Approaches to Configuration Determinations of Flexible Marine Natural Products: Advances and Prospects

Flexible marine natural products (MNPs), such as eribulin and bryostatin, play an important role in the development of modern marine drugs. However, due to the multiple chiral centers and geometrical uncertainty of flexible systems, configuration determinations of flexible MNPs face great challenges, which, in turn, have led to obstacles in druggability research. To resolve this issue, the comprehensive use of multiple methods is necessary. Additionally, configuration assignment methods, such as X-ray single-crystal diffraction (crystalline derivatives, crystallization chaperones, and crystalline sponges), NMR-based methods (JBCA and Mosher’s method), circular dichroism-based methods (ECCD and ICD), quantum computational chemistry-based methods (NMR calculations, ECD calculations, and VCD calculations), and chemical transformation-based methods should be summarized. This paper reviews the basic principles, characteristics, and applicability of the methods mentioned above as well as application examples to broaden the research and applications of these methods and to provide a reference for the configuration determinations of flexible MNPs.     

列宁《论合作社》思想对中国农民合作社发展的启示

《论合作社》是列宁晚年阐述经济发展新思路的重要著作,科学阐明了列宁的合作经济理论,系统论证了合作社与社会主义的关系,明确指出了发展合作社的原则、方式与方法,对于新时代我国建立新型农业合作,大力发展合作社生产力,进而提高农民劳动积极性和市场竞争力具有重要意义。     

海鲜菇菌糠微生物发酵及其在肉羊瘤胃降解特性研究

【目的】探究不同微生物菌剂对海鲜菇菌糠发酵效果的影响,并研究其在肉羊瘤胃内降解特性。【方法】以海鲜菇菌糠为主要原料,分别添加0.1%植物乳杆菌、0.1%活菌多复合发酵菌剂、0.1%活菌多复合发酵菌剂＋3%糖蜜以及3%糖蜜,以不添加菌剂和糖蜜的处理为对照组。每处理3个重复,室温厌氧发酵45 d后,取样测定其营养成分（干物质（DM）、粗蛋白（CP）、中性洗涤纤维（NDF）和酸性洗涤纤维（ADF）含量）及发酵品质（pH及乳酸、乙酸、丙酸和丁酸含量）。取发酵效果最佳处理的发酵菌糠和菌糠原料进行瘤胃降解试验,测定发酵前后海鲜菇菌糠DM、CP、NDF和ADF不同发酵时间点（4,8,12,24,48及72 h）的瘤胃降解率,并计算降解参数及有效降解率。【结果】与对照组相比,各试验组CP含量均升高,NDF含量均降低,其中0.1%活菌多复合发酵菌剂＋3%糖蜜处理发酵效果最佳,其CP含量提高了9.69%（P＜0.05）,NDF、ADF和半纤维素含量分别下降了9.12%（P＜0.05）,2.66%和28.71%。各试验组pH较对照组均显著降低（P＜0.05）,乳酸含量均升高,其中0.1%活菌多复合发酵菌剂＋3%糖蜜处理组pH值最低,为3.29,乳酸含量最高（7.84%）,较对照组提高了33.11%（P＜0.05）。0.1%活菌多复合发酵菌剂＋3%糖蜜处理组菌糠DM、CP、NDF和ADF的72 h瘤胃降解率较发酵前分别提高了8.61%,8.58%,14.75%和8.93%（P＜0.05）,有效降解率较发酵前分别提高了7.66%,11.75%,20.74%和3.39%（P＞0.05）。【结论】在海鲜菇菌糠中添加0.1%活菌多复合发酵菌剂＋3%糖蜜能明显提高其营养价值、发酵品质及其在肉羊瘤胃中的降解率。     

1993年全国小麦秆锈菌种群动态分析

１９９３年我国小麦秆锈病发生较轻，从８个省１８个区县中的４７个品种上采集到的９５个标样中分离到菌株３３６个，鉴定出２１Ｃ３ＣＫＲ、２１Ｃ３ＣＫＨ、２１Ｃ３ＣＴＲ、２１Ｃ３ＣＴＨ、２１Ｃ３ＣＦＲ、２１Ｃ３ＣＦＨ、３４Ｃ１ＭＫＲ、３４Ｃ１ＭＫＨ和３４Ｃ２ＭＫＲ等９个致病类型；２１Ｃ３ＣＫＲ的出现频率为６５．２％，居于首位，２１Ｃ３ＣＤＨ为１４．５％，２１Ｃ３ＣＴＲ为１０．７％，２１Ｃ３ＣＦＲ为４．２％     

Investigation and integrated molecular diagnosis of root-knot nematodes in Panax notoginseng root in the field

Root-knot nematodes (RKNs, Meloidogyne spp.) are damaging pests that can infect thousands of plant species and cause enormous crop losses worldwide. Panax notoginseng is a common host of root-knot nematodes. In this study, we surveyed notoginseng gardens and determined the incidence of RKNs. Among the gardens surveyed, 71 % were infected with RKNs, and the RKN incidence index ranged from 8 % to 47 % in three randomly infected gardens. Meloidogyne hapla was identified as the pathogenic nematode based on 18S ribosomal RNA analysis by DNA barcoding. The results were qualitatively and quantitatively confirmed using a real-time PCR assay according to variations in the ITS1 and ITS2 regions. These results indicated that the combination of DNA barcoding and real-time PCR is a reliable and precise method for identifying parasitic nematodes from mixed-infected plant roots in the field. In addition, the abundance of ITS1 and ITS2 displayed a similar trend to the numbers of RKNs in the three gardens, which suggests that the results of real-time PCR can be used to determine the damage caused by M. hapla in the field. Our studies show that RKNs are common and can cause serious damage to notoginseng. We present an integrated method of detecting mixed nematode species in the field and confirm M. hapla as the target for parasitic nematode control in notoginseng gardens. Our results contribute to the improvement of RKN control in notoginseng and further promote the sustainable development of medicinal plants.     

完善的后续政策是巩固退耕还林成果的重要前提

1999年以来,长江上游、黄河上中游等地区开展的退耕还林的试点工作,是加强西部地区生态环境建设和保护的重要举措,也是贫困山区农民脱贫致富的有效途径.目前,第一批退耕还林工程现已进入成果巩固阶段,但是,原有的政策措施已不适应成果巩固阶段的要求.为把退耕还林工作扎实、稳妥、健康地向前推进,必须进一步完善退耕还林的政策措施.针对退耕还林工程中存在的问题,提出了巩固退耕还林成果的后续政策.     

天山北坡平原区水面蒸发的实验研究

本文以新疆地勘局昌吉地下水均衡试验场２０ｍ６３水面蒸发池水面蒸发量及常规气象观测资料为基础,应用灰色关联分析方法分析了各气象要素对水面蒸发量的影响程度,给出了Ｅ６０１蒸发四和Φ２０蒸发器水面蒸发折算系数,建立了计算水面蒸发量的经验公式。     

科尔沁沙地坨甸交错区土壤水分的空间变异规律

科尔沁沙地沙丘-草甸相间地区,地貌形态多样、土地利用类型众多,从而导致土壤水分空间分布的复杂性。通过对科尔沁沙地典型沙丘-草甸相间地区的调查取样与试验分析,运用统计学理论和方法,研究土壤水分的空间变异性及其空间分布规律。结果表明：水平方向上,土壤水分总体表现为草甸地大于沙丘地,过渡带介于两者之间。就草甸地而言,植物生长越好,其土壤水分越高,保水持水性能也越好;沙丘地则与之相反,植被最稀疏的流动沙丘,其土壤含水量大于半流动半固定沙丘与固定沙丘,且有良好的储水条件。垂向上,高覆盖草甸、低覆盖草甸和农田（草甸）土壤含水量在地表下0～40 cm波动最大,40～160 cm随深度增加而递增;流动沙丘、半流动沙丘和固定沙丘土壤含水量随深度增加呈微弱加大趋势。林地、撂荒地、农田（沙丘）变化程度居中。从空间分布看,研究区中东部土壤水分偏大,且向南北两侧区域递减。