ABSTRACT: Taxonomically different symbiotic communities of sympatric Arctic sponge species show functional similarity with specialization at species level
Project description:Small RNAs (sRNAs) are a taxonomically-restricted but transcriptomically-abundant class of post-transcriptional regulators. While potentially of importance, we know the function of few. This is in no small part because we lack global-scale methodology enabling target identification, this being especially acute in species without known RNA meeting point proteins (e.g. Hfq). We apply a combination of psoralen RNA cross-linking and Illumina-sequencing to identify RNA-RNA interacting pairs in vivo in Bacillus subtilis, resolving previously well-described interactants. Although sRNA-sRNA pairings are rare (compared with sRNA/mRNA), we identify a robust example involving the unusually conserved sRNA (RoxS/RsaE) and an unstudied sRNA that we term Regulator of small RNA A (RosA). This interaction is found in independent samples across multiple conditions. Given the possibility of a novel associated regulatory mechanism, and the rarity of well-characterised bacterial sRNA-sRNA interactions, we mechanistically dissect RosA and its interactants. RosA we show to be a sponge RNA, the first to be described in a Gram-positive bacterium. RosA interacts with at least two sRNAs, RoxS and FsrA. Unexpectedly, it acts differently on each. As expected of a sponge RNA, FsrA is sequestered by RosA. The RosA/RoxS interaction is more complex affecting not only the level of RoxS but also its processing and efficacy. Importantly, RosA provides the condition-dependent intermediary between CcpA, the key regulator of carbon metabolism, and RoxS. This not only provides evidence for a novel, and functionally important, regulatory mechanism, but in addition, provides the missing link between transcriptional and post-transcriptional regulation of central metabolism.
Project description:Arctic Mesorhizobium strain N33 was isolated from nodules of the Oxytropis arctobia in Canada’s eastern Arctic. This symbiotic bacterium can grow from 0 to 30°C, is one of the best known cold-adapted rhizobia, and can fix nitrogen at ~10°C. Here, the key molecular mechanisms of cold adaptation were investigated by determining changes in transcript profiles when cells were treated under eight different temperature conditions, including both sustained and transient cold treatments compared with cells grown at room temperature.
Project description:We investigated whether two sympatric Arctic charr morphs (Salvelinus alpinus) with contrasting feeding ecology, the small-benthic (SB) and the planktivorous (PL) charr of Thingvallavatn in Iceland, exhibit genetically based differences in gene expression variability, and how dominance would affect their hybrids. Through a common-garden experiment, we identified genes clusters with similar expression variability, most differing among the two morphs. In the hybrids, gene expression variability was substantially affected by maternal effects and biases towards the PL charr, while the expression of a minority of genes felt outside the range of parental values. These profiles of expression variability were consistent across mRNA and miRNA datasets. Predominant maternal effects and PL charr biases were also observed at the level of average gene expression, including candidate genes involved in the lower jaw development.
2023-01-01 | GSE193797 | GEO
Project description:Gut microbial diversity and ecological specialization in four sympatric lemur species under lean conditions
Project description:Poorly conserved or taxonomically-restricted genes represent a sizable portion of most genomes. Many of these genes participate in essential processes and can contribute to evolutionary innovation in species. However, identifying which genes are biologically important and uncovering their functions remains a significant challenge, since routine tools reliant on gene ontology or sequence orthology are of limited use. Here we evaluate two genes of the Caenorhabditis-restricted class of LIN-15B-domain-encoding genes, ivph-3 and gon-14, and compare their in vivo functions in two species, C. elegans and C. briggsae. We show that within the Elegans supergroup of Caenorhabditis, ivph-3 and gon-14 exhibit sequence constraints distinct from other family members, including maintenance of a one-to-one orthology and a higher degree of stabilizing selection. Coincidentally, mutants for either of the genes exhibit strong phenotypic defects that are similar within-species (C. elegans or C. briggsae), but with notable differences when comparing between species. These findings highlight the genetic and genomic features associated with the evolution of a taxonomically restricted gene family, and suggest mechanisms by which specific family members adapt to fulfill essential biological functions.
Project description:Three sympatric species of Caribbean grunts (H. flavolineatum, H. carbonarium and H. macrostomum) were collected while SCUBA diving. RNA was extracted from livers, and the transcriptomes were assembled and annotated to investigate positive selection (Pairwise dN/dS) and patterns of gene expression between the three species.