Rice OsLHT1 Functions in Leaf-to-Panicle Nitrogen Allocation for Grain Yield and Quality.

Proper allocation of nitrogen (N) from source leaves to grains is essential step for high crop grain yield and N use efficiency. In rice (Oryza sativa) grown in flooding paddy field, amino acids are the major N compounds for N distribution and re-allocation. We have recently identified that Lysine-Histidine-type Transporter 1 (OsLHT1) is the major transporter for root uptake and root-to-shoot allocation of amino acids in rice. In this study, we planted knockout mutant lines of OsLHT1 together wild-type (WT) in paddy field for evaluating OsLHT1 function in N redistribution and grain production. OsLHT1 is expressed in vascular bundles of leaves, rachis, and flowering organs. Oslht1 plants showed lower panicle length and seed setting rate, especially lower grain number per panicle and total grain weight. The concentrations of both total N and free amino acids in the flag leaf were similar at anthesis between Oslht1 lines and WT while significantly higher in the mutants than WT at maturation. The Oslht1 seeds contained higher proteins and most of the essential free amino acids, similar total starch but less amylose with lower paste viscosity than WT seeds. The mutant seeds showed lower germination rate than WT. Knockout of OsLHT1 decreased N uptake efficiency and physiological utilization efficiency (kg-grains/kg-N) by about 55% and 72%, respectively. Taken together, we conclude that OsLHT1 plays critical role in the translocation of amino acids from vegetative to reproductive organs for grain yield and quality of nutrition and functionality.

Oryza sativa Lysine-Histidine-type Transporter 1 functions in root uptake and root-to-shoot allocation of amino acids in rice.

In agricultural soils, amino acids can represent vital nitrogen (N) sources for crop growth and yield. However, the molecular mechanisms underlying amino acid uptake and allocation are poorly understood in crop plants. This study shows that rice (Oryza sativa L.) roots can acquire aspartate at soil concentration, and that japonica subspecies take up this acidic amino acid 1.5-fold more efficiently than indica subspecies. Genetic association analyses with 68 representative japonica or indica germplasms identified rice Lysine-Histidine-type Transporter 1 (OsLHT1) as a candidate gene associated with the aspartate uptake trait. When expressed in yeast, OsLHT1 supported cell growth on a broad spectrum of amino acids, and effectively transported aspartate, asparagine and glutamate. OsLHT1 is localized throughout the rice root, including root hairs, epidermis, cortex and stele, and to the leaf vasculature. Knockout of OsLHT1 in japonica resulted in reduced root uptake of amino acids. Furthermore, in 15 N-amino acid-fed mutants versus wild-type, a higher percentage of 15 N remained in roots instead of being allocated to the shoot. 15 N-ammonium uptake and subsequently the delivery of root-synthesized amino acids to Oslht1 shoots were also significantly decreased, which was accompanied by reduced shoot growth. These results together provide evidence that OsLHT1 functions in both root uptake and root to shoot allocation of a broad spectrum of amino acids in rice.

Optimal route of gold nanoclusters administration in mice targeting Parkinson's disease.

Aim: To explore the optimal route of gold nanoclusters (AuNCs) administration in mice targeting Parkinson's disease. Materials & methods: Assessing the pharmacokinetic and bioavailability of AuNCs in mice administrated following intravenous, intraperitoneal, gavage and intranasal injection. Investigating the biodistribution of AuNCs in mice by atomic absorption spectrometry and transmission electron microscope. Toxicity assessments of AuNCs were carried out both in cells and in mice. Results: Administration of AuNCs via intraperitoneal injection showed the greatest bioavailability and the longest residence in brain. AuNCs could penetrate blood-brain barrier and be excreted mainly through kidney. No obvious toxicity of AuNCs found in cells and in mice. Conclusion: The optimal route of AuNCs administration in mice targeting Parkinson's disease is intraperitoneal administration.

Olanzapine-induced endoplasmic reticulum stress and inflammation in the hypothalamus were inhibited by an ER stress inhibitor 4-phenylbutyrate.

Antipsychotics are the most important treatment for schizophrenia. However, antipsychotics, particularly olanzapine and clozapine, are associated with severe weight gain/obesity side-effects. Although numerous studies have been carried out to identify the exact mechanisms of antipsychotic-induced weight gain, it is still important to consider other pathways. Endoplasmic reticulum (ER) stress signaling and its associated inflammation pathway is one of the most important pathways involved in regulation of energy balance. In the present study, we examined the role of hypothalamic protein kinase R like endoplasmic reticulum kinase- eukaryotic initiation factor 2α (PERK-eIF2α) signaling and the inflammatory IkappaB kinase ß- nuclear factor kappa B (IKKß-NFκB) signaling pathway in olanzapine-induced weight gain in female rats. In this study, we found that olanzapine significantly activated PERK-eIF2α and IKKß-NFκB signaling in SH-SY5Y cells in a dose-dependent manner. Olanzapine treatment for 8 days in rats was associated with activated PERK-eIF2α signaling and IKKß-NFκB signaling in the hypothalamus, accompanied by increased food intake and weight gain. Co-treatment with an ER stress inhibitor, 4-phenylbutyrate (4-PBA), decreased olanzapine-induced food intake and weight gain in a dose- and time-dependent manner. Moreover, 4-PBA dose-dependently inhibited olanzapine-induced activated PERK-eIF2α and IKKß-NFκB signaling in the hypothalamus. These results suggested that hypothalamic ER stress may play an important role in antipsychotic-induced weight gain.

Strigolactones affect the translocation of nitrogen in rice.

Strigolactones (SLs) are involved in the nutrient-dependent control of plant root and shoot architecture. The total sufficient uptake of nitrogen (N), and also its appropriate distribution, is essential for the normal growth and development of plants; however, the effect of SLs on N translocation in plants remains unknown. Here, the SL-signaling mutant dwarf 3 (d3), the biosynthesis mutant dwarf 10 (d10), and wild-type (WT) rice (Oryza sativa ssp. Japonica cv. Nipponbare) were used to investigate the relationship between N nutrition and the regulatory role of SLs. Relative to WT, the d10 mutant had a higher N concentration in older leaves but a lower N concentration in younger leaves, while the d3 mutant showed a considerably lower N concentration, especially in its younger leaves under normal N levels. By contrast, both d3 and d10 mutants contained higher N in their leaves under N-deficient conditions. The 15N uptake and distribution analysis revealed that the significantly different N concentrations among the d3, d10, and WT plants only occurred in their leaves, not in their roots. Moreover, when provided with an external supply of GR24, the synthetic SLs altered the leaf N distribution of the d10 mutant but not those of the d3 mutant and WT. Together, these results suggested that the effect of SLs on plant growth and development may be linked to N translocation to different shoot tissues.