Bewildering Bs – An impression of the 1st B-chromosome conference

Beukeboom, LW,  Heredity,  73:328-336. 1994.

Ever since their first discovery B chromosomes have attracted attention. Why are they so appealing? The standard chromosomes of an organism are A chromosomes; B chromosomes are extra to this normal complement. In the B chromosome ‘bible’ (Jones & Rees, 1982) Bs are defined as dispensable supernumerary chromosomes that are not homologous and do not pair with A chromosomes. They have been further characterized as (1) morphologically different from As (usually smaller), (2) being inherited in a nonMendelian fashion, (3) not (or only rarely) having nucleolus organisers, (4) often displaying nondisjunction at anaphase of mitosis resulting in frequencies varying between organs in the same individual, (5) reducing fertility and growth when present in high numbers, and (6) carrying no genes with major effects. These features of Bs were recently discussed at an international conference and the main ideas presented by the participants are reported here. From 21 to 25 September 19