太湖地区湿沉降中氮磷输入量 ——以常熟生态站为例

2003年6月—2004年5月,在中国科学院常熟生态站(31°32′45″ N ,120°41′57″ E)连续定位收集降雨,分析其中颗粒态和溶解态氮磷浓度,并对期间太湖地区氮磷湿沉降动态进行研究.结果表明：湿沉降氮输入量的季节变化显著,夏、春季高,秋、冬季低;湿沉降输入氮中88.2%为溶解氮（dissolved itrogen,DN）,11.8%为颗粒氮（particle nitrogen,PN）;湿沉降输入磷中溶解磷（dissolved phosphorus,DP）和颗粒磷（particle phosphorus,PP）比例分别为53.3%和46.7%;中、小雨携带的总氮（total nitrogen,TN）、总磷（total phosphorus,TP）污染物通量大于大、暴雨;太湖地区每年湿沉降输入TN、TP分别为30.2 kg·hm^-2和1.1 kg·hm^-2,且所有降雨中DN浓度均大于水体富营养化阈值,92.5%的降雨中DP大于水体富营养化阈值.     

Contribution of gut bacteria to digestion and development of the velvetbean caterpillar, Anticarsia gemmatalis

Bacteria colonies from gut homogenates of fifth instar velvetbean caterpillars (Lepidoptera: Noctuidae) were subjected to antibiotic sensitivity experiments using discs containing 22 antibiotics. The antibiotic tetracycline provided the best results, followed by chloramphenicol. Tetracycline also provided higher inhibition of colony forming units than chloramphenicol and was therefore provided to the caterpillars in increasing diet concentrations to assess the contribution of gut bacteria to their digestion and development. The activity of proteases (general), serine-proteinases and lipases were significantly suppressed by tetracycline. Concentration-inhibition curves were successfully established for tetracycline and this antibiotic was effective in suppressing them, particularly serine-proteinases, suggesting that gut bacteria may significantly contribute with lipid- and mainly protein-digestion in velvetbean caterpillars. Increased diet concentrations of tetracycline led only to mild increase in insect mortality (ca. 20%), with the surviving insects showing faster development (≤4 days) and higher pupa weight (<0.04 mg) with increased concentrations of tetracycline. Therefore, the gut bacteria inhibited by tetracycline does not seem to play a crucial role in the survival and development of the velvetbean caterpillar, but may be important in the adaptation of this pest species to hosts rich in protease inhibitors, such as soybean.     

Characterization of Bacillus subtilis spore inactivation in low‐pressure,low‐temperature gas plasma sterilization processes

Aims: To identify structural components of Bacillus subtilis spores serving as targets for sterilization with microwave induced low‐pressure, low‐temperature nitrogen‐oxygen plasma. Methods and Results: The inactivation of spores followed a biphasic kinetics consisting of a log‐linear phase with rapid inactivation followed by a slow inactivation phase. In the course of plasma treatment, damage to DNA, proteins and spore membranes were observed by monitoring the occurrence of auxotrophic mutants, inactivation of catalase (KatX) activity and the leakage of dipicolinic acid, respectively. Spores of the wild‐type strain showed the highest resistance to plasma treatment. Spores of mutants defective in nucleotide excision repair (uvrA) and small acid‐soluble proteins (ΔsspA ΔsspB) were more sensitive than those defective in the coat protein CotE or spore photoproduct repair (splB). Exclusion of reactive particles and spectral fractions of UV radiation from access to the spores revealed that UV‐C radiation is the most effective inactivation agent in the plasma, whereby the splB and ΔcotE mutant spores were equally and slightly less sensitive, respectively, than the wild‐type spores. Finally, the extent of damages in the spore DNA determined by quantitative PCR correlated with the spore inactivation. Conclusions: Spore inactivation was efficiently mediated by a combination of DNA damage and protein inactivation. DNA was identified to be the primary target for spore inactivation by UV radiation emitted by the plasma. Coat proteins were found to constitute a protective layer against the action of the plasma. Significance and Impact of the Study: The results provide new evidence to the understanding of plasma sterilization processes. This knowledge supports the identification of useful parameters for novel plasma sterilization equipment to control process safety.     

电场刺激技术在微生物工程中的应用

电场刺激是利用电解法将惰性电极插入电解液中,形成一种电解池系统,电解液对细胞培养物会产生不同影响,并导致生物过程发生改变。电场刺激对微生物会产生促进和杀灭两种不同作用,并在微生物工程中已有所应用,如促进微生物生长和代谢、强化废水处理、进行生物修复和用于杀菌消毒等。研究表明电场刺激在微生物工程和环境生物工程等方面有广泛的应用前景。     

Fine partitioning of epiphyte habitat within Johansson zones in tropical Australian rain forest trees

For over three decades, the Johansson zones have been widely used in epiphyte studies as a way of stratifying the host tree into habitat zones. The usefulness of this system, however, has been questioned. We test the effectiveness of the Johansson zones by grouping epiphyte species by the substrate and microclimatic attributes of their individual occurrences and assessing the fidelity of these groups to the Johansson zones. Habitat characteristics were recorded for every individual epiphyte on 30 trees in the lower montane rain forests of northeastern Australia. Twenty‐four epiphyte species were agglomerated into four groups using Ward's method. Group 4 was highly distinct and included shade‐loving species and nomadic vines from the lower zones of the host trees. Group 3 contained species from the most exposed habitats. Group 1 had higher light levels and lower substrate thickness than Group 2, yet both groups had close to identical distributions over the Johansson zones. This suggests that groups of epiphyte species may utilize different micro‐sites within the same zone. While the Johansson zones are a useful tool in epiphyte studies, finer partitioning of habitat within the host tree may be missed.     

土壤呼吸对降雨响应的研究进展

土壤呼吸是当前区域碳收支及全球变化研究中的一个热点问题。降雨作为一个重要的扰动因子, 对准确估算土壤呼吸具有重要影响, 这在干旱和半干旱地区尤为明显。尽管关于土壤呼吸对降雨响应过程与规律的研究已取得了较大进展, 但是对于其机制的解释仍然存在较大的争议, 集中体现在对“Birch效应” (降雨强烈激发土壤呼吸的现象)的解释上, 即到底是“底物供应改变机制”还是“微生物胁迫机制”在调控该过程。该文综述了土壤呼吸对降雨事件、降雨量及降雨格局的响应过程与规律; 阐述了土壤呼吸各组分对降雨响应的差异, 分析了雨后物理替代与阻滞、底物供应、根系和微生物活性、微生物群落结构与功能等一系列过程引起土壤呼吸改变的机制; 重点阐述了微生物对土壤水分波动的响应与适应机制。在此基础上提出了今后需重点关注的4个方面：1) “底物供应改变机制”与“微生物胁迫机制”的区分; 2)土壤呼吸各组分对降雨响应的差异; 3)不同时空尺度上土壤呼吸对降雨响应的模拟与估算; 4)降雨带来的外援N和H⁺的作用。     

The lipidome and proteome of microsomes from the methylotrophic yeast Pichia pastoris

The methylotrophic yeast Pichia pastoris is a popular yeast expression system for the production of heterologous proteins in biotechnology. Interestingly, cell organelles which play an important role in this process have so far been insufficiently investigated. For this reason, we started a systematic approach to isolate and characterize organelles from P. pastoris. In this study, we present a procedure to isolate microsomal membranes at high purity. These samples represent endoplasmic reticulum (ER) fractions which were subjected to molecular analysis of lipids and proteins. Organelle lipidomics included a detailed analysis of glycerophospholipids, fatty acids, sterols and sphingolipids. The microsomal proteome analyzed by mass spectrometry identified typical proteins of the ER known from other cell types, especially Saccharomyces cerevisiae, but also a number of unassigned gene products. The lipidome and proteome analysis of P. pastoris microsomes are prerequisite for a better understanding of functions of this organelle and for modifying this compartment for biotechnological applications.     

广州城市绿地系统景观异质性分析

选用景观多样性等7个指数对广州城市绿地景观异性质进行了分析.结果表明,广州绿地斑块密度和绿廓道密度分别为11.8和1.87km·km^-2,在老城区绿地具有斑块小,破碎度大,多样性高,以随机分布为主的高异质性空间结构;在新城区,绿地斑块大,以均匀分布为主,因此,在同等大小的区域内,这类绿地空间结构更能提高景观的异质性,更有效地发挥绿地的生态功能.     

Diversity of insect‐induced galls along a temperature– rainfall gradient in the tropical savannah region of the Northern Territory,Australia

Evidence regarding the effect of temperature and rainfall on gall‐inducing insects is contradictory: some studies indicate that species richness of gall‐inducing insects increases as environments become hotter and drier, while others suggest that these factors have no effect. The role of plant species richness in determining species richness of gall‐inducing insects is also controversial. These apparent inconsistencies may prove to be due to the influence of soil fertility and the uneven distribution of gall‐inducing insect species among plant taxa. The current study tested hypotheses about determinants of gall‐inducing insect species richness in a way different to previous studies. The number of gall‐inducing insect species, and the proportion of species with completely enclosed galls (more likely to give protection against heat stress and desiccation), were measured in replicate plots at five locations along a 500‐km N‐S transect in the seasonal tropics of the Northern Territory, Australia. There is a strong temperature–rainfall gradient along this transect during the wet season. Plant species lists had already been compiled for each collection plot. All plots were at low elevation in eucalypt savannah growing on infertile soils. There was no evidence to suggest that hot, dry environments in Australia have more gall‐inducing insect species than cooler, wetter environments, or that degree of enclosure of galls is related to protecting insects from heat stress and desiccation. The variable number of gall‐inducing insect species on galled plant species meant that plant species richness did not influence gall species richness. Confirmation is still required that low soil fertility does not mask temperature–rainfall effects and that galls in the study region are occupied predominantly in the wet season, when the temperature–rainfall gradient is most marked.