Hello, my name is Yoshihito Niimura
from the University of Miyazaki, Japan.
The title of my talk is Major Gene Families
in Humans and Their Evolutionary History.
This is the content of my talk.
First, I'd like to talk
about a multigene family.
A multigene family is a group of genes that
have descended from a common ancestor and,
therefore, have similar functions
and similar DNA sequences.
Historically, a Japanese
geneticist Yoshinari Kuwada,
has mentioned the possibility of chromosome
duplication by observing the chromosomes of maize.
Later, Susumu Ohno published a book entitled
Evolution by Gene Duplication in 1970
and postulated that gene duplication
played a major role in evolution.
A gene duplication generates
two copies of the same gene.
In this situation, it is easier to gain an over function,
because one copy functions as a spare of the original gene.
Therefore, the other gene can alter its
function without losing its original function.
Hemoglobin provides a classical
example of gene duplication.
It is well known that hemoglobin in red blood cells of
humans is composed of four subunits; two α and two β chains.
There are also γ and δ chains, which are mainly
used in fetuses and newborns, respectively.
In 1961, Ingram proposed that the genes encoding hemoglobin
α, β, γ and δ chains were generated by gene duplication.