A single recessive gene controls cadmium translocation in the cadmium hyperaccumulating rice cultivar Cho-Ko-Koku

The heavy metal cadmium (Cd) is highly toxic to humans and can enter food chains from contaminated crop fields. Understanding the molecular mechanisms of Cd accumulation in crop species will aid production of safe Cd-free food. Here, we identified a single recessive gene that allowed higher Cd translocation in rice, and also determined the chromosomal location of the gene. The Cd hyperaccumulator rice variety Cho-Ko-Koku showed 3.5-fold greater Cd translocation than the no-accumulating variety Akita 63 under hydroponics. Analysis of an F₂ population derived from these cultivars gave a 1:3 segregation ratio for high:low Cd translocation. This indicates that a single recessive gene controls the high Cd translocation phenotype. A QTL analysis identified a single QTL, qCdT7, located on chromosome 7. On a Cd-contaminated field, Cd accumulation in the F₂ population showed continuous variation with considerable transgression. Three QTLs for Cd accumulation were identified and the peak of the most effective QTL mapped to the same region as qCdT7. Our data indicate that Cd translocation mediated by the gene on qCdT7 plays an important role in Cd accumulation on contaminated soil.     

Repeated oral administration of a squeezed ginger (Zingiber officinale) extract augmented the serum corticosterone level and had anti-inflammatory properties

We investigated the ability of a ginger extract to induce an immune response in RAW 264 cells and after a repeated oral administration to mice. The squeezed ginger extract augmented the production of tumor necrosis factor-α, interleukin-6, and monocyte chemotactic protein-1 when added to RAW 264 cells. This extract was collected as its ethanol-insoluble fraction. The oral administration of the squeezed ginger extract or its ethanol-insoluble fraction once or twice to mice also augmented the tumor necrosis factor-α production in peritoneal cells; however, its long-term administration had the opposite effect. The serum corticosterone level had increased after orally administering the squeezed ginger extract and was maintained during the administration period. Oral administration of the squeezed ginger extract also inhibited arachidonic acid-induced ear edema, but its repeated administration was needed to achieve an anti-inflammatory effect. These results suggest that the repeated administration of the aqueous constituents of ginger augmented the serum corticosterone level and that this may have gradually induced anti-inflammatory activity.     

Seven of eight species in Nicotiana section Suaveolentes have common factors leading to hybrid lethality in crosses with Nicotiana tabacum

Background and Aims

Reproductive isolation is a mechanism that separates species, and is classified into two types: prezygotic and postzygotic. Inviability of hybrids, or hybrid lethality, is a type of postzygotic isolation and is observed in some plant species, including Nicotiana species. Previous work has shown that the Q chromosome, which belongs to the S subgenome of N. tabacum, encodes one or more genes leading to hybrid lethality in some crosses.

Methods

Interspecific crosses of eight wild species were conducted in section Suaveolentes (which consists of species restricted to Australasia and Africa) with the cultivated species Nicotiana tabacum. Hybrid seedlings were cultivated at 28, 34 or 36 °C, and PCR and chromosome analysis were performed.

Results and Conclusions

Seven of eight wild species produced inviable hybrids after crossing. Hybrid lethality, which was observed in all crosses at 28 °C, was Type II lethality, with the characteristic symptoms of browning of hypocotyl and roots; lethality was suppressed at elevated temperatures (34 or 36 °C). Furthermore, one or more genes on the Q chromosome of N. tabacum were absolutely responsible for hybrid lethality, suggesting that many species of section Suaveolentes share the same factor that triggers hybrid lethality by interaction with the genes on the Q chromosome. Exceptionally, only one wild species, N. fragrans, produced 100 % viable hybrids after crossing with N. tabacum, suggesting that N. fragrans has no factor triggering hybrid lethality.     

Expression and function of inducible co-stimulator in patients with systemic lupus erythematosus: possible involvement in excessive interferon-gamma and anti-double-stranded DNA antibody production

Inducible co-stimulator (ICOS) is the third member of the CD28/cytotoxic T-lymphocyte associated antigen-4 family and is involved in the proliferation and activation of T cells. A detailed functional analysis of ICOS on peripheral blood T cells from patients with systemic lupus erythematosus (SLE) has not yet been reported. In the present study we developed a fully human anti-human ICOS mAb (JTA009) with high avidity and investigated the immunopathological roles of ICOS in SLE. JTA009 exhibited higher avidity for ICOS than a previously reported mAb, namely SA12. Using JTA009, ICOS was detected in a substantial proportion of unstimulated peripheral blood T cells from both normal control individuals and patients with SLE. In CD4+CD45RO+ T cells from peripheral blood, the percentage of ICOS+ cells and mean fluorescence intensity with JTA009 were significantly higher in active SLE than in inactive SLE or in normal control individuals. JTA009 co-stimulated peripheral blood T cells in the presence of suboptimal concentrations of anti-CD3 mAb. Median values of [3H]thymidine incorporation were higher in SLE T cells with ICOS co-stimulation than in normal T cells, and the difference between inactive SLE patients and normal control individuals achieved statistical significance. ICOS co-stimulation significantly increased the production of IFN-gamma, IL-4 and IL-10 in both SLE and normal T cells. IFN-gamma in the culture supernatants of both active and inactive SLE T cells with ICOS co-stimulation was significantly higher than in normal control T cells. Finally, SLE T cells with ICOS co-stimulation selectively and significantly enhanced the production of IgG anti-double-stranded DNA antibodies by autologous B cells. These findings suggest that ICOS is involved in abnormal T cell activation in SLE, and that blockade of the interaction between ICOS and its receptor may have therapeutic value in the treatment of this intractable disease.     

Physical and functional interaction of Fyn tyrosine kinase with a brain-enriched Rho GTPase-activating protein TCGAP

Fyn, a member of the Src family of tyrosine kinases, is implicated in both brain development and adult brain function. In the present study, we identified a Rho GTPase-activating protein (GAP), TCGAP (Tc10/Cdc42 GTPase-activating protein), as a novel Fyn substrate. TCGAP interacted with Fyn and was phosphorylated by Fyn, with Tyr-406 in the GAP domain as a major Fyn-mediated phosphorylation site. Fyn suppressed the GAP activity of wild-type TCGAP but not the Y406F mutant of TCGAP in a phosphorylation-dependent manner, suggesting that Fyn-mediated Tyr-406 phosphorylation negatively regulated the TCGAP activity. In situ hybridization analyses showed that TCGAP mRNA was expressed prominently in both immature and adult mouse brain, with high levels in cortex, corpus striatum, hippocampus, and olfactory bulb. Overexpression of wild-type TCGAP in PC12 cells suppressed nerve growth factor-induced neurite outgrowth, whereas a GAP-defective mutant of TCGAP enhanced the neurite outgrowth. Nerve growth factor enhanced tyrosine phosphorylation of TCGAP through activation of Src family kinases. These results suggest that TCGAP is involved in Fyn-mediated regulation of axon and dendrite outgrowth.     

Angelmarin, a novel anti-cancer agent able to eliminate the tolerance of cancer cells to nutrient starvation

The CH(2)Cl(2)-soluble extract of Angelica pubescens was found to kill PANC-1 cancer cells preferentially under nutrition starvation at a concentration of 50 microg/ml, with virtually no cytotoxicity under nutrient-rich conditions. Further bioassay-guided fractionation and isolation led to the isolation of a novel compound named angelmarin as the primary compound responsible for the preferential cytotoxicity; the compound exhibited 100% preferential cytotoxicity against PANC-1 cells at a concentration of 0.01 microg/ml.     

CYP3A4 and CYP2D6 inhibitory activities of Indonesian medicinal plants

Thirty samples of Indonesian medicinal plants were analyzed for their capacity to inhibit in vitro metabolism by human cytochrome P450 3A4 (CYP3A4) and CYP2D6 with a radiometric assay. The MeOH-soluble fractions of 25 samples, prepared from water extracts, demonstrated inhibitory activity more than 50% on the metabolism mediated by CYP3A4, and 21 samples on the metabolism mediated by CYP2D6. Among the MeOH-soluble fractions, Piper nigrum leaf showed the highest inhibitory activity against CYP3A4 (91.7%), and Punica granatum against CYP2D6 (98.1%). The water extracts of which MeOH-soluble fraction showed inhibitory activity more than 70% were fractionated with EtOAc. From the EtOAc-soluble fractions, Curcuma heyneana (67.0%), Pi. cubeba (75.0%), Pi. nigrum fruit (84.0%), Pi. nigrum leaf (85.8%), and Zingiber aromaticum (75.3%) demonstrated inhibitory activity more than 50% on the metabolism mediated by CYP3A4, but only Pi. nigrum fruit (72.8%) and Pi. nigrum leaf (69.1%) showed strong inhibitory activity against CYP2D6. For samples that showed more than 70% inhibition, their IC(50) values were determined. The most potent inhibitory activity against CYP3A4 (IC(50) value of 25 microg/ml) was found for the extract of Pi. nigrum leaf, while that of Catharanthus roseus showed the most potent inhibitory effect against CYP2D6 (IC(50) value of 11 microg/ml). These results should indicate once more the possibility of potential medicinal plant-drug interactions.     

Carcinogenic 3-nitrobenzanthrone induces oxidative damage to isolated and cellular DNA

3-Nitrobenzanthrone (3-NBA) is an extremely potent mutagen in diesel exhaust. It is a lung carcinogen to rats, and therefore a suspected carcinogen to human. In order to clarify the mechanism of carcinogenicity of 3-NBA, we investigated oxidative DNA damage by N-hydroxy-3-aminobenzanthrone (N-OH-ABA), a metabolite of 3-NBA, using 32P-labeled DNA fragments from the human p53 tumor-suppressor gene. N-OH-ABA caused Cu(II)-mediated DNA damage, and endogenous reductant NADH dramatically enhanced this process. Catalase and a Cu(I)-specific chelator decreased DNA damage, suggesting the involvement of hydrogen peroxide (H2O2) and Cu(I). N-OH-ABA induced DNA damage at cytosine and guanine residues of ACG sequence complementary to codon 273, a well-known hot spot of the p53 gene. N-OH-ABA dose dependently induced 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) formation in the presence of Cu(II) and NADH. Treatment with N-OH-ABA increased amounts of 8-oxodG in HL-60 cells compared to the H2O2-resistant clone HP100, supporting the involvement of H2O2. The present study has demonstrated that the N-hydroxy metabolite of 3-NBA induces oxidative DNA damage through H2O2 in both a cell-free system and cultured human cells. We conclude that oxidative DNA damage may play an important role in the carcinogenic process of 3-NBA in addition to previously reported DNA adduct formation.     

Methylene blue protection against hypoxic injury in primary cultures of rat hepatocyte monolayers

Mitochondrial respiration is inhibited in cells exposed to hypoxia, and the oxidation of NADH to NAD(+) is blocked. As a result, oxidation reactions requiring NAD(+) are blocked, disrupting cellular metabolism. We studied the influence of methylene blue, which oxidizes NADH, on hypoxic damage to primary cultures of rat hepatocyte monolayers. During hypoxic treatment of hepatocytes, aspartate aminotransferase leaked out of the cells into the culture medium. However, addition of methylene blue to the medium repressed the hypoxic leakage of the enzyme. The exposure of hepatocytes to hypoxia decreased the acetoacetate/beta-hydroxybutyrate ratio which reflects the redox state of the cell. The level of the acetoacetate/beta-hydroxybutyrate ratio in hypoxic cells was increased by the addition of methylene blue. These results suggest that methylene blue protects against hypoxic injury due to its oxidation of NADH.