| orientation of nonrandomly segregating sex chromosomes in spermatocytes of the flea beetle, alagoasa bicolor l. | in males of the flea beetle, alagoasa bicolor l., spermatocytes have two achiasmate sex chromosomes, x and y, each of which is approximately five times larger than the ten pairs of chiasmate autosomes. at metaphase i, these univalent sex chromosomes are located on a spindle domain separated from the autosomal spindle domain by a sheath of mitochondria. a single centriole pair is located at each pole of the spindle. in prometaphase i, each sex chromosome appears to maintain an attachment to both ... | 2001 | 11398974 |
| behavior of sex chromosomes, autosomes, and the spindle during nonrandom segregation in a flea beetle. | we have analyzed autosome, sex chromosome, and spindle behavior in spermatocytes of the flea beetle, alagoasa bicolor. in this species, males have very large x and y chromosomes, which, although they are never physically connected, always segregate to opposite spindle poles at anaphase i, thus preserving the sex ratio in the next generation. we find that the sex chromosomes are partitioned to a peripheral spindle domain early in prometaphase i and that their segregation can be accounted for main ... | 2000 | 10902717 |
| the pattern of sex chromosome kinetochore phosphorylation during nonrandom segregation in a flea beetle. | in the flea beetle species, alagoasa bicolor, males have two sex chromosomes, x and y, each of which is larger than the rest of the genome combined. these large sex chromosomes do not pair at meiosis i, and are therefore not joined at metaphase i. nevertheless, they always segregate from each other at anaphase i. as prometaphase i progresses, the unpaired x and y undergo reorientation from a parallel to a linear configuration. using 3f3/2, an antibody that detects the level of phosphorylation of ... | 2000 | 10874470 |