Abstract
Down sendromu (DS) ya da Trizomi 21 en genel ve en iyi bilinen kromozom anomalilerinden biridir. Bu anomalinin genel sebeplerinden birtanesi, mayozda homolog kromozomların ayrılmasında meydana gelen aksaklıklardır
(nondisjunction). Bu olay büyük çoğunlukla oogenezis sırasında oluşur ve bu nedenle DS’deki anormal gametlerin
kaynağı genellikle yumurta hücresidir. Hücrenin çekirdeği içerisinde oluşan NORs (Nucleolar Organiser Regions)’lar tandem şeklinde tekrarlanan, ribozomal DNA ilmekleridir. İnsan genomunda NOR’lar 5 çift akrosentrik kromozomun (13, 14, 15, 21, 22) ikincil boğumlarında yerleşirler. İnterfazda transkripsiyonel olarak aktif olan NOR’lar, uygun şartlar altında gümüş nitrat ile seçici olarak boyanabilirler.
AgNOR proteini sentezinin çocuk’lardaki gelişimi etkileyip etkilemediğini tespit etmek amacıyla, yaşları 5,5 ay ile 64 ay arasında değişen 20 DS’lu çocuk çalışmaya dahil edilmiştir. İlk olarak psikolog tarafından bireylere Ankara
Gelişim Tarama Envanteri (AGTE) testi uygulanarak gelişim düzeyleri dil-bilişsel, ince motor, kaba motor, sosyal beceri-öz bakım ve genel gelişim olarak belirlenmiştir. Daha sonra bu çocukların herbirisinden steril bir kürdan yardımıyla
ağız epiteli alınarak bir lam üzerine yayma yapılmıştır. Daha sonra herbir preperata AgNOR boyama işlemi uygulanıp,
her bir çekirdek için AgNOR sayısı özel bir bilgisayar proğramı kullanılarak tespit edilmiştir. Her bir bireyden 100
çekirdek değerlendirilmiş ve her biri için ortalama NOR sayısı değerleri hesaplanmıştır. Bulgulara göre ortalama NOR sayısı/çekirdek oranı 4.53±0.82 bulunmuştur. Veriler, Spearmen korelasyon testi uygulanarak her bir gelişim düzeyi için istatistiksel olarak analiz edilmiştir. Bu bulgulara göre, sırasıyla dil-bilişsel, ince motor, kaba motor, sosyal beceri-öz bakım ve genel gelişim ile NOR sayısı arasında anlamlı bir ilişki bulunamamıştır (p>0.05). Sonuç olarak NOR sayısında meydana gelen artma ve azalmaların AGTE testine göre DS’ların gelişim düzeylerine bir etkisi yoktur.
Keywords
References
- Greber-Platzer S, Schatzmann-Turhani D, Wollenek G, Lubec G: Evidence against the current hypothesis of gene dosage effects of Trisomy 21: ets-2, encoded on chromosome 21 is not overexpressed in hearts of patients with Down syndrome. Biochem. Biophys. Res. Commun 254, 395–399, 1999.
- Antonarakis SE, Lyle R, Chrast R, Scott HS: Differential gene expression studies to explore the molecular pathophysiology of Down syndrome. Brain Res. Rev. 36, 265–274, 2001.
- Demirtas H, Imamoglu N, Cucer N, Donmez H, Yilmaz A, Candemir Z, Bokesoy I. NOR (rDNA) expression enhancement in phytohemagglutinin- stimulated lymphocytes of Down syndrome patients. Erciyes University J. Health Sci. 8, 24–27, 1999.
- Demirtas H, Imamoglu N, Donmez H, Cucer N, Yilmaz A, Candemir Z: Condensed chromatin surface and NOR surface enhancement in mitogen-stimulated lymphocytes of Down syndrome patients. Ann. Ge´ne´t- Paris 44, 77–82, 2001.
- Imamoglu N, Demirtas H, Donmez-Altuntas H, Hamurcu Z, Ilten A: NORs Expression increases on metaphase chromosomes of Down syndrome lymphocytes, in concordance with the mitogen concentration in the culture medium. Cytometry Part B-Clin Cytom. 66B, 36–39, 2005a.
- Imamoglu N, Demirtas H, Donmez-Altuntas H, Ilten A: Higher NORs expression in lymphocyte of trisomy 21 babies/children: in vivo evaluation. Micron 36, 503–507, 2005b.
- Savaşır I, Sezgin N, Erol N: Ankara Gelişim Tarama Envanteri (2. basım) Türk Psikologlar Derneği: Ankara, 1993.
- Hernandez-Verdun D: The nucleolus: a model for the organization of nuclear functions Histochem Cell Biol 126:135–148, 2006.
- Manu SCV, Rajaram BT, Rai LR: Value of Silver Binding Nucleolar Organiser Regions (AgNOR) in Squamous Cell Carcinomas of Upper Aero-digestive Tract. MJAFI ; 62 : 123- 128, 2006.
- Lindner LE: Improvements in the Silver-staining technique for nucleolar organizer regions (AgNOR). J Histochem Cytochem 41(3): 439-445, 1993.
- Gardiner K, Slavov D, Bechtel L, Davisson M: Annotation of human chromosome 21 for relevance to Down syndrome: gene structure and expression analysis. Genomics 79(6):833-843, 2002.
- Gardiner K, Fortna A, Bechtel L, Davisson MT: Mouse models of Down syndrome: how useful can they be? Comparison of the gene content of human chromosome 21 with orthologous mouse genomic regions. Gene 318:137-147, 2003.
- McQuillan CI, Choo KH : Comparison of total cellular DNA, mRNA, and rRNA levels between normals and Down syndrome patients. J Inher Metab Dis 15:112-120, 1992.
- Kadota M, Nishigaki R, Wang CC, Toda T, Shirayoshi Y, et al. Proteomic signatures and aberrations of mouse embryonic stem cells containing a single human chromosome 21 in neuronal differentiation: an in vitro model of Down syndrome. Neuroscience 129:325-335, 2004.
- Imamoglu N, Demirtas H, Ilten A: NOR Expression increases in interphase lymphocytes of Down syndrome babies/children as AgNORs surface, according to the mitogen concentration in the culture medium. Micron 37:129–133, 2006.
Abstract
References
- Greber-Platzer S, Schatzmann-Turhani D, Wollenek G, Lubec G: Evidence against the current hypothesis of gene dosage effects of Trisomy 21: ets-2, encoded on chromosome 21 is not overexpressed in hearts of patients with Down syndrome. Biochem. Biophys. Res. Commun 254, 395–399, 1999.
- Antonarakis SE, Lyle R, Chrast R, Scott HS: Differential gene expression studies to explore the molecular pathophysiology of Down syndrome. Brain Res. Rev. 36, 265–274, 2001.
- Demirtas H, Imamoglu N, Cucer N, Donmez H, Yilmaz A, Candemir Z, Bokesoy I. NOR (rDNA) expression enhancement in phytohemagglutinin- stimulated lymphocytes of Down syndrome patients. Erciyes University J. Health Sci. 8, 24–27, 1999.
- Demirtas H, Imamoglu N, Donmez H, Cucer N, Yilmaz A, Candemir Z: Condensed chromatin surface and NOR surface enhancement in mitogen-stimulated lymphocytes of Down syndrome patients. Ann. Ge´ne´t- Paris 44, 77–82, 2001.
- Imamoglu N, Demirtas H, Donmez-Altuntas H, Hamurcu Z, Ilten A: NORs Expression increases on metaphase chromosomes of Down syndrome lymphocytes, in concordance with the mitogen concentration in the culture medium. Cytometry Part B-Clin Cytom. 66B, 36–39, 2005a.
- Imamoglu N, Demirtas H, Donmez-Altuntas H, Ilten A: Higher NORs expression in lymphocyte of trisomy 21 babies/children: in vivo evaluation. Micron 36, 503–507, 2005b.
- Savaşır I, Sezgin N, Erol N: Ankara Gelişim Tarama Envanteri (2. basım) Türk Psikologlar Derneği: Ankara, 1993.
- Hernandez-Verdun D: The nucleolus: a model for the organization of nuclear functions Histochem Cell Biol 126:135–148, 2006.
- Manu SCV, Rajaram BT, Rai LR: Value of Silver Binding Nucleolar Organiser Regions (AgNOR) in Squamous Cell Carcinomas of Upper Aero-digestive Tract. MJAFI ; 62 : 123- 128, 2006.
- Lindner LE: Improvements in the Silver-staining technique for nucleolar organizer regions (AgNOR). J Histochem Cytochem 41(3): 439-445, 1993.
- Gardiner K, Slavov D, Bechtel L, Davisson M: Annotation of human chromosome 21 for relevance to Down syndrome: gene structure and expression analysis. Genomics 79(6):833-843, 2002.
- Gardiner K, Fortna A, Bechtel L, Davisson MT: Mouse models of Down syndrome: how useful can they be? Comparison of the gene content of human chromosome 21 with orthologous mouse genomic regions. Gene 318:137-147, 2003.
- McQuillan CI, Choo KH : Comparison of total cellular DNA, mRNA, and rRNA levels between normals and Down syndrome patients. J Inher Metab Dis 15:112-120, 1992.
- Kadota M, Nishigaki R, Wang CC, Toda T, Shirayoshi Y, et al. Proteomic signatures and aberrations of mouse embryonic stem cells containing a single human chromosome 21 in neuronal differentiation: an in vitro model of Down syndrome. Neuroscience 129:325-335, 2004.
- Imamoglu N, Demirtas H, Ilten A: NOR Expression increases in interphase lymphocytes of Down syndrome babies/children as AgNORs surface, according to the mitogen concentration in the culture medium. Micron 37:129–133, 2006.
Details
| Primary Language | Turkish |
|---|---|
| Journal Section | Research Articles |
| Authors | |
| Publication Date | March 14, 2011 |
| Submission Date | March 14, 2011 |
| Published in Issue | Year 2011 Volume: 1 Issue: 1 |
