Biology subjects

Fang, C.

Publications and source records attributed to Fang, C..

88 records · Page 5Linked to original sources

bioRxiv2020

Efficient and stable metabarcoding sequencing from DNBSEQ-G400 sequencer examined by large fungal community analysis

ABSTRACTMetabarcoding has become the de facto method for characterizing the structure of microbial communities in complex environmental samples. To determine how sequencing platform may influence microbial community characterization, we present a large-scale comparison of two sequencing platforms; Illumina MiSeq and a new platform DNBSEQ-G400 developed by MGI Tech. The accuracy of DNBSEQ-G400 on bacterial and fungal mock samples and compared sequencing consistency and precision between DNBSEQ-G400 and MiSeq platforms by sequencing the fungal ITS2 region from 1144 soil samples with 3 technical replicates. The DNBSEQ-G400 showed a high accuracy in reproducing mock communities containing different proportions of bacteria and fungi, respectively. The taxonomic profiles of the 1144 soil samples generated by the two DNBSEQ-G400 modes closely resembled each other and were highly correlated with those generated by the MiSeq platform. Analyses of technical replicates demonstrated a run bias against certain taxa on the MiSeq but not DNBSEQ-G400 platform. Based on lower cost, greater capacity, and less bias, we conclude that DNBSEQ-G400 is an optimal platform for short-term metabarcoding of microbial communities.IMPORTANCE Experimental steps that generate sequencing bias during amplicon sequencing have been intensively evaluated, including the choice of primer pair, polymerase, PCR cycle and technical replication. However, few studies have assessed the accuracy and precision of different sequencing platforms. Here, we compared the performance of newly released DNBSEQ-G400 sequencer with that of the commonly used Illumina MiSeq platform by leveraging amplicon sequencing of a large number of soil samples. Significant sequencing bias among major fungal genera was found in parallel MiSeq runs, which can be easily neglected without the use of sequencing controls. We emphasize the importance of technical controls in large-scale sequencing efforts and provide DNBSEQ-G400 as an alternative with increased sequencing capacity and more stable reproducibility for amplicon sequencing.View Full Text

microbiology↗

bioRxiv2020

Bi-channel Image Registration and Deep-learning Segmentation (BIRDS) for efficient, versatile 3D mapping of mouse brain

We have developed an open-source software called BIRDS (bi-channel image registration and deep-learning segmentation) for the mapping and analysis of 3D microscopy data of mouse brain. BIRDS features a graphical user interface that is used to submit jobs, monitor their progress, and display results. It implements a full pipeline including image pre-processing, bi-channel registration, automatic annotation, creation of 3D digital frame, high-resolution visualization, and expandable quantitative analysis (via link with Imaris). The new bi-channel registration algorithm is adaptive to various types of whole brain data from different microscopy platforms and shows obviously improved registration accuracy. Also, the attraction of combing registration with neural network lies in that the registration procedure can readily provide training data for network, while the network can efficiently segment incomplete/defective brain data that are otherwise difficult for registration. Our software is thus optimized to enable either minute-timescale registration-based segmentation of cross-modality whole-brain datasets, or real-time inference-based image segmentation for various brain region of interests. Jobs can be easily implemented on Fiji plugin that can be adapted for most computing environments.

neuroscience↗

bioRxiv2020

Network-enabled efficient image restoration for 3D microscopy of turbid biological specimens

Though three-dimensional (3D) fluorescence microscopy has been an essential tool for modern life science research, the light scattering by biological specimens fundamentally prevents its more widespread applications in live imaging. We hereby report a deep-learning approach, termed ScatNet, that enables reversion of 3D fluorescence microscopy from high-resolution targets to low-quality, light-scattered measurements, thereby allowing restoration for a single blurred and light-scattered 3D image of deep tissue, with achieving improved resolution and signal-to-noise ratio. Our approach can computationally extend the imaging depth for current 3D fluorescence microscopes, without the addition of complicated optics. Combining ScatNet approach with cutting-edge light-sheet fluorescence microscopy, we demonstrate that the image restoration of cell nuclei in the deep layer of live Drosophila melanogaster embryos at single-cell resolution. Applying our approach to two-photon excitation microscopy, we could improve the signal and resolution of neurons in mouse brain beyond the photon ballistic region.

bioengineering↗

bioRxiv2020

Systematic Chromatin Architecture Analysis in Xenopus tropicalis Reveals Conserved Three-Dimensional Folding Principles of Vertebrate Genomes

Metazoan genomes are folded into 3D structures in interphase nuclei. However, the molecular mechanism remains unknown. Here, we show that topologically associating domains (TADs) form in two waves during Xenopus tropicalis embryogenesis, first at zygotic genome activation and then as the expression of CTCF and Rad21 is elevated. We also found TAD structures continually change for at least three times during development. Surprisingly, the directionality index is preferentially stronger on one side of TADs where orientation-biased CTCF and Rad21 binding are observed, a conserved pattern that is found in human cells as well. Depletion analysis revealed CTCF, Rad21, and RPB1, a component of RNAPII, are required for the establishment of TADs. Overall, our work shows that Xenopus is a powerful model for chromosome architecture analysis. Furthermore, our findings indicate that cohesin-mediated extrusion may anchor at orientation-biased CTCF binding sites, supporting a CTCF-anchored extrusion model as the mechanism for TAD establishment.

genetics↗

bioRxiv2020

Cancer-specific CTCF binding facilitates oncogenic transcriptional dysregulation

BackgroundThe three-dimensional genome organization is critical for gene regulation and can malfunction in diseases like cancer. As a key regulator of genome organization, CCCTC-binding factor (CTCF) has been characterized as a DNA-binding protein with important functions in maintaining the topological structure of chromatin and inducing DNA looping. Among the prolific binding sites in the genome, several events with altered CTCF occupancy have been reported as associated with effects in physiology or disease. However, there is no hitherto a comprehensive survey of genome-wide CTCF binding patterns across different human cancers. ResultsTo dissect functions of CTCF binding, we systematically analyze over 700 CTCF ChIP-seq profiles across human tissues and cancers and identify cancer-specific CTCF binding patterns in six cancer types. We show that cancer-specific lost and gained CTCF binding events are associated with altered chromatin interactions in patient samples, but not always with DNA methylation changes or sequence mutations. While lost bindings primarily occur near gene promoters, most gained CTCF binding events are induced by oncogenic transcription factors and exhibit enhancer activities. We validate these findings in T-cell acute lymphoblastic leukemia and show that oncogenic NOTCH1 induces specific CTCF binding and they cooperatively activate expression of target genes, indicating transcriptional condensation phenomena. ConclusionsCancer-specific CTCF binding events are not always associated with DNA methylation changes or mutations, but can be induced by other transcription factors to regulate oncogenic gene expression. Our results substantiate CTCF binding alteration as a functional epigenomic signature of cancer.

genomics↗

bioRxiv2019

Minutes-timescale 3D isotropic imaging of entire organs at subcellular resolution by content-aware compressed-sensing light-sheet microscopy

Instant 3D imaging of entire organs and organisms at cellular resolution is a recurring challenge in life science. Here we report on a computational light-sheet microscopy able to achieve minute-timescale mapping of entire macro-scale organs at high spatial resolution, thereby overcoming the throughput limit of current 3D microscopy implementations. Through combining a dual-side confocally-scanned Bessel light-sheet illumination which provides thinner-and-wider optical sectioning of deep tissues, with a content-aware compressed sensing (CACS) computation pipeline which further improves the contrast and resolution based on a single acquisition, our method yields 3D images with high, isotropic spatial resolution and rapid acquisition improved by two-orders of magnitude. We demonstrate the imaging of whole brain ([~]400 mm3), entire gastrocnemius and tibialis muscles ([~]200 mm3) of mouse at subcellular resolution (0.5-m isovoxel) and ultra-high throughput of 5[~]10 minutes per sample. Various system-level cellular analyses, such as mapping cell populations at different brain sub-regions, tracing long-distance projection neurons over the entire brain, and calculating neuromuscular junction occupancy across whole muscle, were also readily enabled by our method.

bioengineering↗

bioRxiv2019

Crl activates transcription by stabilizing the active conformation of the master stress factor σS

{sigma}S is a master transcription initiation factor that protects bacterial cells from various harmful environmental stresses and antibiotic pressure. Although its mechanism remains unclear, it is known that full activation of {sigma}S-mediated transcription requires a {sigma}S-specific activator, Crl. In this study, we determined a 3.80 [A] cryo-EM structure of an E. coli transcription activation complex (E. coli Crl-TAC) comprising E. coli {sigma}S-RNAP holoenzyme, Crl, and a nucleic-acid scaffold. The structure reveals that Crl interacts with the domain 2 of {sigma}S ({sigma}S2), sharing no interaction with promoter DNA. Subsequent hydrogen-deuterium exchange mass spectrometry (HDX-MS) results indicate that Crl stabilizes key structural motifs of {sigma}S2 to promote the assembly of {sigma}S-RNAP holoenzyme and also to facilitate formation of the RNA polymerase-promoter DNA open complex (RPo). Our study demonstrates a unique DNA contact-independent mechanism of transcription activation, thereby defining a previously unrecognized mode of transcription activation in cells.

biochemistry↗

bioRxiv2019

Distinct gut metagenomics and metaproteomics signatures in prediabetics and treatment-naïve type 2 diabetics

BackgroundThe gut microbiota plays important roles in modulating host metabolism. Previous studies have demonstrated differences in the gut microbiome of T2D and prediabetic individuals compared to healthy individuals, with distinct disease-related microbial profiles being reported in groups of different age and ethnicity. However, confounding factors such as anti-diabetic medication hamper identification of the gut microbial changes in disease development.\n\nMethodWe used a combination of in-depth metagenomics and metaproteomics analyses of faecal samples from treatment-naive type 2 diabetic (TN-T2D, n=77), pre-diabetic (Pre-DM, n=80), and normal glucose tolerant (NGT, n=97) individuals to investigate compositional and functional changes of the gut microbiota and the faecal content of microbial and host proteins in Pre-DM and treatment-naive T2D individuals to elucidate possible host-microbial interplays characterising different disease stages.\n\nFindingsWe observed distinct differences characterizing the gut microbiota of these three groups and validated several key features in an independent TN-T2D cohort. We also demonstrated that the content of several human antimicrobial peptides and pancreatic enzymes differed in faecal samples between three groups, such as reduced faecal level of antimicrobial peptides and pancreatic enzymes in TN-T2D.\n\nInterpretationOur findings suggest a complex, disease stage-dependent interplay between the gut microbiota and the host and emphasize the value of metaproteomics to gain further insight into interplays between the gut microbiota and the host.\n\nFundingNational Key Research and Development Program of China, No. 2017YFC0909703, Shenzhen Municipal Government of China, No. JCYJ20170817145809215, and National Natural Science Foundation of China, No. 31601073.

microbiology↗

bioRxiv2019

Age-dependent sexual dimorphism in the adult human gut microbiota

A decade of studies has established the importance of the gut microbiome in human health. In spite of sex differences in the physiology, lifespan, and prevalence of many age-associated diseases, sex and age disparities in the gut microbiota have been little studied. Here we show age-related sex differences in the adult gut microbial composition and functionality in two community-based cohorts from Northern China and the Netherlands. Consistently, women harbour a more diverse and stable microbial community across broad age ranges, whereas men exhibit a more variable gut microbiota strongly correlated with age. Reflecting the sex-biased age-gut microbiota interaction patterns, sex differences observed in younger adults are considerably reduced in the elderly population. Our findings highlight the age- and sex-biased differences in the adult gut microbiota across two ethnic population and emphasize the need for considering age and sex in studies of the human gut microbiota.

genomics↗

bioRxiv2019

Palmitoylation is critically required for cancer intrinsic PD-1 expression and functions

Programmed cell death protein 1 (PD-1) is a crucial anticancer target, but the relatively low response rate and acquired resistance to existing antibody drugs highlight an urgent need to develop alternative targeting strategies. Here we report the palmitoylation of PD-1, discovered the main DHHC enzyme for this modification, revealed the mechanism for its effect on PD-1 expression, and rationally developed a peptide for targeting PD-1 expression. Palmitoylation promoted the trafficking of PD-1 to recycling endosome, thus preventing its lysosome-dependent degradation. Palmitoylation was required for the activation of PD-1 downstream signaling, and targeting palmitoylation by pharmacological inhibitor or depleting the modification enzyme caused significant anti-tumor effects. A peptide was designed to competitively inhibit PD-1 palmitoylation and expression, opening a new route for developing PD-1 inhibitors as a strategy for cancer immunotherapy.\n\nSignificanceWe show for the first time that PD-1 is palmitoylated, identify DHHC9 as the predominant enzyme for its palmitoylation, and reveal the molecular mechanisms underlying its effects on PD-1 stability and functions. Importantly, we also designed a competitive inhibitor targeting PD-1 palmitoylation, and this first-in-class molecule may inspire the development of new checkpoint inhibitors.

cancer biology↗

bioRxiv2019

WinnerTakeAlmostAll: A parsimony approach integrating multi-targets improves marker gene profiling

Amplicon sequencing need to go from using single region to multiple region, one for higher resolution, one for technical replicates. WinnerTakeAlmostAll is an algorithm to calculate a minimum set of references based on the reference-query graph. We showed that this algorithm is superior in resolving species, as well as average out the run effect using technical replicates.

bioinformatics↗

bioRxiv2019

Nonobese subjects of Bacteroides and Prevotella enterotypes responded differentially to calorie restriction intervention

Calorie restriction (CR), which has the potential effect to weight loss and blood amino acids, has been demonstrated to associate with gut microbiota in human, especially in obese individuals. However, studies for simultaneously evaluating enterotype-dependent impacts of CR on the gut microbiota and blood amino acids in nonobese individuals are still limited.\n\nHere, 41 nonobese individuals received a 3-week CR diet with approximately 50% fewer calories than normal diet. We measured their BMI and blood amino acid concentration, along with the gut microbiota before and after the intervention. In this trial, 28 Enterotype Bacteroides (ETB) subjects and 13 Enterotype Prevotella (ETP) subjects were identified before the intervention. Short-term CR dietary intervention decreased the body mass index (BMI) in most subjects but varied in subjects with different enterotypes. ETP subjects exhibited significantly higher BMI loss ratio than the ETB subjects. CR additionally induced substantial enterotype-independent changes in blood amino acids, but only minor changes in gut microbial composition.\n\nWe further built a prediction model based on baseline relative abundances of 7 gut microbial species showing high performance in predicting CR-associated BMI loss ratio. Among them, the relative abundance of ETB-enriched Clostridium bolteae and C. ramosum were negatively correlated with BMI loss ratio while the relative abundance of Dorea longicatena which was slightly enriched in ETP subjects, was positively correlated with BMI loss ratio.\n\nTogether, our work points out that the individual variation of BMI loss after CR could be partially correlated with different microbial composition and highlights the potential application for microbiome stratification in personalized nutrition intervention.

microbiology↗

bioRxiv2018

Genome-wide analysis reveals signatures of selection for gait traits in Yili horse

High quality gaits play an important role in many breeding programs, but the genes of gait were limited at the moment. Here, we present an analysis of genomic selection signatures in 53 individuals from two breeds, using genotype data from the Affymetrix Equine 670K SNP genotyping array. The 11 selection regions of Yili horse were identified using an FST statistic and XP-EHH calculated in 200-kb windows across the genome. In total, 50 genes could be found in the 11 regions, and two candidate genes related to locomotory behavior (CLN6, FZD4). The genome of Yili horse and Russian horse were shaped by natural and artificial selection. Our results suggest that gait trait of Yili horse may related to two genes. This is the first time when whole genome array data is utilized to study genomic regions affecting gait in Yili horse breed.

genetics↗

bioRxiv2018

Desiccation Does Not Drastically Increase the Accessibility of Foreign DNA to the Nuclear Genomes: Evidence from the Frequency of Endosymbiotic DNA Transfer

Horizontal gene transfer (HGT) is a widely accepted force in the evolution of prokaryotic genomes. However, in eukaryotes, it is still in hot debate. Some bdelloid rotifers that are resistant to extreme desiccation and radiation were reported to have a very high level of HGTs. However, a similar report in another resistant invertebrate, tardigrades, has been mired in controversy. The DNA double-strand breaks (DSBs) induced by prolonged desiccation have been postulated to open the gateway of nuclear genome for foreign DNA integration and thus facilitate the HGT process. If so, the rate of endosymbiotic DNA transfer should also be enhanced. We first surveyed the abundance of nuclear mitochondrial DNAs (NUMTs) and nuclear plastid DNAs (NUPTs) in three groups of eukaryotes that are extremely resistant to desiccation, bdelloid rotifers, A. vaga and A. ricciae, tardigrades, H. dujardini and R. varieornatus, and the resurrection plants, D. hygrometricum and S. tamariscina. Excessive NUMTs or NUPTs have not been detected. Furthermore, we compared nine groups of desiccation-tolerant organisms with their desiccation-sensitive relatives but did not find significant difference in the NUMT/NUPT contents. Desiccation could induce DSBs, but it unlikely dramatically increase the frequency of foreign sequence integration in most eukaryotes. Only in the nuclear genomes enriched in repetitive sequences, the DSBs are predominantly repaired by non-homologous end joining (NHEJ) and desiccation-induced DSBs is possible to enhance the integration of foreign sequences into nuclear genome for some degree.

evolutionary biology↗

bioRxiv2018

Flavor compounds in fermented Chinese alcoholic beverage alter gut microbiota and attenuate ethanol-induced liver

Alcoholic beverages which are consumed widely in most parts of the world have long been identified as a major risk factor for all liver diseases, particularly alcohol-induced liver disease (ALD). Recent compositional analyses suggest that Chinese Baijiu (CB), a clear alcoholic liquid distilled from fermented grains, contains large amounts of small molecule bioactive compounds in addition to a significant amount of ethanol. Here, in an experimental mouse model, we show that CB caused lower degrees of liver injury than pure ethanol by protecting against the decrease of the relative abundance of Akkermansia and increased relative abundance of Prevotella in the gut thereby preventing the destruction of the intestinal barrier. Furthermore, we demonstrated that ethanol-induced alteration of the gut microbiota profoundly affected the host metabolome. Compared with ethanol feeding, CB feeding resulted in higher concentrations of functional saturated LCFAs and SCFAs. Our results provide supporting evidence that ALD was profoundly influenced by host-gut microbiota metabolic interactions and that small molecule organic compounds in CB could attenuate ALD.

microbiology↗

bioRxiv2018

Deep-learning light-sheet fluorescence microscopy for high-throughput, voxel-super-resolved imaging of biomedical specimens

Although three-dimensional (3D) fluorescence microscopy is an essential tool for life science research, the fundamentally-limited optical throughput, as reflected in the compromise between speed and resolution, so far prevents further movement towards faster, clearer, and higher-throughput applications. We herein report a dual-stage mutual-feedback deep-learning approach that allows gradual reversion of microscopy degradation from high-resolution targets to low-resolution images. Using a single blurred-and-pixelated 3D image as input, our trained network infers a 3D output with notably higher resolution and improved contrast. The performance is better than conventional 1-stage network approaches. It pushes the throughput limit of current 3D fluorescence microscopy in three ways: notably reducing the acquisition time for accurate mapping of large organs, breaking the diffraction limit for imaging subcellular events with faster lower-toxicity measurement, and improving temporal resolution for capturing instantaneous biological processes. Combining our network approach with light-sheet fluorescence microscopy, we demonstrate the imaging of vessels and neurons in the mouse brain at single-cell resolution and with a throughput of 6 minutes for a whole brain. We also image cell organelles beyond the diffraction limit at a 2-Hz volume rate, and map neuronal activities of freely-moving C. elegans at single-cell resolution and 30-Hz volume rate.

biophysics↗