Scientists have succeeded in analyzing the entire sequence of the Y chromosome, a task previously unaccomplished. This provides valuable information on its role in sperm production.
- Half of the Y chromosome had not been decoded by science.
- Scientists have managed to decipher the millions of repetitions it contains.
- This has led to a better understanding of its role in fertility.
The secrets of the Y chromosome are revealed. The 23 pairs that every human wears have been studied extensively by scientists. But the Y chromosome, which only men have, was still poorly understood. Science had not managed to analyze more than half of its sequence. But a team of around a hundred scientists managed to decode it in its entirety. In the magazine Nature, these researchers reveal the importance of this chromosome, particularly in reproduction.
Y chromosome: why is it so difficult to decipher?
“All chromosomes have repetitive sectors, but the Y chromosome is unusually repetitive, making its sequence particularly difficult to complete.explain the authors in their study. Gathering sequencing data is like trying to read a long book cut into strips. If all the lines in the book are unique, it’s easier to determine the order in which they go. However, if the same sentence is repeated thousands or millions of times, the original order of the strips is much less clear.”
This group of scientists used new DNA sequencing techniques and computational tools to successfully decipher these millions of repetitions. “We didn’t know exactly what made up the missing sequence, warns Adam Phillippy, head of this consortium. It could have been very chaotic, but instead almost half of the chromosome is made up of alternating blocks of two specific repetitive sequences called satellite DNA.”
What is the role of the Y chromosome?
This complete sequencing also makes it possible to understand the characteristics of each sector of this chromosome. One of them is called the azoospermia factor region, it contains several genes involved in sperm production. Thanks to recent discoveries, researchers have been able to study inverted repeats, also called palindromes, in this area. “This structure is very important because these palindromes can sometimes create DNA loops, says Arang Rhie, co-author. Sometimes these loops are accidentally cut and create deletions in the genome.“However, deletions in the region of the azoospermia factor disrupt sperm production, so these palindromes could influence fertility. The work of the consortium will allow us to better understand their impact on sperm production. But they also succeeded in decoding a gene called TSPY, also linked to sperm production: they discovered that individuals have between 10 and 40 copies of this gene, which could again improve the understanding of male fertility.
Y chromosome: what will these discoveries do about the genome?
“When you discover variations you’ve never seen before, the hope is always that these genomic variants become important for understanding human health“, estimates Dr Adam Phillippy. According to him, this work could make it possible to develop new, more effective diagnostic tools. Ultimately, the discoveries will potentially contribute to better management of infertility. According toWorld Health Organizationit affects 186 million people worldwide.