title: Holocentric chromosomes of psocids (Insecta, Psocoptera) analysed by C-banding, silver impregnation and sequence specific fluorochromes CMA3 and DAPI.
abstract: The pattern of nucleolus attachment and C-heterochromatin distribution and molecular composition in the karyotypes of psocid species Psococerastis gibbosa (2n = 16+X), Blaste conspurcata (2n = 16+X) and Amphipsocus japonicus (2n = 14+neo-XY) were studied by C-banding, silver impregnation and sequence specific fluorochromes CMA3 and DAPI. Every species was found to have a single nucleolus in male meiosis. In P. gibbosa the nucleolus is attached to an autosomal bivalent; in B. conspurcata to the X-chromosome; in A. japonicus to the neo-XY bivalent. The species show a rather small amount of constitutive heterochromatin, C-blocks demonstrating telomeric localization with rare exceptions. P. gibbosa is characterized by a polymorphism for C-blocks occurrence and distribution. In the autosomes of this species, C-heterochromatin consists of AT-rich DNA except for the nucleolus organizing region, which is also GC-rich; the X-chromosome shows both AT- and GC-rich clusters. In A. japonicus and B. conspurcata, C-heterochromatin of the autosomes and sex chromosomes consists of both GC-rich and AT-rich DNA clusters, which are largely co-localized.
authors.affiliation: Department of Karyosystematics, Zoological Institute Russian Academy of Sciences, 199034 St. Petersburg, Russia. psocid@zin.ru
authors.forename: Natalia V
authors.initials: NV
authors.lastname: Golub
authors.forename: Seppo
authors.initials: S
authors.lastname: Nokkala
authors.forename: Valentina G
authors.initials: VG
authors.lastname: Kuznetsova
mesh_terms: D000818:Animals; D014128:Chromomycin A3 / Q000737:chemistry*; D002871:Chromosome Banding / Q000379:methods; D002875:Chromosomes / Q000737:chemistry / Q000648:ultrastructure*; D005260:Female; D007211:Indoles / Q000737:chemistry*; D007313:Insecta / Q000235:genetics* / Q000648:ultrastructure; D007621:Karyotyping / Q000379:methods; D008297:Male; D008856:Microscopy, Fluorescence; D016622:Silver Staining / Q000379:methods
chemical_list: D007211:Indoles; C007293:DAPI; D014128:Chromomycin A3