Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

Ascaris suum transcriptome (RNA-Seq) data

ABSTRACT: Eukaryotic cells express several classes of small RNAs that regulate gene expression and ensure genome maintenance. Endogenous siRNAs (endo-siRNAs) and Piwi-interacting RNAs (piRNAs) mainly control gene and transposon expression in the germline, while microRNAs (miRNAs) generally function in post-transcriptional gene silencing in both somatic and germline cells. To provide an evolutionary and developmental perspective on small RNA pathways in nematodes, we identified and characterized known and novel small RNA classes through gametogenesis and embryo development in the parasitic nematode Ascaris suum and compared them with known small RNAs of Caenorhabditis elegans. piRNAs, Piwi-clade Argonautes, and other proteins associated with the piRNA pathway have been lost in Ascaris. miRNAs are synthesized immediately following fertilization in utero, prior to pronuclear fusion, and before the first cleavage of the zygote. This is the earliest expression of small RNAs ever described at a developmental stage long thought to be transcriptionally quiescent. A comparison of the two classes of Ascaris endo-siRNAs, 22G-RNAs and 26G-RNAs, to those in C. elegans, suggests great diversification and plasticity in the use of small RNA pathways during spermatogenesis in different nematodes. Our data reveal conserved characteristics of nematode small RNAs as well as features unique to Ascaris that illustrate significant flexibility in the use of small RNAs pathways, some of which are likely an adaptation to AscarisM-bM-^@M-^Y life cycle and parasitism. We generated transcriptomes from Ascaris germline and embryos for de-novo assembly as well as cDNA expression profiles. Two types of libraries were prepared: 1) sheared, full-length cDNA synthesized using a combination of oligo-dT and random hexamer priming and 2) cDNA prepared from RNA first chemically sheared and then double-stranded cDNA prepared using ramom hexamer priming.

ORGANISM(S): Ascaris suum

SUBMITTER: Jianbin Wang

PROVIDER: E-GEOD-26956 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

Deep small RNA sequencing from the nematode Ascaris reveals conservation, functional diversification, and novel developmental profiles.

Wang Jianbin J Czech Benjamin B Crunk Amanda A Wallace Adam A Mitreva Makedonka M Hannon Gregory J GJ Davis Richard E RE

Genome research 20110617 9

Eukaryotic cells express several classes of small RNAs that regulate gene expression and ensure genome maintenance. Endogenous siRNAs (endo-siRNAs) and Piwi-interacting RNAs (piRNAs) mainly control gene and transposon expression in the germline, while microRNAs (miRNAs) generally function in post-transcriptional gene silencing in both somatic and germline cells. To provide an evolutionary and developmental perspective on small RNA pathways in nematodes, we identified and characterized known and ...[more]

PMID: 21685128

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Project description:Eukaryotic cells express several classes of small RNAs that regulate gene expression and ensure genome maintenance. Endogenous siRNAs (endo-siRNAs) and Piwi-interacting RNAs (piRNAs) mainly control gene and transposon expression in the germline, while microRNAs (miRNAs) generally function in post-transcriptional gene silencing in both somatic and germline cells. To provide an evolutionary and developmental perspective on small RNA pathways in nematodes, we identified and characterized known and novel small RNA classes through gametogenesis and embryo development in the parasitic nematode Ascaris suum and compared them with known small RNAs of Caenorhabditis elegans. piRNAs, Piwi-clade Argonautes, and other proteins associated with the piRNA pathway have been lost in Ascaris. miRNAs are synthesized immediately following fertilization in utero, prior to pronuclear fusion, and before the first cleavage of the zygote. This is the earliest expression of small RNAs ever described at a developmental stage long thought to be transcriptionally quiescent. A comparison of the two classes of Ascaris endo-siRNAs, 22G-RNAs and 26G-RNAs, to those in C. elegans, suggests great diversification and plasticity in the use of small RNA pathways during spermatogenesis in different nematodes. Our data reveal conserved characteristics of nematode small RNAs as well as features unique to Ascaris that illustrate significant flexibility in the use of small RNAs pathways, some of which are likely an adaptation to AscarisM-bM-^@M-^Y life cycle and parasitism. We constructed and analyzed 51 libraries from discrete regions of gametogenesis and synchronized stages of embryo development in the parasitic nematode Ascaris, using three types of small RNA libraries preparation methods: 1) 28 libraries of 18-34 or 18-40 nt RNAs with a 5M-bM-^@M-^Y monophosphate (5M-bM-^@M-^Y monophosphate libraries), 2) 4 libraries of 18-34 nt RNAs with a 5M-bM-^@M-^Y monophosphate but treated with periodate to enrich for small RNAs with 3M-bM-^@M-^Y end modifications (5M-bM-^@M-^Y monophosphate, 3M-bM-^@M-^Y end modified), and 3) 19 libraries of 18-28 or 18-40 nt RNAs with a 5M-bM-^@M-^Y triphosphate, diphosphate, or monophosphate (5M-bM-^@M-^Y allphosphate). These libraries enabled us to identify different small RNAs, characterize their different 5M-bM-^@M-^Y and 3M-bM-^@M-^Y ends, and their expression profiles through gametogenesis and embryogenesis.

Project description:A long-standing view of development is that transcription is silenced in the oocyte until early divisions in the embryo. The point at which major transcription is reactivated varies in different organisms, but is usually after the 2-cell stage. However, this model may not be universal. We used RNA-seq and exploited the protracted development of the parasitic nematode Ascaris suum, to provide a comprehensive time course of mRNA expression, degradation, and translation during early development. Surprisingly, we find that ~4,000 genes are transcribed prior to pronuclear fusion and in the 1-4 cell embryos. Intriguingly, we do not detect maternal contribution of many orthologs of maternal C. elegans mRNAs, but instead find these are newly transcribed in the A. suum zygote prior to pronuclear fusion. Ribosome profiling demonstrates that, in general, early embryonic mRNAs are not stored for subsequent translation, but are directly translated following their synthesis. The role of maternally contributed and zygotically transcribed genes differs between the nematodes A. suum and C. elegans despite the fact that the two nematodes appear to exhibit highly similar morphological patterns during early development. Our study indicates that major transcription can occur immediately after fertilization and prior to pronuclear fusion in metazoa, suggesting that newly transcribed genes appear to drive A. suum early development. Furthermore, the mechanisms used for controlling the timing of the expression of key conserved genes has been altered between the two nematodes, illustrating significant plasticity in the regulatory networks that play important roles in developmental outcomes in nematodes. A total of 28 samples are used for this study. The RNAs for the library construction are derived from 0.5 M-bM-^@M-^S 1 ml of synchronized embryo stages corresponding to a minimum of 0.5 billion embryos derived from > 1,000 female worms. The RNAs for polysome analysis are from pooled fractions of polysome gradient. For each sample, the amount of RNA for all polysome fractions is equivalent to the total RNA from the sample. Thus, the data from polysome profiling and RNA transcriptomes are considered as biological replicates. The level of the RNAs between each neighboring stages during development are considered as the reference for each other. Different sequencing strategies were applied for multiple libraries.

Dataset Information

Ascaris suum transcriptome (RNA-Seq) data

Publications

Deep small RNA sequencing from the nematode Ascaris reveals conservation, functional diversification, and novel developmental profiles.

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