Recent research has uncovered a crucial microRNA that plays a significant role in the survival of male birds. This discovery sheds light on the unique mechanisms birds employ to balance gene activity between sexes, differing from those in mammals.
In birds, males possess two Z chromosomes (ZZ), while females have one Z and one W chromosome (ZW). Over evolutionary time, the W chromosome in females has lost many genes, creating an imbalance where males have two copies of certain genes, and females have only one. This disparity can lead to developmental issues if not properly regulated.
Scientists have identified a microRNA, known as miR-2954, that is predominantly active in male birds. This microRNA acts as a regulatory mechanism, modulating the activity of genes on the Z chromosome to prevent overexpression in males. When this microRNA was removed from male chicken embryos, the embryos failed to develop, indicating its essential role in male survival.
This finding highlights the distinct evolutionary strategies birds have developed to address genetic imbalances between sexes. Unlike mammals, which compensate through mechanisms like X-inactivation, birds utilize specific microRNAs to fine-tune gene expression, ensuring proper development and survival.
The study, led by researchers from Heidelberg University and the University of Edinburgh, provides valuable insights into avian genetics and opens avenues for further exploration into sex chromosome regulation across different species.