An introduction to the issue of acatalasia

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An introduction to the issue of acatalasia

Advanced Search Abstract The balanced presence of reactive oxygen species and antioxidants has a positive impact on sperm functions, oocyte maturation, fertilization, and embryo development in vitro. The mammalian oviduct is likely to provide an optimal environment for final gamete maturation, sperm-egg fusion, and early embryonic development.

However, the expression and distribution of antioxidant enzymes in the bovine oviduct are poorly characterized. We analyzed the mRNA expression and enzymatic activities of major antioxidants glutathione peroxidase GPxsuperoxide dismutase Cu,ZnSODand catalase in the bovine oviduct throughout the estrous cycle.

The high levels of expression for GPx-3 in the isthmus were in contrast to expression of GPx-1 and GPx-2, which occurred mostly in the ampulla and infundibulum of the oviduct.

The highest levels of mRNA expression for GPx-1 were observed toward the end of the estrous cycle before ovulation, whereas GPx-2 was mostly expressed at midcycle. The highest levels of glutathione and enzymatic activities for GPx and catalase occurred at the middle 10—12 days and end 18—20 days of the estrous cycle, whereas total SOD activity remained constant throughout the estrous cycle in the oviductal fluids.

These findings underscore the importance of hydrogen peroxide and hydroperoxide removal by GPx in the oviduct. The heterogeneous expression of antioxidants such as GPx along the oviduct is a possible indication of their physiological role in the events leading to successful fertilization and implantation in vivo.

Introduction Successful fertilization and implantation rely on complex and progressive interactions among the maternal genital tract, gametes, and fertilized oocytes. The oviducts function as a sperm reservoir, a site of male gamete selection, and a site of fertilization in cows and other species [ 1 — 4 ].

Although reactive oxygen species ROS: H2O2 blocks the motility of bovine sperm in vitro [ 1112 ], and ROS decrease sperm-oocyte penetration and block sperm-egg fusion in mice [ 13 ]. However, binding of sperm to the zona pellucida is promoted by low levels of ROS and is inhibited by antioxidants [ 14 ].

Thus, the way the female tract controls the generation of ROS could be a determining factor in successful fertilization and subsequent implantation. ROS generation is controlled by enzymatic and nonenzymatic processes. The main enzymatic defenses against H2O2 include classic catalase, oviductal fluid catalase, and the family of glutathione peroxidases GPxwhich comprises five members [ 17 — 19 ].

GPx are able to metabolize H2O2 and lipid hydroperoxides. The main intracellular form of GPx is classic glutathione peroxidase or GPx-1 [ 18 ]. GPx-2 is mainly found in the gastrointestinal tract [ 22 ], and expression of GPx-4 and GPx-5 has been reported in the testis and the epididymis, respectively [ 2324 ].

Other enzymes, such as the glutathione-S-transferases GSThave peroxydatic activities similar to those of GPx [ 15 ]. The major antioxidants that control in vivo ROS levels in the oviduct remain to be characterized in cows and other species.

A catalase in the bovine oviduct binds specifically to spermatozoa [ 26 ]. Many proteins are glycosylated [ 2930 ].

Certain proteins, such as a kDa protein, are regulated by the ovarian cycle [ 3132 ].

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We characterized the mRNA expression of major antioxidant enzymes in the oviduct throughout the estrous cycle of the cow. The oviduct was divided into six equal sections for a better localization of the expression. We also measured the main antioxidant enzymatic activities in the oviductal fluid and found that the highest levels occurred before ovulation.

Materials and Methods Oviducts Bovine oviducts were transported on ice from the slaughterhouse to the laboratory within 4 h. After examination by a veterinarian, animals showing genital tract anomalies were rejected according to the criteria documented by Arosh et al.On another note, global warming is an issue that is having effects on almost all aspects of our environment.

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Acatalasia is an autosomal recessive peroxisomal disorder caused by absent or very low levels of the enzyme catalase.

Catalase breaks down hydrogen peroxide in cells into water and oxygen. Low levels of catalase can cause hydrogen peroxide to build up, causing damage to cells.

An introduction to the issue of acatalasia
OMIM Entry - # - ACATALASEMIA