Deletion of Dcf1 Reduces Amyloid-ß Aggregation and Mitigates Memory Deficits.

BACKGROUND: Alzheimer's disease (AD) is a progressive neurodegenerative disease. One of the pathologies of AD is the accumulation of amyloid-ß (Aß) to form senile plaques, leading to a decline in cognitive ability and a lack of learning and memory. However, the cause leading to Aß aggregation is not well understood. Dendritic cell factor 1 (Dcf1) shows a high expression in the entorhinal cortex neurons and neurofibrillary tangles in AD patients. OBJECTIVE: Our goal is to investigate the effect of Dcf1 on Aß aggregation and memory deficits in AD development. METHODS: The mouse and Drosophila AD model were used to test the expression and aggregation of Aß, senile plaque formation, and pathological changes in cognitive behavior during dcf1 knockout and expression. We finally explored possible drug target effects through intracerebroventricular delivery of Dcf1 antibodies. RESULTS: Deletion of Dcf1 resulted in decreased Aß42 level and deposition, and rescued AMPA Receptor (GluA2) levels in the hippocampus of APP-PS1-AD mice. In Aß42 AD Drosophila, the expression of Dcf1 in Aß42 AD flies aggravated the formation and accumulation of senile plaques, significantly reduced its climbing ability and learning-memory. Data analysis from all 20 donors with and without AD patients aged between 80 and 90 indicated a high-level expression of Dcf1 in the temporal neocortex. Dcf1 contributed to Aß aggregation by UV spectroscopy assay. Intracerebroventricular delivery of Dcf1 antibodies in the hippocampus reduced the area of senile plaques and reversed learning and memory deficits in APP-PS1-AD mice. CONCLUSION: Dcf1 causes Aß-plaque accumulation, inhibiting dcf1 expression could potentially offer therapeutic avenues.

[Response of yield, quality and nitrogen use efficiency to nitrogen fertilizer from mechanical transplanting super japonica rice].

Five super japonica rice cultivars were grown by mechanical transplanting in field and seven N treatments with total N application rate of 0, 150, 187.5, 225, 262.5, 300 and 337.5 kg x hm(-2) respectively were adopted to study the effects of N rate on rice yield, quality and N use efficiency. The differences between N requirement for obtaining the highest yield and for achieving the best economic benefit were compared. With the increase of N fertilizer rate, the yields of five super japonica rice cultivars increased firstly and then descended, achieving the highest yield at the N level of 300 kg x hm(-2) ranging from 10.33-10.60 kg x hm(-2). Yield increase mainly attributed to the large number of spikelet, for the total spikelet number of each rice cultivar reached the maximum value at the 300 kg x hm(-2) N level. With the increase of N application, the rates of brown rice, milled rice, head milled rice and the protein content of the five super japonica rice cultivars were all increased, and the rates of brown rice, milled rice, head milled rice and the protein con- tent were higher at 337.5 kg x hm(-2) N level than at 0 kg x hm(-2) N level by 3.3%-4.2%, 2.9%-6.0%, 4.4%-33.7% and 23.8%-44.3%, respectively. While the amylose content, gel consistency and taste value of the five rice cultivars were all decreased, and the amylose content, gel consistency and taste value were lower at 337.5 kg x hm(-2) N level than at 0 kg x hm(-2) N level by 12.4%-38.9%, 10.3%-28.5% and 20.3%-29.7%, respectively. The chalkiness increased firstly and then decreased while the change of chalky rate varied with the cultivars. With the increase of N application, the N use efficiency, agronomic N use efficiency and physiological N use efficiency decreased while the N uptake of grain increased significantly. If the cost of N fertilizer was taken into account, the N fertilizer amount to obtain the optimal economic benefits would be 275.68 kg x hm(-2) with the corresponding yield of 9.97 t x hm(-2). Therefore, in the existing super rice production, classified management of N fertilizer would be required to meet differentiated demands of high yield, good quality, high efficiency, low N fertilizer input and so on.