylation is important for DC-SIGN mediated infection of human cells.\nC_LI

microbiology↗

bioRxiv2017

Identification of Iridoid Synthases from Nepeta species: Iridoid cyclization does not determine nepetalactone stereochemistry

Graphical Abstract\n\nO_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=105 SRC=\"FIGDIR/small/179572_ufig1.gif\" ALT=\"Figure 1\">\nView larger version (91K):\norg.highwire.dtl.DTLVardef@cc600dorg.highwire.dtl.DTLVardef@1b6240dorg.highwire.dtl.DTLVardef@f8e1beorg.highwire.dtl.DTLVardef@1acb9dd_HPS_FORMAT_FIGEXP M_FIG Iridoid synthase from Nepeta cateria (catnip) and Nepeta mussinii, have been cloned and characterized.\n\nC_FIG AbstractNepetalactones are iridoid monoterpenes with a broad range of biological activities produced by plants in the Nepeta genus. However, none of the genes for nepetalactone biosynthesis have been discovered. Here we report the transcriptomes of two Nepeta species, each with distinctive profiles of nepetalactone stereoisomers. As a starting point for investigation of nepetalactone biosynthesis in Nepeta, these transcriptomes were used to identify candidate genes for iridoid synthase homologs, an enzyme that has been shown to form the core iridoid skeleton in several iridoid producing plant species. Iridoid synthase homologs identified from the transcriptomes were cloned, heterologously expressed, and then assayed with the 8-oxogeranial substrate. These experiments revealed that catalytically active iridoid synthase enzymes are present in Nepeta, though there are unusual mutations in key active site residues. Nevertheless, these enzymes exhibit similar catalytic activity and product profile compared to previously reported iridoid synthases from other plants. Notably, four nepetalactone stereoisomers with differing stereochemistry at the 4 and 7 positions - which are generated during the iridoid synthase reaction - are observed at different ratios in various Nepeta species. This work strongly suggests that the variable stereochemistry at these 4 and 7 positions of nepetalactone diastereomers is established further downstream in the iridoid pathway in Nepeta. Overall, this work provides a gateway into the biosynthesis of nepetalactones in Nepeta.\n\nHighlightsO_LISpecies within the Nepeta genus (such as catnip) produce nepetalactone iridoids\nC_LIO_LIThe enzymes that produce the iridoid scaffold of nepetalactone were identified from two species of Nepeta\nC_LIO_LIThe iridoid synthase enzymes are not responsible for the stereochemical variation in these iridoids\nC_LI

biochemistry↗

bioRxiv2017

Enriched expression of genes associated with autism spectrum disorders in human inhibitory neurons

Autism spectrum disorder (ASD) is highly heritable but genetically heterogeneous. The affected neural circuits and cell types remain unclear and may vary at different developmental stages. By analyzing multiple sets of human single cell transcriptome profiles, we found that ASD candidates showed enriched gene expression in neurons, especially in inhibitory neurons. ASD candidates were also more likely to be the hubs of the co-expressed module that is highly expressed in inhibitory neurons, a feature not detected for excitatory neurons. In addition, we found that upregulated genes in multiple ASD cortex samples were also enriched with genes highly expressed in inhibitory neurons, suggesting a potential increase of inhibitory neurons and an imbalance in the ratio between excitatory and inhibitory neurons. Furthermore, the downstream targets of several ASD candidates, such as CHD8, EHMT1 and SATB2, also displayed enriched expression in inhibitory neurons. Taken together, our analysis of single cell transcriptomic data suggest that inhibitory neurons may be the major neuron subtype affected by the disruption of ASD gene networks, providing single cell functional evidence to support the excitatory/inhibitory (E/I) imbalance hypothesis.

genetics↗