ژنهايي از پستوخانه

Genes from The Junkyard

ﺑﺮ ﺧﻼف دﻳﺪﮔﺎه ﻛﻼﺳﻴﻚ ﻛﻪ ژﻧﻬﺎي ﺟﺪﻳﺪ ﺻﺮﻓﺎً از ژﻧﻬﺎي ﻗﺒﻠﻲ ﺗﻜﺎﻣﻞ ﻣﻲﻳﺎﺑﻨﺪ، ﻛﺸﻔﻴﺎت ﺟﺪﻳﺪ ﻧﺸﺎن ﻣﻲدﻫﺪ ﻛﻪ ﻣﻨﺒﻊ ژﻧﻬﺎي ﺟﺪﻳﺪ ﻣﻲﺗﻮاﻧﺪ ﺑﻪ ﺷﻜﻞ De novo از ﺗﻮاﻟﻲ ﻫﺎي ﻏﻴﺮرﻣﺰﮔﺬار ﻫﻢ ﺑﻪ وﺟﻮد آﻳﻨﺪ. ﺑﺮآوردﻫﺎ ﻧﺸﺎن ﻣﻲدﻫﻨﺪ ﻛﻪ ﺣﺪود 10 درﺻﺪ ژﻧﻬﺎ از ﻃﺮﻳﻖ De novo ﺳﺎﺧﺘﻪ ﻣﻲﺷﻮﻧﺪ. اﻳﻦ ﻳﺎﻓﺘﻪﻫﺎ دﻳﺪﮔﺎه ﻣﺮﺳﻮم ﺗﻜﺎﻣﻞ ژﻧﻬﺎ را ﺗﻮﺳﻌﻪ ﻣﻲﺑﺨﺸﺪ و ﻧﺸﺎن ﻣﻲدﻫﺪ ﻛﻪ ﺗﺸﻜﻴﻞ ژﻧﻬﺎي ﺟﺪﻳﺪ در ﻃﻮل ﺗﻜﺎﻣﻞ اﻧﻌﻄﺎفﭘﺬﻳﺮﺗﺮ از آن اﺳﺖ ﻛﻪ ﻗﺒﻼً ﺗﺼﻮر ﻣﻲﺷﺪ. اﻳﻨﻜﻪ ژﻧﻬﺎي ﺟﺪﻳﺪ ﻣﻲﺗﻮاﻧﻨﺪ از ﺗﻮاﻟﻲﻫﺎي ﺗﻜﺮاري، زﻣﺎﻧﻲ ﻣﻮﺳﻮم ﺑﻪ Junk DNA ﭘﺪﻳﺪ آﻳﻨﺪ ﻧﻘﺶ ﺗﺎزهاي ﺑﺮاي اﻳﻦ ﺗﻮاﻟﻲﻫﺎي ﻏﻴﺮرﻣﺰﮔﺬار ﺗﺄﻳﻴﺪ ﻣﻲﻛﻨﺪ. اﻳﺠﺎد ژﻧﻬﺎي ﺟﺪﻳﺪ از اﻳﻦ راه ﮔﻮﻳﻲ ﻣﻮﺟﻮدات ﺣﺎﻣﻞ آﻧﻬﺎ را ﺑﺮاي ﺳﺎزﮔﺎري ﺑﺎ ﻣﺤﻴﻂ ﻛﺎرآﺗﺮ ﻣﻲﺳﺎزد و ﻧﺸﺎن ﻣﻲدﻫﺪ ﻛﻪ ژﻧﮕﺎن ﻣﻮﺟﻮدات ﺗﺎ ﭼﻪ اﻧﺪازه ﭘﻮﻳﺎﺳﺖ.

In the depths of winter, water temperatures in the ice-covered Arctic Ocean can sink below zero. That’s cold enough to freeze many fish, but the conditions don’t trouble the cod. A protein in its blood and tissues binds to tiny ice crystals and stops them from growing. Where codfish got this talent was a puzzle that evolutionary biologist Helle Tessand Baalsrud wanted to solve. She and her team at the University of Oslo searched the genomes of the Atlantic cod (Gadus morhua) and several of its closest relatives, thinking they would track down the cousins of the antifreeze gene. None showed up. Baalsrud, who at the time was a new parent, worried that her lack of sleep was causing her to miss something obvious.