Suchergebnisse

Intro -- Foreword -- Preface -- Contents -- About the Editors -- Carbon and Nitrogen Cycling in Agroecosystems: An Overview -- 1 Introduction -- 2 Soil Organic Carbon (SOC): A Crucial Component of Carbon Cycle -- 3 Carbon-Based GHGs -- 4 SOC Sequestration -- 4.1 SOC and Biodiversity -- 4.2 Importance of Soil Biodiversity -- 4.3 Soil Biodiversity Losses -- 5 SOC Status Under Changing Climate -- 6 Nitrogen Fixation and Reactive Nitrogen -- 6.1 Natural Sources of Fixed Nitrogen -- 6.1.1 Biological Nitrogen Fixation -- 6.1.2 Lightening -- 6.2 Impact of Anthropogenic Activities on N Fixation -- 6.3 Nitrogen Fixation in Cropland -- 7 Overview of Nitrogen Cycle -- 8 Conclusion -- References -- Rhizosphere as Hotspot for Plant-Soil-Microbe Interaction -- 1 Introduction -- 2 Rhizosphere as an Active Network -- 3 Root Exudates Regulating Factors -- 3.1 Abiotic Factors -- 3.1.1 Soil Properties -- 3.1.2 Temperature -- 3.1.3 Light Intensity -- 3.1.4 Nutrient Availability in the Rhizosphere: Nitrogen as Nutrient and Sensor -- 3.2 Biotic Factors -- 3.2.1 Plant/Rhizosphere and Nutrient Use Efficiency -- 3.2.2 Plant Root as Main Trait to Improve NUE -- 4 Microbial Selection by Plants -- 5 Plant-Microbe Interaction -- 5.1 N2-Fixing Bacteria -- 5.2 Plant Growth-Promoting Bacteria (PGPR) -- 5.3 Mycorrhizal Fungi -- 5.4 Pathogenic Microorganisms -- 6 Concluding Remarks and Future Applications -- References -- Biochar and Organic Amendments for Sustainable Soil Carbon and Soil Health -- 1 Introduction -- 2 Biochar -- 2.1 What Is Biochar? -- 2.2 Preparation and Characterization -- 2.2.1 Biochar Preparation and Production -- 2.2.2 Chemical Characters of Biochar -- 2.2.3 Biochar Potential as a Soil Amendment -- 2.2.4 The Sorption Capacity of Biochar -- 2.2.5 Remediation of Polluted Soil for Improving Soil Fertility -- 3 Organic Amendments.

Abstract
Transcriptomic analyses using high-throughput methods have revealed abundant antisense transcription in bacteria. Antisense transcription is often due to the overlap of mRNAs with long 5′ or 3′ regions that extend beyond the coding sequence. In addition, antisense RNAs that do not contain any coding sequence are also observed. Nostoc sp. PCC 7120 is a filamentous cyanobacterium that, under nitrogen limitation, behaves as a multicellular organism with division of labor among two different cell types that depend on each other, the vegetative CO2-fixing cells and the nitrogen-fixing heterocysts. The differentiation of heterocysts depends on the global nitrogen regulator NtcA and requires the specific regulator HetR. To identify antisense RNAs potentially involved in heterocyst differentiation, we assembled the Nostoc transcriptome using RNA-seq analysis of cells subjected to nitrogen limitation (9 or 24 h after nitrogen removal) in combination with a genome-wide set of transcriptional start sites and a prediction of transcriptional terminators. Our analysis resulted in the definition of a transcriptional map that includes >4,000 transcripts, 65% of which contain regions in antisense orientation to other transcripts. In addition to overlapping mRNAs, we identified nitrogen-regulated noncoding antisense RNAs transcribed from NtcA- or HetR-dependent promoters. As an example of this last category, we further analyzed an antisense (as_gltA) of the gene-encoding citrate synthase and showed that transcription of as_gltA takes place specifically in heterocysts. Since the overexpression of as_gltA reduces citrate synthase activity, this antisense RNA could eventually contribute to the metabolic remodeling that occurs during the differentiation of vegetative cells into heterocysts.