Visualization of R-bands in human metaphase chromosomes by the restriction endonuclease MseI.
Human metaphase chromosomes were treated with the restriction endonuclease MseI, which cuts DNA at TTAA sequences. This enzyme preferentially cuts and extracts DNA from G-bands and thus is the first restriction endonuclease allowing direct R-band visualization. Specific patterns ranging from R+C-like to C-like banding can be induced, depending on the concentration of the enzyme. At intermediate concentrations, only a subset of R-bands are produced, corresponding to GC-rich bands that are especially resistant to heat denaturation (so-called T-bands). These results suggest that compositional differences between chromosomal regions determine the different rates of cleavage by MseI, not only between R- and G-bands but also among different R-bands.
Departamento de Biología, Facultad de Ciencias, Módulo C-XV, Universidad Autónoma de Madrid, Spain.
P
P
Ludeña
C
C
Sentís
S F
SF
De Cabo
M
M
Velázquez
J
J
Fernández-Piqueras
D001483:Base Sequence; D002478:Cells, Cultured; D002871:Chromosome Banding; D015252:Deoxyribonucleases, Type II Site-Specific / Q000378:metabolism; D005260:Female; D006801:Humans; D007621:Karyotyping; D008214:Lymphocytes / Q000166:cytology; D008297:Male; D008677:Metaphase; D008969:Molecular Sequence Data; D013379:Substrate Specificity
C055927:endodeoxyribonuclease MseI; D015252:Deoxyribonucleases, Type II Site-Specific