Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

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Insect herbivore- associated organisms affect plant responses to herbivory
Zhu, F. ; Poelman, E.H. ; Dicke, M. - \ 2014
New Phytologist 204 (2014)2. - ISSN 0028-646X - p. 315 - 321.
spodoptera-littoralis - mediated interactions - indirect defense - host - virus - symbionts - parasites - caterpillars - arabidopsis - hypothesis
In nature, plants interact with many organisms and need to integrate their responses to these diverse community members. Knowledge on plant-insect relationships has accumulated rapidly during the last decades. Yet most studies on direct or indirect defences of plants against herbivory have treated herbivores as individual stressors. However, herbivores often consist of communities themselves, comprising organisms such as parasites and symbionts, which may have important effects on the herbivore phenotype, and consequently on interactions of the herbivore with its food plant. Here, we review how herbivore-associated organisms affect plant-herbivore interactions. Organisms associated with herbivores can directly affect how a plant interacts with their herbivorous hosts, by interfering with plant signal-transduction pathways, repressing the expression of plant defence-related genes, or altering plant secondary metabolism. In addition, herbivore-associated organisms can also affect plant responses indirectly by their effect on the behaviour and physiology of their herbivore host. The changes in plant phenotype that arise from herbivore-associated organisms may subsequently affect interactions with other community members, thereby impacting community dynamics. Furthermore, herbivore-associated organisms may act as a hidden driving force of plant-herbivore coevolution. Therefore, to understand plant-herbivore interactions it is important to realize that every single herbivorous insect constitutes a community in itself.
Diversity of pyrrolizidine alkaloids in native and invasive Senecio pterophorus (Asteraceae): Implications for toxicity
Castells, E. ; Mulder, P.P.J. ; Perez -Trujillo, M. - \ 2014
Phytochemistry 108 (2014). - ISSN 0031-9422 - p. 137 - 146.
increased competitive ability - mass-spectrometry - enemy release - chemical diversity - hypothesis - plants - biosynthesis - evolution - metabolism - defense
Changes in plant chemical defenses after invasion could have consequences on the invaded ecosystems by modifying the interactions between plants and herbivores and facilitating invasion success. However, no comprehensive biogeographical studies have yet determined the phenotypic levels of plant chemical defenses, as consumed by local herbivores, covering large distributional areas of a species. Senecio pterophorus is a perennial shrub native to Eastern South Africa, expanded into Western South Africa and introduced into Australia and Europe. As other Asteraceae, S. pterophorus contains pyrrolizidine alkaloids (PAs) toxic to vertebrate and invertebrate herbivores. Here we analyzed S. pterophorus PAs by LC–MS/MS on foliage sampled across its entire distributional range, including the native and all non-native areas. PA concentrations and diversity was very high: we found 57 compounds belonging to 6 distinct necine base-types, including the highly toxic 1,2-unsaturated PAs (retronecine and otonecines) and the less toxic 1,2-saturated PAs (platynecine and rosmarinecines). Plants from different origins diverged in their PA absolute and relative concentrations. Rosmarinine was the most abundant compound in Australia and South Africa, but it was nearly absent in Europe. We characterized three plant chemotypes: retrorsine–senkirkine chemotype in Eastern South Africa, rosmarinine chemotype in Australia and Western South Africa, and acetylseneciphylline chemotype in Europe. PA absolute concentrations were highest in Australia. The increased absolute and relative concentrations of retronecine PAs from Australia and Europe, respectively, indicate that S. pterophorus is potentially more toxic in the invasive range than in the native range.
Novel chemistry of invasive plants: exotic species have more unique metabolomic profiles than native congeners
Macel, M. ; Vos, R.C.H. de; Jansen, J.J. ; Putten, W.H. van der; Dam, N.M. van - \ 2014
Ecology and Evolution 4 (2014)13. - ISSN 2045-7758 - p. 2777 - 2786.
increased competitive ability - climate-change - pyrrolizidine alkaloids - inbreeding depression - chemical diversity - evolution - herbivore - weapons - hypothesis - defenses
It is often assumed that exotic plants can become invasive when they possess novel secondary chemistry compared with native plants in the introduced range. Using untargeted metabolomic fingerprinting, we compared a broad range of metabolites of six successful exotic plant species and their native congeners of the family Asteraceae. Our results showed that plant chemistry is highly species-specific and diverse among both exotic and native species. Nonetheless, the exotic species had on average a higher total number of metabolites and more species-unique metabolites compared with their native congeners. Herbivory led to an overall increase in metabolites in all plant species. Generalist herbivore performance was lower on most of the exotic species compared with the native species. We conclude that high chemical diversity and large phytochemical uniqueness of the exotic species could be indicative of biological invasion potential.
The evolution of the placenta drives a shift in sexual selection in livebearing fish
Pollux, B.J.A. ; Meredith, R.W. ; Springer, M.S. ; Garland, T. ; Reznick, D.N. - \ 2014
Nature 513 (2014). - ISSN 0028-0836 - p. 233 - 236.
parent-offspring conflict - molecular phylogenetic-relationships - mosquitofish gambusia-holbrooki - reproductive mode - size dimorphism - poeciliidae cyprinodontiformes - maximum-likelihood - viviparity - hypothesis - gene
The evolution of the placenta from a non-placental ancestor causes a shift of maternal investment from pre- to post-fertilization, creating a venue for parent–offspring conflicts during pregnancy1, 2, 3, 4. Theory predicts that the rise of these conflicts should drive a shift from a reliance on pre-copulatory female mate choice to polyandry in conjunction with post-zygotic mechanisms of sexual selection2. This hypothesis has not yet been empirically tested. Here we apply comparative methods to test a key prediction of this hypothesis, which is that the evolution of placentation is associated with reduced pre-copulatory female mate choice. We exploit a unique quality of the livebearing fish family Poeciliidae: placentas have repeatedly evolved or been lost, creating diversity among closely related lineages in the presence or absence of placentation5, 6. We show that post-zygotic maternal provisioning by means of a placenta is associated with the absence of bright coloration, courtship behaviour and exaggerated ornamental display traits in males. Furthermore, we found that males of placental species have smaller bodies and longer genitalia, which facilitate sneak or coercive mating and, hence, circumvents female choice. Moreover, we demonstrate that post-zygotic maternal provisioning correlates with superfetation, a female reproductive adaptation that may result in polyandry through the formation of temporally overlapping, mixed-paternity litters. Our results suggest that the emergence of prenatal conflict during the evolution of the placenta correlates with a suite of phenotypic and behavioural male traits that is associated with a reduced reliance on pre-copulatory female mate choice.
Habitat-Specific Effects of Fishing Disturbance on Benthic Species Richness in Marine Soft Sediments
Denderen, P.D. van; Hintzen, N.T. ; Rijnsdorp, A.D. ; Ruardij, P. ; Kooten, T. van - \ 2014
Ecosystems 17 (2014)7. - ISSN 1432-9840 - p. 1216 - 1226.
pleuronectes-platessa l. - southern north-sea - sole solea-solea - trawl disturbance - ecosystem-model - productivity - diversity - communities - bottom - hypothesis
Around the globe, marine soft sediments on continental shelves are affected by bottom trawl fisheries. In this study, we explore the effect of this widespread anthropogenic disturbance on the species richness of a benthic ecosystem, along a gradient of bottom trawling intensities. We use data from 80 annually sampled benthic stations in the Dutch part of the North Sea, over a period of 6 years. Trawl disturbance intensity at each sampled location was reconstructed from satellite tracking of fishing vessels. Using a structural equation model, we studied how trawl disturbance intensity relates to benthic species richness, and how the relationship is mediated by total benthic biomass, primary productivity, water depth, and median sediment grain size. Our results show a negative relationship between trawling intensity and species richness. Richness is also negatively related to sediment grain size and primary productivity, and positively related to biomass. Further analysis of our data shows that the negative effects of trawling on richness are limited to relatively species-rich, deep areas with fine sediments. We find no effect of bottom trawling on species richness in shallow areas with coarse bottoms. These condition-dependent effects of trawling suggest that protection of benthic richness might best be achieved by reducing trawling intensity in a strategically chosen fraction of space.
The Predictive Adaptive Response: Modeling the Life-History Evolution of the Butterfly
Heuvel, J. van den; Saastamoinen, M. ; Brakefield, P.M. ; Kirkwood, T.B. ; Zwaan, B.J. ; Shanley, D.P. - \ 2013
American Naturalist 181 (2013)2. - ISSN 0003-0147 - p. E28 - E42.
phenotypic plasticity - metabolic syndrome - body-size - adaptation - starvation - growth - flight - lepidoptera - temperature - hypothesis
A predictive adaptive response (PAR) is a type of developmental plasticity where the response to an environmental cue is not immediately advantageous but instead is later in life. The PAR is a way for organisms to maximize fitness in varying environments. Insects living in seasonal environments are valuable model systems for testing the existence and form of PAR. Previous manipulations of the larval and the adult environments of the butterfly Bicyclus anynana have shown that individuals that were food restricted during the larval stage coped better with forced flight during the adult stage compared to those with optimal conditions in the larval stage. Here, we describe a state-dependent energy allocation model, which we use to test whether such a response to food restriction could be adaptive in nature where this butterfly exhibits seasonal cycles. The results from the model confirm the responses obtained in our previous experimental work and show how such an outcome was facilitated by resource allocation patterns to the thorax during the pupal stage. We conclude that for B. anynana, early-stage cues can direct development toward a better adapted phenotype later in life and, therefore, that a PAR has evolved in this species
Flightlessness affects cranial morphology in birds
Gussekloo, S.W.S. ; Cubo, J. - \ 2013
Zoology : Analysis of Complex Systems 116 (2013)2. - ISSN 0944-2006 - p. 75 - 84.
phylogenetic analysis - genome sequences - aves - evolution - palaeognathae - characters - hypothesis - palatinum - reveals - complex
Flightless birds belonging to phylogenetically distant clades share several morphological features in the pectoral and pelvic apparatus. There are indications that skull morphology is also influenced by flightlessness. In this study we used a large number of flightless species to test whether flightlessness in modern birds does indeed affect cranial morphology. Discriminant analyses and variation partitioning show evidence for a relationship between skull morphology and the flightless condition in birds. A possible explanation for the change in cranial morphology can be linked to the reduced selective force for light-weight skulls in flightless birds. This makes an increase in muscle mass, and therefore an enlargement of muscle insertion areas on the skull, possible. We also compared the ontogenetic trajectory of Gallus with the adult morphology of a sample of flightless species to see whether the apomorphic features characterizing the skull of flightless birds share the same developmental basis, which would indicate convergent evolution by parallelism. Skull morphology (expressed as principal component scores) of palaeognathous flightless birds (ratites) is dissimilar (higher scores) to juvenile stages of the chicken and therefore seem peramorphic (overdeveloped). Principal component scores of adult neognathous flightless birds fall within the range of chicken development, so no clear conclusions about the ontogenetic trajectories leading to their sturdier skull morphology could be drawn
Response to Ravnskov et al. on saturated fat and CHD
Pedersen, J.I. ; Norum, K.R. ; James, P.T. ; Brouwer, I.A. ; Katan, M.B. ; Clarke, R. ; Elmadfa, I. ; Kris-Etherton, P.M. ; Kromhout, D. ; Margetts, B.M. ; Mensink, R.P. ; Rayner, M. ; Uusitupa, M. - \ 2012
The British journal of nutrition 107 (2012)3. - ISSN 0007-1145 - p. 458 - 460.
heart-disease - cholesterol - atherosclerosis - hypothesis - mortality - statins
Contrasting patterns of herbivore and predator pressure on invasive and native plants
Engelkes, T. ; Wouters, B. ; Bezemer, T.M. ; Harvey, J.A. ; Putten, W.H. van der - \ 2012
Basic and Applied Ecology 13 (2012)8. - ISSN 1439-1791 - p. 725 - 734.
below-ground enemies - climate-change - insect herbivores - communities - populations - competition - hypothesis - evolution - release
Invasive non-native plant species often harbor fewer herbivorous insects than related native plant species. However, little is known about how herbivorous insects on non-native plants are exposed to carnivorous insects, and even less is known on plants that have recently expanded their ranges within continents due to climate warming. In this study we examine the herbivore load (herbivore biomass per plant biomass), predator load (predator biomass per plant biomass) and predator pressure (predator biomass per herbivore biomass) on an inter-continental non-native and an intra-continental range-expanding plant species and two congeneric native species. All four plant species co-occur in riparian habitat in north-western Europe. Insects were collected in early, mid and late summer from three populations of all four species. Before counting and weighing the insects were classified to trophic guild as carnivores (predators), herbivores, and transients. Herbivores were further subdivided into leaf-miners, sap-feeders, chewers and gallers. Total herbivore loads were smaller on inter-continental non-native and intra-continental range-expanding plants than on the congeneric natives. However, the differences depended on time within growing season, as well as on the feeding guild of the herbivore. Although the predator load on non-native plants was not larger than on natives, both non-native plant species had greater predator pressure on the herbivores than the natives. We conclude that both these non-native plant species have better bottom-up as well as top-down control of herbivores, but that effects depend on time within growing season and (for the herbivore load) on herbivore feeding guild. Therefore, when evaluating insects on non-native plants, variation within season and differences among feeding guilds need to be taken into account.
Vertebrate time-tree elucidates the biogeographic pattern of a major biotic change around the K-T boundary in Madagascar
Crottinia, A. ; Madsen, O. ; Poux, C. ; Straussa, A. ; Vieites, D.R. ; Vences, M. - \ 2012
Proceedings of the National Academy of Sciences of the United States of America 109 (2012)14. - ISSN 0027-8424 - p. 5358 - 5363.
species richness - ocean currents - dispersal - diversification - divergence - hypothesis - vicariance - phylogeny - evolution - radiation
The geographic and temporal origins of Madagascar's biota have long been in the center of debate. We reconstructed a time-tree including nearly all native nonflying and nonmarine vertebrate clades present on the island, from DNA sequences of two single-copy protein-coding nuclear genes (BDNF and RAG1) and a set of congruent time constraints. Reconstructions calculated with autocorrelated or independent substitution rates over clades agreed in placing the origins of the 31 included clades in Cretaceous to Cenozoic times. The two clades with sister groups in South America were the oldest, followed by those of a putative Asian ancestry that were significantly older than the prevalent clades of African ancestry. No colonizations from Asia occurred after the Eocene, suggesting that dispersal and vicariance of Asian/Indian groups were favored over a comparatively short period during, and shortly after, the separation of India and Madagascar. Species richness of clades correlates with their age but those clades that have a large proportion of species diversity in rainforests are significantly more species-rich. This finding suggests an underlying pattern of continuous speciation through time in Madagascar's vertebrates, with accelerated episodes of adaptive diversification in those clades that succeeded radiating into the rainforests.
Winter distribution of Greater Scaup Aythya marila in relation to available food resources
Cervencl, A. ; Fernandez, S.A. - \ 2012
Journal of Sea Research 73 (2012). - ISSN 1385-1101 - p. 41 - 48.
lesser scaup - diving ducks - wadden sea - aquatic birds - tufted ducks - salinity - fuligula - hypothesis - selection - bivalves
The European wintering population of Greater Scaup has declined significantly over the last 20 years and some of the main threats appear to be at the wintering grounds. This contribution aims at describing the local distribution of Scaup in the Dutch Wadden Sea, one of the most important wintering sites for Scaup in relation to available food resources. Data on the distribution of Scaup was obtained from annual aerial counts in January during 1999–2009. This data was related to benthos data of regular shellfish surveys in the sublittoral part of the western Dutch Wadden Sea. Boosted regression tree models were applied to quantify the relative importance of different potential prey items to explain the presence of Scaup. Scaup preferred sites with high abundances of small sized Mya arenaria. A negative influence on Scaup preference for sites with high abundances M. arenaria was found when there was a high abundance of large Cerastoderma edule at the sites, which increased Scaup searching time for M. arenaria.
Understanding trait interactions and their impacts on growth in Scots pine branches across Europe.
Sterck, F.J. ; Martinez-Vilalta, J. ; Mencuccini, M. ; Cochard, H. ; Gerrits, P. ; Zweifel, R. ; Herrero, A. ; Korhonen, J.F.J. ; Llorens, P. ; Nikinmaa, E. ; Nole, A. ; Poyatos, R. ; Ripullone, F. ; Sass-Klaassen, U. - \ 2012
Functional Ecology 26 (2012)2. - ISSN 0269-8463 - p. 541 - 549.
xylem cavitation resistance - stress-induced cavitation - hydraulic efficiency - functional traits - tree structure - pit membranes - trade-offs - drought - adjustment - hypothesis
1. Plants exhibit a wide variety in traits at different organizational levels. Intraspecific and interspecific studies have potential to demonstrate functional relationships and trade-offs amongst traits, with potential consequences for growth. However, the distinction between the correlative and functional nature of trait covariation presents a challenge because traits interact in complex ways. 2. We present an intraspecific study on Scots pine branches and use functional multi-trait concepts to organize and understand trait interactions and their impacts on growth. Branch-level traits were assessed for 97 branches from 12 Scots pine sites across Europe. 3. To test alternative hypotheses on cause-effect relationships between anatomical traits, hydraulic traits and branch growth, we measured for each branch: the tracheid hydraulic diameter, double cell wall thickness, cell lumen span area, wood density, cavitation vulnerability, wood-specific hydraulic conductivity, the leaf area to sapwood area ratio and branch growth. We used mixed linear effect models and path models to show how anatomical traits determine hydraulic traits and, in turn, how those traits influence growth. 4. Tracheid hydraulic diameter was the best predictor of cavitation vulnerability (R-2 = 0 09 explained by path model) and specific conductivity (R-2 = 0 19) amongst anatomical traits. Leaf area to sapwood area ratio had the strongest direct effect on branch growth (R-2 = 0 19) and was positively associated with the tracheid hydraulic diameter (R-2 = 0 22). A number of bivariate correlations between traits could be explained by these functional relationships amongst traits. 5. The plasticity in tracheid hydraulic diameter (10.0-15.1 mu m) and leaf area to sapwood area ratio (600-6051 cm(2) cm(-2)) and the maintenance of a minimum leaf water potential (between) 2 and) -2.5 MPa) appear to drive the anatomical and hydraulic traits of Scots pine across Europe. These properties are major drivers of the functional trait network underlying the growth variation amongst pine branches and thus possibly contribute to the ecological success of pines at a local and continental scale.
Is love for green in our genes? A critical analysis of evolutionary assumptions in restorative environments research
Joye, Y. ; Berg, A.E. van den - \ 2011
Urban Forestry and Urban Greening 10 (2011)4. - ISSN 1618-8667 - p. 261 - 268.
landscape preference - stress recovery - responses - scenes - hypothesis - psychology - biophilia - health - beauty
Within the field of restorative environments research, it is commonly assumed that restorative responses, triggered by exposure to natural elements and settings, are ultimately adaptive traits originating from our species’ long evolutionary history in natural environments. The aim of this article is to critically investigate the viability of this evolutionary view on restoration. In doing so, we specifically focus on Stress Recovery Theory (SRT), as this theoretical framework has most extensively elaborated on the supposed evolutionary origins of restoration. A detailed analysis of SRT's psycho-evolutionary framework shows that neither current empirical evidence nor conceptual arguments provide any strong support for the hypothesis of restorative responses to nature as an ancient evolved adaptive trait. Based on this conclusion we put forward an alternative model for restorative responses to nature based on processing fluency, which prima facie circumvents some of the pitfalls associated with evolutionary accounts for restoration. The Discussion section reflects on the implications of our critical discussion for the theory and practice of urban forestry and urban greening.
Mental budgeting and the management of household finance
Antonides, G. ; Groot, I.M. de; Raaij, W. van - \ 2011
Journal of Economic Psychology 32 (2011)4. - ISSN 0167-4870 - p. 546 - 555.
future consequences - behavior - decisions - choice - consumption - hypothesis - psychology - outcomes - income - money
Mental budgeting and financial management were investigated in a large sample of the Dutch population. Mental budgeting was quite common, and was explained from general education, having saving goals, financial knowledge, time orientation, and financial situation. Also, mental budgeting, in addition to effects of financial situation, time orientation and financial knowledge, was positively associated with having an overview of expenses and current accounts, and household financial management
Reef fishes of Saba Bank, Netherlands Antilles : Assemblage structure across a gradient of habitat types
Toller, W. ; Debrot, A.O. ; Vermeij, M. ; Hoetjes, P.C. - \ 2010
PLoS ONE 5 (2010)5. - ISSN 1932-6203 - 13 p.
coral-reef - seagrass beds - community structure - species richness - mangroves - nursery - biodiversity - hypothesis - complexity - islands
Saba Bank is a 2,200 km2 submerged carbonate platform in the northeastern Caribbean Sea off Saba Island, Netherlands Antilles. The presence of reef-like geomorphic features and significant shelf edge coral development on Saba Bank have led to the conclusion that it is an actively growing, though wholly submerged, coral reef atoll. However, little information exists on the composition of benthic communities or associated reef fish assemblages of Saba Bank. We selected a 40 km2 area of the bank for an exploratory study. Habitat and reef fish assemblages were investigated in five shallow-water benthic habitat types that form a gradient from Saba Bank shelf edge to lagoon. Significant coral cover was restricted to fore reef habitat (average cover 11.5%) and outer reef flat habitat (2.4%) and declined to near zero in habitats of the central lagoon zone. Macroalgae dominated benthic cover in all habitats (average cover: 32.5 – 48.1%) but dominant algal genera differed among habitats. A total of 97 fish species were recorded. The composition of Saba Bank fish assemblages differed among habitat types. Highest fish density and diversity occurred in the outer reef flat, fore reef and inner reef flat habitats. Biomass estimates for commercially valued species in the reef zone (fore reef and reef flat habitats) ranged between 52 and 83 g/m2. The composition of Saba Bank fish assemblages reflects the absence of important nursery habitats, as well as the effects of past fishing. The relatively high abundance of large predatory fish (i.e. groupers and sharks), which is generally considered an indicator of good ecosystem health for tropical reef systems, shows that an intact trophic network is still present on Saba Bank.
Subunit and whole molecule specificity of the anti-bovine casein immune response in recent onset psychosis and schizophrenia
Severance, E.G. ; Dickerson, F.B. ; Halling, M. ; Krivogorsky, B. ; Haile, L. ; Yang, S. ; Stallings, C.R. ; Origoni, A.E. ; Bossis, I. ; Xiao, J. ; Dupont, D. ; Haasnoot, W. ; Yolken, R.H. - \ 2010
Schizophrenia Research 118 (2010)1-3. - ISSN 0920-9964 - p. 240 - 247.
cows milk - occupational-status - antibodies - food - association - hypothesis - proteins - humans - blood
Previous studies show increased antibody levels to bovine casein in some individuals with schizophrenia. The immunogenicity of specific domains of bovine casein varies among people with milk sensitivities and thus could vary among different neuropsychiatric disorders. Using ELISAs and immunoblotting, we characterized IgG class antibody specificity to whole bovine casein and to the as, ß, and ¿ subunits in individuals with recent onset psychosis (n = 95), long-term schizophrenia (n = 103), and non-psychiatric controls (n = 65). In both patient groups, we found elevated IgG to casein proteins, particularly to whole casein and the as subunit (p = 0.0001). Odds ratios of casein seroprevalence for recent onset psychosis (age-, gender-, race-, smoking-adjusted) were significant for whole casein (8.13, p = 0.0001), and the as (7.89, p = 0.0001), ß (5.23, p = 0.001) and ¿ (5.70, p = 0.0001) subunits. Odds ratios for long-term schizophrenia were significant for whole casein (7.85, p = 0.0001), and the as (4.78, p = 0.003) and ¿ (4.92, p = 0.004) subunits. Within the recent onset group, odds ratios were particularly significant for a subgroup of people with psychotic disorders that included major depressive disorders (8.22–16.48, p = 0.0001). In a different recent onset subgroup (schizophrenia-spectrum disorders), PANSS scores for negative symptoms were correlated with casein antibody levels for the as and ¿ subunits (p = 0.001–0.01). Immunoblotting patterns also exhibited group specificity, with ¿ predominant in recent onset and as in schizophrenia (Fisher's Exact Test, p = 0.001). The elevated IgG and unique patterns of antibody specificity to bovine casein among diagnostic groups provide a rationale for clinical trials to evaluate efficacies of dietary modifications in individuals with neuropsychiatric diseases.
Immune activation by casein dietary antigens in bipolar disorder
Severance, E.G. ; Dupont, D. ; Dickerson, F.B. ; Stallings, C.R. ; Origoni, A.E. ; Krivogorsky, B. ; Yang, S. ; Haasnoot, W. ; Yolken, R.H. - \ 2010
Bipolar Disorders 12 (2010). - ISSN 1398-5647 - p. 834 - 842.
bovine beta-casein - common variants - cows milk - schizophrenia - hypothesis - antibodies - food - autoimmunity - polymorphism - resistance
Objectives: Inflammation and other immune processes are increasingly linked to psychiatric diseases. Antigenic triggers specific to bipolar disorder are not yet defined. We tested whether antibodies to bovine milk caseins were associated with bipolar disorder, and whether patients recognized different epitopes of the casein protein than control individuals. Methods: Anti-bovine casein immunoglobulin G (IgG) levels were measured with solid-phase immunoassays in 75 individuals with bipolar disorder and 65 controls. Epitope recognition was evaluated in immunoassays by cross neutralization with anti-bovine casein polyclonal antibodies of defined reactivity. Group-specific reactivity and associations with symptom severity scores were detected with age-, gender-, and race-controlled regression models. Results: Individuals with bipolar disorder had significantly elevated anti-casein IgG (t-test, p = 0.001) compared to controls. Casein IgG seropositivity conferred odds ratios of 3.97 for bipolar disorder [n = 75, 95% confidence interval (CI): 1.31–12.08, p = 0.015], 5.26 for the bipolar I subtype (n = 56, 95% CI: 1.66–16.64, p = 0.005), and 3.98 for bipolar disorder with psychosis (n = 54, 95% CI: 1.32–12.00, p = 0.014). Lithium and/or antipsychotic medication did not significantly affect anti-casein IgG levels. Casein IgG measures correlated with severity of manic (R2 = 0.15, 95% CI: 0.05–0.24, p = 0.02) but not depressive symptoms. Unlike controls, sera from individuals with bipolar disorder did not inhibit binding of casein-reactive animal sera (t-test/¿2, p = 0.0001). Conclusions: Anti-casein IgG associations with bipolar I diagnoses, psychotic symptom history, and mania severity scores suggest that casein-related immune activation may relate to the psychosis and mania components of this mood disorder. Case-control differences in epitope recognition implicate disease-related alterations in how the casein molecule is digested and/or how resulting casein-derived structures are rendered immunogenic.
Exposure to the Chinese famine in early life and the risk of hyperglycemia and type 2 diabetes in adulthood.
Li, Y. ; He, Y. ; Qi, L. ; Jaddoe, V.W. ; Feskens, E.J.M. ; Yang, X. ; Ma, G. ; Hu, F.B. - \ 2010
Diabetes 59 (2010)10. - ISSN 0012-1797 - p. 2400 - 2406.
beta-cell mass - in-utero - disease - health - malnutrition - hypothesis - overweight - fetal
OBJECTIVE Early developmental adaptations in response to undernutrition may play an essential role in susceptibility to type 2 diabetes, particularly for those experiencing a "mismatched rich nutritional environment" in later life. We examined the associations of exposure to the Chinese famine (1959-1961) during fetal life and childhood with the risk of hyperglycemia and type 2 diabetes in adulthood. RESEARCH DESIGN AND METHODS We used the data for 7,874 rural adults born between 1954 and 1964 in selected communities from the cross-sectional 2002 China National Nutrition and Health Survey. Hyperglycemia was defined as fasting plasma glucose >= 6.1 mmol/1 and/or 2-h plasma glucose >= mmol/1 and/or a previous clinical diagnosis of type 2 diabetes. RESULTS Prevalences of hyperglycemia among adults in nonexposed, fetal exposed, early-childhood, mid-childhood, and late-childhood exposed cohorts were 2.4%, 5.7%, 3.9%, 3.4%, and 5.9%, respectively. In severely affected famine areas, fetal-exposed subjects had an increased risk of hyperglycemia compared with nonexposed subjects (odds ratio = 3.92; 95% CI: 1.64-9.39; P = 0.002); this difference was not observed in less severely affected famine areas (odds ratio = 0.57; 95% CI: 0.25-1.31; P = 0.185). The odds ratios were significantly different between groups from the severe and less severe famine areas (P for interaction = 0.001). In severely affected famine areas, fetal-exposed subjects who followed an affluent/Western dietary pattern (odds ratios = 7.63; 95% CI: 2.41-24.1; P = 0.0005) or who had a higher economic status in later life experienced a substantially elevated risk of hyperglycemia (odds ratios = 6.20; 95% Cl: 2.08-18.5; P = 0.001). CONCLUSIONS Fetal exposure to the severe Chinese famine increases the risk of hyperglycemia in adulthood. This association appears to be exacerbated by a nutritionally rich environment in later life. Diabetes 59:2400-2406, 2010
Release from soil pathogens plays an important role in the success of invasive Carpobrotus in the Mediterranean
Grunsven, R.H.A. van; Bos, F. ; Ripley, B.S. ; Suehs, C.M. ; Veenendaal, E.M. - \ 2009
South African Journal of Botany 75 (2009)1. - ISSN 0254-6299 - p. 172 - 175.
aizoaceae taxa - enemy release - hybrid vigor - plants - evolution - hybridization - communities - hypothesis - contribute - california
Introduced plant species can become locally dominant and threaten native flora and fauna. This dominance is often thought to be a result of release from specialist enemies in the invaded range, or the evolution of increased competitive ability. Soil borne microorganisms have often been overlooked as enemies in this context, but a less deleterious plant soil interaction in the invaded range could explain local dominance. Two plant species, Carpobrotus edulis and the hybrid Carpobrotus X cf. acinaciformis, are considered major pests in the Mediterranean basin. We tested if release from soil-borne enemies and/or evolution of increased competitive ability could explain this dominance. Comparing biomass production in non-sterile soil with that in sterilized soil, we found that inoculation with rhizosphere soil from the native range reduced biomass production by 32% while inoculation with rhizosphere soil from the invaded range did not have a significant effect on plant biomass. Genotypes from the invaded range, including a hybrid, did not perform better than plants from the native range in sterile soil. Hence evolution of increased competitive ability and hybridization do not seem to play a major role. We conclude that the reduced negative net impact of the soil community in the invaded range may contribute to the success of Carpobrotus species in the Mediterranean basin.
The Resource Curse Revisited and Revised: A Tale of Paradoxes and Red Herrings
Brunnschweiler, C.N. ; Bulte, E.H. - \ 2008
Journal of Environmental Economics and Management 55 (2008)3. - ISSN 0095-0696 - p. 248 - 264.
economic-growth - natural-resources - comparative advantage - political-economy - institutions - abundance - hypothesis - government - regimes - trade
We critically evaluate the empirical basis for the so-called resource curse and find that, despite the topic's popularity in economics and political science research, this apparent paradox may be a red herring. The most commonly used measure of ¿resource abundance¿ can be more usefully interpreted as a proxy for ¿resource dependence¿¿endogenous to underlying structural factors. In multiple estimations that combine resource abundance and dependence, institutional, and constitutional variables, we find that (i) resource abundance, constitutions, and institutions determine resource dependence, (ii) resource dependence does not affect growth, and (iii) resource abundance positively affects growth and institutional quality.
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