Influences of glyphosate residues and different concentrate feed proportions in dairy cow rations during early gestation on performance, blood parameters, functional properties and DNA damage of blood cells in cows and their offspring

Effects of exposure of dairy cows to a mixture of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs), dioxin-like (dl) polychlorinated biphenyls (PCBs), and non-dl-PCBs during the period of negative and positive energy balance on health traits and on aryl hydrocarbon receptor (AHR)-signaling

This study investigated the impact of oral dioxin and PCB exposure on Holstein cows during negative (NEB) and positive (PEB) energy balance. Nine cows were divided into control (CON, n = 4) and exposed (EXP, n = 5) groups. The EXP group received 278/266 pg dioxin-like (dl)-PCB TEQ/kg BW/day and 75/72 ng non-dl-PCBs/kg BW/day for 28 days during both NEB and PEB. Inner exposure and health parameters were assessed. Cholesterol levels increased faster in the EXP group during NEB (p = 0.049). During PEB, CD4+ cell proportion and mean fluorescence intensity (MFI), along with CD8+ cell MFI, decreased in the EXP group while increasing in the CON group (p = 0.004, p = 0.05, and p = 0.023, respectively). AHR-signaling mRNA expression was unaffected in subcutaneous adipose tissue, spleen, and peripheral blood mononuclear cells. However, approximately 100 days post-exposure, hepatic AHR and ARNT mRNA expression remained elevated in the EXP group (p = 0.023 each) and correlated positively with liver dioxin and PCB residues (r2 = 0.43-0.75). Overall, dioxin and PCB effects on the examined endpoints were minor. The long-term implications of the observed T-cell and hepatic AHR-signaling changes require further investigation.

The effects of a glyphosate-based herbicide on the bovine gametes during an in vitro embryo production model

Roundup® (R), while it is the most used herbicide globally, and its residues are ubiquitous in urban and suburban areas, its impact on vertebrates' safety remains highly debated. Here, in three in vitro experiments, we investigated the effects of a very low dose (1 ppm) of R on the fertilization capacity and embryo development in cattle. In the first experiment, frozen-thawed bull semen exposed to R for 1 h exhibited reduced motility parameters but unaffected fertilization ability. However, after in vitro fertilization, the rates of embryo formation were significantly lower compared to the untreated controls. In the second experiment, oocytes exposed to R during in vitro maturation showed reduced cleavage rates, and the embryo yield on days 7, 8, and 9 of embryo culture was significantly lower than that of the controls. In the third experiment, oocytes were matured in the presence of R and in a medium containing both R and Zinc, chosen to offer antioxidant protection to the oocytes. Day-7 blastocysts were analyzed for the expression of genes associated with oxidative stress, apoptosis, and epigenetic reprogramming. Exposure to R markedly suppressed embryo formation rates compared to the controls. The combination of R with Zinc restored the blastocyst yield, which on days 8 and 9 was comparable to that of the controls and higher than the groups exposed only to R on all days. The gene expression analysis revealed that R promotes oxidative stress development, triggers apoptosis, and induces epigenetic changes in developing embryos, while zinc presence alleviates these adverse effects of R. These findings imply that even at very low doses, R could be highly toxic, leading to functional abnormalities in both gametes, potentially affecting fertility in both genders.

Glyphosate resistance and biodegradation by Burkholderia cenocepacia CEIB S5-2

Glyphosate is a broad spectrum and non-selective herbicide employed to control different weeds in agricultural and urban zones and to facilitate the harvest of various crops. Currently, glyphosate-based formulations are the most employed herbicides in agriculture worldwide. Extensive use of glyphosate has been related to environmental pollution events and adverse effects on non-target organisms, including humans. Reducing the presence of glyphosate in the environment and its potential adverse effects requires the development of remediation and treatment alternatives. Bioremediation with microorganisms has been proposed as a feasible alternative for treating glyphosate pollution. The present study reports the glyphosate resistance profile and degradation capacity of the bacterial strain Burkholderia cenocepacia CEIB S5-2, isolated from an agricultural field in Morelos-México. According to the agar plates and the liquid media inhibition assays, the bacterial strain can resist glyphosate exposure at high concentrations, 2000 mg·L-1. In the degradation assays, the bacterial strain was capable of fast degrading glyphosate (50 mg·L-1) and the primary degradation metabolite aminomethylphosphonic acid (AMPA) in just eight hours. The analysis of the genomic data of B. cenocepacia CEIB S5-2 revealed the presence of genes that encode enzymes implicated in glyphosate biodegradation through the two metabolic pathways reported, sarcosine and AMPA. This investigation provides novel information about the potential of species of the genus Burkholderia in the degradation of the herbicide glyphosate and its main degradation metabolite (AMPA). Furthermore, the analysis of genomic information allowed us to propose for the first time a metabolic route related to the degradation of glyphosate in this bacterial group. According to the findings of this study, B. cenocepacia CEIB S5-2 displays a great glyphosate biodegradation capability and has the potential to be implemented in glyphosate bioremediation approaches.