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Oil Glands (oil + gland)
Selected AbstractsOpisthonotal glands in the Camisiidae (Acari, Oribatida): evidence for a regressive evolutionary trendJOURNAL OF ZOOLOGICAL SYSTEMATICS AND EVOLUTIONARY RESEARCH, Issue 1 2009G. Raspotnig Abstract Paired, sac-like and typically large opisthonotal glands (syn. oil glands), mainly considered for chemical protection and communication, characterize the so-called ,glandulate Oribatida' which include the Parhyposomata, Mixonomata, Desmonomata and Brachypylina but also the Astigmata. Among these groups distinct evolutionary trends affect the morphology of glands and their secretion profiles, thereby rendering them highly informative characters with phylogenetic significance. One striking tendency, convergently occurring in a few glandulate groups, leads to the degeneration or even complete regression of opisthonotal glands. In this study, a first example of coherent evolutionary steps towards opisthonotal gland degeneration is described by using desmonomatan Camisiidae as a model: Opisthonotal glands in representatives of genus Platynothrus still show morphologically and chemically ancient conditions with fairly-well developed glandular reservoirs. Secretion patterns mainly consist of a characteristic set of terpenes and aromatics (,astigmatid compounds') as found in outgroups such as desmonomatan Trhypochthoniidae. Progressive states of regression of opisthonotal glands, along with a reduction of component-richness and amounts of secretions, occur in representatives of Heminothrus and, more conspicuously, in species of Camisia, most likely indicating a consistent evolutionary trend. This trend towards opisthonotal gland atrophy may be due to novel alternative and cheap strategies of passive defense in more-derivative camisiids , such as mechanical protection by encrustation of the cuticle , that possibly compensate for the lack of chemical defenses. Zusammenfassung Paarige, sackförmige und typischerweise große opisthosomatische Drüsen (syn. Öldrüsen), deren Sekrete hauptsächlich zum chemischen Schutz und zur Kommunikation dienen sollen, kennzeichnen die sogenannten glandulaten Hornmilben. Innerhalb dieser Hornmilbengruppe, die die Parhyposomata, Mixonomata, Desmonomata, Brachypylina, aber auch die astigmaten Milben umfasst, waren die Öldrüsen offensichtlich in morphologischer und chemischer Hinsicht deutlich unterschiedlichen evolutiven Trends unterworfen; damit sind Öldrüsen ein phylogenetisch außerordentlich wichtiger Merkmalskomplex in der Oribatiden-Systematik geworden. Eine auffällige Tendenz allerdings, die offensichtlich mehrmals konvergent auftritt, führt zur Rückbildung der Drüsen in bestimmten glandulaten Gruppen. In der vorliegenden Arbeit wird zum ersten Mal eine zusammenhängende Linie solcher Rückbildungsstadien am Beispiel der Camisiidae (Desmonomata) beschrieben: die weitgehend noch gut ausgebildeten Öldrüsen von Vertretern der Gattung Platynothrus zeigen morphologisch und chemisch ursprüngliche Merkmale. Sekretprofile bestehen hauptsächlich aus einem charakteristischen Set von Terpenen und Aromaten ("astigmatid compounds'), das auch in Außengruppen wie z.B. bei Trhypochthoniiden auftritt. Fortschreitende Stadien der Rückbildung von Öldrüsen, verbunden mit einer Verarmung der Sekretprofile und einer Verringerung an Sekretmengen, treten in Vertretern von Heminothrus und, noch auffälliger, bei verschiedenen Arten von Camisia auf: dieses Phänomen, übereinstimmend mit einem auf morphologischen Daten basierenden Systemvorschlag, wird als evolutiver Trend innerhalb der Camisiidae gedeutet. Dieser Trend zur Öldrüsenrückbildung ist möglicherweise mit einer alternativen Strategie passiver Verteidigung bei weiter abgeleiteten Camisiiden zu erklären, die Krustenbildungen aus Cerotegument und Bodenpartikeln auf der Körperöberfläche als mechanischen Schutz gegen Prädatoren nützen. Diese möglicherweise energetisch billige Variante könnte den Verlust chemischer Verteidigung über Öldrüsensekretion kompensieren. [source] Photosynthesis within isobilateral Eucalyptus pauciflora leavesNEW PHYTOLOGIST, Issue 4 2006John R. Evans Summary ,,Adult Eucalyptus pauciflora leaves are vertically displayed. They have multiple palisade cell layers beneath both surfaces, interrupted by numerous oil glands. Here, we characterized light absorption, chlorophyll, photosynthetic capacity and CO2 fixation profiles through these leaves. ,,Multiple chlorophyll fluorescence images of leaves viewed in cross-section were made by applying light from different directions. 14CO2 labelling, followed by paradermal cryosectioning, was used to measure profiles of photosynthesis. ,,Photosynthetic capacity peaked 75 µm into the mesophyll beneath each surface and was lowest in the centre of the 600-µm-thick leaf. Predictions by a multilayer model using Beer's law matched the observed profiles of 14C fixation. When constrained to the horizontal, a vertically acclimated leaf gains only 79% of the daily photosynthesis achieved by a horizontally acclimated leaf. However, it outperforms the horizontally acclimated leaf when both are oriented vertically. ,,Each half of the observed profile of photosynthetic capacity closely matches the profile of light absorption through the leaf with unilateral illumination to that surface. Derivation of biochemical parameters from gas exchange measured under unilateral illumination would underestimate the real photosynthetic capacity of these leaves by 21%. [source] Seasonal, populational and ontogenic variation in the volatile oil content and composition of individuals of Origanum vulgare subsp.PHYTOCHEMICAL ANALYSIS, Issue 5 2004Hirtum, assessed by GC headspace analysis, by SPME sampling of individual oil glands Abstract Small-scale GC headspace analyses combined with SPME sampling of individual oil glands have been used to measure the variation in volatile content and composition in and within different oregano plants as affected by age, season and developmental state. The main monoterpenes found were p -cymene, carvacrol and their precursor , -terpinene. The early season preponderance of p -cymene over carvacrol was reversed as the season progressed and this pattern could also be seen at any time within the plant, from the latest leaves to be produced (low in cymene) to the earliest (high in cymene). Seedlings from the same mother plant developed this pattern at different rates. Within individual leaves the pattern was not observed, even within the youngest developing leaves. However it was found that the oil composition of individual glands within a single leaf varied considerably, most notably in respect of the production of carvacrol and its isomer thymol. Copyright © 2004 John Wiley & Sons, Ltd. [source] Diversity of essential oil glands of clary sage (Salvia sclarea L., Lamiaceae)PLANT BIOLOGY, Issue 4 2008C. Schmiderer Abstract The Lamiaceae is rich in aromatic plant species. Most of these species produce and store essential oils in specialised epidermal oil glands, which are responsible for their specific flavour. Two types of glands producing essential oil and possessing different morphological structure can be found in Salvia sclarea: peltate and capitate glands. The content of single oil glands from different positions on the plant (corolla, calyx and leaf) were sampled using an SPME fibre and analysed by gas chromatography in order to study variability of the essential oil composition. It was found that the composition of terpenoids is quite variable within an individual plant. Capitate oil glands mainly produce three essential oil compounds: the monoterpenes linalool and linalyl acetate, and the diterpene sclareol. Peltate oil glands, however, accumulate noticeable concentrations of sesquiterpenes and an unknown compound (m/z = 354). Furthermore, the oil composition varies within each gland type according to the plant organ. Linalool and linalyl acetate are characteristic substances of flowers, whereas the sesquiterpenes occur in higher proportions in leaves. Even within one gland type on a single leaf, the chemical variability is exceedingly high. [source] | ||||||||||