Analysis of Slow Hyperpolarizing Potentials in Frog Taste Cells Induced by Glossopharyngeal Nerve Stimulation

Chemical Senses, 29,     

Wiring diagrams of MAPK regulation by MEKK1, 2, and 3.

Mitogen-activated protein kinase (MAPK) pathways are activated by a plethora of stimuli. The literature is filled with papers describing the activation of different MAPKs by almost any stimulus or insult imaginable to cells. In this review, we use signal transduction wiring diagrams to illustrate putative upstream regulators for the MAPK kinase kinases, MEKK1, 2, and 3. Targeted gene disruption of MEKK1, 2, or 3 defined phenotypes for each MEKK associated with loss of specific MAPK regulation. Genetic analysis of MEKK function clearly defines specific components of the wiring diagram that require MEKK1, 2, or 3 for physiological responses. We propose that signal transduction network wiring diagrams are valuable tools for hypothesis building and filtering physiologically relevant phenotypic responses from less connected protein relations in the regulation of MAPK pathways.     

Effect of surfactants on stability of Acinetobacter johnsonii S35 and Oligotropha carboxidovorans S23 coaggregates

The effect of anionic (sodium dodecyl sulphate or SDS) and cationic (cetyltrimethylammonium bromide or CTAB) surfactants on the stability of binary bacterial coaggregates comprising Acinetobacter johnsonii S35 and Oligotropha carboxidovorans S23 (both sewage sludge isolates) was studied and compared with that on the complex sewage sludge flocs. Both SDS and CTAB enhanced the bacterial coaggregation at their lower concentrations of 0.2 and 0.07 mg ml(-1), respectively. However, complete deflocculation of coaggregates was observed at 1 mg ml(-1) SDS and 0.3 mg l(-1) CTAB concentrations. Further, sewage sludge flocs did not deflocculate in the presence of CTAB, although a concentration-dependent deflocculation was observed in the presence of SDS. A. johnsonii S35 and O. carboxidovorans S23 cells were separately pretreated (prior to coaggregation) with the surfactants. In spite of the partial (complete) loss of viability during SDS (CTAB) pretreatment, washed cells still retained hydrophobic character and displayed significant coaggregation (aggregation index ranging from 84% to 97% in comparison to 96% in the case of non-treated cells), demonstrating reversibility of the surfactant induced deflocculation. Further, when exposed to lower concentration of surfactants (0.2 mg ml(-1) SDS), coaggregates were more resistant (76% viability) as compared to the individual partner (S35: 52%; S23: 39% viability). Since the coaggregates are stable and provide protection from surfactants at lower concentrations (those normally expected in the sewage treatment plants), their presence as well as a sustained role in the sewage sludge bioflocculation is evident.     

Carbohydrate-recognition domains of galectin-9 are involved in intermolecular interaction with galectin-9 itself and other members of the galectin family

Galectin-9 (Gal-9) is a tandem-repeat-type member of the galectin family associated with diverse biological processes, such as apoptosis, cell aggregation, and eosinophil chemoattraction. Although the detailed sugar-binding specificity of Gal-9 has been elucidated, molecular mechanisms that underlie these functions remain to be investigated. During the course of our binding study by affinity chromatography and surface plasmon resonance (SPR) analysis, we found that human Gal-9 interacts with immobilized Gal-9 in the protein-protein interaction mode. Interestingly, this intermolecular interaction strongly depended on the activity of the carbohydrate recognition domain (CRD), because the addition of potent saccharide inhibitors abolished the binding. The presence of multimers was also confirmed by Ferguson plot analysis of result of polyacrylamide gel electrophoresis and matrix-assisted laser-desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS). Moreover, this intermolecular interaction was observed between Gal-9 and other galectin members, such as Gal-3 and Gal-8, but not Gal-1. Because such properties have not been reported yet, they may explain an unidentified mechanism underlying the diverse functions of Gal-9.     

Pollination system and its significance on isolation and hybridization in JapaneseEpimedium (Berberidaceae)

Observations on native populations of JapaneseEpimedium have revealed that two types of effective pollinators can be recognized. One of the two types, which consists of small bees (mainlyAndrena spp. andLasioglossum spp.), is characterized by nondiscriminating behavior for collecting pollen and is commonly found inEpimedium. The other type, which comprises medium sizedTetralonia nipponensis and largerBombus diversus queens as main components, showed flower-dependent foraging fidelity associated with nectar-sucking behavior.T. nipponensis with a shorter proboscis pollinated flowers with a shorter spur ofE. trifoliatobinatum and of a part ofE. s sempervirens, while the queen ofB. diversus with a longer proboscis pollinated longer spurred flowers ofE. grandiflorum andE. sempervirens. In the populations of putative hybrid-derivatives which show gradational variations of spur length, bees of the pollencollecting type pollinated any flower non-discriminately while bees of the nectar-foraging type tended to visit the flowers with spur lengths corresponding to their proboscis length. These observations suggest that the pollen-collecting bees play an important role for gene flow among theEpimedium species, and the nectar-foraging bees reinforce the isolation between the species by their selective pollination. Reproductive isolation between species ofEpimedium is discussed in relation with some practical behavior, such as flying power, of the pollinators.     

Stress fibers in the mesenteric mesothelial cells of the large intestine of the bullfrog,Rana catesbeiana

Summary Actin-containing cytoplasmic fibers were visualized in the mesenteric mesothelial cells of the large intestine of bullfrog tadpoles by rhodamine-phalloidin staining of en face preparations of mesothelial cells. These fibers were concurrently stained by immunofluorescence using antibodies to myosin or -actinin. Electron microscopy showed the presence of bundles of microfilaments in the basal cytoplasm of the cells. Such fibers in the mesothelial cells may be comparable to the stress fibers present in cultured cells. The mesothelial cells initially formed axially oriented stress fibers when they changed from a rhombic to a slender spindle-like shape. On the other hand, stress fibers disappeared as cells transformed from elongated to polygonal shapes during the period of metamorphic climax. Expression of stress fibers in these cells appears to be related to the degree of tension loaded on the mesentery, which may be generated by mesenteric winding. These stress fibers in the mesothelial cells may serve to regulate cellular transformation. They may also help to maintain cellular integrity by strengthening the cellular attachment to subepithelial tissue against tensile stress exerted on the mesentery.     

Immunocytochemical localization of callose in the germinated pollen ofCamellia japonica

Summary A polyclonal antibody against -1,3-glucan, callose, extracted from the pollen tube wall ofCamellia japonica was raised in mice and, using it as a probe, the localization of callose in the germinated pollen was studied. By confocal laser scanning microscopy, callose was found in the tip region of the pollen tube and the tube wall; the immuno-fluorescence in the tube wall was less toward the base of the tube. In contrast, the tip region did not fluoresce although the whole of the tube wall did strongly with aniline blue, the specific dye for callose. Immuno-electron microscopy showed that callose was also found in Golgi vesicles which concentrated in the tip region of the pollen tube, the inner layer of the tube wall, callose plugs, and Golgi vesicles in the pollen grain. Immuno-gold labeling was often detected on the fibrous structures in Golgi vesicles and callose plugs. Based on these results, the participation of Golgi vesicles in the formation of the tube wall and callose plugs was discussed.Abbreviation TBS Tris-buffered saline - Tris Tris(hydroxy-methyl)-aminomethane - PBS phosphate-buffered saline - BSA bovine serum albumin - ELISA enzyme-linked immunosorbent assay - CLSM confocal laser scanning microscopy - DP degree of polymerization     

Preface

Sleep and Biological Rhythms -     

Cryopreservation of rat MSCs by use of a programmed freezer with magnetic field

Mesenchymal stem cells (MSCs) can be used for the regeneration of various tissues and cryopreservation of MSCs is so important for regenerative medicine. The purpose of this study was to evaluate the influences of cryopreservation on MSCs by use of a programmed freezer with a magnetic field (CAS freezer). MSCs were isolated from bone marrow of rat femora. The cells were frozen by a CAS freezer with 10% dimethyl sulfoxide (Me2SO) and cryopreserved for 7 days at a temperature of −150 °C. Immediately after thawing, the number of survived cells was counted. The cell proliferation also examined after 48 h culture. Next, MSCs were frozen by two different freezers; CAS freezer and a conventional programmed freezer without magnetic field. Then, osteogenic and adipogenic differentiations of cryopreserved cells were examined. As a result, survival and proliferation rates of MSCs were significantly higher in CAS freezer than in the non-magnetic freezer. Alizarin positive reaction, large amount of calcium quantification, and greater alkaline phosphatase activity were shown in both the non-cryopreserved and CAS groups after osteogenic differentiation. Moreover, Oil Red O staining positive reaction and high amount of PPARγ and FABP4 mRNAs were shown in both the non-cryopreserved and CAS groups after adipogenic differentiation. From these findings, it is shown that a CAS freezer can maintain high survival and proliferation rates of MSCs and maintain both adipogenic and osteogenic differentiation abilities. It is thus concluded that CAS freezer is available for cryopreservation of MSCs, which can be applied to various tissue regeneration.