New evidence of reproductive organs of <Emphasis Type="Italic">Glossopteris</Emphasis> based on permineralized fossils from Queensland,Australia. I. Ovulate organ <Emphasis Type="Italic">Homevaleia</Emphasis> gen. nov.

This study describes Homevaleia gouldii H. Nishida, Pigg, Kudo et Rigby gen. et sp. nov., an ovule-bearing glossopterid organ, based on a combination of recently collected permineralized specimens from the Late Permian Homevale Station locality in the Bowen Basin of Queensland, Australia, and on previously studied material from the 1977 Gould and Delevoryas study. Homevaleia, which resembles the compression–impression genus Dictyopteridium, is an inrolled megasporophyll with a distinct keel that bears numerous (over 70) stalked ovules on its adaxial surface. Ovules are small, oval, with an elaborate mesh-like structure that is developed from the outermost integumentary layers. Specimens interpreted as representing different developmental stages show there is an apparent interrelationship between megagametophyte development and the opening of the surrounding fertile structure for pollination. Together, new information provided by this material enables better understanding of glossopterid reproductive structure and its function in one distinctive form.     

Flavonoids induce germination of basidiospores of the ectomycorrhizal fungus <Emphasis Type="Italic">Suillus bovinus</Emphasis>

Under laboratory conditions, spores of ectomycorrhizal fungi usually germinate very poorly or not at all. In a previous study, we showed that spores of the ectomycorrhizal fungus Suillus bovinus germinated through the combination of activated charcoal treatment of media and co-culture with seedlings of Pinus densiflora, which suggested that some substances contained in root exudates induced the germination. Among the compounds reported from root exudates, flavonoids have been elucidated to play various and substantial roles in plant–microbe interactions; we therefore investigated the effects of flavonoids on basidiospore germination of S. bovinus by the diffusion gradient assay on water agar plates pretreated with charcoal powder. Seven out of the 11 flavonoids tested, hesperidin, morin, rutin, quercitrin, naringenin, genistein, and chrysin, had greater effects than controls, whereas flavone, biochanin A, luteolin, and quercetin showed no positive effects. The effective concentration presumably corresponded to several micromolar levels, which was equivalent to those effective for pollen development, nod gene induction, and spore germination of F. solani f. sp. pisi and AM fungi. The results suggest that flavonoids play a role as signaling molecules in symbiotic relationships between woody plants and ectomycorrhizal fungi.     

Body‐colour variation in an orb‐web spider and its effect on predation success

Animal body coloration serves several functions such as thermoregulation, camouflage, aposematism, and intraspecific communication. In some orb‐web spiders, bright and conspicuous body colours are used to attract prey. On the other hand, there are other species whose body colour does not attract prey. Using a spider species showing individual body‐colour variation, the present study aimed to determine whether or not the variation in body colour shows a correlation with predation rates. We studied the orb‐web spider (Cyclosa argenteoalba) using both field observations and T‐maze experiments, in which the prey were exposed to differently coloured spiders. Cyclosa argenteoalba has silver‐ and black‐coloured areas on its dorsal abdomen, with the ratio of these two colours varying continuously among individuals. The bright and conspicuous silver area reflects ultraviolet light. Results of both field observations and colour choice experiments using Drosophila flies as prey showed that darker spiders have a greater chance of capturing prey than silver spiders. This indicates that body‐colour variation affects predation success among individuals and that the bright silver colour does not function to attract prey in C. argenteoalba.     

Structure-activity relationship studies of sphingosine-1-phosphate receptor agonists with N-cinnamyl-β-alanine moiety

Structure-activity relationship of sphingosine-1-phosphate receptor agonist was examined. In terms of reducing the flexibility of molecule, hit compound 1 was modified to improve S1P₁ agonistic activity as well as selectivity over S1P₃ agonistic activity. Novel S1P agonists with cinnamyl scaffold or 1,2,5,6-tetrahydropyridine scaffold were identified.     

6,7-Dihydro-5H-cyclopenta[d]pyrazolo[1,5-a]pyrimidines and their derivatives as novel corticotropin-releasing factor 1 receptor antagonists

To identify an orally active corticotropin-releasing factor 1 receptor antagonist, a series of 6,7-dihydro-5H-cyclopenta[d]pyrazolo[1,5-a]pyrimidines and their derivatives were designed, synthesized and evaluated. An in vitro study followed by in vivo and pharmacokinetic studies of these heterotricyclic compounds led us to the discovery of an orally active CRF1 receptor antagonist. The results of a structure-activity relationship study are presented.     

Arsonic acid-presenting superparamagnetic iron oxide for pH-responsive aggregation under slightly acidic conditions

We report the synthesis and characterization of the arsonic acid-presenting superparamagnetic iron oxide (SPIO). We used arsonoacetic acid as the ligand for SPIOs in aqueous media. The surface modification of the SPIOs was accomplished via the ligand exchange from undecanoic acid to the carboxyl moiety of arsonoacetic acid. Consequently, the well-dispersed arsonic acid-presenting SPIOs in water were obtained. We found that the dispersion state of the arsonic acid-presenting SPIOs can be sharply regulated by pH changes in the biological significant region. The well dispersion state of the arsonic acid-presenting SPIOs can be maintained at the neutral pH region. In contrast, the arsonic acid-presenting SPIOs can sensitively form the aggregation below pH 6.1. Moreover, these dispersion states can be controlled reversibly by the pH alteration in the narrow region.     

Two new subfamilies of DNA mismatch repair proteins (MutS) specifically abundant in the marine environment

MutS proteins are ubiquitous in cellular organisms and have important roles in DNA mismatch repair or recombination. In the virus world, the amoeba-infecting Mimivirus, as well as the recently sequenced Cafeteria roenbergensis virus are known to encode a MutS related to the homologs found in octocorals and ɛ-proteobacteria. To explore the presence of MutS proteins in other viral genomes, we performed a genomic survey of four giant viruses (‘giruses'') (Pyramimonas orientalis virus (PoV), Phaeocystis pouchetii virus (PpV), Chrysochromulina ericina virus (CeV) and Heterocapsa circularisquama DNA virus (HcDNAV)) that infect unicellular marine algae. Our analysis revealed the presence of a close homolog of Mimivirus MutS in all the analyzed giruses. These viral homologs possess a specific domain structure, including a C-terminal HNH-endonuclease domain, defining the new MutS7 subfamily. We confirmed the presence of conserved mismatch recognition residues in all members of the MutS7 subfamily, suggesting their role in DNA mismatch repair rather than DNA recombination. PoV and PpV were found to contain an additional type of MutS, which we propose to call MutS8. The MutS8 proteins in PoV and PpV were found to be closely related to homologs from ‘Candidatus Amoebophilus asiaticus'', an obligate intracellular amoeba-symbiont belonging to the Bacteroidetes. Furthermore, our analysis revealed that MutS7 and MutS8 are abundant in marine microbial metagenomes and that a vast majority of these environmental sequences are likely of girus origin. Giruses thus seem to represent a major source of the underexplored diversity of the MutS family in the microbial world.