Beauvericin (BEA) is a mycotoxin produced by several Fusarium species and a common contaminant of food and feed. Due to its ionophoric properties it can disturb mitochondrial function, and enhance reactive oxygen species (ROS) production and membrane lipid peroxidation [1]. It has been reported that BEA may affect the quality of oocytes by reducing granulosa cell function in pigs [1]. Here we determined the effect of BEA on meiotic competence and cytoplasmic maturation of oocytes from pre-pubertal sheep. Cumulusoocyte complexes (COCs) recovered at local slaughterhouses from the ovaries of sheep younger than 6 months were underwent in vitro maturation (IVM) [2]. COCs were exposed to BEA concentrations selected on the basis of previous studies (0.5, 1, 3, 5 μM) [3]. COCs cultured in IVM medium with 0.02% DMSO (vehicle) were used as controls. After IVM, cumulus cells were removed and oocytes stained with MitoTracker Orange CMTM Ros, 2′,7′- dichlorodihydrofluorescein diacetate and Hoechst 33258 and fixed in 2% paraformaldehyde in PBS. Oocytes at the metaphase II stage were analyzed by confocal laser scanning microscopy for their cytoplasmic maturation expressed as mitochondria (mt) distribution pattern [2]. Data were analysed by Chi-square test and differences were considered to be significant when P<0.05. A total of 464 oocytes were analyzed in four replicates. BEA, at 5 μM, was found to reduce the maturation rate (45/94, 47.9% vs 59/93, 63.4%, for exposed and controls, respectively; P<0.05) whereas it was not effective at the lower tested concentrations (58/94, 61.7%; 45/93, 48.4%; 47/90, 52.2% for 0.5, 1 and 3 μM, respectively; P>0.05). In addition, BEA at 5 μM affected the bioenergetic status of oocytes, as it increased the rate of oocytes showing abnormal mt pattern (5/45, 11% vs 0/59, 0%, for exposed and controls, respectively; P<0.05) and reduced the rate of oocytes with healthy perinuclear/pericortical mt pattern (20/45, 44% vs 39/59, 66%, for exposed and controls, respectively; P<0.05). No effects were noticed on mt pattern at lower tested concentrations (37/58, 64%; 25/45, 56%; 29/47, 62%, for 0.5, 1 and 3 μM respectively; P>0.05). These data indicate that BEA, in the exposure conditions used in the present study, hinder nuclear and cytoplasmic maturation in prepubertal sheep oocytes.
BEAUVERICIN DISTURBS NUCLEAR AND CYTOPLASMIC MATURATION OF PREBUPERTAL SHEEP OOCYTES
Mastrorocco A;
2018-01-01
Abstract
Beauvericin (BEA) is a mycotoxin produced by several Fusarium species and a common contaminant of food and feed. Due to its ionophoric properties it can disturb mitochondrial function, and enhance reactive oxygen species (ROS) production and membrane lipid peroxidation [1]. It has been reported that BEA may affect the quality of oocytes by reducing granulosa cell function in pigs [1]. Here we determined the effect of BEA on meiotic competence and cytoplasmic maturation of oocytes from pre-pubertal sheep. Cumulusoocyte complexes (COCs) recovered at local slaughterhouses from the ovaries of sheep younger than 6 months were underwent in vitro maturation (IVM) [2]. COCs were exposed to BEA concentrations selected on the basis of previous studies (0.5, 1, 3, 5 μM) [3]. COCs cultured in IVM medium with 0.02% DMSO (vehicle) were used as controls. After IVM, cumulus cells were removed and oocytes stained with MitoTracker Orange CMTM Ros, 2′,7′- dichlorodihydrofluorescein diacetate and Hoechst 33258 and fixed in 2% paraformaldehyde in PBS. Oocytes at the metaphase II stage were analyzed by confocal laser scanning microscopy for their cytoplasmic maturation expressed as mitochondria (mt) distribution pattern [2]. Data were analysed by Chi-square test and differences were considered to be significant when P<0.05. A total of 464 oocytes were analyzed in four replicates. BEA, at 5 μM, was found to reduce the maturation rate (45/94, 47.9% vs 59/93, 63.4%, for exposed and controls, respectively; P<0.05) whereas it was not effective at the lower tested concentrations (58/94, 61.7%; 45/93, 48.4%; 47/90, 52.2% for 0.5, 1 and 3 μM, respectively; P>0.05). In addition, BEA at 5 μM affected the bioenergetic status of oocytes, as it increased the rate of oocytes showing abnormal mt pattern (5/45, 11% vs 0/59, 0%, for exposed and controls, respectively; P<0.05) and reduced the rate of oocytes with healthy perinuclear/pericortical mt pattern (20/45, 44% vs 39/59, 66%, for exposed and controls, respectively; P<0.05). No effects were noticed on mt pattern at lower tested concentrations (37/58, 64%; 25/45, 56%; 29/47, 62%, for 0.5, 1 and 3 μM respectively; P>0.05). These data indicate that BEA, in the exposure conditions used in the present study, hinder nuclear and cytoplasmic maturation in prepubertal sheep oocytes.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
