White (mutation)

white
A white-eyed Drosophila
Identifiers
OrganismDrosophila melanogaster
Symbolw1
UniProtP10090
Other data
ChromosomeX: 2.79 - 2.8 Mb
Search for
StructuresSwiss-model
DomainsInterPro

white, abbreviated w, was the first sex-linked mutation discovered, found in the fruit fly Drosophila melanogaster. In 1910 Thomas Hunt Morgan and Lilian Vaughan Morgan collected a single male white-eyed mutant from a population of Drosophila melanogaster fruit flies, which usually have dark brick red compound eyes. Upon crossing this male with wild-type female flies, they found that the offspring did not conform to the expectations of Mendelian inheritance.[1] The first generation (the F1) produced 1,237 red-eyed offspring and three white-eyed male flies. The second generation (the F2) produced 2,459 red-eyed females, 1,011 red-eyed males, and 782 white-eyed males. Further experimental crosses led them to the conclusion that this mutation was somehow physically connected to the "factor" that determined sex in Drosophila. This led to the discovery of sex linkage, in which the gene for a trait is found on a sex chromosome. Morgan named this trait white, now abbreviated w.[2] Flies possessing the white allele are frequently used to introduce high school and college students to genetics.

Experimental cross performed by Thomas Hunt Morgan, illustrating the X-linked inheritance of white in Drosophila.[3]
  1. ^ Morgan TH (July 1910). "Sex Limited Inheritance in Drosophila". Science. 32 (812): 120–2. Bibcode:1910Sci....32..120M. doi:10.1126/science.32.812.120. PMID 17759620.
  2. ^ As the field of genetics developed, names for genes were italicized, and for Drosophila the normal (wild type) allele was given a + modifier, for example w+. Names of commonly used mutations were shortened, and since white was the first named, it was shortened to a single letter.
  3. ^ Morgan TH (1919). The physical basis of heredity. Philadelphia: J.B. Lippincott Company.