Leaf disk assay

The ozone treatment had no significant effect on the vitro NR activity, indicating that it did not inactivate the NR protein (Table III), Leaf extracts that would couple the oxidation of fructose-1, 6-diphosphate to nitrate reduction were prepared from leaves exposed to either 0 or 980 yg/m ozone ( ), Ozone depressed the in vitro coupled NR activity 58% (Table III), indicating that the observed ozone depression of nitrate reduction in the vivo leaf disk assay resulted from a depression in the rate of NADH formation by GPD,... 

In fact, abyssinol A (II), B (III) and C (IV), isolated monitoring by the leaf disk assay> did not show any Insect growth inhibitory activity, as is shown in Table III. 

We will perform the Leaf disk test, also known as leaf disk assay or leaf disk choice test, the second of two bioassays of tannins in the diet of insects in this book. In this often used bioassay, leaf sections of a standard size are treated with the compound(s) in question. Several circular leaf sections ( leaf disks ) (Ali et al. 1999, Filho and Mazzafera 2000, Shields et al. 2008, Wheeler and Isman 2000) or cellulose membrane filters (Hollister and Mullin 1999, Larocque et al. 1999) are presented to a caterpillar in a choice experiment. We measure how much chow the caterpillar has consumed and whether any feeding inhibition is concentration dependent. Regardless of what compounds are being tested, leaf disk tests serve as an important tool in bioassaying feeding inhibitors and stimulants in insects. The cited references are examples of such studies. (In the first tannic acid experiment - Chap. 18 - the tannic acid was mixed into diet in varying concentrations.)... 

There are two types of receptor, termed fast and slow sites [21]. The fast responses (detectable in <5 min) appear to be brought about by membrane-mediated phenomena, while the slow responses, which involve protein synthesis, are not detectable within the first half hour. The receptor types have different molecular requirements, and the fast reaction is not a pre-requisite for the slow. Growth assays employed to assess activity include Avena coleoptile, lettuce hypocotyl, rice seedling, and bean axis. Other types include lettuce seed and wheat embryo germination, transpiration assays, leaf disk senescence, and more recently, a-amylase production. Stomatal closing using epidermal strips is an assay for the fast receptor. 

Our first attempt was to synthesis some libraries, where we replaced the Z-double bonds with benzene rings, and the complex side chain with simpler groups. Typical examples were Compounds 8 and 9, (Figure 3). All the compounds were tested on a cascade consisting of the beef heart mitochondrial respiration assay and application to fimgi on leaf disks, with the most active compounds then being tested on fimgi on small plants. Unfortunately, none of the compounds showed activity in any of these tests. 

Jones, C.G. J.S. Coleman. 1988. Leaf disk size and insect feeding preference implications for assays and studies on induction of plant defense. Entomol. Exp. Appl. 47 167-172. 

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