Histological and ultrastructural studies of the effects of tachykinins on protein secretion from the lingual epithelium and the lingual gland of the Tokyo daruma pond frog (Rana porosa porosa)

Ribosomal RNA gene (rDNA) loci, including those of nucleolus-forming 18S, 5.8S and 28S (major) and non-nucleolus-forming 5S (minor) rDNA, were assigned using fluorescence in situ hybridization (FISH) to the embryonic chromosomes of rainbow trout (Oncorhynchus mykiss), masu salmon (O. masou), brook trout (Salvelinus fontinalis) and Japanese huchen (Hucho perryi). In these species, the minor rDNA loci were located basically on 2-4 chromosome pairs, whereas the major rDNA loci were found essentially on one chromosome pair, except for the brook trout. Its major rDNA loci were dispersed on about half of the chromosome complement, showing a considerable interindividual variation in the number and location. The major and minor rDNA loci were separated onto different chromosomes in the examined species, except for the rainbow trout, in which one chromosome pair had tandemly aligned minor and major rDNA loci. Chromosome regions containing both kinds of rDNA loci in each species were found to be stained with C-banding, showing an association of these loci with heterochromatin. Comparison of the assigned major rDNA loci and sequentially detected silver (Ag)-stained nucleolar organizer regions (AgNORs) in all the species revealed a considerable polymorphism in the number and size of AgNORs among or within those loci, suggesting a possible inter- or intralocus inactivation of the major rDNAs.     

A target of phosphatidylinositol 3,4,5-trisphosphate with a zinc finger motif similar to that of the ADP-ribosylation-factor GTPase-activating protein and two pleckstrin homology domains

We have purified a protein that binds phosphatidylinositol 3,4,5-trisphosphate [PtdIns(3,4,5)P3] using beads bearing a PtdIns(3,4,5)P3 analogue. This protein, with a molecular mass of 43 kDa, was termed PtdIns(3,4,5)P3-binding protein. The partial amino acid sequences were determined and a full-length cDNA encoding the protein was isolated from bovine brain cDNA library. The clone harbored an open reading frame of 373 amino acids which contained one zinc finger motif similar to that of ADP-ribosylation-factor GTPase-activating protein and two pleckstrin homology domains. The entire sequence was 83% similar to centaurin alpha, another PtdIns(3,4,5)P3-binding protein. The protein bound PtdIns(3,4,5)P3 with a higher affinity than it did inositol 1,3,4,5-tetrakisphosphate, phosphatidylinositol 4,5-bisphosphate, phosphatidylinositol 3,4-bisphosphate, and phosphatidylinositol 3-phosphate suggesting that the binding to PtdIns(3,4,5)P3 was specific. The binding activity was weaker in the mutants with a point mutation in the conserved sequences in each pleckstrin homology domain. Introduction of both mutations abolished the activity. These results suggest that this new binding protein binds PtdIns(3,4,5)P3 through two pleckstrin domains present in the molecule.     

Expression of a gene cluster kaiABC as a circadian feedback process in cyanobacteria

Cyanobacteria are the simplest organisms known to have a circadian clock. A circadian clock gene cluster kaiABC was cloned from the cyanobacterium Synechococcus. Nineteen clock mutations were mapped to the three kai genes. Promoter activities upstream of the kaiA and kaiB genes showed circadian rhythms of expression, and both kaiA and kaiBC messenger RNAs displayed circadian cycling. Inactivation of any single kai gene abolished these rhythms and reduced kaiBC-promoter activity. Continuous kaiC overexpression repressed the kaiBC promoter, whereas kaiA overexpression enhanced it. Temporal kaiC overexpression reset the phase of the rhythms. Thus, a negative feedback control of kaiC expression by KaiC generates a circadian oscillation in cyanobacteria, and KaiA sustains the oscillation by enhancing kaiC expression.     

STM imaging of noble metal electrodes in solution under potentiostatic control

We have combined a three-electrode cell arrangement with a scanning tunnelling microscope (STM) to image the surfaces of polycrystalline noble metal electrodes under potentiostatic conditions. STM imaging was made in the potential range where a tip and the electrodes are ideally polarized. We have observed on a submicron scale that the electrochemically roughened Ag electrode surface relaxed over times of 40 min at ?0·16 V versus SCE in 0·1 m KCl. We have also imaged a dynamic process (formation and dissociation) of the submicron-scale reconstruction of the Au electrode subjected to electrochemical oxidation-reduction cycles. The results can be explained by the absorption of Cl^? ions and the surface diffusion of adatoms or clusters. STM imaging under potentiostatic control leads to the discovery of phenomena occurring at solid metal/electrolyte interfaces.     

Prediction of Concerted Sediment Flushing

A proprietary one-dimensional numerical model was developed for predicting the amounts of sediment flushed and deposited in the reservoirs in series, the bed evolutions, and variations of the suspended solids concentrations along a river during the concerted sediment flushing events. The model consists of a flow movement module and sediment transport module in which the bed material load is taken as sediment mixture. The nonuniform property of the bed material load is modeled by the introduction of a mixing layer, transition layer, and deposition strata. The model was calibrated on the basis of the field data at Dashidaira and Unazuki reservoirs on the Kurobe River in Japan. The calculated results are in good agreement with the measurements. For the reservoirs out of Japan, the Ashida and Michiue bed load formula used in the model should be verified or replaced by other formulas.     

Age-associated decrease in response of rat aquaporin-2 gene expression to dehydration

In biological movement systems, the level of muscular-articular links is responsible for assembling highly reliable, stable, and reproducible coordination patterns involving very many joints and muscles. Research shows that the important perceptual capabilities of this level arise from the bulk sensitivity of muscles and tendons, so-called effortful or dynamic touch, to the quantities of rotational dynamics that remain invariant (such as the inertia tensor) over variations in rotational forces and motions. The power laws characterizing this sensitivity point to underlying fractal (self-similar) processes. Other research shows that the hallmark ability of this level to produce repetitive interlimb coordinations can be addressed through a dynamics of coordination in which equations express the time-evolution of collective neuromuscular states. This research also suggests that the assembled rhythms exploit the unique blend of stability and variability characteristic of low-dimensional chaotic motion on strange attractors. In overview, research into the capabilities of the level of muscular-articular links highlights the importance of applying classical and modern (nonlinear) dynamics to understanding the assembly and perceptual control of biological movements.     

A case of systemic lupus erythematosus (SLE) successfully treated with mizoribine (Bredinin)

Mizoribine, a novel immunosuppressive agent developed in Japan, was administered as a monotherapy to a systemic lupus erythematosus (SLE) patient with the clinical symptoms and immunological abnormalities accompanying SLE showing marked improvement. The result of prolonged administration over 22 months in this case showed neither relapse nor side-effects. Reports have been made about mizoribine used concomitantly with steroids in the treatment of SLE; however, there have not been any reports of mizoribine as a monotherapy for SLE being effective. In this case, mizoribine (150 mg/day) was administered without steroids as a monotherapy on a outpatient basis since the patient's condition overall was relatively good and the serious complications of the heart, kidneys, and lungs that accompany SLE were not observed. The results of this treatment showed improvements in alopecia, arthritis, and systemic malaise from about the 4th week after the start of administration, and the clinical symptoms that accompany SLE had completely disappeared in the 8th week. Also, the immunological tests markedly improved. Four months after the start of administration the immunological abnormalities in the anti-DNA antibody, rheumatoid factor, and immune complex were completely corrected. This case showed dramatic improvement in the SLE clinical symptoms and immunological abnormalities with the mizoribine monotherapy as well as the potential for mizoribine monotherapy to maintain a state of remission over the long term.     

Fine structure of the dorsal lingual epithelium of the juvenile hawksbill turtle, Eretmochelys imbricata bissa

BACKGROUND: Various species of turtles are adapted to different environments, such as freshwater, seawater, and terrestrial habitats. Comparisons of histological and ultrastructural features of the tongue of the juvenile Hawksbill turtle, Eretmochelys imbricata bissa, with those of freshwater turtles should reveal some aspects of the relationship between the structure of the lingual epithelium and the environment. METHODS: The light microscope, scanning electron microscope and transmission electron microscope were used. RESULTS: Light microscopy revealed that the mucosal epithelium of the tongue was of the keratinized, stratified squamous type. Under the scanning electron microscope, no lingual papillae were visible on the dorsal surface of the tongue. Micropits and the thickening of cell margins were clearly seen on the surface of cells located on the outermost side. The transmission electron microscope revealed that the cells in the intermediate layer were gradually flattened from the basal side to the surface side, as were their nuclei. In the shallow intermediate layer, the cells were significantly flattened, and their nuclei were condensed or had disappeared. The cytoplasm contained keratohyalin granules, tonofibrils, free ribosomes, mitochondria, and rough endoplasmic reticulum. Numerous free ribosomes were attached to the surface of small keratohyalin granules. The cells of the keratinized layer were significantly flattened, and their nuclei had completely disappeared. Most of cytoplasm was filled with keratin fibers of high electron density. Keratin fibers of the shedding cells, which were located on the outermost side of the keratinized layer, appeared looser, and each fiber, which was somewhat thicker than the tonofibrils and tonofilaments, was clearly distinguishable. CONCLUSIONS: The lingual epithelium of the juvenile Hawksbill turtle differs significantly from that of the adult freshwater turtle, in spite of the similarity in gross morphology of the tongues of these species.