Defense chemical

An excellent review by Roth and Eisner (63) summarized the chemical defense substances found in arthropods up to 1962. These authors listed 31 defense substances of known structure one anhydride, three carboxylic acids, nine aldehydes, one furan, three hydrocarbons, two ketones, one lactone, eight quinones, and three inorganic compounds. Many of these same compounds (unsaturated aldehydes and quinones) have been found in other arthropods since 1962 (38). The compounds are discharged when the animal is disturbed by predators, and there can be no doubt that the action of most of them... 

Lasne M-C, Perrio C, Rouden J, Barr L, Roeda D, Dolle F, Crouzel C (2002) Chemistry of b+-Emitting Compounds Based on Fluorine-18.222 201-258 Laughrey ZR, Gibb BC (2005) Macrocycle Synthesis Through Templation. 249 in press Laurent P, Braekman J-C, Daloze D (2005) Insect Chemical Defense. 240 167-229 Lawless LJ, see Zimmermann SC (2001) 217 95-120... 

Pohnert G (2004) Chemical Defense Strategies of Marine. 239 179-219 Ponthieux S, Paulmier C (2000) Selenium-Stabilized Carbanions. 208 113-142 Port M,see Idee J-M (2002) 222 151-171... 

Manninen, A.-M., Vuorinen, M. and Holopainen, J. K. 1998. Variation in growth, chemical defense, and herbivore resistance in Scots pine provenances. J. Chem. Ecol. 24 1315-1331. 

Steinberg, P. D. 1984. Algal chemical defense against herbivores allocation of phenolic compounds in the kelp Alaria marginata. Science 223 405 07. 

Feeding preferences of Tegula funebralis and chemical defenses in marine brown... 

Chemical defenses and the susceptibihty of tropical marine algae to herbivores. 

Machado, G. et al.. Chemical defense in harvestmen (Arachnida, Opiliones) do benzoquinone secretions deter invertebrate and vertebrate predators J. Chem. EcoL, 31, 2519, 2005. 

Keywords Marine chemical defense Activated defense Induced defense Plankton Chemical ecology... 

The ocean is a rich source of natural products, and their structural variety has inspired numerous chemists and chemical ecologists. Comprehensive reviews exist on the structure and occurrence, biosynthesis, and biological activity of marine natural products (see, e.g., [ 1-5]). An excellent book published in 2001 that deals exclusively with marine chemical ecology highlights different aspects of chemical communication and chemical defense [6]. It would be impossible to cover all aspects of chemical defense in this environment, and thus this contribution will focus on a few selected aspects that have been under intense research and discussion in recent years. 

From the large body of literature about chemical defense in the benthic environment (benthos the bottom of the sea and the littoral zones), only a few aspects can be highlighted here. The selection of examples from the benthos will focus on dynamic defense reactions including fast wound-activated and... 

The following sections summarize our sparse knowledge about chemical defense in plankton and outlines the role that defensive metabolites can play in this ecosystem. 

Other roles for noxious metabolites produced by certain phytoplankton species include mediation of allelopathic interactions [47]. Allelopathy covers biochemical interactions among different primary producers or between primary producers and microorganisms. These can provide an advantage for the producer in the competition among different photoautotrophs for resources. Although not directly involved in chemical defense, allelopathic metabolites can affect the dominance and succession of species in phytoplankton therefore they are crucial for understanding plankton composition. In contrast to the fresh water environment, the location of many studies on the role of allelopathic interactions, which have identified active compounds [47], only few studies have addressed this topic in the marine environment. 

One or a few enzymes usually mediate the conversion slight structural changes in the metabolites can markedly enhance potency of chemical defenses... 

In addition to their role in chemical defense, DMSP-lyase products may also function as chemical cue in more complex trophic cascades. In the natural environment DMS-production is related to zooplankton herbivory [60] and can thus act as an indicator for the availability of food for planktivorous birds. Indeed, some Antarctic Procellariiform seabirds can detect DMS (22) and are highly attracted to the cue, as was shown with DMS-scented oil slicks on the ocean surface [61]. The odors released during zooplankton grazing (DMS) as well as those of zooplankton itself (e.g., trimethylamine and pyrazines) are attractive to birds [62], thus assisting vertebrate search behavior. 

Interestingly, the release of PUFAs without subsequent action of a lipoxygenase can act as a wound-activated defense diatom in rich fresh water biofilms. This reaction could be directly associated with a chemical defense against the grazer Thamnocephalus platyurus [78]. 

Only a few studies on defined chemical defense metabolites from non-phyto-plankton organisms that spend their entire life history in the water column have been reported to date [81]. 

One example for a chemically defended zooplankton species is the Antarctic pteropod Clione antarctica. This shell-less pelagic mollusk offers a potentially rich source of nutrients to planktivorous predators. Nonetheless fish do not prey on this organism, due to its efficient chemical defense. In a bioassay-guided structure elucidation, pteroenone 37 could be isolated and characterized as the main defensive principle of C. antarctica [82,83]. If embedded in alginate, this compound is a feeding-deterrent in nanomolar concentrations. This unusual metabolite is likely to be produced by C. antarctica itself and not accumulated from its food, since its major food sources did not contain any detectable quantities of 37. 

In addition to protecting the pteropod, pteroenone 37 can also serve invertebrates as an indirect chemical defense (Fig. 2). The amphipod Hyperiella dilatata gains protection by carrying the pteropod Clione antarctica on its back. That this carrying behavior provides efficient protection is clear, since in all cases... 

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