TY - JOUR A1 - Gómez-Nava, Luis A1 - Grossmann, Robert A1 - Hintsche, Marius A1 - Beta, Carsten A1 - Peruani, Fernando T1 - A novel approach to chemotaxis BT - active particles guided by internal clocks JF - epl : a letters journal exploring the frontiers of physics N2 - Motivated by the observation of non-exponential run-time distributions of bacterial swimmers, we propose a minimal phenomenological model for taxis of active particles whose motion is controlled by an internal clock. The ticking of the clock depends on an external concentration field, e.g., a chemical substance. We demonstrate that these particles can detect concentration gradients and respond to them by moving up- or down-gradient depending on the clock design, albeit measurements of these fields are purely local in space and instantaneous in time. Altogether, our results open a new route in the study of directional navigation: we show that the use of a clock to control motility actions represents a generic and versatile toolbox to engineer behavioral responses to external cues, such as light, chemical, or temperature gradients. Y1 - 2020 U6 - https://doi.org/10.1209/0295-5075/130/68002 SN - 0295-5075 SN - 1286-4854 VL - 130 IS - 6 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Alirezaeizanjani, Zahra A1 - Großmann, Robert A1 - Pfeifer, Veronika A1 - Hintsche, Marius A1 - Beta, Carsten T1 - Chemotaxis strategies of bacteria with multiple run modes JF - Science advances N2 - Bacterial chemotaxis-a fundamental example of directional navigation in the living world-is key to many biological processes, including the spreading of bacterial infections. Many bacterial species were recently reported to exhibit several distinct swimming modes-the flagella may, for example, push the cell body or wrap around it. How do the different run modes shape the chemotaxis strategy of a multimode swimmer? Here, we investigate chemotactic motion of the soil bacterium Pseudomonas putida as a model organism. By simultaneously tracking the position of the cell body and the configuration of its flagella, we demonstrate that individual run modes show different chemotactic responses in nutrition gradients and, thus, constitute distinct behavioral states. On the basis of an active particle model, we demonstrate that switching between multiple run states that differ in their speed and responsiveness provides the basis for robust and efficient chemotaxis in complex natural habitats. KW - exploit KW - flagellum KW - instability KW - time Y1 - 2020 U6 - https://doi.org/10.1126/sciadv.aaz6153 SN - 2375-2548 VL - 6 IS - 22 PB - American Association for the Advancement of Science CY - Washington ER - TY - JOUR A1 - Hintsche, Marius A1 - Waljor, Veronika A1 - Grossmann, Robert A1 - Kühn, Marco J. A1 - Thormann, Kai M. A1 - Peruani, Fernando A1 - Beta, Carsten T1 - A polar bundle of flagella can drive bacterial swimming by pushing, pulling, or coiling around the cell body JF - Scientific reports N2 - Bacteria swim in sequences of straight runs that are interrupted by turning events. They drive their swimming locomotion with the help of rotating helical flagella. Depending on the number of flagella and their arrangement across the cell body, different run-and-turn patterns can be observed. Here, we present fluorescence microscopy recordings showing that cells of the soil bacterium Pseudomonas putida that are decorated with a polar tuft of helical flagella, can alternate between two distinct swimming patterns. On the one hand, they can undergo a classical push-pull-push cycle that is well known from monopolarly flagellated bacteria but has not been reported for species with a polar bundle of multiple flagella. Alternatively, upon leaving the pulling mode, they can enter a third slow swimming phase, where they propel themselves with their helical bundle wrapped around the cell body. A theoretical estimate based on a random-walk model shows that the spreading of a population of swimmers is strongly enhanced when cycling through a sequence of pushing, pulling, and wrapped flagellar configurations as compared to the simple push-pull-push pattern. Y1 - 2017 U6 - https://doi.org/10.1038/s41598-017-16428-9 SN - 2045-2322 VL - 7 PB - Macmillan Publishers Limited, part of Springer Nature CY - London ER - TY - JOUR A1 - Stange, Maike A1 - Hintsche, Marius A1 - Sachse, Kirsten A1 - Gerhardt, Matthias A1 - Valleriani, Angelo A1 - Beta, Carsten T1 - Analyzing the spatial positioning of nuclei in polynuclear giant cells JF - Journal of Physics D: Applied Physics N2 - How cells establish and maintain a well-defined size is a fundamental question of cell biology. Here we investigated to what extent the microtubule cytoskeleton can set a predefined cell size, independent of an enclosing cell membrane. We used electropulse-induced cell fusion to form giant multinuclear cells of the social amoeba Dictyostelium discoideum. Based on dual-color confocal imaging of cells that expressed fluorescent markers for the cell nucleus and the microtubules, we determined the subcellular distributions of nuclei and centrosomes in the giant cells. Our two- and three-dimensional imaging results showed that the positions of nuclei in giant cells do not fall onto a regular lattice. However, a comparison with model predictions for random positioning showed that the subcellular arrangement of nuclei maintains a low but still detectable degree of ordering. This can be explained by the steric requirements of the microtubule cytoskeleton, as confirmed by the effect of a microtubule degrading drug. KW - Dictyostelium KW - cell nucleus KW - positioning KW - imaging KW - spatial poisson distribution Y1 - 2017 U6 - https://doi.org/10.1088/1361-6463/aa8da0 SN - 0022-3727 SN - 1361-6463 VL - 50 IS - 46 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Raatz, Michael A1 - Hintsche, Marius A1 - Bahrs, Marco A1 - Theves, Matthias A1 - Beta, Carsten T1 - Swimming patterns of a polarly flagellated bacterium in environments of increasing complexity JF - European physical journal special topics N2 - The natural habitat of many bacterial swimmers is dominated by interfaces and narrow interstitial spacings where they frequently interact with the fluid boundaries in their vicinity. To quantify these interactions, we investigated the swimming behavior of the soil bacterium Pseudomonas putida in a variety of confined environments. Using microfluidic techniques, we fabricated structured microchannels with different configurations of cylindrical obstacles. In these environments, we analyzed the swimming trajectories for different obstacle densities and arrangements. Although the overall swimming pattern remained similar to movement in the bulk fluid, we observed a change in the turning angle distribution that could be attributed to collisions with the cylindrical obstacles. Furthermore, a comparison of the mean run length of the bacteria to the mean free path of a billiard particle in the same geometry indicated that, inside a densely packed environment, the trajectories of the bacterial swimmers are efficiently guided along the open spacings. Y1 - 2015 U6 - https://doi.org/10.1140/epjst/e2015-02454-3 SN - 1951-6355 SN - 1951-6401 VL - 224 IS - 7 SP - 1185 EP - 1198 PB - Springer CY - Heidelberg ER -