Degradation and induction specificity in actinomycetes that degrade p-nitrophenol.

We have isolated two soil bacteria (identified as Arthrobacter aurescens TW17 and Nocardia sp. strain TW2) capable of degrading p-nitrophenol (PNP) and numerous other phenolic compounds. A. aurescens TW17 contains a large plasmid which correlated with the PNP degradation phenotype. Degradation of PNP by A. aurescens TW17 was induced by preexposure to PNP, 4-nitrocatechol, 3-methyl-4-nitrophenol, or m-nitrophenol, whereas PNP degradation by Nocardia sp. strain TW2 was induced by PNP, 4-nitrocatechol, phenol, p-cresol, or m-nitrophenol. A. aurescens TW17 initially degraded PNP to hydroquinone and nitrite. Nocardia sp. strain TW2 initially converted PNP to hydroquinone or 4-nitrocatechol, depending upon the inducing compound.     

Distribution and functional significance of Met-enkephalin-Arg6-Phe7- and Met-enkephalin-Arg6-Gly7-Leu8-like peptides in the blowfly Calliphora vomitoria

Summary Neuronal pathways immunoreactive to antisera against the extended-enkephalins, Met-enkephalin-Arg⁶-Phe⁷ (Met-7) and Met-enkephalin-Arg⁶-Gly⁷-Leu⁸ (Met-8), have been identified in the brain of the blowfly Calliphora vomitoria. Co-localisation with other enkephalins in certain neurons suggests that a precursor similar to preproenkephalin A exists in insects and that differential enzymatic processing occurs as in vertebrates. Co-localisations of the extended-enkephalin-like peptides with other vertebrate-type peptides, including cholecystokinin and pancreatic polypeptide, also occur. The enkephalinergic pathways are specific, comprising a few groups of highly characteristic neurons and areas of neuropil. Of special interest is the finding that parts of the antennal chemosensory and the optic lobe visual systems contain Met-8 immunoreactive neurons. Within the median neurosecretory cell groups, some of the giant neurons show immunoreactivity to Met-8 and others to both Met-8 and Met-7. Fibres from these cells project to the corpus cardiacum and also to the suboesophageal ganglion, where arborisations occur in the tritocerebral neuropil. Co-localisation studies of these cells have shown that at certain terminals, one particular type of peptide is the dominant neuroregulator, whilst at other terminals, within the same cell, a different co-synthesised peptide predominates. Several groups of lateral neurosecretory cells show clearly defined enkephalinergic pathways, most of which have connections with the central body. The complex patterns of immunoreactivity seen in terminals in the different parts of the central body, suggest an important role for the enkephalin-like peptides in the integration of multimodal sensory inputs. The physiological functions of the extended-enkephalin-like peptides in the brain of Calliphora is still unknown, but the anatomical evidence suggests they may have a role similar to that in mammals, where they are thought to control aspects of feeding behaviour.     

Orchid mycorrhiza: implications of a mycophagous life style

Orchid mycorrhiza probably affects about 25 000 plant species and thus roughly one tenth of all higher plants. Histologically, this symbiosis resembles other kinds of endomycorrhiza, the fungal hyphae growing within living plant cells. Considerable evidence, however, suggests that it is not a two‐way exchange relationship and thus not potentially mutualistic, such as the wide‐spread endomycorrhiza between plants and Glomalean fungi, known as arbuscular mycorrhiza. During the achlorophyllous seedling stage orchids are obligately dependent on the fungi; some species remain so through life, while others establish photosynthesis but to varying degrees remain facultatively dependent of /responsive to fungal infection as adults. None of the fungi involved are so far known to depend on the symbiosis with orchids. Transfer of organic carbon compounds from hyphae to the orchid has been demonstrated repeatedly, but it is not clear to what extent this takes place during a biotrophic phase while the intracellular hyphae remain intact, or during the subsequent extensive degradation of the hyphal coils. The advantage of viewing orchid mycorrhiza basically as a unilateral mycophagous relationship, in spite of hypothetical beneficial spin‐offs to the mycobiont, is that it provides a conceptual framework similar to that of other parasitic or fungivore relationships; mechanisms known in such relationships could be searched for in future studies of the orchid–fungus symbiosis. These could include mechanisms for recognition, attraction and selection of fungi, physiological regulation of internal hyphal growth, breakdown, and material transfer, nutritional consequences of the plant's preference(s) and trophic changes, fungal avoidance mechanisms, and consequences at population and ecosystem levels. A whole range of possible life strategies becomes apparent that could support divergent evolution and lead to the proliferation of species that has indeed occurred in the orchid family. We outline some of the possible physiological mechanisms and ecological implications of this approach.     

Throughfall Nitrogen Deposition Has Different Impacts on Soil Solution Nitrate Concentration in European Coniferous and Deciduous Forests

Increases in the deposition of atmospheric nitrogen (N) influence N cycling in forest ecosystems and can result in negative consequences due to the leaching of nitrate into groundwaters. From December 1995 to February 1998, the Pan-European Programme for the Intensive and Continuous Monitoring of Forest Ecosystems measured forest conditions at a plot scale for conifer and broadleaf forests, including the performance of time series of soil solution chemistry. The influence of various ecosystem conditions on soil solution nitrate concentrations at these forest plots (n = 104) was then analyzed with a statistical model. Soil solution nitrate concentrations varied by season, and summer concentrations were approximately 25% higher than winter ones. Soil solution nitrate concentrations increased dramatically with throughfall (and bulk precipitation) N input for both broadleaf and conifer forests. However, at elevated levels of throughfall N input (more than 10 kg N ha^–1 y^–1), nitrate concentrations were higher in broadleaf than coniferous stands. This tree-specific difference was not observed in response to increased bulk precipitation N input. In coniferous stands, throughfall N input, foliage N concentration, organic layer carbon–nitrogen (C:N) ratio, and nitrate concentrations covaried. Soil solution nitrate concentrations in conifer plots were best explained by a model with throughfall N and organic layer C:N as main factors, where C:N ratio could be replaced by foliage N. The organic layer C:N ratio classes of more than 30, 25–30, and less than 25, as well as the foliage N (mg N g^–1) classes of less than 13, 13–17, and more than 17, indicated low, intermediate, and high risks of nitrate leaching, respectively. In broadleaf forests, correlations between N characteristics were less pronounced, and soil solution nitrate concentrations were best explained by throughfall N and soil pH (0–10-cm depth). These results indicate that the responses of soil solution nitrate concentration to changes in N input are more pronounced in broadleaf than in coniferous forests, because in European forests broadleaf species grow on the more fertile soils.     

Quantitative trait loci affecting clinical mastitis and somatic cell count in dairy cattle

Norway has a field recording system for dairy cattle that includes recording of all veterinary treatments on an individual animal basis from 1978 onwards. Application of these data in a genome search for quantitative trait loci (QTL) verified genome-wise significant QTL affecting clinical mastitis on Chromosome (Chr) 6. Additional putative QTL for clinical mastitis were localized to Chrs. 3, 4, 14, and 27. The comprehensive field recording system includes information on somatic cell count as well. This trait is often used in selection against mastitis when direct information on clinical mastitis is not available. The absence of common QTL positions for the two traits in our study indicates that the use of somatic cell count data in QTL studies aimed for reducing the incidence of mastitis should be carefully evaluated. Received: 9 May 2001 / Accepted: 6 July 2001     

Relative importance of different dispersal vectors for small aquatic invertebrates in a rock pool metacommunity

The extent and frequency of passive overland dispersal of freshwater invertebrates as well as the relative importance of different dispersal vectors is not well documented. Although anecdotal evidence subscribing the feasibility of individual vectors in various aquatic systems is abundant, dispersal rates have rarely been quantified for different vectors in one study system. Earlier studies also usually investigated dispersal potential rather than actual dispersal rates. In this study we have estimated passive dispersal rates of invertebrate propagules within a cluster of temporary rock pools via water, wind and amphibians in a direct way. Overflows after heavy rains mediated dispersal of a large number of propagules through eroded channels between pools, which were collected in overflow traps. Taking into account model based predictions of overflow frequency, this corresponds with average dispersal rates of 4088 propagules/channel yr^?1. Wind dispersal rates as measured by numbers of propagules collected on sticky traps mounted between pool basins were very high (average dispersal rate: 649 propagules m^?2 in one month) and were positively related to the proximity of source populations. Finally, invertebrate propagules were also isolated from the faeces of African clawed frogs Xenopus laevis caught from the pools (on average 368 propagules/frog). The combination of short distance wind and overflow dispersal rates likely explain the dominant species sorting and mass effect patterns observed in the metacommunity in a previous study. Amphibian mediated dispersal was much less important as the Xenopus laevis population was small and migrations very rare. Based on our own results and available literature we conclude that both vector and propagule properties determine local passive dispersal dynamics of freshwater invertebrates. Accurate knowledge on rates and vectors of dispersal in natural systems are a prerequisite to increase our understanding of the impact of dispersal on ecology (colonisation, community assembly, coexistence) and evolution (gene flow, local adaptation) in fragmented environments.     

Hepatocyte growth factor activator inhibitor-1 has a complex subcellular itinerary

HAI-1 [HGF (hepatocyte growth factor) activator inhibitor-1] is a Kunitz-type transmembrane serine protease inhibitor that forms inhibitor complexes with the trypsin-like serine protease, matriptase. HAI-1 is essential for mouse placental development and embryo survival and together with matriptase it is a key regulator of carcinogenesis. HAI-1 is expressed in polarized epithelial cells, which have the plasma membrane divided by tight junctions into an apical and a basolateral domain. In the present study we show that HAI-1 at steady-state is mainly located on the basolateral membrane of both Madin-Darby canine kidney cells and mammary gland epithelial cells. After biosynthesis, HAI-1 is exocytosed mainly to the basolateral plasma membrane from where 15% of the HAI-1 molecules are proteolytically cleaved and released into the basolateral medium. The remaining membrane-associated HAI-1 is endocytosed and then recycles between the basolateral plasma membrane and endosomes for hours until it is transcytosed to the apical plasma membrane. Minor amounts of HAI-1 present at the apical plasma membrane are proteolytically cleaved and released into the apical medium. Full-length membrane-bound HAI-1 has a half-life of 1.5 h and is eventually degraded in the lysosomes, whereas proteolytically released HAI-1 is more stable. HAI-1 is co-localized with its cognate protease, matriptase, at the basolateral plasma membrane. We suggest that HAI-1, in addition to its protease inhibitory function, plays a role in transporting matriptase as a matriptase-HAI-1 complex from the basolateral plama membrane to the apical plasma membrane, as matriptase is known to interact with prostasin, located at the apical plasma membrane.     

Effects of E-Commerce on Greenhouse Gas Emissions: A Case Study of Grocery Home Delivery in Finland

In this article, we present a literature review of the general and environmental effects of e-commerce in various parts of the demand-supply chain. These are further translated into effects on greenhouse gas (GHG) emissions in the food production and consumption system. The literature study revealed many opportunities for e-commerce to reduce GHG emissions in the food production and consumption system. Some possibly negative effects were also identified. Electronic grocery shopping (e-grocery) home delivery service was chosen as the subject of a case study because of its direct and indirect potential for reducing the GHG emissions in the food production and consumption system.
GHG emission reduction potential through the implementation of various e-grocery home delivery strategies was quantified. Depending on the home delivery model used, it is possible to reduce the GHG emissions generated by grocery shopping by 18% to 87% compared with the situation in which household members go to the store themselves. We estimate that the maximum theoretical potential of e-grocery home delivery service for reducing the GHG emissions of Finland is roughly 0.3% to 1.3%; however, the current and estimated future market potential is much smaller, because the estimated market share of e-grocery services is only 10% by 2005. Narrowing the gap between the theoretical and the actual potential requires a model that would simultaneously provide additional value to the consumer and be profitable to companies. To be able to achieve significant reductions in GHG emissions, system-level innovations and changes are required. Further research is needed before conclusions can be reached as to whether e-commerce and e-grocery are useful tools in that respect.