Novel Alkaloids from Marine Actinobacteria: Discovery and Characterization

The marine environment is an excellent resource for natural products with therapeutic potential. Its microbial inhabitants, often associated with other marine organisms, are specialized in the synthesis of bioactive secondary metabolites. Similar to their terrestrial counterparts, marine Actinobacteria are a prevalent source of these natural products. Here, we discuss 77 newly discovered alkaloids produced by such marine Actinobacteria between 2017 and mid-2021, as well as the strategies employed in their elucidation. While 12 different classes of alkaloids were unraveled, indoles, diketopiperazines, glutarimides, indolizidines, and pyrroles were most dominant. Discoveries were mainly based on experimental approaches where microbial extracts were analyzed in relation to novel compounds. Although such experimental procedures have proven useful in the past, the methodologies need adaptations to limit the chance of compound rediscovery. On the other hand, genome mining provides a different angle for natural product discovery. While the technology is still relatively young compared to experimental screening, significant improvement has been made in recent years. Together with synthetic biology tools, both genome mining and extract screening provide excellent opportunities for continued drug discovery from marine Actinobacteria.     

Pectin purified from pomelo (Citrus maxima) peel as a natural hatching agent for fish embryos

Pectin is a biodegradable polysaccharide, and it has been recently applied as a gene delivery, drug delivery, wound healing and tissue engineering agent. In this study, pectin was extracted from pomelo (Citrus maxima) peel and characterized. The extraction recovery of pectin form pomelo peel was 14.5%, and it had 72.56% degree of esterification, 1,245.56 equivalent weight, 7.82% methoxyl and 68.27% anhydrouronic acid contents. Use of pomelo pectin as a hatching enhancing agent for fish embryos and its effect on hatching enzyme 1 (ZHE1) was investigated. The pectin‐exposed zebrafish embryos (100 µg/ml) showed significantly (p < .05) higher hatching rate (96.6%) compared with untreated (control) embryos (66.6%) at 60 hpf. The mRNA expression of ZHE1 was also significantly (p < .05) elevated up to 55.6‐fold in pectin‐exposed embryos at 24 hpf. In situ hybridization results revealed remarkably strong expression of ZHE1 in pectin‐exposed embryos compared with the control group. In addition, considerably larger size of the hatching gland was observed in pectin‐exposed larvae than that of the unexposed larvae group. These results clearly indicate that pectin isolated from pomelo peel has an ability to enhance the hatching process of zebrafish embryos via upregulation of ZHE1.     

黄瓜根际促生菌的促生效应与防病作用

对黄瓜植物根际促生菌(PGPR)菌株的分离筛选、分类鉴定以及人们对其促生防病作用的应用和防病机制的研究现状进行了综述,以期为新型PGPR制剂的进一步研制、开发和应用提供参考.     

卡隆卡水电站钢岔管结构优化与设计

根据卡隆卡水电站的工程规模和特点,选用内加强月牙肋钢岔管,利用自行编制的计算机辅助设计程序进行岔管体彤的优化设计,并采用三维有限元法对所设计的岔管进行计算分析.计算结果表明,经过优化设计的钢岔管结构安全、合理,不仅可以满足运行要求,而且使最大管壁厚度减小为32 mm,与直径的比值为2.3%,分别小于规范规定的36 mm和t/d值为2.5%(Q390钢).可以满足钢材冷加工的要求,解决了高水头、小直径钢岔管加工工艺上的困难.     

我国南方大豆地方品种农艺和品质性状的遗传参数分析

由南方13省区的3769份夏大豆地方品种按省分层随机抽样而得的143份材料组成地方群体;由20份南方夏大豆推广品种及品系组成改良群体,在南京两年三重复试验表明,南方地方群体主要特点是晚熟(132.56天),秆较矮(58.05cm),中粒(14.34g/100粒),底荚高(18.47cm),分枝中等(3.86),产量低(1199.25kg/ha),蛋白质含量高(43.73％)、脂肪含量中等(20.19％)。该群体农艺和品质性状具有丰富的遗传变异,并由5％相对遗传进展特点将45个性状分为,GSI:极大(>40％);GSⅡ:大(40％—10％);GSⅢ:中等(10％—5％);GSⅣ:一定(<5％)等四类,其中GSⅠ、GSⅡ类多属产量、生育期、粒茎比、株高、百粒重等农艺性状,GSⅢ、GSⅣ类多属蛋白质含量及其氨基酸组分、脂肪含量等品质性状。     

SUSTAINABLE NUTRIENT MANAGEMENT PACKAGE FOR COST-EFFECTIVE BIOENERGY BIOMASS PRODUCTION

Commercial fertilizer (particularly nitrogen) costs account for a substantial portion of the total production costs of cellulosic biomass and can be a major obstacle to biofuel production. In a series of greenhouse studies, we evaluated the feasibility of co-applying Gibberellins (GA) and reduced nitrogen (N) rates to produce a bioenergy crop less expensively. In a preliminary study, we determined the minimum combined application rates of GA and N required for efficient biomass (sweet sorghum, Sorghum bicolor) production. Co-application of 75 kg ha^?1 (one-half of the recommended N rate for sorghum) and a modest GA rate of 3 g ha^?1 optimized dry matter yield (DMY) and N and phosphorus (P) uptake efficiencies, resulting in a reduction of N and P leaching. Organic nutrient sources such as manures and biosolids can be substituted for commercial N fertilizers (and incidentally supply P) to further reduce the cost of nutrient supply for biomass production. Based on the results of the preliminary study, we conducted a second greenhouse study using sweet sorghum as a test bioenergy crop. We co-applied organic sources of N (manure and biosolids) at 75 and 150 kg PAN ha^?1 (representing 50 and 100% N rate respectively) with 3 g GA ha^?1. In each batch of experiment, the crop was grown for 8 wk on Immokalee fine sand of minimal native fertility. After harvest, sufficient water was applied to soil in each pot to yield ～1.5 L (～0.75 pore volume) of leachate, and analyzed for total N and soluble reactive P (SRP). The reduced (50%) N application rate, together with GA, optimized biomass production. Application of GA at 3 g ha^?1, and the organic sources of N at 50% of the recommended N rate, decreased nutrient cost of producing the bioenergy biomass by ～$375 ha^?1 (>90% of total nutrient cost), and could reduce offsite N and P losses from vulnerable soils.     

基于倾向值匹配方法的土地督察制度的耕地保护效应研究

[目的]评估土地督察对耕地保护的效果以及解决样本选择带来的内生性问题,进一步完善土地督察制度提供理论支持。[方法]收集1999—2008年的省级面板数据,基于倾向值匹配分析估计土地督察的耕地保护效果。[结果](1)通过匹配变量的平衡性检验,最终采用了内核匹配方法。运用内核匹配法进行匹配估算,专项督察每年减少建设占用耕地面积8 037.489hm~2,例行督察每年减少建设占用耕地面积62 741.880hm~2。(2)专项督查地区的选择并非随机产生的,由此产生了样本选择偏误,即由于样本选择产生的内生性问题,采用倾向值匹配方法能够更为准确地估算专项督查的耕地保护效果。(3)例行督察对地区的选择相对专项督查而言,随机性更强,督察也更为全面,因此样本选择偏误也较小。以被督察地区面积比重表达政策变量方式估计得到的例行督查耕地保护效果要比倾向值匹配方法估计得到的结果更为可靠。[结论]例行督察的耕地保护效果较好。在土地政策评估中,需要考虑政策及其对象的相互关系的不同,以此考虑政策效果评估方法的选择。     

优质稻核心种质青六矮1号及其衍生品种的性状相关性研究

对青六矮1号及其衍生品种(品系)的相关分析表明: 产量与有效穗数呈极显著正相关, 与每穗总粒数和每穗实粒数呈显著负相关; 倒三叶长与倒二叶长呈极显著正相关, 与着粒密度呈显著负相关, 与粒长呈显著正相关, 与垩白率呈显著负相关, 与垩白度呈极显著负相关, 与胶稠度呈显著正相关, 与直链淀粉含量呈显著负相关. 主成分分析表     

浓缩风能型风力发电机的整体模型风洞实验（第Ⅲ报）

低速风洞内进行的实验结果表明：当风速为５．５０ｍ／ｓ时，浓缩风能型风力发电机模型的输出功率为１００Ｗ，是直径相等的普通型风力发电机（风力机和发电机的总机械效率为０．３３２时）的输出功率的３．８倍；其输出功率相当于目前我国草原上使用的小型风力发电机输出功率的６倍；并且该机组的起动风速比相同叶轮普通型风力发电机模型的起动风速低     

Behavior of Brick Samples in Aggressive Environments

The weathering of different brick samples ina range of aggressive environments has been studied.Brick samples were prepared using two clay types (fromGranada, Spain), different additives, and a range offiring temperatures (850–1100 °C). The brickscompositional and textural characteristics wereevaluated using XRD, SEM, hydric tests and mercuryintrusion porosimetry (MIP). The samples weresubjected to accelerate aging, including wet-dry,freeze-thaw and salt crystallization cycles. The decayof the bricks in polluted atmospheres was simulated ina static chamber containing sulfur dioxide (SO₂)at 25 °C and 50% relative humidity. Samplesfired at 1000 °C proved to be the most durable,with better hydric behavior (fast drying and slowwater absorption) and fewer micropores. However, theywere not suitable for salt-rich environments (badperformance in the salt decay test). Samples fired at850 °C turned out to be more resistant to saltdecay, but they showed a poor hydric behavior (slowdrying and rapid water absorption) and littleresistance to freeze-thaw and wet-dry cycles. Samplesfired at 1100 °C had good hydric behavior, theyperformed well in the salt decay test, but they didnot perform as well as the samples fired at1000 °C in most accelerated aging tests. Gypsumformed on all the brick samples submitted to SO₂atmosphere regardless exposure time (e.g. gypsumappears following just 24 h of exposure),composition, or firing temperature. Samples withdeposited particulate matter collected from vehicleexhausts (diesel, as well as leaded and non-leadedgasoline motor cars) resulted in the fastest gypsumdevelopment and greater abundance. On the other hand,the blank samples, and the samples withpollution-derived dust collected from historicalbuildings showed little gypsum development. Theimplications of these results in historicalbrick-building preservation in a range of aggressiveenvironments, and in polluted atmospheres inparticular, are discussed.