The nematode Caenorhabditis elegans has been widely used and accelerated the discovery of new genes crucial to keeping organismic metabolic homeostasis, due to a majority of conserved metabolic principles between nematodes and humans. Various methods are exploited to assess the metabolic state in C. elegans. Since a large number of animals are required and tend to be conducted as bulk analyses of whole worm homogenates, detailed studies of metabolic changes in specific worm tissues are largely hindered. Herein, we have developed a systematic platform for analyses of morphological and metabolic changes on tissue level in C. elegans, including wild type and various mutant strains. Well-established histochemical methods combining with worms fresh frozen series sections are adapted to our platform.

Service offerings

One of the attractive characters of C. elegans, a powerful model system, is that despite its simplicity, it has defined tissues. The nematode is often described as a concentric tube and the epidermis encloses a pseudocoelomic fluid-filled cavity housing the main organ systems, including digestive, reproductive, and excretory systems. Moreover, inside the epidermis are the bands of muscle, which control the movement of the organism. Previous studies have indicated that sectional histology can be applied to define novel phenotypes in C. elegans. Herein, we adopt enzyme histochemistry and other staining methods combined with fresh frozen serial sections to analyze nematodes metabolism. These protocols may serve as a diagnostic toolbox to provide a comprehensive picture of the metabolic state of a single worm and make a positive influence in understanding metabolic changes in C. elegans.

Morphology assessment

As a most widely used medical staining technique, hematoxylin and eosin (H&E) staining gives a good overview of general and detailed morphology, and is thereby often utilized as a reference for other dyes. H&E provides longitudinal and transverse resolution within sectioning. Moreover, because different tissues exhibit specific patterns of hematoxylin and eosin binding, pathomorphological features are readily visible. In addition, periodic acid Schiff's (PAS) reagent is exploited to stain the carbohydrates in C. elegans tissues.

Quantification of lipid storage

Oil-Red-O is applicable to whole-mount C. elegans samples for staining neutral fat deposits. The results exhibit as color image segmentation of Oil-Red-O stained and hematoxylin counter-stained are reproducible, and can be quantified to reflect overall lipid content in individual animals. It is reported that morphology and resolution are best preserved in fresh frozen sections that were natively stained with Oil-Red-O, thereby the protocol is applied on our platform.

Monitor metabolic states of various C. elegans tissues

To investigate mitochondrial diseases, oxidative phosphorylation system (OXPHOS) assessment is necessary and the NADH, SDH and COX activities in human muscle biopsies are commonly examined by enzyme histochemistry. Here we offer the direct biochemical detection system in C. elegans fresh frozen sections to complement spectrophotometric methods for enzyme activities and provide an electron transport chain (ETC) enzyme histochemistry protocol to in-depth insight into the mitochondrial function of an individual worm.

C. elegansHistology Service
Items	Services	Characteristics and advantages
C. elegans	Fresh frozen serial sections	1. They retain the original morphology; 2. They also retain the enzymatic activity, antigenicity, lipids and carbohydrates (suitable for biochemical and immunological analyses); 3. Antibodies and histochemicals can easily penetrate cells and tissues.
Morphology of C. elegans	Hematoxylin and eosin (H&E) stained on fresh frozen serial sections	Providing a detailed view of the tissue for routine examination.
Lipid storage of C. elegans	Oil-Red-O stained on fresh frozen serial sections	Avoiding the artifact-prone fixation and permeabilization procedures of traditional whole-mount protocols.
Metabolic states of C. elegans tissues	Enzymatic stains for respiratory chain subunits	Usage of less animals, and permits tissue specific probing with a high level of robustness and accuracy.

Workflow of C. elegans histology service

CD BioSciences works with both academic and corporate investigators worldwide to provide high-quality C. elegans biospecimens to promote relevant research. We now offer C. elegans histological services, including fresh frozen series sections, hematoxylin and eosin (H&E) stained sections, Oil-Red-O staining and enzymatic stains, which refer to morphology, lipid storage of worms and metabolic states of worm tissues histological examinations. With high quality, reproducible results, our services allow you to obtain reliable histology data and accelerate phenotypic analysis of worm model. Furthermore, we provide a basic histology package or our customers can request for customized services. If you are interested in our services, please contact us for more details.

Reference

1. Hench J, et al. (2011). "A tissue-specific approach to the analysis of metabolic changes in Caenorhabditis elegans". PLoS One. 6(12):e28417.

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