Effect of environmental contamination on female and male gametes – A lesson from bovines

Abstract

Endocrine-disrupting compounds (EDCs) and foodborne contaminants are environmental pollutants that are considered reproductive toxicants due to their deleterious effects on female and male gametes. Among the EDCs, the phthalate plasticizers are of growing concern. In-vivo and in-vitro models indicate that the oocyte is highly sensitive to phthalates. This review summarizes the effects of di(2-ethylhexyl) phthalate and its major metabolite mono(2-ethyhexyl) phthalate (MEHP) on the oocyte. MEHP reduces the proportion of oocytes that fertilize, cleave and develop to the blastocyst stage. This is associated with negative effects on meiotic progression, and disruption of cortical granules, endoplasmic reticulum and mitochondrial reorganization. MEHP alters mitochondrial membrane polarity, increases reactive oxygen species levels and induces alterations in genes associated with oxidative phosphorylation. A carryover effect from the oocyte to the blastocyst is manifested by alterations in the transcriptomic profile of blastocysts developed from MEHP-treated oocytes. Among foodborne contaminants, the pesticide atrazine (ATZ) and the mycotoxin aflatoxin B1 (AFB1) are of high concern. The potential hazards associated with exposure of spermatozoa to these contaminants and their carryover effect to the blastocyst are described. AFB1 and ATZ reduce spermatozoa's viability, as reflected by a high proportion of cells with damaged plasma membrane; induce acrosome reaction, expressed as damage to the acrosomal membrane; and interfere with mitochondrial function, characterized by hyperpolarization of the membrane. ATZ and AFB1-treated spermatozoa show a high proportion of cells with fragmented DNA. Exposure of spermatozoa to AFB1 and ATZ reduces fertilization and cleavage rates, but not that of blastocyst formation. However, fertilization with AFB1-or ATZ-treated spermatozoa impairs transcript expression in the formed blastocysts, implying a carryover effect. Taken together, the review indicates the risk of exposing farm animals to environmental contaminants, and their deleterious effects on female and male gametes and the developing embryo.

Actions of CSF2 and DKK1 on bovine embryo development and pregnancy outcomes are affected by composition of embryo culture medium

“…Such a phenomenon was observed in the present experiment, where cleaved embryos produced using semen from sire 1 being less likely to become blastocysts than embryos from sire 2. Effects of sire on development could represent inheritance of paternal alleles by the embryo that are detrimental to embryonic development 32 , 33 , 44 or environmental effects during spermatogenesis 45 , 46 or after ejaculation 47 , 48 that affect sperm function.…”

One Health challenges for pig reproduction

“…Approximately 1000 human‐derived chemicals are classified as EDCs, and their effects are often synergistic and cumulative, and may carry over to following generations. Several recent reviews have explored this subject (Graceli et al, 2020; Komsky‐Elbaz et al, 2021; Laws et al, 2021; Repouskou et al, 2021; Roth et al, 2020; Sedha et al, 2021; Weaver et al, 2020; Zhang et al, 2021). In this section, the sources of exposure and the effects on human and animal reproduction of EDCs and certain heavy metals are discussed.…”

Female Germ Cell Development, Functioning and Associated Adversities under Unfavorable Circumstances

“…Offspring produced from cyclophosphamide exposed mice showed high incidence of TGCT and reduced testicular and epididymal sperm count whereas primordial follicle loss and increased follicular growth activation was observed in female offspring. Endocrine disrupting compounds (EDCs) represents another category of reproductive toxicants which produces deleterious effects on male and female gametes by interfering natural hormone activities and other associated developmental processes [ 52 ]. Women (at different reproductive life stages) exposed to environmental di(2-ethylhexyl) phthalate (DEHP) and its metabolites were shown to have impaired reproduction and reduced fertility.…”