Jelly plug dissolution in <i>Discoglossus pictus</i> eggs (Anura) involves peroxidase-like activity and oxidative opening of disulphide bonds

Reactive oxygen species (ROS) and reactive nitrogen species have generally been considered as being highly reactive and cytotoxic molecules. Besides their noxious effects, ROS participate in physiological processes in a carefully regulated manner. By way of example, microbicidal ROS are produced in professional phagocytes, ROS function as short-lived messengers having a role in signal transduction and, among other processes, participate in the synthesis of the iodothyronine hormones, reproduction, apoptosis and necrosis. Because of their ability to mediate a crosstalk between key molecules, their role might be dual (at least in some cases). The levels of ROS increase from a certain age, being associated with various diseases typical of senescence. The aim of this review is to summarize the recent findings on the physiological role of ROS. Other issues addressed are an increase in ROS levels during ageing, and the possibility of the physiological nature of this process.

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“…A peroxidase activity similar to that of the sea urchin was found in the oocytes of other species (Pitari et al. 1993, Li et al.…”

Section: Fertilizationmentioning

confidence: 56%

“…A peroxidase activity similar to that of the sea urchin was found in the oocytes of other species (Pitari et al 1993, Li et al 1996, Wong et al 2004. Their defence against polyspermy also seems to be based on the dualoxidase mechanism or a similar one, and depends on a carefully regulated amount of ROS.…”

Section: Fertilizationmentioning

confidence: 71%

Reactive oxygen and nitrogen species in normal physiological processes

et al. 2009

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“…Uterine eggs were ®rst dejellied in dejellying buffer (100 mM NaCl, 5 mM DTE; 50 mM Tris±HCl pH 8.5) and then transferred into HB for manual removal of the VE. After extensive rinsing and a brief centrifugation at a low speed to pellet the envelopes, the VEs were treated with 0.6 M KI for few minutes to remove the innermost jelly layer J1 and resuspended in 1/10 Ringer (see Pitari et al, 1993).…”

Section: Preparation Of Ce and Vementioning

confidence: 99%

Following passage through the oviduct, the coelomic envelope ofDiscoglossus pictus (amphibia) acquires fertilizability upon reorganization, conversion of gp 42 to gp 40, extensive glycosylation, and formation of a specific layer

Caputo¹,

Infante²,

Talevi³

et al. 2001

Mol. Reprod. Dev.

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This paper describes the morphological and biochemical changes in Discoglossus pictus coelomic oocyte envelope (CE) following passage through the oviduct. As in other anurans, in this species, the transformation of the envelope into vitelline envelope (VE) leads to the acquisition of fertilizability and involves the cleavage of a glycoprotein. In addition, several features, typical of Discoglossus pictus, were observed. A new layer, VE‐D, forms underneath the VE region facing the site of sperm entrance, the dimple. In the VE, arrowhead‐like bundles of fibrils are perpendicularly oriented toward the dimple. Ultrastructural observations and staining with UEA‐I suggested that VE‐D might have a role in supporting sperm penetration into the dimple by orienting VE bundles and exposing sugar residues such as fucose. In ‘in vitro’ tests, VE binding of sperm occurs only if sperm are exposed to A23187, in agreement with previous data (Campanella et al., 1997: Mol Reprod Dev 47:323–333). Sperm binding occurs all over the VE. Accordingly, extracts of the VE covering the animal or the vegetal hemisphere have the same affinity to lectins (DBA, DSA, GNA, MAA, SBA, SNA, UEA‐I, WGA). The CE contains six main glycoproteins. Peptide mapping indicated that during CE transformation into VE, gp 42 shifts to an apparent Mr of 40 and gp 61 is converted to an apparent Mr of 63 kDa. Lectin blot analyses showed extensive changes in cross‐reactivity of most glycoproteins during the CE→VE transition. The fact that DBA and UEA‐I stain gp 63 rather than gp 61 and that this change is related only to gp 63, suggested that O‐glycosylation and terminal fucose might be acquired by gp 63 in preparation of fertilization. Gp 63 has recently been cloned (Vaccaro et al., submitted) and shown to exhibit high homology to Xenopus gp 69/64, a VE sperm ligand (Tian et al., 1997a: J. Cell Biol. 136: 1099–1108; Tian et al., 1997b: Dev Biol 187:143–153), and to ZP2 of mammals. Mol. Reprod. Dev. 58:318–329, 2001. © 2001 Wiley‐Liss, Inc.

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