IB43518 Critical Evaluation of Herbal remedies
Name________________
February 16, 2018 First hour exam
This examination consists of six 25-point questions; answer FOUR of the SIX questions for a total of 100 points. You have
one hour to complete your exam.
1. Sherratt et al. (2005) reported on a study aimed at determining “Why are some mushrooms poisonous, and do they
signal their unprofitability?”
1a. What can you conclude about the association between unpleasant smells and toxicity in North American and
European mushrooms?
1b. What is olfactory aposematism?
1c. Why might this form of aposematism occur in mushrooms as opposed to aposematism based on visual cues?
1d. What statistical test (bottom box) was used to analyze the data?
1e. Why is this test appropriate?
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2a. Amphinomids, or fireworms, are marine annelids that possess calcareous ( calcium carbonate-containing) spines
that break off when another organism brushes against them, leaving a sharp edge. People who brush against fireworms
can experience inflammation, burning pain (hence the name “fireworm”), numbness, and even nausea. Verdes et al.
(2018) recently reported that, in at least three species, the spines are capable of injecting a complex mixture of toxins,
including lectins, peptidases, metalloproteinases, potassium channel-blocking toxins, and CAP (cysteine-rich secretory,
antigen-5, and pathogenesis-related ) proteins.
How is the delivery system of fireworm venom different from the venom delivery system of cone snails?
2b. Are all venom constituents toxic? If not, what other functions might they serve?
2c. Fireworms are slow swimmers that hide under rocks during the day, venturing out to feed on corals at night. They
can be difficult to find because they can change their color to match their background. By contrast, many nereid
polychaetes, called ragworms, are active predators, swimming in all water depths to capture their prey. Some species of
ragworms are popular to feed fish in aquaculture or as bait for marine fishing. Can you offer an ecological explanation
for the differential toxicity of fireworms and ragworms?
2d. Ziconotide is an analgesic (pain-killer) derived from a cone snail. Why would one marine organism produce a painkiller while another marine organism produces pain-inducing compounds? Compare the aspects of the biology of cone
snails and fireworms that might explain the different strategies.
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2e. Chemical defenses in marine systems are similar in some ways to chemical defenses in terrestrial system and in
some cases the same toxin can be found in both types of environments. Name a toxin that appears in both a marine
organism and a terrestrial organism.
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2. Tansy ragwort (Jacobaea vulgaris, formerly Senecio jacobaea) is also known as stinking willie; it’s an introduced
weed in the western USA, where it can kill cattle when it is eaten. The toxic agents are pyrrolizidine alkaloids that cause
hepatotoxicity (or liver toxicity).
a. What is an alkaloid?
b. Pyrrlolizidine alkaloids are plant secondary metabolites; what would you predict about its distribution and occurrence
across the plant kingdom?
c. The cinnabar moth, Tyria jacobaeae, was introduced from Europe to control tansy ragwort; as a caterpillar, it is
unaffected by the alkaloids and feeds almost exclusively on tansy ragwort, greatly reducing its numbers. The larvae
sequester the alkaloids and are themselves toxic to predators (and have few enemies in North America). What features
of insect biology are conducive to sequestering plant compounds?
d. Name another insect that consumes a toxic plant and sequesters plant secondary metabolites for its own defense.
e. Some plant alkaloids act on animal nervous systems. Name a plant alkaloid that targets the nervous system and the
plant that produces it.
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4. Yi et al. (2004) carried out a clinical trial to determine the effect of the Chinese traditional medicine Cordyceps sinensis “in
enhancing aerobic capacity and respiratory function of the healthy elderly volunteers” (Chinese Journal of Integrative Medicine 10:
187-192).
4a. The clinical trial was randomized, double-blind and placebo-controlled. What do these terms mean?
1. randomized
2. double-blind
3. placebo-controlled
4b. The methods for this study were described as follows: “Thirty-seven healthy, elderly Chinese subjects were randomly assigned
to receive either Cs-4 (3 g/ day) or identical placebo capsules. Their exercise performance was tested before and after 6 weeks of
treatment with a symptom-limited, incremental work rate protocol on a cycle ergometer. Maximum oxygen uptake (VO 2max) was
measured using a metabolic chart. Anaerobic thresholds (VO2θ) were identified by two observers using plots of both VCO 2 vs VO2
and VE/VO2 vs time.” Patients took Cordyceps sinensis for six weeks; 7 subjects dropped out of the trial before it ended for a
variety of reasons. Researchers found that at the end of the trial maximum oxygen uptake and anaerobic thresholds were
significantly increased compared with the placebo treatment arm.
VO2max went from 1.88±0.13 to 2.00±0.14 L／min; p = 0.05. What is a p value and how do you interpret a p value of 0.05?
4c. These authors carried out a power analysis “for the percentage change of the maximal work load under the study protocol”;
what’s a power analysis and why do you think these investigators carried out such an analysis?
4d. What is cordycepin? What are its putative medicinal properties?
4e. Name three types of mushroom toxins.
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