Accelerated Evolution of Limb-Related Gene Hoxd11 in the Common Ancestor of Cetaceans and Ruminants (Cetruminantia)

Molecular Mechanisms Underlying Vertebrate Adaptive Evolution: A Systematic Review

Adaptive evolution is a process in which variation that confers an evolutionary advantage in a specific environmental context arises and is propagated through a population. When investigating this process, researchers have mainly focused on describing advantageous phenotypes or putative advantageous genotypes. A recent increase in molecular data accessibility and technological advances has allowed researchers to go beyond description and to make inferences about the mechanisms underlying adaptive evolution. In this systematic review, we discuss articles from 2016 to 2022 that investigated or reviewed the molecular mechanisms underlying adaptive evolution in vertebrates in response to environmental variation. Regulatory elements within the genome and regulatory proteins involved in either gene expression or cellular pathways have been shown to play key roles in adaptive evolution in response to most of the discussed environmental factors. Gene losses were suggested to be associated with an adaptive response in some contexts. Future adaptive evolution research could benefit from more investigations focused on noncoding regions of the genome, gene regulation mechanisms, and gene losses potentially yielding advantageous phenotypes. Investigating how novel advantageous genotypes are conserved could also contribute to our knowledge of adaptive evolution.

Gene expression changes during the evolution of the tetrapod limb

Major changes in the vertebrate anatomy have preceded the conquest of land by the members of this taxon, and continuous changes in limb shape and use have occurred during the later radiation of tetrapods. While the main, conserved mechanisms of limb development have been discerned over the past century using a combination of classical embryological and molecular methods, only recent advances made it possible to identify and study the regulatory changes that have contributed to the evolution of the tetrapod appendage. These advances include the expansion of the model repertoire from traditional genetic model species to non-conventional ones, a proliferation of predictive mathematical models that describe gene interactions, an explosion in genomic data and the development of high-throughput methodologies. These revolutionary innovations make it possible to identify specific mutations that are behind specific transitions in limb evolution. Also, as we continue to apply them to more and more extant species, we can expect to gain a fine-grained view of this evolutionary transition that has been so consequential for our species as well.

First DNA sequence proof for the occurrence of bovine adenovirus types 10 and 11 in continental Europe

Bovine adenoviruses (BAdV) are known to cause respiratory and/or intestinal disease in calves. Infection can manifest as acute outbreaks, but more often only sporadic cases occur. Here we describe the PCR detection and partial sequence characterization of several BAdVs found in sick or dead calves on different farms in Western Hungary. Intermittent diarrhoeal illnesses occurred after weaning among calves on several farms located up to 40 km apart. A high-sensitivity, broad-spectrum nested PCR, developed for the general detection of adenoviruses, gave positive results in four independent cases. Direct sequencing of PCR products showed clear results from only two samples, whereas sequences from the other two amplicons were mixed. Molecular cloning of these heterogeneous PCR products was performed to separate each DNA fragment therein. By sequencing several plasmid clones from both mixed samples, we were able to detect the simultaneous presence of two different BAdV types, namely types 6 and 10 classified into two separate (Atadenovirus and Mastadenovirus) genera. The sequence of one homogenous sample was identified as being derived also from BAdV-10, whereas the other sample contained a novel type, proposed to be BAdV-11. We demonstrated, for the very first time, the occurrence of the two latter virus types in continental Europe. Their appearance in Hungary marks a significant shift in the types of BAdVs actually circulating in the country. Considering the similarity of the pathological findings to those, attributed to BAdV-10 infections reported to date, the causative role of the viruses in these cases seems to be plausible. Phylogeny reconstruction further confirmed that BAdVs represent multiple genetic lineages.