Numerous Genes (numerous + gene)

Distribution by Scientific Domains

Selected Abstracts

Metagenomic approach studying the taxonomic and functional diversity of the bacterial community in a mesotrophic lake (Lac du Bourget , France)

Didier Debroas
Summary The main goals of this work were to identify the metabolic pathways of the bacterial community in a lacustrine ecosystem and to establish links between taxonomic composition and the relative abundances of these metabolic pathways. For this purpose, we analysed a 16S rRNA gene library obtained by gene amplification together with a sequence library of both insert ends on c. 7700 fosmids. Whatever the library used, Actinobacteria was the most abundant bacterial group, followed by Proteobacteria and Bacteroidetes. Specific aquatic clades such as acI and acIV (Actinobacteria) or LD12 and GOBB-C201 (Alphaproteobacteria) were found in both libraries. From comparative analysis of metagenomic libraries, the metagenome of this lake was characterized by overrepresentation of genes involved in the degradation of xenobiotics mainly associated with Alphaproteobacteria. Actinobacteria were mainly related to metabolic pathways involved in nucleotide metabolism, cofactors, vitamins, energy, replication and repair. Betaproteobacteria appeared to be characterized by the presence of numerous genes implicated in environmental information processing (membrane transport and signal transduction) whereas glycan and carbohydrate metabolism pathways were overrepresented in Bacteroidetes. These results prompted us to propose hypotheses on the ecological role of these bacterial classes in lacustrine ecosystems. [source]

Transgenic Animals in Cardiovascular Disease Research

Michael Bader
Worldwide, the highest morbidity and mortality results from such cardiovascular diseases as hypertension, myocardial infarction, cardiac and renal failure, as well as stroke. Since the cardiovascular system and its regulation is quite complex, study of these disorders has been grossly limited to whole organism models. As a result, in recent years, transgenic technology has played a significant role in the discovery of specific gene products for cardiovascular regulation and disease aetiology. Genetic manipulation in rats and mice has altered the expression of numerous genes. In this review, some of the important new genetically modified animals (i.e. transgenic models) with alterations in hormone and second messenger systems involved in cardiovascular regulation are summarized. [source]

The Impact of Interferon Gamma Receptor Expression on the Mechanism of Escape From Host Immune Surveillance in Hepatocellular Carcinoma

HEPATOLOGY, Issue 3 2000
Mitsuo Nagao M.D.
Interferon gamma (IFN-,) plays an important role in host defense mechanism and participates in the progression of chronic liver disease. IFN-, exerts its pleiotrophic effects by transcriptional regulation of expression of numerous genes, such as major histocompatibility complex (MHC) class I and Fas, through interaction with IFN-, receptor (IFN-,-R). Although hepatocytes in normal liver express weak or no IFN-,-R, those in acute and chronic liver disease up-regulate its expression. A study using IFN-,-R ,-chain knock-out mice revealed the actions of IFN-, on tumor cells as an extrinsic tumor-suppressor mechanism. However, it is unclear whether or how hepatocellular carcinoma (HCC) blocks the signal transduction of IFN-, to evade host immune surveillance. We examined the expression of IFN-,-R and IFN-,,inducible genes in 44 cases with HCC using real-time reverse-transcriptase polymerase chain reaction (RT-PCR) and immunohistochemistry. In noncancerous liver tissues (n = 38), IFN-,-R expression on the cell surface was up-regulated in 27 cases. In IFN-,-R,negative cases (n = 15), tumor size was larger (P = .032), serum ,-fetoprotein (AFP) level was higher (P = .001), intrahepatic and extrahepatic metastasis was more common (P = .044 and .013, respectively), and Ki-67 labeling index (LI) was higher (P = .041), compared with IFN-,-R,positive cases. Accordingly, the evasion mechanism may play an important role in progression, especially metastasis, in HCC. The significant correlation between the status of IFN-,-R and the expression of Fas and MHC implies that the loss of IFN-,-R might contribute to the mechanism of escape from host immune rejection in HCC. [source]

MYCN regulates oncogenic MicroRNAs in neuroblastoma

Johannes H. Schulte
Abstract MYCN amplification is a common feature of aggressive tumour biology in neuroblastoma. The MYCN transcription factor has been demonstrated to induce or repress expression of numerous genes. MicroRNAs (miRNA) are a recently discovered class of short RNAs that repress translation and promote mRNA degradation by sequence-specific interaction with mRNA. Here, we sought to analyse the role of MYCN in regulation of miRNA expression. Using a miRNA microarray containing 384 different miRNAs and a set of 160 miRNA real-time PCR assays to validate the microarray results, 7 miRNAs were identified that are induced by MYCN in vitro and are upregulated in primary neuroblastomas with MYCN amplification. Three of the seven miRNAs belong to the miR-106a and miR-17 clusters, which have previously been shown to be regulated by c-Myc. The miR-17,92 polycistron also acts as an oncogene in haematopoietic progenitor cells. We show here that miR-221 is also induced by MYCN in neuroblastoma. Previous studies have reported miR-221 to be overexpressed in several other cancer entities, but its regulation has never before been associated with Myc. We present evidence of miRNA dysregulation in neuroblastoma. Additionally, we report miRNA induction to be a new mechanism of gene expression downregulation by MYCN. 2007 Wiley-Liss, Inc. [source]

Condition-adapted stress and longevity gene regulation by Caenorhabditis elegans SKN-1/Nrf

AGING CELL, Issue 5 2009
Riva P. Oliveira
Summary Studies in model organisms have identified regulatory processes that profoundly influence aging, many of which modulate resistance against environmental or metabolic stresses. In Caenorhabditis elegans, the transcription regulator SKN-1 is important for oxidative stress resistance and acts in multiple longevity pathways. SKN-1 is the ortholog of mammalian Nrf proteins, which induce Phase 2 detoxification genes in response to stress. Phase 2 enzymes defend against oxygen radicals and conjugate electrophiles that are produced by Phase 1 detoxification enzymes, which metabolize lipophilic compounds. Here, we have used expression profiling to identify genes and processes that are regulated by SKN-1 under normal and stress,response conditions. Under nonstressed conditions SKN-1 upregulates numerous genes involved in detoxification, cellular repair, and other functions, and downregulates a set of genes that reduce stress resistance and lifespan. Many of these genes appear to be direct SKN-1 targets, based upon presence of predicted SKN-binding sites in their promoters. The metalloid sodium arsenite induces skn-1- dependent activation of certain detoxification gene groups, including some that were not SKN-1-upregulated under normal conditions. An organic peroxide also triggers induction of a discrete Phase 2 gene set, but additionally stimulates a broad SKN-1-independent response. We conclude that under normal conditions SKN-1 has a wide range of functions in detoxification and other processes, including modulating mechanisms that reduce lifespan. In response to stress, SKN-1 and other regulators tailor transcription programs to meet the challenge at hand. Our findings reveal striking complexity in SKN-1 functions and the regulation of systemic detoxification defenses. [source]

Identification and Regulation of Genes from a Biocontrol Strain of Fusarium oxysporum

D. R. Fravel
Abstract Differential display with three time points revealed that thiram altered expression of numerous genes in the biocontrol fungus Fusarium oxysporum CS-20. Of the 101 bands purified from the differential display gel, 86 were successfully cloned, and 64 sequenced. Based on nucleic acid sequences, homology to known products was found using BLASTn for 26 sequences and homology to hypothetical proteins was found for six sequences, also from Gibberella zeae. One band (BM1 24-1) showed homology to an ABC transporter from three different fungi. Because of its association with detoxification functions, the ABC transporter was selected for further study. Mycelia of CS-20 were exposed to 25 ,g active ingredient (a.i.) thiram in liquid culture for various times from 0 to 8 h. Quantitative real-time PCR was used to evaluate gene expression. At 30 min after treatment with thiram, the ABC transporter was upregulated 20- to 25-fold relative to the control treatment. The ABC transporter was upregulated 15-fold at 1 h after treatment and 10-fold at 2 h. At 8 h after treatment, there was no difference between treated and non-treated for expression of the ABC transporter. Transcription of the gene encoding EST BM1 24-1 is induced in response to thiram treatment and may function in providing resistance in F. oxysporum isolate CS-20 to fungicides and other toxins. Tolerance to toxins may be critical to the successful inclusion of CS-20 in disease control strategies in cropping systems. [source]

Expression of intracellular calcium signalling genes in cattle skin during tick infestation

SUMMARY It is widely acknowledged that changes in intracellular calcium ion (Ca2+) concentration provide dynamic signals that control a plethora of cellular processes, including triggering and mediating host defence mechanisms. In this study, quantitative real-time PCR was used to analyse gene expression of 14 Ca2+ signalling proteins in skin obtained from high tick-resistant (HR) and low tick-resistant (LR) cattle following artificial challenge with cattle tick (Rhipicephalus (Boophilus) microplus). Up-regulation of numerous genes was observed in both HR and LR skin following tick challenge, however substantially higher transcription activation was found in HR tissue. The elevated expression in HR skin of specific Ca2+ signalling genes such as AHNAK, CASQ, IL2, NFAT2CIP and PLCG1 may be related to host resistance. Our data suggest that Ca2+ and its associated proteins might play an important role in host response to ticks and that further investigation is warranted. [source]