been projected to exceed 20% by 2025, while in the US, the aged population is expected to double between 2010 and 2050 to reach 89 million. [2] However, the extension of lifespan has not necessarily been accompanied by a proportional increase in healthspan-the length of healthy lifeand the final 20% of human lifespan is commonly associated with some degree of morbidity. [1] As such, a focal point in aging research is the formulation of medical interventions that compress late-life morbidity. [1][2][3][4] One major challenge toward this aim is that the beneficial effects and efficacy of therapeutic treatments likely vary among individuals because of the heterogeneity of human aging. [2] For instance, human monozygotic twins show different lengths in lifespan, [5] discordance in the development of type I diabetes, [6] and even major variability in the size of organs. [7] Although the genetic and environmental influences on aging have been studied extensively, non-genetic and other stochastic factors affecting the aging process are much less well understood. As demonstrated in model organisms such as Caenorhabditis elegans, the aging process shows a high degree of variability among individuals sharing the same genetic and environmental background.In this study, we investigated population heterogeneity of the aging process using the model organism C. elegans. The nematode C. elegans is a small (≈1 mm in length) and fast Significant non-genetic stochastic factors affect aging, causing lifespan differences among individuals, even those sharing the same genetic and environmental background. In Caenorhabditis elegans, differences in heat-shock response (HSR) are predictive of lifespan. However, factors contributing to the heterogeneity of HSR are still not fully elucidated. Here, the authors characterized HSR dynamics in isogenic C. elegans expressing GFP reporter for hsp-16.2 for identifying the key contributors of HSR heterogeneity. Specifically, microfluidic devices that enable cross-sectional and longitudinal measurements of HSR dynamics in C. elegans at different scales are developed: in populations, within individuals, and in embryos. The authors adapted a mathematical model of HSR to single C. elegans and identified model parameters associated with proteostasis-maintenance of protein homeostasis-more specifically, protein turnover, as the major drivers of heterogeneity in HSR dynamics. It is verified that individuals with enhanced proteostasis fidelity in early adulthood live longer. The model-based comparative analysis of protein turnover in day-1 and day-2 adult C. elegans revealed a stochastic-onset of age-related proteostasis decline that increases the heterogeneity of HSR capacity. Finally, the analysis of C. elegans embryos showed higher HSR and proteostasis capacity than young adults and established transgenerational contribution to HSR heterogeneity that depends on maternal age.

Transformation, i.e. reprogramming of bacteria by delivering exogenous genetic material (such as DNA) into the cytoplasm, is a key process in molecular engineering and modern biotechnology in general. Transformation is often performed by electroporation, i.e. creating pores in the membrane using electric shocks in a low conductivity environment. However, cell preparation for electroporation can be cumbersome as it requires the exchange of growth medium (high-conductivity) for low-conductivity medium, typically performed via multiple time-intensive centrifugation steps. To simplify and miniaturize this step, we developed an acoustofluidic device capable of trapping the bacterium <i>Escherichia coli </i>non-invasively for subsequent exchange of medium, which is challenging in acoustofludic devices due to detrimental acoustic streaming effects. <br>With an improved etching process, we were able to produce a thin wall between two microfluidic channels, which, upon excitation, can generate streaming fields that complement the acoustic radiation force and therefore can be utilized for trapping of bacteria. Our novel design robustly traps <i>Escherichia coli</i> at a flow rate of 10 µL minute^-1 and has a cell recovery performance of 47 ± 3 % after washing the trapped cells.<br>To verify that the performance of the medium exchange device is sufficient, we tested the electrocompetence of the recovered cells in a standard transformation procedure and found a transformation efficiency of 8∙10⁵ CFU per µg of plasmid DNA. Our device is a viable low-volume alternative to centrifugation-based methods and opens the door for miniaturization of a plethora of microbiological and molecular engineering protocols.<br>

Genetics, environment, and stochasticity influence the rate of ageing in living organisms. Individual Caenorhabditis elegans that are genetically identical and cultured in the same environment have different lifespans, suggesting a significant role of stochasticity in ageing. We have developed a novel microfluidic methodology to measure heat-shock response as a surrogate marker for heterogeneity associated with lifespan and have quantified the heatshock response of C. elegans at the population, single individual, and tissue levels. We have further mathematically modelled our data to identify the major drivers determining such heterogeneity. This approach demonstrates that protein translation and degradation rate constants explain the individuality of the heat-shock time-course dynamic. We observed a decline of protein turnover capacity in early adulthood, co-incidentally occurring as the predicted proteostasis collapse. We identified a decline of intestinal response as the tissue that underlies the individual heterogeneity. Additionally, we verified that individuals with enhanced translation fidelity in early adulthood live longer. Altogether, our results reveal that the stochastic onset of proteostasis collapse of somatic tissues during early adulthood reflects individual protein translation capacity underlying heterogenic ageing of isogenic C. elegans.