Author(s): Tomás, Diana Raquel dos Santos
Date: 2010
Persistent ID: http://hdl.handle.net/10400.5/2974
Origin: Repositório da UTL
Subject(s): secale cereale; high temperature stress; ribossomal DNA; subtelomeric pSc200; nucleolus; stress de alta temperatura; DNA ribossomal; subtelomerica pSc200
Mestrado em Biologia Funcional - Instituto Superior de Agronomia
The aim of this work was to evaluate the influence of high temperature stress (HTS) in the chromatin organization of two repetitive sequences – 45S ribossomal DNA and subtelomeric pSc200 – and of nucleoli in interphase root tips and coleoptiles nuclei from Secale cereale seedlings using fluorescent in situ hybridization and imunocitochemestry, respectively. Furthermore we analyzed the influence of high temperature stress in the transcription patterns of the same sequences through quantitative real-time PCR. Nuclei from both organs show different conformation patters. Root tips nuclei have bigger dimensions, more disperse subtelomeric FISH signals and more compact ribossomal probe. We observe that high temperature stress causes chromatin decondensation in both sequences in root tips nuclei, while in coleoptile nuclei, beside the rDNA decondensation, we observe an increase in the nuclear area suggesting a global nuclear decompactation. The nucleolar area is also higher in both types of nuclei of stressed seedlings. This increase could be correlated with the increase in the ribossomal genes expression level induced by temperature stress, demonstrated through real-time PCR. The present work describes for the first time that the subtelomeric sequence pSc200 is transcribed, although its levels are not significantly altered with high temperature stress.
