Colonization of Butchers with Livestock‐Associated Methicillin‐Resistant Staphylococcus aureus

Reports have documented colonization of swine in Europe, North America and more recently in China with livestock‐associated methicillin‐resistant Staphylococcus aureus (LA‐MRSA). Contamination of pig farmers, veterinarians and abattoir workers with these strains has been observed. However, although contamination levels of 10% of retail pork were reported from the Netherlands and Canada, there are limited data of contamination rates of workers handling raw meat. We investigated the rates of MRSA contamination of local butchers working in wet markets, where recently slaughtered pigs are cut up. Nasal swabs collected from 300 pork butchers at markets throughout Hong Kong were enriched in brain heart infusion broth with 5% salt and cultured on MRSASelect^®. Isolates were confirmed as Staphylococcus aureus and susceptibility testing performed. The presence of mecA was confirmed, SCCmec and spa type determined and relatedness investigated by PFGE. Subjects completed a questionnaire on MRSA carriage risk factors. Seventeen samples (5.6%) yielded MRSA, 15 harbouring SCCmec IVb. Ten strains were t899 (CC9), previously reported from local pig carcasses. Five strains were healthcare associated: SCCmec type II, t701(CC6), colonizing two subjects at the same establishment, and single isolates of t008 (CC8), t002 (CC5) and t123 (CC45). The remaining isolates were t359 (CC97), previously reported from buffaloes, and t375 (CC5), reported from bovine milk. None of these butchers reported recent hospitalization or a healthcare worker in the family. Two had recently received antibiotics, one for a skin infection. Four reported wound infections within the last year. All were exposed to meat for >9 h per day. Carriage of MRSA was higher in butchers than in the general community. Although five strains were probably of healthcare origin, the high incidence of t899 (CC9) suggests that cross‐contamination from pork occurs frequently. Washing of hands after touching raw pork is advised.     

早期营养干预对幼龄反刍动物瘤胃微生物区系发育的影响

正常稳定的瘤胃微生物区系是反刍动物瘤胃健康的重要指标,且在瘤胃结构形态发育、微生物定植模式、免疫功能调节及抵御外源致病因子侵袭等方面发挥着重要积极作用.最近研究表明,新生反刍动物瘤胃微生物组成相对单一,但随着早期瘤胃发育过程中不同微生物群落相继开始定植并占据不同的生态位,此时的营养干预可能会形成特定的微生物群落组合并产...     

致仔猪水肿病大肠杆菌减毒株的毒力测定及其在仔猪肠道内增殖的分析

在已构建致仔猪水肿病大肠杆菌S451521菌株的2个毒素敲除菌株（F1、F2）基础上,进一步测定了其毒力及在仔猪肠道内的繁殖能力。选择30日龄的ICR小鼠并随机分成4组,A、B、C试验组分别灌胃接种不同浓度的野生菌株S451521及其毒素敲除菌株F1、F2,D组以灭菌生理盐水作阴性对照;结果表明减毒菌株F1和F2毒力均比野生菌株弱,其中F1株减弱了60.73%、F2株减弱了84.38%。选择24日龄未经仔猪水肿病疫苗免疫过的仔猪共14头,并随机分为2组;第1组口服接种减毒菌株F2,第2组以灭菌生理盐水作阴性对照,定期采集仔猪粪样并进行细菌监测;结果显示,仔猪排出减毒菌株F2的数量随时间不断增多,在接种后28d可达到每克粪样含目的菌约70 000cfu。这说明减毒菌株F2能够在仔猪体内定植并大量繁殖。     

Macroinvertebrate frequency data for the RIVPACS III sites in Northern Ireland and some comparisons with equivalent data for Great Britain

1. A total of 313 macroinvertebrate taxa were recorded from the 70 running‐water sites in the R iver I nV ertebrate P rediction A nd C lassification S ystem (RIVPACS III) dataset for Northern Ireland, after the application of a standardization procedure to ensure that all samples were identified to the same taxonomic level. The listing includes a small number of oligochaetes not previously reported from Ireland. The frequency of occurrence of the 313 taxa within the Northern Ireland dataset is also presented. 2. The taxonomic composition and frequency of occurrence of taxa in the Northern Ireland dataset were then compared with the 614 site dataset for Great Britain, which included 637 taxa, and a 75 site subset within Britain at a similar latitude to Northern Ireland with 333 taxa. 3. The macroinvertebrate fauna of Northern Ireland is dominated by taxa recorded at the highest frequencies of occurrence in Britain. Some notable absences are highlighted and, in particular, a small number of lotic mayflies and stoneflies which are common in Great Britain. There is documentary evidence of the introduction by man of a number of non‐insect taxa, either deliberately or by accident. 4. A detailed knowledge of the present composition of the macroinvertebrate fauna of running‐water sites in Northern Ireland, and an active research programme on the potential for new colonists to pose a threat to native species, are important factors in the future conservation of the freshwater fauna. Copyright © 2000 John Wiley & Sons, Ltd.     

Source of mycorrhizal inoculum influences growth of Faidherbia albida seedlings

Poor land use management and practice inhibit the growth and establishment of tree seedlings in dryland areas.We assessed arbuscular mycorrhizal fungi(AM)status of Faidherbia albida(Del.)A.Chev.trees grown on different land uses.We quantified the growth and nutrient uptake of F.albida seedlings inoculated with AM from different sources.These efforts were based on soil and fine root samples from the rhizosphere soils of F.albida trees.AM root colonization was determined using the gridline intersect method.Spores were extracted by the wet sieving and decanting method and identified to genus level.The seedling experiment had a completely randomized onefactorial design with four treatments and five replications.Faidherbida albida seedlings were grown in a greenhouse.All in situ F.albida trees were colonized by AM fungi.AM root colonization of F.albida trees was significantly higher(P<0.0086)in area exclosures than on lands used for grazing or cultivation.Spore abundance was significantly higher(P<0.0014)in area exclosures followed by cultivated land and grazing land.Glomus was the dominant genus in all land-uses.AM-inoculated F.albida seedlings grew better(P<0.05)than non-inoculated controls.Seedlings inoculated with AM from area exclosure had significantly(P<0.05)higher growth and nutrient uptake than those inoculated with AM from grazing and cultivated land.This emphasizes the importance of the native soil AM potential for better establishment of seedlings to achieve optimum plant growth improvement and assist in rehabilitation of degraded arid lands.     

Arbuscular mycorrhizas and performance of Polylepis australis trees in relation to livestock density

Polylepis australis trees endemic to Argentina dominate the canopy of subtropical high altitude forests. Here, livestock rearing is the main economic activity and is suspect of the low performance of P. australis trees through direct and indirect effects which could include the reduction in arbuscular mycorrhizal fungi (AMF) and their benefit to trees. To elucidate the role of AMF, we compare plant performance indicators, arbuscular mycorrhizal (AM) colonization and AMF communities in 20 trees distributed in two areas of central Argentina which differed in livestock grazing intensity. The area with high livestock density presented more soil degradation and trees with a lower overall plant performance than the area with reduced livestock density. The AM colonization values of P. australis were considerably higher than reported for other tree species and the area with high livestock density had a lower proportion of arbuscules and higher proportion of hyphae, while vesicles and AM colonization – all structure considered together – did not differ between areas. Overall AMF spore number and of most species when considered separately was significantly higher in the area with high livestock density, suggesting a high tolerance and adaptation of AMF to livestock. We conclude that a reduction in livestock improves the performance of P. australis, that this improvement could be mediated by an increase in the proportion of arbuscules, but there does not appear to be any limitation in AM colonization or AMF spore number which could otherwise be limiting forest restoration.     

Functional compatibility of two arbuscular mycorrhizae with thirteen fruit trees in Senegal

Functional compatibility between thirteen tropical fruit trees (Afzelia africana Smith., Adansonia digitata L., Aphania senegalensis Radlk., Anacardium occidentale L., Cordyla pinnata (Lepr. ex A. Rich.) Milne-Redhead, Dialium guineensis Wild., Landolphia heudelottii A.DC., Sclerocarya birrea (A.Roch.) Hochst., Saba senegalensis (A. DC.) Pichon and four reference hosts Balanites aegyptiaca (L.) Del., Parkia biglobosa (Jacq.), Tamarindus indica L. and Zizyphus mauritiana Lam.) and two arbuscular mycorrhizal fungi (AMF) (Glomus aggregatum Schenck and Smith emend. Schenck and Glomus intraradices Schenck and Smith), was investigated. Marked differences were found between them in terms of mycorrhizal formation, root colonization, relative mycorrhizal dependency (RMD) and phosphorus concentrations in shoot tissues. A. africana, L. heudelottii and S. senegalensis did not form symbiotic associations, and the growth of A. africana decreased following mycorrhizal inoculation, while L. heudelottii and S. senegalensis showed no dependency. In contrast, A. digitata, A. senegalensis, A. occidentale, B. aegyptiaca and S. birrea were well colonized with AMF, but did not significantly increase in biomass production. Five fruit trees did, however, show dependency by a positive interaction with G. aggregatum, the most effective AMF. Z. mauritiana was found to be very highly dependent (RMD > 75%), T. indica was highly dependent (50–75% RMD), and D. guineensis, P. biglobosa and C. pinnata were moderately dependent (25–50% RMD). Phosphorus absorption probably contributed to this dependency more than the absorption of potassium. These results indicate that some tropical fruit trees do derive benefits from AM inoculation, while others do not.This revised version was published online in November 2005 with corrections to the Cover Date.     

印度梨形孢定殖策略和促生机制研究进展

为揭示印度梨形孢(Serendipita indica)与寄主植物共生及促生作用的原理,综述了印度梨形孢定殖策略和促生机制两个方面的研究进展。总结了印度梨形孢形态和功能特点;定殖的过程、策略及影响因素;促进寄主生长发育的作用及其机制。印度梨形孢在植物根系定殖进化出了高度特异性的策略,其梨形的厚垣孢子能够定殖在成熟的细胞中,但不会引起植物的胁迫,最终达到真菌定殖和植物生长的平衡状态。印度梨形孢定殖成功后发挥其生物生长调节器的作用,通过不同机制促进植物生长和花朵发育,提高种子、果实的产量和品质。指出研究印度梨形孢的定殖策略,需要综合宿主的生态学、生理学、遗传学和基因组学的框架;印度梨形孢促进植物生长发育的作用机制需要结合宏基因组等先进技术综合研究;印度梨形孢相关产品的开发需要考虑配方稳定性、产品产业化和保质期等问题。     

Precipitation as the most affecting factor on soil–plant environment conditions affects the mycorrhizal spore numbers in three different ecological zones in Turkey

Mycorrhizal symbiosis is the one of the most important relationship between microbiota and plants to sustain plant nutrition in relatively unfavourable conditions. Somehow this relation is threatened by time, therefore, definition of the factors effecting mycorrhizal symbiosis has become essential. The aim of this study was to determine the differences in specific mycorrhizal parameters such as sporulation and soil–plant environment conditions in three different regions of Turkey. During 1996?2002, 53 soil series were selected from natural and agricultural plant communities in three different agro-ecological zones of Turkey: Central Anatolia (CA), the Southeastern Anatolian (SA) project area and the Coast of Mediterranean (CM). The arbuscular mycorrhizal fungus (AMF), spore numbers and mycorrhizal root colonization were related to the annual average precipitation, soil characteristics and host plant identity.

In the CM zone (average annual precipitation of 650?mm), soils found under natural vegetation contained a maximum value of 108?spores?g^?1, with bare soils containing a minimum number of 0.1?spores?g^?1. In the CA zone (330?mm annual average precipitation), the maximum number of spores in the soil samples was 46.5?spores?g^?1 with a minimum of 6.8?spores?g^?1 and in the SA soil samples (380?mm annual average precipitation), a maximum of 48.4?spores?g^?1 and a minimum of 14.2?spores?g^?1 were recorded. The overall mean number of mycorrhizal spores g^?1 soil was 15.5?±?14.4, 22.2?±?8.6 and 27.9?±?25.4 for the CA, SA and CM zones, respectively. Mean spore numbers differed in only two of the three zones, with the third zone being intermediate. Precipitation was the most affecting factor on the sporulation of AMF. Also host plant species and certain soil parameters, such as positive correlations with CaCO₃ and N-min and a negative correlation with organic matter, have an influence on sporulation.

The key finding is that the cropping system has a large impact on spore numbers/abundance. Seventeen standing crops as well as bare soil, fallow and natural areas were compared. There are a large number of factors which can affect mycorrhizal development; in the present work, it seems that soil and crop management, and environmental factors (such as precipitation) affect sporulation and root colonization. Covering land surface with mycorrhiza-dependent cover crop, irrigation and less soil till may increase indigenous mycorrhizal spores.     

田菁茎瘤固氮根瘤菌在小麦体内的定殖及营养元素相关miRNA的表达

【目的】随着化肥过度使用引起的环境问题的出现,无公害农业的推广,以及新型肥料研究领域不断拓宽,微生物肥料,尤其是植物根际促生菌的研究成为近年来的热点。然而微生物肥料的增产机理还基本停留在作物农学性状的表观调查上,没有从分子水平进行研究。因此,本文用田菁茎瘤固氮根瘤菌（Azorhizobium caulinodans ORS571）侵染小麦,探索GFP-A.caulinodans在小麦幼苗组织中的分布与定殖规律以及营养元素相关miRNAs在小麦与A.caulinodans互作中的作用机制。【方法】使用A.caulinodans侵染小麦种子（品种为小偃22）,将接菌6 d后的小麦幼苗的根和接菌12 d后的叶制作玻片,利用激光共聚焦显微镜对样品进行逐层扫描,检测GFP-A.caulinodans在幼苗不同组织中的分布与定殖情况。同时,采集接菌后0 h、 6 h、 12 h、 24 h、 48 h、 72 h、 96 h的小麦幼根取样,用Trizol法提取总RNA。利用试剂盒进行加尾和反转录反应,将样品总RNA中的miRNA合成为cDNA,使用-tubulin作为内参基因,进行实时定量PCR反应,使用2-CT方法计算相对表达量。利用psRNATarget 在线软件,采用默认参数,对miRNA的靶基因进行预测。【结果】 1）激光共聚焦结果显示,GFP-A.caulinodans可定殖于根的表皮细胞、 细胞间隙、 根尖破损处和根毛,在根维管组织和叶片气孔部位,也发现有GFP-A.caulinodans存在。2）实时定量PCR分析结果表明,6条与营养元素代谢有关的miRNA表达发生变化,其中miR164、 miR167和miR827相对表达量呈现出先上调后下调的趋势,miR169 和miR398相对表达量也基本呈现出这一趋势。miR164、 miR167、 miR169和miR398的相对表达量在接菌12 h时上调至最高点,分别为对照的4.13、 2.84、 2.46和3.99倍; miR827相对表达量在接菌24 h时达到最高点,为对照的2.17倍。miR399相对表达量呈现出先下调后上调的趋势,在接菌24 h时降至最低点,为对照的0~21倍。3）通过靶基因预测,6条miRNA的靶基因分别编码了NAC1转录因子、 生长素响应因子、 HAP转录因子、 Cu/Zn 超氧化物歧化酶、 蛋白缀合酶PHO2和SPX-MFS亚家族蛋白。【结论】GFP-A.caulinodans能够从根毛和根尖破损处等部位进入小麦幼苗根部定殖,并可通过向上迁移到达叶片,在气孔处定殖。接种A.caulinodans可不同程度增加小麦根中响应氮素、 磷素、 微量元素的miRNAs相对表达量,增强小麦幼苗对营养元素的吸收和利用,促进小麦根的形态建成。