Context

Scientists have unlocked enzyme ‘SPRK1’ that reorganises paternal genome during fertilisation. The enzyme makes way for the first step, folding and packaging the sperm so that it fits in the egg.

About

• A person’s genome is inherited from the parents — during fertilisation, half of the father’s genome is mixed with half of the mother’s.
• A sperm carries half as much genetic material as a regular cell and needs to be folded and packaged in a way that it fits in the egg.
• It is the enzyme SPRK1 that makes way for this first step, by reorganising paternal genome during the first moments of fertilisation.
• The enzyme does it in a matter of few hours.
• The study, published in journal Cell, was carried out by researchers at University of California San Diego School of Medicine discovered.
• Until now, enzyme SPRK1 was studied for its ability to splice ribonucleic acid (RNA) — an important step that enables translation of genes to proteins.
• But SRPK1 leads a double life, swapping protamines for histones once the sperm meets egg.
• SPRK1 most likely started out playing this role in early embryogenesis, and later evolved the ability to splice RNA. That was how SPRK1 got to do the latter even when it was no longer needed for embryogenesis.

Understanding the science behind it:

• Our standard knowledge of human reproduction is clear: sperm, fertilize the egg, the embryo develops, and finally a new baby is born.
• However, scientists did not know exactly the process of how half the genome of sperm from the father and half of the egg from the mother came together.
• Sperm can be up to 20 times smaller than a normal cell in the body. And while sperm carry only half as much genetic material as a regular cell, it needs to be folded and packaged in a special way in order to fit.
• One way nature does this is by replacing histones - proteins around which DNA is wound, like beads on a necklace, with a different type of protein called protamines.

Significance of the discovery:

• The scientists have uncovered a step that might malfunction for some people, and contribute to a couple’s difficulty conceiving. The discovery could help study infertility in certain cases.
• To date, researchers did not really know much about these relatively brief, yet crucial, incipient moments in fertilisation. The discovery simply answers a fundamental question about the beginning of life.