05 - Heavy Metal: Effects of Environmental Toxins on C. elegans
time, male fecundity, and susceptibility to multiple DNA alteration techniques have allowed scientists to create thousands of different mutational strains in this species. In environmental toxicology, different strains are used to better understand how an individual’s genetics and its environment interact to determine the biological consequences of toxic exposure. In addition, mutant strains that are more susceptible to toxicants enable toxicologists to run faster and more sensitive bioassays. In this experiment you will be using a strain with a loss of function mutation in the adr-2 gene that makes individuals more vulnerable to environmental pollution.
Adult (1110-1150 µm) (capable of egg laying)
Young Adult (900-940 µm)
8 hr.
ex utero development (9 hours)
Egg Hatching
10 hr.
molt
L4 (620-650 µm)
L1 (250 µm)
molt
up to 4 months
8 hr.
13 hr. Predauer (L2d)
12 hr.
Dauer (400 µm)
molt
L3 (490-510 µm)
molt
L2 (360-380 µm)
molt
8 hr.
Figure 3: Life Cycle of C. elegans
Heavy Metal Pollution and Human Health Heavy metals are a loosely defined group of high-density chemical elements (Figure 4). While naturally occurring, many of these elements have become concentrated in certain areas as a result of mining, industrial waste, agricultural runoff, and use in products like paint and treated wood. Heavy metals also tend to bioaccumulate in living organism because they are often stored in fat tissue rather than metabolized. Some heavy metals such as iron, zinc, copper,
cobalt, and manganese
play crucial bio- logical roles in processes like oxygen deliv- ery, free radical removal, and cell signaling. However, these
Cr
Co Ni Cu Zn
As Se
Sb
Ag Cd
Hg Tl Pb
Figure 4: Examples of Toxic Heavy Metals.
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