Glutathione and its related enzymes in the gonad of Nile Tilapia (Oreochromis niloticus)

Abstract

Glutathione (GSH) concentration, the activity of its metabolizing enzymes, glutathione transferase (GST), glutathione peroxidase (GPx), glutathione reductase (GR), and the antioxidant enzyme catalase (CAT) in O. niloticus ovary and testis were examined. GSH concentration of O. niloticus testis exhibited high concentration (129 ± 21 nmol/g tissue) compared with GSH concentration (49.2 ± 8.3 nmol/g tissue) in the ovary. GST, GPx, GR, and CAT activities of O. niloticus testis exhibited high values compared with their corresponding values in ovary homogenates. However, protein concentration in ovary homogenates exhibited higher values (175 ± 40.6 mg) compared with testis homogenates (27.1 ± 3.7 mg). O. niloticus ovary was less effective in excretion of xenobiotices compared with the testis, where its function is mainly in increasing the protein content of the eggs; however, in O. niloticus testis, the glutathione cycle operated in accelerated way in the direction of reduced GSH production in order to protect the maturation stages in a save way. A simple reproducible procedure for the purification of GST from O. niloticus ovary was established. The enzymes proved to be homogenous as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and its molecular weight was calculated to be 25.1 kDa. GST of O. niloticus ovary exhibited maximum activity at pH 7.5. The Michaelis-Menten constant (K(m)) of the purified ovary GST for GSH and CDNB was 0.076 mM and 1.0 mM, respectively. Cibacron blue was the most potent inhibitor of ovary GST activity (IC50 value, concentration of inhibitor that will give 50% inhibition, equal 0.002 μM). The specific activity of GST toward different electrophilic substrates was determined. GST activity toward benzyl isothiocyanate was the highest compared with phenethyl isothiocyanate and allyl isothiocyanate.

Impression of Various Water Reserves on Reproductive Performance of the Nile Tilapia “Oreochromis niloticus”

“…The seasonal investigations of both females and males GSI organized as the highest values were in spring, followed by summer, while the lowest female GSI values were in winter, and in autumn for males. Such results are in accordance with those of many studies (Njiru et al, 2006;Shalaby & Migeed, 2012;Hamed et al, 2016;Khallaf et al, 2020). This study also agrees with El-Kasheif et al (2013) and Khallaf et al (2020) concerning the fact that the female Nile tilapia individuals have higher value of GSI than males at constant age, length and season; besides, the seasonal variations of both O. niloticus sexes following nearly the same trend.…”

A multibiomarker approach to investigate paracetamol effects in the reproduction regulatory axis of a male Neotropical catfish Rhamdia quelen

“…Unlike the hepatic tissue, the gonadal tissue showed alterations of the enzyme activity of the biotransformation system (GST) and the antioxidant system (SOD and GPx) after 14 days of exposure. These results are differently than expected, since the enzyme activities changes in this tissue are more difficult to detect than in the liver (Hamed et al, 2016). In this case, there was a reduction in GST and GPx activities at 25 µg.L -1 .…”

Correlation of testicular melatonin and cellular stress in an annual spermatogenic cycle of Clarias batrachus

“…This may be due to abundant GSH was crucial to the maturation of spermatozoa and its protection against oxidative stress. The suggested hypothesis also evidenced in an experiment on Oreochromis niloticus, showed that protection of sperm was con rmed by more GSH production in testis (Hamed et al 2016). Further, addition of 0.1mM melatonin signi cantly decreased H 2 O 2 (100 µM)-induced oxidative damage by the elevation in GSH content and activities of SOD, CAT and GPx in rabbit sperm (Zhu et al…”