粪便分离大肠埃希菌CRISPR系统在耐药及毒力中的作用

目的 探索粪便分离大肠埃希菌成簇规律间隔短回文重复序列(clustered regularly interspaced short palindromic repeats,CRISPR)在耐药及毒力中的作用。 方法 收集某院2018年8-12月分离自慢性腹泻患者及健康体检者粪便样本的大肠埃希菌。采用纸片扩散法检测其药物敏感性,PCR法检测并比较分析腹泻患者及健康体检者粪便样本分离大肠埃希菌的系统发育群、耐药基因及CRISPR系统。 结果 共收集到142株大肠埃希菌,源于63例慢性腹泻患者(疾病组)和79例健康体检者(健康组)。药敏结果显示,氨苄西林耐药率为48.0%,其余抗菌药物敏感率为73.1%～100.0%。63株源于慢性腹泻患者粪便样本分离大肠埃希菌中CRISPR系统的检出率显著低于79株源于健康体检者(3.2% vs 46.8%,χ2=33.538,P2=8.656,P=0.003)。 结论 粪便分离大肠埃希菌对常用抗菌药物仍保持较高敏感性。CRISPR系统可能在粪便分离大肠埃希菌毒力及耐药基因的传播方面发挥重要作用。     

基于生态红线划定的祁连山生态保护性开发研究

运用祁连山地区的自然环境数据和社会经济数据,基于GIS平台、加权求和多指标运算模型,选取了30个指标,从生态弹性力、生态敏感性和社会经济影响力3个方面,构建了生态红线评价指标体系,对祁连山生态保护性开发进行研究分析。结果表明:生态红、黄、绿线区,分别占研究区面积的32%、40%、28%。生态红线区主要分布于祁连山的西南段、托来山以南、青海湖区及区内所有冰川分布地区,应实行最严格的管控;生态黄线区是祁连山分布面积最广的区域,主要集中在祁连山中、西段,湟水谷地的中游及乌鞘岭南部,应以修复生态环境和提供部分农产品为主;生态绿线区主要分布在疏勒南山以东地区,应保护优先,以提供生态产品为主,分区开展各具民族特色的生态旅游。     

禾谷镰孢霉nit突变体的诱导及其生物学特性

将3个抗多菌灵和2个野生敏感型禾谷镰孢霉(Fusarium graminearum)菌株分别在含氯酸盐的MMC培养基上培养,共得到22个不能利用硝酸盐的营养缺陷突变体(Nitrate nonutilizing mutant, 简称nit突变体)。比较了各nit突变体与其亲本菌株之间在菌落生长速率、培养性状、产分生孢子能力、产子囊壳能力以及对多菌灵的敏感性等生物学特性方面的变化。结果表明,nit突变体均抗氯酸盐,在PSA平板上的生长速率没有改变,有性生殖能力没有下降,在Joffs 培养液和5%绿豆汤培养液中仍能产孢,但产孢量与亲本菌株有差异。此外,禾谷镰孢霉对氯酸盐和多菌灵之间没有交互抗药性。因此,可用nit作为遗传标记,研究禾谷镰孢霉有关性状的遗传学。     

Effects of biochar addition on dynamics of soil respiration and temperature sensitivity in a Phyllostachys edulis forest

Aims Recent studies have shown that artificial addition of biochar is an effective way to mitigate atmospheric carbon dioxide concentrations. However, it is still unclear how biochar addition influences soil respiration in Phyllostachys edulis forests of subtropical China. Our objectives were to examine the effects of biochar addition on the dynamics of soil respiration, soil temperature, soil moisture, and the cumulative soil carbon emission, and to determine the relationships of soil respiration with soil temperature and moisture.Methods We conducted a two-year biochar addition experiment in a subtropical P. edulis forest from 2014.05 to 2016.04. The study site is located in the Miaoshanwu Nature Reserve in Fuyang district of Hangzhou, Zhejiang Province, in southern China. The biochar addition treatments included: control (CK, no biochar addition), low rate of biochar addition (LB, 5 t·hm^-2), medium rate of biochar addition (MB, 10 t·hm^-2), and high rate of biochar addition (HB, 20 t·hm^-2). Soil respiration was measured by using a LI-8100 soil CO₂ efflux system.Important findings Soil respiration was significantly reduced by biochar addition, and exhibited an apparent seasonal pattern, with the maximum occurring in June or July (except LB in one of the replicated stand) and the minimum in January or February. There were significant differences in soil respiration between the CK and the treatments. Annual mean soil respiration rate in the CK, LB, MB and HB were 3.32, 2.66, 3.04 and 3.24 μmol·m^-2·s^-1, respectively. Compared with CK, soil respiration rate was 2.33%-54.72% lower in the LB, 1.28%-44.21% lower in the MB, and 0.09%-39.22% lower in the HB. The soil moisture content was increased by 0.97%-75.58% in LB, 0.87%-48.18% in MB, and 0.68%-74.73% in HB, respectively, compared with CK. Soil respiration exhibited a significant exponential relationship with soil temperature and a significant linear relationship with combination of soil temperature and moisture at the depth of 5 cm; no significant relationship was found between soil respiration and soil moisture alone. The temperature sensitivity (Q₁₀) value was reduced in LB and HB. Annual accumulative soil carbon emission in the LB, MB and HB was reduced by 7.98%-35.09%, 1.48%-20.63%, and -4.71%-7.68%, respectively. Biochar addition significantly reduced soil carbon emission and soil temperature sensitivity, highlighting its role in mitigating climate change.     

紫外线-B辐射与3种植物幼苗的光合作用——光合作用对紫外线-B敏感性的比较

紫外线 - B辐射降低豌豆、大豆和黄瓜 3种植物幼苗的净光合作用速率 ( Pn)和表观量子效率 ( AQE) ,Pn和 AQE的减少幅度随紫外线 - B辐射时间的延长逐渐增大。 3种植物的光合作用对紫外线 - B辐射的敏感性依次为 :豌豆 >黄瓜 >大豆 ,光合作用光抑制的发生程度与光合作用对 UV- B辐射敏感性有内在联系。定量分析显示 ,光合作用光抑制的发生程度随UV- B辐射时间增加 ,是 UV- B辐射剂量的累积效应。     

胃癌患者胃粘膜无芽胞厌氧菌分析及药物敏感试验

对98例具有消化不良症状的患者做胃镜检查,取胃粘膜组织进行细菌分离培养,结果表明,不同的消化道疾病,胃粘膜微生物群均发生不同的改变,其中胃癌患者改变最明显,胃内微生物检出率最高,无芽胞厌氧菌检出率87.88％（29／33）,其中产亚硝酸优杆菌检出率为57.60％（19／33）,硝酸盐还原试验阳性菌株占72.70％（24／33）。这些细菌和胃癌的关系有待深入研究。对19株产亚硝酸优杆菌做药物敏感试验,结果显示,该菌对青霉素类药物均耐药,对氯霉素,红霉素,庆大霉素敏感。     

Short-term nitrogen fertilization decreased root and microbial respiration in a young Cunninghamia lanceolata plantation

Aims As the primary pathway for CO₂ emission from terrestrial ecosystems to the atmosphere, soil respiration is estimated to be 80 Pg C·a^-1 to 100 Pg C·a^-1, equivalent to 10 fold of fossil fuel emissions. As an important management practice in plantation forests, fertilization does not only increase primary production but also affects soil respiration. To investigate how nitrogen (N) fertilization affects total soil, root and microbial respiration, a N fertilization experiment was conducted in a five-year-old Cunninghamia lanceolata plantation in Huitong, Hunan Province, located in the subtropical region. MethodsOne year after fertilization, soil respiration was monitored monthly by LI-8100 from July 2013 to June 2014. Soil temperature and water content (0-5 cm soil depth) were also measured simultaneously. Available soil nutrients, fine root biomass and microbial communities were analyzed in June 2013. Important findings Total soil, root and microbial respiration rates were 22.7%, 19.6%, and 23.5% lower in the fertilized plots than in the unfertilized plots, respectively. The temperature sensitivity (Q₁₀) of soil respiration ranged from 1.81 to 2.04, and the Q₁₀ value of microbial respiration decreased from 2.04 in the unfertilized plots to 1.84 in the fertilized plots. However, neither the Q₁₀ value nor the patterns of total soil respiration were affected by N fertilization. In the two-factor model, soil temperature and moisture accounted for 69.9%-79.7% of the seasonal variations in soil respiration. These results suggest that N fertilization reduces the response of soil organic carbon decomposition to temperature change and may contribute to the increase of soil carbon storage under global warming in subtropical plantations.     

南方丘陵山区生态安全格局构建与优化修复——以瑞金市为例

构建科学合理的生态安全格局、落实生态保护修复与空间优化是促进区域生态系统健康运行和社会经济可持续发展的重要途径。以南方丘陵山区瑞金市为例,综合生态敏感性评价与最小阻力模型,解构瑞金市生态安全格局及其自然生态与社会经济特点,并提出生态保护修复与空间优化方案。结果显示：(1)瑞金市生态源地共有123.22km~2,占总国土面积5%,主要为重要山林地和水域,环绕中部盆地呈卫星状分布;(2)潜在廊道119条,生态节点72个,在周边山地呈闭合网络状,但中部盆地廊道单一、节点密集,网络连通性较低;(3)瑞金市是典型的高原型阻力面,中部盆地城镇发展区、沟域经济延伸带、西部工矿挖采点生态阻力高、源地辐射弱,应生态预警与重点修复。瑞金市生态保护修复与空间优化应宏观统筹、分区推进、精细落实,划分生态修复核心区、生态监测预警区、生态保护缓冲区和生态保护重点区,明确空间管控原则、分区推进生态保护,围绕“源地-廊道-节点”落实生态修复。     

Variation in thermal sensitivity of performance among colour morphs of a pygmy grasshopper

Populations of pygmy grasshoppers, Tetrix subulata, display genetically coded discrete variation in colour pattern and there are differences among morphs in the capacity to achieve body heating. To determine whether colour morphs differ in thermal physiology, I assessed reaction distance and jumping performance of individuals belonging to different morphs at two different temperatures. Individuals allowed a potential predator to approach less closely and jumped longer distances at high than at low temperature. My analyses also uncovered variation among morphs in average reaction distance and jumping capacity, as well as in thermal sensitivity of these two traits. Matrix correlation analysis further revealed that pair-wise differences between morphs in thermal sensitivity of jumping performance (but not reaction distance) could be accurately predicted by differences in body temperatures preferred in a laboratory thermal gradient. These results support the view that morphology, behaviour and thermal physiology of ectotherms may evolve in concert. The relationship between reaction distance and jumping performance varied among colour morphs at high temperature, and the common within-morph relationship between these two traits deviated from the corresponding among-morph relationship. This suggests that the variation among morphs has partially arisen through active divergence, with selection having influenced both traits and modifications having occurred to different degrees in different morphs. My data further suggest that pale colour morphs, with a limited capacity to attain high body temperatures, may not necessarily be at a selective disadvantage, because their physiology may be adapted to lower body temperatures.     

Influence of inorganic phosphate and energy state on force in skinned cardiac muscle from freshwater turtle and rainbow trout

Inorganic phosphate, which increases in the hypoxic cardiac cell, depresses force development. The cardiac muscle of freshwater turtle maintains a remarkably high contractility during hypoxia; this may involve a low sensitivity to phosphate. Therefore, freshwater turtle and rainbow trout were compared with regard to Ca²⁺-activated force in skinned atrial trabeculae in a bath containing 3 mM ATP buffered by 15 mM creatine phosphate in the presence of creatine kinase. For turtle, an increase in phosphate from 0 mM to either 6 mM or 12 mM reduced maximal force by 50% and 80% respectively, whereas the Ca²⁺ activity eliciting half maximal force (Ca_0.5) was increased by 70% in 6 mM and could not be reliably recorded in 12 mM. For trout, the effects of phosphate were less pronounced. An increase from 0 mM to 12 mM did not affect maximal force significantly, but elevated Ca_0.5 by 70%. Hypoxia increases ADP as creatine phosphate is shifted to creatine, therefore, creatine phosphate was changed from 15 mM to 3 mM and creatine from 0 mM to 12 mM. After these changes, the elevation of phosphate from 0 mM to 12 mM had no significant effects for either turtle or trout. In conclusion, the high performance of turtle cardiac muscle during hypoxia does not involve a low sensitivity of the contractile system to phosphate. In addition, the effect of increased phosphate seems to be offset by a concomitant increase in ADP. Accepted: 28 June 1999