genetics questions ...

["Simon" <svavev@hunterlink.net.au>]

Are there any geneticists out there on this mailing list ?

If so, I have a few queries about krib genetics;

1. Male krib are the only ones that develop eyespots. Does this mean that
the development of eyespots is a sex-linked ( X-linked ) characteristic ?

2. This is my understanding of the term sex-linkage ( x-linkage ). Is it
more or less correct;

If a characteristic such as tail eyespots is sex-linked then the female
carries a gene on the x-chromosome which determines tail ornamentation. In
females the presence of two of these genes on the two X chromosomes means
that the tail is clear of tail spots. In males the same gene on its  X
chromosome will be unpaired because the Y chromosome is basically an empty
chromosome ( i.e. they are hemizygous for the tail ornamentation gene ). So
when this combination is expressed it is read to code for eyespots instead
of a clear tail. So X+X+ = clear tail ( + symbols meant to be superscripted
and do not reflect an addition of X to X but rather the tail ornamentation
gene located on the X chromosome ) and X+Y = spotted tail and because the X-
gene does not exist it is not possible for females to possess tail eye
spots.

3. If tail eye-spots are a sex-linked gene, does that mean that the choice
of females used in a breeding program to increase the number of tail spots
is irrelevant or could the number of tail spots be determined by a gene
which is not located on an autosome ?

Regards,

Simon

http://thecichlidtank.cjb.net



-------------------------------------------------------------------------
This is the apistogramma mailing list, apisto@listbox.com.
For instructions on how to subscribe or unsubscribe or get help,
email apisto-request@listbox.com.
Search http://altavista.digital.com for "Apistogramma Mailing List Archives"!