title: Chromosomal study of a lamprey (Lampetra zanandreai Vladykov, 1955) (Petromyzonida: Petromyzontiformes): conventional and FISH analysis.
abstract: Karyotype and other chromosomal characteristics in the Adriatic brook lamprey Lampetra zanandreai, representative of one of the most ancestral group of vertebrates, were examined using conventional (Ag-staining, C-banding as well as CMA(3) and DAPI fluorescence) and molecular (FISH with 18/28S rDNA and EcoRI satDNA as probes) protocols with metaphase chromosomes derived from whole blood cultures. The chromosome complement had a modal diploid chromosome number of 2n = 164, as in other petromyzontid lamprey species. Ag-staining and CMA(3) fluorescence, as well as FISH with 18/28S rDNA probes, detected nucleolar organizer regions (NORs) close to the centromeres of the biarmed chromosomes of pairs 1 and 2, the largest chromosome pairs of the complement. In addition to NORs, CMA(3) fluorescence revealed positive signals in approximately 40 other chromosomes. DAPI stained mostly centromeric regions of many chromosomes as well as conspicuously massive blocks overlapping NOR sites. C-banding evidenced a large amount of constitutive heterochromatin in somatic chromosomes, with approximately 40 C-positive acrocentric elements completely heterochromatic, corresponding with the 40 CMA(3)+ chromosomes and positive heterochromatic blocks in pericentromeric regions of chromosome pairs 1 and 2. Polymerase chain reaction (PCR)-based cloning of satellite DNA with primers derived from Petromyzon marinus centromeric sequences was successful for L. zanandreai genomic DNA. The sequence was AT-rich (59%) and characterized by short consensus motifs similar to other centromeric satellite motifs. FISH using satDNA clones as a probe produced a fluorescent signal on a single pair of small chromosomes. This sequence was PCR-amplified also in L. planeri and P. marinus genomic DNA, and the evolution of this repetitive element in the above species was analysed.
authors: Dipartimento di Biochimica, Biologia e Genetica, Università Politecnica delle Marche, via Ranieri, 65, 60100, Ancona, Italy. v.caputo@univpm.it
authors: Vincenzo
authors: V
authors: Caputo
authors: Massimo
authors: M
authors: Giovannotti
authors: Paola Nisi
authors: PN
authors: Cerioni
authors: Andrea
authors: A
authors: Splendiani
authors: James
authors: J
authors: Tagliavini
authors: Ettore
authors: E
authors: Olmo
mesh_terms: D000818:Animals; D001483:Base Sequence; D002503:Centromere / Q000378:metabolism; D002871:Chromosome Banding; D002875:Chromosomes / Q000235:genetics*; D016000:Cluster Analysis; D004276:DNA, Satellite / Q000235:genetics; D004171:Diploidy; D005260:Female; D006570:Heterochromatin / Q000378:metabolism; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D007798:Lampreys / Q000235:genetics*; D008297:Male; D008969:Molecular Sequence Data; D009697:Nucleolus Organizer Region / Q000235:genetics; D016415:Sequence Alignment
chemical_list: D004276:DNA, Satellite; D006570:Heterochromatin