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‫ﺗﻌﺎﺩﻝ ﮊﻧﻲ ﺩﺭ ﻣﮕﺲ ﺳﺮﻛﻪ‬ ‫ﻛﺎﻟﻮﻳﻦ ﺑﺮﻳﭻ ﺩﺭ ﻛﺎﺭﻫﺎﻱ ﺧﻮﺩﺭﻭﻱ ﻣﮕﺲ ﺳﺮﻛﻪ ﻳﻚ ﻣﺎﺩﻩ ﻱ ﺗﺮﻳﭙﻠﻮﺋﻴﺪ ) ‪ (3n‬ﺭﺍ ﺑﺎ ﻳﻚ ﻧﺮ ﻋﺎﺩﻱ ﺁﻣﻴـﺰﺵ ﺩﺍﺩ ﻭ‬ ‫ﺗﺮﻛﻴﺒﺎﺕ ﻣﺘﻨﻮﻋﻲ ﺍﺯ ﻛﺮﻭﻣﻮﺯﻭﻡ ﻫﺎﻱ ﺁﺗﻮﺯﻭﻡ ﻭ ﺟﻨﺴﻲ ﺭﺍ ﺩﺭ ﺑﻴﻦ ﺯﺍﺩﻩ ﻫﺎ ﻣﺸﺎﻫﺪ ﻛﺮﺩ‪.‬‬ ‫ﺑﺮﻳﺞ ﺩﺭ ﺳﺎﻝ ‪ 1992‬ﭘﻴﺸﻨﻬﺎﺩ ﻛﺮﺩ ﻛﻪ ﺟﻨﺴﻴﺖ ﺩﺭ ﻣﮕﺲ ﺳﺮﻛﻪ ﺑﻮﺳﻴﻠﻪ ﻱ ﺗﻌﺎﺩﻝ ﻳﺎ ﻧﺴﺒﺖ ﺁﻟﻞ ﻫﺎﻱ ﺁﺗﻮﺯﻭﻡ ﻛﻪ‬ ‫ﺑﻪ ﻧﺮ ﺑﻮﺩﻥ ﻛﻤﻚ ﻣﻲ ﻛﻨﻨﺪ ﻭ ﺁﻟﻞ ﻫﺎﻱ ﺭﻭﻱ ﻛﺮﻭﻣﻮﺯﻭﻡ ‪ X‬ﻛﻪ ﺑﻪ ﻣﺎﺩﻩ ﺑﻮﺩﻥ ﻛﻤﻚ ﻣﻲ ﻛﻨﻨﺪ ﺗﻌﻴﻴﻦ ﻣﻲ ﺷـﻮﺩ ﺍﻭ‬ ‫ﻧﺴﺒﺖ ﻛﺮﻭﻣﻮﺯﻭﻡ ﻫﺎﻱ ‪ X‬ﺑﻪ ﻣﺠﻤﻮﻋﻪ ﻫﺎﻱ ﻛﺮﻭﻣﻮﺯﻭﻡ ﻫﺎﻱ ﺁﺗﻮﺯﻭﻡ ﺭﺍ ﻣﺤﺎﺳﺒﻪ ﻛﺮﺩ ﺗﺎ ﺑﺒﻴﻨﻴﺪ ﺁﻳﺎ ﺍﻳﻦ ﻧﺴﺒﺖ ﻫـﺎ‬ ‫ﻣﻲ ﺗﻮﺍﻧﻨﺪ ﺟﻨﺴﻴﺖ ﻣﮕﺲ ﻫﺎﻱ ﺳﺮﻛﻪ ﺭﺍ ﭘﻴﺶ ﺑﻴﻨﻲ ﻛﻨﻨﺪﻩ ﻳﻚ ﺳـﺮﻱ ﺁﺗـﻮﺯﻭﻣﻲ ﺩﺭ ﻣﮕـﺲ ﺳـﺮﻛﻪ ﺷـﺎﻣﻞ ‪3‬‬ ‫ﻛﺮﻭﻣﻮﺯﻭﻡ ﺍﺳﺖ ﺟﺪﻭﻝ ‪ 1‬ﻛﻪ ﺑﻴﺎﻥ ﻛﻨﻨﺪﻩ ﻱ ﻧﺘﺎﻳﺞ ﺍﺳﺖ ﻧﺸﺎﻥ ﻣﻲ ﺩﻫﺪ ﻛﻪ ﭘﻴﺶ ﺑﻴﻨﻲ ﺑﺮﻳﺞ ﺩﺭ ﻣﻮﺭﺩ ﻧﺴﺒﺖ ﮊﻧﻲ‬ ‫ﺑﺮﺍﻱ ﺗﻌﻴﻴﻦ ﺟﻨﺴﻴﺖ ﺩﺭﺳﺖ ﺍﺳﺖ‪ .‬ﻭﻗﺘﻲ ﻛﻪ ﻧﺴﺒﺖ ‪ ) X : A‬ﺗﻌﺪﺍﺩ ﻛﺮﻭﻣﻮﺯﻭﻡ ﻫﺎﻱ ‪ X‬ﺑﻪ ﺗﻌـﺪﺍﺩ ﺳـﺮﻱ ﻫـﺎﻱ‬ ‫ﺁﺗﻮﺯﻭﻣﻲ ‪ ( A‬ﺑﺮﺍﺑﺮ ‪ 1‬ﺑﺎﺷﺪ ﻫﻤﺎﻧﻄﻮﺭ ﻛﻪ ﺩﺭ ﻳﻚ ﻣﺎﺩﻩ ﻱ ﻋﺎﺩﻱ ﺍﻳﻦ ﮔﻮﻧﻪ ﺍﺳﺖ ﻳﺎ ﻭﻗﺘﻲ ﻛﻪ ﺍﻳﻦ ﻧـﺴﺒﺖ ﺑـﻴﺶ ﺍﺯ‬ ‫ﻳﻚ ﺑﺎﺷﺪ ﺟﺎﻧﺪﺍﺭ ﻣﻮﺭﺩ ﻣﻄﺎﻟﻌﻪ ﻱ ﻣﺎ ﻣﺎﺩﻩ ﺍﺳﺖ ﻭ ﻭﻗﺘﻲ ﻛﻪ ﺍﻳﻦ ﻧﺴﺒﺖ ﻣﺜﻞ ﻳﻚ ﻧﺮ ﻋﺎﺩﻱ ‪ 0/5‬ﺑﺎﺷﺪ ﻳﺎ ﻛﻤﺘﺮ ﺍﺯ ﺁﻥ‬ ‫ﺑﺎﺷﺪ ﺟﺎﻧﺪﺍﺭ ﻣﻮﺭﺩ ﻣﻄﺎﻟﻌﻪ ﻧﺮ ﺍﺳﺖ‪ .‬ﺍﮔﺮ ﺍﻳﻦ ﻧﺴﺒﺖ ‪ 0/67‬ﺑﺎﺷﺪ ﺟﺎﻧﺪﺍﺭ ﻳﻚ ‪ int ersex‬ﺍﺳـﺖ ) ‪ Metamale‬ﺑـﺎ‬ ‫‪X‬‬ ‫‪X‬‬ ‫ﻧﺴﺒﺖ ‪ Metafemal, = 0 / 33‬ﺑﺎ ﻧﺴﺒﺖ ‪= 1 / 5‬‬ ‫‪A‬‬ ‫‪A‬‬

‫ﻣﻌﻤﻮﻻﹰ ﺧﻴﻠﻲ ﺿﻌﻴﻒ ﻭ ﻧﺎﺯﺍ ﻫﺴﺘﻨﺪ‪.‬‬

‫ﻋﻼﻭﻩ ﺑﺮ ﺍﻳﻦ ﻋﻮﺍﻣﻠﻲ ﻛﻪ ﺗﺎ ﺑﻪ ﺣﺎﻝ ﺑﻪ ﻋﻨﻮﺍﻥ ﻋﻮﺍﻣﻞ ﻣﻮﺛﺮ ﺑﺮ ﺗﻌﻴﻴﻦ ﺟﻨﺴﻴﺖ ﺷﻨﺎﺧﺘﻴﻢ ﻣﺤﻴﻂ ﻭ ﺁﻟﻞ ﻫﺎﻳﻲ‬ ‫ﻛﻪ ﺩﺭ ﭼﻨﺪﻳﻦ ‪ Locus‬ﻗﺮﺍﺭ ﺩﺍﺭﻧﺪ ﻫﻢ ﺭﻭﻱ ﺗﻌﻴﻴﻦ ﺟﻨﺴﻴﺖ ﻣﮕﺲ ﺗﺎﺛﻴﺮ ﺩﺍﺭﻧﺪ ﺑﻪ ﻋﻨﻮﺍﻥ ﻣﺜﺎﻝ ﻣﮕﺲ ‪int ersex‬‬


‫‪X‬‬ ‫ﻛﻪ ﻧﺴﺒﺖ‬ ‫‪A‬‬

‫ﺑﺮﺍﻱ ﺁﻥ ‪ 0/67‬ﺍﺳﺖ ﺩﺭ ﺩﻣﺎﻫﺎﻱ ﺑﺎﻻﺗﺮ ﺑﻪ ﻃﺮﻑ ﺍﻧﺘﻬﺎﻱ ﻣﺎﺩﻩ ﻱ ﻃﻴﻒ ‪ int ersex‬ﺭﺷﺪ ﻣﻲ ﻛﻨـﺪ ﻭ‬

‫ﺩﺭ ﺩﻣﺎﻫﺎﻱ ﭘﺎﻳﻴﻦ ﺑﻪ ﺍﻧﺘﻬﺎﻱ ﻧﺮ ﺍﻳﻦ ﻃﻴﻒ ﻧﺰﺩﻳﻚ ﻣﻲ ﺷﻮﺩ ﺑﻪ ﻫﻤﻴﻦ ﺗﺮﺗﻴﺐ ﺁﻟﻞ ﻫﺎﻱ ﺁﺗﻮﻣﻮﺯﻭﻣﻲ ﻫﻢ ﻣﻲ ﺗﻮﺍﻧﻨـﺪ‬ ‫ﺭﻭﻱ ﺟﻨﺴﻴﺖ ﻣﻮﺛﺮ ﺑﺎﺷﻨﺪ ﻳﻚ ﺁﻟﻞ ﻣﻐﻠﻮﺏ ﺑﻪ ﻧﺎﻡ )‪ doublesex(dsx‬ﻧﺮﻫﺎ ﻭ ﻣﺎﺩﻩ ﻫﺎ ﺭﺍ ﺑـﻪ ‪ int ersex‬ﺗﺒـﺪﻳﻞ‬ ‫ﻣﻲﻛﻨﺪ‪.‬‬ ‫ﺁﻟﻞ ﻣﻐﻠﻮﺏ ﺩﻳﮕﺮﻱ ﺑﻪ ﻧـﺎﻡ ) ‪ TransForme r (tra‬ﻭﺟـﻮﺩ ﺩﺍﺭﺩ ﻛـﻪ ﺟﺎﻧـﺪﺍﺭﺍﻧﻲ ﻛـﻪ ﺍﺯ ﻟﺤـﺎﻅ ﻧـﺴﺒﺖ‬ ‫ﻛﺮﻭﻣﻮﺯﻭﻣﻲ ﻣﺎﺩﻩ ﺍﻧﺪ ﺭﺍ ﺑﻪ ﻣﺮﺩﺍﻥ ﻋﻘﻴﻢ ﺗﺒﺪﻳﻞ ﻣﻲ ﻛﻨﺪ‪ .‬ﭘﺲ ﭼﻬﺎﺭﭼﻮﺑﻲ ﻛﻪ ﻧﻈﺮﻳـﻪ ﻱ ﺗﻌـﺎﺩﻟﻲ ﮊﻧـﻲ ﺑـﺮﻳﺞ ﺩﺭ‬ ‫ﺍﺧﺘﻴﺎﺭ ﻣﺎ ﻗﺮﺍﺭ ﻣﻲ ﺩﻫﺪ ﻣﻤﻜﻦ ﺍﺳﺖ ﺑﻪ ﻭﺳﻴﻠﻪ ﻱ ﻣﺤﻴﻂ ﻭ ﻫﻤﭽﻨﻴﻦ ﺁﻟﻞ ﻫﺎﻱ ﺁﺗﻮﺯﻭﻣﻲ ﺗﺤﺖ ﺗﺎﺛﻴﺮ ﻗـﺮﺍﺭ ﮔﻴـﺮﺩ‪.‬‬ ‫ﻳﻚ ﮊﻥ ﺗﻐﻴﻴﺮ ﺟﻨﺴﻴﺖ )‪ ( sex − switch gene‬ﻛﺸﻒ ﺷﺪﻩ ﺍﺳﺖ ﻛﻪ ﺑﻪ ﻧﻈﺮ ﻣﻲ ﺭﺳﺪ ﺗﻜﺎﻣﻞ ﻣﺎﺩﻩ ﺭﺍ ﺑﻪ ﭘـﻴﺶ‬ ‫ﻣﻲ ﺑﺮﺩ‪ .‬ﺍﻳﻦ ﮊﻥ )‪ sex − lethal (SXL‬ﺍﺳﺖ‪ ،‬ﺭﻭﻱ ﻛﺮﻭﻣـﻮﺯﻭﻡ ‪ X‬ﻗـﺮﺍﺭ ﺩﺍﺭﺩ ﻭ ﺩﻭ ﻭﺿـﻌﻴﺖ ﻓﻌﺎﻟﻴـﺖ ﺩﺍﺭﺩ ﺩﺭ‬ ‫ﻭﺿﻌﻴﺖ ﺭﻭﺷﻦ ﺗﻜﺎﻣﻞ ﻣﺎﺩﻩ ﺭﺍ ﺑﻪ ﭘﻴﺶ ﻣﻲ ﺑﺮﺩ ﻭ ﻭﺿﻌﻴﺖ ﺧﺎﻣﻮﺵ ﻣﺮﺩﺍﻧﮕﻲ ﺭﺍ ﺑﻪ ﺩﻧﺒـﺎﻝ ﺩﺍﺭﺩ‪ .‬ﺍﻳـﻦ ﮊﻥ ﺗﻐﻴﻴـﺮ‬ ‫ﺟﻨﺴﻴﺖ ﺑﻪ ﻭﺳﻴﻠﻪ ﻱ ﮊﻥ ﻫﺎﻱ ﺩﻳﮕﺮﻱ ﻛﻪ ﺭﻭﻱ ﻛﺮﻭﻣﻮﺯﻭﻡ ‪ X‬ﻳﺎ ﻛﺮﻭﻣﻮﺯﻭﻡ ﻫﺎﻱ ﺁﺗﻮﺯﻭﻡ ﻗﺮﺍﺭ ﺩﺍﺭﻧﺪ ﺗﻨﻈـﻴﻢ ﻣـﻲ‬ ‫ﺷﻮﺩ ﮊﻥ ﻫﺎﻱ ﺭﻭﻱ ﻛﺮﻭﻣﻮﺯﻭﻡ ‪ X‬ﻛﻪ ﮊﻥ ‪ SXL‬ﺭﺍ ﺑﻪ ﻭﺿﻌﻴﺖ ﺭﻭﺷﻦ ﻣﻲ ﺑﺮﻧﺪ‪.‬‬ ‫‪X‬‬ ‫" ﺍﻟﻤﺎﻥ ﺻﻮﺭﺕ ﻛﺴﺮ " ﻧﺎﻣﻴﺪﻩ ﻣﻲ ﺷﻮﺩ ﭼﻮﻥ ﺑﺮ ﺭﻭﻱ ﺻﻮﺭﺕ ﻛﺴﺮ‬ ‫‪A‬‬

‫ﺗﺎﺛﻴﺮ ﻣﻲ ﮔﺬﺍﺭﻧﺪ‪.‬‬

‫ﮊﻥ ﻫﺎﻱ ﺭﻭﻱ ﻛﺮﻭﻣﻮﺯﻭﻡ ﻫﺎﻱ ﺁﺗﻮﺯﻭﻡ ﻛﻪ ﺑﺎ ﺗﻨﻈﻴﻢ ﻋﻤﻞ ‪ SXL‬ﺁﻥ ﺭﺍ ﺑﻪ ﺳﻤﺖ ﺣﺎﻟﺖ ﺧﺎﻣﻮﺵ ﻣﻲ ﺑـﺮﺩ "‬ ‫‪X‬‬ ‫ﺍﻟﻤﺎﻥ ﻫﺎﻱ ﻣﺨﺮﺝ ﻛﺴﺮ " ﻧﺎﻣﻴﺪﻩ ﻣﻲ ﺷﻮﻧﺪ ﭼﻮﻥ ﺭﻭﻱ ﻣﺨﺮﺝ ﻛﺴﺮ ﺗﻌﺎﺩﻝ ﮊﻧﻲ ‪  ‬ﺗﺎﺛﻴﺮ ﻣﻲ ﮔﺬﺍﺭﻧﺪ‪.‬‬ ‫‪ A‬‬ ‫ﺳﻪ " ﺍﻟﻤﺎﻥ ﺻﻮﺭﺕ ﻛﺴﺮ "ﻛﺸﻒ ﺷﺪﻩ ﺍﺳﺖ ﺗﺤﻘﻴﻖ ﺭﻭﻱ ﺁﻥ ﻫﺎ ﺑﺎﻋﺚ ﺷﺪﻩ ﺩﺍﻧﺸﻤﻨﺪﺍﻥ ﭘﻴﺶ ﺑﻴﻨﻲ ﻛﻨﻨـﺪ‬


‫ﻛﻪ ﺷﻤﺎﺭ ﺍﻟﻤﺎﻥ ﻫﺎﻱ ﺻﻮﺭﺕ ﻛﺴﺮ ﻧﺴﺒﺘﺎﹰ ﻛﻮﭼﻚ ﺍﺳﺖ ﺑﻨﺎﺑﺮﺍﻳﻦ ﺗﻨﻬﺎ ﺗﻌﺪﺍﺩ ﻛﻤﻲ ﺍﺯ ﮊﻥ ﻫﺎ ﺩﺭ ﺗﻨﻈـﻴﻢ ﮊﻥ ﺗﻐﻴﻴـﺮ‬ ‫ﺟﻨﺴﻴﺖ ﻧﻘﺶ ﺩﺍﺭﻧﺪ‪ .‬ﺍﮔﺮ ﭼﻪ ﻣﻜﺎﻧﻴﺰﻡ ﻋﻤﻞ ‪ SXL‬ﻭ ﮊﻥ ﻫﺎﻱ ﺗﻨﻈﻴﻢ ﻛﻨﻨﺪﻩ ﻱ ﺁﻥ ﻧﺎﺷـﻨﺎﺧﺘﻪ ﺍﺳـﺖ ﻣـﻲ ﺗـﻮﺍﻥ‬ ‫‪X‬‬ ‫ﻓﻬﻤﻴﺪ ﻛﻪ ﺗﺌﻮﺭﻱ ﻧﺴﺒﺖ ﮊﻧﻲ ‪  ‬ﺑﺮﻳﺞ ﻧﺘﻴﺠﻪ ﻱ ﺗﻌﺪﺍﺩ ﻛﻤﻲ ﺍﺯ ﮊﻥ ﻫﺎﻱ ﻛﺮﻭﻣـﻮﺯﻭﻡ ‪ X‬ﻭ ﻛﺮﻭﻣـﻮﺯﻭﻡ ﻫـﺎﻱ‬ ‫‪ A‬‬ ‫ﺁﺗﻮﺯﻭﻡ ﺍﺳﺖ‪.‬‬

‫)ﺟﺪﻭﻝ ‪( 1‬‬

‫ﺩﺍﺩﻩ ﻫﺎﻳﻲ ﻛﻪ ﺍﺯ ﺗﺌﻮﺭﻱ ﺑﺮﻳﺞ ﺩﺭ ﻣﻮﺭﺩ ﺗﻌﻴﻴﻦ ﺟﻨﺴﻴﺖ ﺑﻮﺳﻴﻠﻪ ﻱ ﻧﺴﺒﺖ ﮊﻧﻲ ﺩﺭ ﻣﮕﺲ ﺳﺮﻛﻪ ﺣﻤﺎﻳﺖ ﻣﻲ ﻛﻨﻨﺪ‪.‬‬


(David Page)

(Peter Goodfellow)


‫)‪(RobinLovell- Badge‬‬

‫ﻣﻮﺵ ﻧﺮ ﻃﺒﻴﻌﻲ ) ﭼﭗ ( ﻭ ﻣﻮﺵ ﻣﺎﺩﻩ ‪ ) littermate‬ﺭﺍﺳﺖ ( ﻛﻪ ﮊﻥ‪ SRY‬ﺭﺍ ﺩﺍﺭﺩ‪ .‬ﻫﺮ ﺩﻭ ﻣﻮﺵ‪ ،‬ﻇﺎﻫﺮ ﻣﻮﺵ ﻧﺮ ﺭﺍ ﺩﺍﺭﻧﺪ‪( .‬‬

تعادل ژنی در مگس سرکه  
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