Naslov
Structure and organisation of rDNA chromatin in the nucleus and nucleolus of Quercus species related to rRNA gene expression.

Autori
Zoldoš Pećnik, V., Maglica, Ž., Papeš, D., Ljubešić, N., Šiljak-Yakovlev, S.

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, ostalo

Izvornik
Conference Proceedings / - Zagreb, 2006

Skup
EMBO/HHMI Central European Scientists Meeting

Mjesto i datum
Dubrovnik, Hrvatska, 15.06.2006. - 17.06.2006

Vrsta sudjelovanja
Poster

Vrsta recenzije
Nije recenziran

Ključne riječi
ekspresija gena; 18S-5.8S-26S rRNA geni; jezgrica; Quercus
(gene expression; 18S-5.8S-26S rRNA genes; nucleolus; Quercus)

Sažetak
RRNA genes comes in eukaryotic genomes in redundant number and only subset of the genes are transcriptionally active. Little is know about the mechanisms regulating their activity. rDNA chromatin exists in two different structures, an “ open” or decondensed one and a “ closed” or condensed one, that can modulate gene expression. Enhancer-imbalance mechanism assumes difference in length of non-transcribed spacer region to be related to transcriptional activity of certain genes in the cluster. The aim of the present study was to reveal: a) location of rDNA loci within the nucleus and nucleolus and the patterns of gene expression related to rDNA chromatin structure, b) number of different spacer length variants (slvs) in rDNA system of several Quercus species. Quercus species have two rDNA loci, a major and minor one, positioned on different chromosomes. Previous studies have indicated that only the major rDNA locus is active. In this study we showed that this locus consists of both condensed and decondensed chromatin that can be identified cytogenetically as different types of hybridisation signal when rRNA genes were used as probe for in situ hybridisation. Structural pattern of rDNA chromatin stayed constant during the cell cycle, however it varied in population of the same and different Quercus species. Distribution of the two rDNA chromatin structures in metaphases/interphases was directly related with the location and organization of the rDNA chromatin in the nucleolus at electron microscopic level. Both types of rDNA chromatin were found inside the nucleolus indicating that not only active genes were involved in nucleolar formation. In Quercus, activity probably occurred at genes interspersed along each site of the major rDNA locus, with the expressed rDNA sites separated with condensed unexpressed sites. PCR amplification of spacer region revealed 1 to 9 slvs in nine individuals of Q. petraea, and the results were discussed in respect to expression patterns.

Izvorni jezik
Engleski

Znanstvena područja
Biologija

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