IUBio Biosequences .. Software .. Molbio soft .. Network News .. FTP

Determining ploidy

biosci-request at net.bio.net biosci-request at net.bio.net
Tue Jun 22 17:58:26 EST 1999


Crona O'Conallain asked:

> I am interested in having the ploidy of a polyploid strain of S.
> cerevisiae determined and was wondering if anybody could recommend a good
> method for doing this and a company/institute that could provide the
> service. I was thinking of perhaps FISH analysis but do not know what
> company/institute to approach. All suggestions regarding other methods or
> an institute/company that provides FISH analysis of S. cerevisiae would be
> most appreciated.

If you are set up to do it, you could also use a genetic approach.  
1) Does the strain mate?  If it mates with alpha, it is a, a/a, a/a/a, 
a/a/a/a, etc.  If it mates with a, it must be alpha, alpha/alpha, etc.  
To distinguish among these, sporulate and dissect tetrads from the 
mated strains.  If your original strain was a and you mate it with an 
alpha, you should get decent spore viability with mating type 
segregating 2:2.  If your original strain was a/a and you mate it with 
alpha, the resulting triploid will produce very few viable spores.  If 
your original strain was a/a/a and you mate it with alpha, you will 
make a tetraploid that should give good spore viability and roughly 
half nonmating (a/alpha) and half a-mating (a/a) segregants.

You get the idea.  Of course, if the strain is homothallic that will 
make the analysis messier.

2) the second question you can ask is does your strain sporulate?  
If it does it has at least one a and one alpha allele at MAT.  
Dissect tetrads and determine spore viability--triploids will be very 
low; tetraploids will be higher.  Tetraploids that are a/a/alpha/alpha 
will give rise to a mixture of a/a, a/alpha, and alpha/alpha 
segregants while a/a/a/alpha will give a/a and a/alpha and 
a/alpha/alpha/alpha will give a/alpha and alpha/alpha.


Beth A. Montelone, Ph. D, Associate Professor
Division of Biology, Ackert Hall
Kansas State University
Manhattan, KS  66506-4901
phone (785) 532-6092; fax (785) 532-6653
web site http://www-personal.ksu.edu/~bethmont





______________O_________oO_____________oO______o_______oO___________________
YEAST bionet newsgroup see: http://www.bio.net/hypermail/YEAST/
YEAST e-mail: messages sent to yeast at net.bio.net
subscribe: e-mail biosci-server at net.bio.net with: subscribe yeast
unsubscribe: e-mail biosci-server at net.bio.net with: unsubscribe yeast
YEAST on the WWW: http://genome-www.stanford.edu/Saccharomyces/VL-yeast.html
problems with the YEAST newsgroup? E-mail the moderator: francis at cmmt.ubc.ca




More information about the Yeast mailing list

Send comments to us at biosci-help [At] net.bio.net