Evaluation of cockerel spermatozoa viability and motility by a novel enzyme based cell viability assay

Response of earthworm coelomocytes and catalase to pentanone and hexanone: a revelation of the toxicity of conventional solvents at the cellular and molecular level

Organic solvents like 2-pentanone and 2-hexanone which are widely used in industrial production make up a large proportion of the source of chemical pollution. What is worrisome is that the cellular and molecular toxicity of 2-pentanone and 2-hexanone has not been reported yet. Based on this, earthworms and catalase (CAT) were chosen as target receptors for the toxicity studies. The cytotoxicity of 2-pentanone and 2-hexanone was revealed by measuring the multiple intracellular indicators of oxidative stress. At the molecular level, changes in the structure and function of CAT were characterized in vitro by the spectroscopy and molecular docking. The results show that 2-pentanone and 2-hexanone that induced the accumulation of reactive oxygen species can eventually reduce coelomocytes viability, accompanying by the regular changes of antioxidant activity and lipid peroxidation level. In addition, the exposure of 2-pentanone and 2-hexanone can shrink the backbone structure of CAT, quench the fluorescence, and misfold the secondary structure. The decrease in enzyme activity should be attributed to the structural changes induced by surface binding. This study discussed the toxicological effects and mechanisms of conventional solvents at the cellular and molecular level, which creatively proposed a joint research method.

The MTT assay application to measure the viability of spermatozoa: A variety of the assay protocols

The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction assay is one of the methods used to evaluate the viability of sperm. In the assay, a tetrazolium component (MTT) is converted into MTT formazan by some specific enzymes in the viable cells. The amount of formazan product in theory is directly correlated with the percentage of viable sperms. It is quantified by measuring the absorbance using a spectrophotometer. The present article compiles the MTT assays that have been used to determine sperm viability in most animal species and humans. In each assay, other factors apart from the number of viable cells that potentially influence the accuracy and precision of results are stated, such as preparations of sperm and MTT solutions, length and conditions of incubation, and a solubilizing agent as well as the formazan detection method. Also, the strengths and shortcomings of the MTT test comparison with the others are summarized at the end of this article. This information may be useful for prospective researchers deciding to implement this colorimetric method in their experiments.

Tetrazolium Salt WST-8 as a Novel and Reliable Chromogenic Indicator for the Assessment of Boar Semen Quality

Simple Summary

Good semen quality is an essential factor for breeding success when artificial insemination is performed. However, semen quality can not fully be evaluated by merely sperm viability or motility. Standard semen quality evaluation requires costly automated computer-assisted sperm analysis or specific and laborious labeling procedures before particular parameters can be assessed by flow cytometry. In the current study, we examined whether the 2-[2-methoxy-4-nitrophenyl]-3-[4-nitrophenyl]-5-[2,4-disulfophenyl]-2H-tetrazolium (WST-8) assay, which is widely used in the cell biology field, can be applied to evaluate sperm viability, and moreover, whether the WST-8 reduction rate can correlate with multiple sperm parameters that are related to sperm quality. We demonstrated in this study that the WST-8 assay can be used as a rapid, affordable, and reliable method for the prediction of semen quality in boar.

Abstract

A tetrazolium salt, 2-[2-methoxy-4-nitrophenyl]-3-[4-nitrophenyl]-5-[2,4-disulfophenyl]-2H-tetrazolium (WST-8), has been used widely to determine cell viability; however, its application in the field of reproduction is still limited due to this assay merely providing information regarding cell viability. The aim of this study was to correlate the WST-8 reduction rate with various sperm quality-related parameters (i.e., sperm viability, motility, progressive motility, acrosome integrity and mitochondria integrity) in order to provide a rapid, reliable and affordable assessment for boar semen quality evaluation. Using different ratios of active/damaged sperm cells, we first validated our sample preparations by standard flow cytometry and computer-assisted sperm analysis. Further analyses demonstrated that the most efficient experimental condition for obtaining a reliable prediction model was when sperm concentration reached 300 × 10⁶ cells/mL with the semen/cell-counting kit-8 (CCK-8^®) ratio of 200/10 and incubated time of 20 min. Under this set up, the WST-8 reduction rate (differences on optic density reading value, ΔOD at 450 nm) and sperm parameters were highly correlated (p < 0.01) for all sperm parameters evaluated. In the case of limited semen samples, a minimal semen concentration at 150 × 10⁶ cells/mL with the semen/CCK-8^® ratio of 200/20 and incubation time for 30 min could still provide reliable prediction of sperm parameters using the WST-8 assay. Our data provide strong evidence for the first time that the WST-8 assay could be used to evaluate boar semen quality with great potential to be applied to different mammalian species.