News: DNA clues to reproductive behaviour
- From: "Robert Karl Stonjek" <rstonjek@xxxxxxxxxxxxxx>
- Date: Tue, 20 May 2008 13:49:25 -0400 (EDT)
DNA clues to reproductive behaviour
A species of wild yeast goes through a cycle of sexual reproduction once in
every 1,000 asexual generations, according to new research by Imperial
biologists published in the PNAS journal in April.
The study focused on the wild yeast Saccharomyces paradoxus, which is able
to reproduce both sexually and asexually. The scientific team used this
yeast to examine how sexual and asexual reproduction cause different types
of variations in an organism's DNA sequence. A DNA sequence is like an
organism's 'blueprint' - a complete set of chemical instructions needed for
it to grow and function.
The researchers analysed the DNA sequences of wild yeast and discovered how
infrequently the yeast reproduces sexually by noting the unique 'signatures'
sexual and asexual reproduction leave in the yeast's DNA sequence.
When the yeast reproduces asexually a mother cell generates a bud, which
becomes detached, creating a new daughter cell, identical to the mother
cell. During the budding process, the original DNA of the mother cell is
copied, and occasionally mistakes are made, known as mutations. As these
mutations occur in every generation, they can be used to distinguish asexual
lineages and their total number can be used to estimate the number of
asexual generations in a population.
On the other hand, if the yeast reproduces sexually, the mother cell's
genetic material undergoes a process of division and recombination to create
a new living organism. As a result of this recombining process new
combinations of genes can be found in the offspring's DNA sequence, which
indicate that the new organism was created by sexual, as opposed to asexual,
reproduction.
Isheng Jason Tsai, a postgraduate student in Imperial's Department of Life
Sciences, one of the authors of the paper, explains why being able to
identify when different reproductive methods have occurred is important:
"Finding the unique signatures left by different types of reproduction on
the yeast's DNA gives us valuable insights into the life cycle of this
species, which is otherwise very difficult to study. This research has shed
new light on the study of microbes, and their patterns of reproduction."
Jason and his colleagues analysed variations in the DNA sequence of one
particular chromosome in two populations of the wild yeast Saccharomyces
paradoxus.
By analysing the yeast's DNA sequences, the researchers were able to
estimate rates of DNA variation caused by asexual reproduction, and rates of
DNA variation caused by sexual reproduction. Both these two rates increase
with the number of individuals in the population and can be used to estimate
population size.
Comparing the estimates from these two different types of DNA variation
enabled them to conclude that S. paradoxus goes through a sexual cycle
approximately once every thousand asexual generations.
The paper, "Population genomics of the wild yeast Saccharomyces paradoxus:
Quantifying the life cycle" was published online on 14 March. It can be
downloaded here: http://www.pnas.org/cgi/content/abstract/105/12/4957 .
Source: Imperial College London
http://www.physorg.com/news130425156.html
Posted by
Robert Karl Stonjek
.
- Prev by Date: Call for Papers with Extended Deadline of June 1, 2008:
- Next by Date: Speaking of cnidarians...
- Previous by thread: Call for Papers with Extended Deadline of June 1, 2008:
- Next by thread: Speaking of cnidarians...
- Index(es):
Relevant Pages
|
|
