Structure and luminescence of sodium and lanthanide(III) coordination polymers with pyridine-2,6-dicarboxylic acid

A series of coordination polymers constructed by sodium, lanthanide(III), and pyridine-2,6-dicarboxylate (dipic),NaLn(dipic)₂ · 7H₂O (Ln = Eu, Gd, Tb), have been prepared under a hydrothermal condition. The crystal structures of the three compounds which are isostructual were determined by single-crystal X-ray diffraction. The two-dimensional layers found in the compounds are built up from six-folded {NaO₆} polyhedra and nine-folded {LnN₂O₇} polyhedra, these being edge-shared each other along the c axis and bridged by carboxylate groups of dipic along the b axis, respectively. This two-dimensional framework provides cavities inside the layer and interlayer spaces outside the layer for accommodation of the two dipic molecules coordinated to a lanthanide(III) ions. The dehydrated materials obtained by heating the as-synthesized crystals at 200 °C held their crystal structure, and absorbed the same amounts of water molecules as those of the as-synthesized crystals upon the exposure of 100% relative humidity at room temperature. The Eu and Tb compounds showed strong red and green emissions, respectively, due to an energy transfer from dipic molecules to trivalent emission ions.     

Isolation and characterization of microsatellite loci in an endangered tree species, Afzelia xylocarpa (Kurz) Craib (Caesalpinioideae)

Afzelia xylocarpa is listed as an endangered species on the International Union for the Conservation of Nature and Natural Resources World list of Threatened Trees, due to overexploitation for its valuable timber and habitat loss. We isolated eight polymorphic microsatellite loci from A. xylocarpa using dual suppression polymerase chain reaction technique. These loci provide microsatellite markers with high polymorphism, as the number of alleles ranged from two to seven, and the estimate of gene diversity was between 0.285 and 0.795. The markers are now available for more detailed investigation of population genetic structure and gene flow among A. xylocarpa populations.     

Development of microsatellite and amplicon length polymorphism markers for Camellia japonica L. from tea plant (Camellia sinensis) expressed sequence tags

Simple sequence repeats and amplicon length polymorphism markers for Camellia japonica were developed, based on Camellia sinensis sequences in the National Center for Biotechnology Information database. In total, 2495 gene sequences were used to design 216 primer pairs. To identify amplicon length polymorphism markers, 61 gene loci in 16 Camellia individuals were re-sequenced. In total, 10 markers (three expressed sequence tags-simple sequence repeats and seven amplicon length polymorphisms) yielded polymerase chain reaction products with clear polymorphic patterns and were used for genotyping 22 C. japonica individuals from a population. Numbers of alleles and expected heterozygosity ranged from two to 13 and from 0.28 to 0.90, respectively.     

Management units of the endangered herb Primula sieboldii based on microsatellite variation among and within populations throughout Japan

To promote programs for the conservation and restoration of the endangered species Primula sieboldii, we examined genetic variation at eight microsatellite loci among and within 32 remnant wild populations throughout Japan. Total allelic diversity within a population was higher in larger populations, but not so after rarefaction adjustment. The positive relationship between population size and the inbreeding coefficient may suggest that more heterozygous genets tend to survive the habitat contraction possibly because of the higher fitness associated with heterozygosity. By principal coordinate analysis and Bayesian analysis, we detected four genetic groups (Hokkaido, northern Honshu, central Honshu, and western Japan), which could be recognized as management units of P. sieboldii. If supplementation with plants from other populations were planned, it should be conducted among populations which belong to the same management unit and which are likely to represent the same adaptive variation.     

Effects of modification of 4-thiouridine in E. coli tRNAfMet on methylation reaction with a thermostable Gm-methylase

Gm-methylase isolated from an extreme thermophile, Thermus thermophilus HB 27 methylates the 2'-OH of the ribose of G18 in the consensus GG sequence in the D loop, by recognizing the D loop-and-stem structure as a minimal substrate. Modification of s4U8 of E. coli tRNAfMet with S-benzylthioisothiourea resulted in a considerable decrease in methylation activity of Gm-methylase. The effect was cancelled by reduction with beta-mercaptoethanol. However, aminoacylation activity and methylation activity of m1A-methylase were scarcely influenced by the modification. These results suggest the involvement of s4U8 residue of tRNA in the recognition of Gm-methylase.     

Effects of flanking genes on the phenotypes of mice deficient in basigin/CD147

The induction of null mutations by means of homologous recombination is a powerful technique for clarifying the biological activities of target genes. However, the problems of the genetic background and flanking genes should be borne in mind. Here we employed a breeding strategy to compare three lines of mice deficient in the basigin (Bsg)/CD147 gene. The first line was F2 from F1 hybrid offspring of the 129/SV chimera and C57BL/6J. The second one was from a C57BL/6J congenic line. Both lines showed high embryonic lethality, sterility, and blindness. The third one was 'reverse F2' from 'reverse F1' hybrid offspring of the C57BL/6J congenic line and 129/SV. Surprisingly, this line showed a normal birth rate, while sterility and blindness persisted. Our results clearly separate the effects of the induced null mutation from those of flanking genes and the genetic background, and provide a useful means of investigating the biological functions of Bsg.     

High density lipoprotein-induced endothelial nitric-oxide synthase activation is mediated by Akt and MAP kinases

High density lipoprotein (HDL) activates endothelial nitric-oxide synthase (eNOS), leading to increased production of the antiatherogenic molecule NO. A variety of stimuli regulate eNOS activity through signaling pathways involving Akt kinase and/or mitogen-activated protein (MAP) kinase. In the present study, we investigated the role of kinase cascades in HDL-induced eNOS stimulation in cultured endothelial cells and COS M6 cells transfected with eNOS and the HDL receptor, scavenger receptor B-I. HDL (10-50 microg/ml, 20 min) caused eNOS phosphorylation at Ser-1179, and dominant negative Akt inhibited both HDL-mediated phosphorylation and activation of the enzyme. Phosphoinositide 3-kinase (PI3 kinase) inhibition or dominant negative PI3 kinase also blocked the phosphorylation and activation of eNOS by HDL. Studies with genistein and PP2 showed that the nonreceptor tyrosine kinase, Src, is an upstream stimulator of the PI3 kinase-Akt pathway in this paradigm. In addition, HDL activated MAP kinase through PI3 kinase, and mitogen-activated protein kinase/extracellular signal-regulated kinase kinase inhibition fully attenuated eNOS stimulation by HDL without affecting Akt or eNOS Ser-1179 phosphorylation. Conversely, dominant negative Akt did not alter HDL-induced MAP kinase activation. These results indicate that HDL stimulates eNOS through common upstream, Src-mediated signaling, which leads to parallel activation of Akt and MAP kinases and their resultant independent modulation of the enzyme.     

Kohamaic acid A,a novel sesterterpenic acid,inhibits activities of DNA polymerases from deuterostomes

We previously found and isolated a novel natural product, designated kohamaic acid A (KA-A), which inhibited the first cleavage of fertilized sea urchin eggs. In this paper, we report that this compound could selectively inhibit the activities of DNA polymerases (pol. alpha, beta, gamma, delta and epsilon ) only from species in the deuterostome branch in the animal kingdom, like sea urchin, fish and mammals, but not from protostomes including insects (fruit fly, Drosophila melanogaster) and mollusks (octopus and oyster). Inhibition of deuterostome DNA polymerases was dose dependent. IC(50) values for DNA polymerases of mammals and fish occurred at approximately 5.8-14.9 microM and those of sea urchin at 6.1-30.3 microM. In the sea urchin DNA polymerases, the activities of the replicative DNA polymerases such as alpha, delta and epsilon were more strongly inhibited than that of the repair-related pol. beta. KA-A is an inhibitor of replicative DNA polymerases from the deuterostome species, and subsequently, the inhibition of the first cleavage of fertilized sea urchin eggs might occur as a result of the suppression of DNA replication.