Analysis of the swimming-to-crawling transition of Caenorhabditis elegans in viscous fluid

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 2008.Includes bibliographical references (leaves 26-27).The locomotory behavior of the nematode Caenorhabditis elegans is often characterized by two distinct gaits - swimming when in fluids and crawling when on surfaces. Swimming is characterized by about a twice greater wavelength and about four time greater frequency of undulatory waves, compared with the crawling gait. These mechanisms which generate these gaits are not well-understood but have been suggested to be controlled by two separate neural circuits of central pattern generators. Here we studied the locomotion of young adult C. elegans in viscous fluids ranging from 0.001-1000 Pa s to determine whether there is a sharp or continuous transition between swimming and crawling. We characterized the locomotion by two parameters: the wavelength and the frequency of the undulating gaits. Our results for both parameters show a smooth transition, which suggests that there is only one neural circuit controlling forward locomotion which is modulated by the mechanical loading of the environment.by Risa Kawai.S.B

A Fully Automated High-Throughput Training System for Rodents

Addressing the neural mechanisms underlying complex learned behaviors requires training animals in well-controlled tasks, an often time-consuming and labor-intensive process that can severely limit the feasibility of such studies. To overcome this constraint, we developed a fully computer-controlled general purpose system for high-throughput training of rodents. By standardizing and automating the implementation of predefined training protocols within the animal’s home-cage our system dramatically reduces the efforts involved in animal training while also removing human errors and biases from the process. We deployed this system to train rats in a variety of sensorimotor tasks, achieving learning rates comparable to existing, but more laborious, methods. By incrementally and systematically increasing the difficulty of the task over weeks of training, rats were able to master motor tasks that, in complexity and structure, resemble ones used in primate studies of motor sequence learning. By enabling fully automated training of rodents in a home-cage setting this low-cost and modular system increases the utility of rodents for studying the neural underpinnings of a variety of complex behaviors

Required Elements in tRNA for Methylation by the Eukaryotic tRNA (Guanine-N2-) Methyltransferase (Trm11-Trm112 Complex)

The Saccharomyces cerevisiae Trm11 and Trm112 complex (Trm11-Trm112) methylates the 2-amino group of guanosine at position 10 in tRNA and forms N2-methylguanosine. To determine the elements required in tRNA for methylation by Trm11-Trm112, we prepared 60 tRNA transcript variants and tested them for methylation by Trm11-Trm112. The results show that the precursor tRNA is not a substrate for Trm11-Trm112. Furthermore, the CCA terminus is essential for methylation by Trm11-Trm112, and Trm11-Trm112 also only methylates tRNAs with a regular-size variable region. In addition, the G10-C25 base pair is required for methylation by Trm11-Trm112. The data also demonstrated that Trm11-Trm112 recognizes the anticodon-loop and that U38 in tRNAAla acts negatively in terms of methylation. Likewise, the U32-A38 base pair in tRNACys negatively affects methylation. The only exception in our in vitro study was tRNAValAAC1. Our experiments showed that the tRNAValAAC1 transcript was slowly methylated by Trm11-Trm112. However, position 10 in this tRNA was reported to be unmodified G. We purified tRNAValAAC1 from wild-type and trm11 gene deletion strains and confirmed that a portion of tRNAValAAC1 is methylated by Trm11-Trm112 in S. cerevisiae. Thus, our study explains the m2G10 modification pattern of all S. cerevisiae class I tRNAs and elucidates the Trm11-Trm112 binding sites

Azuki Bean Juice Lowers Serum Triglyceride Concentrations in Healthy Young Women

Effects of azuki bean juice supplementation, prescribed according to a Kanpo medicine regimen, on serum lipid concentrations were studied. Healthy young Japanese women were recruited and were randomly assigned to one of the three groups using a parallel-group design. Control (n = 10), azuki (n = 11) and Concentrated azuki (CA) (n = 12) juice groups consumed 150 g daily of the isocaloric assigned juice for one menstrual cycle with their usual diet. Triglyceride concentrations were decreased in the azuki juice group (p<0.05) and tended to be decreased in the CA juice group (p = 0.055). Triglyceride concentrations in the azuki and CA juice groups decreased by 0.170 mmol/liter (15.4%) and 0.159 mmol/liter (17.9%), respectively (p<0.05). The azuki and CA juice used in this study inhibited pancreatic lipase activity 29.2% and 56.9%, respectively, in vitro. Lipid peroxide changes, based on ANCOVA with the initial level and α-tocopherol changes as covariates, did not differ among the three groups. Serum low density lipoprotein-cholesterol and high density lipoprotein-cholesterol (HDL) cholesterol concentrations did not change. Thus, azuki bean juice intake, as a traditional Kampo prescription, might be beneficial for preventing hypertriglyceridemia

SARS-CoV-2 disrupts respiratory vascular barriers by suppressing Claudin-5 expression

臓器チップ技術を用いて新型コロナウイルスが血管へ侵入するメカニズムを解明 --Claudin-5発現抑制による呼吸器の血管内皮バリア破壊--. 京都大学プレスリリース. 2022-09-22.A study using an organ-on-a-chip reveals a mechanism of SARS-CoV-2 invasion into blood vessels --Disruption of vascular endothelial barrier in respiratory organs by decreasing Claudin-5 expression--. 京都大学プレスリリース. 2022-09-27.In the initial process of coronavirus disease 2019 (COVID-19), severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infects respiratory epithelial cells and then transfers to other organs the blood vessels. It is believed that SARS-CoV-2 can pass the vascular wall by altering the endothelial barrier using an unknown mechanism. In this study, we investigated the effect of SARS-CoV-2 on the endothelial barrier using an airway-on-a-chip that mimics respiratory organs and found that SARS-CoV-2 produced from infected epithelial cells disrupts the barrier by decreasing Claudin-5 (CLDN5), a tight junction protein, and disrupting vascular endothelial cadherin–mediated adherens junctions. Consistently, the gene and protein expression levels of CLDN5 in the lungs of a patient with COVID-19 were decreased. CLDN5 overexpression or Fluvastatin treatment rescued the SARS-CoV-2–induced respiratory endothelial barrier disruption. We concluded that the down-regulation of CLDN5 expression is a pivotal mechanism for SARS-CoV-2–induced endothelial barrier disruption in respiratory organs and that inducing CLDN5 expression is a therapeutic strategy against COVID-19

The role of motor cortex in the acquisition and production of learned motor sequences

Motor skill learning underlies much of what we do, be it hitting a tennis serve, playing the piano, or simply brushing our teeth. Yet despite its importance, little is known about the neural circuits that implement the learning process or how the motor program is represented in the brain. Here I explore the role of motor cortex through lesion studies in rats trained on a motor skill. First, I interrogate whether motor cortex is necessary for the production of a complex motor sequence by training animals to produce temporally precise self-initiated movement sequences on a lever-pressing task. The movement sequences that emerged over months of training were remarkably complex, yet very precise. This motor skill, once mastered, survives large bilateral motor cortex lesions, suggesting that motor cortex is not required for generating movement sequences after consolidation. Next, I explored the role of motor cortex in motor skills that require dexterous manipulations. Animals trained to make constrained spatially precise movements using a joystick were impaired after motor cortex lesions. The role of motor cortex thus depends on the nature of the movements involved but not on the sequencing of movements. Third, I explored the function of motor cortex in sensorimotor transformations by training animals on the same lever-pressing task but with external cues instead of self-initiated movement. Surprisingly, these animals were also not impaired after lesions, suggesting that the method of learning the motor sequence has no consequence once the motor sequences are consolidated. Lastly, I explored the role of motor cortex in learning motor skills. Animals that were lesioned after being exposed to the lever-pressing task could learn to adjust the timing of their movements, indicating that motor cortex is not required for adapting a previously-acquired motor sequence. Lesions of motor cortex prior to any training, however, severely disrupted learning. Even with extended training, animals were unable to fully master the task, demonstrating that motor cortex is necessary for the acquisition of new motor skills even when it is not required for their execution

Automated training of memory guided action sequences.

<p><b>A</b>. Structure of the behavioral task. An experimental block starts with a visually guided trial (left), in which the center LED indicates trial initiation. Upon moving the joystick down, the left (right) LED comes on. After a successful left (right) movement the LED turns off and the joystick is moved back to the center. A second movement is then cued by the right (left) LED. Upon moving the joystick right (left) a water reward is delivered. Any erroneous movement results in a timeout. After two consecutive correct trials, directional cues are not given and the movement sequence has to be performed from memory (right). After two consecutive correct memory guided trials (or ten total trials – an incomplete block), the next block commences with a new sequence. <b>B</b>. A sample run of 7 consecutive blocks from one animal. Each row represents one trial, with the sequence of movements color coded as in ‘A’. Left column denotes the target sequence (L-left movement; R-right movement). Shaded trials denote memory guided trials. Blocks denoted with asterisk correspond to perfect performance. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0083171#pone.0083171.s002" target="_blank">Video S2</a> shows experimental blocks 5-7. <b>C</b>-<b>D</b>. Aggregate performance of 4 rats trained in the task as measured by the fraction of completed blocks (<b>C</b>) and the number of memory guided trials until completion (<b>D</b>). Performance is compared to simulated chance (error-bars denote 95% confidence level). Data from 679 blocks for Rat 1, 647 blocks for Rat 2, 472 blocks for Rat 3 and 392 blocks for Rat 4.</p