GENETICS AND CYTOLOGY OF T(7-9) 1-9 - RECIPROCAL TRANSLOCATION IN THEGERMAN-COCKROACH (DICTYOPTERA, BLATTELLIDAE)/

Cytology and genetics of T(7;9)/7;9, a translocation of tile German co ckroach, Blattella germanica (L.), are described. T(7;9)/7;9 is closel y linked with ruby eye (ru) on chromosome 9 and orange body, (or) on c hromosome 7, but distantly linked with a 2nd chromosome 7 marker, whit e eye (w). The or locus and the chromosome 7 breakpoint lie close to t he metacentric chromosome 7 centromere. The order of chromosome 7 loci is breakpoint-or-w. An increase in recombination between or and w in test crosses with T(7;9)/7;9 is attributed to a shift from a terminal or near terminal position of one chiasma to a strongly subterminal pos ition, placing it between the w, and or loci. The frequency of adjacen t disjunction and ring breakup were affected by genotype. Chromosome 7 breakpoints and other characteristics of T(7;9)/7;9 are compared with those of T(7;12)/7;12.