Chromosomal painting detects non-random chromosome arrangement in dasyuridmarsupial sperm

Chromosome arrangements have been studied in metaphase and interphase somat ic cells and in sperm of many animal species, but there are conflicting dat a and it is still not clear whether chromosomes are arranged randomly or no n-randomly. We used chromosome painting to reveal the positions of chromoso mes in marsupial sperm. Marsupials are ideally suited for these studies bec ause they have only a few large chromosomes. Here, we show that chromosomes occupy fixed positions in the immature and mature sperm of Sminthopsis cra ssicaudata. We suggest that the non-random arrangement of chromosomes in ma rsupial sperm may be important in establishing chromosome arrangement and p atterns of gene activity within the developing embryo.