Arnoglossus macrolophus Alcock (Pleuronectiformes: Bothidae); a valid species distinct fromA. tapeinosomus (Bleeker)

The holotype of a bothid flounder,Arnoglossus tapeinosomus (Bleeker, 1866), was re-examined and found to bear none of the diagnostic characters ascribed by many authors to the species. In addition, the shape of the prevomer was clearly different between the holotype and 18 specimens supposedly“A. tapeinosomus.” A. macrolophus Alcock, 1889, which was synonymized underA. tapeinosomus by Weber and de Beaufort (1929), is considered as a valid replacement name for“A. tapeinosomus,” because of the elongated anterior rays in the dorsal fin and a large, dark spot on the posterior dorsal and anal fin bases.A. tapeinosomus is redescribed from the holotype.     

Efficient production of IGG human monoclonal antibodies by lymphocytes stimulated by lipopolysaccharide,pokeweed mitogen,and interleukin 4

Summary Extensive screening of the mitogens lipopolysaccharide (LPS), pokeweed mitogen (PWM), andStaphylococcus aureus Cowan I (SAC I), alone and in combination and with and without interleukin (IL) was performed forin vitro activation of regional lymph node lymphocytes from lung cancer patients for the production of human IgG, IgM, and IgA. As assessed by electrofusion of the lymphocytes following their exposure to these agents with mouse myeloma cells and incubation of the fused hybridoma, a remarkable stimulatory effect was shown by LPS and particularly by LPS plus IL-4, which was substantially greater than that of either SAC I or PWM with or without various IL. Optimization studies indicated that the addition of PWM to LPS and IL-4 in the culture medium further stimulated the human antibody (Ab) production, and that the optimal formulation for stimulations of human IgG production was a culture medium containing 20 μg/ml of LPS, 1/500 of PWM, and 100 u/ml of IL-4.     

Characterization of a Dopamine-Releasing Action of 6R-l-erythro-Tetrahydrobiopterin: Comparison with a 6S-Form

Abstract: 6R-l -erythro-Tetrahydrobiopterin (6R-BH₄) is a cofactor for aromatic l -amino acid hydroxylases and nitric oxide synthase. Recently, we have reported that independently of its cofactor activities, 6R-BH₄ acts from the outside of neurons in the brain to enhance the release of monoamine neurotransmitters such as dopamine. To characterize the pharmacological properties of the action, we examined the effects of 6S-BH₄, a diastereoisomer of 6R-BH₄, on dopamine release in the rat striatum by using brain microdialysis and compared its effects with those of 6R-BH₄. Perfusion of 6S-BH₄ or 6R-BH₄ through the dialysis probe increased extracellular dopamine levels (an index of in vivo dopamine release) concentration dependently; the maximal increase by 6S-BH₄, was one-sixth of that by 6R-BH₄. 6S-BH₄ increased extracellular DOPA levels in the presence of NSD 1015, an inhibitor of aromatic l -amino acid decarboxylase (an index of in vivo tyrosine hydroxylase activity), to an extent similar to the increase induced by 6R-BH₄. The increase in the DOPA levels induced by either of the pteridines was abolished after pretreatment of rats with α-methyl-p-tyrosine (an inhibitor of tyrosine hydroxylase). Under the same conditions, the 6S-BH₄-induced dopamine release was abolished, but most of the 6R-BH₄-induced increase persisted. Coadministration of 6S-BH₄ with 6R-BH₄ inhibited the increase in dopamine release induced by 6R-BH₄ alone. These results show that 6R-BH₄ stimulates dopamine release by acting at the specific recognition site on the neuronal membrane, and that 6S-BH₄ acts as an antagonist of 6R-BH₄ at this site, although it has cofactor activities.     

Differential Effects of Hypoxia on Ligand Binding Properties of Nicotinic and Muscarinic Acetylcholine Receptors on Cultured Bovine Adrenal Chromaffin Cells

Abstract: Hypoxia is known to disturb neuronal signal transmission at the synapse. Presynaptically, hypoxia is reported to suppress the release of neurotransmitters, but its postsynaptic effects, especially on the function of neurotransmitter receptors, have not yet been elucidated. To clarify the postsynaptic effects, we used cultured bovine adrenal chromaffin cells as a model of postsynaptic neurons and examined specific binding of l -[³H]nicotine (an agonist for nicotinic acetylcholine receptors: nAChRs) and ²²Na⁺ flux under control and hypoxic conditions. Experiments were performed in media preequilibrated with a gas mixture of either 21% O₂/79% N₂ (control) or 100% N₂ (hypoxia). Scatchard analysis of the specific binding to the cells revealed that the K_D under hypoxic conditions was twice as large as that under control conditions, whereas the B _max was unchanged. When the specific [³H]nicotine binding was kinetically analyzed, the association constant ( k ₁) but not the dissociation constant ( k ₋₁) was decreased to 40% of the control value by hypoxia. When the binding assay was performed using the membrane fraction, these changes were not observed. Nicotine-evoked ²²Na⁺ flux into the cells was suppressed by hypoxia. In contrast, specific [³H]quinuclidinyl benzilate binding to the intact cells was unaffected by hypoxia. These results demonstrate that hypoxia specifically suppresses the function of nAChRs (and hence, neuronal signal transmission through nAChRs), primarily by acting intracellularly.     

Production of d-Tagatose from Dulcitol by Arthrobacter globiformis

A process for the bacterial oxidation of dulcitol to d-tagatose has been developed. The strain Arthrobacter globiformis ST48 used in this fermentation was isolated from soil. The yield of d-tagatose accumulated in the medium from dulcitol was as high as 85%. About 14 g of d-tagatose crystals was isolated from 1 liter of 2% dulcitol medium.     

Development of the axon cap neuropil of the Mauthner cell in the goldfish

Summary Development of the axon cap neuropil of the Mauthner neuron in post-hatching larval goldfish brains was observed electron-microscopically. The axonal initial segment of newly hatched (day-4) larvae is completely covered with synaptic terminals containing clear spherical synaptic vesicles. Profiles of thin terminal axons, the spiral fibers, containing similar synaptic vesicles, rapidly increase in number around the initial segment and form glomerular neuropil similar to the central core of the adult axon cap by day 7. Three types of synapses are formed in the core neuropil. Bouton-type synapses contacting the initial segment are most abundant in day-4 to-14 larvae; they decrease thereafter and are rare on the distal half of the initial segment of day-40 larvae. Asymmetric axo-axonic synapses are commonly observed between spiral fibers in the core neuropil of day-7 to -19 larvae, but become fewer by day 40. Unique symmetrical axo-axonic synapses showing accumulation of synaptic vesicles on either side of apposed membrane thickenings first appear in day-14 core neuropil, gradually increase in number, and become the predominant type in day-40 core neuropil. Thick myelinated axons, which lose their myelin sheaths in the glial cap cell layer, start to penetrate into the axon cap on day 10. They gradually increase in number and form the peripheral part of the axon cap together with the cap dendrites, which finally grow into the axon cap from the axon hillock region of the Mauthner cell by day 40.     

Methylation analysis of extracellular polysaccharides from suspension-cultured cells of Nicotiana tabacum

The soluble extracellular polysaccharides (ECP) of suspension-cultured tobacco cells were fractionated by DEAE-Sephadex CC into seven sub-fractions. Su     

α-Methylene-γ-aminobutyric acid from Mycena pura

α-Methylene-γ-aminobutyric acid was isolated and characterized from fruit bodies of Mycena pura. It was the decarboxylation product of l-γ-methyleneglutamic acid by l-glutamic acid decarboxylase.