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In this paper we show that explicit treatment of risks and uncertainties is an essential element in planning sustainable agricultural development. Introduction of risks and uncertainties in production models considerably alter strategies for achieving robust outcomes. We discuss stochastic models that may assist to derive optimal agricultural production allocation and expansion within environmental and health risk indicators. Approaches are illustrated with the example of spatially-explicit livestock production allocation in China to 2030.

Europe's agricultural land (including Ukraine) comprise of 164 million hectares of cultivated land and 76 million hectares of permanent pasture. A "food first" paradigm was applied in the estimations of land potentially available for the production of biofuel feedstocks, without putting at risk food supply or nature conservation. Three land conversion scenarios were formulated: (i) A base scenario, that reflects developments under current policy settings and respects current trends in nature conservation and organic farming practices, by assuming moderate overall yield increases; (ii) an environment oriented scenario with higher emphasis on sustainable farming practices and maintenance of biodiversity; and (iii) an energy oriented scenario considering more substantial land use conversions including the use of pasture land. By 2030 some 44-53 million hectares of cultivated land could be used for bioenergy feed-stock production. The energy oriented scenario includes an extra 19 million hectares pasture land for feedstocks for second-generation biofuel production chains. Available land is foremost to be found in Eastern Europe, where substantial cultivated areas can be freed up through sustainable gains in yield in the food and feed sector. Agricultural residues of food and feed crops may provide an additional source for biofuel production. When assuming that up to 50% of crop residues can be used without risks for agricultural sustainability, we estimate that up to 246 Mt agricultural residues could be available for biofuel production, comparable to feedstock plantations of some 15-20 million hectares.

IIASA's agro-ecological zones modelling framework has been extended for biofuel productivity assessments distinguishing five main groups of feedstocks covering a wide range of agronomic conditions and energy production pathways, namely: woody lignocellulosic plants, herbaceous lignocellulosic plants, oil crops, starch crops and sugar crops. A uniform Pan-European land resources database was compiled at the spatial resolution of 1 km2. Suitability and productivity assessments were carried out by matching climate characteristics with plant requirements, calculating annual biomass increments or yields including consideration of soil and terrain characteristics of each grid-cell. Potential biomass productivity and associated energy yields were calculated for each grid-cell. Spatial distributions of suitabilities of biofuel feedstocks in Europe were generated for each individual feedstock as well as for the five biofuel feedstock groups. Estimated agronomical attainable yields, both in terms of biomass (kg ha-1) as well as biofuel energy equivalent (GJ ha-1), were mapped and tabulated by agriculture and pasture land cover classes as derived from the CORINE land cover database. Results have been further aggregated by administrative units at NUTS 2 level.

The current hot debate on biofuels calls for a balanced and realistic long-term strategy for biofuels. The REFUEL project provides several ingredients for such a strategy. Analyses in this project indicate that domestically produced biofuels can cover a significant share of EU fuel demand in the coming decades, with the EU-12 new member states and Ukraine as most promising regions. This potential can be realised with residual streams and on existing agricultural land, without conversion of e.g. nature reserves. Second generation biofuels are essential for the long-term success of biofuels due to their superior performance in many ways. But generally, the key challenge for the near future would be how to enhance the development of biofuels in a responsible way, i.e. stimulating the production chains with the best performance, and preventing negative impacts e.g., by paying careful attention to possible system impacts of biofuel production such as indirect land use changes and rising food prices. Finally, 2nd generation biofuels require specific policy: the precursor role of 1st generation is overrated, both in technical terms as well as in their role as market precursors. When it comes to synergies, 2nd generation biofuels might benefit more from other developments in the energy sector, such as initiatives in co-firing of biomass for (heat and) power, than from 1st generation biofuels, also because of the public resistance that the latter induce.

Synaptophysin, an integral membrane protein of synaptic vesicles in nerve terminals and a class of small translucent vesicles in neuroendocrine cells, was detected in intact rabbit platelets by immunoblotting, immunofluorescence staining and immuno-electron microscopy. In a highly purified preparation of serotonin organelles isolated from rabbit platelets, synaptophysin was enriched approximately 10-15-fold over platelet homogenate. About 80% of total platelet synaptophysin was present in this purified fraction. The apparent molecular mass (approximately 38 kDa) and the extent of glycosylation of platelet-derived synaptophysin was more similar to the neuronal than to the neuroendocrine form of the protein. Immunofluorescence microscopy revealed that synaptophysin was compartmentalized in intact rabbit platelets and immuno-electron microscopy of subcellular fractions showed that it was localized exclusively to the membrane surface of serotonin organelles. No synaptophysin-like immunoreactivity was detected in platelets from other species such as human, guinea pig and rat. Another integral membrane protein of synaptic vesicles, p65, and a family of synaptic vesicle-associated phosphoproteins, the synapsins, were not detected in platelets of any species tested. These results provide evidence that serotonin organelles from rabbit platelets share a subset of protein components with synaptic vesicles from neurons. Synaptophysin in serotonin organelles from rabbit platelets, as suggested for small synaptic vesicles in neurons, might play a role in the formation of protein channels for the exocytotic release of serotonin.

A comprehensive assessment of the impacts of climate change on agro-ecosystems over this century is developed, up to 2080 and at a global level, albeit with significant regional detail. To this end an integrated ecological–economic modelling framework is employed, encompassing climate scenarios, agro-ecological zoning information, socio-economic drivers, as well as world food trade dynamics. Specifically, global simulations are performed using the FAO/IIASA agro-ecological zone model, in conjunction with IIASAs global food system model, using climate variables from five different general circulation models, under four different socio-economic scenarios from the intergovernmental panel on climate change. First, impacts of different scenarios of climate change on bio-physical soil and crop growth determinants of yield are evaluated on a 5′×5′ latitude/longitude global grid; second, the extent of potential agricultural land and related potential crop production is computed. The detailed bio-physical results are then fed into an economic analysis, to assess how climate impacts may interact with alternative development pathways, and key trends expected over this century for food demand and production, and trade, as well as key composite indices such as risk of hunger and malnutrition, are computed. This modelling approach connects the relevant bio-physical and socio-economic variables within a unified and coherent framework to produce a global assessment of food production and security under climate change. The results from the study suggest that critical impact asymmetries due to both climate and socio-economic structures may deepen current production and consumption gaps between developed and developing world; it is suggested that adaptation of agricultural techniques will be central to limit potential damages under climate change.

Ro 63-1908, 1-[2-(4-hydroxy-phenoxy)-ethyl]-4-(4-methyl-benzyl)-piperidin-4-ol, is a novel subtype-selective N-methyl-D-aspartate (NMDA) antagonist that has been characterized in vitro and in vivo. Ro 63-1908 inhibited [(3)H]dizocilpine ((3)H-MK-801) binding in a biphasic manner with IC(50) values of 0.002 and 97 microM for the high- and low-affinity sites, respectively. Ro 63-1908 selectively blocked recombinant receptors expressed in Xenopus oocytes containing NR1C + NR2B subunits with an IC(50) of 0.003 microM and those containing NR1C + NR2A subunits with an IC(50) of100 microM, thus demonstrating greater than 20,000-fold selectivity for the recombinant receptors expressing NR1C + NR2B. Ro 63-1908 blocked these NMDA NR2B-subtype receptors in an activity-dependent manner. Ro 63-1908 was neuroprotective against glutamate-induced toxicity and against oxygen/glucose deprivation-induced toxicity in vitro with IC(50) values of 0.68 and 0.06 microM, respectively. Thus, the in vitro pharmacological characterization demonstrated that Ro 63-1908 was a potent and highly selective antagonist of the NR2B subtype of NMDA receptors. Ro 63-1908 was active against sound-induced seizures (ED(50) = 4.5 mg/kg i.p. when administered 30 min beforehand) in DBA/2 mice. The dose required to give a full anticonvulsant effect did not produce a deficit in the Rotarod test. NMDA-induced seizures were also inhibited by Ro 63-1908 with an ED(50) of 2.31 mg/kg i.v. when administered 15 min before testing. Ro 63-1908 gave a dose-related neuroprotective effect against cortical damage in a model of permanent focal ischemia. Maximum protection of 39% was seen at a plasma concentration of 450 ng/ml. There were, however, no adverse cardiovascular or CNS side-effects seen at this dosing level.

Common understanding of the causes of land-use and land-cover change is dominated by simplifications which, in turn, underlie many environment-development policies. This article tracks some of the major myths on driving forces of land-cover change and proposes alternative pathways of change that are better supported by case study evidence. Cases reviewed support the conclusion that neither population nor poverty alone constitute the sole and major underlying causes of land-cover change worldwide. Rather, peoples' responses to economic opportunities, as mediated by institutional factors, drive land-cover changes. Opportunities and constraints for new land uses are created by local as well as national markets and policies. Global forces become the main determinants of land-use change, as they amplify or attenuate local factors. © 2001 Elsevier Science Ltd. All rights reserved.

Agreements to mitigate climate change have been hampered by several things, not least their cost. But the cost might well be more acceptable if we had a clear picture of what damages would be avoided by different levels of emissions reductions, in other words, a clear idea of the pay off. The problem is that we do not. The Third Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) published this year (IPCC (2001a) and IPCC (2001b)) lists a wide range of potential impacts but has difficulty in discriminating between those that are critical in their nature and magnitude from those that are less important. Yet, the identification of critical impacts (e.g. ones that should be avoided at any reasonable cost) is obviously a key to addressing targets for mitigating climate change. Indeed, a central objective of the UN Framework Objective on Climate Change (UNFCCC) is to avoid “dangerous levels” of climate change that could threaten food security, ecosystems and sustainable development (areas of risk that are specifically mentioned in UNFCCC Article 2). For several years, we have been researching impacts in key areas of risk: hunger, water shortage, exposure to malaria transmission, and coastal flooding, as part of a global fast-track assessment (Parry and Livermore, 1999). 1 The results of our work have been reported widely and form a significant part of the IPCC's assessment of likely impacts (IPCC (2001a) and IPCC (2001b)). But they are scattered through different parts of the IPCC report and other literature and, before now, we have not brought them together. For this review, we have graphed our estimates of effects as a single measure: the additional millions of people who could be placed at risk as a result of different amounts of global warming ( Fig. 1). Full-size image (36K) - Opens new window Full-size image (36K) Fig. 1. Additional millions at risk due to climate change in 2050s and 2080s for hunger, coastal flooding, water shortage and malaria. The width of the curve indicates one standard deviation of variance around the mean, based on results from four HadCM2 experiments (Parry and Livermore, 1999; IPCC, 2000). Solid lines indicate model-based estimates. Dotted lines are inferred ( IPCC (2001a) and IPCC, 2001b. Climate change 2001: The Scientific Basis. Technical Summary of the Working Group I Report, Geneva, 2001.IPCC (2001b)) and intended as schematic. Stab. 450 (etc.)=stabilisation@450 ppmv (etc.). View Within Article The figure shows the increase in millions at risk due to higher temperatures for two time periods—2050s and 2080s. The analysis takes into account likely non-climate developments such as growth in population, and income and developments of technology, and these become important assumptions behind future trends in, for example, increases in crop yield and the building of coastal defences. These developments themselves have very great effects on the numbers at risk and represent a (non-climate change) reference case. The graph thus shows the additional millions at risk due specifically to estimated future changes in climate. But now for the caveats: the reference case is only for one future world (what the IPCC used to call a best estimate or “business-as-usual” future, now referred to as IS92a). More recently, the IPCC has explored a set of six different developmental pathways that the world may follow (IPCC, 2000), and the millions at risk in these alternative futures will certainly differ. Our work on these is in hand but will probably take a year to complete. We need also to emphasise that the graph is a global estimate which hides important regional variations and, so far, it is based on one model of future climate patterns (the UK's Hadley Centre second generation global climate model) ( Johns et al., 1997). While these are the only global impact estimates currently available, we need urgently to complete similar ones for different climate models and for a variety of development pathways. Five important points emerge from this figure. First, the curves of additional millions at risk generally become steeper over time. Less obviously, this results as much from a larger and more vulnerable exposed population in 2080 than in 2050, as from increases in temperature or inferred changes in precipitation and sea-level rise. For example, the remarkable steepness of the water shortage curve in 2080 is the outcome of very large city populations in China and India becoming newly at risk. In the case of hunger, however, the rising curve in 2080 stems from widespread heat stress of crops, while up to about 2050 lesser amounts of warming lead to yield gains in temperate regions that balance losses elsewhere and lead to only small net increases in hunger (Parry and Livermore, 1999). These complex interactions between exposure and climate change tell a clear story: there will be more millions at risk as time progresses. Secondly, the figure indicates how much we need to reduce emissions in order to draw-down significantly the numbers at risk. We have estimated effects assuming that atmospheric concentrations of CO2 are stabilised at 750 parts per million (ppmv) by 2250 and at 550 ppmv by 2150 (Arnell, in press). These are approximately equivalent, respectively, to 10 times and 20 times the reduction in emissions assumed in the Kyoto Protocol. The 750 ppmv target delays the damage but does not avoid it. By 2080, it would halve the number at risk from hunger and flooding, reduce the population at risk of malaria by perhaps a third and water shortage by about a quarter. But to bring risk levels down from hundreds to tens of millions would require a stabilisation target of about 550 ppmv. We have also indicated on the graph, but only in a schematic form, the approximate locations of 450, 650 and 1000 ppmv stabilisation pathways and their effect on millions at risk (IPCC (2001a) and IPCC (2001b)). Although impact analyses have not yet been conducted for these stabilisation levels, it appears that the 450 ppmv pathway would achieve very great reductions in millions at risk, although very high costs of mitigation would be incurred. It is precisely this kind of pay-off that needs to be analysed properly. A third conclusion is that information is now available that can help inform the selection of climate change targets. Thus far these targets, such as Kyoto, have been chosen in broadly a top–down manner, without clear knowledge of the impacts that would be avoided, and that has been partly their weakness. Now we may argue, for example, that in order to keep damages below an agreed tolerable level (for example, a given number of additional people at risk) global temperature increases would need to be kept below a given amount; and emissions targets could then be developed to achieve that objective. Fourthly, it is clear that mitigation alone will not solve the problem of climate change. Adaptation will be necessary to avoid, or at least reduce, much of the possible damage, and since we need many of the benefits of adaptation today, regardless of climate change in the future (e.g. increased drought protection of agriculture, improved flood defences, more efficient use of water, better malaria control), many of the adaptive strategies for climate change can be “win–win”. We need to find a blend of mitigation and adaptation to meet the challenge of climate change. Mitigation can buy time for adaptation (for example, delaying impacts until improved technology and management can handle them), and adaptation can raise thresholds of tolerance that need to be avoided by mitigation (for example, by increasing drought tolerance of crops). Considered separately, they appear inadequate to meet such a challenge, but combined they would make a powerful response.

The increasing human population in developing countries is exerting pressure on finite land resources, frequently causing overexploitation and land degradation. Sectoral and single-objective approaches to planning for the alleviation of this situation have often not been effective, and an integrated approach is required that involves all stakeholders, accommodates the qualities and limitations of each land unit, and produces viable land use options (FAO, 1995).

Future world population growth is fuelled by two components: the demographic momentum, which is built into the age composition of current populations, and changes in reproductive behaviour and mortality of generations yet to come. This paper investigates, by major world regions and countries, what we know about population growth, what can be projected with reasonable certainty, and what is pure speculation. The exposition sets a frame for analysing demographic driving forces that are expected to increase human demand and pressures on land and water resources. These have been contrasted with current resource assessments of regional availability and use of land, in particular with estimates of remaining land with cultivation potential. In establishing a balance between availabilty of land resources and projected needs, the paper distinguishes regions with limited land and water resources and high population pressure from areas with abundant resources and low or moderate demographic demand. Overall, it is estimated that two–thirds of the remaining balance of land with rainfed cultivation potential is currently covered by various forest ecosystems and wetlands. The respective percentages by region vary between 23% in Southern Africa to 89% in South–Eastern Asia. For Latin America and Asia the estimated share of the balance of land with cultivation potential under forest and wetland ecosystems is about 70%, in Africa this is about 60%. If these were to be preserved, the remaining balance of land with some potential for rainfed crop cultivation would amount to some 550 million hectares. The regions which will experience the largest difficulties in meeting future demand for land resources and water, or alternatively have to cope with much increased dependency on external supplies, include foremost Western Asia, South–Central Asia, and Northern Africa. A large stress on resources is to be expected also in many countries of Eastern, Western and Southern Africa.

Rat embryonic hippocampal neurons cultured on astrocyte feeder-layers were sensitive to different excitotoxic stimuli after 10-12 DIV. Almost all neurons (approximately 95%) died within 20 h after a transient exposure for 10 min to 50 microM glutamate, a continuous exposure to either 25 microM NMDA or 250 microM kainate or after a 15-min deprivation of glucose and oxygen. Dizocilpine at 10 microM protected neurons against the glutamate- and NMDA-mediated toxicity as well as against 30 min glucose and oxygen deprivation. However, it failed to protect against kainate toxicity and prolonged glucose/oxygen deprivation (60 min). An additional treatment with CNQX (100 microM) protected neurons even under the latter two conditions. This indicates that the vast majority of neurons was sensitive to different excitotoxic stimuli acting through different types of glutamate receptors leading to calcium overload of the cells which might be the common denominator of triggering cell death under these conditions. Expression of calcium-binding proteins, such as calbindin D28K or calretinin, might increase the intracellular calcium buffer capacity of neurons, thus, rendering them more resistant to calcium overload. Therefore, we analysed whether neurons expressing these calcium-binding proteins would survive these toxic stimuli. Indeed, a small population of the neurons (3-5%) survived, including a subpopulation of calretinin-positive but not calbindin D28K-positive neurons. This implies that the expression of calcium-binding proteins per se does not render neurons more resistant towards these excitotoxic stimuli. Moreover, most of the surviving calretinin-positive neurons showed morphological damage as indicated by loss of neurites. When cytotoxicity due to calcium overload was induced by an exposure of the cells to the calcium ionophore 4-bromo-A23187 rather than by activation of glutamate receptors, calretinin-positive cells were found not to be significantly more resistant than the vast majority of neurons. This may indicate that the lower sensitivity of a subpopulation of calretinin-positive neurons to excitotoxic stimuli may be due to a lower expression of glutamate receptors.

Monoclonal M6 antibody binds to the surface of murine central nervous system neurons as well as to apical surfaces of epithelial cells in the choroid plexus and proximal tubules of the kidney. M6 antigen is expressed in the central nervous system as early as embryonic day 10, most strongly in the marginal zone of the neural tube, and remains detectable in adulthood. IgG or Fab fragments of M6 antibody interfere with the extension of neurites by cultured cerebellar neurons. Effects of the antibody on neurite extension are readily detectable after 24 h. No reduction of cell viability is detected during the first 3 days of antibody treatment. Cultures maintained in the presence of antibody for longer than 5 days exhibit reduced viability of neurons. This reduction in long-term viability in the presence of M6 antibody is largely avoided when 25 mM KCl is included in the culture medium. The antibody-mediated perturbation of neurite outgrowth is not blocked by the presence of elevated KCl. The unusually short and flattened appearance of neurites in these cultures suggests that the M6 antibody selectively affects neurite extension. Time-lapse cinematography of anti-M6-treated neurons reveals no apparent effect on movement of lamellipodia and filopodia of growth cones. Only the overall extension of the neurite appears to be inhibited. M6 antigen is a 35 kD glycoprotein that can be isolated from a deoxycholate- (DOC) solubilized membrane fraction from adult mouse brain.

Aus der notwendigen Existenz Verteilter Systeme und der von ihnen geforderten Eigenschaften wird eine zentrale Verwaltung dieser Systeme begrundet. Die Aufgaben dieser Verwaltung werden beschrieben und Werkzeuge in Form eines Netzmanagementsystems gefordert. Die teilweise Realisierung eines solchen Systems fur ein heterogenes Netz, das im operationeilen Einsatz ist, wird dargestellt. Fur die unterschiedlichen Teilnetze wurden einzelne Komponenten selbst entwickelt, andere auf dem Markt erhaltliche integriert und dem Konzept angepast.

The impact of land use on the global carbon cycle and climate is assessed. The Bern carbon cycle-climate model was used with land use maps from HYDE3.0 for 1700 to 2000 A.D. and from post-SRES scenarios for this century. Cropland and pasture expansion each cause about half of the simulated net carbon emissions of 188 Gt C over the industrial period and 1.1 Gt C yr -1 in the 1990s, implying a residual terrestrial sink of 113 Gt C and of 1.8 Gt C yr -1 , respectively. Direct CO 2 emissions due to land conversion as simulated in book-keeping models dominate carbon fluxes due to land use in the past. They are, however, mitigated by 25% through the feedback of increased atmospheric CO 2 stimulating uptake. CO 2 stimulated sinks are largely lost when natural lands are converted. Past land use change has eliminated potential future carbon sinks equivalent to emissions of 80–150 Gt C over this century. They represent a commitment of past land use change, which accounts for 70% of the future land use flux in the scenarios considered. Pre-industrial land use emissions are estimated to 45 Gt C at most, implying a maximum change in Holocene atmospheric CO 2 of 3 ppm. This is not compatible with the hypothesis that early anthropogenic CO 2 emissions prevented a new glacial period. DOI: 10.1111/j.1600-0889.2008.00340.x

A computer-based measuring strategy to determine spatial orientation of short glass fibers from the cross-section of single fibers is presented. A way of correcting the inclination-dependent probability of hitting a fiber is shown as well as the correction of fiber-end intersections. The latter is done by pattern recognition and application of a set of FORTRAN subroutines. 9 references.

The main aim of the Food and Agriculture Program is to explore alternative solutions to the world's food problem. Towards this end a system of linked models will be used for policy analysis over a medium time horizon. The Basic Linked System of the FAP consists of national models which describe in detail the food and agriculture system of the corresponding country and contain a rather aggregate mapping of the respective nonagricultural sector. The interdependencies of the two sectors are modelled as well. In this paper, the methodological and computational requirements a model should fulfill in order to become linkable with the FAP's model system are discussed and an overview of the structure of the national models of those countries which were built at IIASA by members of the FAP is given. A national model consists of three components: one for supply, one for demand and a third describing the process of policy decision-making. The policy module provides a mapping from the objectives the policymakers pursue while deciding on policies into the space of policy instruments. Endogenizing the process of setting the level of the policy instruments rather than specifying them exogenously over the whole time span the model runs introduces more realism into the model, because governments react to changes occurring outside and/or inside of their country. The supply module consists of two subcomponents—one for agriculture and one for nonagriculture. The complexity of the decision-making process in agriculture is reduced to a two-stage process. In the first stage, farmers decide on the level of inputs they want to use for production. At the subsequent stage, these inputs are allocated to the various production activities and hence the amount of each commodity produced is decided on. The allocation process is modelled by using a nonlinear optimization program with statistically estimated parameters. Nonagricultural production is described in terms of a Cobb-Douglas function. For modelling demand an extended linear expenditure system is used. For developing countries the total population is divided into two income classes, whereas for developed countries the population is assumed to be homogeneous from the point of view of demand. The models are linked by applying the theory of general equilibrium. The markets are cleared simultaneously at the national and international level. It is assumed that supply cannot adjust during the exchange process and that the policy instruments are predetermined as well.

We investigated whether the L2/HNK-1 carbohydrate epitope, expressed by two unusual glycolipids and several neural adhesion molecules, including L1, neural cell adhesion molecule, J1, and the myelin-associated glycoprotein, is involved in adhesion. Monoclonal L2 antibodies, the L2/HNK-1-reactive, sulfate-3-glucuronyl residue carrying glycolipids (L2 glycolipid) and a tetrasaccharide derived from the L2 glycolipid (L2 tetrasaccharide) were added to microexplant cultures of early postnatal mouse cerebellum, and cell migration and process extension were monitored. On the substrate poly-D-lysine, Fab fragments of L2 antibodies, L2 glycolipid, and L2 tetrasaccharide inhibited outgrowth of astrocytic processes and migration of cell bodies, but only L2 glycolipid and L2 tetrasaccharide reduced neurite outgrowth. On laminin, L2 antibodies, L2 glycolipid, and L2 tetrasaccharide inhibited outgrowth of astrocytic processes. Additionally, L2 glycolipid and L2 tetrasaccharide inhibited cell migration and neurite outgrowth. Several negatively charged glycolipids, lipids, and saccharides were tested for control and found to have no effect on outgrowth patterns, except for sulfatide and heparin, which modified outgrowth patterns in a similar fashion as L2 glycolipid and L2 tetrasaccharide. On astrocytes none of the tested compounds interfered with explant outgrowth. In short-term adhesion assays L2 glycolipid, sulfatide, and heparin inhibited adhesion of neural cells to laminin. L2 glycolipid and sulfatide interfered with neuron to astrocyte and astrocyte to astrocyte adhesion, but not with neuron-neuron adhesion. The most straightforward interpretation of these observations is that the L2/HNK-1 carbohydrate and the sulfated carbohydrates, sulfatide and heparin, act as ligands in cell adhesion.

To probe for the role of the L1 cell surface glycoprotein during neurite outgrowth and fasciculation in the early postnatal mouse cerebellar cortex, a microexplant culture system was used. Fasciculation of neurites was reduced in the presence of antigen- binding fragments (Fab) of poly- and monoclonal L1 antibodies, as compared to untreated controls. In addition, speed of neurite outgrowth was enhanced in the presence of antibodies. Migration of cell bodies of small neurons was also significantly increased. Very similar effects on these outgrowth parameters were observed with Fab fragments from poly- and monoclonal neural cell adhesion molecule (N-CAM) antibodies. Antibodies from preimmune sera had no effect. These findings suggest that L1 antigen not only plays a role in adhesion of isolated neural cell bodies and migration of granule cell neurons in the early postnatal mouse cerebellar cortex (Lindner et al., 1983; Rathjen and Schachner, 1984), but also in neurite outgrowth and fasciculation.

It could be demonstrated that the determination of CS2 in water and waste water is generally not affected by solids in lower quantities. An alkalization is recommended in the presence of hydrogen sulphide.

When explants or reaggregates of small neurons from early postnatal mouse cerebella are plated on a mixture of laminin and poly-d-lysine, one observes small cells with an orientation of processes largely perpendicular to the direction of granule cell neurites after several days. These cells first have a bipolar morphology and then elaborate a rich dendritic arbor-like structure opposite a long, thin axon-like process. Several lines of evidence suggest that these cells are the small inhibitory interneurons of the cerebellar cortex: They take up GABA, express high levels of the embryonic form of N-CAM, do not express L1, the oligodendrocyte marker O4, or the glial marker vimentin, and display ultrastructural features reminiscent of stellate and/or basket cells in vivo. These observations suggest that the elaboration of directional positioning of small inhibitory interneurons can be studied in culture, thus offering the possibility to elucidate the cellular and molecular mechanisms underlying the orientation of particular neural cells with regard to others.

1) A heat-stable activator of human sulphatase A (cerebroside sulphatase) was purified from human liver. It is required for the enzymatic degradation of cerebroside sulphates (sulphatides) in buffers (ionic strength greater than or equal 0.2) with osmolarity in the physiological range. 2) The purification steps involve extraction, acetone precipitation, heat treatment, isoelectric focusing and gel filtration. 3) Based on the definition of a specific activator unit, the purification of the final preparation was approximately 2000-fold over the acetone precipitation and several thousand-fold in the overall procedure. 4) The purified activator migrated as a single protein band when subjected to gel electrophoresis. Its effect was abolished after treatement with pronase E. The apparent molecular weight as determined by gel filtration was 21 500 +/- 1500; the isoelectric point was 4.3. 5) The activating effect of this protein factor and of taurodeoxycholate on cerebroside sulphatase activity was compared on a weight and molar basis.

After the analyses of the impact of agricultural trade liberalization presented in the preceding chapters of this book, the questions naturally arise: What are the major findings and what do they mean for policy? To what extent do the results reflect reality and to what extent can they be ascribed to the characteristics of the analytical tool used? What are the methodological or analytical lessons to be learned from the study? These questions are addressed in this chapter. Before addressing them, however, it would be useful to reiterate the scope of the study.

A hormonally defined culture medium is described which supports survival and proliferation of astroglia from primary cultures of early postnatal mouse cerebellum. This medium consists of bovine serum albumin, insulin, transferrin, selenium, hyaluronic acid, protease inhibitor aprotinin, and epidermal growth factor. Trypsin-dissociated single cerebellar cell suspensions are plated in this medium on poly- l -lysine-coated glass coverslips and maintained for two weeks before subcultivation. After subcultivation into defined medium more than 99% of all cells are vimentin-positive and fibronectin- and almost completely glial fibrillary acid (GFA) protein-negative, indicating that these cells are less mature astrocytes. After replacement of defined medium by culture medium containing 10% horse serum, expression of GFA protein is detectable in addition to vimentin by indirect immunofluorescence.

It is useful to describe at the outset the analytical tool or model and the scheme of analysis used to obtain the economic and social consequences of removing protection. We begin by examining the essential as well as desirable properties of any tool for analyzing the issues addressed. Then, in Section 3.2, we justify our approach and briefly describe our analytical tool, the Basic Linked System (BLS), in a nontechnical fashion. The scheme of analysis followed (including a description of the notion of trade liberalization in this study, the alternative scenarios, the approach used to explain the results of scenarios, and the welfare indicators used to evaluate the results) is described in Section 3.3.

1) An activator protein necessary for the enzymic hydrolysis of cerebroside sulphate could be partially purified from unfractionated rat liver. This activator, which is similar to that of human origin, proved to be a heat-stable, non-dialyzable, low molecular weight protein with an isoelectric point of 4.1. Its activity could be destroyed by pronase. 2) For elucidation of the subcellular localization of the activator, rat liver was fractionated by differential centrifugation. The intracellular distribution of the cerebroside sulphatase activator was compared to the distribution patterns of marker enzymes for different cell organelles and found to coincide with the lysosomal arylsulphatase, thus indicating a lysosomal localization. 3) This was confirmed using highly purified secondary, i.e. iron-loaded, lysosomes. After disruption by osmotic shock, these organelles hydrolyzed cerebroside sulphate when incubations were performed under physiological conditions with endogenous as well as exogenous sulphatase A as enzyme. 4) After subfractionation of the disrupted secondary lysosomes into membrane and lysosol fractions by high speed centrifugation, it was found that the activator protein was exclusively associated with the lysosol, whereas the acid hydrolases were distributed differently between the two fractions. 5) The lysosol was further fractionated by semi-preparative electrophoresis on polyacrylamide gels. Two protein fractions were obtained: a high molecular weight fraction, containing the activator-free acid hydrolases, and a low molecular weight fraction, containing the enzyme-free activator of cerebroside sulphatase. 6) The significance of these findings for the hydrolysis of sphingolipids in the lysosomes is discussed.

Almost all governments in the world intervene in the determination of agricultural production and prices. As a consequence, international trade in agricultural products is affected. This is not a new phenomenon, as governments have done so from very early times for various reasons, such as to safeguard adequate food supplies, to extract resources from farm populations, or to exchange agricultural products for other desired commodities and services. These objectives still characterize agricultural policies in many developing countries today and, to some extent, also in the developed industrial countries. While in developing countries, because of the dominance of agriculture in employment and production, the major objective is often extraction of resources from the agricultural sector for the development of the entire economy, in developed countries relatively few people are still engaged in agricultural production, so supporting the incomes of these few at levels comparable to the rest of the population is the major objective of intervention. A multitude of interventions that influence domestic agriculture in virtually all countries has led to considerable distortions in international trade in the contemporary world.

A hormonally defined medium is described which facilitates the survival of small neurons in primary cultures of mouse cerebellum. The defined medium consists of bovine serum albumin, insulin, transferrin, selenium, thyroxine, and the protease inhibitor aprotinin. About 95% of all cells were identified as neurons using tetanus toxin as a marker in an immunocytochemical assay. They survive for more than 4 weeks, showing a tendency to grow in cell clusters with a dense network of processes. The remaining cells (approximately 5%) were identified as astrocytes by their expression of vimentin and GFA protein and the lack of expression of fibronectin.

Important aims in neurobiology are to understand the processes which determine the differentiation of neural cells in brain tissue; of primary interest is that of the main neural cell types neurons, astrocytes and oligodendrocytes. One may assume that signals via direct cell-cell contact and interactions of cells with the extracellular matrix are important as well as signals via diffusible factors like hormones, growth or differentiation factors. Because such complex signals can often not be readily studied in detail in intact tissue, cell cultures have been utilized to follow differentiation of cells in less complex systems. The best experimental control of the cellular environment (contact environment and composition of diffusible factors) is thought to be possible in monolayer cultures. Therefore, an idealized experiment would be to start with a homogenous population of precursor cells of one of the main neural cell types which will become fully differentiated cells after a series of defined manipulations concerning cell contact environment, growth and differentiation factors, hormonal and nutritional requirements.

As we have seen in the preceding chapter, the countries liberalizing agricultural trade, in general, seem to gain from it. However, the countries that do not liberalize are often affected adversely. In particular, a number of developing countries lose when the OECD countries liberalize agricultural trade, though some of them gain when they themselves liberalize. It is thus interesting to see what happens when both OECD countries and the developing countries liberalize agricultural trade together.

To gain insight into the cellular and molecular mechanisms underlying cell interactions in the early postnatal mouse cerebellum, Ca2+-dependent and -independent aggregation mechanisms were characterized using single cell suspensions under conditions that allow discrimination between the two mechanisms. When cerebellar cells were derived from newborn to 10-day-old mouse cerebellum, both mechanisms were active and showed no major change in activity during this time period. Mg2+ could not replace Ca2+ in the Ca2+-dependent mechanism. In contrast to the Ca2+-independent mechanisms, the Ca2+-dependent mechanism was inactive at low temperatures, suggesting a necessity for molecular rearrangement within the surface membrane during aggregation. Neuraminidase, chondroitinase, heparinase or hyaluronidase treatment of cells did not influence the aggregation of cells under Ca2+-dependent and -independent conditions. Chondroitin sulfate inhibited and hyaluronic acid stimulated the Ca2+-dependent mechanism, whereas chondroitin sulfate only slightly and hyaluronic acid strongly inhibited the Ca2+-independent one. Dextran sulfate slightly inhibited both mechanisms, whereas heparin and fucoidan, a complex sulfated carbohydrate, did not influence cell aggregation, while they strongly inhibited attachment of cells to laminin. The polycation poly-L-lysine slightly stimulated the Ca2+-independent mechanism, but inhibited the Ca2+-dependent one. Interestingly, chondroitin sulfate and hyaluronic acid strongly stimulated cell aggregation under conditions where both mechanisms were almost destroyed or inactive. Dextran sulfate showed only a small effect under these conditions. These observations indicate that different molecular mechanisms are active in cell-cell versus cell-extracellular matrix interactions and suggest a hitherto unknown complexity in molecular mechanisms during early postnatal cerebellar development.

Among the OECD countries, agricultural protection is an important issue of trade negotiations. In fact, the OECD Council of Ministers has given the secretariat a mandate to study the impact of agricultural trade liberalization by OECD countries. Thus, a scenario to explore the impact of agricultural liberalization by OECD countries is of specific policy interest.

The reference scenario described in this chapter is basically a “business as usual” scenario. Past policy regimes, as embodied in the price transmission regressions, are continued in this scenario.

The CAP of the EC is often regarded as a policy that distorts global agricultural trade significantly. Since, as seen in Chapter 5, the OECD countries gain from agricultural trade liberalization, it is of interest to see what would be the impacts of a unilateral trade liberalization by the EC, globally and on its domestic situation. However, to appreciate the impact of the removal of the currently pursued CAP by the EC, one first needs to know the objectives of the CAP. These are (Commission of the EC, 1958): (1) To increase agricultural productivity by developing technical progress and by ensuring the national development of agricultural production and the optimal utilization of the factors of production, particularly labor. (2) To ensure thereby a fair standard of living for the agricultural population, particularly by increasing the individual earnings of persons engaged in agriculture. (3) To stabilize markets. (4) To guarantee regular supplies. (5) To ensure reasonable prices in supplies to consumers.

The role of cerebroside sulfate in the specific binding of opiates to the synaptic membrane was investigated by the use of the enzyme, sulfatase A (cerebroside sulfatase, cerebroside-3-sulfate-3-sulphohydrolyase, EC 3.1.6.8). It was observed that the hydrolysis of sulfatides in the synaptic membrane by this enzyme was dependent on the presence of a heat stable protein molecule. When [3H]naloxone binding to the enzyme-treated membrane was determined, specific binding was attenuated. This inhibition of specific binding was dependent on the concentration of the activator molecule and could not be prevented by the addition of bovine serum albumin in the binding assay mixtures. The enzymatic pH optimum for inhibiting the specific opiate binding was between pH 4.7 and 5.0. This correlated well with the pH optimum for the sulfatase A to hydrolyze free cerebroside sulfate molecules. Scatchard analysis indicated a significant decrease in the number of binding sites with no statistically significant alteration in binding affinity of the remaining sites.

The activator of sulphatase A is necessary for the enzymic degradation of sulphatides to cerebrosides at ionic concentrations in the physiological range (1).

The case for liberalization and removal of protection is in some senses stronger, and in others weaker, for the developing countries. The increased efficiency of allocation to which liberalization leads should be especially important for a poor country. The directly unproductive rent-seeking activities that are encouraged by dis tort ionary protective policies waste real resources, including entrepreneurial talents, which are particularly scarce in developing countries.

The purpose of this paper is to exemplify a means by which an integrated assessment can be made of global and regional effects on land use of climate change. This is achieved by use of data on the effects of climate change on world food prices as inputs to a regional land use allocation model. Data on world prices are drawn from a recent global study of climate change and crop yields. In a case study of England and Wales a land allocation model is used to infer changes of land use that are the product of the integrated effect of climate-induced global price changes and climate-related changes of yield in England and Wales. This combination of changed prices and yield potential is used to calculate the land use providing the highest returns for each of 155,235 1 km2 cells of land in England and Wales for a future assumed for the year 2060 (without climate change) and then for that same environment with climate change. The difference between these two is then treated as an estimated effect resulting from climate change.