Analysis of NORs and NOR-associated heterochromatin in the mussel Mytilus galloprovincialis Lmk.
The chromosomes of the mussel Mytilus galloprovincialis were analysed by means of chromomycin A3 (CMA), distamycin A/DAPI (DA/DAPI), DAPI/actinomycin D (DAPI/AMD) and chromomycin A3/distamycin A/DAPI (CDD) fluorescence banding techniques, C-banding, silver staining, N-banding and in situ hybridization with 18S+28S rDNA and telomere probes. 18S+28S rDNA clusters were located on the telomeres of two pairs of submeta/subtelocentric chromosomes. The nucleolar organizing regions (NORs) were associated with bright CMA fluorescence, dull DAPI fluorescence and C- and N-positive bands, but not all four NOR-associated heterochromatin bands showed bright CMA fluorescence in a given cell; intra- and interindividual variability was found in this character. Additional non-ribosomal C-bands did not show any differential fluorescent behaviour.
Martínez-Expósito
M J
MJ
Dpto. Bioloxía Fundamental, Xenética, Universidade de Vigo, Spain.
Méndez
J
J
Pasantes
J J
JJ
D000818:Animals; D049872:Bivalvia / Q000235:genetics*; D002466:Cell Nucleolus / Q000235:genetics*; D005880:Gills / Q000648:ultrastructure; D006570:Heterochromatin / Q000235:genetics*; D017403:In Situ Hybridization; D009697:Nucleolus Organizer Region / Q000235:genetics*; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D012339:RNA, Ribosomal, 28S / Q000235:genetics; D013194:Staining and Labeling / Q000379:methods; D016615:Telomere / Q000235:genetics; D014982:Xenopus laevis / Q000235:genetics
D006570:Heterochromatin; D012337:RNA, Ribosomal, 18S; D012339:RNA, Ribosomal, 28S