Characterization and monitoring of selected rhizobial strains isolated from tree legumes in Thailand

Tree legume rhizobia were isolated from five tree legumes; Acacia auriculaformis Cunn., A. mangium Willd., Milletia leucantha Kurz., Pterocarpus indicus Willd., and Xylia xylocarpa Taub. grown in Thailand.Forty four highly effective rhizobial strains were selected on the basis of nitrogenase activity, number of nodules and plant biomass. The selected strains were characterized in both terms of physiology andgenetics. Most of the strains are slow grower and able to nodulate cowpea rather than soybean. In addition, IAA production could be detected only from few strains. When almost complete 16S rRNAsequences were analysed, the results indicated that most of the selected strains most likely belong to Bradyrhizobium elkanii and Bradyrhizobium sp. except strains AA67 and PT59 which most likely belong to B. japonicum. The nodule occupancy of selected strains in forest soil condition was investigated by using GUS reporter gene. The nodule occupancy is in the range of 63 - 100%. This suggests theappropriate strains should be produced as inoculum for further application in reforestation programmes in Thailand

Does physical activity reduce risk for Alzheimer’s disease through interaction with the stress neuroendocrine system?

Lack of physical activity (PA) is a risk factor for Alzheimer's disease (AD) and PA interventions are believed to provide an effective non-pharmacological approach for attenuating the symptoms of this disease. However, the mechanism of action of these positive effects is currently unknown. It is possible that the benefits may be at least partially mediated by effects on the neuroendocrine stress system. Chronic stress can lead to dysfunction of the hypothalamic pituitary adrenal (HPA) axis, leading to aberrant basal and circadian patterns of cortisol secretion and a cascade of negative downstream events. These factors have been linked not only to reduced cognitive function in the non-demented but also increased levels of Amyloid β plaques and protein Tau "tangles" (the neuropathological hallmarks of AD) in mouse models of this disease. However, there is evidence that PA can have restorative effects on the stress neuroendocrine system and related risk factors relevant to AD. We explore the possibility that PA can positively impact upon AD by restoring normative HPA axis function, with consequent downstream effects upon underlying neuropathology and associated cognitive function. We conclude with suggestions for future research to test this hypothesis in patients with AD