Functional characterization of β-adrenergic and insulin receptor heteromers.

This study aimed to functionally characterize β-adrenergic (βAR) and insulin receptor (IR) heteromers in regard to β-arrestin 2 (βarr2) recruitment and cAMP signaling and to examine the involvement of the cytoplasmic portion of the IR β chain in heteromerization with βAR. Evidence for βAR:IR:βarr2 complex formation and the specificity of the IR:βarr2 interaction was first provided by bioinfomatics analysis. Receptor-heteromer investigation technology (HIT) then provided functional evidence of βAR:IR heterodimerization by showing isoproterenol-induced but not insulin-induced GFP-βarr2 recruitment to the βAR:IR complex; the IR:βarr2 interaction was found to only be constitutive.

Wood combustion particles induce adverse effects to normal and diseased airway epithelia.

Residential wood burning is a major source of poorly characterized, deleterious particulate matter, whose composition and toxicity may vary with wood type, burning condition and photochemical age. The causative link between ambient wood particle constituents and observed adverse health effects is currently lacking. Here we investigate the relationship between chemical properties of primary and atmospherically aged wood combustion particles and acute toxicity in human airway epithelial cells.

Demonstration of a direct interaction between β2-adrenergic receptor and insulin receptor by BRET and bioinformatics.

Glucose metabolism is under the cooperative regulation of both insulin receptor (IR) and β(2)-adrenergic receptor (β(2)AR), which represent the receptor tyrosine kinases (RTKs) and seven transmembrane receptors (7TMRs), respectively. Studies demonstrating cross-talk between these two receptors and their endogenous coexpression have suggested their possible interactions. To evaluate the effect of IR and prospective heteromerization on β(2)AR properties, we showed that IR coexpression had no effect on the ligand binding properties of β(2)AR; however, IR reduced β(2)AR surface expression and accelerated its internalization.

Mathematical models for quantitative assessment of bioluminescence resonance energy transfer: application to seven transmembrane receptors oligomerization.

The idea that seven transmembrane receptors (7TMRs; also designated G-protein coupled receptors, GPCRs) might form dimers or higher order oligomeric complexes was formulated more than 20 years ago and has been intensively studied since then. In the last decade, bioluminescence resonance energy transfer (BRET) has been one of the most frequently used biophysical methods for studying 7TMRs oligomerization. This technique enables monitoring physical interactions between protein partners in living cells fused to donor and acceptor moieties.

Real-time visualization of oxidative stress in a floating macrophyte Lemna minor L. exposed to cadmium, copper, menadione, and AAPH.

An ultra-sensitive digital imaging system was employed to visualize oxidative stress in intact L. minor plants exposed to Cd, Cu, menadione, AAPH, and ascorbate in real time. The increase of ROS production was assessed by measuring the rate of fluorescence intensity increases of the test medium supplemented with a fluorescing probe (dichlorofluorescein diacetate).

Growth, delayed fluorescence and pigment composition of four Prorocentrum minimum strains growing at two salinities.

Prorocentrum minimum is a potentially harmful and widely distributed marine dinoflagellate. Several P. minimum strains have already been studied, showing phylogenetical relations of strains isolated from the same geographical regions.

Delayed fluorescence as a measure of nutrient limitation in Dunaliella tertiolecta.

The applicability of the delayed fluorescence (DF) for the purpose of distinguishing the cells growing in different nutrient conditions was researched on the marine unicellular algae Dunaliella tertiolecta Butcher (Chlorophyta). The DF intensity (DFI), as a measure of living algal biomass, was compared with other biomass measures--the cell concentration, chlorophyll a and fluorescence. The photosynthetic activity index (PhAI), a non-dimensional physiological index of photosynthesis calculated from a combination of DFI and F(0) was introduced.

Antioxidative responses of duckweed (Lemna minor L.) to short-term copper exposure.

Goal, Scope And Background: Elevated concentrations of copper in the environment result in accumulation of the metal in plants and cause an increase in reactive oxidative species (ROS). The first response to elevated amounts of ROS is increased levels of enzymatic and non-enzymatic antioxidants that reduce oxidative stress. The aim of our study was to evaluate the early stages of antioxidative responses to the low copper concentrations usually present in moderately polluted environments.

Opsin oligomerization in a heterologous cell system.

Using bioluminescence resonance energy transfer (BRET) we studied opsin oligomerization in heterologous expression systems and quantitatively assessed its oligomerization state. BRET2 saturation and competition experiments were performed with live COS-7 cells expressing Rluc-and GFP2-tagged receptor constructs. BRET2 saturation curves obtained were hyperbolic, and the calculated oligomerization state (N = 1 for dimers) suggested that opsin (N = 1.