Role of long-chain hydrocarbons in the aggregation behaviour of Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae)

in Journal of Insect Physiology (2012)

The multicoloured Asian ladybeetles, Harmonia axyridis (Pallas), form large aggregations inside dwellings to survive cold winters, causing annoyances to householders from their number and sometimes the ... [more ▼]

The multicoloured Asian ladybeetles, Harmonia axyridis (Pallas), form large aggregations inside dwellings to survive cold winters, causing annoyances to householders from their number and sometimes the induction of allergic reactions. Migratory flight and macrosite choice of this species is well documented. H. axyridis shows a hypsotactic behaviour and a clear preference for contrasting visual elements. However, how the microsite is selected remains undocumented, although a better understanding of the implicated factors could lead to the development of new control methods for this pest. In this work, we have hypothesized that non-volatile compounds are involved in the microsite choice and the aggregation process of this beetle. Long chain hydrocarbons were identified inside aggregation sites, comprising saturated and unsaturated homologues. An aggregation bioassay was then conducted on overwintering individuals, highlighting the retention capacity of the previously cited compounds on the tested ladybeetles. Additional investigations have shown that H. axyridis males and females, originating from overwintering sites, deposit a similar blend of molecules while walking. A Y-shaped tube assay revealed that this blend is used by male and female congeners as cue, allowing individuals to orientate towards the treated side of the olfactometer. These results suggest the use of two different blends of long chain hydrocarbons by H. axyridis during its aggregative period, the first one to lead conspecifics towards aggregation sites (microsites) and the second to ensure the cohesion of the aggregation. These findings support the potential use of these blends, in association with volatiles, in the design of traps in order to control infestations of this species in dwellings. [less ▲]

Role of lysine versus arginine in enzyme cold-adaptation: Modifying lysine to homo-arginine stabilizes the cold-adapted alpha-amylase from Pseudoalteramonas haloplanktis

in Proteins-Structure Function and Bioinformatics (2006), 64(2), 486-501

The cold-adapted alpha-amylase from Pseudoalteromonas haloplanktis (AHA) is a multidomain enzyme capable of reversible unfolding. Cold-adapted proteins, including AHA, have been predicted to be ... [more ▼]

The cold-adapted alpha-amylase from Pseudoalteromonas haloplanktis (AHA) is a multidomain enzyme capable of reversible unfolding. Cold-adapted proteins, including AHA, have been predicted to be structurally flexible and conformationally unstable as a consequence of a high lysine-to-arginine ratio. In order to examine the role of low arginine content in structural flexibility of AHA, the amino groups of lysine were guanidinated to form homoarginine (hR), and the structure-function-stability properties of the modified enzyme were analyzed by transverse urea gradient-gel electrophoresis. The extent of modification was monitored by MALDI-TOF-MS, and correlated to changes in activity and stability. Modifying lysine to hR produced a conformationally more stable and less active a-amylase. The k(cat) of the modified enzyme decreased with a concomitant increase in Delta H-# and decrease in K-m. To interpret the structural basis of the kinetic and thermodynamic properties, the hR residues were modeled in the AHA X-ray structure and compared to the X-ray structure of a thermostable homolog. The experimental properties of the modified AHA were consistent with K106hR forming an intra-Domain B salt bridge to stabilize the active site and decrease the cooperativity of unfolding. Homo-Arg modification also appeared to alter Ca2+ and Cl- binding in the active site. Our results indicate that replacing lysine with hR generates mesophilic-like characteristics in AHA, and provides support for the importance of lysine residues in promoting enzyme cold adaptation. These data were consistent with computational analyses that show that AHA possesses a compositional bias that favors decreased conformational stability and increased flexibility. [less ▲]

Role of Matrix, Fibroblasts and Type Iv Collagenases in Tumor Progression and Invasion

in Pathology - Research & Practice (1994), 190(9-10), 934-41

We have studied the role of the extracellular matrix and host cells in tumor progression and tumor invasion. Our results emphasize the importance of tumoral cell-host cell interactions during this process ... [more ▼]

We have studied the role of the extracellular matrix and host cells in tumor progression and tumor invasion. Our results emphasize the importance of tumoral cell-host cell interactions during this process. Addition of human fibroblasts and/or basement membrane components to human mammary adenocarcinoma cells, when injected into athymic nude mice, results in an increase of take and growth rate of the tumors. Peritumoral extracellular matrix is remodeled through multiple mechanisms: overproduction of matrix components by fibroblasts, enhanced fibroblasts proliferation, modulation of interstitial collagenase production by fibroblasts and retraction of the matrix by tumoral cells. The degradation of basement membranes during the metastatic process is often associated with the secretion of proteolytic enzymes. The 72 kDa type IV collagenase, a metalloproteinase, can be produced by some tumoral cells. However, it appears also to be secreted by peritumoral stromal fibroblasts under the influence of tumoral cells. We have demonstrated the existence of a binding site for this enzyme on the membrane of mammary tumoral cells. These results suggest a cooperation between tumor cells and fibroblasts during basement membrane destruction. [less ▲]

The role of meiofauna in energy transfer in a Mediterranean seagrass bed (Calvi, Corsica

Poster (2010, October 22)

Meiofaunal communities of the endemic Mediterranean seagrass, <u> Posidonia oceanica </u>, were sampled in five different habitats characterised by different degradation level of macrophytodetritus. In ... [more ▼]

Meiofaunal communities of the endemic Mediterranean seagrass, <u> Posidonia oceanica </u>, were sampled in five different habitats characterised by different degradation level of macrophytodetritus. In term of abundance, harpacticoid copepods represent half of the community followed by nematodes and polychaetes. Two meiofauna communities were distinguished: (1) a benthic community of meiofauna, living in the sediment or on highly fragmented macrophytodetritus, and (2) a foliar, epiphytal community associated with seagrass leaves and low fragmented macrophytodetritus leaves. They differed significantly in their harpacticoid copepod family composition. The benthic community consisted mainly of families like Tisbidae and Miraciidae, while the epiphytal community was dominated by families like Thalestridae and Laophontidae. These differences in composition may also imply a differential functional diversity. Trophic biomarkers (stable isotopes, fatty acids) were used to identify the major sources of organic matter contributing to the copepods diet and hence to gain insight in the overall carbon flux. Harpacticoid copepods showed preferences to feed upon the epiphytal biofilm community composed of bacteria, diatoms, fungi and microalgae. Copepods used the seagrass and detritus material merely as substrate, but were attracted to the biofilm rather than the plant material which is rich in structural carbohydrates difficult to assimilate by animals (i.e. lignin, cellulose, ...). Since harpacticoid copepods showed to use different sources of carbon, unravelling the contribution of each of them and the role of the degradation level of the detritus for food selectivity is the next step forward. [less ▲]

The role of melanin-concentrating hormone in conditioned reward learning

in European Journal of Neuroscience (2012), 36

The role of memory traces quality in directed forgetting: A comparison of young and elderly participants using the item procedure

Poster (2013)

Role of methalothionein in irradiated human rectal carcinoma.

in Cancer (2002), 95(5), 1003-1008

BACKGROUND. Metallothioneins (MT) are low-molecular weight, metal-binding proteins that play a role in cellular proliferation and differentiation, as well as in cellular defense mechanisms. They act as ... [more ▼]

BACKGROUND. Metallothioneins (MT) are low-molecular weight, metal-binding proteins that play a role in cellular proliferation and differentiation, as well as in cellular defense mechanisms. They act as scavengers of free radicals produced by irradiation. A number of in vitro and in vivo studies have linked overexpression of cellular MT with tumor cell resistance to radiation. This is the first study that investigates whether MT expression is involved in the radioresistance of rectal carcinoma. METHODS. Using a mouse monoclonal antibody, MT expression was analyzed by immunohistochemistry on surgical samples (n 85) from 85 patients with locally advanced rectal carcinoma who were treated preoperatively with a hyperfractionated and accelerated radiotherapy schedule and on tumor biopsies (n 13) obtained before treatment. The potential correlations between MT expression and pathologic variables and survival were examined. RESULTS. MT were expressed strongly in both the cytoplasm and nucleus of tumor cells in 7 biopsy and 42 surgical samples. A comparison of MT expression in biopsy and surgical specimens showed that MT expression did not change after irradiation in most cases. Against all expectations, MT were expressed more frequently in tumors from responders than in those from the nonresponders (P 0.02). There was no correlation between MT expression and tumor stage, histology after radiotherapy, or survival. CONCLUSION. These findings do not support the hypothesis that MT overexpression at the end of radiotherapy is a marker for radiation resistance. Cancer 2002;95: 1003–8. © 2002 American Cancer Society. DOI 10.1002/cncr.10780 [less ▲]

Role of Microsporum canis secreted proteases in adherence to and invasion of epidermis

Conference (2010)

Role of myo-inositol phosphate synthase and sucrose synthase genes in plant seed development

in Gene (2009), 439

Role of Neuropeptides in Acetylcholine-Induced Edema in Isolated and Perfused Rabbit Lungs

in Journal of Pharmacology and Experimental Therapeutics (The) (1993), 266(2), 483-491

Changes in pulmonary endothelial permeability and in microvascular hemodynamics in response to cumulative concentrations of acetylcholine (ACh) (10(-8) M to 10(-5) M) were investigated in isolated ... [more ▼]

Changes in pulmonary endothelial permeability and in microvascular hemodynamics in response to cumulative concentrations of acetylcholine (ACh) (10(-8) M to 10(-5) M) were investigated in isolated, perfused rabbit lungs. The total pressure gradient was partitioned into four components: arterial, pre- and postcapillary and venous. The capillary filtration coefficient (Kf, c) also was evaluated. ACh caused a significant increase in arterial and precapillary pressures at concentrations higher than 3 x 10(-6) M. The total pressure gradient and precapillary were significantly increased whereas arterial, postcapillary and venous pressure gradient remained unchanged. In papaverine (3 x 10(-4) M)-pretreated lungs, the vasoconstriction was abolished and a concentration-dependent increase in Kf,c was recorded from 10(-8) to 10(-5) M ACh. This reaction was accompanied by pulmonary edema. Atropine, indomethacin, aspirin, ketanserin, clonidine, morphine and (+/-)-CP 96-345, an antagonist of neurokinin NK1 receptors, completely prevented the effects of ACh on Kf,c. In contrast, cromolyn sodium and SR48968, a neurokinin NK2 antagonist, did not inhibit the response to ACh. Terfenadine together with cimetidine had a partially inhibitory effect. Changes in the Kf, c similar to those observed with ACh were induced by capsaicin (10(-4) M) by exogenous substance P (10(-7) M) and by 5-hydroxytryptamine (5-HT) (10(-4) M). The effects of SP were inhibited by aspirin, (+/-)-CP 96,345 and ketanserin, but not by atropine and antihistaminics. 5-HT effects were prevented by aspirin and not by (+/-)-CP 96,345. It was concluded that ACh-induced pulmonary edema was due to an increase in the capillary filtration coefficient.(ABSTRACT TRUNCATED AT 250 WORDS) [less ▲]