Project description:Small RNA pathways play evolutionarily conserved roles in gene regulation and in defense from pathogenic and parasitic nucleic acids. The character and expression patterns of small RNAs show conservation throughout animal lineages, but specific animal clades also show variations on these recurring themes, including species-specific small RNAs. The monotremes, with only platypus and four species of echidna as extant members, represent the basal branch of the mammalian lineage. Here, we examine the small RNA pathways of monotremes by deep sequencing of six platypus and echidna tissues. We find that highly conserved microRNA species display their signature tissue-specific expression patterns. In addition, we find a large rapidly-evolving cluster of miRNAs on platypus chromosome X1 which is unique to monotremes. Platypus and echidna testes contain a robust piRNA system which appears to be participating in ongoing transposon defense. Keywords: piRNA
Project description:Small RNA pathways play evolutionarily conserved roles in gene regulation and in defense from pathogenic and parasitic nucleic acids. The character and expression patterns of small RNAs show conservation throughout animal lineages, but specific animal clades also show variations on these recurring themes, including species-specific small RNAs. The monotremes, with only platypus and four species of echidna as extant members, represent the basal branch of the mammalian lineage. Here, we examine the small RNA pathways of monotremes by deep sequencing of six platypus and echidna tissues. We find that highly conserved microRNA species display their signature tissue-specific expression patterns. In addition, we find a large rapidly-evolving cluster of miRNAs on platypus chromosome X1 which is unique to monotremes. Platypus and echidna testes contain a robust piRNA system which appears to be participating in ongoing transposon defense. Keywords: piRNA Two size fractions of small RNAs (18-24nt and 25-33nt) were cloned and sequenced from platypus adult testis total RNA; one size fraction (28-24nt) was cloned and sequenced from echidna adult testis total RNA
Project description:Gene dosage imbalance of heteromorphic sex chromosomes (XY or ZW) exists between the sexes, and with the autosomes. Mammalian X chromosome inactivation was long thought to imply a critical need for dosage compensation in vertebrates. However, mRNA abundance measurements that demonstrated sex chromosome transcripts are neither balanced between the sexes or with autosomes in monotreme mammals or birds brought sex chromosome dosage compensation into question. This study examines transcriptomic and proteomic levels of dosage compensation in platypus and chicken compared to mouse, a model eutherian species. We analyzed mRNA and protein levels in heart and liver tissues of chicken, mouse and platypus.