Despite C. elegans being an attractive model system and widely used for many fundamental biological studies, the biology of C. elegans is another important key point to starting research with. Previously, insights into C. elegans biology were exclusively established with the analysis of a single reference strain (N2). Nowadays, research has begun to investigate genetic and phenotypic variation based on C. elegans wild isolates. Studies have demonstrated that the reference strain N2 exhibits laboratory adaptation extensively, while the natural populations of C. elegans show very little genetic differentiation worldwide. However, some of the marked phenotypic differences between C. elegans natural variation have been genetically and molecularly identified through quantitative genetic mapping approaches. Generally, the characterization of the nematode wild isolates elucidates C. elegans biology from a novel perspective. Herein, we provide the service for sampling and isolation of C. elegans wild isolates, primarily aimed to offer convenience for researchers using C. elegans as a study organism and promote the wealth of mechanistic knowledge of C. elegans biology accumulation for the further research of a much-needed ecological and evolutionary context.
Although C. elegans is commonly referred to as a soil nematode, the worm has been widely isolated from various organic substrates above the soil layer, instead of soil samples. The decaying vegetal matter belongs to organic substrates including fruits, plant stems, and compost. Moreover, the nematode can also be isolated from a range of invertebrates, such as millipedes, isopods, and slugs. C. elegans isolates distribute worldwide, the characteristics of the distribution are correlated with temperature, and the species in temperate regions are more abundant than the tropical regions. Few C. elegans isolates are found in the tropics and mostly at high altitudes. Consistent with experimental data measured in the lab, the thermal optima of C. elegans is 25 °C and can't tolerate prolonged exposure above this temperature. Furthermore, it is notable that because of strong sampling bias, the current study of the global distribution of C. elegans is largely limited. There are beyond anthropogenic habitats, the more unperturbed sites such as forests for in-depth sampling and isolation of C. elegans isolates.
Geographic distribution of C. elegans wild isolates. (Poullet N, et al, 2015)
The substrate samples are handled with large NGM plates seeded with a spot of E. coli OP50. In order to avoid worms spreading and cross- contamination among plates, the parafilm is adopted to wrap plates. And the samples are kept at 15-20 °C for 5-7days. To observe the growth of the nematodes, a standard dissecting stereomicroscope equipped with a transmitted light source is applied. Once the growth of various bacteria and fungi on the plate makes the observation difficult over time, the issue can be dealt with by cutting out a piece of agar containing nematodes and transferring to a new plate for further visual observation. Finally, an individual nematode is picked to fresh plates and the population is amplified.
- Identify from morphological and molecular level
The protocol allows for rapid and easy identification of C. elegans, involving examination of typical Caenorhabditis species morphology (the characteristic for Caenorhabditis includes long and pointy tail, central vulva, oval embryos and among others) using a dissecting scope, the selection of hermaphrodites, species specific DNA sequence-tag analytical approach (Caenorhabditis ITS2 sequences).
Morphological characteristics of the C. elegans pharynx compared to a selection of other nematode taxa. (Poullet N, et al, 2015)
- Genetic identification through crosses with established C. elegans strains
C. elegans do not produce any cross progeny with any other known Caenorhabditis species. Therefore, we offer a complement or alternative approach to verify a new isolate of C. elegans species identity through crosses with known C. elegans strains, such as the reference strain, N2. The result shows a high proportion of males (>30 %) in the F1 progeny, indicating successful crossing and confirming C. elegans species identity.
A new C. elegans isolate is amplified resulting in populations over 4–5 generations, thus the isolates can be considered nearly isogenic.
CD BioSciences is a professional C. elegans model service provider. Here, we offer isolate and identify C. elegans from their natural habitat to meet customers' needs for novel insights into C. elegans biology. We provide a one-stop solution of high-quality. If you have needs in this area, please contact us for more details.
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