Segregation of the Univalent X Chromosome in the Two-striped Planthopper Acanalonia bivittata
Author:
Ashley Borseth (Graduate Student)Co-Authors:
Kristen D. Felt, Emily L. Stowe, Leocadia V. PaliulisFaculty Mentor(s):
Dr. Leocadia PaliulisFunding Source:
Graduate Summer Research Award, Biology DepartmentAbstract
Correct segregation in meiosis I depends on homologous chromosomes pairing to form bivalents. To achieve a successful reduction in ploidy, bivalents align on the metaphase plate and then homologues segregate during anaphase I. While bivalent formation is generally required for correct segregation in meiosis I, many organisms pose an exception to this requirement. Our objective was to study one such exception, the two-striped planthopper Acanalonia bivittata (Hemiptera, Auchenorrhyncha), which has a univalent X chromosome. A. bivittata were collected and their identification was confirmed through DNA barcoding. Chromosome number was found to be consistent with previously published karyotypes for the species. To observe the behavior of unpaired chromosomes in male primary spermatocytes, live-cell and confocal imaging of stained cells was conducted. The univalent X chromosomes were found to be characterized by independent and delayed segregation that occurred after autosomal segregation during early anaphase I. Delayed segregation of the univalent chromosome was associated with the loss of microtubule connections to one spindle pole, leaving the chromosome aligned on the metaphase plate, often in a position outside the main spindle body. This study characterized the behavior of an unpaired chromosome in an alteration to the traditional meiotic program. This work has translational implications in organisms in which a chromosomal pairing partner is lost, such as the diminution and potential loss of a Y chromosome in mammals.