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A metafemale (or superfemale) is a low viability ''Drosophila'' fruit fly with a female phenotype in which the ratio of X chromosomes to sets of autosomes (A) exceeds 1.0.〔 genic balance: a mechanism of sex determination, originally discovered in ''Drosophila'', that depends on the ratio of X chromosomes to sets of autosomes (A). Males develop when the X/A ratio is 0.5 or less, females develop when the X/A ratio is 1.0 or greater, an intersex develops when the ratio is between 0.5 and 1.0. ''See'' Appendix C, 1925, Bridges; metafemales, metamales, sex determination. metafemale: in ''Drosophila'', a female phenotype of relatively low viability in which the ratio of X chromosomes to sets of autosomes exceeds 1.0, previously called a ''superfemale''. ''See'' intersex, metamale. metamale: in ''Drosophila'', a poorly viabile male characterized by cells containing one X and three sets of autosomes, previously called a ''supermale''. ''See'' intersex, metafemale. superfemale: metafemale (''q.v.''). supermale: metamale (''q.v.'').〕 For example: a fly with one X chromosome and two sets of autosomes is a normal male, a fly with two X chromosomes and two sets of autosomes is a normal female, and a fly with three X chromosomes and two sets of autosomes (or four X chromosomes and three sets of autosomes) is a metafemale. American geneticist Calvin Bridges, who discovered the genic balance sex-determination system in ''Drosophila'' in 1921, used the terms "superfemale" and "supermale". German-American geneticist Curt Stern proposed the alternate terms "metafemale" and "metamale" in 1959. == References == 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Metafemale」の詳細全文を読む スポンサード リンク
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