Synthesis of heterotelechelic poly(ethylene glycol) derivatives having alpha-benzaldehyde and omega-pyridyl disulfide groups by ring opening polymerization of ethylene oxide using 4-(diethoxymethyl)benzyl alkoxide as a novel initiator

New heterotelechelic PEG-containing benzaldehyde and 2-pyridyldithio endgroup (CHO-Bz-PEG-SSpyl) was synthesized with high efficiency and high selectivity. An alpha-benzylacetal-omega-methansulfonyl PEG was prepared as the first step to CHO-Bz-PEG-SSpyl through the ring-opening polymerization of ethylene oxide (EO) initiated by potassium 4-(diethoxymethyl)benzyl alkoxide (PDA), followed by the successive conversion of the end-alkoxide group to a methanesulfonyl group and then to dithiocarbonate derivative. Further, deprotection of the dithiocarbonate derivative and subsequent conversion to the 2-pyridyldithio group at the omega-end was successfully performed through a one-step reaction to form alpha-benzylacetal-omega-2-pyridyldithio PEG (aceBz-PEG-SSpyl). The aceBz-PEG-SSpyl was then treated with an aqueous HCl solution (pH 5.0) to generate the benzaldehyde group at the alpha-end. Molecular functionalities of the benzaldehyde and the 2-pyridyldithio end group of the heterotelechelic PEG (CHO-Bz-PEG-SSpyl) thus prepared were characterized by (1)H and (13)C NMR, showing that the reaction proceeded almost quantitatively. The benzaldehyde end group is available to conjugate various ligands having a primary amino group by forming the pH-sensitive imine linkage (-N=CHC(6)H(4)-).     

Development of cholinergic chronotropic control in chick (Gallus gallus domesticus) embryos

In chick (Gallus gallus domesticus) embryos, instantaneous heart rate begins to fluctuate with the appearance of rapid, transient decelerations at around the end of the second week of incubation. Previously, it was shown that instantaneous heart rate decelerations were eliminated by administration of atropine and concurrently heart rate baseline was elevated in late embryos. Because the previous study lacked statistical treatment and there has been recent controversy over the development of tonic vagal control of the heart, we reexamine the hypothesis that transient decelerations of instantaneous heart rate are mediated by vagus nerve and the vagal tone begins to appear at around the end of the second week of incubation. Atropine administration tests were conducted for sixty-seven 11- to 14-day-old and 18-day-old embryos in total. Heart rate decelerations appeared sporadically in three out of ten 12-day-old embryos, but the difference of mode heart rate before and after administration of atropine was not significant. Seven out of nine 13-day-old embryos and all nine 14-day-old embryos showed heart rate decelerations and the difference of mode heart rate before and after atropine administration was significant. In late (18-day-old) embryos, magnitude and frequency of instantaneous heart rate decelerations further increased with additional appearance of transient, irregular accelerations. Administration of varying doses of atropine completely eliminated the heart rate decelerations and elevated the heart rate baseline more markedly than in young embryos, indicating the maturation of vagal tone late in incubation.     

A functional link between Disrupted-In-Schizophrenia 1 and the eukaryotic translation initiation factor 3

Disrupted-In-Schizophrenia 1 (DISC1) was identified as a candidate gene for schizophrenia. DISC1 is disrupted by a balanced t(1;11)(q42.1;q14.3) translocation segregating with schizophrenia and related psychiatric illness in a large Scottish family. Here, we show that DISC1 interacts via its globular domain with the p40 subunit of the eukaryotic translation initiation factor 3. Furthermore, we found that overexpression of DISC1 in SH-SY5Y cells induces the assembly of eIF3- and TIA-1-positive stress granules (SGs), discrete cytoplasmic granules formed in response to environmental stresses. Our findings suggest that DISC1 may function as a translational regulator and may be involved in stress response.     

The mammalian homolog of the Drosophila discs large tumor suppressor protein up-regulates expression of the ELR+ CXC chemokine Scyb5

The mammalian homolog of the Drosophila discs large tumor suppressor protein Dlg functions as a scaffolding protein that facilitates the transmission of diverse signals. In the present study, we attempted to identify the downstream target genes of Dlg, and found that Dlg up-regulates expression of the ELR+ CXC chemokine Scyb5, which has been implicated in the immune system. Our finding suggests that Scyb5 may play an important role in the tumor suppressor function of Dlg.     

Microsite variation in light availability and photosynthesis in a cool-temperate deciduous broadleaf forest in central Japan

An empirical light simulation model was applied to estimate stand scale photosynthesis in a deciduous broadleaved forest in central Japan. Based on diurnal courses of photosynthetically active photon flux density (PPFD), we characterized the components of incoming light within the forest canopy, and found that the instantaneous relative PPFD (PPFD under the canopy relative to that above the canopy) under diffuse light condition was a reliable estimator of the intensity and duration of PPFD. We calculated the daily photosynthesis (A_day) for each PPFD class using photosynthesis–light response curves. Model simulated A_day were corroborated with the estimates obtained from the nearby CO₂ flux tower. The result demonstrated the potential of the light simulation model. The light use efficiency of two dominant species, Betula ermanii as overstory and Sasa senanensis as understory species, were then evaluated. At the forest understory, PPFD under 50 mol m^–2 s^–1 contributed to 77% of the sunshine duration on a completely clear day. Therefore, a higher apparent quantum yield for S. senanensis enhanced the utilization of low PPFD for photosynthesis. On the other hand, at the upper forest canopies, B. ermanii with a higher light-saturated photosynthetic rate used high PPFD efficiently. Consequently, potential of daily net photosynthesis for both B. ermanii and S. senanensis was high under each light condition. Such interspecific difference in the patterns of light utilization was suggested as one of factors allowing coexistence of the two species in the study forest.     

Avidin expressed in transgenic rice confers resistance to the stored-product insect pests Tribolium confusum and Sitotroga cerealella

Rice (Oryza sativa var. Nipponbare) was transformed with an artificial avidin gene. The features of this construct are as follows: (1) a signal peptide sequence derived from barley alpha amylase was added at the N-terminal region, (2) codon usage of the gene was optimized for rice, and (3) the gene was driven by rice glutelin GluB-1, an endosperm-specific promoter. Avidin was produced in the grain of the transgenic rice but not in the leaves. The concentration of avidin in the kernels was about 1,800 ppm. All larvae of the confused flour beetle (Tribolium confusum) and Angoumois grain moth (Sitotroga cerealella) died when fed transgenic avidin rice powder or kernels, respectively, whereas most of the test insects developed into adults when they were fed a nontransgenic rice control diet. Avidin extracted from the transgenic rice kernel lost most biotin-binding activity after 5 min heating at 95 degrees C.     

Generation of high-affinity antibody against T cell-dependent antigen in the Ganp gene-transgenic mouse

Generation of high-affinity Ab is impaired in mice lacking germinal center-associated DNA primase (GANP) in B cells. In this study, we examined the effect of its overexpression in ganp transgenic C57BL/6 mice (Ganp(Tg)). Ganp(Tg) displayed normal phenotype in B cell development, serum Ig levels, and responses against T cell-independent Ag; however, it generated the Ab with much higher affinity against nitrophenyl-chicken gammaglobulin in comparison with C57BL/6. To further examine the affinity increase, we established hybridomas producing high-affinity mAbs and compared their affinities using BIAcore. C57BL/6 generated high-affinity anti-nitrophenyl mAbs (K(D) approximately 2.50 x 10(-7) M) of IgG1/lambda1 and contained the V(H)186.2 region with W33L mutation. Ganp(Tg) generated much higher affinity (K(D) > 1.57 x 10(-9) M) by usage of V(H)186.2 as well as noncanonical V(H)7183 regions. Ganp(Tg) also generated exceptionally high-affinity anti-HIV-1 (V3 peptide) mAbs (K(D) > 9.90 x 10(-11) M) with neutralizing activity. These results demonstrated that GANP is involved in V region alteration generating high-affinity Ab.     

Synthesis and biological activities of novel aryl indole-2-carboxylic acid analogs as PPARgamma partial agonists

A series of novel aryl indole-2-carboxylic acids has been identified as potent selective PPARgamma modulators. Their chemical synthesis and in vitro activities are discussed. Compound 5 was selected for in vivo testing in the db/db mouse model of type 2 diabetes and resulted in reduction of hyperglycemia at comparable plasma exposure when compared to rosiglitazone.     

Synthesis and biological activity of sulphostin analogues, novel dipeptidyl peptidase IV inhibitors

The structure of sulphostin (1), a novel dipeptidyl peptidase IV (DPP-IV) inhibitor, is consisted of three key functional groups, including a characteristic amino(sulfoamino)phosphinyl group, on a piperidine ring. To examine the relationship between its structure and the inhibitory activity against DPP-IV, various analogues were synthesized and their activities were investigated. These results indicated that all of the functional groups on the piperidine ring were crucial to the DPP-IV inhibitory activity of sulphostin, and that the sulfonic acid group, which constructed the amino(sulfoamino)phosphinyl group, contributed to the stability of the compound. Moreover, those functional groups should be adjoined on the piperidine ring for the inhibitory activity. The size of the nitrogen-containing heterocyclic ring including piperidine appeared to scarcely affect the activity. In the present study, the sulfonic acid-deficient five-membered ring analogue 27a showed the strongest inhibitory activity (IC50=11 nM).     

GSH inhibits trypsinization of the C-terminal half of human MRP1

MRP1 is a 190-kDa membrane glycoprotein that confers multidrug resistance to tumor cells. The accumulated evidence has proved that GSH interacts with MRP1 and stimulates drug transport. However, the mechanism of GSH-dependent drug transport by MRP1 remains unclear. In this study, we used limited tryptic digestion of MRP1 in isolated membrane vesicles, in the presence and absence of GSH, to investigate the influence of GSH on MRP1 conformation. We found that GSH inhibited the generation of an approximately 35-kDa C-terminal tryptic fragment (including a C-terminal His tag) termed C2 from MRP1. This effect of GSH was not because of direct inhibition of trypsin activity, and agosterol A enhanced the inhibitory effect of GSH. The main cleavage site in MRP1 for the generation of the C2 fragment by trypsin resided between TMD2 and NBD2 of MRP1. Limited tryptic digestion of membrane vesicles expressing various truncated and co-expressed MRP1 fragments in the presence and absence of GSH revealed that GSH inhibited the production of the C2 fragment only in the presence of the L(0) region of MRP1. Thus the L(0) region is required for the inhibition of trypsinization of the C-terminal half of MRP1 by GSH. These findings, together with previous reports, suggest that GSH induces a conformational change at a site within the MRP1 that is indispensable for the interaction of MRP1 with its substrates.