The genetics of symbiotic nitrogen fixation: comparative genomics of 14 Rhizobia Strains by resolution of protein clusters.

The symbiotic relationship between legumes and nitrogen fixing bacteria is critical for agriculture, as it may have profound impacts on lowering costs for farmers, on land sustainability, on soil quality, and on mitigation of greenhouse gas emissions. However, despite the importance of the symbioses to the global nitrogen cycling balance, very few rhizobial genomes have been sequenced so far, although there are some ongoing efforts in sequencing elite strains. In this study, the genomes of fourteen selected strains of the order Rhizobiales, all previously fully sequenced and annotated, were compared to assess differences between the strains and to investigate the feasibility of defining a core ?symbiome??the essential genes required by all rhizobia for nodulation and nitrogen fixation. Comparison of these whole genomes has revealed valuable information, such as several events of lateral gene transfer, particularly in the symbiotic plasmids and genomic islands that have contributed to a better understanding of the evolution of contrasting symbioses. Unique genes were also identified, as well as omissions of symbiotic genes that were expected to be found. Protein comparisons have also allowed the identification of a variety of similarities and differences in several groups of genes, including those involved in nodulation, nitrogen fixation, production of exopolysaccharides, Type I to Type VI secretion systems, among others, and identifying some key genes that could be related to host specificity and/or a better saprophytic ability. However, while several significant differences in the type and number of proteins were observed, the evidence presented suggests no simple core symbiome exists. A more abstract systems biology concept of nitrogen fixing symbiosis may be required. The results have also highlighted that comparative genomics represents a valuable tool for capturing specificities and generalities of each genome.bitstream/item/74069/1/ID-34062.pd

Summary of Medic-Rhizobium field experiments 1983 – 1984

Trials 83ME9, 83ME87, 82ME22, 82ME22A, 82ME23. Method. Comment

Summary of Medic-Rhizobium field experiments

83ME9 - Nutrition of R. meliloti in acid soil. - Meaningful results only available in 1984/85 Summary of Medic-Rhizobium Field Experiments 1983/84. 83ME87 - Effect of pH of culture conditions on survival in, and colonisation of, an acid soil by R. meliloti. - Meaningful results available 1984/85. (82ME22, 82ME22A, 82ME23) Survival and colonisation of acid soils by 18 strains of R. meliloti in association with 6 Medicago hosts. - Results discussed in this summary

Summary of Rhibozium field experiments in 1988

87M11, 87H12, 88KA77, 88ME97, 88GE32, 88ME98, 88GE33A, 88GE33B, 88KA86, 88ME86. Title, aim, background, treatments, tables, results, discussion, conclusions

Summary of Rhizobium experiments.

Rotation trials, 84ME32, 84ME24, 84N18, 84M18, 85KA58. Cross row trials, 85M28. One year trials, 86M41, 86M42. On-going trials, 86M58, 85KA64, 86V3, 86AL. 84WH24

Domestic ventilation rates, indoor humidity and dust mite allergens : are our homes causing the asthma pandemic?

This paper is concerned with historical changes in domestic ventilation rates, relative humidity and the associated risk of house dust mite colonization. A controlled trial evaluated allergen and water vapour control measures on the level of house dust mite (HDM) Der p1 allergen and indoor humidity, concurrently with changes in lung function in 54 subjects who completed the protocol. Mechanical heat recovery ventilation units significantly reduced moisture content in the active group, while HDM allergen reservoirs in carpets and beds were reduced by circa 96%. Self reported health status confirmed a significant clinical improvement in the active group. The study can form the basis for assessing minimum winter ventilation rates that can suppress RH below the critical ambient equilibrium humidity of 60% and thus inhibit dust mite colonization and activity in temperate and maritime in' uenced climatic regions