R.BZ. is supported by the EMBO long term fellowship and The Larry L. Hillblom Foundation. R.H.S is supported by grant 5F32AG032023-02 through the National Institute of Aging (NIA) and the Glenn Foundation for Medical Research Postdoctoral Fellowship. A.F. is supported by grant F32AG051355 through the NIA. H.K.G. is supported by grant DGE1752814 through the National Science Foundation Graduate Research Fellowship Program. M.G.M. is supported by 1F31AG060660-01 through NIA. A.D. is supported by the Thomas and Stacey Siebel Foundation, the Howard Hughes Medical Institute, and 4R01AG042679-04 and 5R01AG055891-02 from NIA, and 5R01ES021667-09 from NIEHS. We thank Larry Joe, Melissa Sanchez, Naame Kelet, and Anel Esquivel for significant technical assistance. We thank the Morimoto lab and the CGC (funded by NIH Office of Research Infrastructure Program P40 OD010440) for strains.

The authors have nothing to disclose.

Here, methods to interrogate cellular stress responses in C. elegans, using fluorescent transcriptional reporters and physiological stress survival assays are described. The reporters all utilize GFP expression driven under the promoter of a downstream transcriptional target of the transcription factors involved in mounting cellular stress responses. The use of hsp-4p::GFP modulated by XBP-1s-mediated UPRER, hsp-6p::GFP controlled by ATFS-1-mediated UPRMT, gst-4p::GFP<...

The ability of an organism to respond to changes in the intra- and extracellular environment is crucial for its survival and adaptation. This is accomplished on a cellular level through numerous protective pathways that ensure the integrity of the cell. While numerous cellular components are subject to stress-associated damage, one major involvement of cellular stress responses is to repair and protect the homeostasis of the cellular proteome. However, the compartmentalization of proteins into special structures, called organelles, poses a challenge for the cell, as it cannot rely on one centralized form of protein quality control to ensure that all the proteins within the cell are properly folded and functional. Therefore, to deal with perturbations to their proteins, organelles have evolved dedicated quality control mechanisms, which can sense misfolded proteins and activate a stress response in an attempt to alleviate the stress within that compartment. For example, the cytosol relies on the heat shock response (HSR), while the endoplasmic reticulum (ER) and mitochondria rely on their compartment-specific unfolded protein responses (UPR). The OxSR serves to alleviate the toxic effects of reactive oxygen species (ROS). Each stress response is triggered in the presence of cellular challenges and environmental insults and induces a tailored transcriptional response. The hallmarks of these responses include synthesizing molecules that re-fold misfolded proteins (such as chaperones) targeted to the proper organelle, or alternatively, remove damaged proteins by protein degradation. Failure to activate these stress responses results in accumulation of damaged proteins, cellular dysfunction propagated to systemic failure of tissues, and eventually death of the organism. The function and regulation of the different stress responses are reviewed elsewhere1.
Many insights regarding the regulation and activity of cellular stress responses have been attributed to the nematode, Caenorhabditis elegans, a multicellular model organism in genetic research. Nematodes not only allow studying the activation of stress responses on the cellular level, but also on the organismal level; nematodes have been used to study the effects of genetic perturbations or exposure to drugs and pollutants on their growth and survival. Their quick generation time, isogeny, transparency, genetic tractability, and ease of use during experimentation make them ideal for such studies. Additionally, the relatively quick physiological response to stress (between hours and a few days) and the evolutionary conservation of cellular pathways make nematodes a prominent tool in studying stress resistance.
There are two commonly used E. coli strains used as a food source to grow C. elegans: standard OP50, a B strain in which most experimentation has been historically performed2 and HT115, a K-12 strain that is used for almost all RNAi experiments3,4. It is important to note that there are significant differences between OP50 and HT115 bacterial diets. Growth on these different bacterial sources has been shown to cause major differences in metabolic profile, mitochondrial DNA copy number, and several major phenotypes, including lifespan5. Some of these differences are attributed to Vitamin B12 deficiency associated with growth on OP50 bacteria, which can result in defects in mitochondrial homeostasis and increased sensitivity to pathogens and stresses. All of these phenotypes have been shown to be alleviated by growth on HT115 bacteria, which have higher levels of Vitamin B126. Therefore, it is recommended that all experiments on physiological stress responses be performed on HT115 bacteria, regardless of the necessity of RNAi conditions. However, due to the ease of maintaining animals on OP50, all standard growth (i.e., maintenance and amplification of animals) can be performed on OP50, as significant differences in the experimental paradigms described here were not detected in worms maintained on OP50 as long as they were moved to HT115 post synchronization (i.e., from hatch post-bleaching with or without L1 arresting) until experimentation.
Here, the characterization of the activity of cellular stress responses using two functional methods is described. It should be noted that the protocols presented are primarily focused on cellular stress responses and their impact on protein homeostasis. First, fluorescent transcriptional reporters are utilized, which are regulated by endogenous gene promoters that are specifically activated in response to different cellular stresses. These fluorescent transcriptional reporters are based on the transcriptional induction of specific genes that are natively part of the stress response. For example, HSP-4, a heat shock protein orthologous to the human chaperone HSPA5/BiP, is activated upon ER-stress and localizes to the ER to alleviate the stress. In conditions of ER stress (e.g., exposure to tunicamycin), a green fluorescent protein (GFP), placed under the regulation of the hsp-4 promoter, is synthesized in high levels as can be assessed by fluorescent microscopy or quantitatively measured using large-particle flow cytometry of nematodes7. Similarly, the promoter of a mitochondrial chaperone, hsp-6 (orthologous to mammalian HSPA9), is utilized to monitor the activation of the UPRMT8, and the promoter of the cytosolic chaperone hsp-16.2 (orthologous to the human crystallin alpha genes) is used for assessing the activity of the HSR9. These reporters allow a rapid characterization of the pathways activated in response to various perturbations.
Often, the reporters presented here are imaged using microscopy, which provides a qualitative output of the activation of stress responses. However, while imaging techniques provide both information on intensity and tissue location of the reporters described above, its quantification is not always accurate or robust. While it is possible to quantify fluorescent activation using imaging analysis tools, these methods are relatively low throughput and sample size is small, due to the relatively low number of animals imaged. The ease and ability to obtain large quantities of animals quickly make C. elegans an ideal model system to assay the activation of fluorescent stress reporters through the use of a large particle flow cytometer. A large-particle flow cytometer is capable of recording, analyzing, and sorting based on size and fluorescence from many live animals. Using this method, it is possible to get the fluorescent intensity, size, and also spatial (2D) information for thousands of worms. The system is controlled using FlowPilot, which allows for real-time data acquisition and analysis of the measured parameters. Here, methods for both microscopic imaging and quantitative analysis using a large-particle flow cytometer are offered as methods to measure the activation of stress responses.
Beyond reporter analysis, the sensitivity or resistance of animals to stress can be measured using physiological stress assays. This is achieved by exposing animals to stressful environments that activate specific cellular stress pathways. Here, several methods are provided to measure sensitivity of whole animals to specific types of stressors.
ER stress is applied to C. elegans by using the chemical agent, tunicamycin, which blocks N-linked glycosylation, causing accumulation of misfolded proteins in the ER10. In C. elegans, growth upon exposure to tunicamycin results in major perturbations in ER function, and a significantly decreased lifespan11. By measuring the survival of animals on tunicamycin-containing plates, ER stress sensitivity of animals can be quantified. For example, animals with ectopic UPRER induction and thus increased resistance to protein misfolding stress in the ER have an increased survival upon tunicamycin exposure compared to wild-type animals12.
Oxidative and mitochondrial stress is applied to C. elegans by exposing animals to the chemical agent, paraquat. Paraquat is a commonly used herbicide, which causes superoxide formation specifically in the mitochondria13. Due to the specific localization of mitochondria-derived reactive oxygen species (ROS), paraquat assays are often used as a &#34;mitochondrial&#34; stress assay. However, superoxide is rapidly converted into hydrogen peroxide by mitochondrial superoxide dismutases (SODs)14. Hydrogen peroxide can subsequently diffuse out of the mitochondria and cause oxidative stress in other compartments of the cell. Therefore, we describe paraquat survival assays as measuring sensitivity to both mitochondrial and oxidative stress (other oxidative stress assays can be found15).
Thermotolerance assays are performed in C. elegans by placing animals in elevated temperatures. Ambient temperatures for nematodes are ~15-20 &#176;C and thermal stress is induced at temperatures above 25 &#176;C16,17. Thermotolerance assays are generally performed at temperatures ranging from 30-37 &#176;C, as animals exhibit major cellular defects at this temperature, and survival assays are completed within 24 hours16,18. Here, two alternative methods are provided for performing thermotolerance assays: growth at 34 &#176;C and growth at 37 &#176;C. Together, the protocols presented here can be utilized to perform large-scale screens when combined with standard gene knock-down using RNA interference or chemical drug libraries.
The protocol can be broken into 4 broad procedures- growth of C. elegans and preparation for imaging (sections 1 and 2), imaging of transcriptional reporters using fluorescent microscopy (sections 3-5), quantitative measurements of reporters using a large-particle flow cytometer (section 6), and physiological assays to measure stress sensitivity in C. elegans (section 7).

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Antimycin A</td>
			<td>Sigma-Aldrich</td>
			<td>A8674</td>
			<td>for mitochondrial stress</td>
		</tr>
		<tr>
			<td>Bacto Peptone</td>
			<td>Fisher Scientific</td>
			<td>DF0118072</td>
			<td>for NGM plates</td>
		</tr>
		<tr>
			<td>BD Difco granulated agar</td>
			<td>VWR</td>
			<td>90000-782</td>
			<td>for NGM plates</td>
		</tr>
		<tr>
			<td>Calcium chloride dihydrate</td>
			<td>VWR</td>
			<td>97061-904</td>
			<td>for NGM plates</td>
		</tr>
		<tr>
			<td>Carbenicillin</td>
			<td>BioPioneer</td>
			<td>C0051-25</td>
			<td>for RNAi</td>
		</tr>
		<tr>
			<td>Cholesterol</td>
			<td>Sigma-Aldrich</td>
			<td>57-88-5</td>
			<td>for NGM plates</td>
		</tr>
		<tr>
			<td>COPAS Biosorter</td>
			<td>Union Biometrica</td>
			<td>350-5000-000</td>
			<td>equipped with a 488 nm light source.</td>
		</tr>
		<tr>
			<td>COPAS Cleaning Solution</td>
			<td>Union Biometrica</td>
			<td>300-5072-000</td>
			<td>to use with COPAS</td>
		</tr>
		<tr>
			<td>COPAS Sheath Solution</td>
			<td>Union Biometrica</td>
			<td>300-5070-100</td>
			<td>to use with COPAS</td>
		</tr>
		<tr>
			<td>DMSO</td>
			<td>Sigma-Aldrich</td>
			<td>472301</td>
			<td>solvent for drugs</td>
		</tr>
		<tr>
			<td>IPTG dioxane free</td>
			<td>Denville Scientific</td>
			<td>CI8280-4</td>
			<td>for RNAi</td>
		</tr>
		<tr>
			<td>LB Broth Miller</td>
			<td>Fisher Scientific</td>
			<td>BP1426500</td>
			<td>for LB</td>
		</tr>
		<tr>
			<td>M205FA stereoscope</td>
			<td>Leica</td>
			<td>10450040</td>
			<td>equipped with a Leica DFC3000G monochromatic CCD camera, standard Leica GFP filter (ex 395-455, EM 480 LP), and LAS X software</td>
		</tr>
		<tr>
			<td>Magnesium sulfate heptahydrate</td>
			<td>VWR</td>
			<td>EM-MX0070-3</td>
			<td>for NGM plates, M9</td>
		</tr>
		<tr>
			<td>Paraquat</td>
			<td>Sigma-Aldrich</td>
			<td>36541</td>
			<td>for oxidative/mitochondrial stress</td>
		</tr>
		<tr>
			<td>Potassium Chloride</td>
			<td>Fisher</td>
			<td>P217-500</td>
			<td>for bleach soluton</td>
		</tr>
		<tr>
			<td>Potassium phosphate dibasic</td>
			<td>VWR</td>
			<td>EM-PX1570-2</td>
			<td>for NGM plates</td>
		</tr>
		<tr>
			<td>Potassium phosphate monobasic</td>
			<td>VWR</td>
			<td>EM-PX1565-5</td>
			<td>for M9</td>
		</tr>
		<tr>
			<td>Revolve</td>
			<td>ECHO</td>
			<td>75990-514</td>
			<td>equipped with an Olympus 4x Plan Fluorite NA 0.13 objective lens, standard Olympus FITC filter (ex 470/40; em 525/50; DM 560), and an iPad Pro for camera and to drive ECHO software</td>
		</tr>
		<tr>
			<td>Sodium Azide</td>
			<td>Sigma-Aldrich</td>
			<td>71289-50G</td>
			<td>for imaging</td>
		</tr>
		<tr>
			<td>Sodium Chloride</td>
			<td>EMD Millipore</td>
			<td>SX0420-5</td>
			<td>for NGM plates, M9</td>
		</tr>
		<tr>
			<td>Sodium phosphate dibasic</td>
			<td>VWR</td>
			<td>71003-472</td>
			<td>for M9</td>
		</tr>
		<tr>
			<td>Tert-butyl hydroperoxide</td>
			<td>Sigma-Aldrich</td>
			<td>458139</td>
			<td>for oxidative stress</td>
		</tr>
		<tr>
			<td>Tetracycline hydrochloride</td>
			<td>Sigma-Aldrich</td>
			<td>T7660-5G</td>
			<td>for RNAi</td>
		</tr>
		<tr>
			<td>Tunicamycin</td>
			<td>Sigma-Aldrich</td>
			<td>T7765-50MG</td>
			<td>for ER stress</td>
		</tr>
	</tbody>
</table>

measurements of physiological stress responses in c. elegans

Organisms are often exposed to fluctuating environments and changes in intracellular homeostasis, which can have detrimental effects on their proteome and physiology. Thus, organisms have evolved targeted and specific stress responses dedicated to repair damage and maintain homeostasis. These mechanisms include the unfolded protein response of the endoplasmic reticulum (UPRER), the unfolded protein response of the mitochondria (UPRMT), the heat shock response (HSR), and the oxidative stress response (OxSR). The protocols presented here describe methods to detect and characterize the activation of these pathways and their physiological consequences in the nematode, C. elegans. First, the use of pathway-specific fluorescent transcriptional reporters is described for rapid cellular characterization, drug screening, or large-scale genetic screening (e.g., RNAi or mutant libraries). In addition, complementary, robust physiological assays are described, which can be used to directly assess sensitivity of animals to specific stressors, serving as functional validation of the transcriptional reporters. Together, these methods allow for rapid characterization of the cellular and physiological effects of internal and external proteotoxic perturbations.

Using transcriptional reporters to measure activation of stress responses 
Here, fluorescent transcriptional reporters are used, which serve as robust tools to measure activation of most stress responses in C. elegans. GFP expression is driven under the promoter of canonical targets of master transcriptional regulators involved in responding to compartment-specific stresses. A comprehensive list of commonly used transcriptional reporters is available in <str...

Watch this Scientific Journal Video about Measurements of Physiological Stress Responses in C. Elegans at JoVE.com

Measurements of Physiological Stress Responses in C. Elegans

Here, we characterize cellular proteotoxic stress responses in the nematode C. elegans by measuring the activation of fluorescent transcriptional reporters and assaying sensitivity to physiological stress.

Measurements of Physiological Stress Responses in C. Elegans

Organisms are often exposed to fluctuating environments and changes in intracellular homeostasis, which can have detrimental effects on their proteome and ...

measurements-of-physiological-stress-responses-in-c-elegans

Research

JoVE Journal

Biology

13.7K Views.  University of California, Berkeley. Here, we characterize cellular proteotoxic stress responses in the nematode C. elegans by measuring the activation of fluorescent transcriptional reporters and assaying sensitivity to physiological stress.

Video: Measurements of Physiological Stress Responses in C. Elegans

Generation of Stable Transgenic C. elegans Using Microinjection

Transgenic Caenorhabditis elegans can be readily created via microinjection of a DNA plasmid solution into the gonad 1. The plasmid DNA rearranges to form extrachromosomal concatamers that are stably inherited, though not with the same efficiency as actual chromosomes 2. A gene of interest is co-injected with an obvious phenotypic marker, such as rol-6 or GFP, to allow selection of transgenic animals under a dissecting microscope. The exogenous gene may be expressed from its native promoter for cellular localization studies. Alternatively, the transgene can be driven by a different tissue-specific promoter to assess the role of the gene product in that particular cell or tissue. This technique efficiently drives gene expression in all tissues of C. elegans except for the germline or early embryo 3. Creation of transgenic animals is widely utilized for a range of experimental paradigms. This video demonstrates the microinjection procedure to generate transgenic worms. Furthermore, selection and maintenance of stable transgenic C. elegans lines is described.

This video demonstrates the technique of microinjection into the gonad of C. elegans to create transgenic animals.

Transgenic Caenorhabditis elegans can be readily created via microinjection of a DNA plasmid solution into the gonad 1.  The plasmid DNA rearranges to ...

Monitoring Plant Hormones During Stress Responses

Plant hormones and related signaling compounds play an important role in the regulation of plant responses to various environmental stimuli and stresses. Among the most severe stresses are insect herbivory, pathogen infection, and drought stress. For each of these stresses a specific set of hormones and/or combinations thereof are known to fine-tune the responses, thereby ensuring the plant's survival. The major hormones involved in the regulation of these responses are jasmonic acid (JA), salicylic acid (SA), and abscisic acid (ABA). To better understand the role of individual hormones as well as their potential interaction during these responses it is necessary to monitor changes in their abundance in a temporal as well as in a spatial fashion. For the easy, sensitive, and reproducible quantification of these and other signaling compounds we developed a method based on vapor phase extraction and gas chromatography/mass spectrometry (GC/MS) analysis (1, 2, 3, 4). After extracting these compounds from the plant tissue by acidic aqueous 1-propanol mixed with dichloromethane the carboxylic acid-containing compounds are methylated, volatilized under heat, and collected on a polymeric absorbent. After elution into a sample vial the analytes are separated by gas chromatography and detected by chemical ionization mass spectrometry. The use of appropriate internal standards then allows for the simple quantification by relating the peak areas of analyte and internal standard.

A simple method is provided that allows for the rapid extraction and analysis of multiple plant hormones from small tissue samples. The procedure uses vapor phase extraction as the solemn purification step. Samples are analyzed by GC/MS with chemical ionization that produces mainly (M+1)+ ions.

Plant hormones and related signaling compounds play an important role in the regulation of plant responses to various environmental stimuli and stresses. ...

Generation of Transgenic C. elegans by Biolistic Transformation

The number of laboratories using the free living nematode C. elegans is rapidly growing. The popularity of this biological model is attributed to a rapid generation time and short life span, easy and inexpensive maintenance, fully sequenced genome, and array of RNAi resources and mutant animals. Additionally, analysis of the C. elegans genome revealed a great similarity between worms and higher vertebrates, which suggests that research in worms could be an important adjunct to studies performed in whole mice or cultured cells. A powerful and important part of worm research is the ability to use transgenic animals to study gene localization and function. Transgenic animals can be created either via microinjection of the worm germline or through the use of biolistic bombardment. Bombardment is a newer technique and is less familiar to a number of labs. Here we describe a simple protocol to generate transgenic worms by biolistic bombardment with gold particles using the Bio-Rad PDS-1000 system. Compared with DNA microinjection into hermaphrodite germline, this protocol has the advantage of not requiring special skills from the operator with regards to identifying worm anatomy or performing microinjection. Further multiple transgenic lines are usually obtained from a single bombardment. Also in contrast to microinjection, biolistic bombardment produces transgenic animals with both extrachromosomal arrays and integrated transgenes. The ability to obtain integrated transgenic lines can avoid the use of mutagenic protocols to integrate foreign DNA. In conclusion, biolistic bombardment can be an attractive method for the generation of transgenic animals, especially for investigators not interested in investing the time and effort needed to become skilled at microinjection.

Generation of Transgenic C. elegans by Biolistic Transformation

Transgenic worms are commonly used in C. elegans research. Described is a simple, yet effective, protocol to introduce transgenes into worms using biolistic bombardment with DNA-coated gold particles. The effort involved and results of bombardment compare favorably with microinjection for the generation of transgenic animals.

The number of laboratories using the free living nematode C. elegans is rapidly growing. The popularity of this biological model is attributed to a rapid ...

RNAi Screening to Identify Postembryonic Phenotypes in C. elegans

C. elegans has proven to be a valuable model system for the discovery and functional characterization of many genes and gene pathways1. More sophisticated tools and resources for studies in this system are facilitating continued discovery of genes with more subtle phenotypes or roles. 
Here we present a generalized protocol we adapted for identifying C. elegans genes with postembryonic phenotypes of interest using RNAi2. This procedure is easily modified to assay the phenotype of choice, whether by light or fluorescence optics on a dissecting or compound microscope. This screening protocol capitalizes on the physical assets of the organism and molecular tools the C. elegans research community has produced. As an example, we demonstrate the use of an integrated transgene that expresses a fluorescent product in an RNAi screen to identify genes required for the normal localization of this product in late stage larvae and adults. First, we used a commercially available genomic RNAi library with full-length cDNA inserts. This library facilitates the rapid identification of multiple candidates by RNAi reduction of the candidate gene product. Second, we generated an integrated transgene that expresses our fluorecently tagged protein of interest in an RNAi-sensitive background. Third, by exposing hatched animals to RNAi, this screen permits identification of gene products that have a vital embryonic role that would otherwise mask a post-embryonic role in regulating the protein of interest. Lastly, this screen uses a compound microscope equipped for single cell resolution.

RNAi Screening to Identify Postembryonic Phenotypes in C. elegans

We describe a sensitized method to identify postembryonic regulators of protein expression and localization in C. elegans using an RNAi-based genomic screen and an integrated transgene that expresses a functional, fluorescently tagged protein.

C. elegans has proven to be a valuable model system for the discovery and functional characterization of many genes and gene pathways1. More sophisticated ...

C. elegans Chemotaxis Assay

Many organisms use chemotaxis to seek out food sources, avoid noxious substances, and find mates. Caenorhabditis elegans has impressive chemotaxis behavior.
 The premise behind testing the response of the worms to an odorant is to place them in an area and observe the movement evoked in response to an odorant. Even with the many available assays, optimizing worm starting location relative to both the control and test areas, while minimizing the interaction of worms with each other, while maintaining a significant sample size remains a work in progress 1-10. The method described here aims to address these issues by modifying the assay developed by Bargmann et al.1. A Petri dish is divided into four quadrants, two opposite quadrants marked "Test" and two are designated "Control". Anesthetic is placed in all test and control sites. The worms are placed in the center of the plate with a circle marked around the origin to ensure that non-motile worms will be ignored. Utilizing a four-quadrant system rather than one 2 or two 1 eliminates bias in the movement of the worms, as they are equidistant from test and control samples, regardless of which side of the origin they began. This circumvents the problem of worms being forced to travel through a cluster of other worms to respond to an odorant, which can delay worms or force them to take a more circuitous route, yielding an incorrect interpretation of their intended path. This method also shows practical advantages by having a larger sample size and allowing the researcher to run the assay unattended and score the worms once the allotted time has expired.

C. elegans Chemotaxis Assay

A method of quantitatively evaluating the chemotactic response of Caenorhabditis elegans is described. A chemotactic index (CI) was employed as a way to precisely evaluate the response of worms to certain targets, and serve as a platform of comparison between strains and compounds of interest.

Many organisms use chemotaxis to seek out food sources, avoid noxious substances, and find mates.  Caenorhabditis elegans has impressive chemotaxis ...

Antibody Staining in C. Elegans Using &quot;Freeze-Cracking&quot;

To stain C. elegans with antibodies, the relatively impermeable cuticle must be bypassed by chemical or mechanical methods. "Freeze-cracking" is one method used to physically pull the cuticle from nematodes by compressing nematodes between two adherent slides, freezing them, and pulling the slides apart. Freeze-cracking provides a simple and rapid way to gain access to the tissues without chemical treatment and can be used with a variety of fixatives. However, it leads to the loss of many of the specimens and the required compression mechanically distorts the sample. Practice is required to maximize recovery of samples with good morphology. Freeze-cracking can be optimized for specific fixation conditions, recovery of samples, or low non-specific staining, but not for all parameters at once. For antibodies that require very hard fixation conditions and tolerate the chemical treatments needed to chemically permeabilize the cuticle, treatment of intact nematodes in solution may be preferred. If the antibody requires a lighter fix or if the optimum fixation conditions are unknown, freeze-cracking provides a very useful way to rapidly assay the antibody and can yield specific subcellular and cellular localization information for the antigen of interest.

Antibody Staining in C. Elegans Using "Freeze-Cracking"

"Freeze-cracking," a method for exposing the inner tissues of the nematode C. elegans to antibodies for protein localization, is demonstrated.

To stain C.  elegans with antibodies, the relatively impermeable cuticle must be  bypassed by chemical or mechanical methods.  "Freeze-cracking" is one ...

An Anoxia-starvation Model for Ischemia/Reperfusion in C. elegans

Protocols for anoxia/starvation in the genetic model organism C. elegans simulate ischemia/reperfusion. Worms are separated from bacterial food and placed under anoxia for 20 hr&#160;(simulated ischemia), and subsequently moved to a normal atmosphere with food (simulated reperfusion). This experimental paradigm results in increased death and neuronal damage, and techniques are presented to assess organism viability, alterations to the morphology of touch neuron processes, as well as touch sensitivity, which represents the behavioral output of neuronal function. Finally, a method for constructing hypoxic incubators using common kitchen storage containers is described. The addition of a mass flow control unit allows for alterations to be made to the gas mixture in the custom incubators, and a circulating water bath allows for both temperature control and makes it easy to identify leaks. This method provides a low cost alternative to commercially available units.

An Anoxia-starvation Model for Ischemia/Reperfusion in C. elegans

A protocol is described that uses anoxia/starvation in C. elegans to model ischemia/reperfusion. Functional outcomes include increased mortality, visible abnormalities in GFP-labeled neuronal processes, and impaired behavioral responses that require neuronal function.

Protocols for anoxia/starvation in the genetic model organism C. elegans simulate ischemia/reperfusion. Worms are separated from bacterial food and placed ...

Methods for Skin Wounding and Assays for Wound Responses in C. elegans

The C. elegans epidermis and cuticle form a simple yet sophisticated skin layer that can repair localized damage resulting from wounding. Studies of wound responses and repair in this model have illuminated our understanding of the cytoskeletal and genomic responses to tissue damage. The two most commonly used methods to wound the C. elegans adult skin are pricks with microinjection needles, and local laser irradiation. Needle wounding locally disrupts the cuticle, epidermis, and associated extracellular matrix, and may also damage internal tissues. Laser irradiation results in more localized damage. Wounding triggers a succession of readily assayed responses including elevated epidermal Ca2+ (seconds-minutes), formation and closure of an actin-containing ring at the wound site (1-2 hr), elevated transcription of antimicrobial peptide genes (2-24 hr), and scar formation. Essentially all wild type adult animals survive wounding, whereas mutants defective in wound repair or other responses show decreased survival. Detailed protocols for needle and laser wounding, and assays for quantitation and visualization of wound responses and repair processes (Ca dynamics, actin dynamics, antimicrobial peptide induction, and survival) are presented.

Methods for Skin Wounding and Assays for Wound Responses in C. elegans

The adult C. elegans skin is a tractable model for studies of epithelial wound responses, including wound closure, scar formation, and innate immunity.

The C. elegans epidermis and cuticle form a simple yet sophisticated skin layer that can repair localized damage resulting from wounding. Studies of wound ...

Methods to Assess Subcellular Compartments of Muscle in C. elegans

Muscle is a dynamic tissue that responds to changes in nutrition, exercise, and disease state. The loss of muscle mass and function with disease and age are significant public health burdens. We currently understand little about the genetic regulation of muscle health with disease or age. The nematode C. elegans is an established model for understanding the genomic regulation of biological processes of interest. This worm&#8217;s body wall muscles display a large degree of homology with the muscles of higher metazoan species. Since C. elegans is a transparent organism, the localization of GFP to mitochondria and sarcomeres allows visualization of these structures in vivo. Similarly, feeding animals cationic dyes, which accumulate based on the existence of a mitochondrial membrane potential, allows the assessment of mitochondrial function in vivo. These methods, as well as assessment of muscle protein homeostasis, are combined with assessment of whole animal muscle function, in the form of movement assays, to allow correlation of sub-cellular defects with functional measures of muscle performance. Thus, C. elegans provides a powerful platform with which to assess the impact of mutations, gene knockdown, and/or chemical compounds upon muscle structure and function. Lastly, as GFP, cationic dyes, and movement assays are assessed non-invasively, prospective studies of muscle structure and function can be conducted across the whole life course and this at present cannot be easily investigated in vivo in any other organism.

Methods to Assess Subcellular Compartments of Muscle in C. elegans

Skeletal muscle is essential for locomotion and is the bodies&#8217; main protein store. Muscle health measurements within C. elegans are described. Prospective changes to muscle structure and function are assessed using localized GFP and cationic dyes.

Muscle is a dynamic tissue that responds to changes in nutrition, exercise, and disease state. The loss of muscle mass and function with disease and age ...

Measuring Oxidative Stress Resistance of Caenorhabditis elegans in 96-well Microtiter Plates

Oxidative stress, which is the result of an imbalance between production and detoxification of reactive oxygen species, is a major contributor to chronic human disorders, including cardiovascular and neurodegenerative diseases, diabetes, aging, and cancer. Therefore, it is important to study oxidative stress not only in cell systems but also using whole organisms. C. elegans is an attractive model organism to study the genetics of oxidative stress signal transduction pathways, which are highly evolutionarily conserved.
Here, we provide a protocol to measure oxidative stress resistance in C. elegans in liquid. Briefly, ROS-inducing reagents such as paraquat (PQ) and H2O2 are dissolved in M9 buffer, and solutions are aliquoted in the wells of a 96 well microtiter plate. Synchronized L4/young adult C. elegans animals are transferred to the wells (5-8 animals/well) and survival is measured every hour until most worms are dead. When performing an oxidative stress resistance assay using a low concentration of stressors in plates, aging might influence the behavior of animals upon oxidative stress, which could lead to an incorrect interpretation of the data. However, in the assay described herein, this problem is unlikely to occur since only L4/young adult animals are being used. Moreover, this protocol is inexpensive and results are obtained in one day, which renders this technique attractive for genetic screens. Overall, this will help to understand oxidative stress signal transduction pathways, which could be translated into better characterization of oxidative stress-associated human disorders.

Measuring Oxidative Stress Resistance of Caenorhabditis elegans in 96-well Microtiter Plates

C. elegans is an attractive model organism to study signal transduction pathways involved in oxidative stress resistance. Here we provide a protocol to measure oxidative stress resistance of C. elegans animals in liquid phase, using several oxidizing agents in 96 well plates.

Oxidative stress, which is the result of an imbalance between production and detoxification of reactive oxygen species, is a major contributor to chronic ...