Flexibility of small molecular CD4 mimics as HIV entry inhibitors

CD4 mimics such as YIR-821 and its derivatives are small molecules which inhibit the interaction between the Phe43 cavity of HIV-1 gp120 with host CD4, an interaction that is involved in the entry of HIV to cells. Known CD4 mimics generally possess three structural features, an aromatic ring, an oxalamide linker and a piperidine moiety. We have shown previously that introduction of a cyclohexyl group and a guanidine group into the piperidine moiety and a fluorine atom at the meta-position of the aromatic ring leads to a significant increase in the anti-HIV activity. In the current study, the effects of conformational flexibility were investigated by introduction of an indole-type group in the junction between the oxalamide linker and the aromatic moiety or by replacement of the oxalamide linker with a glycine linker. This led to the development of compounds with high anti-HIV activity, showing the importance of the junction region for the expression of high anti-HIV activity. The present data are expected to be useful in the future design of novel CD4 mimic molecules.     

Parallel formation of hybrid swarms of ground beetles in the genus Carabus (Coleoptera: Carabidae) in adjacent river basins

Populations of forms intermediate between Carabus (Ohomopterus) insulicola and Carabus (Ohomopterus) arrowianus occur at the boundaries between the two species in the Kiso Valley, Nagano Prefecture, central Honshu, Japan. Morphological and mitochondrial DNA analyses revealed that these populations are derived from a hybrid swarm established as a result of secondary contact between the two species. A similar hybrid swarm has been reported in the Ina Valley, an adjacent river basin separated by the Kiso Mountain Range, where the two species are distributed parapatrically. The hybrid swarm individuals in the two valleys show parallelism in the morphological evolution of the male genitalia upon secondary contact and subsequent formation of hybrid swarms between the two Carabus species.     

Role of F225 in <Emphasis Type="Italic">O</Emphasis>-phosphoserine sulfhydrylase from <Emphasis Type="Italic">Aeropyrum pernix</Emphasis> K1

O-Phosphoserine sulfhydrylase (OPSS) synthesizes cysteine from O-phospho-l-serine (OPS) and sulfide. We have determined the three-dimensional structures of OPSS from hyperthermophilic archaeon Aeropyrum pernix K1 (ApOPSS) in complex with aminoacrylate intermediate (AA) formed from pyridoxal 5′-phosphate with OPS or in complex with cysteine and compared them with that of ApOPSS. We found an orientational change of F225 at the active-site entrance and constructed an F225A mutant to examine its activities and AA stability and clarify the role of F225 in ApOPSS. The OPS and O-acetyl-l-serine (OAS) sulfhydrylase activities of the F225A mutant decreased by 4.2- and 15-fold compared to those of the wild-type (wt) ApOPSS, respectively. The ability of OPS and OAS to form AA also decreased by 12- and 27-fold, respectively. AA was less stable in the F225A mutant than in the wt ApOPSS. Simulated docking showed that leaving groups, such as phosphate and acetate, were oriented to the inside of the active site in the F225A mutant, whereas they were oriented to the entrance in the wt ApOPSS. These results suggest that F225 in ApOPSS plays important roles in maintaining the hydrophobic environment of AA from solvent water and in controlling the orientation of leaving groups.     

A high molecular weight glycoprotein in seminal plasma is a sperm immobilizing factor in the teleost Nile tilapia, Oreochromis niloticus

Sperm that have acquired potential for motility are kept immotile in seminal plasma in the teleost, Nile tilapia. In order to investigate the mechanism of immobilization, several experiments were performed using a previously characterized monoclonal antibody (TAT-30) against a molecular weight (Mr) = 120,000 protein that is secreted by Sertoli cells and epithelial cells of the sperm duct, and is also bound to the head of the spermatozoon. First, we assessed sperm motility in the seminal plasma protein fraction (SPP), and demonstrated that the sperm motility is inhibited by SPP in a concentration-dependent manner. Furthermore, sperm motility was recovered if SPP was pretreated with TAT-30, suggesting that the TAT-30 antigen is one of the components of the sperm immobilizing factor. Calibration by gel filtration followed by sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and western blotting with TAT-30 demonstrated that the sperm immobilizing factor was more than Mr = 1,000,000 in seminal plasma, suggesting that it is a homopolymer of the Mr = 120,000-TAT-30 positive protein. Additionally, lectin blot analysis showed that the TAT-30 antigen was reactive with Lens culinarin agglutinin (LCA) and Conavalia ensiformis agglutinin (ConA), indicating that it is a glycoprotein. Immunohistochemical studies showed that the TAT-30 antigen was localized specifically on the heads of spermatozoa and on the apical surface, lysosomes and rough endoplasmic reticulum of Sertoli cells.     

Heat shock proteins mediate trade‐offs between early‐life reproduction and late survival in Drosophila melanogaster

Ageing and the resulting increased likelihood mortality are the inescapable fate of organisms because selection pressures on genes that exert their function late in life is weak, promoting the evolution of genes that enhance early‐life reproductive performance at the same time as sacrificing late survival. Heat shock proteins (HSP) are known to buffer various environmental stresses and are also involved in protein homeostasis and longevity. The characteristics of genes for HSPs (hsp) imply that they affect various life‐history traits, which in turn affect longevity; however, little is known about the effects of hsp genes on life‐history traits and their interaction with longevity. In the present study, the effects of hsp genes on multiple fitness traits, such as locomotor activity, total fecundity, early fecundity and survival time, are investigated in Drosophila melanogaster Meigen using RNA interference (RNAi). In egg‐laying females, RNAi knockdown of six hsp genes (hsp22, hsp23, hsp67Ba, hsp67Bb, hsp67Bc and hsp27‐like) does not shorten survival but rather increases it. Knockdown of five of those genes on an individual basis reduces early‐life reproduction, suggesting that several hsp genes mediate the trade‐off between early reproduction and late survival. The data indicate a positive effect of hsp genes on early reproduction and also negative effects on survival time, supporting the antagonistic pleiotropic effects predicted by the optimality theory of ageing.     

The Gentio-Oligosaccharide Gentiobiose Functions in the Modulation of Bud Dormancy in the Herbaceous Perennial Gentiana

Bud dormancy is an adaptive strategy that perennials use to survive unfavorable conditions. Gentians (Gentiana), popular alpine flowers and ornamentals, produce overwintering buds (OWBs) that can persist through the winter, but the mechanisms regulating dormancy are currently unclear. In this study, we conducted targeted metabolome analysis to obtain clues about the metabolic mechanisms involved in regulating OWB dormancy. Multivariate analysis of metabolite profiles revealed metabolite patterns characteristic of dormant states. The concentrations of gentiobiose [β-d-Glcp-(1→6)-d-Glc] and gentianose [β-d-Glcp-(1→6)-d-Glc-(1→2)-d-Fru] significantly varied depending on the stage of OWB dormancy, and the gentiobiose concentration increased prior to budbreak. Both activation of invertase and inactivation of β-glucosidase resulted in gentiobiose accumulation in ecodormant OWBs, suggesting that gentiobiose is seldom used as an energy source but is involved in signaling pathways. Furthermore, treatment with exogenous gentiobiose induced budbreak in OWBs cultured in vitro, with increased concentrations of sulfur-containing amino acids, GSH, and ascorbate (AsA), as well as increased expression levels of the corresponding genes. Inhibition of GSH synthesis suppressed gentiobiose-induced budbreak accompanied by decreases in GSH and AsA concentrations and redox status. These results indicate that gentiobiose, a rare disaccharide, acts as a signal for dormancy release of gentian OWBs through the AsA-GSH cycle.