Approximately 15% of eukaryotes contain supernumerary B chromosomes. When present, B chromosomes frequently represent as much as 5% of the genome. Despite thousands of reports describing the distribution of supernumeraries in various taxa, a comprehensive theory for the origin, maintenance, and evolution of B chromosomes has not emerged. Here, we sequence the complete genomes of individual cich...

Backcrossed chromosome substitution lines (CS-B) have been developed with a homologous pair of chromosomes or chromosome arms of Gossypium barbadense (3-79) germplasm substituted for the homologous Gossypium hirsutum (TM-1) chromosomes or chromosome segments. We report on agronomic and fibre trait performance of four backcrossed chromosome or chromosome arm substitution lines including chromoso...

The presence of delta is always accompanied by a sensitive second chromosome in Drosophila melanogaster or vice versa. The separability of delta and the chromosome line was investigated in experiments designed to eliminate delta or to suppress its multiplication for a number of generations. Cy/S(b)-5 males which transmit a minute amount of delta b (retained by chromosome S(b), kills S(b)/S(b) a...

Multiple copies of B chromosomes in maize (Zea mays) can accumulate in the genome using the B chromosome's accumulation mechanism, specifically nondisjunction at the second pollen mitosis and preferential fertilization of the egg. Using this mechanism, we accumulated 4 different-sized minichromosomes derived from the B chromosome to test the chromosome limits of the cell. The accumulation of no...

The two sperm cells of common origin within the pollen tube of flowering plants are each involved in a fertilization event. It has long been recognized that preferential fusion of one sperm with the egg can occur in B chromosome-containing lines of maize. If the second pollen mitosis begins with a single B chromosome, nondisjunction will result in one sperm possessing two B chromosomes and the ...