The Expression Level of HIV-1 Vif Is Optimized by Nucleotide Changes in the Genomic SA1D2prox Region during the Viral Adaptation Process.

HIV-1 Vif plays an essential role in viral replication by antagonizing anti-viral cellular restriction factors, a family of APOBEC3 proteins. We have previously shown that naturally-occurring single-nucleotide mutations in the SA1D2prox region, which surrounds the splicing acceptor 1 and splicing donor 2 sites of the HIV-1 genome, dramatically alter the Vif expression level, resulting in variants with low or excessive Vif expression. In this study, we investigated how these HIV-1 variants with poor replication ability adapt and evolve under the pressure of APOBEC3 proteins. Adapted clones obtained through adaptation experiments exhibited an altered replication ability and Vif expression level compared to each parental clone. While various mutations were present throughout the viral genome, all replication-competent adapted clones with altered Vif expression levels were found to bear them within SA1D2prox, without exception. Indeed, the mutations identified within SA1D2prox were responsible for changes in the Vif expression levels and altered the splicing pattern. Moreover, for samples collected from HIV-1-infected patients, we showed that the nucleotide sequences of SA1D2prox can be chronologically changed and concomitantly affect the Vif expression levels. Taken together, these results demonstrated the importance of the SA1D2prox nucleotide sequence for modulating the Vif expression level during HIV-1 replication and adaptation.

Elucidation of Inverse Agonist Activity of Bilastine.

H1-antihistamines antagonize histamine and prevent it from binding to the histamine H1 receptor (H1R). Some of them also act as inverse agonists, which are more potent than pure antagonists because they suppress the constitutive H1R activity. Bilastine is a non-sedative antihistamine which is one of the most satisfy the requirements for oral antihistamines. However, there is no information to show the inverse agonist activity of bilastine including inositol phosphates accumulation, and its inverse agonist activity is yet to be elucidated. Here we evaluated whether bilastine has inverse agonist activity or not. Intracellular calcium concentration was measured using Fluo-8. Inositol phosphates accumulation was assayed using [3H]myo-inositol. The H1R mRNA level was measured using real-time RT-PCR. At rest, Ca2+ oscillation was observed, indicating that H1R has intrinsic activity. Bilastine attenuated this fluorescence oscillation. Bilastine suppressed the increase in IPs formation in a dose-dependent manner and it was about 80% of the control level at the dose of 3 µM. Bilastine also suppressed histamine-induced increase in IPs formation to the control level. Furthermore, bilastine suppressed basal H1R gene expression in a dose-dependent manner. Data suggest that bilastine is an inverse agonist. Preseasonal prophylactic administration with bilastine could down-regulate basal H1R gene expression in the nasal mucosa and ameliorate the nasal symptoms during the peak pollen period.

Synthesis of resveratrol glycosides by cultured plant cells.

Incubation of cultured cells of Glycine max with trans-resveratrol gave its 3-O-beta-D- and 4'-O-beta-D-glucosides. Cultured Gossypium hirsutum cells glycosylated trans-resveratrol to its 3-O-beta-D-, 4'-O-beta-D-, and 3,4'-O-beta-D-diglucosides. On the other hand, trans-resveratrol was converted into cis-resveratrol 4'-O-beta-D-glucoside, together with trans-resveratrol 3-O-beta-D-glucoside and trans-resveratrol 4'-O-beta-D-glucoside, by Eucalyptus perriniana.

A study to control chemical reactions using Si:2p core ionization: site-specific fragmentation.

In an aim to create a "sharp" molecular knife, we have studied site-specific fragmentation caused by Si:2p core photoionization of bridged trihalosilyltrimethylsilyl molecules in the vapor phase. Highly site-specific bond dissociation has been found to occur around the core-ionized Si site in some of the molecules studied. The site specificity in fragmentation and the 2p binding energy difference between the two Si sites depend in similar ways on the intersite bridge and the electronegativities of the included halogen atoms. The present experimental and computational results show that for efficient "cutting" the following conditions for the two atomic sites to be separated by the knife should be satisfied. First, the sites should be located far from each other and connected by a chain of saturated bonds so that intersite electron migration can be reduced. Second, the chemical environments of the atomic sites should be as different as possible.

Site-specific fragmentation caused by core-level photoionization in F(3)SiCH(2)CH(2)Si(CH(3))(3) vapor: comparison between Si:1s and 2p photoionizations by means of photoelectron-photoion-photoion triple-coincidence spectroscopy.

Site-specific fragmentation caused by Si:1s and 2p core-level photoionizations in F(3)SiCH(2)CH(2)Si(CH(3))(3) vapor was studied by energy-selected-photoelectron photoion-photoion triple-coincidence spectroscopy. The difference between the chemical shifts of the two Si sites is larger for the 1s ionization than for the 2p (2s) ionization. The fragmentation caused by the Si:1s ionization is more violent than that caused by the Si:2p ionization. The ions and ion pairs showing high site specificity for the Si:1s ionization belong to small fragments compared to those in the Si:2p ionization. Criteria for high site-specificity in fragmentation are discussed in conjunction with the present results.

UV protection and singlet oxygen quenching activity of aloesaponarin I.

The UV protection and singlet oxygen quenching of aloesaponarin I have been studied by means of laser spectroscopy. The excited-state intramolecular proton transfer that provides the UV protection takes place along only one of the molecule's two intramolecular hydrogen bonds, and this can be understood by considering the nodal pattern of the wave function. The functional groups participating in the excited-state intramolecular proton transfer also play important roles in the singlet oxygen quenching. Aloesaponarin I has a quenching rate constant larger than that of vitamin E and has a long duration of action due to its resistance to UV degradation and chemical attacks by singlet oxygen and free radicals.