DNA is the focal point of reproductive activity

According to a new study published by Imperial biologist in PNAS in April, there is one type of wild yeast every 1,000 generations of asexual reproduction that exists in a sexual reproduction cycle.

The study focused on yeast Saccharomyces paradoxus, a yeast that can reproduce in both sexual and asexual forms. The team used this enzyme to test the effect of sexual and asexual reproduction on various changes in the DNA sequence of organisms. A DNA sequence as the 'blueprint' of an organism includes the chemical structures needed for genes to grow and function.

Through analysis of DNA sequences of wild yeast, scientists have found the rate of sexual reproduction in yeast by recording special signs of both sexual and asexual reproduction on the DNA sequence.

Saccharomyces cells.(Photo: Wikimedia Commons)

When yeast reproduces asexually, a mother cell produces a small nipple, which detaches to become identical daughter cells to the mother cells. In the process of nipple formation, the original DNA of the mother cell is copied, sometimes making mistakes in the process of making mutations. Mutations occur in all generations, they can be used to distinguish asexual species and their numbers are used to determine the number of asexual generations. On the other hand, if yeast reproduces sexually, the genetic material in the mother cell implements a process of division and recombination to create a new living organism. The result is a new combination of genes on the daughter cell's DNA sequence. This suggests that sexual reproduction creates a new body while asexual reproduction does not.

Isheng Jason Tsai - graduate student of Imperial Life Sciences and an author of the article - explained the importance of recognizing when different forms of reproduction appear:

'Finding special signs left by different forms of yeast reproduction gives us valuable insights into the life cycle of organisms that are difficult to study. The study brings new light sources to microbial works later on as well as their reproduction . '

Jason and his colleagues analyzed changes in the DNA sequence of a chromosome in two wild yeast populations Saccharomyces paradoxus.

By analyzing the DNA sequence of the yeast, the researchers were able to assess the extent of DNA alteration due to asexual reproduction, and the degree of alteration of DNA by sexual reproduction. The level of variation increases with the number of individuals in the population, and is used to estimate population size.

Comparing two forms of genes allows them to conclude that men S. paradoxus go through 1,000 generations of asexual reproduction, having a generation of sexual reproduction.

Article 'Genome of wild yeast populations Saccharomyces paradoxus: Determining the number of life cycles' published online March 14.