Host plant use for oviposition by Trigonotylus caelestialium (Hemiptera: Miridae) and Stenotus rubrovittatus (Hemiptera: Miridae)

The main hosts and sites of oviposition for the two bugs, Trigonotylus caelestialium (Kirkaldy) (Hemiptera: Miridae) and Stenotus rubrovittatus (Matsumura) (Hemiptera: Miridae), that cause pecky rice were investigated in 24 poaceous plants. Nymphs of T. caelestialium emerged from both spikelets and leaf sheaths, while nymphs of S. rubrovittatus emerged almost exclusively from spikelets. Suitable plants for oviposition by T. caelestialium are Lolium multiflorum, Digitaria violascens and Hordeum murinum, while Poa annua, Anthoxanthum odoratum, Alopecurus aequalis and D. violascens were preferentially used by S. rubrovittatus. There was a greater difference in the number of nymphs emerging from different plants for S. rubrovittatus than for T. caelestialium. This difference may be because T. caelestialium can oviposit on leaf sheaths if the spikelets are not suitable for oviposition, whereas S. rubrovittatus only oviposits on spikelets. Although both bugs oviposited on spikelets, the internal oviposition sites were different. In D. ciliaris, T. caelestialium laid all eggs between the lemma of the first floret and the second floret, whereas S. rubrovittatus laid eggs almost exclusively inside the second floret. In contrast, in P. annua, T. caelestialium laid all eggs inside the florets, whereas S. rubrovittatus laid eggs both between and inside the florets.     

Prolactin inhibits osteoclastic activity in the goldfish scale: a novel direct action of prolactin in teleosts

In teleosts, prolactin is involved in calcium regulation, but its role in scale/bone metabolism is unclear. Using the in-vitro system with goldfish scales developed recently, we explored the effects of teleost prolactin, growth hormone, and somatolactin on osteoclasts and osteoblasts. Addition of prolactin at concentrations of 0.01-100 ng/ml reduced osteoclastic activity, partly via osteoclast apoptosis, after 6-18 h incubation. Conversely, growth hormone and somatolactin at a concentration of 100 ng/ml increased osteoclastic activity after 18 h incubation, indicating the specificity of the inhibitory effect of prolactin on osteoclastic activity. On the other hand, these three hormones promoted osteoblastic activity at concentrations of 10-100 ng/ml. The results from this study are the first demonstration of direct effects of prolactin on scale/bone metabolism and osteoclastic activity in a teleost.     

Metabolism of N-methylcarbamate insecticides by mosquito larval enzyme system requiring NADPH2

A mosquito larval enzyme system requiring NADPH₂ as cofactor for metabolism of the N-methylcarbamate insecticides propoxur, carbaryl, carbofuran and aldicarb has been demonstrated. Freshly prepared homogenate catalyzes various oxidative reactions involving initial hydroxylation of benzene, naphthalene, and furan rings, hydroxylation of N-methyl group, O-dealkylation, N-dealkylation and thioether oxidation to sulfoxides and sulfones. The reactions are primarily oxidative; however, in certain cases, trace amounts of hydrolysis products are also obtained. Inhibitors of mixed function oxidases and synergists inhibit the metabolism of propoxur. Mosquito larval mixed function oxidases appear to be different from those of other insects, in respect to enzyme stability, presence of endogenous inhibitors, and certain requirements for incubation conditions.

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Zusammenfassung Für die Umwandlung der N-Methylcarbamat-Insektizide Propoxur, Carbaryl, Carbofuran und Aldicarb wird in Mückenlarven ein NADPH₂-benötigendes Enzymsystem nachgewiesen. Frisch hergestellte Homogenate katalysieren verschiedene oxydative Reaktionen wie die Hydroxylierung von Benzol, Naphtalin und Furan-Ringen, die Hydroxylierung von N-Methyl-Gruppen, die O-dealkylierung, die N-dealkylierung und Thioäther-Oxydation zu Sulfoxyden und Sulfonen. Die Reaktionen sind primär oxydativ; jedoch werden in bestimmten Fällen auch Spuren von Hydrolyse-Produkten erhalten. Inhibitoren der Oxydasen gemischter Funktion und Synergisten verhindern den Abbau von Propoxur. Oxydasen gemischter Funktion der Mückenlarven scheinen von denen anderer Insekten im Hinblick auf die Enzym-Stabilität, die Anwesenheit endogener Inhibitoren und gewisse Anforderungen an die Inkubationsbedingungen verschieden zu sein.

     

The 'O-acyl isopeptide method' for the synthesis of difficult sequence-containing peptides: application to the synthesis of Alzheimer's disease-related amyloid beta peptide (Abeta) 1-42.

An efficient 'O-acyl isopeptide method' for the synthesis of difficult sequence-containing peptides was applied successfully to the synthesis of amyloid beta peptide (Abeta) 1-42 via a water-soluble O-acyl isopeptide of Abeta1-42, i.e. '26-O-acyl isoAbeta1-42' (6). This paper describes the detailed synthesis of Abeta1-42 focusing on the importance of resin selection and the analysis of side reactions in the O-acyl isopeptide method. Protected '26-O-acyl isoAbeta1-42' peptide resin was synthesized using 2-chlorotrityl chloride resin with minimum side reactions in comparison with other resins and deprotected crude 26-O-acyl isoAbeta1-42 was easily purified by HPLC due to its relatively good purity and narrow elution with reasonable water solubility. This suggests that only one insertion of the isopeptide structure into the sequence of the 42-residue peptide can suppress the unfavourable nature of its difficult sequence. The migration of O-acyl isopeptide to intact Abeta1-42 under physiological conditions (pH 7.4) via O--N intramolecular acyl migration reaction was very rapid and no other by-product formation was observed while 6 was stable under storage conditions. These results concluded that our strategy not only overcomes the solubility problem in the synthesis of Abeta1-42 and can provide intact Abeta1-42 efficiently, but is also applicable in the synthesis of large difficult sequence-containing peptides at least up to 50 amino acids. This synthesis method would provide a biological evaluation system in Alzheimer's disease research, in which 26-O-acyl isoAbeta1-42 can be stored in a solubilized form before use and then rapidly produces intact Abeta1-42 in situ during biological experiments.     

Identification of neurite outgrowth-promoting domains of neuroglycan C, a brain-specific chondroitin sulfate proteoglycan, and involvement of phosphatidylinositol 3-kinase and protein kinase C signaling pathways in neuritogenesis

Neuroglycan C (NGC) is a transmembrane-type chondroitin sulfate proteoglycan that is exclusively expressed in the central nervous system. We report that the recombinant ectodomain of NGC core protein enhances neurite outgrowth from rat neocortical neurons in culture. Both protein kinase C (PKC) inhibitors and phosphatidylinositol 3-kinase (PI3K) inhibitors attenuated the NGC-mediated neurite outgrowth in a dose-dependent manner, suggesting that NGC promotes neurite outgrowth via PI3K and PKC pathways. The active sites of NGC for neurite outgrowth existed in the epidermal growth factor (EGF)-like domain and acidic amino acid (AA)-domain of the NGC ectodomain. The EGF-domain caused cells to extend preferentially one neurite from a soma, whereas the AA-domain caused several neurites to develop. The EGF-domain also enhanced neurite outgrowth from GABA-positive neurons, but the AA-domain did not. These results suggest that the EGF-domain and AA-domain have distinct functions in terms of neuritogenesis. From these findings, NGC can be considered to be involved in neuritogenesis in the developing central nervous system.     

The reaction of H(2)S with oxidized thiols: generation of persulfides and implications to H(2)S biology

Hydrogen sulfide is an endogenously generated molecule with many reported physiological functions. Although several biological targets have been proposed, the biochemical mechanisms by which it elicits activity are not established. Thus, in an effort to begin to delineate the fundamental biological chemistry of H₂S, we have examined the reaction of H₂S with oxidized thiols and thiol proteins in order to determine whether persulfide formation occurs, is stable and how this may affect protein function. We have found that persulfides are easily generated, relatively stable and can alter enzyme activity. Moreover, we have begun to develop methodology for in situ generation of persulfides to facilitate further study of this potentially important species.     

4‐Fluorophenyl 3‐nitro‐2‐pyridinesulfenate as a practical protecting agent for amino acids

We report a new protecting agent ( 1 , Npys‐OPh(pF)) for 3‐nitro‐2‐pyridine (Npy) sulfenylation of amino, hydroxy, and thiol functional groups. Several Npys phenoxides were synthesized from Npys chloride (Npys‐Cl) and phenols in the presence of base in 1‐step reaction, and their ability for Npy‐sulfenylation was evaluated. As a result, 1 was selected as a new Npy‐sulfenylation agent with advantages including improved physicochemical stability, more controllable reactivity, and easier handling than the conventional protecting agent Npys‐Cl.