对北京地区建立自然保护区的意见

一、北京地区建立自然保护区的必要性北京位于华北大平原的西北部,正当太行山脉与燕山山脉的连接处,西北面是内蒙古高原和黄土高原,西、北、东三面环山,山地约占三分之二,一般高度在500—1,000米,个别山峰高达2,000米以上。属于温带大陆性季风气候,地带性植被为暖温带落叶阔叶林和松林。这一带是人类发祥地之一。长期的人为活动已使原始的自然景观变得面目皆非,仅在人烟稀少的偏僻山区才有原始景观的残迹,而大部分地区是遭多次破坏和改造过的次生植被。     

Impacts of organic and inorganic fertilizers on nitrification in a cold climate soil are linked to the bacterial ammonia oxidizer community

The microbiology underpinning soil nitrogen cycling in northeast China remains poorly understood. These agricultural systems are typified by widely contrasting temperature, ranging from −40 to 38°C. In a long-term site in this region, the impacts of mineral and organic fertilizer amendments on potential nitrification rate (PNR) were determined. PNR was found to be suppressed by long-term mineral fertilizer treatment but enhanced by manure treatment. The abundance and structure of ammonia-oxidizing bacterial (AOB) and archaeal (AOA) communities were assessed using quantitative polymerase chain reaction and denaturing gradient gel electrophoresis techniques. The abundance of AOA was reduced by all fertilizer treatments, while the opposite response was measured for AOB, leading to a six- to 60-fold reduction in AOA/AOB ratio. The community structure of AOA exhibited little variation across fertilization treatments, whereas the structure of the AOB community was highly responsive. PNR was correlated with community structure of AOB rather than that of AOA. Variation in the community structure of AOB was linked to soil pH, total carbon, and nitrogen contents induced by different long-term fertilization regimes. The results suggest that manure amendment establishes conditions which select for an AOB community type which recovers mineral fertilizer-suppressed soil nitrification.     

Sarcocystis cruzi: comparative studies confirm natural infections of buffaloes

Controversy exists concerning whether cattle and water buffalo sustain infections with cysts of distinct arrays of species in the genus Sarcocystis. In particular, morphologically similar parasites have been alternately ascribed to Sarcocystis cruzi or to Sarcocystis levinei, depending on their occurrence in cattle or water buffalo. We used light and transmission electron microscopy, genetic analysis, and experimental infections of definitive canine hosts to determine whether consistent differences could be identified from parasites derived from several natural infections of each host, examining several tissue types (esophagus, skeletal muscles, and heart). Cysts derived from cattle and water buffalo shared similar structure; variation among 18S rRNA sequences did not segregate consistently according to intermediate host type; parasites derived from cattle and water buffalo induced similar outcomes in the canine definitive host. One cattle specimen harbored unusually large (macroscopic) sarcocysts which nonetheless conformed to previously reported ultrastructural and genetic features of S. cruzi. Finding no consistent basis to differentiate between them, we conclude that the parasites infecting each host and tissue type correspond to S. cruzi. In our sample, no phylogenetically distinct taxon was sampled which might correspond to a distinct taxon previously described as S. levinei. Either that taxon was missed by our sampling effort, or it may represent a junior synonym to S. cruzi, which would then cycle between dogs and a broader range of intermediate bovine hosts than was previously considered.     

Presenilin-1 forms complexes with the cadherin/catenin cell-cell adhesion system and is recruited to intercellular and synaptic contacts

In MDCK cells, presenilin-1 (PS1) accumulates at intercellular contacts where it colocalizes with components of the cadherin-based adherens junctions. PS1 fragments form complexes with E-cadherin, beta-catenin, and alpha-catenin, all components of adherens junctions. In confluent MDCK cells, PS1 forms complexes with cell surface E-cadherin; disruption of Ca(2+)-dependent cell-cell contacts reduces surface PS1 and the levels of PS1-E-cadherin complexes. PS1 overexpression in human kidney cells enhances cell-cell adhesion. Together, these data show that PS1 incorporates into the cadherin/catenin adhesion system and regulates cell-cell adhesion. PS1 concentrates at intercellular contacts in epithelial tissue; in brain, it forms complexes with both E- and N-cadherin and concentrates at synaptic adhesions. That PS1 is a constituent of the cadherin/catenin complex makes that complex a potential target for PS1 FAD mutations.     

High production of laccase by a new basidiomycete, <Emphasis Type="Italic">Trametes</Emphasis> sp

A new basidiomycete, Trametes sp. 420, produced laccase at 6,810 U l⁻¹ (268 mg, 25.4 U mg⁻¹ protein for guaiacol) in glucose medium and 7,870 U l⁻¹ (310 mg) in cellobiose medium with induction by 0.5 mM Cu²⁺ and 6 mM o-toluidine. Laccase isozyme E (LacE) was the sole laccase in the fermentation products. It was stable at pH 5–9 and below 70°C over 30 min. The K _m values of LacE for four substrates (guaiacol ABTS, 2,6-dimethoxyphenol and syringaldazine) varied from 5 to 245 μM. The activity of LacE was strongly inhibited by NaN₃ but not by EDTA or dimethylsulfoxide. LacE at 0.5 U l⁻¹ could decolorize industrial dyes. The open reading frame of the lacE gene was 2,130 bp and was interrupted by 10 introns. It displayed a high homology to laccases from other fungi. Pingui Tong and Yuzhi Hong contributed equally to the study     

Production of xylanase from a newly isolated <Emphasis Type="Italic">Penicillium</Emphasis> sp. ZH-30

A new strain of Penicillium sp. ZH-30 that produces xylanase was isolated from soil. According to the morphology and comparison of internal transcribed spacer (ITS) rDNA gene sequence, the strain Penicillium sp. ZH-30 was identified as a strain of Penicillium oxalicum. When xylan or wheat bran was used as substrate at 30°C for 3 days under submerged cultivation, xylanase production was 5.3 and 13.3 U ml⁻¹, respectively. The temperature and pH for optimum activity were 50°C and 5.0–6.0, respectively.     

Bt rice expressing Cry1Ab does not stimulate an outbreak of its non-target herbivore, Nilaparvata lugens

In this study, the non-target effects of Bt rice “KMD2” expressing a Cry1Ab protein on the performance of the brown planthopper (BPH), Nilaparvata lugens, over multiple generations were evaluated under laboratory and field conditions. In the laboratory, BPH was reared to observe the impact of the Bt rice as compared to its parental non-Bt cultivar Xiushui 11, while the population dynamics and oviposition performance of BPH were investigated in the field. The survival of BPH nymphs fed Bt and non-Bt rice did not differ significantly. The nymph developmental duration of BPH was significantly delayed by the Bt rice by comparison with the non-Bt rice for the 1st and 2nd but not the 4th generation. Most importantly, the fecundity of BPH on the Bt rice was significantly decreased in every generation when compared with the non-Bt rice. In the field investigations, the population density of BPH nymphs was significantly lower in the Bt rice field. However, the temporal pattern of population dynamics of BPH adults was similar between the Bt and non-Bt rice, presumably due to migratory interference of the adults. In the Bt rice field, the percentage of tillers with eggs and the number of eggs per tiller were also significantly lower from tillering to mature stage. Additionally, Cry1Ab protein could not be detected in guts from single BPH adults. In general, our results suggest that the Bt rice “KMD2” could not stimulate an outbreak of BPH.     

一株撕裂蜡孔菌的分离培养及其系统发育分析

目的:分离出一株撕裂蜡孔菌(Ceriporia lacerata),通过PDAY培养基培养后,进行了培养特性及系统发育分析.方法:PDAY培养基培养菌丝体,电镜扣描获得菌丝微观形态,利用分子生物学方法对其rRNA基因内转录间区(ITS区)进行了克隆测序,与Genbank中已有的有关序列进行比较.结果:其ITS区与撕裂蜡孔菌同源率为98.8%～100%,属于一单独分支中,与白囊耙齿菌(Irpex lacteus)、射脉菌(Phlebia albida)及齿白木层孔菌(Leucophellinus irpicoides)的同源率为83.7%、81.2%及83.5%.结论:形态结果及分子鉴定表明撕裂蜡孔菌(Ceriporia lacerata)培养成功,菌丝体的获得为进一步开发利用提供了依据.