Biology subjects

Gerber, N.

Publications and source records attributed to Gerber, N..

3 recordsLinked to original sources

bioRxiv2025

Acoustofluidic patterning for improved microtissue histology

Microtissues (such as organoids or spheroids) are useful to model healthy or diseased human tissues and organs, with application in drug testing, tissue engineering, and personalized medicine. To characterize their morphology and phenotype, microtissues are often monitored using histology and high-resolution imaging. While this technique is well-established and standard for macroscopic tissue sections, it remains challenging to execute and has low throughput in the context of these sub-millimeter structures, mainly due to the fact that their size makes them difficult to locate within the embedding medium. To enhance the efficiency of microtissue histology, we developed an acoustofluidic device that arranges microtissues in a coplanar arrangement within HistoGel, a widely used embedding medium. Pre-patterning microtissues within HistoGel streamlines downstream processing by positioning the centers of mass of the microtissues at a pre-defined plan in the sample, simplifying sectioning, labeling, and imaging. We validated the method using differently sized HepG2 microtissues and tumor microtissues from osteosarcoma cells (Saos-2, MG-63, HOS), demonstrating that this method can be applied to different microtissue shapes, sizes, and types, without modifying established post-processing techniques. Our approach substantially enhances the microtissue histology workflow and broadens possibilities for microtissue analysis.

bioengineering↗

bioRxiv2020

Population density and temperature influence the return on maternal investment in wild house mice

In mammals, reproduction is influenced by competitive stress, temperature and food availability and these factors might be crucial already during early life. Favourable early life environment and high maternal investment are expected to improve survival and reproduction. In mammals, maternal investment via lactation predicts offspring growth. As body mass is often associated with fitness consequences, females have the potential to influence offspring fitness through their level of investment, which might interact with effects of population density and temperature. Here, we investigate the relationship between pup body mass at day 13 (used as approximation for weaning mass) and individual reproductive parameters as well as longevity under natural variation in population density and temperatures. Further, we assess the extent to which mothers influence the body mass of their offspring until weaning. We analysed life data of 384 house mice (Mus musculus domesticus) from a free-living wild population that was not food limited. We found a complex effect of population density, temperature and maternal investment on life-history traits related to fitness: Shorter longevity with increasing pup body mass at day 13; delayed reproduction of heavier pups when raised at warmer temperatures; and increased lifetime reproductive success for heavier pups at high densities. House mice could use population density and temperature as cues for predicting future environmental conditions, allowing a mother to adjust her investment according to the environment in which offspring will breed in order to maximise fitness. This study highlights the importance of considering ecological conditions in combination with maternal effects.

evolutionary biology↗

bioRxiv2020

Sex ratio and sexual conflict in a collective action problem

The maintenance of cooperation is difficult whenever collective action problems are vulnerable to freeriding (reaping the benefits without contributing to the maintenance of the good). We identify a novel factor that can make a system tolerate an extent of freeriding. If a population consists of discrete types with demographically distinct roles, such that the success of one type does not imply it can spread to replace other types in the population, then collective goods may persist in the presence of free-riders because they are necessarily kept in a minority role. Biased sex ratios (e.g. in haplodiploids) create conditions where individuals of one sex are a minority. We show that this can make the less common sex contribute less to a public good in a setting where the relevant life-history stage -- larval group defence against predators -- does not feature any current breeding opportunities that might lead to confounding reasons behind sex-specific behaviour. We test our model with haplodiploid pine sawfly larvae, showing that female larvae are the main contributors to building the antipredator defence against predators. Significance statementIndividuals in groups can cooperate to achieve something together, but with an evolutionary difficulty: if benefits of cooperation are shared equally among all, freeriders get the same benefit as others while paying less for it. We propose a novel reason why freeriding does not automatically spread until the collectively beneficial outcome is destroyed: sometimes groups consist of individuals of distinct categories, limiting freerider spread. If, for example, there are always fewer males than females, then even if every male becomes a freerider, the whole group still survives simply because not everyone can be male. Pine sawfly larvae defend against predators by regurgitating sticky fluids, but females contribute more to this common defence, and we show this example fits our model.

evolutionary biology↗