Abstract
BackgroundThe evolutionary radiation of animals was accompanied by extensive expansion of gene and genome sizes, increased isoform diversity, and complexity of regulation.ResultsHere we show that the longest genes are enriched for expression in neuronal tissues of diverse vertebrates and of invertebrates. Additionally, we show that neuronal gene size expansion occurred predominantly through net gains in intron size, with a positional bias toward the 5′ end of each gene.ConclusionsWe find that intron and gene size expansion is a feature of many genes whose expression is enriched in nervous systems. We speculate that unique attributes of neurons may subject neuronal genes to evolutionary forces favoring net size expansion. This process could be associated with tissue-specific constraints on gene function and/or the evolution of increasingly complex gene regulation in nervous systems.
Highlights
The evolutionary radiation of animals was accompanied by extensive expansion of gene and genome sizes, increased isoform diversity, and complexity of regulation
Neuronal long gene expression is apparent in invertebrates, such as the insect arthropod, Drosophila melanogaster, and the cephalopod mollusc, Octopus bimaculoides (Fig. 1a)
Intron and gene size expansion provide one mechanism by which existing components can be modified to increase transcriptomic potential from a limited gene complement, contributing to the evolution of novelty [6, 54] and potentially to the molecular complexity that is a hallmark of nervous systems
Summary
The evolutionary radiation of animals was accompanied by extensive expansion of gene and genome sizes, increased isoform diversity, and complexity of regulation. Exact transcription rates are unknown, assuming the estimated average rates of transcription in eukaryotes of 1–4 kb per minute [9, 10], the 2.3 Mb human gene CNTNAP2 would require upwards of 10 h to generate one transcript, which is substantially longer than the 10 min required for the average mammalian gene ~ 10 kb in length [11]. This phenomenon, termed intron delay, biases patterns of expression and evolution of gene structure for a substantial portion of the transcriptome [12, 13]. Recent transcriptomic studies in rodents and humans have revealed that
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
