冷鲜牛肉中蜂房哈夫尼亚菌(Hafnia alvei)的分离与鉴定

在出口冷鲜牛肉的沙门氏菌检验过程中,从HE琼脂平板上分离到1株蜂房哈夫尼亚菌,该菌三糖铁斜面产碱,底层产酸,不产生H2S,不产气,革兰阴性。经BBL Crystal微生物半自动检测仪检测,同时结合伯杰细菌鉴定手册的生化试验结果鉴定为蜂房哈夫尼亚菌(Hafnia alvei)。     

Lipopolysaccharide core region of Hafnia alvei: Serological characterization

Abstract Covalent glycoconjugates containing, as a ligand lipopolysaccharide core, oligosaccharides of Hafnia alvei standard strain ATCC 13337 and R mutant 1 M were used to produce anti- H. alvei core antibodies. The sera obtained were tested in rocket immunoelectrophoresis, immunoblotting and ELISA using H. alvei lipopolysaccharides of various strains. The experiments were carried out to study the antigenic relationships between lipopolysaccharide core regions in the H. alvei genus.     

肠道哈夫尼菌促进黑腹果蝇的发育

目的 分离和鉴定黑腹果蝇肠道共生微生物,并研究其促进果蝇身体发育的功能。方法 利用Hungate滚管技术,分离厌氧细菌;运用定植实验证明其为果蝇肠道共生菌;用悉菌实验来检测细菌对果蝇发育的影响。结果 本研究从野外捕获的果蝇体内分离到蜂房哈夫尼菌（Hafnia alvei）,而且证实它能够在果蝇肠道内有效地定植并且能在培养基中稳定持续地存在,说明蜂房哈夫尼菌是果蝇肠道共生菌。此外,蜂房哈夫尼菌能显著地缩短无菌果蝇的发育周期及提高生长速率。结论 证明了蜂房哈夫尼菌是果蝇肠道的共生菌,并且其可以有效地促进果蝇的生长发育。     

The sensitivity of Hafnia alvei strains to the bactericidal effect of serum

Abstract Most Hafnia alvei strains are sensitive to the bactericidal action of normal bovine serum (NBS) as well as to a serum in which the alternative pathway of complement activation has been thermally blocked. Introduction of polysaccharides (PS) to NBS lowers the bactericidal effect. In a serum in which the alternative pathway of complement activation is blocked, PS completely cancels the bacterial effect.     

Structure of the O-specific polysaccharide of Hafnia alvei PCM 1196

An acidic O-specific polysaccharide was isolated from Hafnia alvei PCM 1196 lipopolysaccharide and studied by sugar and methylation analyses along with one- and two-dimensional 1H and 13C NMR spectroscopy, including NOESY and HMBC experiments. The following structure of the pentasaccharide repeating unit was established: -->4)-alpha-D-GalpA-(1-->3)-beta-D-GlcpNAc-(1-->2)-beta-D-Galp-(1-->6)-alpha-D-Glcp-(1-->6)-alpha-D-GlcpNAc-(1-->.     

Non-typical lipopolysaccharide core regions of some Hafnia alvei strains: structural and serological studies

The lipopolysaccharides of Hafnia alvei strains 23, 1222 and 39 were found to have non-typical core region. On the basis of sugar and methylation analyses, 1H-nuclear magnetic resonance spectra and matrix-assisted laser-desorption ionization-time of flight mass spectrometry, it was concluded that the core oligosaccharide of strains 23 and 1222 has the same structure as Escherichia coli R4 core region, and the core oligosaccharide of strain 39 has the structure of Salmonella Ra core. Using the serological methods (passive hemagglutination, enzyme-linked immunosorbent assay and immunoblotting) and the anti-conjugate sera directed against E. coli R4 and Salmonella Ra core oligosaccharides we have confirmed the structural results presented above.     

Invasion and intracellular survival of Hafnia alvei strains in human epithelial cells

Aims: The aim of this study was to investigate the invasion and intracellular survival of different Hafnia alvei strains in HeLa cells. Methods and Results: We performed different experiments on the bacterial invasion of different strains of H. alvei into the HeLa cell line using gentamicin protection assays and immunofluorescence. We also report the time course of cell internalization and the effects of inhibitors on the invasion of H. alvei. Levels of invasion varied depending on the conditions (strain, time and inoculum size) used. Conclusions: This study revealed that H. alvei strains were able to enter and persist in a human epithelial cell line. Significance and Impact of the Study: Our in vitro findings highlight the possibility that some H. alvei strains may exploit nonprofessional phagocytes or nonphagocytic cells to spread in vivo, which may be important for the persistence and establishment of an asymptomatic carrier state.     

Serological and structural features of Hafnia alvei lipopolysaccharides containing d-3-hydroxybutyric acid

Abstract The serological heterogeneity of Hafnia alvei lipopolysaccharides from strains ATCC 13337, 1187, 1221, 114/60, 1211 and 1216, that contain d -3-hydroxybutyric acid, was analyzed by rocket immunoelectrophoresis, immunoblotting and passive hemagglutination. The significance of d -3-hydroxybutyric acid component for their cross-reactivity has been discussed. The results obtained allowed us to place four H. alvei strains (ATCC 13337, 1187, 1221 and 114/60) in one serotype (A) and to consider two other strains (1211 and 1216) as separate serotypes (B and C, respectively).     

Structures of the biological repeating units in the O-chain polysaccharides of Hafnia alvei strains having a typical lipopolysaccharide outer core region

Earlier, the structures of the O-chain polysaccharides of the lipopolysaccharides (LPS) of a number of Hafnia alvei strains have been established. However, it remained unknown, which is the first and the last monosaccharide of the O-chain. This is defined by the structure of the so-called biological repeating unit (O-unit), which is pre-assembled and then polymerised in the course of biosynthesis of bacterial polysaccharides by the Wzy-dependent pathway. Now we report on the structures of the O-units in 10 H. alvei strains. The LPS were cleaved by mild acid hydrolysis and oligosaccharide fractions IIIa and IIIb were isolated by gel chromatography subsequently on Sephadex G-50 and BioGel P-2 and studied by methylation analysis and NMR spectroscopy. Fraction IIIb was found to represent the core oligosaccharide containing a terminal upstream alpha-d-Glc-(1-->3)-alpha-d-Glc or alpha-d-Gal-(1-->3)-alpha-d-Glc disaccharide in the outer region that is typical of H. alvei. Fraction IIIa consists of the LPS core with one O-unit linked by a 3-substituted beta-d-GalNAc residue (in strains PCM 1189 and PCM 1546) or a 3-substituted beta-d-GlcNAc residue (in the other strains studied). In most strains examined the beta-configuration of the d-GlcNAc linkage in the first O-unit attached to the core is the same and in some strains is opposite to that found in the interior O-units of the O-chain polysaccharide. Various monosaccharides, including d-Glc, d-Gal, d-GlcA and acyl derivatives of 3-amino-3,6-dideoxy-d-glucose or 4-amino-4,6-dideoxy-d-glucose, occupy the non-reducing end of the O-unit.     

Structural and serological studies on Hafnia alvei O-specific polysaccharide of alpha-D-mannan type isolated from the lipopolysaccharide of strain PCM 1223

On the basis of chemical and methylation analyses, one- and two-dimensional (1)H- and (13)C-NMR spectroscopy, including COSY, TOCSY, NOESY and (1)H, (13)C HSQC experiments, a neutral O-specific polysaccharide isolated from Hafnia alvei strain PCM 1223 lipopolysaccharide (LPS) was found to be an alpha-mannan composed of pentasaccharide repeating units having the following structure:-->3)-alpha-D-Manp-(1-->3)-alpha-D-Manp-(1-->2)-alpha-D-Manp-(1-->2)-alpha-D-Manp-(1-->2)-alpha-D-Manp-(1-->. Immunoblotting showed a strong cross-reactivity between anti-H. alvei PCM 1223 serum and LPSs of Escherichia coli O9 and Klebsiella pneumoniae O3. The serological relationship of the LPSs of these bacteria is due to the structural identity of their O-specific polysaccharides, though the LPSs differ in their core regions.     

Hafnia alvei lipopolysaccharides: Isolation, sugar composition and SDS-PAGE analysis

Abstract Lipopolysaccharides (LPS) of 33 strains of Hafnia alvei were isolated and purified. LPS content of the dry bacterial mass ranged from 1.2 to 4.5%. All examined lipopolysaccharides contained glucose, glucosamine, heptose, 3-deoxy-octulosonic acid and often galactose. Rhamnose, mannose, galactosamine, mannosamine and unidentified amino sugars were found in some H. alvei strains. Sialic acid was present in LPS of one strain. d -3-Hydroxybutyryl groups also were identified in lipopolysaccharides of 5 strains of this genus.
SDS-PAGE of the lipopolysaccharides was presented in the paper. According to these results two core types exist in H. alvei .     

Structure of the O-polysaccharide from the lipopolysaccharide of Hafnia alvei strain PCM 1529

The following structure of the pentasaccharide repeating unit of an acidic O-polysaccharide of Hafnia alvei PCM 1529 was established by sugar and methylation analyses along with 1D and 2D 1H and 13C NMR spectroscopy: [Carbohydrate structure: see text].     

诱导蜂房哈夫尼菌产L-赖氨酸脱羧酶条件的研究

用响应面法对蜂房哈夫尼菌（Hafnia alvei）L-赖氨酸脱羧酶产酶诱导条件进行优化。首先通过单因素实验对产酶体系的pH、震荡培养时间、静置培养时间、诱导物添加量和Ⅷ添加量进行优化。在此基础上,用部分因子重复试验筛选出对酶活影响显著的3个因素（静置培养时间,诱导物添加量,VB6添加量）,再通过Box-behnken实验对这三个因素进行优化,得出最优值。最终得到产酶最佳诱导条件为：震荡培养阶段培养基pH6．5,静置培养阶段pH5．5;摇床震荡培养11h后静置培养7．5h,诱导物L一赖氨酸加入量为5．18dL,维生素B6加入量为1．38g／L时酶活最高,达到71．2U／mL,为优化前（1．74u／mL）的41．8倍,在单因素的基础上提高了19％。     

Structure of the O-polysaccharide from the lipopolysaccharide of Hafnia alvei strain PCM 1546

An acidic O-polysaccharide isolated by mild acid hydrolysis from the lipopolysaccharide of Hafnia alvei PCM 1546 is composed of D-Gal, D-Glc, D-GlcA, D-GalNAc and O-acetyl groups in the ratios 1:1:1:2:1.6. On the basis of sugar and methylation analyses along with 1D and 2D 1H and 13C NMR spectroscopy, the following structure of the pentasaccharide repeating unit of the polysaccharide was established: [see equation in text].     

Structure of the O-polysaccharide of Hafnia alvei strain PCM 1189 that has hexa- to octasaccharide repeating units owing to incomplete glucosylation

The O-polysaccharide of Hafnia alvei PCM 1189 consists of D-glucose, D-galactose, D-GalNAc and D-GlcA and lacks the strict regularity. The intact and carboxyl-reduced polysaccharides as well as oligosaccharides obtained by partial acid hydrolysis were studied by chemical and enzymatic analyses, methylation and NMR spectroscopy. The following structure was established for the O-polysaccharide, which is built up of branched hexa- to octasaccharide repeating units differing in the number of lateral glucose residues: [structure: see text] where the glucose residues shown in italics are nonstoichiometric substituents. The repeating units include also a minor O-acetyl group, whose position was not determined.     

Genetic structure and ecological niche segregation of Indian gray mongoose (Urva edwardsii) in Iran

Combining genetic data with ecological niche models is an effective approach for exploring climatic and nonclimatic environmental variables affecting spatial patterns of intraspecific genetic variation. Here, we adopted this combined approach to evaluate genetic structure and ecological niche of the Indian gray mongoose (Urva edwardsii) in Iran, as the most western part of the species range. Using mtDNA, we confirmed the presence of two highly differentiated clades. Then, we incorporated ensemble of small models (ESMs) using climatic and nonclimatic variables with genetic data to assess whether genetic differentiation among clades was coupled with their ecological niche. Climate niche divergence was also examined based on a principal component analysis on climatic factors only. The relative habitat suitability values predicted by the ESMs for both clades revealed their niche separation. Between‐clade climate only niche comparison revealed that climate space occupied by clades is similar to some extent, but the niches that they utilize differ between the distribution ranges of clades. We found that in the absence of evidence for recent genetic exchanges, distribution models suggest the species occurs in different niches and that there are apparent areas of disconnection across the species range. The estimated divergence time between the two Iranian clades (4.9 Mya) coincides with the uplifting of the Zagros Mountains during the Early Pliocene. The Zagros mountain‐building event seems to have prevented the distribution of U. edwardsii populations between the western and eastern parts of the mountains as a result of vicariance events. Our findings indicated that the two U. edwardsii genetic clades in Iran can be considered as two conservation units and can be utilized to develop habitat‐specific and climate change‐integrated management strategies.     

The O-acetylation patterns in the O-antigens of Hafnia alvei strains PCM 1200 and 1203, serologically closely related to PCM 1205

Serological tests revealed immunochemical similarities between the lipopolysaccharides of Hafnia alvei strains PCM 1200, 1203 and 1205. Immunoblotting and ELISA showed cross-reactions between the strains. NMR spectroscopy showed that the O-deacetylated O-specific polysaccharides isolated from lipopolysaccharides of H. alvei strains PCM 1200 and 1203 possessed the same composition and sequence as the O-deacetylated O-specific polysaccharide of H. alvei strain PCM 1205, that is a glycerol teichoic-acid-like polymer with a repeating unit of the following structure: [carbohydrate structure: see text] NMR spectroscopic studies of the polysaccharides concluded that O-3 of the side chain beta-D-GlcpNAc is partially O-acetylated (50-80%) in both investigated strains. In strain PCM 1203 an additional O-acetyl group (50-80%) is linked to O-6 of the chain -->3)-alpha-D-GlcpNAc-(1--> residue. The structural features of the isolated O-specific polysaccharides were also the same as those of the O-specific polysaccharides on the bacterial cells directly observed by the HR-MAS NMR technique.     

Livestock grazing and forest structure regulate the assembly of ecological clusters within plant networks in eastern Australia

Questions

How do changes in grazing intensity by different herbivores and differences in forest structure affect the assembly of ecological clusters within plant ecological networks in dryland plant communities?

Location

Eastern Australia across an area of 0.4 million km².

Methods

We used correlation network analysis and structural equation modelling to examine how changes in grazing intensity, by different herbivores, and differences in forest structure (tree canopy cover, basal area and density) and soil fertility influenced the assembly of ecological clusters of plant communities (i.e. relative abundance of ecological clusters formed by co‐occurring plant species within an ecological network) in three forested communities from eastern Australia.

Results

Livestock grazing and forest structure regulated the relative abundance of ecological clusters within plant networks, but their effects on these plant assemblies were highly dependent on the ecological cluster and forest community type, with no single winner or loser across forest types, conditions or grazing intensities. Thus, the relative abundance of some ecological clusters increased under grazing while others declined, a response that was maintained across different forest structures. The relative importance of grazing, forest structure and soil fertility varied across forest community type. The two eucalypt communities exhibited mixed effects of grazing and forest structure (Eucalyptus largiflorens ) or forest structure only (Eucalyptus camaldulensis ). In the third (Callitris glaucophylla ) community, grazing played a larger role in controlling the plant community assembly. Soil fertility (soil C and P) effects were of a similar magnitude to grazing and forest structure, but the effects differed among clusters.

Conclusions

Livestock grazing and forest structure regulated the relative abundance of ecological clusters within networks of plant communities in forests in eastern Australia. Our study uses a novel approach of ecological clusters to show that differences in grazing and forest structure will always disadvantage some plant ecological clusters. Furthermore, changes in one cluster will ultimately affect other clusters. Any changes in management therefore will have varied effects on different ecological plant clusters.

     

野古草种群克隆的遗传变异和遗传结构

用酶电泳法和同工酶分析对东北松嫩草原西北部野古草种群克隆遗传变异性和种群遗传结构做了探讨。讨论了遗传多样性、地理距离和遗传距离之间的关系、大种群和小种群的遗传变异性和种群间的基因流 ;种群间 ,包括大种群和小种群间基因流、遗传和地理距离对遗传多样性的影响、昆虫和风传粉、种群籽苗的补充、遗传多样性的发生和保持 ,自交不亲和性和无性繁殖及体细胞突变