顶复门原虫与细菌Ⅱ型丙二酰单酰辅酶A:ACP转酰基酶研究进展

大部分顶复门原虫与人畜重要寄生虫病密切相关.近年来,由于各类药物在寄生虫与细菌病防治中的广泛应用,甚至是滥用,造成了这类寄生虫与细菌的严重抗药性,急需一些新型抗感染性药物的出现.由于在一些顶复门原虫与细菌中广泛存在的Ⅱ型脂肪酸代谢途径在其脊椎动物宿主中并不存在,而丙二酰单酰辅酶A∶ACP转酰基酶(malonyl-CoA...     

不同施氮量对饲用燕麦光合特性及氮素光合利用效率的影响

为探明不同施氮量下饲用燕麦在晋北地区光合特性及氮素光合利用效率的差异,以4个国内外具有代表性的饲用燕麦品种为试验材料,研究其生物产量、光合特性及氮素光合利用效率的变化特点。结果表明,4个参试品种的干草产量均随着施氮量的增加呈递增趋势,均在施氮量180kg/hm²时最高;随着施氮量的增加,各品种净光合速率和氮素光合利用效率呈持续增加的趋势。综合各项指标可知,晋北地区蒙燕1号、甜燕麦、KONA和坝燕7号4个燕麦品种生产时,田间施氮量可控制在180kg/hm²水平。     

Effect of agricultural land use change on community composition of bacteria and ammonia oxidizers

Purpose

Soil microbial communities can be strongly influenced by agricultural practices, but little is known about bacterial community successions as land use changes. The objective of this study was to determine microbial community shifts following major land use changes in order to improve our understanding of land use impacts on microbial community composition and functions.

Materials and methods

Four agricultural land use patterns were selected for the study, including old rice paddy fields (ORP), Magnolia nursery planting (MNP), short-term vegetable (STV), and long-term vegetable (LTV) cultivation. All four systems are located in the same region with same soil parent material (alluvium), and the MNP, STV, and LTV systems had been converted from ORP for 10, 3, and 30 years, respectively. Soil bacteria and ammonia oxidizer community compositions were analyzed by 454 pyrosequencing and terminal restriction fragment length polymorphism, respectively. Quantitative PCR was used to determine 16S rRNA and amoA gene copy numbers.

Results and discussion

The results showed that when land use was changed from rice paddy to upland systems, the relative abundance of Chloroflexi increased whereas Acidobacteria decreased significantly. While LTV induced significant shifts of bacterial composition, MNP had the highest relative abundance of genera GP1, GP2, and GP3, which were mainly related to the development of soil acidity. The community composition of ammonia-oxidizing bacteria (AOB) but not ammonia-oxidizing archaea was strongly impacted by the agricultural land use patterns, with LTV inducing the growth of a single super predominant AOB group. The land use changes also induced significant shifts in the abundance of 16S rRNA and bacterial amoA genes, but no significant differences in the abundance of archaea amoA was detected among the four land use patterns. Soil total phosphorous, available phosphorous, NO₃ ^?, and soil organic carbon contents and pH were the main determinants in driving the composition of both bacteria and AOB communities.

Conclusions

These results clearly show the significant impact of land use change on soil microbial community composition and abundance and this will have major implications on the microbial ecology and nutrient cycling in these systems, some of which is unknown. Further research should be directed to studying the impacts of these microbial community shifts on nutrient dynamics in these agroecosystems so that improved nutrient management systems can be developed.     

Fragmentation and recreational use affect tree regeneration in urban forests

The aim of this study was to test whether fragmentation or recreational use affect tree regeneration in urban forests, and to quantify these effects. We sampled tree saplings at different distances from edges in spruce (Picea abies) dominated forests, and at different distances from paths that represented different levels of wear. Generalized linear mixed models were used to test our hypotheses. We found that fragmentation favours the regeneration of deciduous trees in urban spruce dominated forests: distance from the edge had a pronounced effect on regeneration, at least up to 80 m into the forests. Saplings of Betula pendula, Populus tremula, other deciduous species and Pinus sylvestris benefited from edge conditions. Betula pubescens saplings, however, were most abundant in the interior and small Sorbus aucuparia saplings at 25–30 m from the edge. All species suffered from the direct effects of trampling, while varying responses of species to distance from the paths were observed up to 6 m, and possibly further. As trees essentially define the living conditions for other forest species, we suggest that the spatial extent of edge and trampling effects should be studied for different types of forests. This knowledge should then be used in urban forestry and planning to define the threshold value that will allow for at least some “intact” interior. We suggest a diameter larger than 160 m to support indigenous species in boreal spruce dominated forests.     

Distribution of bacteria and seasonal and regional effects in a new database for mastitis pathogens in Finland

Abstract

A database containing pathogen-specific information on mastitis has been established in Finland. The data consist of the results from routine milk samples collected from clinical and subclinical mastitis and submitted to laboratories all over the country. In the database, bacteriological information has been recorded on an individual cow basis. A total of 77,051 pathogen records submitted to the database from 1 January 2004 to 1 January 2006 were retrieved for this preliminary report of pathogen distribution. Staphylococcus aureus (18.26% and 17.73%) and coagulase negative staphylococci (CNS) (17.57% and 23.51%) were the most frequently isolated pathogens from the milk samples. Seasonal and regional differences in pathogen distribution were also found. The pathogen information is primarily used for targeting the antimicrobial treatment of the cow, but also for designing specific mastitis control strategies for the herds. Pathogen data can also be useful for national mastitis control programmes and breeding programmes of dairy cattle for the selection of more resistant animals.     

海洋红酵母RH1菌株发酵培养条件的研究

该研究比较了不同碳源、氮源、无机盐对海洋红酵母菌（Rhodotorula sp.）RH1菌株发酵产量的影响,通过葡萄糖、蛋白胨、酵母膏和硫酸镁（MgSO4）4因素3水平的正交试验,确定了RH1菌株的最优培养基为蛋白胨10 g.L-1,酵母膏15 g.L-1,葡萄糖20 g.L-1,MgSO40.25 g.L-1,磷酸二氢钾（KH2PO4）0.25 g.L-1,氯化钠（NaCl）10 g.L-1。结果显示,该菌株最佳摇瓶发酵条件为接种量10%,初始pH 5.0,摇瓶装液量80 mL/500 mL三角瓶,培养温度28℃,经48 h培养,菌量可达10.46×108cfu.mL-1,比优化条件前提高23.9%。还进行了RH1菌株25 L发酵罐扩大培养试验,在接种量为8%、初始pH 5.0、搅拌速率350～400 r.min-1、通气量9 L.min-1、温度28℃的条件下,经28 h的培养,菌量可达33.6×108cfu.mL-1。预计通过连续补料的方式进行培养,有望进一步提高菌量。     

The idea of ‘Country’: Reframing post‐disaster recovery in Indigenous Taiwan settings

In Australian Aboriginal thinking, the idea of ‘Country’ comprises complex ideas about relationships and connection. It simultaneously encompasses territorial affiliation, a social identification and cosmological orientation. It draws attention to what might be glossed as people‐to‐environment, people‐to‐people and people‐to‐cosmos relations. These relations influence disaster responses, but are rarely mobilised explicitly in shaping formal recovery and reconstruction efforts. Colonial disruption of connections to Country imposed new practices and presences into contemporary Indigenous geographies and is often reinforced in disaster settings. This paper considers more recent disruptions arising from post‐disaster recovery in Taiwan, arguing that the idea of Country offers a powerful way of framing cultural and social dimensions of post‐disaster relief and recovery for government agencies, non‐government organisations and research alike.     

贮藏温度对中国水仙鳞茎碳水化合物含量的影响

以中国水仙‘金盏银台’品种3年生休眠鳞茎为试验材料,研究在5、15、25、35℃和室温(CK)贮藏下鳞茎内鳞片、外鳞片和主芽的可溶性糖和淀粉含量的变化。结果表明:鳞茎内鳞片、外鳞片和主芽淀粉含量变化受贮藏温度的影响显著;不同贮藏温度下内鳞片、外鳞片和主芽的可溶性糖含量都基本稳定在一定的水平,而淀粉含量整体波动较大。在鳞茎贮藏期的叶芽和花芽分化期间,不同温度对淀粉水解产生显著影响,对可溶性糖的影响不显著,淀粉水解跟主芽的发育密切相关。因此,通过淀粉来研究了解水仙鳞茎贮藏期间碳水化合物的变化更适宜。      

顶复门原虫棒状体蛋白疫苗候选分子的研究进展

顶复门原虫是一类专一性的胞内寄生性原虫,其种类丰富、分布广泛,包括艾美耳球虫、巴贝斯虫、隐孢子虫、疟原虫和弓形虫等.此类原虫具有保守的棒状体、致密颗粒以及微线等顶端复合器结构,这些细胞器可分泌大量的入侵相关蛋白分子介导虫体入侵宿主细胞.而棒状体蛋白是这类原虫在入侵过程中由棒状体分泌的一类蛋白,其在虫体入侵宿主细胞、纳虫...     

寄生原虫DNA解旋酶家族研究进展

寄生原虫是一类单细胞真核生物,是人和动物疾病的重要病原之一,给人类健康和畜牧业发展造成了严重的危害。DNA解旋酶是一类参与几乎所有生物DNA代谢的重要解旋酶,目前原虫DNA解旋酶的研究主要集中在恶性疟原虫,且被报道的DNA解旋酶多为人类或酵母的同源物,其保守基序与人类、酵母等都存在差异,是研究抗原虫药物的重要潜在靶标。笔者主要综述了经典解旋酶的保守结构域及其功能特点,介绍了各个解旋酶的极性与偏好底物等生化特性,汇总了已报道原虫DNA解旋酶的种类。目前报道的DNA解旋酶大多集中在恶性疟原虫,其中疟原虫含18种,利士曼原虫含3种,布氏锥虫和兔脑原虫均含2种,弓形虫含1种。同时介绍了目前原虫中较为引人关注DNA解旋酶：RecQ家族、DEAD-box家族、UvrD解旋酶家族和RuvB家族的功能研究进展,其中DEAD-box家族中有3种疟原虫特异性解旋酶PfPSH1/H2/H3并未在宿主人类中发现相似物,另一种解旋酶UvrD则与人类、小鼠、秀丽隐杆线虫等无同源性,而与细菌、真菌等同源性较高。笔者对原虫DNA解旋酶的基本特性和功能进行综述,阐述了目前原虫DNA解旋酶的研究进展及其作为药物靶标的可能...