Visualizing physiological parameters in cells and tissues using genetically encoded indicators for metabolites.

The study of metabolism is undergoing a renaissance. Since the year 2002, over 50 genetically-encoded fluorescent indicators (GEFIs) have been introduced, capable of monitoring metabolites with high spatial/temporal resolution using fluorescence microscopy. Indicators are fusion proteins that change their fluorescence upon binding a specific metabolite. There are indicators for sugars, monocarboxylates, Krebs cycle intermediates, amino acids, cofactors, and energy nucleotides. They permit monitoring relative levels, concentrations, and fluxes in living systems. At a minimum they report relative levels and, in some cases, absolute concentrations may be obtained by performing ad hoc calibration protocols. Proper data collection, processing, and interpretation are critical to take full advantage of these new tools. This review offers a survey of the metabolic indicators that have been validated in mammalian systems. Minimally invasive, these indicators have been instrumental for the purposes of confirmation, rebuttal and discovery. We envision that this powerful technology will foster metabolic physiology.

Structure and effective interactions in parallel monolayers of charged spherical colloids.

We study the microstructure and the effective interactions of model suspensions consisting of Yukawa-like colloidal particles homogeneously distributed in equally spaced parallel planar monolayers. All the particles interact with each other, but particle transfer between monolayers is not allowed. The spacing between the layers defines the effective system dimensionality. When the layer spacing is comparable to the particle size, the system shows quasi-three-dimensional behavior, whereas for large distances the layers behave as effective two-dimensional systems. We find that effective attractions between like-charged particles can be triggered by adjusting the interlayer spacing, showing that the distance between adjacent layers is an excellent control parameter for the effective interparticle interactions. Our study is based on Brownian dynamics simulations and the integral equations theory of liquids. The effective potentials are accounted for by exploiting the invariance of the Ornstein-Zernike matrix equation under contractions of the description, and on assuming that the difference between bare and effective bridge functions can be neglected. We find that the hypernetted chain approximation does not account properly for the effective interactions in layered systems.

Antennal Morphology and Localization of a Pheromone-Binding Protein of Lobesia botrana (Denis & Schiffermüller) (Lepidoptera: Tortricidae).

In the sensory system of insects, olfactory sensilla constitute important functional elements for discriminating odors. Therefore, we used light microscopy and scanning electron microscopy to investigate the morphology and distribution of sensilla in the antennae of Lobesia botrana (Denis & Schiffermüller). In addition, we studied the expression of the gene encoding for pheromone-binding protein 1 (LbotPBP1) by in situ hybridization. Lobesia botrana antennae are filiform and are subdivided into three segments: scape, pedicel, and flagellum. The number of flagellum and their overall length were significantly higher and longer in males than in females. Six morphological types of sensilla (trichodea, chaetica, coeloconica, auricillica, basiconica, and styloconica) were identified on the antennae of both sexes. Trichodea sensilla were the most abundant on the antennae of L. botrana, and three subtypes, discerned by their lengths, were observed. However, sensilla trichodea subtype III was only present in male antennae. Moreover, LbotPBP1 expression was restricted to this type of sensilla, thus confirming its olfactory role, specifically under the context of sexual pheromone perception.