Syngamy and Cell Cycle Control

Abstract

The key aspect of sexual reproduction is the generation of genetic variation through the swapping of variable lengths of chromosome arms between pairs of homologous chromosomes during meiotic recombination in the germline. Following recombination, it is the general rule that a single (haploid) set of chromosomes is packaged into each male and female gamete (sperm and egg). These two sets of chromosomes, one from each parent, then come together to form a single nucleus: the process of syngamy. This simple outcome is achieved in a complex way through the process of fertilization. Fertilization comprises the delivery of the male set of chromosomes, tightly packaged in a small and motile sperm, to the female set of chromosomes, contained within a much larger nutrient laden and relatively sessile egg or oocyte; at fertilization, fusion of the two gametes occurs as a prelude to syngamy. In addition, fertilization triggers the onset of the very rapid rounds of cell division that quickly produce a very large number of embryonic cells. The cell division cycle must be coordinated with the events of syngamy. Large intracellular calcium signals occur at fertilization and ensure that the events of the cell cycle are controlled to permit successful melding of the parents' genomes. Keywords: Actin; Allosteric; Apoptosis; Centromeres; Chaperones; Chromatin; Cyclic AMP; Cytokinesis; Depolarization; Disjunction; Echinoderms; Enzymes; Glycoprotein; Histones; Homologs; Hydrophobic; Imprinting; Interphase; Introns; Kinases; Lipid bilayers; Microtubules; Mitosis; NADPH; Phospholipases; Polyamines; Polymorphism; Proteoglycans; Proteolysis; S-phase; Spindle; Sympatric; Vesicles