Remnant grassland habitats as source communities for plant diversification in agricultural landscapes

Lately there has been a shift in Sweden from grazing species-rich semi-natural grasslands towards grazing ex-arable fields in the modern agricultural landscape. These fields normally contain a fraction of the plant species richness compared to semi-natural grasslands. However, small remnant habitats have been suggested as important for plant species diversity and conservation as they may function as refugia for grassland specialists in fragmented and highly modified agricultural landscapes. In this study, we examined whether plant communities on small remnant habitats, i.e. midfield islets, can function as sources for grassland species to disperse out into surrounding grazed ex-fields (former arable fields). We examined species richness and grassland specialists (species favoured by grazing) and their ability to colonize fields after 5 and 11 years of grazing. The fields that had been grazed for a shorter time were fairly species-poor with few grassland specialists. A longer period of grazing had a positive effect on total and small-scale species diversity in both islets and fields. Species composition became more similar with time, and the number of grassland specialists in both habitats increased. We found that grassland specialists dispersed step-wise into the fields, and the number of grassland specialists decreased with distance from the source. Our study suggests that remnant habitats, such as midfield islets, do function as a source community for grassland specialists and enhance diversification of grassland species when grazing is introduced. For long-term conservation of plant species, incorporating small refugia into larger grazing complexes may thus enhance species richness.     

Mechanisms of anti-apoptotic effects of IGF-1 and insulin in free fatty acid-treated RIN-m cells

AIM: To elucidate if the cytoprotective effects of IGF-1 and insulin on free fatty acid-treated pancreatic β cells involve alteration in NF-κB activity.METHODS: Apoptosis was characterized by morphological analysis with invert microscope as well as Hoechst 33342 staining under a fluorescence microscope.Influence of co-incubation with free fatty acid (FFA) and IGF-1 or regular insulin (RI) on NF-κB activity were determined by Western blotting.Impacts of Bay-117082,which is NF-κB inhibitor,on cytoprotective effects of IGF-1 and RI were measured by flow cytometry.RESULTS: Apoptosis measured by flow cytometry was inhibited by IGF-1 and RI and semi-quantitative determination by Western blotting showed co-incubation with FFA and IGF-1 or RI caused more potent activation of NF-κB compared with incubation with FFA solely.Furthermore,flow cytometry showed suppression of NF-κB activity abolished the cytoprotective effects of IGF-1 and RI.CONCLUSION: Our data suggest that anti-apoptotic effects of IGF-1 and regular insulin on FFA-treated RIN-m cells are mediated via NF-κB pathway.