Development of senescence biomarkers in the common woodlouse

Over time, damages accumulate in the cells leading to the process of cell senescence. Many cellular modifications can then attest to this process and are called senescence biomarkers. Senescence biomarkers are highly studied in humans and are particularly useful for understanding the processes involved in age-related diseases. However, while studies on ageing are increasingly focusing on invertebrate models, senescence biomarkers remain poorly developed in these organisms. In this study, we looked at the effect of age on three known biomarkers in vertebrates: immune cells (cell size, density and viability), beta-galactosidase activity and telomerase expression on A. vulgare, a terrestrial isopod. As expected, the size of immune cells was higher in older individuals while their density and viability decreased, β-galactosidase activity increased with age while Telomerase Reverse Transcriptase (TERT) gene expression decreased. These biomarkers classically used in vertebrates are thus correlated with age in our invertebrate model and make good biomarkers to highlight cell senescence in A. vulgare. A strong gender effect was also observed on markers and could indicate different resource allocation strategies. This last point encourages us to use the biomarkers developed here to understand the other factors involved in the diversity of senescence patterns observed in living world.