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Dive into the research topics where Jinzhou Yuan is active.

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Featured researches published by Jinzhou Yuan.


Sleep | 2013

Caenorhabditis-in-drop array for monitoring C. elegans quiescent behavior

Samuel Belfer; Han Sheng Chuang; Benjamin L. Freedman; Jinzhou Yuan; Michael M. Norton; Haim H. Bau; David M. Raizen

STUDY OBJECTIVES To develop a method, called Caenorhabditis-in-Drop (CiD), encapsulating single worms in aqueous drops, for parallel analysis of behavioral quiescence in C. elegans nematodes. DESIGN We designed, constructed, and tested a device that houses an array of aqueous droplets laden with individual worms. The droplets are separated and covered by immiscible, biocompatible oil. We modeled gas exchange across the aqueous/oil interface and tested the viability of the encapsulated animals. We studied the behavior of wild-type animals; of animals with a loss of function mutation in the cGMP-dependent protein kinase gene egl-4; of animals with a loss of function mutation in the gene kin-2, which encodes a cAMP-dependent protein kinase A regulatory subunit; of animals with a gain-of-function mutation in the gene acy-1, which encodes an adenylate cyclase; and of animals that express high levels of the EGF protein encoded by lin-3. MEASUREMENTS AND RESULTS We used CiD to simultaneously monitor the behavior of 24 worms, a nearly 5-fold improvement over the prior best methodology. In support of our gas exchange models, we found that worms remain viable on the chip for 4 days, past the 12-h period needed for observation, but show reduced longevity to that measured on an agar surface. Measurements of duration of lethargus quiescence and total leth-argus quiescence showed reduced amounts as well as reduced variability relative to prior methods. There was reduced lethargus quiescence in animals that were mutant for kin-2 and for acy-1, supporting a wake-promoting effect of PKA in C. elegans, but no change in lethargus quiescence in egl-4 mutants. There was increased quiescence in animals that expressed kin-2 in the nervous system or over-expressed EGF. CONCLUSIONS CiD is useful for the analysis of behavioral quiescence during lethargus as well as during the adult stage C. elegans. The method is expandable to parallel simultaneous monitoring of hundreds of animals and for other studies of long-term behavior. Using this method, we were successful in measuring, for the first time, quiescence in kin-2(ce179) and in acy-2(ce2) mutants, which are hyperactive. Our observations also highlight the impact of environmental conditions on quiescent behavior and show that longevity is reduced in CiD in comparison to agar surfaces.


Proceedings of the National Academy of Sciences of the United States of America | 2014

Gait synchronization in Caenorhabditis elegans

Jinzhou Yuan; David M. Raizen; Haim H. Bau

Significance How independent agents interact to form collective behavior is of interest in diverse disciplines. Larger animals coordinate their motions via their nervous systems. However, little is known regarding the mechanisms by which microscopic animals coordinate their gaits. We observed that, when in a swarm, clusters of Caenorhabditis elegans synchronize their swimming gait. To identify the mechanism responsible for this behavior, we devised controlled experiments to examine the interactions between pairs of animals. Our studies indicate that steric hindrance is the dominant factor responsible for gait synchronization in C. elegans, and that hydrodynamic interactions and mechanosensation do not play a significant role. We infer that a similar mechanism may apply to other microscopic swimming organisms and self-propelled particles. Collective motion is observed in swarms of swimmers of various sizes, ranging from self-propelled nanoparticles to fish. The mechanisms that govern interactions among individuals are debated, and vary from one species to another. Although the interactions among relatively large animals, such as fish, are controlled by their nervous systems, the interactions among microorganisms, which lack nervous systems, are controlled through physical and chemical pathways. Little is known, however, regarding the mechanism of collective movements in microscopic organisms with nervous systems. To attempt to remedy this, we studied collective swimming behavior in the nematode Caenorhabditis elegans, a microorganism with a compact nervous system. We evaluated the contributions of hydrodynamic forces, contact forces, and mechanosensory input to the interactions among individuals. We devised an experiment to examine pair interactions as a function of the distance between the animals and observed that gait synchronization occurred only when the animals were in close proximity, independent of genes required for mechanosensation. Our measurements and simulations indicate that steric hindrance is the dominant factor responsible for motion synchronization in C. elegans, and that hydrodynamic interactions and genotype do not play a significant role. We infer that a similar mechanism may apply to other microscopic swimming organisms and self-propelled particles.


Proceedings of the National Academy of Sciences of the United States of America | 2015

Propensity of undulatory swimmers, such as worms, to go against the flow.

Jinzhou Yuan; David M. Raizen; Haim H. Bau

Significance Undulating swimmers, such as worms, are ubiquitous and play important roles in the ecosystem; agriculture; human, animal, and plant health; and medical research. The ability of undulatory swimmers to align against the flow (rheotax) is important in the animals’ life cycles, enabling them to navigate their environment and to maintain their positions in the presence of adverse flows such as in the hosts’ guts and blood vessels. We elucidate, for the first time to our knowledge, the mechanism responsible for rheotaxis in low-Reynolds-number, undulatory swimmers. This knowledge will provide a better understanding of the animals’ life cycles, will enable the development of strategies to disturb their life cycles, and will improve the design of microfluidic devices for biological research. The ability to orient oneself in response to environmental cues is crucial to the survival and function of diverse organisms. One such orientation behavior is the alignment of aquatic organisms with (negative rheotaxis) or against (positive rheotaxis) fluid current. The questions of whether low-Reynolds-number, undulatory swimmers, such as worms, rheotax and whether rheotaxis is a deliberate or an involuntary response to mechanical forces have been the subject of conflicting reports. To address these questions, we use Caenorhabditis elegans as a model undulatory swimmer and examine, in experiment and theory, the orientation of C. elegans in the presence of flow. We find that when close to a stationary surface the animal aligns itself against the direction of the flow. We elucidate for the first time to our knowledge the mechanisms of rheotaxis in worms and show that rheotaxis can be explained solely by mechanical forces and does not require sensory input or deliberate action. The interaction between the flow field induced by the swimmer and a nearby surface causes the swimmer to tilt toward the surface and the velocity gradient associated with the flow rotates the animal to face upstream. Fluid mechanical computer simulations faithfully mimic the behavior observed in experiments, supporting the notion that rheotaxis behavior can be fully explained by hydrodynamics. Our study highlights the important role of hydrodynamics in the behavior of small undulating swimmers and may assist in developing control strategies to affect the animals’ life cycles.


Worm | 2015

Why do worms go against the flow? C. elegans behaviors explained by simple physics.

Haim H. Bau; David M. Raizen; Jinzhou Yuan

Nearly half a century of neurobiological research using the nematode Caenorahbitis elegans has produced a remarkably detailed understanding of how genotype controls behavioral phenotype. However, the role of simple physical forces in regulating behavior has been understudied. Here, we review our recent observations of 3 behaviors of C. elegans suspended in solution that can be fully explained by the laws of mechanics. These behaviors are bordertaxis, the attraction toward solid surfaces; positive rheotaxis, the propensity to swim against the flow; and synchrophilia, the tendency of animals when close to each other to synchronize their gaits. Although these 3 behaviors are not directly regulated by the animals nervous system, bordertaxis and rheotaxis require the animal to have an undulating gait. We conjecture that these behaviors are advantageous to the animals, and thus evolution may have favored microorganism that swim with an undulating gait.


Lab on a Chip | 2015

High-throughput, motility-based sorter for microswimmers such as C. elegans.

Jinzhou Yuan; Jessie Zhou; David M. Raizen; Haim H. Bau


Journal of the Royal Society Interface | 2015

A hydrodynamic mechanism for attraction of undulatory microswimmers to surfaces (bordertaxis)

Jinzhou Yuan; David M. Raizen; Haim H. Bau


Nano Letters | 2013

Orienting Actin Filaments for Directional Motility of Processive Myosin Motors

Jinzhou Yuan; Anand Pillarisetti; Yale E. Goldman; Haim H. Bau


Journal of the Royal Society Interface | 2016

Terrain following and applications: Caenorhabditis elegans swims along the floor using a bump and undulate strategy

Jinzhou Yuan; Hungtang Ko; David M. Raizen; Haim H. Bau


67th Annual Meeting of the APS Division of Fluid Dynamics | 2014

Video: Why are Undulatory Swimmers Attracted to Surfaces (Bordertaxis)?

Jinzhou Yuan; David M. Raizen; Haim H. Bau


Bulletin of the American Physical Society | 2015

High-Throughput, Motility-Based Sorter for Microswimmers and Gene Discovery Platform

Jinzhou Yuan; David M. Raizen; Haim H. Bau

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Haim H. Bau

University of Pennsylvania

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David M. Raizen

University of Pennsylvania

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Yale E. Goldman

University of Pennsylvania

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Hungtang Ko

University of Pennsylvania

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Jessie Zhou

University of Pennsylvania

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Kun He Lee

University of Pennsylvania

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Michael M. Norton

University of Pennsylvania

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Samuel Belfer

University of Pennsylvania

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