Dataset Information

A consensus approach to vertebrate de novo transcriptome assembly from RNA-seq data: assembly of the duck (Anas platyrhynchos) transcriptome.

ABSTRACT: For vertebrate organisms where a reference genome is not available, de novo transcriptome assembly enables a cost effective insight into the identification of tissue specific or differentially expressed genes and variation of the coding part of the genome. However, since there are a number of different tools and parameters that can be used to reconstruct transcripts, it is difficult to determine an optimal method. Here we suggest a pipeline based on (1) assessing the performance of three different assembly tools (2) using both single and multiple k-mer (MK) approaches (3) examining the influence of the number of reads used in the assembly (4) merging assemblies from different tools. We use an example dataset from the vertebrate Anas platyrhynchos domestica (Pekin duck). We find that taking a subset of data enables a robust assembly to be produced by multiple methods without the need for very high memory capacity. The use of reads mapped back to transcripts (RMBT) and CEGMA (Core Eukaryotic Genes Mapping Approach) provides useful metrics to determine the completeness of assembly obtained. For this dataset the use of MK in the assembly generated a more complete assembly as measured by greater number of RMBT and CEGMA score. Merged single k-mer assemblies are generally smaller but consist of longer transcripts, suggesting an assembly consisting of fewer fragmented transcripts. We suggest that the use of a subset of reads during assembly allows the relatively rapid investigation of assembly characteristics and can guide the user to the most appropriate transcriptome for particular downstream use. Transcriptomes generated by the compared assembly methods and the final merged assembly are freely available for download at http://dx.doi.org/10.6084/m9.figshare.1032613.

SUBMITTER: Moreton J

PROVIDER: S-EPMC4070175 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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A consensus approach to vertebrate de novo transcriptome assembly from RNA-seq data: assembly of the duck (Anas platyrhynchos) transcriptome.

Moreton Joanna J Dunham Stephen P SP Emes Richard D RD

Frontiers in genetics 20140625

For vertebrate organisms where a reference genome is not available, de novo transcriptome assembly enables a cost effective insight into the identification of tissue specific or differentially expressed genes and variation of the coding part of the genome. However, since there are a number of different tools and parameters that can be used to reconstruct transcripts, it is difficult to determine an optimal method. Here we suggest a pipeline based on (1) assessing the performance of three differe ...[more]

PMID: 25009556

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Project description:Background: Skeletal muscle growth and development is highly orchestrated in gene expressions. Understanding the location-specific and breed-specific genes and pathways are agriculturally important on meat products and meat quality. In the present study, RNA-Seq was performed to elucidate the difference of muscle deposition between locations and breeds for functional genomics studies. To achieve those goals, skeletal muscle samples were collected for pectoral muscle (PM) and leg muscle (LM) of two genetically different duck breeds, Heiwu duck (H) and Peking duck (P), at embryonic 15 days. Functional genomics studies were performed in two experiments: Experiment 1 directly compared location-specific genes between PM and LM, while Experiment 2 compared the two breeds (H and P) at the same development stage (embryonic 15 days). Results: Almost 13 million clean reads was generated using Illumina technology on each library, and more than 70% reads mapped to Anas platyrhynchos breed Peking duck genome. We identified 246, 258, 20 and 54 differentially expressed genes (DEGs) (log2.fold-change >0.5, and P-value <0.05) for H-PM vs H-LM, P-PM vs P-LM, H-LM vs P-LM and H-PM vs P-PM library, separately. A total of 168 genes were differentially expressed by over locations in experiment 1, while only 8 genes were differentially expressed by over breeds in experiment 2. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes pathways (KEGG) were used to functionally annotate DGEs. In experiment 1, DEGs mainly involved in Focal adhesion, PI3K-Akt signaling pathway and ECM-receptor interaction pathways (corrected P-value<0.05). In experiment 2, DEGs only associated with ribosome signal pathway (corrected P-value<0.05). In addition, quantitative real-time PCR was employed to confirm 15 differentially expressed genes detected by RNA-Seq. Conclusions: Comparative transcript analysis of leg muscle and pectoral muscle of two duck breeds not only improves our understanding of those location-specific and breed-specific genes and pathways, but also provides some candidate molecular targets for increase muscle products and meat quality by genetic control. Conclusions: Our study represents the first detailed analysis of duck breed muscle transcriptomes generated by RNA-seq technology. The optimized data analysis workflows reported here should provide a framework for comparative investigations of expression profiles. Our results show that NGS offers a comprehensive and more accurate quantitative and qualitative evaluation of mRNA content within a cell or tissue. We conclude that RNA-seq based transcriptome characterization would expedite genetic network analyses and permit the dissection of complex biologic functions.

Project description:BackgroundIn birds, blue-green eggshell color (BGEC) is caused by biliverdin, a bile pigment derived from the degradation of heme and secreted in the eggshell by the shell gland. Functionally, BGEC might promote the paternal investment of males in the nest and eggs. However, little is known about its formation mechanisms. Jinding ducks (Anas platyrhynchos) are an ideal breed for research into the mechanisms, in which major birds lay BGEC eggs with minor individuals laying white eggs. Using this breed, this study aimed to provide insight into the mechanisms via comparative transcriptome analysis.ResultsBlue-shelled ducks (BSD) and white-shelled ducks (WSD) were selected from two populations, forming 4 groups (3 ducks/group): BSD1 and WSD1 from population 1 and BSD2 and WSD2 from population 2. Twelve libraries from shell glands were sequenced using the Illumina RNA-seq platform, generating an average of 41 million clean reads per library, of which 55.9% were mapped to the duck reference genome and assembled into 31,542 transcripts. Expression levels of 11,698 genes were successfully compared between all pairs of 4 groups. Of these, 464 candidate genes were differentially expressed between cross-phenotype groups, but not for between same-phenotype groups. Gene Ontology (GO) annotation showed that 390 candidate genes were annotated with 2234 GO terms. No candidate genes were directly involved in biosynthesis or transport of biliverdin. However, the integral components of membrane, metal ion transport, cholesterol biosynthesis, signal transduction, skeletal system development, and chemotaxis were significantly (P < 0.05) overrepresented by candidate genes.ConclusionsThis study identified 464 candidate genes associated with duck BGEC, providing valuable information for a better understanding of the mechanisms underlying this trait. Given the involvement of membrane cholesterol contents, ions and ATP levels in modulating the transport activity of bile pigment transporters, the data suggest a potential association between duck BGEC and the transport activity of the related transporters.

Dataset Information

A consensus approach to vertebrate de novo transcriptome assembly from RNA-seq data: assembly of the duck (Anas platyrhynchos) transcriptome.

Publications

A consensus approach to vertebrate de novo transcriptome assembly from RNA-seq data: assembly of the duck (Anas platyrhynchos) transcriptome.

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