Abstract
Tbxt and the disappearance of the tail in great apes and humans. Targeted approach. Hox genes and tail formation. Global analysis of intraspecific evolutionary variants.
This third lesson begins with a brief reminder of some of the key points developed in lesson 2, in particular concerning the study of a recent publication implicating the Tbxt gene in the loss of the tail in great apes, some 25 million years ago. The possible cause would be the insertion of a small repeat sequence that would induce exon skipping and thus the production of a protein slightly shorter than the normal protein, which is nevertheless still present, in the same quantity as the small protein. Problems of interpretation are discussed with regard to the different doses of this reduced protein needed to induce a shorter tail in mice, which do not seem to correspond to the situation in humans. This discussion concludes with an analysis of the two reading levels associated with this publication and the difficulty of objectifying scientific results when they touch on issues of societal interest, both by the authors themselves and by the editorial policies of major journals.
Then, a second publication is described which addresses the same question of tail length evolution, but tackles it in a different way, at the level of mouse populations evolving in different habitats, and using the tools of quantitative genetics which enable the isolation of quantitative trait loci (QTL), when complex multi-gene genetic architectures are encountered. In the system under discussion, no fewer than six different quantitative loci are involved in the variations in tail length observed in two ecotypes of the deer mouse peromyscus maniculatus.
