Drosophila oocytes as a model for understanding meiosis: an educational primer to accompany "corolla is a novel protein that contributes to the architecture of the synaptonemal complex of Drosophila"

Abstract

Achieving a thorough understanding of the events and ramifications of meiosis is a common learning objective for undergraduate introductory biology, genetics, and cell biology courses. Meiosis is also one of the most challenging cellular processes for students to conceptualize. Connecting textbook descriptions of meiosis to current research in the field of genetics in a problem-based learning format may aid students' understanding of this important biological concept. This primer seeks to assist students and instructors by providing an introductory framework upon which to integrate discussions of current meiosis research into traditional genetics or cell biology curriculum.

Keywords: Drosophila; education; meiosis; oocyte.

Figure 1

Balancer chromosomes allow for the maintenance of lethal mutant alleles. (A) Schematic representation of a balancer chromosome (blue) compared to a wild type chromosome (red). Numbers below represent regions of the chromosome. The balancer chromosome contains many inverted segments that effectively suppress meiotic recombination, and carries a visible dominant mutation (CyO). (B) Punnet square in which flies heterozygous for an allele of a gene of interest (Gene^x) and the balancer are mated. Phenotypes resulting from the presence or absence of the balancer are highlighted in red.

Figure 2

Schematic diagrams of the Drosophila ovary. (A and B) Each female fruitfly has a pair of ovaries (A), each consisting of 15–20 ovarioles, composed of progressively more developed follicles (B). (C) A 1-µm optical cross-section of an ovariole (most mature stages have been removed); germ cells (green) labeled with antivasa, niche, and follicle cell membranes (red) labeled with anti-Hts and anti-LamC, and nuclei (blue) labeled with DAPI. fc, follicle cells; nc, nurse cells; oo, oocyte. Bar, 50 µm. (D and E) The germarium (D) is composed of germline stem cells (pink) in their niche (terminal filament, cap, and escort cells; blue). Daughters of the germline stem cells (peach) divide to form a cyst (E); the pro-oocytes (gray) initiate SC formation in zygotene of prophase I. Follicle cells (light green), daughters of follicle stem cells (dark green), encapsulate the cyst at the posterior of the germarium.

Figure 3

Schematic diagram of the synaptonemal complex, modeled after Lake and Hawley (2012). See text for description.