Catalytic and interfacial aspects of enzymatic polymer synthesis in reversed micellar systems

The enzyme horseradish peroxidase, when encapsulated in reversed micelles, is capable of catalyzing the synthesis of phenolic and aromatic amine polymers. The synthesis of polyethylphenol is specifically considered in this article and is found to be extremely feasible in the micellar system. Polymer chain growth can be controlled to some degree by manipulating the ability of the solvent to sustain chain solubility; this is effectively done by adjusting the surfactant concentration. This results in a degree of control of polymer molecular weight. The synthesized polymer drops out of solution and can be easily recovered. (c) 1993 John Wiley & Sons, Inc.     

Metabolic engineering of Clostridium acetobutylicum ATCC 824 for increased solvent production by enhancement of acetone formation enzyme activities using a synthetic acetone operon

The ability to genetically alter the product-formation capabilities of Clostridium acetobutylicum is necessary for continued progress toward industrial production of the solvents butanol and acetone by fermentation. Batch fermentations at pH 4.5, 5.5, or 6.5 were conducted using C. acetobutylicum ATCC 824 (pFNK6). Plasmid pFNK6 contains a synthetic operon (the "ace operon") in which the three homologous acetone-formation genas (adc, ctfA, and ctfB) are transcribed from the adc promoter. The corresponding enzymes (acetoacetate decarboxylase and CoA-transferase) were best expressed in pH 4.5 fermentations. However, the highest levels of solvents were attained at pH 5.5. Relative to the plasmid-free control strain at pH 5.5, ATCC 824 (pFNK6) produced 95%, 37%, and 90% higher final concentrations of acetone, butanol, and ethanol, respectively; a 50% higher yield (g/g) of solvents on glucose; and a 22-fold lower mass of residual carboxylic acids. At all pH values, the acetone-formation enzymes were expressed earlier with ATCC 824 (pFNK6) than in control fermentations, leading to earlier induction of acetone formation. Furthermore, strain ATCC 824 (pFNK6) produced butanol significantly earlier in the fermentation and produced significant levels of solvents at pH 6.5. Only trace levels of solvents were produced by strain ATCC 824 at pH 6.5. Compared with ATCC 824, a plasmid-control strain containing a vector without the ace operon also produced higher levels of solvents [although lower than those of strain ATCC 824 (pFNK6)] and lower levels of acids. Strains containing plasmid-borne derivatives of the ace operon, in which either the acetoacetate decarboxylase or CoA-transferase alone were expressed at elevated levels, produced acids and solvents at levels similar to those of the plasmid-control strain. (c) 1993 John Wiley & Sons, Inc.     

Host selection and survival of the parasitoidEncarsia formosa on greenhouse whitefly,Trialeurodes vaporariorum, in the presence of hosts infected with the fungusAschersonia aleyrodis

Successful control of greenhouse whitefly may be achieved by complementary activity of the parasitoidEncarsia formosa and the fungusAschersonia aleyrodis. One way to obtain an additive mortality effect of both entomopathogen and parasitoid would be achieved by the selection of healthy hosts by the parasitoid and rejection of fungus-infected hosts. Third and fourth instar larvae ofTrialeurodes vaporariorum which had been treated with a spore suspension ofA. aleyrodis 0, 4, 7, 10 or 14 days beforehand, were presented to female parasitoids. The parasitoids adopted the oviposition posture on untreated hosts as well as on treated hosts, irrespective of the different stages of infection in the hosts. However, significantly more hosts were parasitized byE. formosa in the control treatment than in the fungal treatment. The parasitoids offered treated hosts, showed rejection behaviour after probing on hosts showing detectable signs of infection (containing hyphal bodies or mycelium in the haemolymph). For instance, when hosts were offered seven days after spore treatment, the parasitoids showed an oviposition posture on a total of 83 (95.4%) out of 87 infected larvae, but laid only 4 eggs (4.6%). In contrast, on 48 (94.1%) out of 51 noninfected (or showing no detectable signs of infection) hosts an oviposition posture was adopted and 40 eggs (78.4%) were found after dissection. When infected hosts were encountered the oviposition posture lasted less than 1′40″ while rejection of non-infected hosts occurred after more than 1′40″. Other experiments were carried out offering treated hosts for 24 h to the parasitoids. The hosts were dissected afterwards. Again, significantly more eggs were laid in the non-infected hosts. When hosts were parasitized shortly after fungal spore treatment they were colonized by the fungus and the parasitoids did not develop. Transmission of the entomopathogen after probing infected hosts was observed to a limited extent. In conclusion,A. aleyrodis andE. formosa can be used together in a glasshouse situation. The parasitoid will be most effective when introduced more than seven days after application ofA. aleyrodis, because from that time onwards it is able to detect and reject fungus-infected hosts.     

Source of an egg kairomone for Trissolcus basalis, a parasitoid of Nezara viridula

Abstract. The eggs of the southern green stink bug, Nezara viridula (L.) (Hemiptera: Pentatomidae), are successfully attacked by Trissolcus basalis (Woll.) (Hymenoptera: Scelionidae) and are recognized as hosts by a secretion applied to the egg chorion. This secretion is produced by the follicular cells in the proximal region of the ovariole of the female pentatomid and functions as an adhesive for attaching the eggs to the oviposition substrate. The adhesive and kairomone activity could be partially removed with water. This water extract elicited host recognition behaviour in T. basalis when applied to glass beads which stuck together as the extract dried. The adhesive and kairomonal activity was removed completely with acetone since acetone-washed host eggs were not recognized by T. basalis. Application of the acetone extract to glass beads stimulated ovipositional probes by T. basalis. The adhesive appeared to be composed of a mucopolysaccharide–protein complex.     

江苏海岸带陆生盐土植物矿质元素含量的特点及生物循环

陆生盐土植物在生长过程中吸收积累了大量的Cl和Na;从海向陆随着土壤和植被的生态演替,植物中Cl和Na的浓度逐渐降低;N与Cl、Na有相似的水平分布规律;植物种类是影响元素吸收积累的主要因素。在盐地碱蓬中N、P、K、Ca、Mg、Na、Cl、Mn和Zn的含量均是生长前期较高,随着其生长老化逐渐降低,大穗结缕草、白茅与盐地碱蓬相比,Ca的含量前期低后期高,Na、Mn、Cu和Zn的季节变化不明显。参加盐地碱蓬系统生物循环的元素中,Cl和Na的比例最大,在大穗结缕草和白茅生态系统中比例较小;由于白茅被收割利用,一些元素从此生态系统中流失。     

桑白蚧的重要寄生蜂——桑白蚧恩蚜小蜂的鉴别与利用

桑白蚧恩蚜小蜂Encarsia(=Prospaltella)berlesel(Howard)是寄生桑白蚧Pseudaulacaspls pentagona(Targioni-Tozzctti)的重要寄生蜂,许多国家进行了引进移植,对控制桑白蚧的为害取得明显的成效．本记述了桑白蚧恩蚜小蜂形态特征的鉴别。以及各国引进利用的概况．并讨论了利用寄生蜂防治桑白蚧的重要性．     

A trait-based approach to assess niche overlap and functional distinctiveness between non-indigenous and native species

Our understanding of the community assembly processes acting on non-indigenous species (NIS), as well as the relationship with native species is limited, especially in marine ecosystems. To overcome this knowledge gap we here develop a trait-based approach based on the functional distinctiveness metric to assess niche overlap between NIS and native species, using high-resolution data on benthic invertebrate communities in the Baltic Sea. Our results show that NIS retain a certain degree of similarity with native species, but display one or a few singular unique traits (e.g., bioturbation ability). Furthermore, we demonstrate that community assembly processes, including both environmental filtering and limiting similarity affect NIS establishment, but that their effects may be highly context dependent, as illustrated by pronounced spatial patterns in distinctiveness. Finally, our trait-based approach provides a generic framework applicable to other areas and organisms, to better understand and address biological invasions.     

厌氧氨氧化菌驱动脱氮途径的研究进展

厌氧氨氧化菌(anaerobic ammonia-oxidizing bacteria, AnAOB)的代谢多样性,使得该菌群能够在海洋、湿地和陆地等不同的自然生态系统中广泛分布,甚至在一些极热和极寒环境中也检测到了该菌群的存在。本文回顾并总结了厌氧氨氧化菌在不同生态系统中的发现、分布及脱氮贡献等方面的研究,分析了厌氧氨氧化菌分布的主要环境影响因素。该综述将帮助我们更好地理解全球氮循环中厌氧氨氧化菌的实际角色和功能,并基于厌氧氨氧化(anaerobicammoniaoxidation,anammox)过程,探究能与其进行协作的新型生物脱氮工艺,以期为这些工艺的研发和推广提供生态学基础和新的思考,从而实现脱氮工艺的技术变革。     

Biological samples taken from Native American Ancestors are human remains under NAGPRA

In the United States, the Native American Graves Protection and Repatriation Act (NAGPRA) provides a specific framework for the disposition of Native American Ancestral remains within its purview. However, samples such as a bone fragment, tooth, or other biological tissue taken from the remains of these Ancestors have been treated by institutions and researchers as independent of the individual from whom they were removed and used in destructive research such as paleogenomic and other archaeometric analyses without consultation, consent, and collaboration from Native American communities; are not cared for in keeping with the current best practices for Indigenous Ancestors; and are not likely to be repatriated to their communities. Here, we demonstrate that any biological samples removed from Ancestors who are covered under NAGPRA must also be handled according to the stipulations defined for “human remains” within the legislation. As such, we are not proposing a change to existing legislation, but rather best practices, specific to the context of the United States and NAGPRA, relating to the use of and care for biological samples taken from Native American Ancestors.