{"id":49238,"date":"2021-03-19T09:14:09","date_gmt":"2021-03-19T06:14:09","guid":{"rendered":"https:\/\/bilimvegelecek.com.tr\/?p=49238"},"modified":"2021-03-19T09:14:09","modified_gmt":"2021-03-19T06:14:09","slug":"tuberkuloz-bagisiklik-sistemimizi-nasil-yeniden-sekillendirdi","status":"publish","type":"post","link":"https:\/\/bilimvegelecek.com.tr\/index.php\/2021\/03\/19\/tuberkuloz-bagisiklik-sistemimizi-nasil-yeniden-sekillendirdi","title":{"rendered":"T\u00fcberk\u00fcloz, ba\u011f\u0131\u015f\u0131kl\u0131k sistemimizi nas\u0131l yeniden \u015fekillendirdi?"},"content":{"rendered":"

\u0130nsanl\u0131\u011f\u0131n ba\u015f\u0131na gelen salg\u0131nlar\u0131 d\u00fc\u015f\u00fcnd\u00fc\u011f\u00fcm\u00fczde akl\u0131m\u0131za ilk olarak veba, \u0130spanyol Gribi ve \u015fimdi de Covid-19 geliyor. Bu salg\u0131nlarda milyonlarca insan hayat\u0131n\u0131 kaybetti. Ancak son 2000 y\u0131l i\u00e7inde 1 milyardan fazla insan\u0131n \u00f6l\u00fcm\u00fcne sebep olan t\u00fcberk\u00fcloz (TBC) yan\u0131nda bu say\u0131lar adeta s\u00f6n\u00fck kal\u0131yor. D\u00fcnya genelinde halen y\u0131lda 1,5 milyon ki\u015fi bu hastal\u0131ktan \u00f6l\u00fcyor. T\u00fcberk\u00fclozun bu kadar \u00f6ld\u00fcr\u00fcc\u00fc olmas\u0131n\u0131n gizemi acaba nas\u0131l ve ne zamand\u0131r s\u00fcr\u00fcyor?<\/p>\n

Ara\u015ft\u0131rmac\u0131lar, insanlar\u0131 bu hastal\u0131\u011fa kar\u015f\u0131 daha duyarl\u0131 hale getirdi\u011fi d\u00fc\u015f\u00fcn\u00fclen gen varyantlar\u0131n\u0131n evrimini izleyerek son 10.000 y\u0131ldan fazla zamand\u0131r hastal\u0131ktaki ini\u015f \u00e7\u0131k\u0131\u015flar\u0131 ve bunlar\u0131n insan ba\u011f\u0131\u015f\u0131kl\u0131k sistemini nas\u0131l yeniden \u015fekillendirmi\u015f oldu\u011funu g\u00f6sterdi. Bulgular \u00f6zellikle Demir \u00c7a\u011f\u0131 Avrupas\u0131\u2019nda ya\u015fayan atalar\u0131m\u0131za aitti. Pasteur Enstit\u00fcs\u00fc\u2019nde pop\u00fclasyon geneti\u011fi \u00fczerine \u00e7al\u0131\u015fan Lluis Quintana-Murci\u2019ye g\u00f6re “Bizler, ge\u00e7mi\u015f salg\u0131nlardan -hayatta kalarak- \u00e7\u0131kabilmi\u015f atalar\u0131m\u0131z\u0131n soyundan geliyoruz”. Biliminsanlar\u0131 yay\u0131nlad\u0131klar\u0131 makalede, DNA\u2019m\u0131zda de\u011fi\u015fikliklere neden olan hangi patojen sayesinde daha diren\u00e7li hale geldi\u011fimizi g\u00f6stermeye \u00e7al\u0131\u015ft\u0131.<\/p>\n

TBC\u2019nin kayna\u011f\u0131na ait ilk izler, tar\u0131m\u0131n icad\u0131ndan hemen sonra, yani bug\u00fcnden 9000 y\u0131l \u00f6nce Orta Do\u011fu\u2019da bulunan iskeletlerde g\u00f6r\u00fclm\u00fc\u015ft\u00fc. Ancak bug\u00fcn “\u00f6ld\u00fcr\u00fcc\u00fc varyant” olarak bildi\u011fimiz Mycobacterium tuberculosis<\/em>, 2000 y\u0131l \u00f6nce insanlar\u0131n daha yo\u011fun olarak yerle\u015fik hayata ge\u00e7ip \u00f6zellikle TBC\u2019ye konak olabilecek evcille\u015ftirilmi\u015f hayvanlarla bir arada ya\u015famaya ba\u015flad\u0131klar\u0131 d\u00f6nemde kar\u015f\u0131m\u0131za \u00e7\u0131kmaktad\u0131r.<\/p>\n

\"\"
T\u00fcberk\u00fcloz, ge\u00e7ti\u011fimiz 2000 y\u0131l i\u00e7inde di\u011fer pek \u00e7ok hastal\u0131ktan daha fazla say\u0131da hastay\u0131 \u00f6ld\u00fcrm\u00fc\u015ft\u00fc. Foto\u011frafta, \u0130ngiltere parlamento binas\u0131 kar\u015f\u0131s\u0131nda dinlemekte olan hastalar da bunlardan bir ka\u00e7\u0131yd\u0131. (1936)<\/figcaption><\/figure>\n

\u0130ki y\u0131l \u00f6nce, Pasteur Enstits\u00fc\u2019nde doktora sonras\u0131 ara\u015ft\u0131rmac\u0131 olarak \u00e7al\u0131\u015fan Gaspard Kerner, TBC ile a\u011f\u0131r hastal\u0131\u011fa yakalanma riski y\u00fcksek ki\u015filerde P1104A olarak bilinen ve epeyce seyrek g\u00f6r\u00fcnen TYK2 gen varyant\u0131n\u0131n iki kopyas\u0131n\u0131n genetik olarak aktar\u0131l\u0131p aktar\u0131lmad\u0131\u011f\u0131n\u0131 bulmaya \u00e7al\u0131\u015ft\u0131. Ge\u00e7mi\u015f 10.000 y\u0131ll\u0131k s\u00fcre\u00e7te 1013 Avrupa genomunda bu varyant\u0131n s\u0131kl\u0131\u011f\u0131n\u0131 izledi\u011finde ise bu genin TBC ile nas\u0131l birlikte evrildi\u011fini g\u00f6sterebilecek alt\u0131n bir anahtar elde etmi\u015fti.<\/p>\n

Mutasyonun pop\u00fclasyon i\u00e7indeki s\u0131kl\u0131\u011f\u0131<\/strong>
\nAra\u015ft\u0131rmac\u0131lar, P1104A mutasyonunu, 8500 y\u0131l \u00f6nce Anadolu\u2019da (g\u00fcn\u00fcm\u00fczde T\u00fcrkiye’nin bulundu\u011fu b\u00f6lge) ya\u015fam\u0131\u015f olan bir \u00e7ift\u00e7inin DNA\u2019s\u0131ndan izole ettiler ve asl\u0131nda bu mutasyonun en az\u0131ndan 30.000 y\u0131ll\u0131k olabilece\u011fini hesaplad\u0131lar. Anadolulu \u00e7ift\u00e7iler ve Yamnaya \u00e7obanlar\u0131 (ge\u00e7 Tun\u00e7 \u00c7a\u011f\u0131’ndan erken Tun\u00e7 \u00c7a\u011f\u0131’na kadar var olmu\u015f, Ural Nehri, Dinyester ve G\u00fcney Bug aras\u0131ndaki b\u00f6lgelerde ya\u015fam\u0131\u015f halklar\u0131n olu\u015fturdu\u011fu bir arkeolojik k\u00fclt\u00fcr) b\u00fcy\u00fck ihtimalle bu gen varyant\u0131n\u0131 g\u00f6\u00e7lerle merkez Avrupa\u2019ya ta\u015f\u0131m\u0131\u015flard\u0131. Zaman i\u00e7inde s\u00fcren \u00e7al\u0131\u015fmalarda, varyant\u0131n s\u0131kl\u0131\u011f\u0131nda de\u011fi\u015fiklikler oldu\u011fu belirlendi. Y\u00fczde \u00fc\u00e7 kadar bir pop\u00fclasyon bu geni 5000 y\u0131l \u00f6ncesine kadar ta\u015f\u0131yordu. 3000 y\u0131l \u00f6nce yani Tun\u00e7 \u00c7a\u011f\u0131\u2019n\u0131n ortas\u0131nda ise Avrupal\u0131lar\u0131n y\u00fczde 10\u2019unda bu \u00f6zellik vard\u0131. O g\u00fcnden beri s\u0131kl\u0131k, dikey bir d\u00fc\u015f\u00fc\u015fle y\u00fczde 2.9’a kadar inmi\u015fti ve bug\u00fcn\u00fcn Avrupas\u0131\u2019nda da oran bu d\u00fczeylerdedir.<\/p>\n

\"\"Eski DNA \u00e7al\u0131\u015fmalar\u0131na g\u00f6re bu ani d\u00fc\u015f\u00fc\u015f, TBC’nin modern varyant\u0131n\u0131n ortaya \u00e7\u0131kt\u0131\u011f\u0131 zamana denk geliyor. Quintana-Murci ve ekibi, bir bilgisayar sim\u00fclasyonuyla, pop\u00fclasyon geni\u015fli\u011finin ve g\u00f6\u00e7\u00fcn gen s\u0131kl\u0131\u011f\u0131n\u0131 nas\u0131l etkileyebilece\u011fini belirlemeye \u00e7al\u0131\u015ft\u0131lar. Sonu\u00e7lar, TBC\u2019nin, yakla\u015f\u0131k 2000 y\u0131l \u00f6nce Tun\u00e7 \u00c7a\u011f\u0131’n\u0131n sona ermesinden sonra hayatta kalabilenlerden, varyant\u0131n iki kopyas\u0131na sahip olanlar\u0131n be\u015fte birini \u00f6ld\u00fcrd\u00fc\u011f\u00fcn\u00fc veya ciddi \u015fekilde hasta etti\u011fine i\u015faret ediyordu. Sonu\u00e7 olarak, do\u011fal seleksiyon, \u00f6l\u00fcmc\u00fcl gen varyant\u0131n\u0131 d\u00fc\u015f\u00fck seviyelere \u00e7ekmek i\u00e7in g\u00fc\u00e7l\u00fc ve h\u0131zl\u0131 bir \u015fekilde hareket etmi\u015fti. Sonu\u00e7lar The American Journal of Human Genetics<\/em>‘de yay\u0131mland\u0131.<\/p>\n

Quentina-Murci\u2019ye g\u00f6re “salg\u0131n hastal\u0131klar insano\u011flunun y\u00fczle\u015fmek zorunda kald\u0131\u011f\u0131 en g\u00fc\u00e7l\u00fc evrimsel bask\u0131lar\u0131 yarat\u0131yor”. Gen varyant\u0131n\u0131n iki kopyas\u0131n\u0131 da ta\u015f\u0131yorsan\u0131z TBC\u2019den uzak durmak ya\u015famsal \u00f6nemde olacakt\u0131r.<\/p>\n

Ara\u015ft\u0131rmac\u0131lar, insanlarda se\u00e7ilim i\u00e7in ge\u00e7en zamanla, g\u00fcn\u00fcm\u00fczde TBC’nin ortaya \u00e7\u0131kmas\u0131 aras\u0131ndaki zamanlaman\u0131n m\u00fckemmel bir \u015fekilde uydu\u011funu s\u00f6yl\u00fcyor. Max Planck Enstit\u00fcs\u00fc Evrimsel Antropoloji B\u00f6l\u00fcm\u00fc paleontologlar\u0131na g\u00f6re \u201dbenzer sonu\u00e7lar veren iki farkl\u0131 veri \u00e7izgisini g\u00f6rmek harika ve heyecan verici\u201d.<\/p>\n

Patojenlerle birlikte ba\u011f\u0131\u015f\u0131kl\u0131k sistemimiz nas\u0131l evrimle\u015fti?<\/strong>
\nUK gen bankas\u0131 ve t\u00fcm d\u00fcnyadan gelen di\u011fer eski DNA \u00f6rnekleri bir araya geldi\u011finde izi s\u00fcr\u00fclen varyant s\u0131kl\u0131klar\u0131 daha net belirlenebilecek ve b\u00f6ylece spesifik patojenlerle birlikte ba\u011f\u0131\u015f\u0131kl\u0131k sistemimizin nas\u0131l evrildi\u011fi a\u00e7\u0131kl\u0131k kazanabilecektir.<\/p>\n

Ne var ki, ara\u015ft\u0131rmac\u0131lara g\u00f6re bu aralar P1104A varyant\u0131n\u0131n d\u00fcnya \u00e7ap\u0131nda nas\u0131l bir geni\u015flikte yay\u0131ld\u0131\u011f\u0131n\u0131 \u00f6\u011frenmek acildir. \u00c7\u00fcnk\u00fc \u00f6rne\u011fin TBC\u2019nin neredeyse salg\u0131nlarla neden oldu\u011fu Hindistan, Endonezya, \u00c7in ve Afrika\u2019n\u0131n bir k\u0131sm\u0131nda bu varyant \u00e7ok nadirken; \u0130ngiltere\u2019de 600 ki\u015fiden birinde varyant\u0131n iki kopyas\u0131n\u0131 ta\u015f\u0131yan bireyler oldu\u011fu g\u00f6sterilmi\u015ftir. TBC ortaya \u00e7\u0131kt\u0131\u011f\u0131nda bu bireylerde a\u011f\u0131r hastal\u0131k veya \u00f6l\u00fcm riski daha \u00e7ok artacakt\u0131r.<\/p>\n

Kaynaklar: <\/strong><\/p>\n

– https:\/\/www.sciencemag.org\/news\/2021\/03\/how-tuberculosis-reshaped-our-immune-systems<\/p>\n

– tr.wikipedia.org\/<\/p>\n","protected":false},"excerpt":{"rendered":"

\u0130nsanl\u0131\u011f\u0131n ba\u015f\u0131na gelen salg\u0131nlar\u0131 d\u00fc\u015f\u00fcnd\u00fc\u011f\u00fcm\u00fczde akl\u0131m\u0131za ilk olarak veba, \u0130spanyol Gribi ve \u015fimdi de Covid-19 geliyor. Bu salg\u0131nlarda milyonlarca insan hayat\u0131n\u0131 kaybetti. Ancak son 2000 y\u0131l i\u00e7inde 1 milyardan fazla insan\u0131n \u00f6l\u00fcm\u00fcne sebep olan t\u00fcberk\u00fcloz (TBC) yan\u0131nda bu say\u0131lar adeta s\u00f6n\u00fck kal\u0131yor. D\u00fcnya genelinde halen y\u0131lda 1,5 milyon ki\u015fi bu hastal\u0131ktan \u00f6l\u00fcyor. T\u00fcberk\u00fclozun bu kadar […]<\/p>\n","protected":false},"author":42,"featured_media":49240,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[19,21,3729,33],"tags":[2413,200,431,5764,6558],"class_list":["post-49238","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-bilim-gundemi","category-biyoloji","category-genetik","category-saglik-bilimleri","tag-bagisiklik-sistemi","tag-evrim","tag-gen","tag-salgin","tag-tuberkuloz"],"acf":[],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t