Geranyl chalcone derivatives with antifungal and radical scavenging properties from the leaves of Artocarpus nobilis

Antifungal activity guided fractionation of the n-butanol extract from the methanol extract of the leaves of Artocarpus nobilis furnished 2',4',4-trihydroxy-3'-geranylchalcone (1), 2 ',4',4-trihydroxy-3'-[6-hydroxy-3,7-dimethyl-2(E),7-octadienyl]chalcone (2), 2',4',4-trihydroxy-3'-[2-hydroxy-7-methyl-3-methylene-6-octaenyl]chalcone (3), 2',3,4,4'-tetrahydroxy-3'-geranylchalcone (4), 2',3,4,4'-tetrahydroxy-3'-[6-hydroxy-3,7-dimethyl-2(E),7-octadienyl]chalcone (5). The chalcones 3 and 5 are new natural products whereas 1 and 2 are reported first time from the family Moraceae. All these compounds showed good fungicidal activity against Cladosporium cladosporioides and high radical scavenging activity towards the 2,2'-diphenyl-1-picrylhydrazyl (DPPH) radical in TLC bio-autography method.     

ARC3, a chloroplast division factor, is a chimera of prokaryotic FtsZ and part of eukaryotic phosphatidylinositol-4-phosphate 5-kinase

The arc3 (accumulation and replication of chloroplast) mutant of Arabidopsis thaliana has a small number of abnormally large chloroplasts in the cell, suggesting that chloroplast division is arrested in the mutant and ARC3 has an important role in the initiation of chloroplast division. To elucidate the role of ARC3, first we identified the ARC3 gene, and determined the location of ARC3 protein during chloroplast division because the localization and spatial orientation of such division factors are vital for correct chloroplast division. Sequencing analysis showed that ARC3 was a fusion of the prokaryotic FtsZ and part of the eukaryotic phosphatidylinositol-4-phosphate 5-kinase (PIP5K) genes. The PIP5K-homologous region of ARC3 had no catalytic domain but a membrane-occupation-and-recognition-nexus (MORN) repeat motif. Immunofluorescence microscopy, Western blotting analysis and in vitro chloroplast import and protease protection assays revealed that ARC3 protein was soluble, and located on the outer surface of the chloroplast in a ring-like structure at the early stage of chloroplast division. Prokaryotes have one FtsZ as a gene for division but have no ARC3 counterparts, the chimera of FtsZ and PIP5K, suggesting that the ARC3 gene might have been generated from FtsZ as another division factor during the evolution of chloroplast by endosymbiosis.     

Degradation of estrogens by Rhodococcus zopfii and Rhodococcus equi isolates from activated sludge in wastewater treatment plants

We have isolated four strains of Rhodococcus which specifically degrade estrogens by using enrichment culture of activated sludge from wastewater treatment plants. Strain Y 50158, identified as Rhodococcus zopfii, completely and rapidly degraded 100 mg of 17beta-estradiol, estrone, estriol, and ethinyl estradiol/liter, as demonstrated by thin-layer chromatography and gas chromatography-mass spectrometry analyses. Strains Y 50155, Y 50156, and Y 50157, identified as Rhodococcus equi, showed degradation activities comparable with that of Y 50158. Using the random amplified polymorphism DNA fingerprinting test, these three strains were confirmed to have been derived from different sources. R. zopfii Y 50158, which showed the highest activity among these four strains, revealed that the strain selectively degraded 17beta-estradiol during jar fermentation, even when glucose was used as a readily utilizable carbon source in the culture medium. Measurement of estrogenic activities with human breast cancer-derived MVLN cells showed that these four strains each degraded 100 mg of 17beta-estradiol/liter to 1/100 of the specific activity level after 24 h. It is thus suggested that these strains degrade 17beta-estradiol into substances without estrogenic activity.     

Synthesis and antibacterial activity of novel and potent DNA gyrase inhibitors with azole ring

The 4-piperidyl moiety and the pyrazole ring in 1-(3-chlorophenyl)-5-(4-phenoxyphenyl)-3-(4-piperidyl)pyrazole 2, which has previously shown improved DNA gyrase inhibition and target-related antibacterial activity, were transformed to other groups and the in vitro antibacterial activity of the synthesized compounds was evaluated. The selected pyrazole, oxazole and imidazole derivatives showed moderate inhibition against DNA gyrase and topoisomerase IV with similar IC(50) values (IC(50)=9.4-25 microg/mL). In addition, many of the pyrazole, oxazole and imidazole derivatives synthesized in this study exhibited potent antibacterial activity against quinolone-resistant clinical isolates and coumarin-resistant laboratory isolates of Gram-positive bacteria with minimal inhibitory concentration values equivalent to those against susceptible strains.     

Retrotransposon-mediated restoration of Chlorella telomeres: accumulation of Zepp retrotransposons at termini of newly formed minichromosomes

To elucidate the contribution of LINE-like retrotransposon Zepp elements to the formation and maintenance of chromosomal telomeres, newly formed minichromosomes in irradiated Chlorella vulgaris cells were isolated and structurally characterized. A minichromosome (miniV4) of ~700 kb in size contained a Zepp cluster taking the place of the telomeric repeats on one terminus, whereas the other end of this chromosome consisted of canonical telomeric repeats. The Zepp copies in this cluster were in a tandem array with their poly(A) tails towards the centromere. Another minichromosome Y32 (~400 kb in size) was shown to have several copies of Zepp elements on both termini. On the right arm terminus, two copies of Zepp were found in a tandem array with poly(A) tracts facing towards the chromosomal end. The poly(A) tail and the 3′-end of ~400 bp of the distal copy were replaced by the telomeric repeats. On the 5′-side of the proximal copy was another Zepp element in the reverse orientation. These newly formed telomeric structures are very similar to those previously found in the left arm of chromosome I and the terminus of an unidentified chromosome and support the model of Zepp-mediated restoration and maintenance of Chlorella telomeres.     

Crystal structure of Mg2+- and Ca2+-bound Gla domain of factor IX complexed with binding protein

Factor IX is an indispensable protein required in the blood coagulation cascade. It binds to the surface of phospholipid membrane by means of a gamma-carboxyglutamic acid (Gla) domain situated at the N terminus. Recently, we showed that physiological concentrations of Mg2+ ions affect the native conformation of the Gla domain and in doing so augment the biological activity of factor IXa and binding affinity with its binding protein even in the presence of Ca2+ ions. Here we report on the crystal structures of the Mg2+/Ca2+-bound and Ca2+-bound (Mg2+-free) factor IX Gla domain (IXGD1-46) in complex with its binding protein (IX-bp) at 1.55 and 1.80 A resolutions, respectively. Three Mg2+ and five Ca2+ ions were bound in the Mg2+/Ca2+-bound IXGD1-46, and the Mg2+ ions were replaced by Ca2+ ions in Mg2+-free IXGD1-46. Comparison of Mg2+/Ca2+-bound with Ca2+-bound structures of the complexes showed that Mg2+ ion, which formed a bridge between IXGD1-46 and IX-bp, forced IXGD1-46 to rotate 4 degrees relative to IX-bp and hence might be the cause of a more tight interaction between the molecules than in the case of the Mg2+-free structure. The results clearly suggest that Mg2+ ions are required to maintain native conformation and in vivo function of factor IX Gla domain during blood coagulation.     

The polyglycine and polyglutamine repeats in the androgen receptor gene in Japanese and Caucasian populations

Human androgen receptor (AR) gene contains two polymorphic trinucleotide repeats of CAG and GGC, which code for polyglutamine and polyglycine tracts in the N-terminal domain in which the receptor activity resides. Longer repeats induce decrease of transactivation function in the AR receptor, weaken an anti-proliferative effect on various steroid-related tissues, and may promote the carcinogenesis of these cancers, such as breast, endometrial, and ovarian cancers. However, the incidences of these steroid-related cancers are remarkably lower in Japanese than in Caucasians. We hypothesize that the GGC and CAG repeats in AR gene correspond to lower incidence of steroid-related cancers in the Japanese population. To test this hypothesis, these two polymorphic trinucleotide repeats in AR gene were genotyped in 221 Japanese and 177 Caucasians. The results of genotyping in these loci clearly show that the distribution of GGC repeat is significantly different between these populations (P<0.001). Japanese (73.7%) had 16 GGC repeats compared to 53.3% for Caucasians. Japanese (3.8%) also had 17 GGC repeats compared to 36.2% for Caucasians. No Japanese had more than 18 GGC repeats compared to 3.4% for Caucasians. The length of CAG repeats in the Japanese population was not significantly different than that of the Caucasian population, although the CAG repeats varied from 14 to 31 and 15 to 29 repeats in Japanese and German populations, respectively. This study demonstrates that the Japanese population has shorter GGC compared to the Caucasian population, which may explain the incidences of estrogen-related cancers in these populations.