Molecular and cytogenetic characterization of an AT-rich satellite DNA family in Urvillea chacoensis Hunz. (Paullinieae, Sapindaceae).
Urvillea chacoensis is a climber with 2n = 22 and some terminal AT-rich heterochromatin blocks that differentiate it from other species of the genus. The AT-rich highly repeated satellite DNA was isolated from U. chacoensis by the digestion of total nuclear DNA with HindIII and XbaI and cloned in Escherichia coli. Satellite DNA structure and chromosomal distribution were investigated. DNA sequencing revealed that the repeat length of satDNA ranges between 721 and 728 bp, the percentage of AT-base pairs was about 72-73% and the studied clones showed an identity of 92.5-95.9%. Although this monomer has a tetranucleosomal size, direct imperfect repetitions of ~180 bp subdividing it in four nucleosomal subregions were observed. The results obtained with FISH indicate that this monomer usually appears distributed in the terminal regions of most chromosomes and is associated to heterochromatin blocks observed after DAPI staining. These observations are discussed in relation to the satellite DNA evolution and compared with other features observed in several plant groups.
Urdampilleta
Juan D
JD
Laboratório de Biossistematica, Departamento de Botânica, Instituto de Biologia, Universidade Estadual de Campinas, Caixa Postal: 6109, Campinas, SP CEP 13083-970, Brazil. juanurdampilleta@hotmail.com
de Souza
Anete Pereira
AP
Schneider
Dilaine R S
DR
Vanzela
André L L
AL
Ferrucci
María S
MS
Martins
Eliana R F
ER
D020856:AT Rich Sequence; D001483:Base Sequence; D003582:Cytogenetics; D018744:DNA, Plant / Q000737:chemistry*; D004275:DNA, Ribosomal / Q000737:chemistry; D004276:DNA, Satellite / Q000737:chemistry*; D018745:Genome, Plant; D006570:Heterochromatin; D017404:In Situ Hybridization, Fluorescence; D008969:Molecular Sequence Data; D029631:Sapindaceae / Q000235:genetics*
D018744:DNA, Plant; D004275:DNA, Ribosomal; D004276:DNA, Satellite; D006570:Heterochromatin