A century's progression from the chromosomal theory of inheritance

Dr CharuSudan

A hundred years ago, in 1916, CB Bridges published a paper in the journal GENETICS, describing  the occurrence of meiotic non-disjunction in the fruit fly Drosophila.

C.B. BRIDGES, “NON-DISJUNCTION AS PROOF OF THE CHROMOSOME THEORY OF HEREDITY(concluded),” GENETICS, 1:107-63, 1916.

He presented his results in the form of meticulous drawings illustrating the karyotypes of various flies. Some of the flies expressed sex-linked phenotypes which were against the pattern exhibited by X-linked gene. When their chromosomes were analysed, they showed Non-disjunction of the X chromosomes. This was the first evidence for non-disjunction of chromosomes.

More important was the fact that behaviour, or in this case, misbehaviour (error in the separation) of a specific chromosome ie the X chromosome was associated with unusual inheritance of certain phenotypic traits in the fruit fly. 

This provided confirmatory evidence for the the chromosomal theory of inheritance; the theory that says that genes are located on chromosomes.    

Check out this article in the May 2016 issue of  the journal 'The Scientist' . 

Picturing Inheritance, 1916

This year marks the centennial of Calvin Bridges’s description of nondisjunction as proof that chromosomes are vehicles for inheritance. 

http://www.the-scientist.com/?articles.view/articleNo/45886/title/Picturing-Inheritance--1916/