More than a carbon economy: nutrient trade and ecological sustainability in facultative arbuscular mycorrhizal symbioses

Symbiosis is well recognized as a major force in plant ecology and evolution. However, there is considerable uncertainty about the functional, ecological and evolutionary benefits of the very widespread facultative arbuscular mycorrhizal (AM) associations, in which the plants can grow and reproduce whether or not they are colonized by AM fungi. Here we address the significance of new research findings that are overturning conventional views that facultative AM associations can be likened to parasitic fungus–plant associations. Specifically, we address the occurrence and importance of phosphate uptake via AM fungi that does not result in increases in total phosphorus (P) uptake or in plant growth, and possible signalling between AM fungi and plants that can result in plant growth depressions even when fungal colonization remains very low. We conclude that, depending on the individual AM fungi that are present, the role of facultative AM associations in the field, especially in relation to plant competition, may be much more subtle than has been previously envisaged.     

Brief psychotherapy in medical practice. Keys to success.

For physicians faced with helping their patients cope with difficult medical problems, solution-oriented psychotherapeutic techniques provide brief, effective interventions. These approaches offer "skeleton keys" that can be used in a broad patient population. They include clarifying the meaning of the medical illness, therapeutic reframing, projection of the problem, role reversal, and face-saving techniques.     

Bacterial symbioses. Predation and mutually beneficial associations.

The endosymbiotic theory, which has proved to explain the origin of mitochondria and chloroplasts, also posits the origin of nucleus and other cellular organelles that could have derived from ancient relationships among bacteria. It seems that predation might have been a prerequisite to the establishment of symbiosis as a source of evolutionary novelty. This review describes current different examples of bacteria able not only to attack and degrade other bacteria, but also to establish stable symbiotic relationships with different eukaryotic organisms.     

从生理特点浅析昆虫繁盛原因

昆虫成为地球上数量最多、最为成功的一类动物 ,要归功于它们在长期进化过程中所形成的特点。该文从生理学的角度 ,分析了躯体大小、外骨骼、飞行、气管系统、变态、生殖、神经系统、食性等因素对昆虫繁盛的作用。