牛源无乳链球菌耐药性与毒力基因的表达量差异分析

【目的】 研究无乳链球菌对抗菌药物的耐药性,分析无乳链球菌毒力基因与耐药基因的携带情况。【方法】 分别采用微量肉汤稀释法和普通PCR的方法,检测牛源无乳链球菌对16种抗菌药物的耐药性和相关耐药基因及毒力基因,并且采用荧光定量PCR技术对不同菌株的8种毒力基因的表达量差异进行分析。【结果】 （1）无乳链球菌对11种药物的敏感性达到了65%以上,其中敏感性最高的是氟苯尼考（92.4.%）和头孢噻呋（88.4%）,对氨苄西林、红霉素、克林霉素的耐药率均达到了50%以上,对磺胺异恶唑的耐药率也达到了45%以上。（2）无乳链球菌耐药基因gyrA、sul1、ermB、ermC的检出率分别为100%、 86.67%、 93.3%、 33.3%,而ermA、sul2、sul3及parC 4种耐药基因未检出。（3）无乳链球菌毒力基因pavA、cfb、fbsA、bibA、cspA、sip、iagA、hylB的检出率为100%,rib检出率为13.3%,bca的检出率为53.3%,cyl E检出率为73.3%;未检测到bac、lmb、scp B这三种毒力基因。（4）不同菌株之间毒力基因的表达量有显著性差异（P<0.05）。【结论】 无乳链球菌对红霉素和克林霉素的耐药率较高,无乳链球菌毒力因子是宿主感染疾病的重要因素。     

油茶根系与内生细菌枯草芽孢杆菌互作早期的转录组分析

【目的】研究油茶-内生细菌互作早期的油茶根系转录组变化规律,为阐明油茶与内生细菌互作的分子机制提供依据。【方法】构建内生细菌枯草芽孢杆菌1-L-29gfp^r与油茶根系互作体系,以不同时间（0、6、12、24 h）的互作体系为研究材料,利用RNA-Seq技术对油茶根部进行转录组测序及分析。【结果】1)转录组测序共产生52 958 922条序列,约46.1 Gb,差异表达基因10 314条（FDR<0.05且|log₂FC|>1）。随着互作时间的延长差异表达基因数量呈高-低-高的趋势,接种6 h后差异表达基因数量为6 306个,其中显著上调3 434个,显著下调2 572个;接种12 h后显著上调903个,显著下调526个;接种24 h后显著上调1 195个,显著下调1 384个。2)GO富集分析表明：接种6 h油茶的生物学过程、分子功能方面变化最为明显,生物学过程中磷酸代谢、含磷化合物代谢、响应激素途径、茉莉酸代谢、响应细菌途径等;分子功能中萜烯合酶活性、双加氧酶活性等;细胞组分中膜固有成分等得到富集。3)KEGG通路分析中差异表达...     

The long-term effects of thinning and mixing on species and structural diversity of Chinese fir plantations

New Forests - Plantations are playing an increasingly important role in providing forest products and improving the ecological environment, but they also face many challenges, such as low...     

我国森林生态食品研究现状与发展策略

森林生态食品是近年来提出的新型森林生态标志产品,是继农产品"三品一标"与森林食品之后,融合了天然、绿色、安全、营养、健康等生态元素的新型食品标准.本文对森林生态食品的出现、发展及认定进行了综述,并提出了相应的发展策略.     

Interference competition and predation between invasive and native herbivores in maize

Interspecific interactions (e.g., competition, predation) are core determinants of insect population evolution, geographical distribution, trophic dynamics and ecosystem functioning. Following its recent invasion of eastern Asia, the fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae) co-inhabits maize fields with native lepidopteran herbivores, such as the common cutworm, Spodoptera litura. Here, drawing upon laboratory and field studies, we demonstrate how late-instar S. frugiperda larvae directly prey upon S. litura immature stages and competitively displace them from the maize whorl. Individual maize plants did not mediate the above interactions, with herbivore-damaged leaves not affecting the development rate of either species. In the field, ecological niches of S. frugiperda and S. litura overlapped, with species-specific occupancy rates of whorl-stage leaves (vegetative phase) and ears or tassels (reproductive phase) exceeding 70% and 90%, respectively. Field cage trials showed that S. frugiperda larvae either preyed upon or repelled S. litura larvae from maize plants, routinely resulting in more than 90% mortality of the latter. Field visits and cage studies in Yunnan (SW China) also revealed how—within an approx. 1-year time period—S. frugiperda has become a dominant species in local maize fields and co-infestation of both herbivores on the same plant is rare. Overall, our work shows how the invasive S. frugiperda exhibits a clear competitive advantage over native lepidopterans and could replace certain species within local agroecosystems. This study not only unveils the mechanistic causes of rapid ecological shifts within S. frugiperda-invaded cropping systems, but may also guide subsequent monitoring and management interventions.

     

实践教学资源库的应用现状及需求调查与分析

指出了在当前“互联网+”的时代背景下,信息化技术越来越多地应用到高等职业教育中,因此,建设适应时代发展的实践教学数字化资源库显得尤为重要。对实践教学数字化资源的认知情况、现有实践教学数字化资源的使用情况、化学类课程实践教学资源库的需求进行了调查分析,明确了以学生需求为导向进行实践教学数字化资源库建设的思路,通过建立专业的实践教学资源库建设团队,强化日常监管,保障资源库的长效运行。     

陕北榆林毛乌素沙地新开垦耕地空间分布特征——以靖边县为例

毛乌素沙地的开垦一方面增加了耕地资源保证了粮食安全,另一方面也造成了生态环境破坏、环境承载能力下降、资源分布不合理等现象,对新开垦耕地空间分布进行分析研究对于耕地空间分布优化和可持续利用具有重要意义.利用2010—2020年遥感影像获取陕北榆林毛乌素沙地新开垦耕地数据,并结合自然划分的地理空间地类数据等,分析新开垦耕地地理空间分布、影响因素及空间优化分布.研究表明,从地理空间来看,靖边县新开垦耕地空间分布特征及模式区域差异显著,北部地区新增耕地密度大,空间分布均匀;南部地区新增耕地密度小,空间分布较为集中;新开垦耕地分布受到政策、自然和社会三重因素影响.空间规划上要以北部毛乌素沙地重点开发,南部山区限制开发,引导农民合理有序进行土地开垦;要加强土地整治工程及高标准农田建设,对已开垦耕地运用工程建设措施,提高耕地集约节约化发展,达到改善农业生产、农民生活和生态环境的目的.     

金露梅黄酮提取工艺的响应面优化及其抗氧化和降血糖活性分析

【目的】优化金露梅中黄酮的超声提取工艺条件,检测黄酮化合物的种类及含量,并分析其抗氧化和降血糖活性,为金露梅的综合利用提供技术支持。【方法】以总黄酮提取率为指标,采用单因素和响应面分析法对超声提取金露梅黄酮的主要工艺参数进行优化分析,利用多重层析柱对黄酮化合物进行分离纯化,并比较各组分的抗氧化和降血糖活性。【结果】 4个因素对金露梅总黄酮提取率影响的显著性顺序为液料比>超声时间>乙醇体积分数>超声功率,建立的回归方程为Y=37.84+14.48A+14.93B+3.02C+9.38D-0.03AB-0.66AC-0.01AD-0.01BD-0.01CD-14.71A2-11.25B2-16.96C2-12.89D2（Y表示总黄酮提取率,A、B、C、D分别表示液料比、乙醇体积分数、超声功率和超声时间）;超声提取金露梅黄酮的最佳工艺条件为:液料比39.78:1 （mL/g）、乙醇体积分数65.47%、超声功率390.98 W、超声时间49.55 min,在此条件下金露梅总黄酮提取率为47.59 mg/g。金露梅黄酮化合物中发现含有8种化合物,其中含量最高的为槲皮素-7-O-β-D-葡萄糖醛酸（10.90 mg/g）。柚皮素对1,1-二苯基-2-三硝基苯肼（DPPH）自由基清除率最低,仅为5.0%,其余7种化合物对DPPH自由基的清除率均达50.0%以上,表现出良好的抗氧化活性。金露梅黄酮化合物对葡萄糖消耗率均高于二甲基亚砜（DMSO）,其中（+）-儿茶素、槲皮素-3-O-β-D-葡萄糖醛酸和3-阿拉伯葡萄糖基槲皮素对葡萄糖的消耗率达19.5%以上,表现出良好的降血糖活性。【结论】经响应面优化的金露梅黄酮超声提取工艺切实可行,建立的回归方程具有较高的准确性;多重层析柱法可实现金露梅中黄酮化合物的分离纯化,各组分除柚皮素外,均具有明显的抗氧化活性,且各组分化合物均有一定的降血糖活性。金露梅可作为一种天然抗氧化剂和降血糖剂来源在食品、医药等方面进行开发利用。     

Characterization and fine mapping of a semi-rolled leaf mutant srl3 in rice

Moderate leaf rolling can maintain leaf erectness, improve light transmittance in the population, and improve light energy utilization, thereby increasing rice yield. This study used ethyl methanesulfonate (EMS) to treat Yunjing 17 (YJ17) and obtained a semi-rolled leaf mutant that was named semi-rolledleaf3 (srl3). We found that the rolled-leaf phenotype was due to the aberrant development of bulliform cells and the loss of sclerenchymatous cells. In addition, the shoot and root length of srl3 seedlings differed from the wild type. The srl3 mutant had significantly lower plant height and seed-setting rate but notably greater tiller number, panicle length, and primary branch number per panicle than the wild type. Genetic analysis showed that a single recessive nuclear gene defined the srl3 mutant, and it was precisely located in a 144-kb region between two insertion-deletion (InDel) markers, M8 and M19, on chromosome 2. In this region, no leaf-rolling-related genes have been reported previously. Thus, the study indicated that SRL3 is a novel leaf-rolling-related gene, and the results laid the foundation for the cloning and functional analysis of the SRL3 gene.