Chemical Ecology The Chemistry of Biotic Interaction (1995) / Chapter Skim
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The Chemistry of Phyletic Dominance
The Chemistry of Phyletic Dominance
Pages 29-40
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From page 29... ...
, which enabled insects to effect direct sperm transfer from male to female, without recourse to an outer aquatic environment for fertilization (31. Jerrold Meinwald is Goldwin Smith Professor of Chemistry and Thomas Eisner is Schurman Professor of Biology and director of the Cornell Institute for Research in Chemical Ecology at Cornell University, Ithaca, New York.
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From page 30... ...
ARTHROPOD CHEMICAL DEFENSES In our earliest collaborative publication, we described the dramatic chemical defense mechanism of the whip scorpion, Mastigoproctus giganteus (61. This ancient arachnid is able to spray a well-aimed stream of ~85% acetic acid ECH3CO2H:I containing 5% caprylic acid ECH3(CH2~6CO2H]
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From page 33... ...
readily available for biological investigation for the first time. How the insects themselves manage to obtain their defensive pregnanes and steroidal pyrones remains a mystery, since insects are generally considered to lack the enzymatic machinery essential for steroid biosynthesis (191.
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From page 34... ...
, the azaacenaphthylene skeleton of B is known, again combined with fragment A, only from the recently described hexacyclic alkaloid exochomine (251. Since pyrroles are not basic, we would expect tricyclic compounds resembling B to have been missed in a conventional alkaloid isolation scheme, and we anticipate that a targeted search for these novel pyrroles may well turn up additional examples of this otherwise unknown ring system.
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From page 35... ...
Interestingly, the pupa of this beetle, which is densely covered with glandular hairs, secretes an entirely different group of defensive alkaloids, the azamacrolides, which function as highly effective ant repellents (Figure 21. We have described these unique macrocyclic compounds, of which the most important example is epilachnene, in a recent "advertisement" (27~.
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From page 36... ...
SPIDER VENOMS In addition to their widespread exploitation of organic compounds for defensive purposes, arthropod species often use offensive chemical weaponry. Many spiders possess venoms capable of paralyzing their prey, and consequently spider venoms have become a popular hunting ground for neurotoxins of potential neurochemical and neurotherapeutic utility (29~.
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From page 37... ...
Because of the very limited supply of this material, and because a family of compounds closely related to the natural product should prove useful in studying structure-activity relationships, we set out to synthesize a set of candidate guanosine fucopyranosides of clearly defined structure and stereochemistry. This synthetic effort has enabled us to characterize HF-7 itself by direct comparison of the natural product with several unambiguously constructed reference compounds (351.
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From page 38... ...
From these alone, it is evident that insects synthesize defensive compounds by using all of the major biosynthetic pathways, producing acetogenins, simple aromatics and quinones, isoprenoids, and alkaloids. In addition, some of the millipedes, coccinellid beetles, and spiders we have studied utilize biosynthetic pathways that have yet to be characterized.
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From page 39... ...
The newly emerged larvae on leR have not as yet accumulated sufficient dietary oil for defense. [Bars = 0.5 cm (amp 1 cm (gaff)
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From page 40... ...
The venom of a fishing spider, Dolomedes okefinokensis, has yielded a polyamine which reversibly blocks L- and R-type voltage-sensitive calcium channels. Most recently, we have characterized, from the funnel-web spider Hololena curia, a sulfated nucleoside glycoside which serves as a reversible blocker of glutamate-sensitive calcium channels.
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