黄土高原半湿润区苜蓿草地土壤干层形成及水分恢复

研究了黄土高原地区不同生长年限苜蓿草地0～1000 cm土层土壤水分消耗规律.结果表明,荒地与苜蓿草地土壤干层出现的区域及发生的程度不同:荒地在80～100 cm土层深度,出现轻度干层;生长年限低于8a(含8a)的苜蓿草地,在250～350 cm土层出现轻度干层,生长年限超过8a,出现中度干层,干层范围延至500 cm土层以下.苜蓿生长超过18a,0～200 cm上层土壤水分开始恢复,年均恢复1.49%;但在200～1000 cm土壤深层,18、26年生苜蓿草地土壤含水量仅为10.20%,深层土壤通体干化,水分难以恢复.     

Neuroimmune interactions in guinea pig stomach and small intestine

Enteric neuroimmune interactions in gastrointestinal hypersensitivity responses involve antigen detection by mast cells, mast cell degranulation, release of chemical mediators, and modulatory actions of the mediators on the enteric nervous system (ENS). Electrophysiological methods were used to investigate electrical and synaptic behavior of neurons in the stomach and small intestine during exposure to beta-lactoglobulin in guinea pigs sensitized to cow's milk. Application of beta-lactoglobulin to sensitized preparations depolarized the membrane potential and increased neuronal excitability in small intestinal neurons but not in gastric neurons. Effects on membrane potential and excitability in the small intestine were suppressed by the mast cell stabilizing drug ketotifen, the histamine H(2) receptor antagonist cimetidine, the cyclooxygenase inhibitor piroxicam, and the 5-lipoxygenase inhibitor caffeic acid. Unlike small intestinal ganglion cells, gastric myenteric neurons did not respond to histamine applied exogenously. Antigenic exposure suppressed noradrenergic inhibitory neurotransmission in the small intestinal submucosal plexus. The histamine H(3) receptor antagonist thioperamide and piroxicam, but not caffeic acid, prevented the allergic suppression of noradrenergic inhibitory neurotransmission. Antigenic stimulation of neuronal excitability and suppression of synaptic transmission occurred only in milk-sensitized animals. Results suggest that signaling between mast cells and the ENS underlies intestinal, but not gastric, anaphylactic responses associated with food allergies. Histamine, prostaglandins, and leukotrienes are paracrine signals in the communication pathway from mast cells to the small intestinal ENS.     

Identification of favorable SNP alleles and candidate genes responsible for inflorescence-related traits via GWAS in chrysanthemum

Key message

81 SNPs were identified for three inflorescence-related traits, in which 15 were highly favorable. Two dCAPS markers were developed for future MAS breeding, and six candidate genes were predicted.

Abstract

Chrysanthemum is a leading ornamental species worldwide and demonstrates a wealth of morphological variation. Knowledge about the genetic basis of its phenotypic variation for key horticultural traits can contribute to its effective management and genetic improvement. In this study, we conducted a genome-wide association study (GWAS) based on two years of phenotype data and a set of 92,617 single nucleotide polymorphisms (SNPs) using a panel of 107 diverse cut chrysanthemums to dissect the genetic control of three inflorescence-related traits. A total of 81 SNPs were significantly associated with the three inflorescence-related traits (capitulum diameter, number of ray florets and flowering time) in at least one environment, with an individual allele explaining 22.72–38.67% of the phenotypic variation. Fifteen highly favorable alleles were identified for the three target traits by computing the phenotypic effect values for the stable associations detected in 2 year-long trials at each locus. Dosage pyramiding effects of the highly favorable SNP alleles and significant linear correlations between highly favorable allele numbers and corresponding phenotypic performance were observed. Two highly favorable SNP alleles correlating to flowering time and capitulum diameter were converted to derived cleaved amplified polymorphic sequence (dCAPS) markers to facilitate future breeding. Finally, six putative candidate genes were identified that contribute to flowering time and capitulum diameter. These results serve as a foundation for analyzing the genetic mechanisms underlying important horticultural traits and provide valuable insights into molecular marker-assisted selection (MAS) in chrysanthemum breeding programs.

     

Inhibitory neuromuscular transmission mediated by the P2Y1 purinergic receptor in guinea pig small intestine

ATP is a putative inhibitory neurotransmitter responsible for inhibitory junction potentials (IJPs) at neuromuscular junctions (IJPs) in the intestine. This study tested the hypothesis that the purinergic P2Y(1) receptor subtype mediates the IJPs. IJPs were evoked by focal electrical stimulation in the myenteric plexus and recorded with "sharp" intracellular microelectrodes in the circular muscle coat. Stimulation evoked three categories of IJPs: 1) purely purinergic IJPs, 2) partially purinergic IJPs, and 3) nonpurinergic IJPs. Purely purinergic IJPs were suppressed by the selective P2Y(1) purinergic receptor antagonist MRS2179. Purely purinergic IJPs comprised 26% of the IJPs. Partially purinergic IJPs (72% of the IJPs) consisted of a component that was abolished by MRS2179 and a second unaffected component. The MRS2179-insensitive component was suppressed or abolished by inhibition of formation of nitric oxide by N(omega)-nitro-l-arginine methyl ester (l-NAME) in some, but not all, IJPs. An unidentified neurotransmitter, different from nitric oxide, mediated the second component in these cases. Nonpurinergic IJPs were a small third category (4%) of IJPs that were abolished by l-NAME and unaffected by MRS2179. Exogenous application of ATP evoked IJP-like hyperpolarizing responses, which were blocked by MRS2179. Application of apamin, which suppresses opening of small-conductance Ca(2+)-operated K(+) channels in the muscle, decreased the amplitude of the purinergic IJPs and the amplitude of IJP-like responses to ATP. The results support ATP as a neurotransmitter for IJPs in the intestine and are consistent with the hypothesis that the P2Y(1) purinergic receptor subtype mediates the action of ATP.     

Structure-aided optimization of 3-O-β-chacotriosyl ursolic acid as novel H5N1 entry inhibitors with high selective index

Currently, entry inhibitors contribute immensely in developing a new generation of anti-influenza virus drugs. Our earlier studies have identified that 3-O-β-chacotriosyl ursolic acid (1) could inhibit H5N1 pseudovirus by targeting hemagglutinin (HA). In the present study, a series of C-28 modified pentacyclic triterpene saponins via conjugation with a series of amide derivatives were synthesized and their antiviral activities against influenza A/Duck/Guangdong/99 virus (H5N1) in MDCK cells were evaluated. The SARs analysis of these compounds revealed that introduction of certain amide structures at the 17-COOH of ursolic acid could significantly enhance both their antiviral activity and selective index. This study indicated that the attachment of the methoxy group or Cl atom to the phenyl ring at the ortho- or para-position was crucial to improve inhibitory activity. Mechanism studies demonstrated that these title triterpenoids could bind tightly to the viral envelope HA to block the attachment of viruses to host cells, which was consistent with docking studies.     

Multilocus Typing of Enterocytozoon bieneusi in Pig Reveals the High Prevalence,Zoonotic Potential,Host Adaptation and Geographical Segregation in China

Enterocytozoon bieneusi is one of the most frequently diagnosed Microsporidia of humans and most animals. However, there is no information on E. bieneusi infection of pigs in Tibet and Henan, China. In this study, 1,190 fecal samples were collected from pigs in Tibet and Henan and screened for the presence of E. bieneusi. The overall prevalence of E. bieneusi infection was 54.2% (645/1,190), with differences in prevalence observed among geographical areas, ages, and pig breeds. Moreover, 10 E. bieneusi genotypes were identified based on internal transcribed spacer region genotyping, including eight known genotypes (EbpC, EbpA, CHG19, CHC5, Henan‐III, I, D, and H) and two novel genotypes (XZP‐I and XZP‐II). Multilocus sequence typing revealed 18, 7, 17, and 13 genotypes at minisatellite/microsatellite loci MS1, MS3, MS4, and MS7, respectively. Strong linkage disequilibrium (LD) and few numbers of recombination events, suggest a clonal structure of the E. bieneusi population examined in this study. The low pairwise genetic distance (F_ST) and gene flow (Nm) values indicated limited gene flow in the E. bieneusi population from different hosts, with phylogenetic, structure, and median‐joining network analyses all indicating the existence of host and geographical isolation. The identification of isolates belonging to nine human‐pathogenic genotypes indicates that pigs play an important role in the dissemination of E. bieneusi, improving our present understanding of E. bieneusi epidemiology in the studied region.     

Metal-N-saccharide chemistry: synthesis and structure determination of two Cu(II) complexes containing glycosylamines

Two new complexes [Cu(N,N',N"-(D-Glc)3-tren)Cl]Cl (1) and [Cu(N,N',N"-(maltose)-tren)]Cl2.H2O (2), have been synthesized and characterized by elementary analysis, and the IR and UV spectra suggest that complex 1 and complex 2 are arranged in trigonal bipyramidal configuration and square-pyramidal configuration, respectively. The crystal structure of complex 1 has been determined by X-ray diffraction as: a = 9.3476(8), b = 17.4236(13), c = 9.7836(8) angstroms, beta = 91.197 degrees, and V = 1593.1(2) Angstroms3, Z = 2, and R = 0.0325, which shows that three secondary amine groups (N-1, N-2, N-3) of the glycosylamine ligand forms the equatorial plane, and the tertiary amine (N-4) and one Cl- are located at the apical positions.     

褐稻虱生物型的监测和控制对策

广西等11个省、市、自治区的褐稻虱Nilaparvata lugens(Stal)生物型监测表明：我国目前除成都的褐稻虱属生物型1外,其他均以生物型2为优势种群。还发现云南思茅和广 西南宁的褐稻虱有部分个体可致害含抗性基因bph2的ASDT和IR36。并鉴定选出一些抗生物型2的品种可供目前推广使用。尚发现广西药用野稻绝大多数材料、普通野稻部分材料以及国际水稻抗褐稻虱圃中Ptb33及其衍生品种(系)具有广谱抗性。若用以培育具广谱抗性的新品种,则是控制褐稻虱新生物型产生和暴发为害的一个重要对策。     

Biological synthesis of Au nanoparticles using liquefied mash of cassava starch and their functionalization for enhanced hydrolysis of xylan by recombinant xylanase

Au nanoparticles (AuNPs) have shown the potential for a variety of applications due to their unique physical and chemical properties. In this study, a facile and affordable method for the synthesis of AuNPs via the liquefied mash of cassava starch has been described and the functionalized AuNPs by l-cysteine improved activity of recombinant xylanase was demonstrated. UV–Vis absorption spectroscopy, transmission electron microscopy, and zeta potential measurements were performed to characterize the AuNPs and monitor their synthesis. The presence of Au was confirmed by energy-dispersive X-ray spectroscopy (EDX) and the X-ray diffraction patterns showed that Au nanocrystals were face-centered cubic. The C=O stretching vibration in the Fourier transform infrared spectrum of AuNPs suggested that the hemiacetal C–OH of sugar molecules performed the reduction of Au³⁺ to Au⁰. The presence of C and O in the EDX spectrum and the negative zeta potential of AuNPs suggested that the biomolecules present in liquefied cassava mash were responsible for the stabilization of AuNPs. The surface of AuNPs was easily functionalized by l-cysteine, which improved the stability of AuNPs. Moreover, cysteine-functionalized AuNPs could significantly improve recombinant xylanase efficiency and stability.     

东海赤潮高发区沉积物中叶绿素的分析

研究分析了2002年8～9月“赤潮973”航次所采集的沉积物中叶绿素a及其降解产物脱镁叶绿酸含量与分布．结果表明。叶绿素a和脱镁叶绿酸是同源的;随深度增加叶绿素a和脱镁叶绿酸的含量呈递减趋势,到一定深度后含量不再变化。个别站位叶绿素a和脱镁叶绿酸的垂直分布出现了许多小突跃,可能是由生物扰动引起;表层沉积物(0～0．5cm)中的叶绿素a和脱镁叶绿酸的变化幅度分别为0．14～1．17和0．83～5．58μg·g-1。平均值分别为0．54和2．45μg·g-1;并初步探讨水深(光强)、盐度、温度、含水量对叶绿素水平分布的影响;脱镁叶绿酸作为叶绿素的主要降解产物,到一定深度后,成为叶绿素的主要存在形式,约占80％～90％;由于水温的不同,夏季沉积物中的叶绿素a和脱镁叶绿酸含量是春季的3倍之多;比较了上层水柱中的叶绿素和沉积物中的叶绿素的相对含量,平均而言,沉积物中叶绿素占上层水柱中叶绿素的31％．