Interaction of mutagenic spermidine-nitrous acid reaction products with uvr- and recA-dependent repair systems in Salmonella.

It has been observed previously that the mutagenic action of nitrous acid may be potentiated by polyamines. We examined the cellular response of two deoxyribonucleic acid repair systems to treatment with spermidine-nitrite reaction products. uvrB- deficient mutants of Salmonella typhimurium LT2 showed enhanced lethal and mutagenic response to the reaction products. Lethal activity was further enhanced in a uvrB recA double mutant, whereas mutagenic activity was not detectable. Dependence of mutagenesis on the recA gene implicates the action of an error-prone repair system in the fixation of a premutagenic lesion as a mutation. From consideration of the substrate characteristics of the two repair systems studied, it is suggested that the deoxyribonucleic acid lesion formed by the reaction products of spermidine and nitrite is an intrastrand cross-link.     

Complete mitochondrial genome sequence of <Emphasis Type="Italic">Cucullaea labiata</Emphasis> (Arcoida: Cucullaeidae) and phylogenetic implications

The complete mitochondrial genome of Cucullaea labiata (Arcoida: Cucullaeidae) was firstly determined in this study in order to better understand the phylogenetic relationship between Cucullaeidae and Arcidae. The C. labiata mitochondrial genome was 25,845 bp in size and contained 12 protein-coding genes, 2 rRNA and 22 tRNA genes. The number and the location of the tRNA genes were different from three Arcidae species (Scapharca broughtonii, Scapharca kagoshimensis and Tegillarca granosa). Gene arrangement also differed dramatically. The length of the non-coding regions was 10,559 bp, in which the largest one (6057 bp) included eight point nine copies of a 659 bp repeat motif. The number of repeated sequences was different in different individuals, similar to the findings from the mitochondrial genome of S. broughtonii and Placopecten magellanicus. One intron was found in cox1 gene both in CL_98 and in CL_99 individuals of C. labiata. The reason why mitochondrial introns are retained so scarcely in bivalve taxa needs further research. Phylogenetic analyses based on 12 concatenated amino acid sequences of protein-coding genes supported Cucullaeidae was the sister group of Arcidae.     

Molecular identification and functional characterization of a Drosophila dual-specificity phosphatase DMKP-4 which is involved in PGN-induced activation of the JNK pathway

MAP (Mitogen-activated protein) kinases play an important role in regulating many critical cellular processes. The inactivation of MAP kinases is always accomplished by a family of dual-specificity phosphatases, termed MAPK phosphatases (MKPs). Here, we have identified a novel MKP-like protein, designated DMKP-4, from the Drosophila genome. DMKP-4 is a protein of 387 amino acids, with a dual-specificity phosphatase (DSP) catalytic domain. Recombinant protein DMKP-4 retains intrinsic phosphatase activity against chromogenic substrate pNPP. Overexpression of DMKP-4 inhibited the activation of ERK, JNK and p38 by H(2)O(2), sorbitol and heat shock in HEK293-T cells, and JNK activation in Drosophila S2 cells under PGN stimuli. "Knockdown" of DMKP-4 expression by RNAi significantly enhanced the PGN-stimulated activation of JNK, but not ERK nor p38. Further study revealed that DMKP-4 interacted specifically with JNK via its DSP domain. Mutation of Cys-126 to serine in the DSP domain of DMKP-4 not only eliminated its interaction with JNK, but also markedly reduced its phosphatase activity. Thus, DMKP-4 is a Drosophila homologue of mammalian MKPs, and may play important roles in the regulation of various developmental processes.     

Vegetation and environment changes inferred from pollen records since 3000 cal. yr BP in Kanas wetland,Xinjiang

Aims Climate change can significantly affect the vegetation worldwide. Thus, paleovegetation and paleoclimate reconstruction should consider the quantitative relationship between modern vegetation and climate. The specific objectives of this study were (i) to assess the influence of environmental variables on pollen assemblages in the Kanas region, (ii) to reconstruct the evolution of vegetation over the past 3000 years using pollen records and (iii) to quantify historical climate change (including mean annual temperature and total annual precipitation) using a weighted averaging partial least squares regression method (WAPLS) applied to fossil pollen data from the Kanas wetland in Xinjiang, China.     

P2Y nucleotide receptor interaction with alpha integrin mediates astrocyte migration

Astrocytes become activated in response to brain injury, as characterized by increased expression of glial fibrillary acidic protein (GFAP) and increased rates of cell migration and proliferation. Damage to brain cells causes the release of cytoplasmic nucleotides, such as ATP and uridine 5'-triphosphate (UTP), ligands for P2 nucleotide receptors. Results in this study with primary rat astrocytes indicate that activation of a G protein-coupled P2Y(2) receptor for ATP and UTP increases GFAP expression and both chemotactic and chemokinetic cell migration. UTP-induced astrocyte migration was inhibited by silencing of P2Y(2) nucleotide receptor (P2Y(2)R) expression with siRNA of P2Y(2)R (P2Y(2)R siRNA). UTP also increased the expression in astrocytes of alpha(V)beta(3/5) integrins that are known to interact directly with the P2Y(2)R to modulate its function. Anti-alpha(V) integrin antibodies prevented UTP-stimulated astrocyte migration, suggesting that P2Y(2)R/alpha(V) interactions mediate the activation of astrocytes by UTP. P2Y(2)R-mediated astrocyte migration required the activation of the phosphatidylinositol-3-kinase (PI3-K)/protein kinase B (Akt) and the mitogen-activated protein kinase/extracellular signal-regulated kinase (MEK/ERK) signaling pathways, responses that also were inhibited by anti-alpha(V) integrin antibody. These results suggest that P2Y(2)Rs and their associated signaling pathways may be important factors regulating astrogliosis in brain disorders.     

MicroRNA-155 Regulates Cell Survival,Growth, and Chemosensitivity by Targeting FOXO3a in Breast Cancer

Breast cancer is the second leading cause of cancer death in women. Despite improvement in treatment over the past few decades, there is an urgent need for development of targeted therapies. miR-155 (microRNA-155) is frequently up-regulated in breast cancer. In this study, we demonstrate the critical role of miR-155 in regulation of cell survival and chemosensitivity through down-regulation of FOXO3a in breast cancer. Ectopic expression of miR-155 induces cell survival and chemoresistance to multiple agents, whereas knockdown of miR-155 renders cells to apoptosis and enhances chemosensitivity. Further, we identified FOXO3a as a direct target of miR-155. Sustained overexpression of miR-155 resulted in repression of FOXO3a protein without changing mRNA levels, and knockdown of miR-155 increases FOXO3a. Introduction of FOXO3a cDNA lacking the 3′-untranslated region abrogates miR-155-induced cell survival and chemoresistance. Finally, inverse correlation between miR-155 and FOXO3a levels were observed in a panel of breast cancer cell lines and tumors. In conclusion, our study reveals a molecular link between miR-155 and FOXO3a and presents evidence that miR-155 is a critical therapeutic target in breast cancer.     

Improved artemisinin accumulation in hairy root cultures of Artemisia annua by (22S, 23S)-homobrassinolide

When (22S, 23S)-homobrassinolide (SSHB) was added at 1 g l^–1 to hairy root cultures of Artemisia annua, the production of artemisinin reached to 14 mg l^–1, an increment of 57% over the control. SSHB treatment led concomitantly to an increased biomass production of 15 g l^–1. A stimulatory activity of SSHB on nucleic acids and soluble protein content in hairy roots was also observed at the growth stage.     

Investigation of the role of endosomal Toll-like receptors in murine collagen-induced arthritis reveals a potential role for TLR7 in disease maintenance

The hepatitis C virus (HCV) is both hepatotropic and lymphotropic, responsible for a great number of hepatic and extrahepatic immune-system disorders that comprise the so-called HCV syndrome. HCV-associated rheumatic diseases are characterized by frequent clinico-serological overlap; therefore, correct classification of individual patients is necessary before therapeutic decisions are made. This is particularly difficult to do, however, because of the coexistence of viral infection and complex autoimmune alterations. In this context, mixed cryoglobulinemia syndrome (MCs) represents the prototype of virus-related autoimmune-lymphoproliferative diseases. MCs can be treated at different levels by means of etiological treatment with antivirals (peg-interferon-alpha plus ribavirin) aimed at HCV eradication and/or pathogenetic/symptomatic treatments directed to both immune-system alterations and the vasculitic process (rituximab, cyclophosphamide, steroids, plasmapheresis, and so on). In clinical practice, the therapeutic strategy should be modulated according to severity/activity of the MCs and possibly tailored to each individual patient's conditions. Cryoglobulinemic skin ulcers may represent a therapeutic challenge, which should be managed by means of both local and systemic treatments. HCV-associated arthritis should be differentiated from the simple comorbidity of HCV infection and classical rheumatoid arthritis. It may be treated with low doses of steroids and/or hydroxychloroquine; the use of biologics (rituximab) may be considered in more severe cases. Primary Sj?gren's syndrome is rarely associated with HCV infection, while sicca syndrome and myalgia are frequently detectable in hepatitis C patients, with or without cryoglobulinemic vasculitis. Other autoimmune rheumatic disorders (poly/dermatomyositis, polyarteritis nodosa, osteosclerosis, fibromyalgia, and so on) have been reported as potentially associated with HCV infection in patient populations from different countries, suggesting the role of genetic and/or environmental co-factors. The therapeutic approach to these disorders should be decided according to each individual patient's evaluation, including hepatic, virological, and immunological findings.