#37 Nano-Robots, Bees of the Sea and Swimming Without Swimming...
DNA made Nano-robots, crustaceans are the bees of the sea and bacteria swimming without a brain or muscles...
Nano-robots built entirely from DNA…
A team of researchers and scientists from Inserm, SNRS and Université de Montpellier at the Structural Biology Center in Montpellier have been constructing a small robot made of DNA. The aim is for it to be used in studying cell processes otherwise invisible to the naked eye. The highly innovative “nano-robot” would enable a closer studying of the mechanical forces that are applied at microscopic levels.
Our cells are subject to biological signals that are essential to many cell processes involved in the normal functioning of our body or in disease development. The feeling of touch for example is given by mechanoreceptors. These specific cell receptors are sensitive to mechanical forces and enable the regulation of other key biological processes such as blood vessel constriction, pain perception, breathing and more…
Cancer and other diseases can cause the dysfunction of this cellular mechanosensitivity. Cancer cells migrate within the body constantly adapting to the mechanical properties of their microenvironment. This adaptation is mainly possible because specific forces are detected by mechanoreceptors that transmit the information to the cell cytoskeleton.
The current scientific communities knowledge of these molecular mechanisms involved in cell mechanosensitivity is still somewhat limited. Whilst a few technologies are already available to apply controlled forces and study these mechanisms, they have a number of limitations.
The nanorobot is made using a DNA origami method. This method enables the use of self assembly 3D nanostructures in a pre-defined form using the DNA molecule as construction material. Over the last 10 years the technique has allowed major advances in the field…
The robot, nanometric in size is compatible with the size of a human cell. This is the first time that a human made, self assembled DNA-based object can apply force with this accuracy. The team coupled the robot with a molecule that is recognised by a mechanoreceptor. This meant that it is possible to direct the robot to some of our cells and specifically apply forces to targeted mechanoreceptors localised on the surface of the cells in order to activate them. This could be a valuable tool for basic research, and could be used to better understand the molecular mechanisms involved in cell mechanosensitivity.
“The design of a robot enabling the in vitro and in vivo application of piconewton forces meets a growing demand in the scientific community and represents a major technological advance. However, the biocompatibility of the robot can be considered both an advantage for in vivo applications but may also represent a weakness with sensitivity to enzymes that can degrade DNA. So our next step will be to study how we can modify the surface of the robot so that it is less sensitive to the action of enzymes. We will also try to find other modes of activation of our robot using, for example, a magnetic field,” emphasizes Bellot, an Inserm researcher who led the team.
🐝Bees of the Sea
Idoteas are the bees of the sea…
Idotea is a genus of isopod crustaceans, mostly found in colder temperate waters. These small marine creatures play a role in the reproduction of red algae as they transport male gametes from one alga to another.
Algal fertilisation assisted by marine animals is relatively lesser known about in comparison to insects and the pollination of flowers. A team has discovered how the small crustaceans known as Idoteas, contribute to the reproductive cycle of the red alga.
Previously scientists believed that the dispersal of the male gametes/ spermatia of the red algae was solely through water movement, now scientists recognise the role that is played by animals. The idoteas contribute to the fertilisation of G. gracilis as they swim amid these algae. The surfaces of the male algae are dotted with reproductive structures that produce the spermatia which is coated in a sticky substance. As the small crustacean passes by, the spermatia adhere to its cuticles. The gametes are then deposited on the thalli of any female alga that the crustacean comes into contact with.
However this relationship is not a solely communalistic relationship. The idoteas benefit from the arrangement too. The idotea cling to the algae as a protection from strong currents, and they eat the small organisms growing on their thalli. This is a mutualistic interaction, a win win for both. This is the first example of an interaction of this kind between seaweed and an animal.
Whilst these findings do not indicate the extent of transportation and how important the crustaceans input is in relation to water movement, it does offer a surprising insight into the origin of animal mediated fertilization of plants. Before this discovery, the animal mediated fertilization of plants was assumed to have emerged among terrestrial plants 140 million years ago. Red algae arose over 800 million years ago and their fertilisation via animal intermediaries may long predate the origin of pollination on land.
🏊♀️Swimming without Swimming
Swimming without brains or muscles…
Whilst bacteria and other unicellular organisms are comparably simple structures, they have developed sophisticated ways of swimming. The research team from the Max Planck institute used oil droplets as a model for biological swimmers.
Biological organisms have to be able to adapt and react to their environment. Whilst animals have an ability to make conscious decisions to sense and react to their surroundings, unicellular organisms have developed different strategies. Small organisms such as parasites and bacteria navigate through narrow channels such as blood vessels. This is often done in a regular, oscillating manner, based on hydrodynamic interactions with the channels walls.
“In our experiments, we could confirm the theoretical model that describes the specific dynamics of the microswimmer based on its size and the interactions with the channel wall” said Corinna Maass, the principal investigator of the study.
Another study showed how the researchers investigated moving microswimmers mutually and how this affected each other. Small oil droplets in a soapy solution move autonomously by budding of little amounts of oil, which generates propulsion. The microswimmers generate a trace of used ‘fuel’ which can repel others. This allows the microswimmers to detect if another swimmer has been at the same place shortly before.
“Interestingly, this causes a self-avoiding movement for individual microswimmers, whereas an ensemble of them results in droplets being caged between the trails of one another” reports Babak Vajdi Hokmabad, first author of the study. The repelling of the second droplet at the trajectory of a previously passing one, depends on its approaching angle and the time passed after the first swimmer.
Finally, the group also investigated the collective hydrodynamic behaviour of multiple microswimmers. The team found that multiple droplets can form clusters that spontaneously start to float like hovercrafts or rise of rotate like microscopic helicopters. The rotation of this cluster is based on the cooperative coupling between the individual droplets which leads to coordinated behaviour although individual droplets alone do not comprise such movement. This demonstrates yet another physical principle of how microswimmers are able to navigate their way without muscles or brains.
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Mills, A., Aissaoui, N., Maurel, D., Elezgaray, J., Morvan, F., Vasseur, J., Margeat, E., Quast, R., Lai Kee-Him, J., Saint, N., Benistant, C., Nord, A., Pedaci, F. and Bellot, G., 2022. A modular spring-loaded actuator for mechanical activation of membrane proteins. Nature Communications, 13(1).
News Release Information - https://presse.inserm.fr/en/a-nano-robot-built-entirely-from-dna-to-explore-cell-processes/45568/
🐝Bees of the Sea
Lavaut, E., Guillemin, M., Colin, S., Faure, A., Coudret, J., Destombe, C. and Valero, M., 2022. Pollinators of the sea: A discovery of animal-mediated fertilization in seaweed. Science, 377(6605), pp.528-530.
News Press Release https://www.cnrs.fr/en/idoteas-are-seas-bees
🏊♀️Swimming without Swimming
Hokmabad, B., Agudo-Canalejo, J., Saha, S., Golestanian, R. and Maass, C., 2022. Chemotactic self-caging in active emulsions. Proceedings of the National Academy of Sciences, 119(24).
News press release: https://www.ds.mpg.de/3950372/220729_microswimmers