The cloned human oestrogen receptor contains a mutation which alters its hormone binding properties.

We demonstrate here that the human oestrogen receptor (hER) cDNA clone pOR8 obtained from MCF-7 cells contains an artefactual point mutation which results in the substitution of a valine for a glycine at amino acid position 400 (Gly-400----Val-400). This mutation in the hormone binding domain of the cloned hER destabilizes its structure and decreases its apparent affinity for oestradiol at 25 degrees C, but not at 4 degrees C, when compared with the wild-type hER with a Gly-400.     

Possible linkage of the estrogen receptor gene to breast cancer in a family with late-onset disease.

The estrogen-receptor locus is a candidate gene for inherited susceptibility to human breast cancer, particularly among families with later onset, primarily estrogen-receptor-positive tumors. For one extended family with eight patients with late-onset disease, one estrogen-receptor haplotype was consistently coinherited with breast cancer, yielding a +1.85 lod score for linkage at zero recombination. Simulation of this pedigree assuming independent inheritance of breast cancer and estrogen-receptor genotypes led to a lod score greater than or equal to 1.85 only once in 2,000 replicates. We suggest testing linkage of this gene to breast cancer in other families with late-onset disease.     

Functional study of intracellular P-gp- and MRP1-mediated pumping of free cytosolic pirarubicin into acidic organelles in intrinsic resistant SiHa cells

We sought to determine the efficiency of the intracellular functional P-gp- and MRP1-mediated pumping of THP into acidic organelles in SiHa cells and etoposide-resistant SiHa/VP16 cells. The expression of both MDR1 and MRP1 genes of SiHa and SiHa/VP16 cells was clearly shown by using RT-PCR. The functional studies of both intracellular functional P-gp- and MRP1-mediated pumping were performed by using THP in a conventional spectrofluorometer, and they demonstrated that SiHa and SiHa/VP16 cells are good models to illustrate the functional role of intracellular P-gp and MRP1 in the transport of free cytosolic drug into acidic organelles. The functional P-gp and MRP1 proteins were identified both on plasma membranes and on intracellular vesicle membranes. Within the limit of experimental error, similar efficiencies in THP transport were observed in the two proteins at both locations in SiHa and SiHa/VP16 cells. The P-gp- and MRP1-mediated pump coefficient (k v a), Michealis-Menten's constant (K V m), and maximal pumping rate (V V max) values of those located on vesicular membranes were 1.87 +/- 0.30 pL x cell-1 x s-1, 1.63 +/- 0.21 microM, and 4.95 +/- 0.45 nM x s-1, respectively. Drug retention inside acidic organelles (C mon V) of SiHa cells was significantly higher than that of SiHa/VP16 cells, perhaps a consequence of slower movement of recycling endosomes and (or) lysosomes to the cell membrane of SiHa cells, leading to distended organelles and cell death. Our results suggest that intracellular P-gp and MRP1 proteins play an important role in the transport of free drug from cytosol to cytoplasmic acidic organelles.     

A novel detection of a single Plasmodium falciparum in infected blood

Detection of Plasmodium falciparum malaria by a specific DNA probe is a highly promising means for epidemiological surveillance of human malaria. However, none of presently available DNA probe methods could detect as little as a few parasites in infected blood. By amplification of a specific 206 base pairs P. falciparum DNA sequence using the polymerase chain reaction (PCR), as little as 0.01 picogram DNA or one-half of a parasite was sufficient for a specific detection. A PCR procedure for detection of P. falciparum in infected blood without prior DNA extraction was also developed which was sensitive for a single parasite. The procedure was simple and should be applicable for a large scale epidemiological study involving a very low parasitemia situation.     

Stage specificity of Plasmodium falciparum telomerase and its inhibition by berberine

Telomerase activity in synchronized Plasmodium falciparum during its erythrocytic cycle was examined using the TRAP assay. Telomerase activity was detected at all stages of the parasite intraerythrocyte development, with higher activity in trophozoite and schizont stages compared with ring form. Berberine, extracted from Arcangelisia flava (L.) Merr., inhibited telomerase activity in a dose-dependent manner over a range of 30-300 microM, indicating that P. falciparum telomerase might be a potential target for future malaria chemotherapy.     

Higher plant-like fluorescence induction and thermoluminescence characteristics in cyanobacterium, Spirulina mutant defective in PQH2 oxidation by cytb6/f complex

Characterization of the photosynthetic electron transport in a mutant of Spirulina platensis, generated by chemical mutagenesis, demonstrated that the electron transfer from the plastoquinone (PQ) to cytochrome b6/f was slowed. Thermoluminescence (TL) measurements suggested the presence of reversed energy flow via PQ, which resulted in an emergence of the plant-like after-glow TL band at 45 degrees C that could be enhanced by the transthylakoidal pH gradient and could be eliminated by an uncoupler, FCCP. The localization of the changes in the electron transport of the mutant cells measured by various methods revealed that the re-oxidation of the PQ pool is hampered in the mutant compared to the wild-type cells. The reduction in energy migration was localized between PQ and PS I reaction centers.     

Isolation and characterization of microsatellite markers from the great hornbill, Buceros bicornis

Thirteen polymorphic microsatellite markers were isolated and characterized from the great hornbill, Buceros bicornis. In analyses of 20 individuals, the numbers of alleles per locus varied from two to 11. The expected and observed heterozygosities ranged from 0.22 to 0.88 and from 0.20 to 1.00, respectively. The mean polymorphic information content was 0.62. Among these, three loci deviated from the Hardy-Weinberg equilibrium. However, no significant genotypic disequilibrium was detected between any pair of loci. These microsatellite markers are useful for the population genetic study of the great hornbill.     

A phylogeny of frugivorous hornbills linked to the evolution of Indian plants within Asian rainforests

Understanding the origin and radiation of modern Asian hornbills and the influential ecological roles they play as seed dispersal agents within Asian rainforests should help reveal the evolution of these roles. We constructed a dated phylogeny of hornbills using mitochondrial DNA sequences of the cytochrome b gene and discovered that all clades leading to frugivorous hornbills originated in the mid-Eocene ～48 Ma. This 'explosive' radiation coincided with a remarkable floral invasion of Asian rainforests from the Indian microcontinent. Analysis of phylogenetic data, in conjunction with palaeontological events, suggests that the invasion of distinctive flora comprised two waves, one during the mid-Eocene, when India was offshore of the Sunda Shelf, and the other late Eocene, when India collided with the Asian mainland. We propose that frugivorous vertebrates, such as hornbills, were present during the first wave and assisted rapid colonization of the Asian flora.