成团肠杆菌的生物功能多样性及其分类最新进展

综述了成团肠杆菌的生物功能多样性及其在分类上的最新进展。在生物代谢途径方面具有脱卤素、降解三硝酸甘油及将甘油转化为 1,3 丙二醇的能力。同时 ,成团肠杆菌还具有溶磷、固氮能力、分泌植物激素及各种酶类 ,因此在植物促生方面具有潜在的应用价值。成团肠杆菌是一个比较异源的菌群 ,它的分类地位还没有最后确定 ,现已将其中部分菌群重新命名为泛菌属 ,其中模式菌株为成团泛菌     

Innate endogenous adjuvants prime to desirable immune responses via mucosal routes

Vaccination is an effective strategy to prevent infectious or immune related diseases, which has made remarkable contribution in human history. Recently increasing attentions have been paid to mucosal vaccination due to its multiple advantages over conventional ways. Subunit or peptide antigens are more reasonable immunogens for mucosal vaccination than live or attenuated pathogens, however adjuvants are required to augment the immune responses. Many mucosal adjuvants have been developed to prime desirable immune responses to different etiologies. Compared with pathogen derived adjuvants, innate endogenous molecules incorporated into mucosal vaccines demonstrate prominent adjuvanticity and safety. Nowadays, cytokines are broadly used as mucosal adjuvants for participation of signal transduction of immune responses, activation of innate immunity and polarization of adaptive immunity. Desired immune responses are promptly and efficaciously primed on basis of specific interactions between cytokines and corresponding receptors. In addition, some other innate molecules are also identified as potent mucosal adjuvants. This review focuses on innate endogenous mucosal adjuvants, hoping to shed light on the development of mucosal vaccines.     

In Vitro Adsorption Revealing an Apparent Strong Interaction Between Endophyte <Emphasis Type="Italic">Pantoea agglomerans</Emphasis> YS19 and Host Rice

Pantoea (formerly Enterobacter) agglomerans YS19 is a dominant diazotrophic endophyte isolated from rice (Oryza sativa cv. Yuefu) grown in a temperate-climate region in west Beijing, China. In vitro adsorption and invasion of YS19 on host plant root were studied in this research. Adsorption of YS19 on rice seedling roots closely resembled the Langmuir adsorption and showed a higher adsorption quantity than the control strains Paenibacillus polymyxa WY110 (a rhizospheric bacterium from the same rice cultivar) and Escherichia coli HB101 (a general model bacterium). Adsorption dynamics study revealed high rates and a long duration of the YS19-rice root adsorption process. Adsorption of YS19 was mainly observed on the root hair, though which it enters the plant. This in vitro adsorption study revealed an apparent strong interaction between YS19 and rice at the early endophyte-host recognition stage.     

Opioidergic modulation of cocaine conditioned place preferences.

Recent studies have begun to assess the utility of opioid agonists and antagonists for the treatment of cocaine addiction. The present studies assess the effects of naltrexone or methadone on cocaine's reinforcing properties using the conditioned place preference (CPP) test. The results indicate that a 56 mg/kg dose of naltrexone, given 4 hr prior to conditioning, attenuates cocaine's CPP. In contrast, methadone (8 mg/kg), given 1 hr prior to conditioning, enhanced cocaine's reinforcing properties. These results support the suggestion that opioid antagonists may have clinical utility in treating cocaine addiction. The results with methadone lead to a possible explanation for the higher rates of cocaine use in methadone-treated heroin addicts.     

丁氟螨酯对二斑叶螨生长发育的影响

[目的]丁氟螨酯是一种新型酰基乙腈类非内吸性杀螨剂,对害螨的各个螨态都有很高活性,具有较高的应用价值.本文评价了丁氟螨酯对二斑叶螨生长发育的影响,以期为合理用药和二斑叶螨的综合防治提供理论依据.[方法]采用浸叶法测定丁氟螨酯对二斑叶螨成螨与卵的致死中浓度、雌成螨产卵量、各螨态存活率以及各发育历期的影响.[结果]经丁氟螨...     

硝化抑制剂对蔬菜土硝化和反硝化细菌的影响

土壤N素循环主要是微生物驱动的转化过程,然而对其的驱动与调控机理了解还很不够。选取长沙黄兴镇蔬菜基地两种蔬菜土研究硝化抑制剂(DCD)对N素转化过程及功能微生物的影响。试验通过室内土壤培养,处理为单施尿素(CK)和尿素与硝化抑制剂双氰胺配合施用(DCD),重复3次。在培养过程中系统监测了土壤中NH₄⁺-N、NO₃^--N含量变化,同时采用荧光定量PCR(real-time PCR)方法研究硝化抑制剂对土壤中氮素转化功能基因丰度的影响。结果表明:在培养过程中DCD处理使两个供试土壤的NH₄⁺浓度稳定在较高水平,而NO₃^-浓度则明显低于对照;施用DCD导致土壤中硝化基因amoA丰度显著减少,而对16S rRNA和反硝化基因nirK丰度没有产生明显影响。因此,DCD在菜地土壤中主要通过抑制氨氧化细菌的繁衍来抑制硝化作用。     

Comparative analysis of methane-oxidizing archaea and sulfate-reducing bacteria in anoxic marine sediments

The oxidation of methane in anoxic marine sediments is thought to be mediated by a consortium of methane-consuming archaea and sulfate-reducing bacteria. In this study, we compared results of rRNA gene (rDNA) surveys and lipid analyses of archaea and bacteria associated with methane seep sediments from several different sites on the Californian continental margin. Two distinct archaeal lineages (ANME-1 and ANME-2), peripherally related to the order Methanosarcinales, were consistently associated with methane seep marine sediments. The same sediments contained abundant (13)C-depleted archaeal lipids, indicating that one or both of these archaeal groups are members of anaerobic methane-oxidizing consortia. (13)C-depleted lipids and the signature 16S rDNAs for these archaeal groups were absent in nearby control sediments. Concurrent surveys of bacterial rDNAs revealed a predominance of delta-proteobacteria, in particular, close relatives of Desulfosarcina variabilis. Biomarker analyses of the same sediments showed bacterial fatty acids with strong (13)C depletion that are likely products of these sulfate-reducing bacteria. Consistent with these observations, whole-cell fluorescent in situ hybridization revealed aggregations of ANME-2 archaea and sulfate-reducing Desulfosarcina and Desulfococcus species. Additionally, the presence of abundant (13)C-depleted ether lipids, presumed to be of bacterial origin but unrelated to ether lipids of members of the order Desulfosarcinales, suggests the participation of additional bacterial groups in the methane-oxidizing process. Although the Desulfosarcinales and ANME-2 consortia appear to participate in the anaerobic oxidation of methane in marine sediments, our data suggest that other bacteria and archaea are also involved in methane oxidation in these environments.     

Colonization of endophyte <Emphasis Type="Italic">Pantoea agglomerans</Emphasis> YS19 on host rice,with formation of multicellular symplasmata

Pantoea agglomerans YS19 is a diazotrophic endophyte isolated from rice (Oryza sativa cv. Yuefu) grown in a temperate-climatic region in west Beijing (China). The colonization of YS19 on host rice was studied in this paper. It was revealed that YS19 colonizes in all the tissues of rice seedlings, including roots (dominantly at elongation regions, lateral root junctions, root hairs and root caps), stems and leaves. More YS19 colonizes in stem and leaves (1.40 × 10⁵ CFU mg⁻¹ fresh weight) than that in roots (3.60 × 10⁴ CFU mg⁻¹). Symplasmata, a kind of adaptive structure of the strain for its endophytic living, were repeatedly observed to form inside root or stem cortex parenchyma tissues, as well as on leaf surfaces and also rhizoplanes. A novel matrix protein (SPM43.1) with its expression paralleling to the formation of symplasmata was captured, whose meaning in structural construction of symplasmata was also discussed.     

番茄、玉米套种膜下滴灌条件下农田地温变化特征

土壤水热状况是影响作物生长的重要因素,以膜下滴灌及套种双重效应为背景,针对番茄、玉米套种农田设置了高(番茄:180 mm,玉米:270 mm)、中(番茄:132 mm,玉米:202.5 mm)、低(番茄:84 mm,135 mm)3种不同的灌溉定额,采用定位监测法测定番茄带膜间裸地(A)、覆膜番茄行间(B)、番茄带与玉米带膜间裸地(C)、覆膜玉米行间(D)共4个位置的不同深度主根区含水率和地温动态变化,研究了地膜覆盖、土壤水分以及作物遮阴对套种农田不同行间,不同深度土壤温度的影响特征。结果表明:全生育期内,4个水平位置的地温大小顺序与土壤深度有关,10 cm以上的地温大小顺序为CDAB,10 cm以下的地温大小顺序为DBAC;从土壤温度场的分布情况来看,地温的最大变幅出现在C处,为8.10℃;最小变幅出现在B处,为4.71℃;含水率与地温的关系表现为:5 cm以上地温与含水率呈反比关系,20 cm以下地温与含水率呈正比关系。可见,套种覆膜滴灌农田合适的土壤水分状况将有利于根区良好水热的形成,从而更有利于作物的生长。研究结果将对西北地区滴灌农田管理有一定的参考价值。