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Visar resultat 1 - 5 av 83 avhandlingar som matchar ovanstående sökkriterier.
1. Mixture toxicity of pesticides and biological effects in agricultural streams : field and laboratory studies
Sammanfattning : The main objective of this thesis was to examine pesticide mixture toxicity and its effects on aquatic biota in agricultural streams. This was accomplished by (1) calculating the ΣTUs for algae and Daphnia magna and a pesticide toxicity index (PTI) based on water quality standards (WQS) for long-term monitoring data (2002-2010), (2) by performing algal inhibition tests with Pseudokirchneriella subcapitata, using both collected in situ water samples and reconstituted water spiked with field-observed pesticide mixtures, and (3) by studying seasonal changes in macroinvertebrate and diatom communities during 2008 in four agricultural streams and determine a set of community-based metrics such as species richness, diversity, ASPT, SPEAR and IPS. LÄS MER
2. Biological diversity values in semi-natural grasslands : indicators, landscape context and restoration
Sammanfattning : Semi-natural grasslands, which are a declining and fragmented habitat in Europe, contain a high biodiversity, and are therefore of interest to conservation. This thesis examines how plant diversity is influenced by the landscape context, and how plant and fungal diversity can be targeted by practical conservation using indicator species and congruence between species groups. LÄS MER
3. Brain Aromatase in the guppy, Poecilia reticulata : Distribution, control and role in behaviour
Sammanfattning : Oestrogens are produced by aromatisation of androgens by the aromatase enzyme. In the vertebrate brain this synthesis has vital functions in nerve protection, cell proliferation and nerve development during injury respectively brain development. LÄS MER
4. Biodiversity in fragmented boreal forests : assessing the past, the present and the future
Sammanfattning : The aims of this thesis are to (1) analyze the predictability (indicators) of plant and fungal species diversity in old-growth forests, and (2) assess the history and biodiversity of woodland key habitats (WKHs) and their potential to maintain species diversity in fragmented boreal forest landscapes. Predictability was explored in Granlandet nature reserve, an unexploited landscape composed of discrete old-growth Picea forest patches of varying size isolated by wetland, reflecting conditions of insular biota at stochastic equilibrium. LÄS MER
5. Protein synthesis in vitro in skeletal muscle as an indicator of feeding conditions
Sammanfattning : The activity of protein synthesis in vitro was determined using ribosomes isolated from rats, domestic animals and fish. The activity of rat skeletal muscle ribosomes was influenced by small differences in the nutritional quality of dietary proteins. LÄS MER
