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The Darwinian revolution in the German speaking lands was the result of a variety of influences and disciplinary convergences. One of the paths led from pre-Darwinian comparative morphology via Darwinian and Lamarckian evolutionary morphology to the Modern Synthesis. Our research demonstrates that there was no immediate replacement of one paradigm by another as described in the classical work of Thomas Kuhn. Rather, the development of novel conceptual structures looked like a Russian ‘matryoshka doll’ consisting of an over-arching ‘meta-paradigm’ embracing conceptual structures of ever smaller scale. Such a meta-paradigm for German life sciences was initially established by Johann Wolfgang von Goethe, which determined the specificity of German evolutionism throughout the 2nd half of the 19th and well into the 20th century.

Agroforestry can contribute to the mitigation of climate change while delivering multiple benefits to sub-Saharan farmers who are exposed to climate variability, land degradation, water scarcity, high disease burden and persistent poverty. But adoption is slow. Based on a critical problem solving approach and grounded theory as a strategy, we study agroforestry and subsistence agriculture as integrated, yet separate, socio-ecological systems with different organisational logics and temporal dynamics. Using ‘narrative walks’ as a qualitative method to construct grounded data, we explore the social and natural dimensions of the complex, diverse and uncertain landscape and life-worlds of subsistence agriculture. In the grounded analysis, we clarify how social stratification constructs incentives and disincentives to adopt agroforestry. To exemplify, food secure and opportunity seeking farmers may invest land and labour in trees, nurseries and social networks while risk evading farmers are constrained by the ‘food imperative’, the ‘health imperative’ and poverty in and of itself. By recognising material, symbolic and relational aspects we show how the ontology of global policies focussing on the merits of agroforestry differs from the ontology of everyday practices and strategies in subsistence agriculture. Such ontological stratification constitutes another constraint to agroforestry adoption as a comprehensive form of socio-technological change.

We combine frame analysis and transition theory into a thinking tool in sustainability science and analyse three serious and persistent problems in global health subject to sustainability impasses: HIV/AIDS, malaria, and indoor air pollution. Frame analysis identifies how problems are encased by scientific understandings and captured by transition barriers: policy cooptation, techno-institutional lock-in, and knowledge trap. Transition theory locates the transition barriers on a temporal scale and a conceptual level: landscape, regime, and niches. Frame analysis reveals how problems are embedded in particular narratives while reframing stimulates alternative understandings and problem solutions. Boundary work facilitates knowledge integration across units and transition management promotes actor oriented problem resolution. The thinking tool unites critical with problem solving research and ties reframing to analytical and temporal understandings of social change. The aim is dual: to advance methodology while stimulating critical problem solving in the quest for environmental innovations, social justice and sustainability.

Sustainability science needs approaches that allow for the integration of knowledge across disciplines and scales. This paper suggests an approach to conceptualize problems of unsustainability by embedding the Drivers-Pressure-State-Impact-Response (DPSIR) scheme within a multi-level institutional framework represented by Hagerstrand's system of nested domains. The proposed taxonomy helps to decipher and to better understand key casual chains and societal responses at the appropriate spatial levels for particular sustainability problem areas. To illustrate the scheme more concretely the example of recent problem-solving efforts for Baltic Sea eutrophication driven by Swedish agriculture is examined. The discussion focuses on how the scheme fulfills the four research strategy requirements within the field of sustainability science and how the scheme is distinct from alternative approaches. (C) 2010 Elsevier Ltd. All rights reserved. (Less)

Historically, agriculturally induced CO2 release from soils has contributed to rising levels in the atmosphere. However, by using appropriate management, soils can be turned into carbon sinks. Many of the dryland regions of the world are characterised by degraded soils, a high incidence of poverty and a low capacity to invest in agriculture. Two well-proven soil organic matter models (CENTURY 4.0 and RothC-26 3) were used two explore the effects of modifying agricultural practices to increase soil carbon stocks. The changes to land management were chosen to avoid any significant increase in energy input whilst using technologies that would be available without radically altering the current agricultural methodology. Case studies were selected from dryland farming systems in Nigeria, Sudan and Argentina. Modelling showed that it would be possible to make alterations within the structure of the current farming systems to convert these soils from carbon sources to net sinks. Annual rates of carbon sequestration in the range 0.08-0.17 Mg ha(-1) year(-1) averaged over the next 50 years could be obtained. The most effective practices were those that maximised the input of organic matter, particularly farmyard manure (up to 0.09 Mg ha(-1) year(-1)), maintaining trees (up to 0.15 Mg ha(-1) year(-1)) and adopting zero tillage (up to 0.04 Mg ha(-1) year(-1)). Verification of these predictions will require experimental data collected from field studies. (C) 2006 Elsevier B.V. All rights reserved. (Less)

The aim of this paper is to provide a cohesive categorisation of the most common sustainability assessment tools within the broader objective of lifting the understanding of tools from the environmentally-focused realm to that of the wider concept of sustainability. The framework provided is based on four main categories: indicators/indices, regional material and energy flows, life cycle approach and tools for integrated assessment. Furthermore, there is the overarching category of monetary valuation tools that can be used as a part of many of the tools listed in the subcategories above. The paper also shows that many of the tools for sustainability assessment still fail to fulfil the demands of the complex environmental, social and economic systems as proposed by the promoters of sustainability science. (Less)

For the last four decades there has been sustained scientific interest in contemporary environmental change in the Sahel (the southern fringe of the Sahara). It suffered several devastating droughts and famines between the late 1960s and early 1990s. Speculation about the climatology of these droughts is unresolved, as is speculation about the effects of land clearance on rainfall and about land degradation in this zone. However, recent findings suggest a consistent trend of increasing vegetation greenness in much of the region. Increasing rainfall over the last few years is certainly one reason, but does not fully explain the change. Other factors, such as land use change and migration, may also contribute. This study investigates the nature of a secular vegetation trend across the Sahel and discusses several potential causative factors.

That data from polar orbiting satellites have detected a widespread increase in photosynthetic activity over the last 20 years in the grasslands of the Sahel is justifies investigating its role in the tropical carbon cycle. But this task is undermined because ground data that are generally used to support the use of primary production models elsewhere are lacking. In this paper, we profile a Light Use Efficiency (LUE) model of primary production parameterised with satellite information, and test it for the West African Sahel; solar radiation is absorbed by plants to provide energy for photosynthesis, while moisture shortfalls control the efficiency of light usage. In particular, we show how an economical use of existing, yet meagre data sets can be used to circumvent nominal, yet untenable approaches for achieving this for the region. Specifically, we use a cloudiness layer provided with the NOAA/NASA 8 km Pathfinder Land data archive (PAL) data set to derive solar radiation (and other energy balance terms) required to implement the model (monthly time-step). Of particular note, we index growth efficiency via transpiration by subsuming rangeland-yield formulations into our model. This is important for partially vegetated landscapes where the fate of rainfall is controlled by relative vegetation cover. We accomplish this by using PAL-derived Normalised Difference Vegetation Index (NDVI) to partition the landscape into fractional vegetation cover. A bare soil evaporation model that feeds into bucket model is then applied, thereafter deriving actual transpiration (quasi-daily time-step). We forgo a formal validation of the model due to problems of spatial scale and data limitations. Instead, we generate maps showing model robustness via Monte Carlo simulation. The precision of our Gross Primary Production (GPP) estimates is acceptable, but falls off rapidly for the northern fringes of the Sahel. We also map the locations where errors in the driving variables are mostly responsible for the bulk of uncertainty in predicted GPP, in this case the water stress factor and the NDVI. Comparisons with an independent model of primary production, CENTURY, are relatively poor, yet favourable comparisons are made with previous primary production estimates found for the region in the literature. A spatially exhaustive evaluation of our GPP map is carried out by regressing randomly sampled observations against integrated NDVI, a method traditionally used to quantify absolute amounts of primary production. Our model can be used to quantify stocks and flows of carbon in grasslands over the recent historical period.

Using the UNFCCC as a basis, and the objectives of estimating soil organic carbon (SOC) changes during the period 1900-2100, a spatially explicit database of climate, land cover and soil texture was compiled for a 262,000 km(2) region in semi-arid Sudan. The area is characterized by low input cultivation of millet, sorghum and sesame combined with livestock grazing. By integrating the database with the CENTURY ecosystem model, we were able to estimate historical, current and future pools of SOC as a function of land management and climate. The SOC (upper 20 cm) decrease from 1900 to 2000 was estimated to be 6.8 Mt and the maximum potential carbon sink (SOC increase) for the period 2000 to 2 100 was estimated to be 17 Mt. Cropland and grassland lost 293 and 152t SOC km(-2) respectively whereas the savannahs gained 76t SOC km(-2) from 1900 to 2000. The SOC sequestration scenario simulated during 2000-2100 recovered 94, 84 and 75 tkm(-2) for cropland, grassland and savannah respectively. In addition to climate and soils, cropping intensity, fallow periods, fire frequency and grazing intensity also influence cropland SOC variation. Grassland and savannah SOC variations depend on grazing intensity and fire return interval. Land management may affect future amounts of SOC in semi-arid areas thereby turning them from sources into sinks of carbon. SOC estimates were reasonably consistent with measurements (r(2) = 0.70, n = 13). (Less)

Summary The timing and pattern of cranial neural crest cell emergence and migration in the Mexican axolotl, Ambystoma mexicanum, are assessed using scanning electron microscopy (SEM). Cranial neural crest cells emerge and begin to migrate at the time of neural fold closure and soon form three distinct streams. The most anterior (mandibular) stream emerges first, at the level of the mesencephalon. Cells in this stream migrate rostroventrally around the optic vesicle. The second (hyoid) and third (branchial) streams emerge in close succession at the level of the rhombencephalon and extend ventrolaterally. Cells forming the hyoid stream migrate rostral to the otic vesicle, whereas the branchial stream divides into two parallel streams, which migrate caudal to the otic vesicle. At later stages (stage 26 onwards) the cranial neural crest cells disperse into the adjacent mesoderm and can no longer be followed by dissection and SEM. The pattern of cranial neural crest emergence and migration, and division into migratory streams is similar to that in other amphibians and in the Australian lungfish ( Neoceratodus forsteri). Emergence of crest cells from the neural tube, relative to the time of neural tube closure, occurs relatively late in comparison to anurans, but much earlier than in the Australian lungfish. These results establish a morphological foundation for studies in progress on the further development and fate of cranial neural crest cells in the Mexican axolotl, as well as for studies of the role of cranial neural crest in cranial patterning.

Summary Direct development is a specialized reproductive mode that has evolved repeatedly in many different lineages of amphibians, especially anurans. A fully formed, albeit miniature adult hatches directly from the egg; there is no free-living larva. In many groups, the evolution of direct development has had profound consequences for cranial development and morphology, including many components that are derived from the embryonic neural crest. Yet, the developmental bases of these effects remain poorly known. In order to more fully characterize these changes, we used three molecular markers to analyze cranial neural crest-cell emergence and migration in the direct-developing frog, Eleutherodactylus coqui: HNK-1 immunoreactivity, Dlx protein expression, and cholinesterase activity. Our study validates and extends earlier results showing that the comprehensive changes in embryonic cranial patterning, differentiation, and developmental timing that are associated with direct development in Eleutherodactylus have not affected gross features of cranial neural crest biology: the relative timing of crest emergence and the number, configuration and identity of the principal migratory streams closely resemble those seen in metamorphic anurans. The three markers are variably expressed within and among neural crest-cell populations. This variation suggests that determination of cranial neural crest-cells may already have begun at or soon after the onset of migration, when the cells emerge from the neural tube. It is not known how or even if this variation correlates with differential cell lineage or fate. Finally, although HNK-1 expression is widely used to study neural crest migration in teleost fishes and amniotes, E. coqui is the only amphibian known in which it effectively labels migrating neural crest-cells. There are not enough comparative data to determine whether this feature is functionally associated with direct development or is instead unrelated to reproductive mode.

The contribution of cranial neural crest cells to the development and patterning of cranial muscles in amphibians was investigated in the phylogenetically basal and morphologically generalized frog, Bombina orientalis. Experimental methods included fluorescent marking of premigratory cranial neural crest and extirpation of individual migratory streams. Neural crest cells contributed to the connective tissue component, but not the myofibers, of many larval muscles within the first two branchial arches (mandibular and hyoid), and complex changes in muscle patterning followed neural crest extirpation. Connective tissue components of individual muscles of either arch originate from the particular crest migratory stream that is associated with that arch, and this relationship is maintained regardless of the segmental identity—or embryonic derivation—of associated skeletal components. These developmental relations define a pattern of segmentation in the head of larval anurans that is similar to that previously described in the domestic chicken, the only vertebrate that has been thoroughly investigated in this respect. The fundamental role of the neural crest in patterning skeleton and musculature may represent a primitive feature of cranial development in vertebrates. Moreover, the corresponding developmental processes and cell fates appear to be conserved even when major evolutionary innovations—such as the novel cartilages and muscles of anuran larvae—result in major differences in cranial form.

Photosynthetically Active Radiation (PAR) is important for assessing both the impact of changing land cover on climate, and for modelling productivity on a regional scale, as well as its potential in areas that are vulnerable to food shortfalls. A relatively simple method that generates spatially comprehensive and representative values of PAR at time scales of 10-days (dekads) or longer is described, tested and implemented over a portion of West Africa. With simple equations to describe the geographical and temporal variation of global radiation receipt at the top of the atmosphere, daily cloud flags from the NOAA/NASA AVHRR Pathfinder Land Data Set (PAL) are used in conjunction with an empirical formula developed by Angstrom and constants tailored to West African conditions to estimate surface receipt of global radiation there. Ground observations of PAR from the HAPEX Sahel experiment (at 13°66′ N and 2°53′ E from 1992) are used to parameterise the relative sunshine duration variable in the Angstrom relation so as to minimise errors between observed and modelled PAR. Results indicate that PAR may be estimated to within 20 percent of observed values for 28 out of 36 10-day summation periods over a year. End-of-year accumulated PAR is estimated to within 1.96 percent. Normalised root mean square errors (NRMSEs) and normalised mean absolute errors (NMAEs) of 15.69 percent and 12.46 percent, respectively, were obtained for 10-day sums, with values of 10.96 percent and 8.74 percent, respectively, for monthly sums. The spatial variability of end-of-year PAR for 1992 is in accordance with what was expected. Though more accurate methods exist for achieving this, the technique is merited for its ease of application, using an accessible data set, over areas where solar irradiation measurements are lacking.

Certain peptides with sequences related to part of the major histocompatibility complex class I antigen enhance the action of insulin. These peptides also aggregate into fibrous structures that seem to be related to their biological activity. In the current study, the 17-residue peptide with amino acid sequence Gly-Asn-Glu-Gln-Ser-Phe-Arg-Val-Asp-Leu-Arg-Thr-Leu-Leu-Arg-Tyr-Ala is used as a representative example of these bioactive molecules. As seen by electron microscopy, the peptide associates into gently twisted ribbons, 50 A thick, in which the amount of twist decreases as the ribbons become wider. X-ray diffraction analysis suggests that the peptides are arranged as in an antiparallel beta-sheet extending essentially endlessly along the fiber axis. The amino acid sequence of the peptide is such that one side of the beta-sheet is predominantly polar while the opposite side is nonpolar. This allows the beta-sheets to form multilayers with alternating hydrophobic and hydrophilic interfaces. The length of the extended peptide (approximately 54 A) determines the thickness of the ribbon and the tendency of individual beta-sheets to twist accounts for the twisting of the ribbons. An alternative model is also discussed, again based on antiparallel beta-sheets, but with adjacent sheets interdigitated in a "side-by-side" fashion rather than forming stacked layers. Comparable inactive peptides such as Gly-Asn-Glu-Gln-Ser-Ala-Arg-Val-Asp-Leu-Arg-Thr-Leu-Leu-Arg-Tyr-Tyr (changed amino acids underlined) do not form ordered filamentous structures.

An automated computer-controlled sequential reading monochromator system for optical emission spectrometry with an inductively-coupled plasma as source is described. The system selects the set of emission lines which are best suited for each type of sample. Multi-element analysis of major and trace elements is done automatically, including sample changing, calibration, background correction and presentation of results.

The formation of borate complexes contributes significantly to the distribution coefficients obtained in the separation of polyhydroxy acids in borate medium. A study of a large number of straight-chain hydroxy acids shows that these contributions tend to increase with the number of vicinal hydroxyl groups and with their distance from the carboxylate group. Vicinal hydroxyl groups in gauche conformation have the ability to form strong complexes, provided that the steric conditions are favourable in other respects. The contributions of vicinal hydroxyl groups in anti conformation are much less.

Complex mixtures of aromatic compounds can be rapidly separated on anion-exchangers in the acetate form with acetic acid as eluent and determined automatically by recording the absorbance in the ultraviolet. Carboxylates are separated by ion-exchange. Hydrogen bonds between non-disso-ciated acids and the counter-ions influence the distribution coefficients. Hydrogen-bonding with the resin has a marked effect on the sorption of solutes containing phenolic protons. Intramolecular hydrogen-bonding depresses their sorption. Hydrophobic interactions have a predominant influence with hydrocarbons and with phenolic compounds containing non-polar aliphatic substituents. The relative importance of these interactions increases with a decreased ion-exchange capacity of the resin.

A method to efficiently antigen-prime B-lymphocytes with low amounts (less than 1 microgram/10(8) cells) of either immunogenic or non-immunogenic molecules is described. Keyhole limpet hemocyanin (KLH) and histone were used as prototypes for strongly immunogenic and for phylogenetically conserved non-immunogenic epitopes, respectively. Several modifications of previously reported methods were applied to the system and resulted in the requirement of antigen amounts sufficiently low to be obtainable by elution of proteins from electrophoretic gels. Antigen priming against highly purified antigen preparations is thereby feasible even when purified material cannot be obtained by conventional biochemical procedures. The amount of T- and B-lymphocytes and interleukin-2 production was estimated under various conditions during the priming procedure, and those optimal for generation of a high number of antigen-specific B-lymphocytes determined. In vitro antigen-primed B-lymphocytes were immortalized by conventional hybridoma technology. By fusion of lymphoid cells with myeloma cells at each day during the antigen-priming period, the optimal day of fusion to generate antigen-specific hybridomas was determined. Further, in 12 experiments with different antigens, 11 monoclonal antibodies to histones H3 and H4, two to the murine glucose transporter, 17 to trinitrophenyl-sheep red blood cells, and 20 to KLH were obtained. All specific hybridomas produced IgMs, as the antigen-priming period could not be extended for more than 9-10 days, whereafter a rapid decay in B-lymphocytes occurred.

A monoclonal antibody, designated NAT-9 II:3F-6F (IgM), was generated by hybridization of mouse myeloma cells with spleen cell from mice immunized with normal human bone marrow cells. The antibody reacted with 40-60% of bone marrow cells as analysed on samples from 40 normal individuals and only with a subpopulation of human acute myeloid leukemia (AML) cells of the M2 class (20/20 tested) and M4 class (12/12 tested) (subclasses of the French-American-British (FAB) classification), but not with leukemic cells of the M1 (0/12 tested) and M5 (0/12 tested) FAB subclasses. This is in contrast to many other myeloid-specific monoclonal antibodies. Fluorescence-activated cell sorter (FACS) analyses and morphological examination of cells stained with peroxidase as based on the NAT-9 II:3F-6F monoclonal antibody showed that this antibody reacted with a distant differentiation antigen which is absent on myeloblasts, but expressed on promyelocytes, myelocytes, metamyelocytes, band neutrophils, and on a minority of mature granulocytes. NAT-9 II:3F-6F did not bind to circulating monocytes, T and B cells, erythrocytes and a variety of different human cell culture lines. Immunoblotting demonstrated that the antibody bind to a cellular component with a Mr approximately 97.400 dalton. The antibody may be useful in immunological subclassification of non-lymphoid leukemias and in studies on hematopoiesis.

A monoclonal antibody (designated K:1–6F) generated by hybridization of mouse myeloma cells with spleen cells from mice immunized with the erythroleukemic cell line K562 was found by fluorescence-activated cell sorter analysis, dot-blot assay and electroimmunoblotting to bind to a majority of cells in the K562 and HEL erythroleukemic cell lines, to a subset of cells of the erythroid lineage from normal bone marrow, to a subset of cells in all analysed cases (total 10) of erythroleukemia, and weakly to cells from patients with myeloid leukemia. The antibody did not bind to normal erythrocytes, monocytes, T- and B lymphocytes or granulocytes, as well as a panel of human malignant cell lines of hemopoietic origin (HL60, U937, Daudi, Molt-3, RH-L4 and U266). Biochemical characterization of the antigen defined by the antibody suggests that the epitope is defined by a carbohydrate structure alone or in combination with proteins. Four molecules with M, 100 kD, 65 kD, 45 kD and 18 kD respectively were immunoprecipitated from Triton X-100 extract of K562 erythroleukemia cells. Neuraminidase did not affect the binding of the antibody, whereas tunicamycin reduced the K:1–6F expression. The K:1–6F Mab was in normal bone marrow found to be specific for erythroid precursor cells and may therefore be useful in examination of normal and leukemic erythropoiesis.

The distribution coefficients of a large number of chlorinated phenols and phenolic compounds containing two aromatic nuclei have been determined on cross-linked polyvinylpyrrolidone and on anion exchangers in the acetate form. Solutes with low affinity for polyvinylpyrrolidone have been separated in 1 mM hydrochloric acid, while 3–7 M acetic acid has been used for chlorinated compounds. Acetic acid is a suitable eluent in chromatography on anion exchangers. Hydrogen bonding of phenolic protons to the resins, together with non-polar interactions, are mainly responsible for the sorption on both of these types of resins. Under the applied conditions, the relative importance of hydrogen bonding is greater for polyvinylpyrrolidone than for the anion exchanger.

The retention volumes of a large number of aromatic compounds in acetic acid and dilute hydrochloric acid were determined on two pellicular polyamide resins. With carboxylic acids, ion exchange is an important sorption mechanism in dilute eluents. Hydrogen bonding of the hydroxyl proton to the carbonyl group in the polyamide is the dominant sorption mechanism for non-electrolytes that contain hydroxyl groups. Intramolecular hydrogen bonding decreases the sorption of ortho-substituted solutes containing hydroxyl groups. Several solutes were separated within a few minutes but greater separation factors were required than in experiments with small, uniform beads.

Aromatic compounds containing hydroxyl and carboxyl groups are retained in aqueous medium by cross-linked polyvinylpyrrolidone due to hydrogen bonding, with the resin serving as a proton acceptor. Efficient separations were obtained in 0.001 M hydrochloric acid. With substances containing seveal proton-donating groups, improved results were obtained by using a more efficient eluent, e.g., 5 M acetic acid.