Transcript levels of the nuclear-encoded respiratory genes in rice decrease by oxygen deprivation: evidence for involvement of calcium in expression of the alternative oxidase 1a gene

AbstractWe investigated the effect of oxygen on the expressions of respiratory genes encoded in the nuclear and mitochondrial genomes of rice (Oryza sativa L.). Hypoxic treatment decreased the transcript levels of nuclear-encoded, but not mitochondrial-encoded respiratory genes. The effects of ruthenium red (an inhibitor of Ca2+ fluxes from organelles) and/or CaCl2 on plants under hypoxic conditions suggested that Ca2+ is a physiological transducer of a low-oxygen signaling pathway for expression of the alternative oxidase 1a gene (AOX1a), but not for expressions of genes involved in the cytochrome respiratory pathway, in rice

Transfer of rice mitochondrial ribosomal protein L6 gene to the nucleus: acquisition of the 5'-untranslated region via a transposable element

<p>Abstract</p> <p>Background</p> <p>The mitochondria of contemporary organisms contain fewer genes than the ancestral bacteria are predicted to have contained. Because most of the mitochondrial proteins are encoded in the nucleus, the genes would have been transferred from the mitochondrion to the nucleus at some stage of evolution and they must have acquired cis-regulatory elements compatible with eukaryotic gene expression. However, most of such processes remain unknown.</p> <p>Results</p> <p>The ribosomal protein L6 gene (<it>rpl6</it>) has been lost in presently-known angiosperm mitochondrial genomes. We found that each of the two rice <it>rpl6 </it>genes (<it>OsRpl6-1 </it>and <it>OsRpl6-2</it>) has an intron in an identical position within the 5'-untranslated region (UTR), which suggests a duplication of the <it>rpl6 </it>gene after its transfer to the nucleus. Each of the predicted RPL6 proteins lacks an N-terminal extension as a mitochondrial targeting signal. Transient assays using green fluorescent protein indicated that their mature N-terminal coding regions contain the mitochondrial targeting information. Reverse transcription-PCR analysis showed that <it>OsRpl6-2 </it>expresses considerably fewer transcripts than <it>OsRpl6-1</it>. This might be the result of differences in promoter regions because the 5'-noncoding regions of the two <it>rpl6 </it>genes differ at a point close to the center of the intron. There are several sequences homologous to the region around the 5'-UTR of <it>OsRpl6-1 </it>in the rice genome. These sequences have characteristics similar to those of the transposable elements (TE) belonging to the <it>PIF</it>/Harbinger superfamily.</p> <p>Conclusion</p> <p>The above evidences suggest a novel mechanism in which the 5'-UTR of the transferred mitochondrial gene was acquired via a TE. Since the 5'-UTRs and introns within the 5'-UTRs often contain transcriptional and posttranscriptional cis-elements, the transferred rice mitochondrial <it>rpl6 </it>gene may have acquired its cis-element from a TE.</p

Clarithromycin Suppresses Human Respiratory Syncytial Virus Infection-Induced Streptococcus pneumoniae Adhesion and Cytokine Production in a Pulmonary Epithelial Cell Line

Human respiratory syncytial virus (RSV) sometimes causes acute and severe lower respiratory tract illness in infants and young children. RSV strongly upregulates proinflammatory cytokines and the platelet-activating factor (PAF) receptor, which is a receptor for Streptococcus pneumoniae, in the pulmonary epithelial cell line A549. Clarithromycin (CAM), which is an antimicrobial agent and is also known as an immunomodulator, significantly suppressed RSV-induced production of interleukin-6, interleukin-8, and regulated on activation, normal T-cell expressed and secreted (RANTES). CAM also suppressed RSV-induced PAF receptor expression and adhesion of fluorescein-labeled S. pneumoniae cells to A549 cells. The RSV-induced S. pneumoniae adhesion was thought to be mediated by the host cell's PAF receptor. CAM, which exhibits antimicrobial and immunomodulatory activities, was found in this study to suppress the RSV-induced adhesion of respiratory disease-causing bacteria, S. pneumoniae, to host cells. Thus, CAM might suppress immunological disorders and prevent secondary bacterial infections during RSV infection

A novel plant nuclear gene encoding chloroplast ribosomal protein S9 has a transit peptide related to that of rice chloroplast ribosomal protein L12

AbstractWe have cloned a novel nuclear gene for a ribosomal protein of rice and Arabidopsis that is like the bacterial ribosomal protein S9. To determine the subcellular localization of the gene product, we fused the N-terminal region and green fluorescent protein and expressed it transiently in rice seedlings. Localized fluorescence was detectable only in chloroplasts, indicating that this nuclear gene encodes chloroplast ribosomal protein S9. The N-terminal region of rice ribosomal protein S9 was found to have a high sequence similarity to the transit peptide region of the rice chloroplast ribosomal protein L12, suggesting that these transit peptides have a common lineage

Selective labeling of a single organelle by using two-photon conversion of a photoconvertible fluorescent protein

SPIE BiOS, 2008, San Jose, California, United StatesWataru Watanabe, Tomoko Shimada, Sachihiro Matsunaga, Daisuke Kurihara, Shin-ichi Arimura, Nobuhiro Tsutsumi, Kiichi Fukui, Kazuyoshi Itoh, "Selective labeling of a single organelle by using two-photon conversion of a photoconvertible fluorescent protein," Proc. SPIE 6860, Multiphoton Microscopy in the Biomedical Sciences VIII, 68601B (15 February 2008); https://doi.org/10.1117/12.768745

Root Cortex Provides a Venue for Gas-Space Formation and Is Essential for Plant Adaptation to Waterlogging

Lysigenous aerenchyma, which develops by death and subsequent lysis of the cortical cells in roots, is essential for internal long-distance oxygen transport from shoot base to root tips of plants in waterlogged soil. Although many studies focus on the amounts of aerenchyma in roots, significance of the size of the root cortex in which aerenchyma forms has received less research attention. In the present study, we evaluated the cross-sectional area of each root tissue in adventitious roots of upland crops, wheat (Triticum aestivum) and maize (Zea mays ssp. mays), and the wetland crop, rice (Oryza sativa) under aerated or stagnant deoxygenated conditions; the latter can mimic the changes in gas composition in waterlogged soils. Our analyses revealed that the areas of whole root and cortex of the three species increased under stagnant conditions. In rice roots, cortex to stele ratio (CSR) and aerenchyma to cortex ratio (ACR), which is associated with the areas of gas spaces, were much higher than those in wheat and maize roots, suggesting that these anatomical features are essential for a high capacity for oxygen transport along roots. To test this hypothesis, rates of radial oxygen loss (ROL), which is the diffusive flux of oxygen from within a root to the external medium, from thick and thin adventitious roots of rice were measured using a cylindrical (root-sleeving) oxygen electrode, for plants with shoots in air and roots in an oxygen-free medium. As expected, the rate of ROL from thick roots, which have larger cortex and aerenchyma areas, was higher than that of thin roots. The rate of ROL was highest at the apical part of rice roots, where aerenchyma was hardly detected, but at which cuboidal cell arrangement in the cortex provides tissue porosity. We conclude that high CSR in combination with large root diameter is a feature which promotes oxygen transport from shoot base to root tips of plants. Moreover, we propose that CSR should be a useful quantitative index for the evaluation and improvement of root traits contributing to tolerance of crops to soil waterlogging

NB-LRR-encoding genes conferring susceptibility to organophosphate pesticides in sorghum

Organophosphate is the commonly used pesticide to control pest outbreak, such as those by aphids in many crops. Despite its wide use, however, necrotic lesion and/or cell death following the application of organophosphate pesticides has been reported to occur in several species. To understand this phenomenon, called organophosphate pesticide sensitivity (OPS) in sorghum, we conducted QTL analysis in a recombinant inbred line derived from the Japanese cultivar NOG, which exhibits OPS. Mapping OPS in this population identified a prominent QTL on chromosome 5, which corresponded to Organophosphate-Sensitive Reaction (OSR) reported previously in other mapping populations. The OSR locus included a cluster of three genes potentially encoding nucleotide-binding leucine-rich repeat (NB-LRR, NLR) proteins, among which NLR-C was considered to be responsible for OPS in a dominant fashion. NLR-C was functional in NOG, whereas the other resistant parent, BTx623, had a null mutation caused by the deletion of promoter sequences. Our finding of OSR as a dominant trait is important not only in understanding the diversified role of NB-LRR proteins in cereals but also in securing sorghum breeding free from OPS

Early expression of serum CCL8 closely correlates to non-relapse mortality after allogeneic hematopoietic stem cell transplantation

To explore the role of Chemokine (C-C motif) ligand 8 (CCL8) as a potential biomarker for acute graft-versus-host disease (aGVHD), we retrospectively analyzed the sera and clinical course of 31 patients with grade II?IV aGVHD. No deaths occurred in the ten patients with serum CCL8 concentrations less than 213 pg/mL, whereas 11 of the 21 patients with more than 213 pg/mL died within 180 days post-transplantation. This landmark analysis revealed a significantly lower urvival rate of patients with a CCL8 serum concentration greater than 213 pg/mL. Thus, elevated serum CCL8 concentration before day 100 post-transplantation may predict aGVHD prognosi

Peroxisome proliferator-activated receptor α (PPARα) mRNA expression in human hepatocellular carcinoma tissue and non-cancerous liver tissue

<p>Abstract</p> <p>Background</p> <p>Peroxisome proliferator-activated receptor α (PPARα) regulates lipid metabolism in the liver. It is unclear, however, how this receptor changes in liver cancer tissue. On the other hand, mouse carcinogenicity studies showed that PPARα is necessary for the development of liver cancer induced by peroxisome proliferators, and the relationship between PPARα and the development of liver cancer have been the focus of considerable attention. There have been no reports, however, demonstrating that PPARα is involved in the development of human liver cancer.</p> <p>Methods</p> <p>The subjects were 10 patients who underwent hepatectomy for hepatocellular carcinoma. We assessed the expression of PPARα mRNA in human hepatocellular carcinoma tissue and non-cancerous tissue, as well as the expression of target genes of PPARα, carnitine palmitoyltransferase 1A and cyclin D1 mRNAs. We also evaluated glyceraldehyde 3-phosphate dehydrogenase, a key enzyme in the glycolytic system.</p> <p>Results</p> <p>The amounts of PPARα, carnitine palmitoyltransferase 1A and glyceraldehyde 3-phosphate dehydrogenase mRNA in cancerous sections were significantly increased compared to those in non-cancerous sections. The level of cyclin D1 mRNA tends to be higher in cancerous than non-cancerous sections. Although there was a significant correlation between the levels of PPARα mRNA and cyclin D1 mRNA in both sections, however the correlation was higher in cancerous sections.</p> <p>Conclusion</p> <p>The present investigation indicated increased expression of PPARα mRNA and mRNAs for PPARα target genes in human hepatocellular carcinoma. These results might be associated with its carcinogenesis and characteristic features of energy production.</p

Separated Transcriptomes of Male Gametophyte and Tapetum in Rice: Validity of a Laser Microdissection (LM) Microarray

In flowering plants, the male gametophyte, the pollen, develops in the anther. Complex patterns of gene expression in both the gametophytic and sporophytic tissues of the anther regulate this process. The gene expression profiles of the microspore/pollen and the sporophytic tapetum are of particular interest. In this study, a microarray technique combined with laser microdissection (44K LM-microarray) was developed and used to characterize separately the transcriptomes of the microspore/pollen and tapetum in rice. Expression profiles of 11 known tapetum specific-genes were consistent with previous reports. Based on their spatial and temporal expression patterns, 140 genes which had been previously defined as anther specific were further classified as male gametophyte specific (71 genes, 51%), tapetum-specific (seven genes, 5%) or expressed in both male gametophyte and tapetum (62 genes, 44%). These results indicate that the 44K LM-microarray is a reliable tool to analyze the gene expression profiles of two important cell types in the anther, the microspore/pollen and tapetum