Has everyone seen this "white" page?

Talk about equine color, markings, genetics, etc. Post pictures of flashy Thoroughbreds!

Moderators: Roguelet, WaveMaster, Jorge, Sunday Silence

User avatar
summerhorse
Breeder's Cup Winner
Posts: 2178
Joined: Wed Oct 26, 2005 6:40 am
Location: Panama City, FL
Contact:

Has everyone seen this "white" page?

Postby summerhorse » Sat Nov 05, 2011 10:35 pm

I believe I talked to this poster on TB Champions or another forum before about Mount Blanc and his family. Unfortunately it seems they have lost interest in keeping the page up to date. :(

http://perloch.ps.free.fr/sire/pscouleu ... blanc.html

Unfortunately I don't speak french!
Every mighty oak was once an acorn that stood its ground.

kimberley mine
Breeder's Cup Contender
Posts: 1811
Joined: Tue Jan 11, 2005 8:43 pm

Postby kimberley mine » Tue Nov 08, 2011 6:16 am

La robe blanche comme la robe grise est dominante. C'est à dire que pour avoir un blanc il faut avoir un parent blanc... enfin normalement. Pourquoi il y a-t-il des pur sang anglais blancs, palominos alors qu'aucune lignée initiale ne l'était ?
Les pur sang anglais blancs sont apparus spontanéement. Sont-elles dues à des mutations ponctuelles où à erreurs de croisements ? Les moyens de la génétique actuelles permettraient effectivement de différencier ces cas mais dans ses chevaux sont apparus avant le contrôle de filliation par génotypage.
Cas d'une mutation ponctuelle :
Lors de la fabrication des gamètes ( ovules ou spermatozoïdes) les chromosomes s'emmêlent, l'ADN ne se sépare pas bien, il suffit qu'un de ces constituants, un nucléotide soit perdu ou échangé, le gène est modifié : La protéine pour lequel il code ne s'exprime pas, en quantité différente ou sous une autre forme et la pigmentation ne se fait pas ou anormalement.


Cas d'erreurs de croisement :
Le papa n'est pas le papa présumé, et c'est un vrai blanc d'une autre race qui est passé par là...


This isn't a literal translation--it's quite faithful, but intended to read more as a native english speaker would write it.

The white coat, like a grey coat, is dominant. That is to say, to have a white one must have a white parent....usually. Why, then, are there thoroughbreds with white and palomino coats with no white or palomino parents?

These white thoroughbreds have appeared spontaneously. Are they due to new mutations, or errors in the studbook? New genetic testing techniques can differentiate between the two, but some of these horses were born before DNA parentage testing.

In case of a new mutation:

During production of gametes (egg and sperm) the chromosomes form and sometimes do not separate properly. Occasionally a nucleotide is lost or its position is swapped, and the gene is modified: the protein either does not express at all, causes atypical expressions, or gives rise to another coat colour entirely.

User avatar
summerhorse
Breeder's Cup Winner
Posts: 2178
Joined: Wed Oct 26, 2005 6:40 am
Location: Panama City, FL
Contact:

Postby summerhorse » Tue Nov 08, 2011 9:55 pm

Thanks! Too bad it appears to be abandoned.
Every mighty oak was once an acorn that stood its ground.