Insect sex chromosomes. VIII. Identification of active/inactive X-chromosomes in Gryllotalpa fossor by 5-BrdU/AO fluorescence.

By employing 5-BrdU/AO fluorescence technique to distinguish active from inactive X-chromosomes, we have, for the first time, provided evidence in support of the validity of this technique for a non-mammalian system Gryllotalpa fossor (Orthoptera). In the female somatic cells of Gryllotalpa, it is only in the active (euchromatic) arm of X-chromosome that the fluorescence is bright, whereas it is dull in the facultative and constitutive heterochromatic arms. In tetraploid spermatogonial cells one of the two X-chromosomes is inactive, suggesting that this phenomenon is probably a random one and that the inactivation process is independent of the imprinting mechanism.