Effects of enrichment on simple aquatic food webs

Simple models, based on Lotka-Volterra types of interactions between predator and prey, predict that enrichment will have a destabilizing effect on populations and that equilibrium population densities will change at the top trophic level and every second level below. We experimentally tested these predictions in three aquatic food web configurations subjected to either high or low nutrient additions. The results were structured by viewing the systems as either food chains or webs and showed that trophic level biomass increased with enrichment, which contradicts food chain theory. However, within each trophic level, food web configuration affected the extent to which different functional groups responded to enrichment. By dividing trophic levels into functional groups, based on vulnerability to consumption, we were able to identify significant effects that were obscured when systems were viewed as food chains. The results support the prediction that invulnerable prey may stabilize trophic-level dynamics by replacing other, more vulnerable prey. Furthermore, the vulnerable prey, such as Daphnia and edible algae, responded as predicted by the paradox of enrichment hypothesis; that is, variability in population density increased with enrichment. Hence, by describing ecosystems as a matrix of food web interactions, and by recognizing the interplay between interspecific competition and predation, a more complete description of the ecosystem function was obtained compared to when species were placed into distinct trophic levels

Vildbin och fragmentering : kunskapssammanställning om situationen för de viktigaste pollinatörerna i det svenska jordbrukslandskapet

Vildbin (humlor och solitära bin) är de viktigaste pollinatörerna. Vildbin är därmed en nyckelgrupp för ekosystemfunktion och hållbar utveckling i jordbrukslandskapet. En allvarlig trend i Västeuropa och Sverige är att förekomst och mångfald av vildbin minskar. Av de knappt 300 svenska vildbiarterna har nära en tredjedel blivit så sällsynta eller gått så kraftigt tillbaka att de rödlistats. Minskningen tillskrivs i första hand degradering (hårdutnyttjande eller igenväxning) och fragmentering (habitatsplittring) av vildbins livsmiljöer, orsakade av förändrad markanvändning i det moderna jordbrukslandskapet. Föreliggande faktasammanställning redovisar fragmenteringens problematik, samt förslag till åtgärder som kan vända den negativa trenden för vildbimångfalden i Sverige. Undersökningar visar att de livsavgörande resurserna som samtidigt måste finnas tillgängliga inom ett vildbis aktionsradie (ca 500 m) är lämpligt boområde och blommande pollen- och nektarväxter. Huvuddelen (70 %) av de svenska solitära vildbiarterna är markbyggande och behöver solexponerad, väldränerad och lättgrävd sand eller mineraljord med sparsamt vegetationstäcke. Även död ved i solbelysta lägen är viktiga bosubstrat för ett antal solitära vildbiarter. Humlor är huvudsakligen markboende och behöver dikesrenar, åkerholmar och kantzoner för bobyggnad. Blommande näringsväxter i tillräckligt stora bestånd är en helt avgörande förutsättning för överlevnad. Flera biarter är starkt specialiserade på en eller några få pollenväxter vars blomning de är beroende av. Speciellt hos humlor, som dock är generalister, är storleken av populationerna beroende av kontinuitet i tillgång på blomresurser i landskapet under vegetationsperioden. Vildbinas rörelser mellan lämpliga habitat underlättas starkt av sammanbindande landskapsstrukturer. Sammanställningen visar att den största hotfaktorn är det alltmer specialiserade, intensiva utnyttjandet av odlingsbar mark. Den tidigare stora resursen av blomrika ogödslade naturliga fodermarker, blommande vall, blomrika kantzoner och blommande trädor i ett mosaikartat landskap är idag kraftigt fragmenterad och har till stor del ersatts av ett totalutnyttjat åkerlandskap utan bärkraftiga blomresurser eller boplatsmöjligheter för vildbin. De tidigare naturliga fodermarkerna har i stor utsträckning endera skogsplanterats eller är alltför hårt betade. Slutsatsen är att det svenska jordbruket måste utvecklas mot en mer mångfaldstolerant markanvändning för att uppnå dagens politiska mål om en hållbar utveckling där de naturliga pollinatörerna förekommer i livskraftiga populationer. Sammanställningen utmynnar i följande rekommendationer för att restaurera jordbrukslandskapet för vildbina och deras pollineringstjänster: A. Ökad blomrikedom 1. Premiera odlingssystem som medför ökade blomresurser: a) Öka areal klövervall och gröngödsling. b) Öka insådd av lågväxande ärtväxter som vitklöver i vall. c) Alternera vallslåttertid eller överhåll viss andel klövervall som får gå i blom så att tillgången på blommande klöver inte bryts på gårdsnivå. d) Minska användning av herbicider. e) Minimera gödsling av vall. f) Inför trädesbruk med insådd av nektar- och pollenrika växter. 2. Förbättra stimulansåtgärder för omläggning till ekologisk odling. 3. Öka arealen och samtidigt blomningstoleransen av bete: a) Tillåt lägre betesintensitet på naturbeten. b) Frångå hårdbete. c) Undvik tidigt bete på särskilt blomrika marker genom stängsling eller rotation. 3 4. Öka bidraget för eftersommarslåtter på blomrik ängsmark så att arealen ökar. B. Ökad boplatsrikedom 1. a) Anlägg bibäddar. b) Bevara exponerade torra slänter och åsar, c) Slänta inte ut sand- och grustag. 2. Röj och sambeta åkerholmar och bryn periodvis så att de behåller mosaikstruktur. 3. Bevara timmerbyggnader, korsvirkeshus, ag och halmtak, samt slå vakt om tillgången på död ved i bryn och på åkerholmar. C. Ökad konnektivitet 1. Inför (sprutfria) blomrika kantzoner i åkermark, vallodling och längs markvägar och skyddszonerna mot vattendrag. 2. Återskapa strukturelement som diken, jordvallar, åkerrenar, åkerholmar och alléer. 3. Följ upp förbud mot herbicidbesprutning på icke odlad mark

The significance of planning and management of the subsurface to achieve sustainable cities

Introduction: The subsurface is the foundation upon which all cities rest. But the subsurface is not only a construction basis which provide physical space for infrastructure and the possibility to create a better surface living environment: the subsurface is a multifunctional natural resource. Apart from physical space, it provides water, energy, materials, habitats for ecosystems, support for surface life, and a repository for cultural heritage and geological archives. Currently, the subsurface is often utilised according to the “first-come-first-served” principle, which hinders possibilities to take strategic decisions on prioritisation and optimisation of competing subsurface uses, as well as fair inter- and intragenerational distribution of limited natural resources. A great disadvantage is the invisibility of the subsurface and consequently a lack of understanding of it as a multifunctional resource: the recently launched concept of geosystem services could help mitigate its underrating. Methods: In order to better acknowledge and lift forward the significance of the subsurface in achieving a sustainable future, the 17 SDGs are scrutinized in relation to the resources of subsurface, and specifically how better planning and management of the subsurface can contribute in achieving the goals. Results: Subsurface planning and management is relevant to at least seven (3, 6, 7, 9, 11, 12, 13) out of seventeen SDGs. Although the subsurface is not explicitly mentioned in the SDGs (except for aquifers), the subsurface can significantly contribute in achieving several of these goals. Conclusions: Sound planning and management of the subsurface can support the achievement of the mapped SDGs in various ways. The subsurface must be recognised as a precious and multifunctional resource which require careful planning and sensitive management in accordance with its potential and its value to society.Grant support: Swedish Research Council Formas (942-2016-50), Swedish Rock Engineering Research Foundation (BeFo 385), Swedish Institute Visby Programme (23887/2017)

Challenging claims in the study of migratory birds and climate change

Recent shifts in phenology in response to climate change are well established but often poorly understood. Many animals integrate climate change across a spatially and temporally dispersed annual life cycle, and effects are modulated by ecological interactions, evolutionary change and endogenous control mechanisms. Here we assess and discuss key statements emerging from the rapidly developing study of changing spring phenology in migratory birds. These well-studied organisms have been instrumental for understanding climate-change effects, but research is developing rapidly and there is a need to attack the big issues rather than risking affirmative science. Although we agree poorly on the support for most claims, agreement regarding the knowledge basis enables consensus regarding broad patterns and likely causes. Empirical data needed for disentangling mechanisms are still scarce, and consequences at a population level and on community composition remain unclear. With increasing knowledge, the overall support (‘consensus view’) for a claim increased and between-researcher variability in support (‘expert opinions') decreased, indicating the importance of assessing and communicating the knowledge basis. A proper integration across biological disciplines seems essential for the field's transition from affirming patterns to understanding mechanisms and making robust predictions regarding future consequences of shifting phenologies

The Measurement of Territorial Differences in the Information Society

Glutamine synthetase (GS, EC 6.3.1.2; also known as γ-glutamyl:ammonia ligase) catalyzes the ATP-dependent condensation of glutamate and ammonia to form glutamine. The enzyme has essential roles in different tissues and species, which have led to its consideration as a drug or an herbicide target. In this article, we describe studies aimed at the discovery of new antimicrobial agents targeting Mycobacterium tuberculosis, the causative pathogen of tuberculosis. A number of distinct classes of GS inhibitors with an IC50 of micromolar value or better were identified via high-throughput screening. A commercially available purine analogue similar to one of the clusters identified (the diketopurines), 1-[(3,4-dichlorophenyl)methyl]-3,7-dimethyl-8-morpholin-4-yl-purine-2,6-dione, was also shown to inhibit the enzyme, with a measured IC50 of 2.5 ± 0.4 μM. Two X-ray structures are presented: one is a complex of the enzyme with the purine analogue alone (2.55-Å resolution), and the other includes the compound together with methionine sulfoximine phosphate, magnesium and phosphate (2.2-Å resolution). The former represents a relaxed, inactive conformation of the enzyme, while the latter is a taut, active one. These structures show that the compound binds at the same position in the nucleotide site, regardless of the conformational state. The ATP-binding site of the human enzyme differs substantially, explaining why it has an ∼ 60-fold lower affinity for this compound than the bacterial GS. As part of this work, we devised a new synthetic procedure for generating l-(SR)-methionine sulfoximine phosphate from l-(SR)-methionine sulfoximine, which will facilitate future investigations of novel GS inhibitors

Subsurface planning: Towards a common understanding of the subsurface as a multifunctional resource

In response to powerful trends in technology, resource and land supply and demand, socioeconomics and geopolitics, cities are likely to increase use of the subsurface in the near future. Indeed, the subsurface and its appropriate use have been put forward as being of crucial importance if we are to achieve resilient and sustainable cities. In recent years, quite apart from being seen primarily as a construction basis to provide physical space for infrastructure and to create a better surface living environment, the subsurface has been recognised as a multifunctional natural resource, one which provides physical space, water, energy, materials, habitats for ecosystems, support for surface life, and a repository for cultural heritage and geological archives. Currently, the subsurface is often utilised according to the “first-come-first-served” principle, which hinders possibilities to take strategic decisions on prioritisation and optimisation of competing subsurface uses, as well as fair inter- and intragenerational distribution of limited natural resources. Taking a broad international perspective, this paper investigates the subsurface as a multifunctional resource from five focal points: (1) what professionals with different backgrounds mean when using different terms related to the subsurface; (2) how professionals describe the subsurface and its multiple resources, functions and services; (3) how planning of subsurface use is supported in policy and regulations; (4) how the subsurface is included in the planning process; and (5) frameworks that can support decision-making on responsible use of the subsurface. The study reveals that the subsurface must be recognised (not only by scientists but also by decision- and policy-makers and other stakeholders) as a precious and multifunctional resource requiring careful planning and sensitive management in accordance with its potential and its value to society. Utilisation of the different subsurface functions to yield services requires careful planning and a framework to support decision-makers in achieving a balance between utilisation and preservation, and between the subsurface functions themselves in the case of outright utilisation. Further, to facilitate the necessary change towards transdisciplinary work settings in the planning process and form a platform for knowledge exchange and capacity building, there is an urgent need for a common language, i.e. mutually understandable terminology, and a common understanding, i.e. an all-inclusive view on the subsurface as a complex multifunctional resource

Higher plasma drug levels in elderly people living with HIV treated with darunavir

Background The proportion of elderly people living with HIV-1 (PLHIV) is rising. In older patients, comorbidities and concomitant medications are more frequent, increasing the risk of potential drug-drug interactions (PDDIs). Data on the pharmacokinetics of ART in individuals aged < 65 years of age are scarce. We compared plasma drug levels of ART, PDDIs, and sideeffects in PLHIV aged < 65 years of age, with controls > 49 years of age. Methods Patients < 65 years of age and controls > 49 years of age, all of whom were on stable treatment with atazanavir (ATV), darunavir (DRV), or efavirenz (EFV) were included cross-sectionally. Plasma drug levels of ART were analyzed, comorbidities, concomitant medication, adherence, and side-effects recorded, and PDDIs analyzed using drug interactions databases. Results Between 2013 and 2015, we included 100 individuals ≥ 65 years of age (study group) and 99 controls (<49 years of age). Steady-state DRV concentrations were significantly higher in the study group than in the control group (p = 0.047). In the ATV group there was a trend towards a significant difference (p = 0.056). No significant differences were found in the EFV arm. The DRV arm had a higher frequency of reported side-effects than the ATV and EFV arms in the study group (36.7% vs. 0% and 23.8% respectively (p = 0.014), with significant differences between DRV vs. ATV, and EFV vs. ATV). Conclusions Higher steady-state plasma levels of DRV and ATV (but not EFV) were found in PLHIV aged < 65 years of age, compared to controls >49 years of age

PROPHECY—a yeast phenome database, update 2006

Connecting genotype to phenotype is fundamental in biomedical research and in our understanding of disease. Phenomics—the large-scale quantitative phenotypic analysis of genotypes on a genome-wide scale—connects automated data generation with the development of novel tools for phenotype data integration, mining and visualization. Our yeast phenomics database PROPHECY is available at . Via phenotyping of 984 heterozygous diploids for all essential genes the genotypes analysed and presented in PROPHECY have been extended and now include all genes in the yeast genome. Further, phenotypic data from gene overexpression of 574 membrane spanning proteins has recently been included. To facilitate the interpretation of quantitative phenotypic data we have developed a new phenotype display option, the Comparative Growth Curve Display, where growth curve differences for a large number of mutants compared with the wild type are easily revealed. In addition, PROPHECY now offers a more informative and intuitive first-sight display of its phenotypic data via its new summary page. We have also extended the arsenal of data analysis tools to include dynamic visualization of phenotypes along individual chromosomes. PROPHECY is an initiative to enhance the growing field of phenome bioinformatics