speck, First Identified in Drosophila melanogaster in 1910, Is Encoded by the Arylalkalamine N-Acetyltransferase (AANAT1) Gene.

Journal Article (Journal Article)

The pigmentation mutation speck is a commonly used recombination marker characterized by a darkly pigmented region at the wing hinge. Identified in 1910 by Thomas Hunt Morgan, speck was characterized by Sturtevant as the most "workable" mutant in the rightmost region of the second chromosome and eventually localized to 2-107.0 and 60C1-2. Though the first speck mutation was isolated over 110 years ago, speck is still not associated with any gene. Here, as part of an undergraduate-led research effort, we show that speck is encoded by the Arylalkylamine N-acetyltransferase 1 (AANAT1) gene. Both alleles from the Morgan lab contain a retrotransposon in exon 1 of the RB transcript of the AANAT1 gene. We have also identified a new insertion allele and generated multiple deletion alleles in AANAT1 that all give a strong speck phenotype. In addition, expression of AANAT1 RNAi constructs either ubiquitously or in the dorsal portion of the developing wing generates a similar speck phenotype. We find that speck alleles have additional phenotypes, including ectopic pigmentation in the posterior pupal case, leg joints, cuticular sutures and overall body color. We propose that the acetylated dopamine generated by AANAT1 decreases the dopamine pool available for melanin production. When AANAT1 function is decreased, the excess dopamine enters the melanin pathway to generate the speck phenotype.

Full Text

Duke Authors

Cited Authors

  • Spana, EP; Abrams, AB; Ellis, KT; Klein, JC; Ruderman, BT; Shi, AH; Zhu, D; Stewart, A; May, S

Published Date

  • September 2, 2020

Published In

Volume / Issue

  • 10 / 9

Start / End Page

  • 3387 - 3398

PubMed ID

  • 32709620

Pubmed Central ID

  • PMC7466976

Electronic International Standard Serial Number (EISSN)

  • 2160-1836

Digital Object Identifier (DOI)

  • 10.1534/g3.120.401470


  • eng

Conference Location

  • England