Ionic mechanism of 5-hydroxytryptamine induced hyperpolarization and inhibitory junctional potential in body wall muscle cells of Hirudo medicinalis

Five-hydroxy tryptamine (5-HT) causes a hyperpolarization and increased conductance of the leech body wall muscle cell membrane. If 5-HT is applied in the absence of the Cl^?ion, the response appears as a depolarization, whereas if 5-HT is applied in the absence of the K⁺ion, the response is a hyperpolarization. In both cases, the conductance of the muscle cell membrane is increased. Stimulation of the peripheral nerve to the body wall muscle produces a complex junctional potential in muscle cells. Exposing the muscle to d-tubocurarine (d-TC) eliminates the excitatory component (EJP) of the complex potential. The inhibitory potential (IJP) that remains has an equilibrium potential at approximately 65 m V. Furthermore, this IJP appears as a depolarization when the nerve is stimulated in the presence of d-TC and low CL^?, whereas this is not the case if the nerve is stimulated in the presence of d-TC and low K⁺. The drugs BOL-148 and cyproheptadine block the IJP's in the body wall muscle. These data are interpreted as indicating that 5'HT acts on leech body wall muscle cells by increasing the conductance to the Cl^?ion and that the IJP's caused by nerve stimulation are probably the result of 5-HT release at nerve terminals. As a final point, it has been shown that the inhibition by 5-HT of the spontaneous EJP's that occur on the leech body wall muscle results from an inhibition of central neurons and not from any direct effect on the muscle cell or on peripheral synapses.     

Isolated corticotrophin-deficiency found through alcohol-induced hypoglycemic coma.

A case of hypoglycemic coma after alcohol ingestion was observed in a chronic alcoholic. Upon close examination isolated corticotrophin-deficiency was found. It is suggested that ethanol-induced hypoglycemia may be consistent with dysfunction of mitochondria in hepatic cells and that there may be disorder of the hypothalamus in the chronic drinker.     

Dystrophin in rod spherules; submembranous dense regions facing bipolar cell processes

 It is known that the retina contains the protein dystrophin in the ribbon synapse, but the ultrastructural analysis is not yet fully elucidated. Our previous study reported that dystrophin is localized under the rod cell membranes in rat retinas. In the present study, we have investigated the relationship between dystrophin-rich regions of rod cell membranes and other neuronal processes in mouse retinas with a monoclonal antibody raised against the human dystrophin C-terminus. Immunoblotting, immunofluorescence stainings, and immunoelectron microscopy were employed. Immunoblotting analysis indicated that mouse retinas possessed some of the dystrophin isoforms of approximately 260 kDa, 140 kDa, and 70 kDa molecular weight. Confocal images showed a punctate appearance in the outer plexiform layer, as previously described. Immunoelectron microscopy showed that dystrophin immunoreactive products were always observed at submembranous dense regions of the rod spherule abutting bipolar processes. These results suggest that retinal dystrophin may be closely involved in signal transmission from rods to bipolar cells. Accepted: 7 May 1997     

Stimulation of thiamine diphosphate activity by ascorbic acid in rat brain microsomes

The effect of ascorbic acid on microsomal thiamine diphosphate activity in rat brain was examined. Ascorbic acid at 0.02–0.1 mM increased the thiamine diphosphate activity by 20–600% and produced a significant amount of lipid peroxide, which was measured with thiobarbiturate under the same conditions as the enzyme. A lag period of about 10 min was observed in the process of stimulation of enzyme activity by ascorbic acid. The stimulation of enzyme activity and the lipid peroxidation induced by ascorbic acid were blocked by metal-binding compounds (EDTA, α,α′-dipyridyl, o-phenanthroline) and an antioxidant (N,N′-diphenyl p-phenylenediamine). GSH significantly enhanced the stimulation of enzyme activity and formation of lipid peroxide by 0.02–0.05 mM ascorbic acid. The effect of GSH was due in part to maintenance of the concentration of ascorbic acid in the medium, since GSH could convert dehydroascorbic acid, an oxidized form of ascorbic acid, to ascorbic acid.     

The fine structure of ependymal cells part II: An electron microscopic study of the soft-shelled turtle paraventricular organ,with special reference to the fine structure of ependymal cells and so-called albuminous substance

Summary The present study deals with the electron microscopic observations on the softshelled turtle paraventricular organ, with special reference to the relationship of the ependymal cells and the so-called albuminous substances. It is shown that the so-called albuminous substances consist of the tips of neuronal processes extending into the ventricular lumen. They probably arise from the nerve cells lying within the hypendymal or the underlying tissue. The ependymal cells of the PVO themselves are basically similar in structure to those of any other animal.The processes observed contain two types of vesicles, namely: the clear vesicle, 500 to 1600 Å in diameter, and the cored vesicle, measuring 600 to 1500 Å in diameter, which has a distinct membrane enclosing an extremely dense core of variable sizes. The functional significance of these vesicles is discussed in relation to that of inclusions in the neurosecretory and the autonomic nerve fibers in the hypothalamus.The findings indicate that in the terminal endings of the processes a production or formation of vesicles might occur and that these vesicles might be discharged into the cerebrospinal fluid by microapocrine secretion.The author's grateful thanks are due to Prof. E. Yamada for his continuously kind guidances and due to Prof. T. Sakurai for his constant encouragement.     

Microflow system promotes acetaminophen crystal nucleation

It is known that interfaces have various impacts on crystallization from a solution. Here, we describe crystallization of acetaminophen using a microflow channel, in which two liquids meet and form a liquid–liquid interface due to laminar flow, resulting in uniform mixing of solvents on the molecular scale. In the anti‐solvent method, the microflow mixing promoted the crystallization more than bulk mixing. Furthermore, increased flow rate encouraged crystal formation, and a metastable form appeared under a certain flow condition. This means that interface management by the microchannel could be a beneficial tool for crystallization and polymorph control.     

Enhancing coral larval supply and seedling production using a special bundle collection system “coral larval cradle” for large‐scale coral restoration

Larval recruitment is essential for sustaining coral communities and a fundamental tool in some interventions for reef restoration. To improve larval supply and post‐settlement survival in sexually assisted coral restoration efforts, an integrated in situ collector system, the larval cradle, was designed to collect spawned gametes then culture the resulting larvae until settled on artificial substrates. The final design of the larval cradle was cylindrical, a nylon mesh structure with a volume of 9 m³, suspended in the sea and extending vertically toward the seabed. We found three key design features that improved the efficiency of the apparatus: (1) an open area of sea surface and mesh size of less than 100 μm produced high fertilization and optimal survival (>90%), (2) a special skirt‐shaped net (3 m in diameter) with a connection hose for attaching the cradle to collect bundles from many adult colonies over a wide area and at various depths, and (3) adding short square tube pieces, called square hollow sections, as a substrate for enhancing larval settlement and survival, to a larval cradle at 4 days after spawning was optimal for uniform settlement. This system allowed not only the collection of several million eggs, but also subsequent production of several thousand settled juvenile corals, without land facilities. Our design achieved several hundred times higher survival for early life stages of Acropora tenuis compared to nature.     

New clade of silicified bolidophytes that belong to Triparma (Bolidophyceae,Stramenopiles)

The small phytoplankton genus Triparma belongs to the class Bolidophyceae and contains two distinct forms: silicified species and naked flagellated species (formerly Bolidomonas). Recent studies showed that four silicified species/strains (Triparma laevis f. inornata, T. laevis f. longispina, T. strigata, and T. aff. verrucosa) belong to a single clade that is paraphyletic, because it also contains an unclassified flagellated strain, and is sister to a flagellated species, T. eleuthera. In this study, we isolated and characterized two new strains of silicified species to test the phylogenetic unity of silicified bolidophytes. The isolates were identified as T. retinervis strains because they possessed fine areolation on the cell wall. 18S rDNA and rbcL phylogenetic analyses demonstrated that T. retinervis formed a new silicified clade that is sister to the flagellated species T. pacifica. This reveals that there are at least two distinct clades including both silicified and flagellated Triparma species.