Fig. 1.

Examples of plant and animal species possessing B chromosomes. a The Bs in rye (Secale cereale). Arrowed Bs showing cross-hybridization with the B-specific repeat ScCl11 (red), Sc36c82 (green), and D1100 (yellow). (Picture provided by A. Marques, Gatersleben, Germany.) b The micro and standard Bs (arrowed) in Brachycome dichromosomatica. Metaphase chromosomes showing cross-hybridization with 45S rDNA (green). c The Bs (arrowed) in Crepis capillaris. Metaphase chromosomes showing cross-hybridization with 45S rDNA (red) and Arabidopsis-type telomere probes (green) probe obtained from microdissected Bs. d The Bs in Korean field mouse (Apodemus peninsulae): two-color FISH of microdissected DNA probes derived from centromeric C-positive region of autosome (red) and from C-negative region of the arm of one of the Bs (green) with metaphase chromosomes of specimens containing 18 Bs. Arrows indicate the dot-like Bs; sex chromosomes are marked with X and Y. (Picture provided by N.B. Rubtsov, Novosibirsk, Russia.) e The Bs in migratory locust (Locusta migratoria). Mitotic metaphase from a female embryo showing cross-hybridization with a DNA probe obtained from microdissected Bs. Note the intense painting of the B chromosomes (arrowed) and the pericentromeric regions of several of the 24 A chromosomes. (Picture provided by J.P.M. Camacho, Granada, Spain.) f The Bs in rye (Secale cereale). Arrowed Bs showing cross-hybridization with mitochondrial DNA (blue), plastid DNA (green) and the B-specific D1100 repeat (yellow). Insets show Bs after hybridization with (f′) plastid DNA (green) or (f″) mitochondrial DNA (blue). Note that only 12 of 14 A chromosomes are shown