Traditionally, plant defenses have been divided into two main categories: chemical and mechanical defenses. The first category includes a variety of substances that are toxic, repellent, or that render plant tissues indigestible to animals. In the second category are a series of physical barriers to avoid being eaten. These include structures such as spines, trichomes, and hard, very sticky, or smooth surfaces. Studies dealing with either one of these two kinds of defenses typically assume they are independent of each other and that their actions on herbivores are additive (Dussourd and Denno, 1991; Farrell et al. , 1991; Becerra, 1994 b ). Yet, in some plants, structures such as glandular trichomes and secretory canals are combinations of mechanical and chemical deterrence that may interact to entrap insects in sticky and toxic secretions (Southwood, 1986; Howe and Westley, 1988; Becerra, 1994 a ). In this article we report an investigation of plant secretory canals and their relationship with plant chemistry in the genus Bursera . We present data suggesting an interaction between the mechanical and the chemical components of this defense. Also we present data which suggest that the interaction between these components has profound repercussions on how Bursera 's herbivores defend themselves against their predators. Many species of plants produce secretions such as resins, latices, gums, and mucilages stored under pressure in networks of canals throughout the cortex of the stems and in the leaves, where they follow the vascular bundles (Fahn, 1979; Metcalfe and Chalk, 1983). Latex and resin canals occur in more than 35,000 species (Farrell et al. , 1991). When such plants are damaged, there is an immediate release of fluids from injured tissues, often in copious quantities. In many species, canals transport antiherbivore repellents and toxins. For example, canals in some Apiaceae store …

Traditionally, plant defenses have been divided into two main categories: chemical and mechanical defenses. The first category includes a variety of substances that are toxic, repellent, or that render plant tissues indigestible to animals. In the second category are a series of physical barriers to avoid being eaten. These include structures such as spines, trichomes, and hard, very sticky, or smooth surfaces. Studies dealing with either one of these two kinds of defenses typically assume they are independent of each other and that their actions on herbivores are additive (Dussourd and Denno, 1991; Farrell et al. , 1991; Becerra, 1994 b ). Yet, in some plants, structures such as glandular trichomes and secretory canals are combinations of mechanical and chemical deterrence that may interact to entrap insects in sticky and toxic secretions (Southwood, 1986; Howe and Westley, 1988; Becerra, 1994 a ). In this article we report an investigation of plant secretory canals and their relationship with plant chemistry in the genus Bursera . We present data suggesting an interaction between the mechanical and the chemical components of this defense. Also we present data which suggest that the interaction between these components has profound repercussions on how Bursera 's herbivores defend themselves against their predators. Many species of plants produce secretions such as resins, latices, gums, and mucilages stored under pressure in networks of canals throughout the cortex of the stems and in the leaves, where they follow the vascular bundles (Fahn, 1979; Metcalfe and Chalk, 1983). Latex and resin canals occur in more than 35,000 species (Farrell et al. , 1991). When such plants are damaged, there is an immediate release of fluids from injured tissues, often in copious quantities. In many species, canals transport antiherbivore repellents and toxins. For example, canals in some Apiaceae store …

Plumbagin (5-hydroxy-2-methyl-1,4-naphthoquinone) (CAS Reg. No. 481-42-5) was isolated from the bark of Diospyros olen (Ebenaceae) via an antibiotic guided biological assay using the bacterium Pseudomonas solanacearum. D. olen bark, collected in New Caledonia, was extracted with dichloromethane and components separated by flash chromatography on silica.[...]

A cDNA encoding a cytochrome P450 enzyme was isolated from a cDNA library of the corpora allata (CA) from reproductively active Diploptera punctata cockroaches. This P450 from the endocrine glands that produce the insect juvenile hormone (JH) is most closely related to P450 proteins of family 4 and was named CYP4C7, The CYP4C7 gene is expressed selectively in the CA; its message could not be detected in the fat body, corpora cardiaca, or brain, but trace levels of expression were found in the midgut and caeca, The levels of CYP4C7 mRNA in the CA, measured by ribonuclease protection assays, were linked to the activity cycle of the glands. In adult females, CYP4C7 expression increased immediately after the peak of JH synthesis, reaching a maximum on day 7, just before oviposition, mRNA levels then declined after oviposition and during pregnancy. The CYP4C7 protein was produced in Escherichia coli as a C-terminal His-tagged recombinant protein. In a reconstituted system with insect NADPH cytochrome P450 reductase, cytochrome b(5), and NADPH, the purified CYP4C7 metabolized (2E,6E)-farnesol to a more polar product that was identified by GC-MS and by NMR as (10E)-12-hydroxyfarnesol. CYP4C7 converted JH III to 12-trans-hydroxy JH III and metabolized other JH-like sesquiterpenoids as well. This omega-hydroxylation of sesquiterpenoids appears to be a metabolic pathway in the corpora allata that may play a role in the suppression of JH biosynthesis at the end of the gonotrophic cycle.

Turkey has an extraordinarily rich flora and wide knowledge of their indigenous medicinal plants. Medicinal plants constitute an important component of flora and are widely distributed in different floristic regions of Turkey. Historically, plants have supplied the chemistry for over 25 % of prescription drugs used in human medicine(l) and such biologically active plants have also provided leads to natural insecticides(2). Accordingly, we are investigating the potential, of Turkish medicinal plants as a resource of new chemistry for public health and plant protection. The biological evaluation of substances from plant sources is highly releavant for the identification of lead compounds which can result in the development of novel and safe medicinal agents. During our extensive studies with Turkish medicinal plants, we have isolated and characterized a large number of natural products. On the other hand, a more systematical approach to the discovery of drugs from these plants has been initiated using bioassay-guided fractionation. At the end of this fractionation of selected plant extracts has resulted in the identification of active compounds representing a wide range of structures, including alkaloids, terpenoids and phenolic compounds(3). Fifty five organosoluble extracts prepared from Turkish medicinal plants were investigated for their biological activities against insects, nematodes, plant pathogens and brine shrimp in addition to their biological activities such as antimalarial, anticholinergic, analgesic and antiplatelet activities.

Page 342 of the above article in Volume 16 (1995) was inadvertently omitted during printing. Its full text is given below.

Heterologous expression in Escherichia coli, purification, and reconstitution of house fly P450 6A1 and NADPH-cytochrome P450 reductase were used to study the metabolism of terpenoids. In addition to the epoxidation of cyclodiene insecticides demonstrated previously [Andersen et al. (1994) Biochemistry 33, 2171-2177], this cytochrome P450 was shown to epoxidize a variety of terpenoids such as farnesyl, geranyl, and neryl methyl esters, juvenile hormones I and III, and farnesal but not farnesol or farnesoic acid. P450 6A1 reconstituted with NADPH-cytochrome P450 reductase and phosphatidylcholine did not metabolize alpha-pinene, limonene, of the insect growth regulators hydroprene and methoprene. The four geometric isomers of methyl farnesoate were metabolized predominantly to the 10,11-epoxides, but also the 6,7-epoxides and to the diepoxides. The 10,11-epoxide of methyl (2E,6E)-farnesoate was produced in a 3:1 ratio of the (10S) and (10R) enantiomers. Monoepoxides of methyl farnesoate were metabolized efficiently to the diepoxides. Methyl farnesoate epoxidation was strongly inhibited by a bulky substituted imidazole. The active site topology of P450 6A1 was studied by the reaction of the enzyme with phenyldiazene to form a phenyl-iron complex. Ferricyanide-induced in situ migration of the phenyl group showed formation of the N-phenylprotopor-phyrinporphyrin IX adducts in a 17:25:33:24 ratio of the NB:NA:NC:ND isomers. These experiments suggest that metabolism of xenobiotics by this P450, constitutively overexpressed in insecticide-resistant strains of the house fly, is not severely limited by stereochemically constrained access to the active site.

The insect anti-juvenile hormones precocene I and II (7-methoxy-2,2-dimethyl-2H-1-benzopyran and 6,7-dimethoxy-2,2-dimethyl-2H-1-benzopyran) were identified in three of nineNama (Hydrophyllaceae) species. Precocene I occurred inN. lobbii while precocene II occurred inN. hispidum, N. lobbii andN. sandwicense. N. hispidum contained the highest concentration (ca 0.5% dry weight) of precocene II, which was found in the leaves, stems, seed capsules, corolla, glandular trichomes, and seeds. In addition to the anti-juvenile hormone, insect juvenile hormone activity was detected in the organosoluble extracts ofN. rothrockii andN. sandwicense. N. sandwicense is the first plant discovered to contain compounds with both anti- and juvenile hormone activity.

ADVERTISEMENT RETURN TO ISSUEPREVArticleSynthetic optimization of laetisaric acid for fungicidal activityWilliam S. Bowers, Philip H. Evans, and Masato KatayamaCite this: J. Agric. Food Chem. 1987, 35, 6, 1043–1046Publication Date (Print):November 1, 1987Publication History Published online1 May 2002Published inissue 1 November 1987https://doi.org/10.1021/jf00078a044RIGHTS & PERMISSIONSArticle Views70Altmetric-Citations3LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (464 KB) Get e-Alerts Get e-Alerts

Laetisaria arvalis , a soil-dwelling basidiomycete fungus, secretes an allelopathic agent that induces rapid hyphal lysis in several phytopathogenic fungi. The active compound was isolated from chloroform:methanol extracts of L. arvalis mycelia and characterized as a previously unknown hydroxy fatty acid, ( Z , Z )-9,12-8-hydroxyoctadecadienoic acid.

A compound with significant insect juvenile hormone activity was isolated from the plant, Macropiper excelsum . The chemical structure was determined by spectral methods to be 1-(3,4-methylenedioxyphenyl)-trans-3-decene(l), and confirmed by synthesis. The hormonally active substance applied topically to last (fifth)-instar nymphs of the milkweed bug ( Oncopeltus fasciatus ) induced a supernumerary metamorphosis at 30 μg. Higher doses were toxic.

Cytotoxic agents with antijuvenile hormone activity in insects have been discovered. Their mechanism of action may involve an oxidative bioactivation into a reactive quinone methide.

The elemental analyses whose basis is described in the preceding two papers represent the composition of samples of Martian fines; the only undetermined major constituents thought to be present are H2O, CO2, Na2O, and possibly NOx. The samples are principally silicate particles, with some admixture of oxide and probably carbonate minerals; the fines appear to have been indurated to a variable degree by a sulfate-rich intergranular cement. The overall elemental composition is dissimilar to any single known mineral or rock type and apparently represents a mixture of materials. Close chemical similarity among samples at each site, and between the two sites, indicates effective homogenization of the fines, presumably by planetary windstorms, and further suggests that the samples analyzed represent the fine, mobilizable materials over a large part of the planet's surface. Low trace element, alkali, and alumina contents suggest that the great preponderance of the materials in the mixture is of mafic derivation; highly differentiated, salic igneous rocks or their weathering products are insignificant components of the samples. Normative calculations, comparisons with reference libraries of analytical data, and mathematical mixture modeling have led to a qualitative mineralogical model in which the fines consist largely of iron-rich smectites (or their degradation products), carbonates, iron oxides, probably in part maghemite, and sulfate minerals concentrated in a surface duricrust. The original smectites may have formed by interaction of mafic magma and subsurface ice, and the sulfates (and carbonates?) may have been concentrated in the surface crust by subsurface leaching, upward transport, and evaporation of intergranular moisture films. Testing and refinement of this and competing models will accompany continuing acquisition of samples and data and refinement of the analyses, particularly with respect to the critical light elements Mg, Al, and Si.

Elemental analyses of fines in the Martian regolith at two widely separated landing sites, Chryse Planitia and Utopia Planitia, produced remarkably similar results. At both sites, the uppermost regolith contains abundant Si and Fe, with significant concentrations of Mg, Al, S, Ca, and Ti. The S concentration is one to two orders of magnitude higher, and K(<0.25 percent by weight) is at least 5 times lower than the average for the earth's crust. The trace elements Sr, Y, and possibly Zr, have been detected at concentrations near or below 100 parts per million. Pebblesized fragments sampled at Chryse contain more S than the bulk fines, and are thought to be pieces of a sulfate-cemented duricrust.

Hollywood, California *P. H. EVANS, M.D. is on the staff of the Hollywood Presbyterian Hospital. He received the degrees of B.S. and M.D. from the University of Tennessee and served a residency at Los Angeles County General Hospital. He was a Flight Surgeon and Director Physiological Training Units during periods of military duty 1947 to 1949 and 1950 to 1952. Dr. Evans is Secretary-Treasurer of the medical staff for 1960 of Hollywood Presbyterian Hospital. He is the author of Aviation Physiology, a manual of instruction for Directorate of Flight Safety Research under contract With the University of Southern California, 1953. Dr. Evans' hobby is skiing, and he and his wife, Marie, are the parents of a son—Alexander. *CHARLES GEORGE HUTTER, M.D., an orthopedic surgeon, is Chief of Surgery at Hollywood Presbyterian Hospital and Consultant on Prosthetics to the Veterans Administration. He received the B.S. degree from Harvard College and his M.D. degree from Harvard University. Dr. Hutter was a Captain in the U.S. Army, attached to O.S.S. and several general hospitals during three years of military service. His special interests are skiing, hiking and photography. Dr. and Mrs. Hutter are the parents of two sons.