Biology subjects

Wu, Y.

Publications and source records attributed to Wu, Y..

1,104 records · Page 62Linked to original sources

bioRxiv2017

GAPPadder: A Sensitive Approach for Closing Gaps on Draft Genomes with Short Sequence Reads

BackgroundClosing gaps in draft genomes is an important post processing step in genome assembly. It leads to more complete genomes, which benefits downstream genome analysis such as annotation and genotyping. Several tools have been developed for gap closing. However, these tools dont fully utilize the information contained in the sequence data. For example, while it is known that many gaps are caused by genomic repeats, existing tools often ignore many sequence reads that originate from a repeat-related gap.\n\nResultsIn this paper, we propose a new approach called GAPPadder for gap closing. The main advantage of GAPPadder is that it uses more information in sequence data for gap closing. In particular, GAPPadder finds and uses reads that originate from repeate-related gaps. We show that these repeat-associated reads are useful for gap closing, even though they are ignored by all existing tools. Other main features of GAPPadder include utilizing the information in sequence reads with different insert sizes and performing two-stage local assembly of gap sequences. We compare GAPPadder with GapCloser, GapFiller and Sealer on one bacterial genome, human chromosome 14 and the human whole genome with paired-end and mate-paired reads with both short and long insert sizes. Empirical results show that GAPPadder can close more gaps than these existing tools. Besides closing gaps on draft genomes assembled only from short sequence reads, GAPPadder can also be used to close gaps for draft genomes assembled with long reads. We show GAPPadder can close gaps on the bed bug genome and the Asian sea bass genome that are assembled partially and fully with long reads respectively. We also show GAPPadder is efficient in both time and memory usage. The software tool, GAPPadder, is available for download at https://github.com/Reedwarbler/GAPPadder.

bioinformatics↗

bioRxiv2017

Generation And Comparative Analysis Of Full-Length Transcriptomes In Sweetpotato And Its Putative Wild Ancestor I. trifida

Sweetpotato [Ipomoea batatas (L.) Lam.] is one of the most important crops in many developing countries and provides a candidate source of bioenergy. However, neither high-quality reference genome nor large-scale full-length cDNA sequences for this outcrossing hexaploid are still lacking, which in turn impedes progress in research studies in sweetpotato functional genomics and molecular breeding. In this study, we apply a combination of second- and third-generation sequencing technologies to sequence full-length transcriptomes in sweetpotato and its putative ancestor I. trifida. In total, we obtained 53,861/51,184 high-quality transcripts, which includes 34,963/33,637 putative full-length cDNA sequences, from sweetpotato/I. trifida. Amongst, we identified 104,540/94,174 open reading frames, 1476/1475 transcription factors, 25,315/27,090 simple sequence repeats, 417/531 long non-coding RNAs out of the sweetpotato/I. trifida dataset. By utilizing public available genomic contigs, we analyzed the gene features (including exon number, exon size, intron number, intron size, exon-intron structure) of 33,119 and 32,793 full-length transcripts in sweetpotato and I. trifida, respectively. Furthermore, comparative analysis between our transcript datasets and other large-scale cDNA datasets from different plant species enables us assessing the quality of public datasets, estimating the genetic similarity across relative species, and surveyed the evolutionary pattern of genes. Overall, our study provided fundamental resources of large-scale full-length transcripts in sweetpotato and its putative ancestor, for the first time, and would facilitate structural, functional and comparative genomics studies in this important crop.

plant biology↗

bioRxiv2017

A new organotypic model of synaptic competition reveals activity-dependent localization of C1q

Immature neural circuits undergo synaptic refinement, in which activity-dependent competition between synapses results in pruning of inappropriate connections and maintenance of appropriate ones. A longstanding question is how neuronal activity eliminates specific synapses based on their strength. The technical challenges of in vivo studies have made it difficult to identify a molecular link between decreased activity and synapse elimination. We developed an organotypic coculture model of the mouse retinogeniculate system that facilitates real-time imaging and elucidation of molecular mechanisms underlying the removal of less active synapses during synaptic competition. Using this model we show for the first time that complement component C1q is necessary for activity-dependent synaptic competition and preferentially localizes to less active, competing presynaptic inputs. In conjunction with classic in vivo and ex vivo models, this coculture model is a new tool to reveal molecular pathways underlying CNS circuit refinement.

neuroscience↗

bioRxiv2016

A Deep Boosting Based Approach for Capturing the Sequence Binding Preferences of RNA-Binding Proteins from High-Throughput CLIP-Seq Data

Characterizing the binding behaviors of RNA-binding proteins (RBPs) is important for understanding their functional roles in gene expression regulation. However, current high-throughput experimental methods for identifying RBP targets, such as CLIP-seq and RNAcompete, usually suffer from the false positive and false negative issues. Here, we develop a deep boosting based machine learning approach, called DeBooster, to accurately model the binding sequence preferences and identify the corresponding binding targets of RBPs from CLIP-seq data. Comprehensive validation tests have shown that DeBooster can outperform other state-of-the-art approaches in predicting RBP targets and recover false negatives that are common in current CLIP-seq data. In addition, we have demonstrated several new potential applications of DeBooster in understanding the regulatory functions of RBPs, including the binding effects of the RNA helicase MOV10 on mRNA degradation, the influence of different binding behaviors of the ADAR proteins on RNA editing, as well as the antagonizing effect of RBP binding on miRNA repression. Moreover, DeBooster may provide an effective index to investigate the effect of pathogenic mutations in RBP binding sites, especially those related to splicing events. We expect that DeBooster will be widely applied to analyze large-scale CLIP-seq experimental data and can provide a practically useful tool for novel biological discoveries in understanding the regulatory mechanisms of RBPs. The scource code of DeBooster can be downloaded from http://github.com/dongfanghong/deepboost.

bioinformatics↗

bioRxiv2016

Tractography-based connectomes are dominated by false-positive connections

Fiber tractography based on non-invasive diffusion imaging is at the heart of connectivity studies of the human brain. To date, the approach has not been systematically validated in ground truth studies. Based on a simulated human brain dataset with ground truth white matter tracts, we organized an open international tractography challenge, which resulted in 96 distinct submissions from 20 research groups. While most state-of-the-art algorithms reconstructed 90% of ground truth bundles to at least some extent, on average they produced four times more invalid than valid bundles. About half of the invalid bundles occurred systematically in the majority of submissions. Our results demonstrate fundamental ambiguities inherent to tract reconstruction methods based on diffusion orientation information, with critical consequences for the approach of diffusion tractography in particular and human connectivity studies in general.

neuroscience↗

bioRxiv2016

Chimeric Genes Revealed in the Polyploidy Fish Hybrids of Carassius cuvieri (Female) x Megalobrama amblycephala (Male)

The genomes of newly formed natural or artificial polyploids may experience rapid gene loss and genome restructuring. In this study, we obtained tetraploid hybrids (4n=148, 4nJB) and triploid hybrids (3n=124, 3nJB) derived from the hybridization of two different subfamily species Carassius cuvieri ([female], 2n = 100, JCC) and Megalobrama amblycephala ([male], 2n = 48, BSB). Some significant morphological and physiological differences were detected in the polyploidy hybrids compared with their parents. To reveal the molecular traits of the polyploids, we compared the liver transcriptomes of 4nJB, 3nJB and their parents. The results indicated high proportion chimeric genes (31 > %) and mutated orthologous genes (17 > %) both in 4nJB and 3nJB. We classified 10 gene patterns within three categories in 4nJB and 3nJB orthologous gene, and characterized 30 randomly chosen genes using genomic DNA to confirm the chimera or mutant. Moreover, we mapped chimeric genes involved pathways and discussed that the phenotypic novelty of the hybrids may relate to some chimeric genes. For example, we found there is an intragenic insertion in the K+ channel kcnk5b, which may be related to the novel presence of the barbels in 4nJB. Our results indicated that the genomes of newly formed polyploids experienced rapid restructuring post-polyploidization, which may results in the phenotypic and phenotypic changes among the polyploidy hybrid offspring. The formation of the 4nJB and 3nJB provided new insights into the genotypic and phenotypic diversity of hybrid fish resulting from distant hybridization between subfamilies.

developmental biology↗