The Existence and Uniqueness of the Solution of a Diusive Predator-Prey Model with Omnivory and General Nonlinear Functional Response

In this work, we consider a three species modified Lesie-Gower food web model with general nonlinear functional response and omnivory which is defined as feeding on more than one trophic level. The carrying capacity of the model is proportional to the population size of the biotic resource plus a const. The main objective of this paper is to investigate the existence and uniqueness of the solution of this model. It is shown that the omnivory has important influence on the existence and uniqueness of the solution of the model.

Geometry and evolution of the ecological niche in plant-associated microbes

The ecological niche of a species can be conceptualized as a volume in multidimensional space, where each dimension describes an abiotic condition or biotic resource. The shape and size of this volume strongly determines interactions among species and influences their global distribution, but the geometry of the niche is poorly understood. Here, we analyse temperature response functions and host plant ranges for hundreds of fungi and oomycetes. We demonstrate that niche specialization is independent on abiotic and biotic axes, that host interactions restrict fundamental niche breadth to form the realized niche, and that both abiotic and biotic niches show limited phylogenetic constraint. Such niche adaptability makes plant pathogens a formidable threat to agriculture and forestry.

Analysis of Life Cycle Environmental Impact of Recycled Aggregate

This study assessed the influence of matter discharged during the production (dry/wet) of recycled aggregate on global warming potential (GWP) and acidification potential (AP), eutrophication potential (EP), ozone depletion potential (ODP), biotic resource depletion potential (ADP), photochemical ozone creation potential (POCP) using the ISO 14044 (LCA) standard. The LCIA of dry recycled aggregate was 2.94 × 10−2 kg-CO2eq/kg, 2.93 × 10−5 kg-SO2eq/kg, 5.44 × 10−6 kg-PO43eq/kg, 4.70 × 10−10 kg-CFC11eq/kg, 1.25 × 10−5 kg-C2H4eq/kg, and 1.60 × 10−5 kg-Antimonyeq/kg, respectively. The environmental impact of recycled aggregate (wet) was up to 16~40% higher compared with recycled aggregate (dry); the amount of energy used by impact crushers while producing wet recycled aggregate was the main cause for this result. The environmental impact of using recycled aggregate was found to be up to twice as high as that of using natural aggregate, largely due to the greater simplicity of production of natural aggregate requiring less energy. However, ADP was approximately 20 times higher in the use of natural aggregate because doing so depletes natural resources, whereas recycled aggregate is recycled from existing construction waste. Among the life cycle impacts assessment of recycled aggregate, GWP was lower than for artificial light-weight aggregate but greater than for slag aggregate.

The drnf1 Gene from the Drought-Adapted Cyanobacterium Nostoc flagelliforme Improved Salt Tolerance in Transgenic Synechocystis and Arabidopsis Plant

Environmental abiotic stresses are limiting factors for less tolerant organisms, including soil plants. Abiotic stress tolerance-associated genes from prokaryotic organisms are supposed to have a bright prospect for transgenic application. The drought-adapted cyanobacterium Nostoc flagelliforme is arising as a valuable prokaryotic biotic resource for gene excavation. In this study, we evaluated the salt-tolerant function and application potential of a candidate gene drnf1 from N. flagelliforme, which contains a P-loop NTPase (nucleoside-triphosphatase) domain, through heterologous expression in two model organisms Synechocystis sp. PCC 6803 and Arabidopsis thaliana. It was found that DRNF1 could confer significant salt tolerance in both transgenic organisms. In salt-stressed transgenic Synechocystis, DRNF1 could enhance the respiration rate; slow-down the accumulation of exopolysaccharides; up-regulate the expression of salt tolerance-related genes at a higher level, such as those related to glucosylglycerol synthesis, Na+/H+ antiport, and sugar metabolism; and maintain a better K+/Na+ homeostasis, as compared to the wild-type strain. These results imply that DRNF1 could facilitate salt tolerance by affecting the respiration metabolism and indirectly regulating the expression of important salt-tolerant genes. Arabidopsis was employed to evaluate the salt tolerance-conferring potential of DRNF1 in plants. The results show that it could enhance the seed germination and shoot growth of transgenic plants under saline conditions. In general, a novel prokaryotic salt-tolerant gene from N. flagelliforme was identified and characterized in this study, enriching the candidate gene pool for genetic engineering in plants.