Projeto de pesquisa

The increment of intracellular Calcium ([Ca2+]) in the egg cytoplasm induce egg activation and blocks polyspermy (Jaffe, L.A., 2018). This increment is universal for all animals and produce conserved processes as completion of meiosis II, translation of maternal mRNAs and release of cortical granules (Burry et al., 2016). Cortical granules are excretory calcium dependent organelles, which modify the extracellular matrix of the oocyte through exocytosis. This process is called Cortical Reaction. The mechanical result of cortical reaction is to harden the outer accessory layers of the egg (Harper, J.C., 2011). Contents of cortical granules causes this hardening due to proteolytic action of many enzymes, notably by glycosidases (Wassarman, P.M., 2001). More specifically, the calcium sensor Synaptotagmin regulates cortical exocytosis helped by the activation of Ca2+/calmodulin-dependent protein kinase II (CAMKII) and myosin light chain kinase (MLCK) (Burry et al., 2016). Nonetheless is reported that these processes are universal for all animals, there is a notable exception within the ascidian egg. Ascidians prevent polyspermy by the increment of intracellular calcium and release of glycosidases, but do not have cortical granules (Gallo, A., 2016). It is not clear how the glucosidase is released but it is proposed to be mediated by subcortical acellular envelopes of the egg (Lambert, C., 1989). Strong evidence has demonstrated that different isoforms of ascidian glucosidase are present not only in the egg but also in follicular accessory cells of the egg (Koyanagi & Honegger, 2003). None of these investigations has a description, nor molecular analysis of the process of the release of glucosidase in the ascidian egg or follicular accessory cells. Preliminary results of the EVODEVO lab at USP suggest that caloric deprivation would lead to an induced infertility. These results suggest that a possible interaction between the egg and the follic