Biology:Pair-rule gene

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Short description: Gene involved in the development of segmented embryos of insects
Expression of the pair-rule genes even-skipped and fushi tarazu in alternating bands in the Drosophila early embryo. Each band corresponds to one parasegment.

A pair-rule gene is a type of gene involved in the development of the segmented embryos of insects. Pair-rule genes are expressed as a result of differing concentrations of gap gene proteins, which encode transcription factors controlling pair-rule gene expression.[1][2] Pair-rule genes are defined by the effect of a mutation in that gene, which causes the loss of the normal developmental pattern in alternating segments.

Pair-rule genes were first described by Christiane Nüsslein-Volhard and Eric Wieschaus in 1980.[3] They used a genetic screen to identify genes required for embryonic development in the fruit fly Drosophila melanogaster. In normal unmutated Drosophila, each segment produces bristles called denticles in a band arranged on the side of the segment closer to the head (the anterior). They found five genes – even-skipped, hairy, odd-skipped, paired and runt – where mutations caused the deletion of a particular region of every alternate segment. For example, in even-skipped, the denticle bands of alternate segments are missing, which results in an embryo having half the number of denticle bands. Later work identified more pair-rule genes in the Drosophila early embryo – fushi tarazu, odd-paired and sloppy paired.[4]

Once the pair-rule genes had been identified at the molecular level it was found that each gene is expressed in alternate parasegments – regions in the embryo that are closely related to segments, but are slightly out of register.[5][6][7][8] Each parasegment includes the posterior part of one (future) segment, and an anterior part of the next (more posterior) segment. The bands of expression of the pair-rule genes correspond to the regions missing in the mutant. The expression of the pair-rule genes in bands is dependent both upon direct regulation by the gap genes [9] and on regulatory interactions between the pair-rule genes themselves.[10]

See also

References

  1. ↑ Gilbert, SF (2000). Developmental Biology (6th ed.). Sunderland (MA): Sinauer Associates. pp. The Origins of Anterior–Posterior Polarity. https://www.ncbi.nlm.nih.gov/books/NBK10039/. Retrieved 23 October 2015. 
  2. ↑ "Segmentation Genes in Drosophila Development: Pair Rule, Segment Polarity & Gap Genes". http://study.com/academy/lesson/segmentation-genes-in-drosophila-development-pair-rule-segment-polarity-gap-genes.html. 
  3. ↑ "Mutations affecting segment number and polarity in Drosophila". Nature 287 (5785): 795–801. October 1980. doi:10.1038/287795a0. PMID 6776413. Bibcode: 1980Natur.287..795N. 
  4. ↑ "Analysis of larval segmentation in lethal genotypes associated with the antennapedia gene complex in Drosophila melanogaster". Dev. Biol. 81 (1): 51–64. January 1981. doi:10.1016/0012-1606(81)90347-X. PMID 6780397. 
  5. ↑ "Spatial distribution of transcripts from the segmentation gene fushi tarazu during Drosophila embryonic development". Cell 37 (3): 833–41. July 1984. doi:10.1016/0092-8674(84)90418-5. PMID 6430568. 
  6. ↑ Ingham, P. W.; K. R. Howard; D. Ish-Horowicz (1985). "Transcription pattern of the Drosophila segmentation gene hairy". Nature 318 (6045): 439–445. doi:10.1038/318439a0. Bibcode: 1985Natur.318..439I. 
  7. ↑ "Isolation, structure, and expression of even-skipped: a second pair-rule gene of Drosophila containing a homeo box". Cell 47 (5): 721–34. December 1986. doi:10.1016/0092-8674(86)90515-5. PMID 2877745. 
  8. ↑ "Borders of parasegments in Drosophila embryos are delimited by the fushi tarazu and even-skipped genes". Nature 328 (6129): 440–2. 1987. doi:10.1038/328440a0. PMID 2886916. 
  9. ↑ Ingham, P. W.; Ish-Horowicz, D.; Howard, KR (1986). "Correlative changes in homoeotic and segmentation gene expression in Krüppel mutant embryos of Drosophila". The EMBO Journal 5 (7): 1659–65. doi:10.1002/j.1460-2075.1986.tb04409.x. PMID 16453692. 
  10. ↑ Howard K .; Ingham P (1986). "Regulatory interactions between the segmentation genes fushi tarazu, hairy, and engrailed in the Drosophila blastoderm". Cell 44 (6): 949–957. doi:10.1016/0092-8674(86)90018-8. PMID 3955654. 

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