分类: 信息化
2014-03-27 08:57:11
The trick is you have two copies of every gene, Brooks said. “Sometimes a particular mutation with only one copy may be recognised as beneficial but later down the line if you have an individual with two copies, the recessive effect might actually produce a disease.
That’s because every gene in a mammal’s body isn’t just being used for one thing. The protein it encodes is a multipurpose tool. “Each of these genes is multitasking. It’s a pretty efficient way to do things, Brooks said. “Sometimes the negative effects are in some of these other things that a gene does. When we make a change in gene X, what are the other processes that it might affect
The same gene that helps control appaloosas’ melanin expression in their coats also plays a role in their eyes. The situation is similar in miniaturising horses. As they get smaller, the genes that limit the growth of their skeletons can cause negative impacts. Sometimes breeders attempting to create miniature horses end up with dwarfs that have malfunctioning jaws and legs. They can be crippled. While breeders obviously try to avoid that situation, it can be difficult for them to know which mating pairs will lead to negative outcomes.