An odorant derivative as an antagonist for an olfactory receptor

Different odorants are recognized by different combinations of G protein-coupled olfactory receptors, and thereby, odor identity is determined by a combinatorial receptor code for each odorant. We recently demonstrated that odorants appeared to compete for receptor sites to act as an agonist or an antagonist. Therefore, in natural circumstances where we always perceive a mixture of various odorants, olfactory receptor antagonism between odorants may result in a receptor code for the mixture that cannot be predicted from the codes for its individual components. Here we show that stored isoeugenol has an antagonistic effect on a mouse olfactory receptor, mOR-EG. However, freshly purified isoeugenol did not have an inhibitory effect. Instead, an isoeugenol derivative produced during storage turned out to be a potent competitive antagonist of mOR-EG. Structural analysis revealed that this derivative is an oxidatively dimerized isoeugenol that naturally occurs by oxidative reaction. The current study indicates that as odorants age, they decompose or react with other odorants, which in turn affects responsiveness of an olfactory receptor(s).     

Flower color modulations of Torenia hybrida by downregulation of chalcone synthase genes with RNA interference

Suppression of biosynthetic genes involved in flower color formation is an important approach for obtaining target flower colors. Here we report that flower color of the garden plant Torenia hybrida was successfully modulated by RNA interference (RNAi) against a gene of chalcone synthase (CHS), a key enzyme for anthocyanin and flavonoid biosynthesis. By using each of the coding region and the 3'-untranslated region of the CHS mRNA as an RNAi target, exhaustive and gene-specific gene silencing were successfully induced, and the original blue flower color was modulated to white and pale colors, respectively. Our results indicate that RNAi is quite useful for modulations of flower colors of commercially important garden plants.     

Comparison of pulmonary vascular response to endogenous nitric oxide inhibition in sheep and pigs living at 2,300 m

To compare the role of nitric oxide in an adaptive process to chronic hypoxia, we examined the effects of endogenous nitric oxide synthase inhibition on pulmonary vascular tone in conscious sheep and pigs living at high altitude. Unanesthetized male sheep (n=6) and pigs (n=5), born and residing in the highlands of Qinghai Province, China (2,300–3,000 m a.s.l.) were studied at that altitude. Pulmonary artery pressure (P_pa), pulmonary artery wedge pressure (P_cwp), and cardiac output (CO) were measured. Pulmonary vascular resistance (PVR) was calculated as (P_pa—P_cwp)/CO. Using a climatic chamber, hemodynamic measurements during exposures to atmospheric pressures corresponding to altitudes of 0, 2,300, and 4,500 m a.s.l. were performed with and without NO inhibition, using N^w-nitro-l-argine (NLA; 20 mg kg^–1), a potent stereospecific competitive inhibitor of nitric oxide synthase. P_pa and PVR at baseline (2,300 m) and during hypoxic exposure (4,500 m) were significantly higher in pigs than in sheep. After NLA administration, P_pa increased and CO decreased in both animals, resulting in significantly increased PVR at baseline and during hypoxic exposure. However, there were no significant differences in the percent increase in basal or hypoxic PVR after NLA administration between sheep and pigs. We conclude that augmented endogenous NO production could contribute to the regulation of pulmonary vascular tone at high altitude in sheep and pigs. However, it is unlikely that NO is responsible for the different pulmonary vascular tones between sheep and pigs at basal condition at moderately high altitude.Communicated by G. Heldmaier     

Role of primary sensorimotor cortex and supplementary motor area in volitional swallowing: a movement-related cortical potential study

We investigated the role of the cerebral cortex, particularly the face/tongue area of the primary sensorimotor (SMI) cortex (face/tongue) and supplementary motor area (SMA), in volitional swallowing by recording movement-related cortical potentials (MRCPs). MRCPs with swallowing and tongue protrusion were recorded from scalp electrodes in eight normal right-handed subjects and from implanted subdural electrodes in six epilepsy patients. The experiment by scalp EEG in normal subjects revealed that premovement Bereitschaftspotentials (BP) activity for swallowing was largest at the vertex and lateralized to either hemisphere in the central area. The experiment by epicortical EEG in patients confirmed that face/tongue SMI and SMA were commonly involved in swallowing and tongue protrusion with overlapping distribution and interindividual variability. BP amplitude showed no difference between swallowing and tongue movements, either at face/tongue SMI or at SMA, whereas postmovement potential (PMP) was significantly larger in tongue protrusion than in swallowing only at face/tongue SMI. BP occurred earlier in swallowing than in tongue protrusion. Comparison between face/tongue SMI and SMA did not show any difference with regard to BP and PMP amplitude or BP onset time in either task. The preparatory role of the cerebral cortex in swallowing was similar to that in tongue movement, except for earlier activation in swallowing. Postmovement processing of swallowing was lesser than that of tongue movement in face/tongue SMI; probably suggesting that the cerebral cortex does not play a significant role in postmovement processing of swallowing. SMA plays a supplementary role to face/tongue SMI both in swallowing and tongue movements.     

Synthesis and evaluation of substituted 4-alkoxy-2-aminopyridines as novel neuropeptide Y1 receptor antagonists

A series of substituted 4-alkoxy-2-aminopyridines 2, which were formally derived from neuropeptide Y1 antagonist 1 by replacing the morpholino portion with alkoxy groups, were synthesized and evaluated as neuropeptide Y Y1 receptor antagonists. Primary structure-activity relationships and identification of potent 4-alkoxy derivatives are described.     

2-Ureidoquinoline: a useful molecular element for stabilizing single cytosine and thymine bulges

We have demonstrated that aromatic heterocycles having hydrogen-bonding surfaces complementary to those of nucleotide bases are effective molecular elements for the binding to single nucleotide bulges and base mismatches. We here report that a new molecule, 2-ureidoquinoline having an alignment of hydrogen-bonding groups in the order of acceptor-donor-donor stabilizes single cytosine and thymine bulges in duplex DNAs. Furthermore, a dimeric form of 2-ureidoquinoline stabilizes cytosine-cytosine and cytosine-thymine mismatches.     

Intracellularly inducible, ubiquitin hydrolase-insensitive tandem ubiquitins inhibit the 26S proteasome activity and cell division

We constructed polyubiquitin derivatives that contain a tandem repeat of ubiquitins and were insensitive to ubiquitin hydrolases. They were designated tandem ubiquitin (tUb) with the number of repeats, such as tUb2. When tUbs were expressed under the control of the GAL1 promoter in the wild-type yeast strain, growth was strongly inhibited. Under these conditions, the degradation of N-end rule substrates, a UFD substrate and Gcn4 was inhibited, indicating that the tUb inhibits 26S proteasome activity. Consistent with this, tUb binds to the 26S proteasome. We showed that tUb inhibited the in vitro degradation of polyubiquitinylated Sic1 by the 26S proteasome. When tUB6 messenger RNA was injected into Xenopus embryos, cell division was inhibited, suggesting that tUb can be used as a versatile inhibitor of the 26S proteasome.     

The novel gene HOMOLOGOUS PAIRING ABERRATION IN RICE MEIOSIS1 of rice encodes a putative coiled-coil protein required for homologous chromosome pairing in meiosis

We have identified and characterized a novel gene, PAIR1 (HOMOLOGOUS PAIRING ABERRATION IN RICE MEIOSIS1), required for homologous chromosome pairing and cytokinesis in male and female meiocytes of rice (Oryza sativa). The pair1 mutation, tagged by the endogenous retrotransposon Tos17, exhibited meiosis-specific defects and resulted in complete sterility in male and female gametes. The PAIR1 gene encodes a 492-amino acid protein, which contains putative coiled-coil motifs in the middle, two basic regions at both termini, and a potential nuclear localization signal at the C terminus. Expression of the PAIR1 gene was detected in the early stages of flower development, in which the majority of the sporocytes had not entered meiosis. During prophase I of the pair1 meiocyte, all the chromosomes became entangled to form a compact sphere adhered to a nucleolus, and homologous pairing failed. At anaphase I and telophase I, chromosome nondisjunction and degenerated spindle formation resulted in multiple uneven spore production. However, chromosomal fragmentation frequent in plant meiotic mutants was never observed in all of the pair1 meiocytes. These observations clarify that the PAIR1 protein plays an essential role in establishment of homologous chromosome pairing in rice meiosis.     

Role of MMPs and plasminogen activators in angiogenesis after transmyocardial laser revascularization in dogs

We examined the role of matrix metalloproteinases (MMPs), tissue inhibitors of MMP (TIMPs), and plasminogen activator (PA) in transmyocardial laser revascularization (TMLR)-induced angiogenesis. TMLR was accomplished with a carbon dioxide laser in seven dogs whose left anterior descending coronary artery (LAD) was ligated. Seven control dogs underwent only LAD ligation, and four dogs underwent a sham operation, consisting only of a left thoracotomy. Two weeks later, transmural myocardial samples were harvested from the distributions of the LAD and the left circumflex artery for substrate zymography, immunohistochemical staining, and in situ zymography. MMP-1, MMP-2, TIMP-1, TIMP-2, and urokinase-type PA levels in the distribution of the LAD were higher in the laser group than in the control or sham group. Counts of von Willebrand factor-positive microvessels and smooth muscle alpha-actin-positive arterioles demonstrated that the angiogenesis and ateriogenesis was promoted in the laser group and correlated directly with the number of MMP-stained microvessels. We conclude that TMLR induces the expression of MMPs, TIMPs, and urokinase-type PA and that these proteinases play an important role in angiogenesis after TMLR.