Discovery and pharmacological effects of a novel GPR142 antagonist

GPR142 is a G-protein-coupled receptor (GPCR), whose most potent and efficacious ligand has been reported as being the natural amino acid l-tryptophan. GPR142 is highly expressed in pancreatic β-cells and immune cells, suggesting the receptor may play a role in the pathogenesis and development of diabetes or inflammatory diseases. In a previous report, we developed GPR142 agonists as insulin secretagogues. In this report, we show the discovery of a selective, potent small-molecule GPR142 antagonist, CLP-3094, and its pharmacological characteristics. These data support targeting this receptor for the treatment of chronic inflammatory diseases.     

Isolation and Characterization of a Novel Single-Stranded RNA Virus Infecting the Bloom-Forming Diatom Rhizosolenia setigera

A novel single-stranded RNA (ssRNA) virus specifically infecting the bloom-forming diatom Rhizosolenia setigera (R. setigera RNA virus [RsRNAV]) was isolated from Ariake Sea, Japan. Viral replication occurred within the cytoplasm, and the virus particle was icosahedral, lacked a tail, and was 32 nm in diameter on average. The major nucleic acid extracted from the RsRNAV particles was an ssRNA molecule 11.2 kb in length, although smaller RNA molecules (0.6, 1.2, and 1.5 kb) were occasionally observed. The major structural proteins of RsRNAV were 41.5, 41.0, and 29.5 kDa. Inter- and intraspecies host specificity tests revealed that RsRNAV is not only species specific but also strain specific and that its intraspecies host specificity is diverse among virus clones. The latent period of RsRNAV was 2 days, and the burst sizes were 3,100 and 1,010 viruses per host cell when viruses were inoculated into the host culture at the exponential and stationary growth phases, respectively, at 15°C under a 12-h-12-h light-dark cycle of ca. 110 μmol of photons m⁻² s⁻¹ with cool white fluorescent illumination. To our knowledge, this is the first report describing the biological properties of a virus infecting a diatom. Further studies on RsRNAV will be helpful in understanding the ecological relationship between diatoms and viruses in nature.     

Temperature-controlled atmospheric-pressure plasma treatment induces protein uptake via clathrin-mediated endocytosis in tobacco cells

Previously, we developed a method that uses temperature-controlled atmospheric-pressure plasma to induce protein uptake in plant cells. In the present work, we examined the mechanism underlying such uptake of a fluorescent-tagged protein in tobacco leaf cells. Intact leaf tissue was irradiated with N₂ plasma generated by a multi-gas plasma jet and then exposed to the test protein (histidine-tagged superfolder green fluorescence protein fused to adenylate cyclase); fluorescence intensity was then monitored over time as an index of protein uptake. Confocal microscopy revealed that protein uptake potential was retained in the leaf tissue for at least 3 h after plasma treatment. Further examination indicated that the introduced protein reached a similar amount to that after overnight incubation at approximately 5 h after irradiation. Inhibitor experiments revealed that protein uptake was significantly suppressed compared with negative controls by pretreatment with sodium azide (inhibitor of adenosine triphosphate hydrolysis) or sucrose or brefeldin A (inhibitors of clathrin-mediated endocytosis) but not by pretreatment with genistein (inhibitor of caveolae/raft-mediated endocytosis) or cytochalasin D (inhibitor of micropinocytosis/phagocytosis), indicating that the N₂ plasma treatment induced protein transportation across the plant plasma membrane via clathrin-mediated endocytosis.     

Relationships between dynamics of red tide-causing raphidophycean flagellates and algicidal micro-organisms in the coastal sea of Japan

Temporal fluctuations of algicidal micro-organisms against the red tide causing raphidophycean flagellates Chattonella antiqua (Hada) Ono and Heterosigma akashiwo (Hada) Hada ex Hara et Chihara were investigated using the microplate most probable number (MPN) method in northern Hiroshima Bay and Harima-Nada, the Seto Inland Sea, in 1992 and 1993. In Har-ima-Nada, both flagellates appeared at low levels (< 1 cell mL^?1), and killer micro-organisms against the two flagellates (C-killer for C. antiqua and H-killer for H. akashiwo) also appeared at low densities (< 2 mL^?1). In northern Hiroshima Bay, C. antiqua cells were scarce (< 1 cell mL^?1), and C-killers occurred at a low level (≤ 3.4 mL^?1). Conversely, red tides of H. akashiwo occurred there in June of both years. The dynamics of H-killers revealed a close relationship with that of H. akashiwo populations. H-killers followed the increase of H. akashiwo cells, reached a maximum level after the beginning of decline of H. akashiwo, maintained a high level for at least 1 week after the crash of bloom, and then decreased. C-killers consistently remained at low densities during the period of H. akashiwo red tides in both 1992 and 1993. Hence, algicidal micro-organisms specifically associated with the occurrence and crash of H. akashiwo red tides, and presumably contributed to the rapid termination of the red tides in the coastal seas such as northern Hiroshima Bay.     

Potentiation of the activity of mouse liver-derived HBGF-1-like growth factor by heparin and dithiothreitol: evidence for the involvement of a plasma factor.

The potentiation of mouse liver derived heparin binding growth factors 1 and 2 (HBGF-1, HBGF-2) activity has been investigated. It was found that both heparin and various sulfhydryl reagents (such as dithiothreitol, DTT) markedly potentiated HBGF-1 activity, but not HBGF-2 activity. Further studies with HBGF-1 indicated that the growth factor would interact with a plasma factor, in a temperature-dependent manner, to become inactive, and that sulfhydryl reagents would reverse this inactivation. Inactivation would not occur either in the presence of heparin or DTT, indicating that heparin and DTT can protect the growth factor from plasma inactivation. When assayed in the absence of plasma, both heparin and DTT were required to reactivate plasma inactivated HBGF-1-ML. A model is presented to explain these data. This model predicts that either DTT or heparin can block the plasma induced inactivation process, but that once inactivation has occurred only sulfhydryl reagents can restore activity. Furthermore, heparin is thought to activate growth factor activity in the absence of plasma by blocking non-productive growth factor binding to the extracellular matrix. The identification of a plasma inactivating factor for mouse liver derived HBGF-1 has important implications for understanding the regulation of extracellular growth factor activity.     

Regional Distribution and Production Rate of 3-Methoxy-4-Hydroxyphenylethyleneglycol Sulphate (MHPG-SO4) in Rat Brain

The levels of noradrenaline (NA) and 3-methoxy-4-hydroxyphen-ylethyleneglycol sulphate (MHPG-SO₄) in 15 brain regions showed a parallel distribution in male Wistar rats. The differences in regional distribution of MHPG-SO₄ were similar to those in the rate of NA turnover reported by other investigators. The accumulation rates of MHPG-SO₄ during 45 and 90 min after probenecid injection significantly correlated to the steady state levels of MHPG-SO₄ in nine regions studied. With the results, the regional levels of MHPG-SO, either in untreated or in probenecid-treated rats, are considered to be a useful index of NA turnover.     

Attenuated response of the serum triglyceride concentration to ingestion of a chocolate containing polydextrose and lactitol in place of sugar

We examined the effects of ingesting a non-sugar chocolate containing polydextrose and lactitol in place of sucrose and lactose on the concentrations of plasma glucose and serum insulin and triglyceride in humans. A regular chocolate was used as the control. A crossover study was employed, and the subjects each ingested 46 g of the control or non-sugar chocolate in the experiments. Alterations in the blood components were monitored for a period of 150 min after ingestion. The control chocolate elevated the concentrations of plasma glucose and serum insulin, with the peak occurring 30 min after ingestion, but the non-sugar chocolate had a very minor effect. The serum triglyceride concentration gradually increased after ingesting the control chocolate, but was only slightly elevated 150 min after ingesting the non-sugar chocolate. An animal study also showed an attenuated response of serum triglyceride to the administration of a fat emulsion containing polydextrose and lactitol, suggesting that the triglyceride transit through the gut was promoted by these compounds. These results suggest that, compared to regular chocolate, fat absorption in the gut was less after ingesting the non-sugar chocolate, presumably resulting in less effect on body fat deposition.