fruitless (gene)

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fruitless
Identifiers
OrganismDrosophila melanogaster
Symbolfru
Entrez42226
RefSeq (mRNA)NM_169821.1
RefSeq (Prot)NP_732349.1
UniProtQ8IN81
Other data
Chromosome3R: 14.22 - 14.39 Mb

The fruitless gene (fru) is a Drosophila melanogaster gene that encodes several variants of a putative transcription factor protein. Normal fruitless function is required for proper development of several anatomical structures necessary for courtship, including motor neurons which innervate muscles needed for fly sexual behaviors.[1] The gene does not have an obvious mammalian homolog, but appears to function in sex determination in species as distant as the mosquito Anopheles gambiae.[2]

fruitless serves as an example of how a gene or a group of genes may regulate the development and/or function of neurons involved in innate behavior. Research on fruitless has received attention in the popular press, since it provokes discussion on genetics of human sexual orientation,[3][4] and behaviors such as gender-specific aggression.[5]

Function[]

Male flies with mutations in the fruitless gene display altered sexual behavior. Fruitfly courtship, which involves a complex male-initiated ritual, may be disrupted in many ways by mutated fru alleles; fru is necessary for every step in the ritual. Some alleles prevent courting entirely, while others disrupt individual components. Notably, some loss-of-function alleles change or remove sexual preference.[1]

Although many genes are known to be involved in male courtship behavior, the fruitless gene has been considered noteworthy because it exhibits sex-specific alternative splicing. When females produce the male-spliced gene product, they behave as males. Males that do not produce the male-specific product do not court females and are infertile.[1] In the brain, a subset (ca. 2,000) of neurons express fruitless[6] and fruitless expression is sufficient to instruct sexually dimorphic connectivity. [7][8]

fruitless has at least four promoters, each encoding proteins containing both a BTB (Broad complex/tramtrack/bric-a-brac) domain and a zinc finger motif. Alternative splicing occurs at both the 5' and 3' ends, and there are several variants (other than the male- and female-specific splicing patterns).[1] The fruitless gene locus also controls the expression of hundreds of other genes,[9] any subset of which may actually regulate behavior.

Name[]

Early work refers to the gene as fruity, an apparent pun on both the common name of D. melanogaster, the fruit fly, as well as a slang word for homosexual. As social attitudes towards homosexuality changed, fruity came to be regarded as offensive, or at best, not politically correct. Thus, the gene was re-dubbed fruitless, alluding to the lack of offspring produced by flies with the mutation.[10] However, despite the original name and a continuing history of misleading inferences by the popular media, fruitless mutants primarily show defects in male-female courtship, though certain mutants cause male-male or female-female courtship.[11]

References[]

  1. ^ a b c d Demir E, Dickson BJ (June 2005). "fruitless splicing specifies male courtship behavior in Drosophila". Cell. 121 (5): 785–94. doi:10.1016/j.cell.2005.04.027. PMID 15935764. S2CID 14663286.
  2. ^ Gailey DA, Billeter JC, Liu JH, Bauzon F, Allendorfer JB, Goodwin SF (March 2006). "Functional conservation of the fruitless male sex-determination gene across 250 Myr of insect evolution". Molecular Biology and Evolution. 23 (3): 633–43. doi:10.1093/molbev/msj070. PMID 16319090.
  3. ^ Burr C (June 1997). "Homosexuality and Biology, The Genetic Quest". The Atlantic.
  4. ^ Wade N (December 13, 1996). "Mating Game of Fruit Fly Is Traced to a Single Gene". The New York Times.
  5. ^ Sample, Ian (November 20, 2006). "Flies reveal gene that makes girls fight like boys". The Guardian.
  6. ^ Cachero S, Ostrovsky AD, Yu JY, Dickson BJ, Jefferis GS (September 2010). "Sexual dimorphism in the fly brain". Current Biology. 20 (18): 1589–601. doi:10.1016/j.cub.2010.07.045. PMC 2957842. PMID 20832311.
  7. ^ Kohl J, Ostrovsky AD, Frechter S, Jefferis GS (December 2013). "A bidirectional circuit switch reroutes pheromone signals in male and female brains". Cell. 155 (7): 1610–23. doi:10.1016/j.cell.2013.11.025. PMC 3898676. PMID 24360281.
  8. ^ Ruta V, Datta SR, Vasconcelos ML, Freeland J, Looger LL, Axel R (December 2010). "A dimorphic pheromone circuit in Drosophila from sensory input to descending output". Nature. 468 (7324): 686–90. Bibcode:2010Natur.468..686R. doi:10.1038/nature09554. PMID 21124455. S2CID 4412743.
  9. ^ Goldman TD, Arbeitman MN (November 2007). "Genomic and functional studies of Drosophila sex hierarchy regulated gene expression in adult head and nervous system tissues". PLOS Genetics. 3 (11): e216. doi:10.1371/journal.pgen.0030216. PMC 2082469. PMID 18039034.
  10. ^ Gailey DA, Hall JC (April 1989). "Behavior and cytogenetics of fruitless in Drosophila melanogaster: different courtship defects caused by separate, closely linked lesions". Genetics. 121 (4): 773–85. PMC 1203660. PMID 2542123.
  11. ^ "GeneBrief - fruitless". InteractiveFly. Society for Developmental Biology.

External links[]

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