Stabilization of microtubules by encapsulation of the GFP using a Tau-derived peptide

We constructed GFP-encapsulated microtubules (MTs) using Tauderived peptide which binds to their interior. The encapsulation of GFP dramatically increased the rigidity of MTs, resulting in their enhanced velocity on a kinesin-coated substrate. Moreover, the GFP-encapsulated MTs were significantly more stable compared to normal MTs

Cyclic Tau-derived peptides for stabilization of microtubules

The cyclization of peptides is a valuable strategy for the development of binding motifs to target proteins with improved affinity. Microtubules (MTs) are important targets for therapeutics, and a variety of MT-targeted drugs and peptides have recently been developed. We have previously designed a Tau-derived peptide (TP) that binds to the interior of MTs. In the present study, the development of a cyclic TP (TCP) for enhanced binding to tubulin and the stabilization of MTs is described. The fluorescently labeled cyclic peptide containing three glycine linkers (TCP3-TMR) exhibited a remarkably enhanced binding affinity to tubulin. The cyclic peptide was also demonstrated to stabilize MTs by enhancing polymerization and reducing depolymerization. Moreover, MTs were effectively formed by the treatment of cyclic peptides in the presence of guanosine triphosphate (GTP), while the linear peptide showed no such effect. These findings indicate that TCP is a useful binding motif that can stabilize MTs and is valuable for various therapeutic and material applications

Radial alignment of microtubules through tubulin polymerization in an evaporating droplet

© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Keya, J. J., Kudoh, H., Kabir, A. M. R., Inoue, D., Miyamoto, N., Tani, T., Kakugo, A., & Shikinaka, K. Radial alignment of microtubules through tubulin polymerization in an evaporating droplet. Plos One, 15(4), (2020): e0231352, doi:10.1371/journal.pone.0231352.We report the formation of spherulites from droplets of highly concentrated tubulin solution via nucleation and subsequent polymerization to microtubules (MTs) under water evaporation by heating. Radial alignment of MTs in the spherulites was confirmed by the optical properties of the spherulites observed using polarized optical microscopy and fluorescence microscopy. Temperature and concentration of tubulins were found as important parameters to control the spherulite pattern formation of MTs where evaporation plays a significant role. The alignment of MTs was regulated reversibly by temperature induced polymerization and depolymerization of tubulins. The formation of the MTs patterns was also confirmed at the molecular level from the small angle X-ray measurements. This work provides a simple method for obtaining radially aligned arrays of MTs.Fund receiver: Akira Kakugo Grant-in-Aid for Scientific Research on Innovative Areas (Grant Nos. JP24104004 and 18H05423) and a Grant-in-Aid for Scientific Research (A) (Grant No. 18H03673) from kaken. NO - The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscrip

Use of a single intramuscular injection of a synthetic hormone analogue,ovupin for commercial carp seed production in Bangladesh

A study was conducted to investigate the possibility of employing a single intramuscular injection of a synthetic hormone analogue, ovupin on the induced breeding of two major carps, viz. rohu (Labeo rohita), mrigala (Cirrhinus mrigala) and an endangered minor carp, bata (Labeo bata). Three breeding trials of each species were performed. In case of major carp, the females were injected with single dose of ovupin solution at a rate of 0.5 mL kg-1 body weight, while the minor carp received ovupin solution at a dose of 0.3 mL kg-1 body weight, whereas males received extracted PG hormone at a dose of 2 and 1.5 mg kg-1 body weight for major carps and minor carp, respectively. All the three species were successfully bred using ovupin through a single injection. In case of major carps, the latent period was 9-10 h while 12-14 h for minor carp. The breeding response of females was 100% in major carps, whereas it was approximately 90% in minor carp. Fertilization rate varied between 87.07 and 89.94% for the major carps and between 87.6 and 89.9% for minor carps. Major carps showed higher hatching rates (77.21 to 80.19%) than minor carp (64.9 to 66.56%). The present study indicated that ovupin could be effective as alternative of PG in carp’s breeding in Bangladesh

Complete, rapid and reversible regulation of the motility of a nano-biomolecular machine using an osmolyte trimethylamine-N-oxide

Nanoscale transportation in engineered environments is critical towards designing efficient and smart hybrid bio-nanodevices. Biomolecular motors, the smallest natural machines, are promising as actuators as well as sensors in hybrid nanodevices and hold enormous potentials in nanoscale transportation. Highly specific regulation of the activity of biomolecular motors is the key to control such integrated nanodevices. We present a simple method to regulate the activity of a biomolecular motor system, microtubule (MT)-kinesin by using a natural osmolyte trimethylamine-N-oxide (TMAO). Motility of kinesin-driven MTs in an in vitro gliding assay is regulated over a broad spectrum by using TMAO in a concentration dependent manner. The regulation of MT motility is rapid, reversible and repeatable over multiple cycles. Interestingly, the motility of MTs can be completely turned off using TMAO of a relatively high concentration. The halted motility of MTs is fully restored upon elimination of TMAO. Repeated cycles of TMAO addition and removal enable cyclical inhibition and restoration of the motility of MTs. These results demonstrate an ability to control nanoscale motion of a biomolecular motor in an artificial environment. This work facilitates further tunability over functions of biomolecular motors, which in turn will foster their nanotechnological applications, such as in nano-transportation

Molecular swarm robots : recent progress and future challenges

Recent advancements in molecular robotics have been greatly contributed by the progress in various fields of science and technology, particularly in supramolecular chemistry, bio- and nanotechnology, and informatics. Yet one of the biggest challenges in molecular robotics has been controlling a large number of robots at a time and employing the robots for any specific task as flocks in order to harness emergent functions. Swarming of molecular robots has emerged as a new paradigm with potentials to overcome this hurdle in molecular robotics. In this review article, we comprehensively discuss the latest developments in swarm molecular robotics, particularly emphasizing the effective utilization of bio- and nanotechnology in swarming of molecular robots. Importance of tuning the mutual interaction among the molecular robots in regulation of their swarming is introduced. Successful utilization of DNA, photoresponsive molecules, and natural molecular machines in swarming of molecular robots to provide them with processing, sensing, and actuating ability is highlighted. The potentials of molecular swarm robots for practical applications by means of their ability to participate in logical operations and molecular computations are also discussed. Prospects of the molecular swarm robots in utilizing the emergent functions through swarming are also emphasized together with their future perspectives

Effect of microtubule immobilization by glutaraldehyde on kinesin-driven cargo transport

The glutaraldehyde fixation method for fixing tissues is attractive for its ease of use and straightforward surface chemistry. We investigated the effect of glutaraldehyde-induced microtubule immobilization on kinesin-driven cargo transport along microtubules and found that at low glutaraldehyde concentrations, the microtubule-kinesin interaction remains unperturbed. Such findings may facilitate the application of the glutaraldehyde fixation method for many in vitro studies aiming to build nanodevices powered by the microtubule-motor protein interaction

Controlling the kinetics of interaction between microtubules and kinesins over a wide temperature range using the deep-sea osmolyte trimethylamine N-oxide

Trimethylamine N-oxide is found to be effective in regulating the interaction between microtubules and kinesins over a wide temperature range. The lifetime of the motility of microtubules on kinesins at high temperatures is prolonged using trimethylamine N-oxide. The activation energy of microtubule motility is increased by trimethylamine N-oxide. Prolonged operation at high temperatures decreased the activation energy of MT motility despite the increase in concentration of trimethylamine N-oxide

Fluctuation in the Sliding Movement of Kinesin-Driven Microtubules Is Regulated Using the Deep-Sea Osmolyte Trimethylamine N-Oxide

Nowadays, biomolecular motor-based miniaturized lab-on-a-chip devices have been attracting much attention for their wide range of nanotechnological applications. Most of the applications are dependent on the motor-driven active transportation of their associated filamentous proteins as shuttles. Fluctuation in the movement of the shuttles is a major contributor to the dispersion in motor-driven active transportation, which limits the efficiency of the miniaturized devices. In this work, by employing the biomolecular motor kinesin and its associated protein filament microtubule as a model active transport system, we demonstrate that the deep-sea osmolyte trimethylamine N-oxide (TMAO) is useful in regulating the fluctuation in the motility of microtubule shuttles. We show that the motional diffusion coefficient, a measure of the fluctuation in the movement of the kinesin-propelled microtubules, gradually decreases upon increasing the concentration of TMAO in the transportation system. We have been able to reduce the motional diffusion coefficient of microtubules more than 200 times by employing TMAO at a concentration of 2 M. We also show that upon elimination of TMAO, the motional diffusion coefficient of microtubules can be restored, which confirms that TMAO can be used as a tool to reversibly regulate the fluctuation in the sliding movement of kinesin-propelled microtubule shuttles. Such reversible regulation of the dynamic behavior of the shuttles does not require sacrificing the concentration of fuel used for transportation. Our results confirm the ability to manipulate the nanoscale motion of biomolecular motor-driven active transporters in an artificial environment. This work is expected to further enhance the tunability of biomolecular motor functions, which, in turn, will foster their nanotechnological applications based on active transportation