Lu H et al. (2023) Food Funct "Latilactobacillus curvatus FFZZH5L isolated from pickled cowpea enhanced antioxidant activity in Caenorhabditis elegans by upregulating the level of glutathione S-transferase."

Wang Y, Jiang F, Sun L, Lu H, Chen L, Tong S

[Food Funct, 2023]

<i>Latilactobacillus curvatus</i> is a potential probiotic that possesses beneficial health properties and fermentation traits; however, the extent of understanding of the antioxidant activities of <i>L. curvatus</i> is limited. This study investigates the antioxidant activities of a new <i>L. curvatus</i> FFZZH5L strain. The strain exhibits broad tolerance to acids, bases and salts and demonstrated good adaption to the gastrointestinal environment, with a survival rate of 45% after 24 h of treatment in artificial gastrointestinal juice. Moreover, <i>L. curvatus</i> FFZZH5L exhibits inhibitory effects on <i>Staphylococcus aureus</i>, with a self-aggregation rate of 34.8% and a co-aggregation rate of 82.2%. <i>In vitro</i>, the DPPH radical scavenging ability and GSH-px enzyme activity of <i>L. curvatus</i> FFZZH5L reach 64.27% and 15.95 U mL^-1, respectively. Treatment of <i>C. elegans</i> with <i>L. curvatus</i> FFZZH5L <i>in vivo</i> significantly extended the organism's lifespan. Furthermore, the activity of SOD, GSH-px and T-AOC was increased by 33.6%, 43.4% and 58.3%, respectively. Feeding <i>C. elegans</i> with <i>L. curvatus</i> FFZZH5L decreased the MDA, lipofuscin and ROS levels by 9%-36.4%. <i>L. curvatus</i> FFZZH5L effectively protected <i>C. elegans</i> against juglone-induced oxidative stress damage and led to a significant increase in the organism's survival under heat stress. The RT-qPCR analysis suggests that feeding <i>C. elegans</i> with <i>L. curvatus</i> FFZZH5L upregulates the expression levels of antioxidant-related genes including glutathione <i>S</i>-transferase 4 (<i>gst-4</i>), <i>gst-1</i>, <i>gst-10</i>, <i>sod-3</i>, <i>sod-5</i>, and <i>sod-10</i> in <i>C. elegans</i>. Our investigation confirms the probiotic and antioxidant properties of <i>L. curvatus</i>, indicating its potential application in functional foods and the pharmaceutical industry.

Thomas JH et al. (1994) Worm Breeder's Gazette "lin-36, a Class B Synthetic Multivulva Gene, Encodes a Novel Protein"

Thomas JH, Horvitz HR

[Worm Breeder's Gazette, 1994]

lin-36, a Class B Synthetic Multivulva Gene, Encodes a Novel Protein Jeffrey H. Thomas and H. Robert Horvitz, HHMI, Dept. Biology, MIT, Cambridge, MA 02139, USA

Lee H et al. (2014) Lab Chip "A multi-channel device for high-density target-selective stimulation and long-term monitoring of cells and subcellular features in C. elegans."

Coakley S, Lee H, Lu H, Hilliard MA, Hammarlund M, Kim SA, Mugno P

[Lab Chip, 2014]

Selective cell ablation can be used to identify neuronal functions in multicellular model organisms such as Caenorhabditis elegans. The optogenetic tool KillerRed facilitates selective ablation by enabling light-activated damage of cell or subcellular components in a temporally and spatially precise manner. However, the use of KillerRed requires stimulating (5 min-1 h), culturing (~24 h) and imaging (often repeatedly) a large number of individual animals. Current manual manipulation methods are limited by their time-consuming, labor-intensive nature, and their usage of anesthetics. To facilitate large-scale selective ablation, culturing, and repetitive imaging, we developed a densely-packed multi-channel device and used it to perform high-throughput neuronal ablation on KillerRed-expressing animals. The ability to load worms in identical locations with high loading efficiency allows us to ablate selected neurons in multiple worms simultaneously. Our device also enables continuous observation of animals for 24 h following KillerRed activation, and allows the animals to be recovered for behavioural assays. We expect this multi-channel device to facilitate a broad range of long-term imaging and selective illumination experiments in neuroscience.

Sun J et al. (2013) Exp Parasitol "Parasitism of secondary-stage juvenile of Heterodera glycines and four larva stages of Caenorhabditis elegans by Hirsutella spp."

Sun J, Xie H, Xiang M, Liu X, Qiu J

[Exp Parasitol, 2013]

The fungi Hirsutella rhossiliensis and Hirsutella minnesotensis generally parasitize only plant-parasitic nematodes in nature but parasitize the bacterivorous nematode Caenorhabditis elegans on agar plates. To establish a model system for studying the interaction between fungi and nematodes, we compared the parasitism of the first- to fourth-stage larvae (L1-L4) of C. elegans and second-stage juvenile (J2) of Heterodera glycines by twenty isolates of Hirsutella spp. Although parasitism differed substantially among isolates, both H. minnesotensis and H. rhossiliensis parasitized a higher percentage of H. glycines J2s than of C. elegans larvae. Parasitism of C. elegans L1s was correlated with parasitism of H. glycines J2s. Parasitism of C. elegans by H. rhossiliensis and H. minnesotensis was negatively correlated with larva size and motility, i.e., parasitism was higher for the younger stages. The C. elegans L1 is recommended for studying parasitism of nematodes by H. rhossiliensis and H. minnesotensis.

Aubry G et al. (2017) Lab Chip "Droplet array for screening acute behaviour response to chemicals in Caenorhabditis elegans."

Lu H, Aubry G

[Lab Chip, 2017]

Caenorhabditis elegans is an excellent model organism for studying chemosensation as a significant part of its nervous system and genome are devoted to the detection of chemical cues. Studies of decision-making, learning, mating behaviour, and intraspecies communication require measuring the acute behavioural response to chemical stimulation. Such assays require precise and repeatable chemical delivery and are often arduous when performed manually. Microfluidic platforms have been developed for chemosensation studies in C. elegans. However, these platforms lack temporal resolution in chemical delivery necessary for screening acute behaviour and cannot selectively recover animals, a necessary feature for genetic screens. Here we present a droplet array for screening acute behavioural responses of C. elegans to chemical stimulation. Using droplets enables isolating the worms and controlling the chemical environment. The chamber design of the static array allows continuous monitoring of animal behaviour. By combining a gradient of confinement and flow restriction features, we demonstrate selective and sequential trapping of multiple droplets as well as their release on demand. These functions enable repeated capture of animals, monitoring of their behaviour upon chemical stimulation and subsequent release. To demonstrate the ability to screen multiple conditions, we measured worm thrashing activity in response to different concentrations of tetramisole. To illustrate the ability to capture acute behavioural responses, we monitored the behavioural response of male to pheromone stimulation. Due to the versatility of the chamber operation and its ultra-low volume uses of reagents, we envision this platform to be highly suited to combinatorial screening and drug discovery.

Krajniak J et al. (2010) Lab Chip "Long-term high-resolution imaging and culture of C. elegans in chip-gel hybrid microfluidic device for developmental studies."

Krajniak J, Lu H

[Lab Chip, 2010]

Developmental studies in multicellular model organisms such as Caernohabditis elegans rely extensively on the ability to cultivate and image animals repeatedly at the cell or subcellular level. However, standard high-resolution imaging techniques require the use of anaesthetics for immobilization, and may have undesirable side effects on development. Thus such techniques are not ideal in allowing the same animals to grow and be imaged throughout development to observe specific developmental processes. In this paper, we present a microfluidic system designed to overcome these difficulties. The system allows for long-term culture of C. elegans starting at L1 larval stage and repeated high-resolution imaging at physiological temperatures without using anaesthetics. We use a commercially available biocompatible polymer, Pluronic F127 for immobilization; this polymer is capable of a reversible thermo-sensitive sol-gel transition within approximately 2 degrees C, which is well-controlled in the microfluidic chip. The gel phase is sufficient to immobilize the animals. While animals are not imaged, they are cultured in individual chambers in media containing nutrients required for development. We show here that this method facilitates time-lapse studies of single animals at high-resolution and lends itself to live imaging experiments on developmental processes and dynamic events.

Calhoun, W.A. et al. (2019) International Worm Meeting "An open-top light sheet microscope with remote focusing for imaging neural activity of C. elegans in microfluidics."

Calhoun, W.A., Lu, H.

[International Worm Meeting, 2019]

Whole brain imaging of C. elegans holds incredible potential for investigating how nervous systems integrate sensory input and drive behavior. This is particularly true with the application of microfluidics to precisely manipulate worms' sensory environment. However, collecting high-quality volumetric images with sufficient speed to track individual neurons as a worm moves and deforms tests the limits of optical microscopy. Light sheet microscopy has proven to have several advantages for high-speed volumetric imaging, including low light exposure and high collection efficiency, which make it ideal for imaging small, transparent specimens. However, the geometry of conventional light sheet microscopes requires that the sample be suspended in the small volume between the separate illumination and detection objectives. This renders these microscopes incompatible with microfluidics, agarose pads, or any other planar sample mounting which would be physically blocked by the objectives. We present an open-top light sheet microscope capable of fast volumetric imaging that is compatible with planar microfluidics and demonstrate its utility for recording neural activity in C. elegans. This design uses remote focusing with an electrically tunable lens to rapidly reposition the image plane without physically moving the detection objective, enabling acquisition at camera-limited volume rates. We show that multi-channel fluorescence imaging at 10+ volumes/second with light sheet microscopy improves whole brain calcium imaging and reduces motion artifacts. We also demonstrate its ability to record fine anatomical features during mechanical stimulation through microfluidics.

Chung K et al. (2009) Lab Chip "Automated high-throughput cell microsurgery on-chip."

Chung K, Lu H

[Lab Chip, 2009]

Laser cell kill is an established tool for studying cells' roles during development and behavior, but its use has been limited due to the manual and low-throughput nature. We demonstrate here a technique combining multiplexing microfluidic manipulation of Caenorhabditis elegans and software for image processing and automation, allowing for high-throughput cell ablations.

Krajniak J et al. (2010) Neuronal Development, Synaptic Function and Behavior, Madison, WI "Repeated High-Resolution Long-Term Imaging without Anesthetics Using Microfluidics and Thermally Controllable Gels"

Lu H, Krajniak J

[Neuronal Development, Synaptic Function and Behavior, Madison, WI, 2010]

Tracking development of individual animals can provide insights into dynamics of processes such as synaptogenesis, synaptic re-arrangement, and axonal growth cone development. However, such longitudinal studies are experimentally complicated and sometimes impossible to perform on the basis of individual worms; this is largely due to negative effects of anaesthetics on physiology and development and the difficulty of keeping track of individual worms. We developed a platform to i) repeatedly immobilize animals at physiological temperature and conditions, ii) perform high-magnification imaging while keeping track of individual specimen, and iii) culture animals between imaging cycles for proper development for days. The platform is based on the thermo-reversible sol-gel transition of a polymer solution (within 1 degree Celcius), which is used for the reversible immobilization of animals. A microfluidic system is used in conjunction for animal trapping, nutrient delivery, and fluid and precise temperature control. Worm embryos are trapped in individual chambers via connected embryo traps. Gentle flow of M9 with OP50 bacteria and cholesterol is delivered into each chamber, allowing animals to feed and develop while trapping them inside the chamber. Precise temperature modulation by integrated microelectrodes controls the sol-gel transition for immobilization; the devices are ease to set up, re-usable, and economical. During immobilization, the gel exerts uniform pressure along the animal body, and thus leads to negligible physical deformation. Image quality (e.g. amount of diffraction, photo-bleaching) when using the gel is comparable to that of standard methods with anaesthetics. We have verified the gel's biocompatibility with C. elegans; repeated and long-term exposure and immobilization show no effect on measured physiological traits such as pharyngeal pumping rate, number of progeny, and time to reach egg-laying. We tested the functionality of our system by monitoring the re-arrangement of synaptic connections of the six GABAergic motor neurons at the end of the L1 larval stage (Hallam and Jin, Nature, 1998). To our knowledge, our platform is the only system to date that facilitates longitudinal studies in the early stages of development on an individual-animal basis. It is also the first to enable live imaging of short-term (order of seconds) to long-term (hours and days) developmental events at arbitrary intervals on a single device.

Aubry G et al. (2014) Biomicrofluidics "A perspective on optical developments in microfluidic platforms for Caenorhabditis elegans research."

Aubry G, Lu H

[Biomicrofluidics, 2014]

Microfluidics offers unique ways of handling and manipulating microorganisms, which has particularly benefited Caenorhabditis elegans research. Optics plays a major role in these microfluidic platforms, not only as a read-out for the biological systems of interest but also as a vehicle for applying perturbations to biological systems. Here, we describe different areas of research in C. elegans developmental biology and behavior neuroscience enabled by microfluidics combined with the optical components. In particular, we highlight the diversity of optical tools and methods in use and the strategies implemented in microfluidics to make the devices compatible with optical techniques. We also offer some thoughts on future challenges in adapting advancements in optics to microfluidic platforms.