Attachment ability of the beetle Chrysolina fastuosa on various plant surfaces

To study the role of different structures of a plant surface preventing insect attachment, a variety of plant surfaces were screened. Attachment ability of the beetle Chrysolina fastuosa Scop. (Coleoptera, Chrysomelidae) was measured on 99 surfaces among them smooth, hairy, felt-like, waxy, and glandular ones of three plant organs (stems, leaves, fruits) of 83 plant species belonging to 45 families. Insects attached successfully to smooth, hairy, and felt-like substrata. These surface types did not effect the further attachment of C. fastuosa, indicating the adhesive system remained intact after contacting these substrata. However, the beetles could not attach properly to surfaces covered with wax crystalloids or glandular hairs. In most experiments on pruinose plant substrata, no influence of the surfaces on the subsequent attachment ability of insects was observed. Only in one case (the stem of Acer negundo), was such an impairment recorded, but recovery of attachment ability was fast. Crystalloids of this plant species probably temporarily disable function of tenent setae of C. fastuosa. Four hypotheses, explaining anti-adhesive properties of plant surfaces, covered with wax crystalloids are proposed. A plant surface with glandular trichomes disabled the attachment system of the beetle for a long time. Secretions of trichomes probably glue tenent setae together making further attachment impossible.     

Ultrastructure of the glandular epidermis on the fins of male estuarine triplefins Forsterygion nigripenne

Male estuarine triplefins Forsterygion nigripenne develop enlarged fin tips during the breeding season. Using light microscopy and scanning and transmission electron microscopy the fins of males and females were compared. Tall columnar cells proliferated in the fin epidermis of males but were absent in females. The columnar cells were packed with proteinaceous granules that were bound by a double membrane. Three stages of development of columnar cells could be distinguished; the most mature expanded and ruptured to release its content. The function of the glandular epidermis is unknown but behavioural observations suggested that the secretion was applied to the egg mass and thus may protect it from infection.     

Lipophilic Phenolics from the Leaves of Empetrum nigrum — Chemical Structures and Exudate Localization

In the course of continuing studies on the occurrence and chemical composition of lipophilic exudates on plant surfaces, the leaves of Empetrum nigrum have been studied. They were found to produce a considerable amount of lipophilic material which mostly consists of phenolic compounds. We here report the identification of two dioxygenated chalcones, three dioxygenated dihydrochalcones, and two dihydrophenanthrene derivatives. Exept for one chalcone, all these compounds were found for the first time as natural products. The upper and lower epidermis of the rolled hypostomatous leaves bear glandular trichomes. By flavonoid specific staining it can be shown that these natural products are accumulated within the capitate glandular cells.     

The expression of Lewisx on carcinoembryonic antigen (CEA)-related glycoproteins of normal and inflamed oesophageal squamous mucosa

Carcinoembryonic antigen (CEA)-related antigens were detected histologically in normal and inflamed oesophageal squamous mucosa using polyclonal anti-CEA antisera and monoclonal antibodies recognizing CEA or NCAs (non-specific cross-reacting antigens). Expression was limited to the surface of more mature squames. Immunoblotting of detergent extracts of oesophageal mucosa separated on polyacrylamide gels using polyclonal anti-CEA antisera showed a number of CEA-related proteins, of 195, 145, and 80 kDa. CEA-specific monoclonal antibodies recognized only the 195-kDa glycoprotein. The lower molecular weight species were recognized by anti-NCA antibody DD9 and a CD66 antibody. The carboyhydrate antigen Lewis^x (Le^x, CD15), previously shown to be a marker of mature squames, was present predominantly on a subpopulation of the 195-kDa antigen and was demonstrable on the higher molecular weight component of a doublet recognized by the CEA antibodies. Expression of Le^x carbohydrate antigens in inflamed oesophageal squamous mucosa was shown to be significantly reduced relative to the expression seen in normal tissue. A suprabasal layer of CEA-positive, Le^x-negative cells became apparent in inflamed tissue showing altered glycosylation of the CEA under these conditions. It is postulated that CEA plays a role in maintaining the integrity of the squamous mucosa.     

LacZ expression in Fut2-LacZ reporter mice reveals estrogen-regulated endocervical glandular expression during estrous cycle, hormone replacement, and pregnancy

The secretor gene (FUT2) encodes an alpha(1,2)fucosyltransferase (E.C. 2.4.1.69) that elaborates alpha(1,2)fucose residues on mucosal epithelium and secreted mucins. Though uterine alpha(1,2)fucosylated glycans have been proposed to be involved in embryo adhesion, mice with a homozygous null mutation of Fut2 displayed normal fertility. To help develop alternative hypotheses for function, the cell type and regulation of Fut2 expression during the estrous cycle, hormone replacement, and pregnancy was examined in Fut2-LacZ reporter mice containing targeted replacement of Fut2 with bacterial lacZ. LacZ expression in the reproductive tract of Fut2-LacZ mice is most prominent in the glandular epithelium of the endocervix during estrus and pregnancy. Nuclear LacZ expression identifies cell-specific expression of Fut2 in mucus-secreting cells of the endocervix, uterine glands, foveolar pit and chief cells of the stomach, and goblet cells of the colon. In ovariectomized Fut2-LacZ mice, estradiol treatment stimulates X-gal staining in endocervix and uterus but does not affect expression in stomach and colon. Northern blot analysis in wild-type mice shows 15-fold elevations of Fut2 steady-state mRNA with estradiol treatment, whereas Fut1 varies little. Fut2 levels in the glandular stomach and distal colon remain constant, and uterine Fut2 levels vary eightfold during the estrous cycle. These data represent the first demonstration of a glycosyltransferase gene under tissue-specific hormonal regulation in a LacZ reporter mouse model. Endocervical expression of Fut2 in estrus and pregnancy may modify cervical mucus barrier properties from microbial infection analogous to the potential role of mucosal glycans in humans.     

Structure of the receptacular nectary and circadian metabolism of starch in the ant‐guarded plant Ipomoea cairica (Convolvulaceae)

Nectaries occur widely in Convolvulaceae. These structures remain little studied despite their possible importance in plant–animal interactions. In this paper, we sought to describe the structure and ultrastructure of the receptacular nectaries (RNs) of Ipomoea cairica, together with the dynamics of nectar secretion. Samples of floral buds, flowers at anthesis and immature fruits were collected, fixed and processed using routine methods for light, scanning and transmission electron microscopy. Circadian starch dynamics were determined through starch measurements on nectary sections. The secretion samples were subjected to thin layer chromatography. RNs of I. cairica were cryptic, having patches of nectar‐secreting trichomes, subglandular parenchyma cells and thick‐walled cells delimiting the nectary aperture. The glandular trichomes were peltate type and had typical ultrastructural features related to nectar secretion. The nectar is composed of sucrose, fructose and glucose. Nectar secretion was observed in young floral buds and continued as the flower developed, lasting until the fruit matured. The starch content of the subglandular tissue showed circadian variation, increasing during the day and decreasing at night. The plastids were distinct in different portions of the nectary. The continuous day–night secretory pattern of the RNs of I. cairica is associated with pre‐nectar source circadian changes in which the starch acts as a buffer, ensuring uninterrupted nectar secretion. This circadian variation may be present in other extrafloral nectaries and be responsible for full daytime secretion. We conclude that sampling time is relevant in ultrastructural studies of dynamic extranuptial nectaries that undergo various changes throughout the day.     

Gustatory responses of a specialist and a generalist grasshopper to terpenoids of Artemisia ludoviciana

Hypochlora alba (Dodge) is a specialist grasshopper that lives and feeds almost exclusively on the sage brush Artemisia ludoviciana Nutt., a plant mostly avoided by the generalist grasshopper Melanoplus sanguinipes (Fabr.). Analysis of leaves, seed heads, and glandular trichomes by gas chromatography-mass spectrometry revealed 1,8-cineole, camphor and borneol to be the major monoterpenes and achillin the major sesquiterpene lactone. These terpenoids increased over the growing season and were two to five times more concentrated in the seed heads than in the leaves. Gustatory choice tests showed a feeding stimulant(s) for H. alba to be present in extracts of A. ludoviciana and A. carruthii Wood, a closely related species that H. alba will feed upon, but not in a non-host species, A. filifolia Torr. This stimulant activity was found in a fraction containing primarily monoterpene hydrocarbons. Other fractions containing sesquiterpene lactones had antifeedant activity against M. sanguinipes. Tests with achillin showed the average foliar levels (ca. 2% dry weight) to be above the rejection threshold of the generalist (0.5%) but below that of the specialist (4%). Reproductive tissue contained average levels greater (ca. 7%) than the rejection threshold of either species.

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Résumé Hypochlora alba Dodge, orthoptère spécialiste, consomme presque exclusivement A. ludoviciana, plante produisant des terpènes en grandes quantités dans ses trichomes glandulaires. Cette plante n'est pas consommée par des orthoptères généralistes, comme Melanoplus sanguinpes Fabr. L'analyse d'extraits et de fractions de la plante en chromatographie en phase gazeuse associée à la spectrométrie de masse a révélé de nombreux monoterpènes (1,8-cinéole, camphre, bornéol et autres) et une grande quantité d'achilline, lactone sesquiterpène. Ces terpènes étaient 2 à 5 fois plus concentrés dans les organes reproducteurs de l'armoise que dans ses organes végétatifs. La concentration de terpènes dans les feuilles augmente de la plante jeune jusqu'à la maturité. Les plantes ont présenté une grande variabilité en concentrations relative et totale en terpènes. L'influence des terpènes dans la régulation du comportement alimentaire du spécialiste et du généraliste a été examinée par des tests de choix gustatif sur des disques de membrane. Des extraits de A. ludaviciana et de A. carruthii Wood,-espèce très voisine que H. alba peut consommer-, contenaient un (ou plusiers) phagostimulants de H. alba, tandis que A. filifolia Torr., espèce non consommée, n'en contenait pas. Cette activité stimulatrice était éluée dans la moins polaire des 5 fractions, qui contenait principalement les hydrocarbones monoterpènes. La prise de nourriture de M. sanguinipes a été stimulée par des extraits des 3 armoises examinées, et par les 3 premières fractions de A. ludoviciana, tandis que ses 2 dernières fractions, contenant les lactones sesquiterpènes, ont présenté une action phagodissuasive. Des tests avec l'achilline, principale lactone sesquiterpène, ont montré que sa concentration moyenne dans les feuilles (2% du poids frais) était supérieure au seuil de rejet du généraliste (0,5%), mais inférieure à celui du spécialiste (4%). La concentration moyenne des organes reproducteurs (7%) était supérieure au seuil de rejet des deux espèces.

     

Effect of temperature on glandular trichome exudate composition and pest resistance in geraniums

One inbred geranium line (71-18-6) which exhibits host plant resistance to the twospotted spider mite and foxglove aphid, becomes susceptible to these pests under some temperature conditions, while another resistant line (71-17-7) maintains its resistance. Resistance to these pests is conferred by the presence of glandular trichomes and the exudate they produce. The tall glandular trichome exudate of resistant geraniums has been identified as chiefly C₂₂ and C₂₄ unsaturated anacardic acids. Plants of a resistant line, a susceptible line and the temperature sensitive resistant line were exposed to three different temperature regimes and were analyzed chemically and for resistance using a foxglove aphid bioassay. Results indicate that the loss of resistance in the temperature sensitie line is not due to reduced production of the anacardic acids which comprise the exudate. Similarly, analysis of the exudate present on the leaf exterior indicate the loss of resistance in line 18-6 with increasing temperature is not the result of reduced translocation of the exudate to the trichome tip. Evidence is presented to support the hypothesis that loss of resistance in line 18–6 with increasing temperature is the result of an increased proportion of the shorter chain (C₂₂) anacardic acid in the trichome exudate, which reduces the viscosity of the material and causes it to flow from the trichome tips as the temperature increases. Presentation of the material as an exudate droplet at the trichome tip is apparently required for resistance.