有机磷农药对土壤动物群落结构的影响研究

本文研究了有机磷农药废水灌溉对土壤动物群落结构的影响,并探讨了影响机理,结果表明,土壤动物种类和数量随着农药影响程度的增加而减少,在农药污染影响严重的１、２区,计有土壤动物２１类和２２类,动物平均密度为２８５７１个／ｍ＾２和５１２６９个／ｍ＾２,受中度和轻蔗污染影响的３、４区分别有３５类和４７类,平均密度为５９２８５个／ｍ＾２,１５６５８７个／ｍ＾２。污染区土壤动物种类的减少主要由于常见类群和稀有     

Gathering and processing of lyme-grass (Elymus arenarius L.) in Iceland: an ethnohistorical account

Lyme-grass (Elymus arenarius L.) was harvested and processed for human consumption along the southern coast of Iceland until the beginning of this century. The origin of this exploitation is not known, but lyme-grass may have been gathered for this purpose already in the Viking Age. The system of processing lyme-grass is complex, and special implements and facilities are needed. The method is similar to traditional processing methods for cereals. Extensive research on Icelandic ethnographic observations was undertaken to establish the exact methods and sequence of operations that was involved. On the basis of this, a set of archaeological experiments was performed to test the viability of the processing techniques outlined in the written records. A model describing the harvesting and processing of lyme-grass is presented.     

动物细胞在鼓泡式生物反应器中的死亡速率

通过实验测定,证明生物反应器中细胞死亡速率与气体鼓泡速率成正比而与反应器体积成反比。实验发现气泡大小对细胞死亡速率具有两种作用,一种作用在于影响气泡表面积生成速率;另一种作用则在于影响细胞在气泡表面的吸附程度,其最佳直径为5mm左右。血清和Pluronic F68能显著降低细胞死亡速率,当Pluronic F68浓度达到0．1％时,kd趋于零。所有这些实验结果均与前文提出的生物反应器设计模型具有很好的一致性。     

一种模拟高原低氧复合冷冻的简易动物实验舱

以氮稀释法使舱内氧含量维持实验模拟高度,以普通冰箱制冷系统维持舱内恒温,以多功能低温浴槽作为致冻装置。该舱可于２０ｍｉｎ内升至模拟６０００ｍ高度,每次可供１６只大鼠作高原冻伤实验。实验期间高度恒定于６０００±２００ｍ,舱温２１±１℃。相对湿度５５％±１５％,冷冻液－２５．０±０．５℃。该舱结构简单、使用方便,可在实验室中模拟高原条件进行冷冻实验研究。由于不使用人体减压舱,不仅避免了减压缺氧对实验人员的不利影响,也减少了实验消耗。     

Vegetation establishment on chalk marl spoil: the role of nurse grass species and fertiliser application

Abstract. The Channel Tunnel workings on the UK side have yielded nearly 4 million m³ of chalk-marl spoil which now forms a 36 ha landscaped reclamation platform. To establish vegetation of amenity and conservation interest on the spoil, seed mixtures of native wild flowers and grasses were sown with Lolium perenne (perennial rye grass) as a nurse species. Potentially, L. perenne is a suitable nurse species for grassland creation on infertile substrates as it provides rapid initial cover and stability, but it is non-persistent and declines in vigour with time, allowing wild flower species sown alongside to expand their cover and spread in the longer term. On very low fertility substrates like chalk marl, an initial application of fertilizer is needed to encourage plant growth. Results are reported of a fertilizer experiment on Channel Tunnel spoil to determine appropriate levels of fertilizer for establishment of species-rich grassland vegetation. An area hydroseeded with L. perenne and wild flowers in autumn 1992 was subjected to factorial treatment of four levels each of N and P in spring 1993. The results the following summer showed significant positive effects of nitrogen and phosphorus on L. perenne biomass and a negative impact of nitrogen on densities of wild flower species, especially legumes, establishing in the L. perenne sward. In general, low fertilizer applications encouraged low productivity and maximal species richness in the vegetation. Conversely high applications encouraged high productivity and competitive exclusion of sown wild flower species. Fertilizer applications must therefore balance encouragement of the stabilising nurse grass sward, while preventing competitive exclusion of wild flowers by the nurse grass.     

Simulation and dynamic optimisation of animal cell culture

In animal cell culture, there are some 25 substrates that both have a significant effect on the culture performance and which can be measured with relative ease. A detailed dynamic simulation for such a culture has been produced and an optimisation policy that use this model to identify ideal media conditions has been developed. This paper describes an extension of that work to include the dynamic optimisation of cultures under fed-batch operation. Two different types of feeding policy were considered – in the first, discrete shots of feed were supplied, while in the second, feed was added continuously. Both policies offered significant improvements in the predicted productivity of the culture - up to 30% that of an experimentally optimisedbatch culture.     

The Human Obesity Gene Map: The 1996 Update

An update of the human obesity gene map up to October 1996 is presented. Evidence from Mendelian disorders exhibiting obesity as a clinical feature, single-gene mutation rodent models, quantitative trait loci uncovered in crossbreeding experiments with mouse, rat, and pig models, association and case-control studies with candidate genes, and linkage studies with genes and other markers is reviewed. All chromosomal locations of the animal loci are converted into human genome locations based on syntenic relationships between the genomes. A complete listing of all these loci reveals that only 4 of the 24 human chromosomes are not yet represented, i.e., 9, 18, 21, and Y. Several chromosome arms are characterized by the presence of several putative loci. The following arms include at least three such loci: 1p, 1q, 3p, 4q, 6p, 7q, 8p, 8q, 11p, 11q, 15q, 20q, and Xq. Studies with negative association and linkage results are also reviewed.     

Brief overview of control of genetic expression by antisense oligonucleotides and in vivo applications

Over the past several years, the use of synthetic oligonucleotides and functional analogs thereof as a possibly general means of controlling genetic expression has received widespread attention. Following a brief overview of some of the basic principles and strategies for this approach, attention is focused here on summarizing some recent reports of in vitro and, in particular, in vivo investigations in various animal models using phosphorothioate analogs of 2′-deoxyoligo-nucleotides. In view of these findings, which include studies related to neurobiology, this field should find significant utility in applications of the antisense method for controlling genetic expression.     

Bioprocessing in space: Human cells attach to beads in microgravity

Attachment to a substrate and survival of human embryonic kidney (HEK) cells have been tested in an incubator installed in the flight-deck of the Space Shuttle ‘Challenger’ during its eighth mission.HEK cells are producing the enzyme urokinase and are presently investigated as candidates for electrophoretic separation in an apparatus developed and manufactured by McDonnell Douglas.Attachment of HEK cells to a substrate is mandatory for survival and production of urokinase after electrophoretic separation.Analysis of the samples shows that cells adhere, spread and survive in microgravity (< 10⁻³ ×g) conditions as well as the ground controls at 1 × g. This result represents an important step towards further bioprocessing in space.