Analysis of survival and morphometric parameters of loach embryos and prelarvae under the action of the polyethyleneglycol derivative polymeric nanocarrier

Abstract

Background. Our previous studies have shown a minor embryotoxic effect of polymeric poly(VEP-co-GMA)-graft-mPEG carrier on Missgurnus fossilis L. embryos and prelarvae. At the same time, it was found that a 3-day exposure to 10-15 M polymer carrier slowed developing, which is characterized by a delayed hatching of larvae. However, in the 10-day experiment on loach larvae exposed to polymeric carrier, anomalies and defects of development have not been identified. The aim of this work was to analyze the embryos and prelarvae survival, as well as determine the morphometric indicators of the loach embryos under the action of a PEG-modified polymer carrier. Materials and Methods. Ovulation in loach females (Misgurnus fossilis L.) was stimulated by intramuscular injection of female chorionic gonadotropin (500 units), eggs were obtained 36 h after stimulation, fertilized in Petri dishes with a suspension of sperm according to A. A. Neifach. The stages of development were observed visually under a binocular microscope MBS-9 with a photo camera in a real-time mode. The experimental embryos were incubated in Goltfreter’s solution with the addition of PEG-containing carrier to a final concentration of 10 and 100 μmol/L. The morphological development of the embryo groups was evaluated according to the T. Fujimoto deve­lopment tables (2004), and the morphological parameters (diameter and area of roes, blastomers, embryos, embryo sac and blastodisk) were measured using ImageJ and Photoshop (CC 2014v15) programs. Results. Addition of the 10 μmol/L PEG-containing carrier to the medium initiated significant positive changes in the survival of loach embryos and prelarvae, in contrast to exposure to 100 μmol/L carrier. A significant increase in the area and diameter of blastomers and the embryos themselves under the influence of 100 μmol/L PEG carrier was established, which may indicate swelling of the embryos and a disruption of water-salt exchange that causes the early death of embryos. Conclusions. (1) Low embryotoxicity of the PEG-polymer was confirmed on the studied model of the loach embryos. Based on the obtained data and the original data of J. Maes et al. (2) PEG is an attractive polymeric carrier for the delivery of a variety of compounds to both embryos and prelarvae as well as other model subjects. Despite the fact that we investigated only two concentrations of the PEG-containing carrier, it is quite likely that these concentrations of the carrier are (3) biologically active in themselves and, therefore, a thorough selection of the PEG-carrier concentration for each objective of the model is needed.