Regulation of Nitrogen Metabolism,Photosynthetic Activity,and Yield Attributes of Spring Wheat by Nitrogen Fertilizer in the Semi-arid Loess Plateau Region

It is critical for spring wheat (Triticum aestivum L.) production in the semi-arid Loess Plateau to understand the impact of nitrogen (N) fertilizer on changes in N metabolism, photosynthetic parameters, and their relationship with grain yield and quality. The photosynthetic capacity of flag leaves, dry matter accumulation, and N metabolite enzyme activities from anthesis to maturity were studied on a long-term fertilization trial under different N rates [0 kg ha^?1(N1), 52.5 kg ha^?1 (N2), 105 kg ha^?1 (N3), 157.5 kg ha^?1 (N4), and 210 kg ha^?1 (N5)]. It was observed that N3 produced optimum total dry matter (5407 kg ha^?1), 1000 grain weight (39.7 g), grain yield (2.64 t ha^?1), and protein content (13.97%). Our results showed that N fertilization significantly increased photosynthetic parameters and N metabolite enzymes at all growth stages. Nitrogen harvest index, partial productivity factor, agronomic recovery efficiency, and nitrogen agronomic efficiency were decreased with increased N. Higher N rates (N3–N5) maintained higher photosynthetic capacity and dry matter accumulation and lower intercellular CO₂ content. The N supply influenced NUE by improving photosynthetic properties. The N3 produced highest chlorophyll content, photosynthetic rate, stomatal conductance and transpiration rate, grain yield, grain protein, dry matter, grains weight, and N metabolite enzyme activities compared to the other rates (N1, N2, N4, and N5). Therefore, increasing N rates beyond the optimum quantity only promotes vegetative development and results in lower yields.

     

A simple process for the isolation of epithelial cells from bacteria-contaminated samples using anchoring molecules

A simple and efficient tool to isolate epithelial cells from bacteria-contaminated samples has been developed using two different microparticles functionalized with chemical molecules. The epithelial cells could be captured simply by biocompatible anchors for membranes (BAM), consisting of poly(ethylene glycol) functionalized with oleyl-chain-conjugated NHS (N-hydroxysuccinimide) on glass microparticles, whereas bacteria were adsorbed on 3-aminopropyltrimethoxysilane (ATPS)-functionalized magnetic microparticles. In the case of samples highly contaminated with bacteria, epithelial cells were not isolated successfully by both of the single BAM- and antibody-functionalized microparticles. Therefore, serial isolation steps of these two different chemical functionalized microparticles were introduced. The concentration of bacteria was decreased dramatically by using APTS-functionalized magnetic particles prior to the isolation of epithelial cells by BAM microparticles. With these serial processes, successful isolation of epithelial cells was achieved from bacteria-contaminated epithelial samples. The applicability of this method was verified with bacteria-contaminated intestinal samples biopsied from a BALB/C mouse for primary cell cultivation.     

Phosphorus alleviation of nitrogen‐suppressed methane sink in global grasslands

Grassland ecosystems account for more than 10% of the global CH₄ sink in soils. A 4‐year field experiment found that addition of P alone did not affect CH₄ uptake and experimental addition of N alone significantly suppressed CH₄ uptake, whereas concurrent N and P additions suppressed CH₄ uptake to a lesser degree. A meta‐analysis including 382 data points in global grasslands corroborated these findings. Global extrapolation with an empirical modelling approach estimated that contemporary N addition suppresses CH₄ sink in global grassland by 11.4% and concurrent N and P deposition alleviates this suppression to 5.8%. The P alleviation of N‐suppressed CH₄ sink is primarily attributed to substrate competition, defined as the competition between ammonium and CH₄ for the methane mono‐oxygenase enzyme. The N and P impacts on CH₄ uptake indicate that projected increases in N and P depositions might substantially affect CH₄ uptake and alter the global CH₄ cycle.     

Bone morphogenetic protein-7 (BMP-7) mediates ischemic preconditioning-induced ischemic tolerance via attenuating apoptosis in rat brain

A mild cerebral ischemic insult, also known as ischemic preconditioning (IPC), confers transient tolerance to a subsequent ischemic challenge in the brain. This study was conducted to investigate whether bone morphogenetic protein-7 (BMP-7) is involved in neuroprotection elicited by IPC in a rat model of ischemia. Ischemic tolerance was induced in rats by IPC (15 min middle cerebral artery occlusion, MCAO) at 48 h before lethal ischemia (2 h MCAO). The present data showed that IPC increased BMP-7 mRNA and protein expression after 24 h reperfusion following ischemia in the brain. In rats of ischemia, IPC-induced reduction of cerebral infarct volume and improvement of neuronal morphology were attenuated when BMP-7 was inhibited either by antagonist noggin or short interfering RNA (siRNA) pre-treatment. Besides, cerebral IPC-induced up-regulation of B-cell lymphoma 2 (Bcl-2) and down-regulation of cleaved caspase-3 at 24 h after ischemia/reperfusion (I/R) injury were reversed via inhibition of BMP-7. These findings indicate that BMP-7 mediates IPC-induced tolerance to cerebral I/R, probably through inhibition of apoptosis.     

Reducing AsA Leads to Leaf Lesion and Defence Response in Knock-Down of the AsA Biosynthetic Enzyme GDP-D-Mannose Pyrophosphorylase Gene in Tomato Plant

As a vital antioxidant, L-ascorbic acid (AsA) affects diverse biological processes in higher plants. Lack of AsA in cell impairs plant development. In the present study, we manipulated a gene of GDP-mannose pyrophosphorylase which catalyzes the conversion of D-mannose-1-P to GDP-D-mannose in AsA biosynthetic pathway and found out the phenotype alteration of tomato. In the tomato genome, there are four members of GMP gene family and they constitutively expressed in various tissues in distinct expression patterns. As expected, over-expression of SlGMP3 increased total AsA contents and enhanced the tolerance to oxidative stress in tomato. On the contrary, knock-down of SlGMP3 significantly decreased AsA contents below the threshold level and altered the phenotype of tomato plants with lesions and further senescence. Further analysis indicated the causes for this symptom could result from failing to instantly deplete the reactive oxygen species (ROS) as decline of free radical scavenging activity. More ROS accumulated in the leaves and then triggered expressions of defence-related genes and mimic symptom occurred on the leaves similar to hypersensitive responses against pathogens. Consequently, the photosynthesis of leaves was dramatically fallen. These results suggested the vital roles of AsA as an antioxidant in leaf function and defence response of tomato.