基因轉應

基因轉應（Transvection）是兩同源染色體互相配對後，一個染色體上某基因的調控序列（如強化子）促進或抑制另一染色體上該基因表現的現象，最早於1950年代由美國遺傳學家愛德華·路易斯在黑腹果蝇基因组雙胸複合群（英语：Bithorax complex）的UBX（英语：Ultrabithorax）基因發現，隨後果蠅的許多其他基因也被發現有此現象，且後續研究在老鼠、人類、植物、真菌、線蟲與昆蟲中均發現了基因轉應，顯示其可能為廣泛存在於真核生物的基因表現調控（英语：Regulation of gene expression）機制。 基因轉應一般為同源染色體彼此配對後，一個染色體的強化子等調控序列影響另一染色體基因的表現，染色體倒位可能因影響同源染色體配對而降低基因轉應效率。基因轉應也能發生在非同源染色體之間，只要兩者具有一小段同源序列而能互相配對即可，另外曾有研究發現果蠅Abd-B基因不需染色體配對即可發生基因轉應。絕緣子可能有助於維持染色體配對的結構而可促進基因轉應。性染色體上的基因轉應可能造成雌雄個體某基因表現的不同，如有研究顯示果蠅Drosophila biarmipes（瑞典语：Drosophila biarmipes）一影響翅斑的基因僅在雄性表現，原因是雌性（XX）個體中此位點有基因轉應抑制了該基因表現，雄性（XY）則因僅有一個X染色體而不發生基因轉應，故能正常表現該基因。 分子与细胞生物学主题 Lewis EB. The theory and application of a new method of detecting chromosomal rearrangements in Drosophila melanogaster. The American Naturalist. 1954, 88 (841): 225–239. doi:10.1086/281833.  Gelbart WM, Wu CT. Interactions of zeste mutations with loci exhibiting transvection effects in Drosophila melanogaster. Genetics. Oct 1982, 102 (2): 179–89. PMC 1201932 . PMID 6818101.  Duncan IW. Transvection effects in Drosophila. Annual Review of Genetics. 2002, 36: 521–56. PMID 12429702. doi:10.1146/annurev.genet.36.060402.100441.  Kennison JA, Southworth JW. Transvection in Drosophila. Adv. Genet. Advances in Genetics. 2002, 46: 399–420. ISBN 978-0-12-017646-5. PMID 11931232. doi:10.1016/S0065-2660(02)46014-2.  Pirrotta V. Transvection and chromosomal trans-interaction effects. Biochim. Biophys. Acta. July 1999, 1424 (1): M1–8. PMID 10456029. doi:10.1016/S0304-419X(99)00019-0.  McKee BD. Homologous pairing and chromosome dynamics in meiosis and mitosis. Biochim. Biophys. Acta. March 2004, 1677 (1–3): 165–80. PMID 15020057. doi:10.1016/j.bbaexp.2003.11.017.  Sandhu KS, Shi C, Sjölinder M, Zhao Z, Göndör A, Liu L, Tiwari VK, Guibert S, Emilsson L, Imreh MP, Ohlsson R. Nonallelic transvection of multiple imprinted loci is organized by the H19 imprinting control region during germline development. Genes & Development. 2009-11-15, 23 (22): 2598–603. PMC 2779760 . PMID 19933149. doi:10.1101/gad.552109.  Rassoulzadegan M, Magliano M, Cuzin F. Transvection effects involving DNA methylation during meiosis in the mouse. EMBO J. Feb 1, 2002, 21 (3): 440–50. PMC 125843 . PMID 11823436. doi:10.1093/emboj/21.3.440.  Tsai A, Singer RH, Crocker J. Transvection Goes Live-Visualizing Enhancer-Promoter Communication between Chromosomes.. Mol Cell. 2018, 70 (2): 195–196. PMID 29677489. doi:10.1016/j.molcel.2018.04.004.  Lewis, E. B. The Theory and Application of a New Method of Detecting Chromosomal Rearrangements in Drosophila melanogaster. The American Naturalist. 1954, 88 (841): 225–239. ISSN 0003-0147. doi:10.1086/281833.  R. Hopmann, D. Duncan, and I. Duncan. Transvection in the Iab-5,6,7 Region of the Bithorax Complex of Drosophila: Homology Independent Interactions in Trans. Genetics. 1995, 139 (2): 815–833.  Lim B, Heist T, Levine M, Fukaya T. Visualization of Transvection in Living Drosophila Embryos.. Mol Cell. 2018, 70 (2): 287–296.e6. PMC 6092965 . PMID 29606591. doi:10.1016/j.molcel.2018.02.029.  Galouzis CC, Prud'homme B. Transvection regulates the sex-biased expression of a fly X-linked gene.. Science. 2021, 371 (6527): 396–400. PMID 33479152. doi:10.1126/science.abc2745.