Sökning: "trophic factor"

Visar resultat 6 - 10 av 62 avhandlingar innehållade orden trophic factor.

1. 6. Dynamics of omnivorous crayfish in freshwater ecosystems

   Författare :Karin Olsson; Biologiska institutionen; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; crayfish; freshwater ecosystems; niche width; growth rate; stable isotope analysis; recruitment; RNA:DNA analysis; Ecology; food availability and quality; trophic position; population dynamics;

   Sammanfattning : In this thesis I examine the dynamics of crayfish in streams and lakes. I have studied the influence of abiotic and biotic factors on abundance, growth, trophic position, niche breadth, and recruitment of crayfish, by conducting field studies, an outdoor channel experiment and timeseries analysis. LÄS MER

3. 7. Complexity and Change in a Simple Food Web : Studies in the Baltic Sea (FAO Area 27.IIId)

   Författare :Henrik Österblom; Sture Hansson; Robert W Furness; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Avian cholera; Bottom-up; Bycatch; Clupea harengus; Ecosystem; Food web; Gadus morhua; Halichoerus grypus; Regime shift; Sprattus sprattus; Top-down; Trophic cascade; Uria aalge; Marine ecology; Marin ekologi;

   Sammanfattning : An influence at one trophic level can result in dynamic impacts also on other components of a food web. These dynamics are known as trophic cascades, and can be both top-down and bottom-up. After a near-collapse of the Baltic cod Gadus morhua stock in the 1980s, its main prey sprat Sprattus sprattus increased dramatically. LÄS MER

4. 8. Effects of temperature and terrestrial carbon on primary production in lake ecosystems

   Författare :Mohammed Hamdan; Jan Karlsson; Pär Byström; Erin R. Hotchkiss; Lars-Anders Hansson; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; lakes; primary production; benthic; pelagic; carbon dioxide limitation; light limitation; nutrient limitation; browning; warming; allochthonous carbon; grazing; trophic cascades;

   Sammanfattning : Climate warming is predicted to affect northern lake food webs in two ways: (1)directly via changes in water temperature and ice conditions, and (2) indirectlyvia changes in catchment characteristics and processes that influence input ofallochthonous coloured dissolved organic matter (cDOM) and nutrients. Input ofcDOM increases carbon dioxide (CO2) availability, causes brownification andreduced light conditions, and may increase nutrient availability especially forpelagic primary producers. LÄS MER

5. 9. Differential effects of voluntary running on hippocampal plasticity in the adult rat brain

   Författare :Andrew Stuart Naylor; Göteborgs universitet; []
   Nyckelord :exercise; hippocampus; stress; progenitor proliferation; neurogenesis; trophic factors; frontal cortex; spatial memory; rat; pCREB; endogenous opioids;

   Sammanfattning : The continuation of neuronal birth from dividing neural stem cells in the dentate gyrus of the hippocampus throughout adulthood is known to play an important role in maintaining normal hippocampal function, such as memory and learning. Negative alterations in the levels of adult neurogenesis have also been linked to several neurodegenerative diseases, including Alzheimer s disease and mood disorders such as depression. LÄS MER

7. 10. Glial cell line-derived neurotrophic factor : expression patterns, neuronal transport, regulation, effects, and receptor dependence

   Författare :Andreas C Tomac; Karolinska Institutet; Karolinska Institutet; []
   Nyckelord :glial cell line-derived neurotrophic factor GDNF ; neurturin NTN ; persephin PSP ; c Ret proto oncogene Ret ; GPI-linked receptors for the GDNF ligand family GFRas ; transforming growth factor-B TGFB ; Parkinson s disease PD ; dopaminergic DA neurons;

   Sammanfattning : Background: The mammalian nervous system depends upon trophic proteins for survival, growth and adult maintenance. These trophic factors have also been considered as potential therapeutic agents for treating human neurodegenerative disorders. LÄS MER