Studies of rearrangements involving heterochromatin in Drosophila melanogaster. I. A proof of variegated-type position effect at the white locus. II. A study of the heterochromatin of chromosome IV

• Main Author: Judd, Burke Haycock
• Format: Others
• Published: 1954
• Online Access: https://thesis.library.caltech.edu/182/1/Judd_BH_1954.pdf; Judd, Burke Haycock (1954) Studies of rearrangements involving heterochromatin in Drosophila melanogaster. I. A proof of variegated-type position effect at the white locus. II. A study of the heterochromatin of chromosome IV. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/4F9F-MV78. https://resolver.caltech.edu/CaltechETD:etd-01152004-095338 <https://resolver.caltech.edu/CaltechETD:etd-01152004-095338>

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. The X-IV translocation, [...], is shown to contain the wild-type allele, [...], at the white locus. This [...] has been replaced with a mutant gene, w, and a comparison of R([...])/w with R(w)/w[...] shows the former to give a variegated white phenotype while the latter is completely wild-type. It is concluded that the white variegation is due to an instability in the action of [...] when it is located in the rearranged chromosome. Cold temperature enhances variegation particularly when applied during the embryonic stages of development. A less sensitive period is found to exist during the pupal stages. These facts indicate the white gene is active during more than a single period of development. Twelve duplication-deficiency types have been obtained by combining the left and right parts of four X-IV translocations. Tests for survival of these combinations in the haplo-IV condition give somewhat contradictory results. These results are discussed and a possible order for the fourth chromosome translocation breaks is given.