English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Background  Dorsal spine reduction in threespine sticklebacks ( Gasterosteus aculeatus ) is a classic example of recurrent skeletal evolution in nature. Sticklebacks in marine environments typically have long spines that form part of their skeletal armor. Many derived freshwater populations have evolved shorter spines. Changes in spine length are controlled in part by a quantitative trait locus (QTL) previously mapped to chromosome 4, but the causative gene and mutations underlying the repeated evolution of this interesting skeletal trait have not been identified.    Results  Refined mapping of the spine length QTL shows that it lies near the  MSX2A  transcription factor gene.  MSX2A  is expressed in developing spines. In F1 marine × freshwater fish, the marine allele is preferentially expressed.  Differences in expression can be attributed to splicing regulation. Due to the use of an alternative 5  ′  splice site within the first exon, the freshwater allele produces greater amounts of a shortened, non-functional transcript and makes less of the full-length transcript. Sequence changes in the  MSX2A  region are shared by many freshwater fish, suggesting that repeated evolution occurs by reuse of a spine-reduction variant.  To demonstrate the effect of full-length  MSX2A  on spine length, we produced transgenic freshwater fish expressing a copy of marine  MSX2A . The spines of the transgenic fish were significantly longer on average than those of their non-transgenic siblings, partially reversing the reduced spine lengths that have evolved in freshwater populations.    Conclusions    MSX2A  is a major gene underlying dorsal spine reduction in freshwater sticklebacks. The gene is linked to a separate gene controlling bony plate loss, helping explain the concerted effects of chromosome 4 on multiple armor-reduction traits. The nature of the molecular changes provides an interesting example of morphological evolution occurring not through a simple amino acid change, nor through a change only in gene expression levels, but through a change in the ratio of splice products encoding both normal and truncated proteins.    Electronic supplementary material  The online version of this article (doi:10.1186/s12915-017-0456-5) contains supplementary material, which is available to authorized users.

Dorsal spine evolution in threespine sticklebacks via a splicing change in MSX2A