19 April Thesis defense Ábel Vértesy: the germline at the single-cell level Back to news Ábel Vértesy, PhD, Hubrecht researcher in the group of Alexander van Oudenaarden, studied the reproductive cells of the human body and in model organisms such as the nematode C. elegans at the single-cell level. Vértesy graduated on April 19th, 2018. During his PhD, Vértesy researched the function of the germline – the cells that contribute to reproduction such as the ova and sperm cells. These are the only cells in an organism that pass on genetic information to the next generation. As a result, understanding how germline cells work is essential for fertility research. Single-cell sequencing To gain insight in the function of germline cells, Vértesy studied the female human germline during fetal development using single-cell RNA sequencing. This technology allows researchers to determine the gene expression profile of individual cells. First, a single cell is sorted, its mRNA is multiplied and the material receives a molecular barcode. Next, the mRNA of various cells can be combined and analyzed. The barcode allows researchers to trace back the data to the original cell. Therefore, these experiments give us information on the genes expressed by each individual cell in the germline. Gene expression Vértesy and his colleagues concluded that there is a difference in the way female germline cells regulate their gene expression. Some of those genes – imprinted genes – are activated in a strict order, while the X-chromosomal genes seem to activate without a defined order. The scientists also studied the male germ cells in mice. They found that genes on the sex chromosomes (X and Y chromosomes) are silenced in a sequential order. Furthermore, Vértesy and his colleagues created a gene expression atlas of the nematode (round worm) C. elegans, a commonly used model system in developmental biology. The researchers used this atlas to map differences between the two sexes of the worm and to describe which genes that are specific for male germline cells. Fertility During his PhD, Vértesy has been the first one to study the germline in a resolution on the single-cell level. This knowledge helps us understand the function of the germline and the developmental differences between male and female germline cells. Research into the germline has a clinical relevance because of the steady decline of human fertility in western countries.