The Drosophila fertility factor kl-3 is linked to the Y-chromosome of the vector of Chagas’ disease Triatoma infestans (Hemiptera: Reduviidae) and is essential for male fertility

Abstract

In many insects, the Y chromosome plays a key role in sexual determination and male fertility. The Chagas disease vector Triatoma infestans has 22 autosomal chromosomes and a pair of XY sex chromosomes. However, the knowledge on the Y chromosome of this species, its genetic content or its biological function, is very poor. Due to repetitive DNA, Y chromosome sequences are poorly assembled in genome projects, hindering structural and functional studies on Y-linked genes. Our group has developed many of the bioinformatic tools to identify Y-linked sequences in assembled genomes. Here, we describe the identification of a {gamma}-dynein heavy chain linked to the Y-chromosome of T. infestans. This protein is orthologous to the Drosophila melanogaster Y-linked gene kl-3. In D. melanogaster, dyneins of the Y chromosome are known as male fertility factors and their deletion causes male infertility. We performed knockdown of the kl-3 expression to ascertain its function in T. infestans. Our results showed that injection of dsKL3 reduced, significantly, the fertility of T. infestans males (p<0.01). The mean number of eggs laid by the control group was 35.64 eggs/couple while the kl-3 knockdown group was of 11.82 eggs/couple (five couples did not lay any eggs). Differences in eclosion rate was even more significant, with a hatching mean rate of 16.85{+/-}10.03 and 1.69{+/-}3.58 (p<0.001) for the control and the silenced groups respectively. Our results suggest that kl-3 maintains its functional role as essential for male fertility in T. infestans. Hence, it seems that the Y-chromosome of T. infestans has a key role in male fertility. This is the first report of a kl-3 orthologue linked to the Y chromosome of an insect species outside the diptera clade. In addition to the first report of a Y-linked gene in T. infestans with a role for male fertility, this finding is of great relevance for the study of the evolution of Y chromosomes and further studies that could lead to novel approaches in insect control.