Insect feeding deterrent activity of lignans and related phenylpropanoids with a methylenedioxyphenyl (piperonyl) structure moiety

The antifeedant activity of a series of lignan lactones, hemiacetals, ethers, and alcohols derived from yatein and cubebin, together with structurally related phenylpropanoids and phenolics possessing a methylenedioxyphenyl (piperonyl) moiety, was tested against selected stored products pests: Sitophilus granarius L. (Coleoptera: Curculionidae), Tribolium confusum Duv. (Coleoptera: Tenebrionideae), and Trogoderma granarium Ev. (Coleoptera: Dermestridae). The relation between molecular structure and antifeedant activity was examined and implication of the piperonyl moiety is assessed. The compounds represent either natural substances isolated from plants (Libocedrus yateensis Guillaumin and Piper cubeba L.) or their structural analogues prepared by simple chemical transformations as well as compounds selected from commercially available sources. Natural lignan lactones with methoxy and/or methylenedioxy substituents showed significant activity that is strong enough to affect plant - insect interactions. Presence of polar substituents, especially hydroxy or glycosyl groups, often reduce the activity. Non-polar substituents, such as methoxy or methylenedioxy groups, enhance the activity not only in lignans but also in simple phenylpropanoids. The most active compound was synthetic piperonylbutoxide.     

Quantitative In Situ Detection of Phosphoproteins in Fixed Tissues Using Quantum Dot Technology

Detection and quantitation of phosphoproteins (PPs) in fixed tissues will become increasingly important as additional inhibitors of protein kinases enter clinical use and new disease entities are defined by molecular changes affecting PP levels. We characterize fixation conditions suitable for accurate PP quantitation that are achievable in a clinical laboratory and illustrate the utility of in situ quantitation of PPs by quantum dot (QD) nanocrystals in two models: (1) a therapeutic model demonstrating effects of a targeted therapeutic (quantitative reduction of phospho-GSK3β) in xenografts treated with enzastaurin; and (2) a diagnostic model that identifies elevated levels of nuclear phospho-STAT5 in routine bone marrow biopsies from patients with acute myeloid leukemia based on the presence of the activating FLT3-ITD mutation. Finally, we document production of a well-characterized tissue microarray of widely available cell lines as a multilevel calibrator for validating numerous phosphoprotein assays. QD immunofluorescence is an ideal method for in situ quantitation of PPs in fixed samples, providing valuable cell type–specific and subcellular information about pathway activation in primary tissues. (J Histochem Cytochem 57:701–708, 2009)     

Functional analysis of phospholipase Dδ family in tobacco pollen tubes

Phosphatidic acid (PA), an important signalling and metabolic phospholipid, is predominantly localized in the subapical plasma membrane (PM) of growing pollen tubes. PA can be produced from structural phospholipids by phospholipase D (PLD), but the isoforms responsible for production of PM PA were not identified yet and their functional roles remain unknown. Following genome‐wide bioinformatic analysis of the PLD family in tobacco, we focused on the pollen‐overrepresented PLDδ class. Combining live‐cell imaging, gene overexpression, lipid‐binding and structural bioinformatics, we characterized five NtPLDδ isoforms. Distinct PLDδ isoforms preferentially localize to the cytoplasm or subapical PM. Using fluorescence recovery after photobleaching, domain deletion and swapping analyses we show that membrane‐bound PLDδs are tightly bound to PM, primarily via the central catalytic domain. Overexpression analyses suggested isoform PLDδ3 as the most important member of the PLDδ subfamily active in pollen tubes. Moreover, only PLDδ3 shows significant constitutive PLD activity in vivo and, in turn, PA promotes binding of PLDδ3 to the PM. This forms a positive feedback loop leading to PA accumulation and the formation of massive PM invaginations. Tightly controlled production of PA generated by PLDδ3 at the PM is important for maintaining the balance between various membrane trafficking processes that are crucial for plant cell tip growth.     

Evidence for transcytosis of exogenous superoxide dismutase and catalase from coronary capillaries into dog myocytes

Infusion of superoxide dismutase (SOD) and catalase (CAT) into the coronary circulation protects myocardial tissue from free radical injury and improves recovery of myocardial function after a short episode of ischaemia. To investigate the ultrastructure of myocardium treated with SOD and CAT, these enzymes were injected into the left atrium of dogs prior to and during 15 min of regional myocardial ischaemia, allowing 30 min of reperfusion, and then fixing the tissue for electron microscopy. The exogenous SOD + CAT was found to promote recovery of both function and structure in these hearts. In addition, electron dense material was unexpectedly found in vesicles of capillary endothelia, between capillaries and myocyte, and in vesicles within myocytes. This occurred only in hearts treated with SOD and/or CAT, suggesting SOD and CAT was concentrated and transported across the capillary endothelium and into myocytes. The rate of transcytosis, as measured by the number of intra-endothelial vesicles, was increased in tissue subjected to ischaemia and reperfusion in the presence of SOD and CAT. These observations suggest transcytosis of SOD and CAT is an important part of the process by which these enzymes provide protection to myocardium during reperfusion after ischaemia.