MPs were detected in bovine follicular fluid.

In (a), an example of an imaged membrane (bFF3) that was used in the software Particle Scout to determine the number of particles and their sizes and for subsequent spectra match using the software TrueMatch is shown. Particles shown in green represent all counted particles, while those shown in red represent particles for which the spectra match had a hit quality index (HQI)≥ 75. In (b) examples of particles from bFF3 with their Raman spectra (red) and the matched Raman spectra of the corresponding plastic polymer (blue) from the ST Japan and/or SLoPP database. Particle number, polymer name and HQI are shown. In (c) the composition of MPs detected in the follicular fluid of humans (Hum) and bovine (Bov) by confocal Raman spectroscopy are shown. In (d) the counts of the different plastic and non-plastic analysed particles present in each sample are shown; written are the concentration of plastic polymers for each group and water controls. The number of MPs in FF in (c and d) was adjusted to the number of particles detected in their respective water control. PP = polypropylene, PTFE = polytetrafluoroethylene, PVC = polyvinylchloride, PS = polystyrene.

Differentially abundant proteins in oocytes incubated with or without polystyrene MPs.

Protein name and ID, gene name, fold change and adjusted P-value are shown for oocytes incubated with 0.3 μm polystyrene beads compared to control and oocytes incubated with 1.1 μm polystyrene beads compared to the control. The full list of identified differentially abundant proteins is available in Data S2.

Polystyrene MPs negatively influenced oocyte maturation. The boxplots in (a) show the effects of 24 h exposure to 0.3 and 1.1 μm polystyrene beads on oocyte maturation in vitro. Image examples of each stage characterization below the panel, oocytes were stained for DNA (Hoechst33342, blue). The scatter plot in (b) depicts the first two dimensions of a principal component analysis (PCA) across the proximity matrix of a random forest model classifying oocytes exposed to 0.3 or 1.1 μm polystyrene beads versus the control, based on protein abundance profiles. Volcano plots depicting differently abundant proteins between oocytes incubated for 24 h in the presence of (c) 0.3 μm and (d) 1.1 μm polystyrene beads compared to a control are also shown.

Summary of the effects of polystyrene MP on oocyte proteomes. Differentially expressed proteins in oocytes incubated for 24 h with 0.3 (yellow) and 1.1 (green) μm polystyrene beads compared to control are shown. Proteins were found to regulate major pathways in oocyte function, such as apoptosis, mitochondrial damage, mitochondrial apoptosis, microtubule disorganization, organelle disorganization, spindle disorganization and nuclear maturation. Moreover, proteins part of response to oxidative stress and DNA damage were also differently expressed. Figure made using BioRender.