These nano-sized motors are highly programmable and can be designed for use in molecular computation, diagnostics, and transport. Despite their genius, DNA-nanoparticle motors don’t have the speed of their biological counterparts, the motor protein, which is where the issue lies. This is where researchers come in to analyze, optimize, and rebuild a faster artificial motor using single-particle tracking experiment and geometry-based kinetic simulation.

“Natural motor proteins play essential roles in biological processes, with a speed of 10-1000 nm/s. Until now, artificial molecular motors have struggled to approach these speeds, with most conventional designs achieving less than 1 nm/s,” said Takanori Harashima, researcher and first author of the study.

Researchers published their work in Nature Communications on January 16th, 2025, featuring a proposed solution to the most pressing issue of speed: switching the bottleneck.

The experiment and simulation revealed that binding of RNase H is the bottleneck in which the entire process is slowed. RNase H is an enzyme involved in genome maintenance, and breaks down RNA in RNA/DNA hybrids in the motor. The slower RNase H binding occurs, the longer the pauses in motion, which is what leads to a slower overall processing time. By increasing the concentration of RNase H, the speed was markedly improved, showing a decrease in pause lengths from 70 seconds to around 0.2 seconds.

However, increasing motor speed came at the cost of processivity (the number of steps before detachment) and run-length (the distance the motor travels before detachment). Researchers found that this trade-off between speed and processivity/run-length could be improved by a larger DNA/RNA hybridization rate, bringing the simulated performance closer to that of a motor protein.

The engineered motor, with redesigned DNA/RNA sequences and a 3.8-fold increase in hybridization rate, achieved a speed of 30 nm/s, 200 processivity, and a 3 μm run-length. These results demonstrate that the DNA-nanoparticle motor is now comparable to a motor protein in performance.

“Ultimately, we aim to develop artificial molecular motors that surpass natural motor proteins in performance,” said Harashima. These artificial motors can be very useful in molecular computations based on the motion of the motor, not to mention their merit in the diagnosis of infections or disease-related molecules with a high sensitivity.

The experiment and simulation done in this study provide an encouraging outlook for the future of DNA-nanoparticle and related artificial motors and their ability to measure up to motor proteins as well as their applications in nanotechnology.

Takanori Harashima, Akihiro Otomo, and Ryota Iino of the Institute for Molecular Science at National Institutes of Natural Sciences and the Graduate Institute for Advanced Studies at SOKENDAI contributed to this research.

This work was supported by JSPS KAKENHI, Grants-in-Aid for Transformative Research Areas (A) (Publicly Offered Research) “Materials Science of Meso-Hierarchy” (24H01732) and “Molecular Cybernetics” (23H04434), Grant-in-Aid for Scientific Research on Innovative Areas “Molecular Engine” (18H05424), Grant-in-Aid for Early-Career Scientists (23K13645), JST ACT-X “Life and Information” (MJAX24LE), and Tsugawa foundation Research Grant for FY2023.

Scientists have discovered that juvenile bottlenose dolphins have specialized receptors for detecting the fatty acids in their mother’s milk. These findings, published in the journal Marine Mammal Science, offer important insights into how these marine mammals grow, feed, and communicate.

The new findings challenge previous assumptions about cetacean sensory systems. Unlike land mammals, dolphins and other marine mammals have limited olfactory capabilities – their sense of smell is largely nonfunctional in aquatic environments. Researchers have therefore speculated that dolphins had other ways of sensing their surroundings and detecting food.

Fat plays an essential role in providing energy and supporting brain development in dolphin calves, which are entirely dependent on their mother’s milk during their early stages of life.

“We looked at the tongue of a young Indo-Pacific bottlenose dolphin and confirmed special structures that may help it detect fat,” says the study’s first author Hinako Katsushima of the Graduate School of Environmental Science at Japan’s Hokkaido University. “At the back of the tongue, there’s a V-shaped row of taste receptors that are specifically tuned to pick up fatty acids. These receptors also have enzymes that help break down the fat, making it easier for the dolphin to sense and process it.”

In a second experiment, the team gave young dolphins a choice between two liquids: one containing milk and the other a cloudy solution. The dolphin showed an unexpected preference for the cloudy solution. This reinforces the finding that dolphins can distinguish between the two liquids, but the researchers are unsure why they avoided the milk. One possibility is that they found the milk unfamiliar – it was a mixture of milk from two females – and so avoided it from a fear of new foods, a habit called neophobia.

“Our findings suggest that the ability to detect fatty acids in their mother’s milk is part of a specialized ‘fat taste’ system that could help dolphins assess the nutritional value of their food,” says Assistant Professor Takashi Hayakawa from the Faculty of Environmental Earth Science at Hokkaido University, who led the study. “In the wild, where fat-rich diets are critical for survival, this capability may provide dolphins with an evolutionary advantage, allowing them to select high-quality milk from their mothers and later evaluate the nutritional content of their prey.”

The new study opens new avenues for understanding how marine mammals perceive and interact with their environment, as well as how they communicate and forage in the wild. Further research will be necessary to explore the full scope of this “fat taste” system and how it functions in other marine species.

Researchers have identified a key pathway that links how neurons send signals to each other, or synaptic activity, to the expression of genes necessary for long-term changes in the brain, providing crucial insights into the molecular processes underlying memory formation.

“These findings illuminate a critical mechanism that connects local synaptic activity to the broader gene expression changes necessary for learning and memory,” said Mark Dell’Acqua, professor of pharmacology at the University of Colorado Anschutz Medical Campus and senior author of the study. “This paper is mainly a basic science finding of a fundamental process of what nerve cells do. Understanding this relay system not only enhances our knowledge of brain function but could also better inform therapeutic treatments for cognitive disorders.”

The nucleus where the genes that modify neuron function are controlled is a long distance away from where neurons receive input from their synapses, which are located in distant dendrites that extend like branches from the trunk of a tree. This research focuses on the cAMP-response element binding protein (CREB), a transcription factor known to regulate genes vital for dynamic changes at synapses which is essential for neuronal communication. Despite CREB’s well-documented role in supporting learning and memory, the exact mechanisms leading to CREB activation during neuronal activity remain unclear.

Using advanced microscopy techniques, graduate student Katlin Zent in Dr. Dell’Acqua’s research group revealed a crucial relay mechanism involving the activation of receptors and ion channels generating calcium signals that rapidly communicates from synapses in remote dendrite branches to the nucleus in the neuron cell body.

“Going forward, this research will enable us to better examine the way these pathways are utilized in different disease states,” said Dell’Acqua. “We could see exactly what parts of this new mechanism are interfered with and where, giving us a better idea of how this pathway affecting learning and memory is impacted. This research highlights potential targets for interventions aimed at conditions like Alzheimer’s disease and other memory-related disorders.”