C. elegans Cultivation

Summary: to study the worm, we first have to make it happy in the laboratory setting. Issues like how it grows and what it eats need to be taken into account.

Life Cycle of the worm

The life cycle of the worm is about 3 days.


Life cycle of the worm

Feeding the worm

In the lab, Escherichia coli (E. coli) OP50 (strain nameG) is its favorite food.


(Click to see a worm eating)

Housing the worm

Petri plate (~ 35 * 10 mm) filled with NGM (Nematode Growth Medium) is used to culture the worm.

Click on the image to view its bigger image.

Covered petri dish with NGM and a lawn of E. coli in the center.

Same as the left hand side one with lid on its left.

Same as the previous two with its lid half covered.

Growing temperature for the worm

C. elegans‘ growth rate differs under different temperatures. Development from embryo to adult takes about 2.5 days at 25 °C , and 6 days at 15 °C.

Temperature
(°C)
EmbryogenesisG
(hours)
MoltsG (hours after hatch)
First eggs laid (hours after hatch)
Larva1 (L1)G-L2
L2-L3
L3-L4
L4-adult
16
29
24
39
54.5
74.5
94-97
20
18
15
24
34
46
59-60
25
14
11.5
18.5
26
35.5
45-46
Source: Caenorhabditis elegans: Modern Biological Analysis of an Organism (p.9)

Observing the worm

A binocular dissecting microscope will do. Most work can be done at 25X magnification.


(A dissecting microscope, click to view bigger image)

Picking & transferring the worm

To pick and transfer worm for manipulation, a platinum wire is used.


(A platinum wire with glass handle, click to view bigger image)

Sexing the worm

Size of plate (with food)
Number of males
Number of hermaphroditesG
9 cm
10 -15
~ 6
5 cm
~ 6
3-4
Source: Caenorhabditis elegans: Modern Biological Analysis of an Organism (p.12)

 

Long term storage of the worm

C. elegans can be stored indefinitely at very low temperature (-70 ~ 100 °C freezer). In the dauerG larval stage, it can also be kept at 16 °C for months.

Credits:

1. A Worm Eating: The Ward lab, Retrieved 12/10/04, From http://www.mcb.arizona.edu/wardlab/eatingvid.html.

Reference

Epstein, F. H. & Shakes, C. D. (Ed). (1995). Caenorhabditis elegans: Modern Biological Analysis of an Organism. New York, NY: Academic Press.

Glossary:

Dauer: a developmental stage of C. elegans that occurs under starvation conditions in which the larva enters developmental stasis. With food, the dauer larva can reach L4 stage and then become an adult.

Embryogenesis: early developmental process of an individual from a fertilized egg (zygote) to hatching.

Hermaphrodite: hermaphrodite is the form that can make both sperm and oocytes and can self-fertilize. C. elegans has both hermaphrodites and males. The male can mate with hermaphrodites to produce cross progeny.

Larva: The immature forms of C. elegans. After hatching, C. elegans undergo a series of larval stage, called L1 – L4, before becoming adults.

Molt: the process of growing a new cuticle and shedding the old one. This defines the transition from one larval stage to another or to adulthood.

Strain: a pure breeding lineage.