Dopamine beta-hydroxylase like immunoreactive cells in the frog taste disc

We immunohistochemically examined the existence of dopamine beta-hydroxylase (DBH), a noradrenalin (NA)-synthesizing enzyme from dopamine, in the taste disc of frog, Rana catesbeiana. DBH-like immunoreactive cells were located in the intermediate layer in the taste disc; the cells showed an apical process reaching the surface of the disc and one or several basal processes. Cells with a thick apical process and those with a thin apical process were both immunoreactive: these cells corresponded to type II and III receptor cells of the frog taste disc. Immunoreactive granules were observed in the cytoplasm of those cells. In the frog taste disc, only type III cells are reported to have afferent synapses with the nerve via basal processes but those basal processes have not been reported in type II cells. In the present study, we found that type II-like cells possessed a long basal process extending toward the basal lamina. Mucous (type Ia) cells, wing (type Ib) cells, and glia-like sustentacular (type Ic) cells were all immunohistochemically unreactive. The present observations support the argument that NA (or adrenalin) may work as a chemical transmitter in the frog taste organ.     

Decoralin, a novel linear cationic alpha-helical peptide from the venom of the solitary eumenine wasp Oreumenes decoratus

A novel peptide, decoralin, was isolated from the venom of the solitary eumenine wasp Oreumenes decoratus. Its sequence, Ser-Leu-Leu-Ser-Leu-Ile-Arg-Lys-Leu-Ile-Thr, was determined by Edman degradation and corroborated by solid-phase synthesis. This sequence has the characteristic features of linear cationic alpha-helical peptides; rich in hydrophobic and basic amino acids with no disulfide bond, and accordingly, it can be predicted to adopt an amphipathic alpha-helix secondary structure. In fact, the CD spectra of decoralin in the presence of TFE or SDS showed a high alpha-helical conformation content. In a biological evaluation, decoralin exhibited a significant broad-spectrum antimicrobial activity, and moderate mast cell degranulation and leishmanicidal activities, but showed virtually no hemolytic activity. A synthetic analog with C-terminal amidation showed a much more potent activity in all the biological assays.     

Assessment of prion inactivation by combined use of Bacillus-derived protease and SDS

Prions, infectious agents causing transmissible spongiform encephalopathy, retain infectivity even after undergoing routine sterilization processes. We found that MSK103 protease, identified in our previous study, effectively reduces infectivity and the level of misfolded isoform of the prion protein in scrapie-infected brain homogenates in the presence of SDS. The treatment therefore can be applied to the decontamination of thermolabile instruments.     

Immunoassay using microfluid filters constructed by deep X-ray lithography

Microfluid filters were fabricated, which possessed 2,100 cylindrical through-bores (psi 40 microm) in 200 microm-thickness polymethylmethacrylate (PMMA) sheets (psi 3 mm), by deep X-ray lithography using synchrotron radiation. To evaluate the microfluid filters as a device for an immunoassay, we bound the goat anti-mouse immunoglobulin G (IgG) antibody to the surface of the filters, and set the filters between reaction vessels stacked vertically in a microreactor. An enzyme-linked immunosorbent assay (ELISA) of mouse IgG using the goat anti-mouse IgG/horseradish-peroxidase (HRP) conjugate indicated that mouse IgG could be quantitatively detected in the range of 0-100 ng/ml, demonstrating the applicability of vertical microfluidic operation to the immunoassay.     

Electroconductive materials as biomimetic platforms for tissue regeneration

In many diseases, tissue regeneration is compromised and/or insufficient to restore tissue/organ function. Therefore, novel regenerative therapies are being developed to enhance resident and transplanted cell proliferation and functional differentiation. Numerous biomaterials engineered to include nanocomponents have emerged as promising candidates to fulfil the need of mimicking the properties of the healthy extracellular matrix. This is particularly important for tissues that require electroconductive support to achieve optimal cellular function, such as muscles and neurons. In this review, we summarize and discuss the current state-of-the-art for electroconductive materials in tissue regeneration, with particular emphasis on materials containing nanocomponents.     

Molecular interplays involved in the cellular uptake of octaarginine on cell surfaces and the importance of syndecan-4 cytoplasmic V domain for the activation of protein kinase Cα

Arginine-rich cell-penetrating peptides (CPPs) are promising carriers for the intracellular delivery of various bioactive molecules. However, many ambiguities remain about the molecular interplays on cell surfaces that ultimately lead to endocytic uptake of CPPs. By treatment of cells with octaarginine (R8), enhanced clustering of syndecan-4 on plasma membranes and binding of protein kinase Cα (PKCα) to the cytoplasmic domain of syndecan-4 were observed; these events potentially lead to the macropinocytic uptake of R8. The cytoplasmic V domain of syndecan-4 made a significant contribution to the cellular uptake of R8, whereas the cytoplasmic C1 and C2 domains were not involved in the process.     

IRBIT: A regulator of ion channels and ion transporters

IRBIT (also called AHCYL1) was originally identified as a binding protein of the intracellular Ca^2 + channel inositol 1,4,5-trisphosphate (IP₃) receptor and functions as an inhibitory regulator of this receptor. Unexpectedly, many functions have subsequently been identified for IRBIT including the activation of multiple ion channels and ion transporters, such as the Na⁺/HCO₃⁻ co-transporter NBCe1-B, the Na⁺/H⁺ exchanger NHE3, the Cl⁻ channel cystic fibrosis transmembrane conductance regulator (CFTR), and the Cl⁻/HCO₃⁻ exchanger Slc26a6. The characteristic serine-rich region in IRBIT plays a critical role in the functions of this protein. In this review, we describe the evolution, domain structure, expression pattern, and physiological roles of IRBIT and discuss the potential molecular mechanisms underlying the coordinated regulation of these diverse ion channels/transporters through IRBIT. This article is part of a Special Issue entitled: Calcium signaling in health and disease. Guest Editors: Geert Bultynck, Jacques Haiech, Claus W. Heizmann, Joachim Krebs, and Marc Moreau.