{"id":26898,"date":"2014-03-01T17:19:52","date_gmt":"2014-03-01T15:19:52","guid":{"rendered":"https:\/\/bilimvegelecek.com.tr\/?p=26898"},"modified":"2018-06-12T17:24:10","modified_gmt":"2018-06-12T14:24:10","slug":"ates-cemberinin-icine-yolculuk","status":"publish","type":"post","link":"https:\/\/bilimvegelecek.com.tr\/index.php\/2014\/03\/01\/ates-cemberinin-icine-yolculuk","title":{"rendered":"Ate\u015f \u00c7emberi\u2019nin i\u00e7ine yolculuk"},"content":{"rendered":"

Efsanevi Amerikan country m\u00fczisyeni Johnny Cash, hit \u015fark\u0131s\u0131 Ring of Fire<\/em>\u2019da a\u015fk\u0131 bir ate\u015f \u00e7emberinin i\u00e7inde olmaya benzetir: Yanan bir ate\u015f \u00e7emberinin i\u00e7erisine d\u00fc\u015ft\u00fcm \/ alevler y\u00fckseldik\u00e7e a\u015fa\u011f\u0131, a\u015fa\u011f\u0131, a\u015fa\u011f\u0131 indim \/ ve yan\u0131yor, yan\u0131yor, yan\u0131yor \/ ate\u015f \u00e7emberi, ate\u015f \u00e7emberi<\/em> (1)<\/p>\n

Ate\u015f \u00c7emberi ayn\u0131 zamanda Pasifik Okyanusu\u2019nun etraf\u0131ndaki okyanus \u00e7ukurlar\u0131 ve yanarda\u011flardan olu\u015fan alan\u0131n ad\u0131.<\/p>\n

Manidar bir zamanlama ile sevgililer g\u00fcn\u00fcnde, bu \u00e7emberin tam i\u00e7erisinde bulunan ve d\u00fcnyan\u0131n en aktif yanarda\u011flar\u0131ndan Kilauea\u2019ya ev sahipli\u011fi yapan Hawaii adalar\u0131ndan Big Island\u2019a (B\u00fcy\u00fck Ada) u\u00e7tum. \u201cOysa i\u00e7imdeki bilim a\u015fk\u0131yd\u0131\u201d diye bir c\u00fcmle kuray\u0131m; hesaplamal\u0131 biyoloji (quantitative biology) konferans\u0131nda bir konu\u015fma yapacakt\u0131m. Zaten Ate\u015f \u00c7emberi tam bir \u00e7ember de de\u011fil; 40.000 km b\u00fcy\u00fckl\u00fc\u011f\u00fcnde bir at nal\u0131. Pasifik Okyanusu\u2019nun Asya, Amerika ve Okyanusya k\u0131y\u0131lar\u0131n\u0131 kaps\u0131yor. \u00dczerindeki 452 yanarda\u011f\u0131 ile d\u00fcnyan\u0131n hem en aktif hem de en uyuyan yanarda\u011flar\u0131n\u0131n y\u00fczde 75\u2019ini bar\u0131nd\u0131r\u0131yor. D\u00fcnyadaki depremlerin y\u00fczde 90\u2019\u0131 burada ger\u00e7ekle\u015fiyor. Yanarda\u011flar\u0131n p\u00fcsk\u00fcrtt\u00fc\u011f\u00fc s\u0131cak lav kayalar\u0131ndan olu\u015fan Hawaii Tak\u0131madas\u0131 da okyanusun i\u00e7inde, Amerika K\u0131tas\u0131\u2019n\u0131n 3700 km bat\u0131s\u0131nda yer al\u0131yor. (2)<\/p>\n

\u00dczerinden 150 y\u0131l kadar ge\u00e7mi\u015f olsa bile, Hawaii\u2019nin ruhunu en iyi Mark Twain\u2019in gezi yaz\u0131lar\u0131 anlat\u0131r. \u201c\u0130lk b\u00fcy\u00fck Amerikan roman\u0131n\u0131n yazar\u0131\u201d olarak tan\u0131nan Mark Twain, 1866\u2019da adalarda 4 ay kadar dola\u015fm\u0131\u015f. Benim kald\u0131\u011f\u0131m B\u00fcy\u00fck Ada\u2019y\u0131 at \u00fczerinde haftalarca gezmi\u015f; Kilauea Yanarda\u011f\u0131\u2019n\u0131n tepesine \u00e7\u0131km\u0131\u015f, sisli bir gece kraterin k\u00f6\u015fesinde ayakta durmu\u015f ve y\u00fcz\u00fc lav \u0131\u015f\u0131\u011f\u0131nda parlarken krateri g\u00f6zlemlemi\u015f. (3) G\u00fcn\u00fcm\u00fczde ise araba ile adan\u0131n \u00f6nemli yerleri 2-3 g\u00fcnde g\u00f6r\u00fclebiliyor. Hatta yanarda\u011fa \u00e7\u0131kan d\u00fcz bir otoban da var. O sebeple Kilauea bazen \u201cd\u00fcnyan\u0131n araba ile servis yap\u0131lan tek yanarda\u011f\u0131\u201d olarak an\u0131l\u0131yor.<\/p>\n

\"\"
Ring of Fire: Ate\u015f \u00c7emberi.<\/figcaption><\/figure>\n

Kilauea 1983\u2019te tekrar lav p\u00fcsk\u00fcrtmeye ba\u015flam\u0131\u015f. Hawaii adalar\u0131 da aktif yanarda\u011flar sayesinde b\u00fcy\u00fcmeye devam ediyor. Bu aktivite bir as\u0131r daha s\u00fcrebilir, yar\u0131n da durabilir. Akan lav kayalar\u0131n\u0131 g\u00fcnd\u00fcz g\u00f6rmek zor, fakat geceleri parlak portakal rengi lav, yanarda\u011f\u0131n yama\u00e7lar\u0131n\u0131 ve \u00fczerindeki bulutlar\u0131n rengini de\u011fi\u015ftiriyor.<\/p>\n

Lavlar\u0131n i\u00e7erisindeki mineraller sayesinde Hawaii d\u00fcnyan\u0131n ba\u015fka hi\u00e7bir yerinde g\u00f6r\u00fclmeyen bitki ve hayvanlara ev sahipli\u011fi yap\u0131yor. Adan\u0131n \u00e7e\u015fitli b\u00f6lgelerinin y\u00fczeyi de lav ak\u0131\u015f\u0131na g\u00f6re de\u011fi\u015fken. Mesela lav akt\u0131ktan bir y\u0131l kadar sonra hayat tekrar ortaya \u00e7\u0131k\u0131yor; tek t\u00fck ye\u015fillikler lav kayalar\u0131n\u0131n aras\u0131ndan filizleniyor. 10 y\u0131l i\u00e7erisinde ise y\u00fczlerce canl\u0131 o b\u00f6lgeye geri geliyor. Bir as\u0131r sonras\u0131nda ise ormanlar olu\u015fuyor.<\/p>\n

\u00c7ok yak\u0131nda: Benekli z\u00fcrafa? <\/strong><\/p>\n

Kat\u0131ld\u0131\u011f\u0131m konferans Hawaii \u00dcniversitesi\u2019nin katk\u0131lar\u0131yla d\u00fczenlenmi\u015f. Ama\u00e7 d\u00fcnyan\u0131n her yerinden biliminsanlar\u0131n\u0131 Hawaii ile bulu\u015fturmak.<\/p>\n

Konferans\u0131n g\u00f6rsel olarak en heyecan verici konu\u015fmas\u0131n\u0131, Japonya\u2019n\u0131n Osaka \u00dcniversitesi\u2019nden Shigeru Kondo, bal\u0131k derisindeki desen olu\u015fumu \u00fczerine yapt\u0131.<\/p>\n

Kondo\u2019nun \u00e7al\u0131\u015fmas\u0131n\u0131n temelleri b\u00fcy\u00fck matematik\u00e7i Alan Turing\u2019in ya\u015fam\u0131n\u0131n son g\u00fcnlerinde biyoloji ve kimya \u00fczerine yay\u0131mlad\u0131\u011f\u0131 tek makalesine dayan\u0131yor. Turing\u2019e g\u00f6re belli tip kimyasal reaksiyonlar do\u011fada g\u00f6r\u00fclen pek \u00e7ok deseni (paterni) a\u00e7\u0131klayabilmeliydi (\u00e7izgili, benekli, leopar desenleri mesela). Turing\u2019in 1952\u2019de yay\u0131mlanan ve \u201c\u015eekil geli\u015fimine yol a\u00e7an biyolojik i\u015flemlerin kimyasal temeli\u201d (The Chemical Basis of Morphogenesis) diye \u00e7evirebilece\u011fimiz makalesi, tamamen teori a\u011f\u0131rl\u0131kl\u0131yd\u0131; deneysel olarak kan\u0131tlanmam\u0131\u015ft\u0131. Turing\u2019in vefat\u0131ndan sonraki y\u0131llarda, bu teorik \u00e7al\u0131\u015fmas\u0131n\u0131n pek \u00e7ok biyolojik ve kimyasal olay\u0131 a\u00e7\u0131klad\u0131\u011f\u0131 ortaya \u00e7\u0131kmaya ba\u015flad\u0131. \u0130lk olarak yemek tak\u0131mlar\u0131ndaki kimyasallarda, sonra da hayvanlar\u0131n parmak izlerinde Turing desenleri bulundu. Kimileri Turing paternlerinin ekosistemlere ve hatta galaksilere uzat\u0131labilece\u011fini iddia etti.<\/p>\n

Kondo ve \u00e7al\u0131\u015fma arkada\u015flar\u0131 ise zebrabal\u0131\u011f\u0131n\u0131n (zebrafish) \u00fczerindeki zebra desenli \u00e7izgilerin Turing modeline uydu\u011funu ke\u015ffetmi\u015f. Bu desenler, yavru zebrabal\u0131\u011f\u0131n\u0131n derisinde birka\u00e7 noktada ortaya \u00e7\u0131k\u0131yor ve yeti\u015fkin bal\u0131klarda kar\u0131\u015f\u0131k motiflere d\u00f6n\u00fc\u015f\u00fcyor. 2008\u2019de lazerle yavru zebrabal\u0131\u011f\u0131 derisinde yara izleri a\u00e7m\u0131\u015flar ve sonra bu desenlerin nas\u0131l geli\u015fti\u011fini izlemi\u015fler. Desenler t\u00fcm\u00fcyle Turing\u2019in denklemlerine dayal\u0131 bilgisayar sim\u00fclasyonlar\u0131n\u0131n tahminlerine uygun \u015fekilde geli\u015fmi\u015f.<\/p>\n

Turing desen olu\u015fumu i\u00e7in gerekli ko\u015fullar ise, deri \u00fczerinde b\u00f6lgesel pozitif geri bilgi ak\u0131\u015f\u0131 (feedback) ve uzun mesafeli negatif geri bilgi ak\u0131\u015f\u0131. Bu mekanizmada rol alan genleri de belirleyen Kondo ve grubu, art\u0131k genleri manip\u00fcle edip istedikleri t\u00fcr deseni bal\u0131k derisinde yaratabiliyor. Hatta do\u011fada bulunan \u00e7o\u011fu hayvandaki pigment desenlerini cx418 isimli bir geni de\u011fi\u015ftirerek elde edebileceklerini iddia ediyorlar. E\u011fer kaynak bulabilirse Kondo, Afrika\u2019da z\u00fcrafalar\u0131n paternlerini de\u011fi\u015ftiren deneyler yapmak istiyor! Konu\u015fmas\u0131n\u0131n sonunda ise ba\u015far\u0131lar\u0131n\u0131 ara\u015ft\u0131rma gurubunun yaratt\u0131\u011f\u0131 b\u00fcy\u00fck benekli bal\u0131k foto\u011fraf\u0131yla kan\u0131tl\u0131yor.<\/p>\n

\u0130ki yanl\u0131\u015f\u0131n bir do\u011fruya g\u00f6t\u00fcrmesi: T\u00fcm\u00f6rde ya\u015fayan bakteriler<\/strong><\/p>\n

\u00c7ok enteresan di\u011fer bir konu\u015fma ise kanser te\u015fhis ve tedavisinde bakteri kullanmay\u0131 ama\u00e7layan post-doktora ara\u015ft\u0131rmac\u0131s\u0131 Tal Danino taraf\u0131ndan sunuldu.<\/p>\n

Dr. Danino Massachusetts Teknoloji Enstit\u00fcs\u00fc\u2019nde Sangeeta Bhatia ile beraber yapt\u0131\u011f\u0131 \u00e7al\u0131\u015fmada, bakterileri v\u00fccut i\u00e7erisinde \u00f6zel ila\u00e7 ta\u015f\u0131ma kuryesi olarak programlamay\u0131 ama\u00e7l\u0131yor. Bu ama\u00e7la bakterinin DNA dizilimini de\u011fi\u015ftirerek genleriyle oynuyorlar.<\/p>\n

Mesela bakteriler t\u00fcm\u00f6r ortam\u0131nda b\u00fcy\u00fcyebiliyor. Asl\u0131nda bu tamamen rastlant\u0131 eseri ke\u015ffedilmi\u015f: Boynunda t\u00fcm\u00f6r bulunan bir kad\u0131n hastaya yanl\u0131\u015fl\u0131kla ayn\u0131 yatakta kalan bir \u00f6nceki hastan\u0131n bakterileri bula\u015f\u0131yor. T\u00fcm\u00f6r\u00fcn i\u00e7erisine giren bakteri t\u00fcm\u00f6r\u00fcn b\u00fcy\u00fcmesini durduruyor. 1868\u2019de ise Alman doktorlar Busch ve Fehleisen bilerek bir kanser hastas\u0131na bir deri iltihab\u0131 hastal\u0131\u011f\u0131 olan y\u0131lanc\u0131k (erysipelas) bula\u015ft\u0131r\u0131yor ve t\u00fcm\u00f6r\u00fcn k\u00fc\u00e7\u00fcld\u00fc\u011f\u00fcn\u00fc g\u00f6zlemliyorlar. Fehleisen daha sonra, 1882\u2019de bu tedaviyi tekrar uyguluyor ve sonras\u0131na Streptococcus pyogenes<\/em> bakterisinin y\u0131lanc\u0131k hastal\u0131\u011f\u0131n\u0131n sebebi oldu\u011funu ke\u015ffediyor. ABD\u2019li cerrah W. B. Coley ise bu tedaviyi sistematik olarak kemik kanseri hastalar\u0131nda uyguluyor.<\/p>\n

Fehleisen\u2019in deneylerinden beri, bakterinin t\u00fcm\u00f6re giri\u015finin molek\u00fcler mekanizmalar\u0131n\u0131 anlamaya ba\u015flad\u0131k. Bakteri t\u00fcm\u00f6re girdi\u011fi zaman sadece t\u00fcm\u00f6rde b\u00fcy\u00fcyor; v\u00fccudun ba\u015fka b\u00f6lgesinde b\u00fcy\u00fcm\u00fcyor. Bhatia grubunun amac\u0131 ise t\u00fcm\u00f6r\u00fcn i\u00e7ine ila\u00e7 ta\u015f\u0131yabilen bakteri \u00fcretmek. Bu sayede ila\u00e7 t\u00fcm\u00f6r h\u00fccrelerini \u00f6ld\u00fcr\u00fcp sa\u011fl\u0131kl\u0131 h\u00fccrelere en az zarar\u0131 verecek. Bakteri t\u00fcm\u00f6re damardan giriyor ve t\u00fcm\u00f6r ortam\u0131nda b\u00fcy\u00fcmeyi sa\u011fl\u0131kl\u0131 ortamda b\u00fcy\u00fcmeye tercih ediyor. \u0130lac\u0131 bakteri ile t\u00fcm\u00f6re ta\u015f\u0131mak nanopar\u00e7ac\u0131klar ile t\u00fcm\u00f6re ta\u015f\u0131maktan daha avantajl\u0131, \u00e7\u00fcnk\u00fc bakterinin say\u0131s\u0131 bir g\u00fcnde do\u011fal \u00e7o\u011falmayla bir milyondan bir milyara \u00e7\u0131kabiliyor.<\/p>\n

Bhatia grubu \u00f6zellikle karaci\u011fer metastaz\u0131nda b\u00fcy\u00fcyen t\u00fcm\u00f6rlerin te\u015fhis ve tedavisi ama\u00e7l\u0131 deneylere odaklanm\u0131\u015f. Kolon kanseri h\u00fccrelerini farelere a\u015f\u0131lad\u0131klar\u0131nda karaci\u011ferde metastaz oluyor. Bu metastazl\u0131 farelere E. coli Nissle<\/em> probioti\u011fi hap\u0131 vermi\u015fler. E. coli Nissle<\/em> nedir derseniz, 1. D\u00fcnya Sava\u015f\u0131 s\u0131ras\u0131nda hi\u00e7bir mide ya da ba\u011f\u0131rsak hastal\u0131\u011f\u0131na yakalanmam\u0131\u015f olan bir askerden al\u0131nm\u0131\u015f bir bakteri. Genellikle mide ve ba\u011f\u0131rsak rahats\u0131zl\u0131klar\u0131nda tedavi ama\u00e7l\u0131 kullan\u0131lan bu bakteri de farelerin sa\u011fl\u0131kl\u0131 b\u00f6lgeleri yerine karaci\u011fer metastaz b\u00f6lgesine yerle\u015fip \u00e7o\u011falmay\u0131 tercih ediyor. \u00c7o\u011falan bakterilerin \u00e7ok say\u0131da \u00fcretti\u011fi bir enzim idrarda belli bir molek\u00fcl\u00fcn miktar\u0131n\u0131 artt\u0131r\u0131yor. Bu art\u0131\u015f da idrarda metastaz sinyali olarak kullan\u0131labiliyor. Yani bu sayede kolon kanserinin metastaza yol a\u00e7\u0131p a\u00e7mad\u0131\u011f\u0131, v\u00fccuda zarar vermeden sadece idrar tahliliyle bulunabilecek.<\/p>\n

Hawaii\u2019de T\u00fcrk doktora \u00f6\u011frencileri<\/strong><\/p>\n

Konferansta iki T\u00fcrk doktora \u00f6\u011frencisine rastlad\u0131m: O\u011fuzhan Atay<\/strong>, Samsun Bafra\u2019daki ailesinden k\u00fc\u00e7\u00fck ya\u015fta e\u011fitim a\u015fk\u0131 ile ayr\u0131l\u0131p hem Ko\u00e7 Lisesi\u2019nde yat\u0131l\u0131 burslu, hem de Princeton \u00dcniversitesi\u2019nde burslu lisans e\u011fitimi alm\u0131\u015f. \u015eu anda Stanford \u00dcniversitesi\u2019nde lisans\u00fcst\u00fc e\u011fitimine devam ediyor. H\u00fcseyin Ta\u015f<\/strong> ise Bursa Fen Lisesi ve Sabanc\u0131 \u00dcniversiteleri\u2019nin ikisini de burslu okuduktan sonra \u0130llinois \u00dcniversitesi\u2019nin Urbana Champaign kamp\u00fcs\u00fcnde doktoras\u0131na devam ediyor. \u0130kisi de konferans\u0131 \u00f6n s\u0131ralardan ilgiyle takip etti. Onlar ara\u015ft\u0131rmalar\u0131n\u0131 sunarlarken do\u011frusu gurur duydum.<\/p>\n

Dipnotlar<\/strong><\/p>\n

1) \u0130ngilizce orijinali: I fell into a burning ring of fire \/ I went down, down, down, as the flames went higher \/ And it burns, burns, burns, The ring of fire, the ring of fire.<\/em><\/p>\n

2) \u0130statistiksel co\u011frafi bilgileri, wikipedia websitesinden ald\u0131m.<\/p>\n

3) Grove, D. A. (edit\u00f6r); Mark Twain\u2019s Letters from Hawaii<\/em>, Hawaii \u00dcnv. Yay\u0131nlar\u0131, 1989 (Mark Twain\u2019in Sacramento Union<\/em> gazetesinde yay\u0131mlanan 25 mektubunu i\u00e7eriyor).<\/p>\n

4) Grove, D. A. (edit\u00f6r); Mark Twain in Hawaii: Roughing it out in the Sandwich Islands: Hawaii in the 1860s<\/em>, Mutual Yay., 1990.<\/p>\n

5) Kondo S., Miura T. (2010); \u201cReaction-diffusion model as a framework for understanding biological pattern formation\u201d, <\/em>Sep 2 24; 329 (5999): 1616-20.<\/p>\n

6) Turing, A. M. (1952), \u201cThe chemical basis of morphogenesis\u201d, Philosophical Transactions of the Royal Society of London<\/em>, 237 (641): 37-72.<\/p>\n

7) Danino T., Li J., Prindle A., Hasty J., Bhatia S.N. (2012); \u201cIn vivo gene expression dynamics of tumor-targeted bacteria\u201d, ACS Synthetic Biology<\/em>. Oct 19; 1(10): 465-470.<\/p>\n","protected":false},"excerpt":{"rendered":"

Efsanevi Amerikan country m\u00fczisyeni Johnny Cash, hit \u015fark\u0131s\u0131 Ring of Fire\u2019da a\u015fk\u0131 bir ate\u015f \u00e7emberinin i\u00e7inde olmaya benzetir: Yanan bir ate\u015f \u00e7emberinin i\u00e7erisine d\u00fc\u015ft\u00fcm \/ alevler y\u00fckseldik\u00e7e a\u015fa\u011f\u0131, a\u015fa\u011f\u0131, a\u015fa\u011f\u0131 indim \/ ve yan\u0131yor, yan\u0131yor, yan\u0131yor \/ ate\u015f \u00e7emberi, ate\u015f \u00e7emberi (1) Ate\u015f \u00c7emberi ayn\u0131 zamanda Pasifik Okyanusu\u2019nun etraf\u0131ndaki okyanus \u00e7ukurlar\u0131 ve yanarda\u011flardan olu\u015fan alan\u0131n […]<\/p>\n","protected":false},"author":555,"featured_media":26900,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[158,744],"tags":[3495,3496],"class_list":["post-26898","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-121-sayi","category-bilumum-bilim","tag-ates-cemberi","tag-hawaii"],"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