Megason
03-04-2012, 09:14 PM
Based on evidence gathered on this discussion board (thanks Rick, John, and Rod), it appears that snakeskin is controlled by an allele that is dominant with regards to the snakeskin pigment pattern phenotype (closely spaced stripes or spots and 14 stress bars) as well as being recessive for early embryonic lethality. Lets call the snakeskin gene Ss.
If this hypothesis is true, when we cross Ss/+ X Ss/+ we should get:
25% +/+ (wildtype)
50% Ss/+ (snakeskin phenotype)
25% Ss/Ss (dead)
This would explain why you cannot fix snakeskin (it never breeds true) and why the phenotype seems to appear at 67% which is not a typical Mendellian frequency.
To confirm this hypothesis, I would like to examine a clutch of snakeskin eggs (Ss/+ X Ss/+) under a microscope for the first week or so after fertilization to see if 25% of the eggs die with a characteristic phenotype. I will take pictures and post them to the group.
I am looking for volunteers who currently have breeding pairs of snakeskin and are willing to send me a clutch of eggs by FedEx!
Collect the eggs as you would for artificially raising them. Namely, a few hours after spawning remove the adults to a different tank. While leaving the breeding cone underwater, gently scrape off the eggs into the water with a plastic knife and let them settle to the bottom. Put a glass underwater in the tank and gently sweep the eggs in the glass. Remove the glass with the eggs from the water and pour off any excess water. Pour the eggs and the water into a container suitable for mailing and close. A suitable container should be plastic with a watertight screw top and hold 1 cup of water. Small plastic bottles for water, Gatorade, or soda are fine, just rinse them out well. Fill the bottle with the eggs and tank water until half full and leave the other half with air. Screw on the top tightly and place the bottle in a ziplock bag just in case it leaks. Place in a shipping box and ship to me FedEx. Email me at megason AT hms.harvard.edu and I’ll send you my address and FedEx number so shipping is free. I'm a "professional" geneticist by the way. I need >100 eggs for good statistics.
If all goes well, I may try to sequence the genome of the snakeskin mutants to identify which gene is mutated. For this to work, it is important that I know the parents of the parents used for the cross (i.e. the grandparents of the shipped embryos). At least one and ideally 2 of the grandparents should NOT be snakeskin.
If this hypothesis is true, when we cross Ss/+ X Ss/+ we should get:
25% +/+ (wildtype)
50% Ss/+ (snakeskin phenotype)
25% Ss/Ss (dead)
This would explain why you cannot fix snakeskin (it never breeds true) and why the phenotype seems to appear at 67% which is not a typical Mendellian frequency.
To confirm this hypothesis, I would like to examine a clutch of snakeskin eggs (Ss/+ X Ss/+) under a microscope for the first week or so after fertilization to see if 25% of the eggs die with a characteristic phenotype. I will take pictures and post them to the group.
I am looking for volunteers who currently have breeding pairs of snakeskin and are willing to send me a clutch of eggs by FedEx!
Collect the eggs as you would for artificially raising them. Namely, a few hours after spawning remove the adults to a different tank. While leaving the breeding cone underwater, gently scrape off the eggs into the water with a plastic knife and let them settle to the bottom. Put a glass underwater in the tank and gently sweep the eggs in the glass. Remove the glass with the eggs from the water and pour off any excess water. Pour the eggs and the water into a container suitable for mailing and close. A suitable container should be plastic with a watertight screw top and hold 1 cup of water. Small plastic bottles for water, Gatorade, or soda are fine, just rinse them out well. Fill the bottle with the eggs and tank water until half full and leave the other half with air. Screw on the top tightly and place the bottle in a ziplock bag just in case it leaks. Place in a shipping box and ship to me FedEx. Email me at megason AT hms.harvard.edu and I’ll send you my address and FedEx number so shipping is free. I'm a "professional" geneticist by the way. I need >100 eggs for good statistics.
If all goes well, I may try to sequence the genome of the snakeskin mutants to identify which gene is mutated. For this to work, it is important that I know the parents of the parents used for the cross (i.e. the grandparents of the shipped embryos). At least one and ideally 2 of the grandparents should NOT be snakeskin.