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

Wang, Jianbin and Czech, Benjamin and Crunk, Amanda and Wallace, Adam and Mitreva, Makedonka and Hannon, Gregory J. and Davis, Richard E. (2011) Deep small RNA sequencing from the nematode Ascaris reveals conservation, functional diversification, and novel developmental profiles. Genome Research, 21. pp. 1462-1477.

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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 after fertilization in utero, before 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 Ascaris’ life cycle and parasitism.

Item Type: Article
Subjects: Medical and Health Sciences > Basic medicine
Divisions: Faculty of Medical Science
Depositing User: Mirjana Kocaleva
Date Deposited: 30 Nov 2012 15:18
Last Modified: 30 Nov 2012 15:18
URI: http://eprints.ugd.edu.mk/id/eprint/2676

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