Tez özetleri Astronomi ve Uzay Bilimleri Anabilim Dalı

Investigation of Nitric Oxide Dependent Changes in Gene Expression in Schizosaccharomyces Pombe

Nitric oxide (NO) which is known to play important regulatory roles in various physiological processes in mammals is also shown to have some phsysiological functions in broad range of species other than the mammals, and nitric oxide synthase (NOS) like enzymes catalyzing NO production were found in these organisms. Presence of NOS activity has not been reported to date in Schizosaccharomyces pombe which is believed to be a convenient model organism since it shares a number of characteristic similarities with the mammalian cells at the molecular level, and very little is known about the phsysiological roles of NO in this yeast species.

In this study, we firstly aimed to find out whether S. pombe cell extracts had NOS activity, then in order to detect the genes which are sensitive to both decreased and elevated intracellular NO levels. We also aimed to investigate if NO could function in regulation of some phsyiological processes as a signaling molecule in relation with the cellular functions of NO sensitive genes to be detected in S. pombe cells.

NOS like activity was detected in the S. pombe crude cell extracts for the first time using a spectrofluorometric NOS assay. In order to detect the NO responsive genes, the cDNAs whose expression ratios decreased or repressed upon exposure to a NOS inhibitor NG-nitro-L-arginine methyl ester (L-NAME), and elevated in response to a NO donor sodium nitroprusside (SNP) treatment were determined by employing differential display technique. BLAST analysis of the differentially expressed cDNAs sequences, performed in S. pombe genome database, produced significant similarities to PBC17A3.09c, SPCC553.12c, byr1, pek1, sid1, wis1, ppk14 and ubp12 genes of S. pombe. pek1, sid1 and ubp12 genes were quantitatively confirmed to be sensitive to the changes in the intracellular NO levels by employing real time polymerase chain reaction.

The data obtained from the experiments regarding the functions of pek1, sid1 and ubp12 genes addressed to the possibility that NO could have some regulatory roles in mitosis, meiosis, sporulation and apoptosis in S. pombe. Moreover, it may also be possible to suggest that the effects of NO on cell divisions and stress response pathways in this yeast are exerted through activation of some MAPK signaling pathway components. In addition, these findings may also imply that S. pombe can be used as a convenient model system for investigating the cellular effects of NO at the molecular level, as the NO responsive genes detected in S. pombe share similar functions with those of the mammalian homologs.

DEMİRGAN Recep

Danışman : Yard.Doç.Dr. Ali KARAGÖZ

Anabilim Dalı : Moleküler Biyoloji ve Genetik

Mezuniyet Yılı : 2009

Tez Savunma Jürisi : Prof.Dr. Güler TEMİZKAN

Prof.Dr. Avni KURU

Prof.Dr. Nermin GÖZÜKIRMIZI

Prof.Dr. Nezhun GÖREN

Yard.Doç.Dr. Ali KARAGÖZ