CEM Seminar – Kateryna Makova
Pentz Professor of Biology
Pennsylvania State University
Deciphered Gorilla Y chromosome shows strong conservation with Human but not with Chimpanzee
The mammalian Y chromosome plays a critical role in sex determination and male fertility. Yet the Y, enriched in repeats and palindromes, is the most difficult to assemble component of the genome. Previously, expensive and labor-intensive BAC-based techniques were used to sequence the Y for a handful of mammalian species. Among great apes, only human and chimpanzee Y chromosomes were sequenced. Here, using flow-sorting, short- and long-read sequencing technologies, and a variety of assembly algorithms, we produce a draft assembly of the gorilla Y. Combined with transcript-assisted scaffolding and ampliconic gene family size evaluation via droplet digital PCR, these procedures constitute a fast and affordable set of methods for reconstructing a sex chromosome from a heterogametic sex. Our results attest to strong conservation in structure and gene content between the gorilla and human Y chromosomes, and portray the chimpanzee Y as an outlier in the hominine Y chromosome evolution, even though chimpanzee and human shared the most recent common ancestor. Compared with the human Y, the chimpanzee Y lost four X-degenerate genes, three ampliconic gene families, and one palindrome, while the gorilla Y retained all these elements with the exception of one gene family. The ampliconic gene family size varies dramatically among the three hominines, as well as intraspecifically for four genes in gorilla. We speculate that the Y chromosome evolution in hominines is associated with their mating patterns. Additionally, the gorilla Y chromosome sequence was used to design polymorphic genetic markers for tracing male-specific dispersal in this endangered species.
Dr. Makova did her PhD with Robert Baker at Texas Tech University. She then did a postdoc with Wen-Hsiung Li at the University of Chicago. She has been running her own laboratory at Penn State University since 2003.