Biology subjects

Krueger, T.

Publications and source records attributed to Krueger, T..

3 recordsLinked to original sources

bioRxiv2018

Tissue- and cellular-level allocation of autotrophic and heterotrophic nutrients in the coral symbiosis -- A NanoSIMS study

Corals access inorganic seawater nutrients through their autotrophic endosymbiotic dinoflagellates, but also capture planktonic prey through heterotrophic feeding. Correlating NanoSIMS and TEM imaging, we visualize and quantify the subcellular fate of autotrophic and heterotrophic C and N in the coral Stylophora pistillata using stable isotopes. Six scenarios were compared after 6h: autotrophic pulse (13C-bicarbonate, 15N-nitrate) in either unfed or regularly fed corals, and heterotrophic pulse (13C-, 15N-labelled brine shrimps) in regularly fed corals; each at ambient and elevated temperature. Host assimilation of photosynthates was similar under fed and unfed conditions, but symbionts assimilated 10% more C in fed corals. Photoautotrophic C was primarily channelled into host lipid bodies, whereas heterotrophic C and N were generally co-allocated to the tissue. Food-derived label was detected in some subcellular structures associated with the remobilisation of host lipid stores. While heterotrophic input generally exceeded autotrophic input, it was more negatively affected by elevated temperature. The reduced input from both feeding modes at elevated temperature was accompanied by a shift in the partitioning of C and N, benefiting epidermis and symbiont. This study provides a unique view on the nutrient partitioning in corals and highlights the tight connection of nutrient fluxes in symbiotic partners.

physiology↗

bioRxiv2018

A stochastic model of metastatic bottleneck predicts patient outcome and therapy response

Metastases are responsible for 90% of cancer-related deaths. Initiation of metastases, where newly seeded tumor cells expand into colonies, presents a tremendous bottleneck to metastasis formation. Despite its clinical importance, our understanding of this process is very limited. Here, we propose a simple stochastic model assuming that the initiating metastatic cells proliferate faster when surrounded by more of their kind. The model quantifies the severity of metastatic bottleneck as the probability that the seeded colony survives. Based on this model, we derive how metastasis occurrence depends on primary tumor size and affects patient outcome. Our predictions agree with epidemiological data for thirteen cancer types. The model predicts that impact of treatment decisions depends both on the primary tumor size and on the severity of the metastatic bottleneck, and that medical interventions that tighten the bottleneck would be much more efficient than therapies that decrease overall tumor burden, such as chemotherapy.

cancer biology↗

bioRxiv2017

Ancient symbiosis confers desiccation resistance to stored grain pest beetles

Microbial symbionts of insects provide a range of ecological traits to their hosts that are beneficial in the context of biotic interactions. However, little is known about insect symbiont-mediated adaptation to the abiotic environment, e.g. temperature and humidity. Here we report on an ancient (~400 Mya) clade of intracellular, bacteriome-located Bacteroidetes symbionts that are associated withgrain and wood pest beetles of the phylogenetically distant families Silvanidae and Bostrichidae. In the saw-toothed grain beetle Oryzaephilus surinamensis, we demonstrate that the symbionts affect cuticle thickness, melanization and hydrocarbon profile, enhancing desiccation resistance and thereby strongly improving fitness under dry conditions. Together with earlier observations on symbiont contributions to cuticle biosynthesis in weevils, our findings indicate that convergent acquisitions of bacterial mutualists represented key adaptations enabling diverse pest beetle groups to survive and proliferate under the low ambient humidities that characterize dry grain storage facilities.

evolutionary biology↗