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- Cornelissen, Johannes H C, et al.
(författare)
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Global negative vegetation feedback to climate warming responses of leaf litter decomposition rates in cold biomes
- 2007
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Ingår i: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 10:7, s. 619-627
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Tidskriftsartikel (refereegranskat)abstract
- Whether climate change will turn cold biomes from large long-term carbon sinks into sources is hotly debated because of the great potential for ecosystem-mediated feedbacks to global climate. Critical are the direction, magnitude and generality of climate responses of plant litter decomposition. Here, we present the first quantitative analysis of the major climate-change-related drivers of litter decomposition rates in cold northern biomes worldwide.Leaf litters collected from the predominant species in 33 global change manipulation experiments in circum-arctic-alpine ecosystems were incubated simultaneously in two contrasting arctic life zones. We demonstrate that longer-term, large-scale changes to leaf litter decomposition will be driven primarily by both direct warming effects and concomitant shifts in plant growth form composition, with a much smaller role for changes in litter quality within species. Specifically, the ongoing warming-induced expansion of shrubs with recalcitrant leaf litter across cold biomes would constitute a negative feedback to global warming. Depending on the strength of other (previously reported) positive feedbacks of shrub expansion on soil carbon turnover, this may partly counteract direct warming enhancement of litter decomposition.
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- Engelmark, Malin T., et al.
(författare)
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Identification of susceptibility loci for cervical carcinoma by genome scan of affected sib-pairs
- 2006
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Ingår i: Human Molecular Genetics. - : Oxford University Press (OUP). - 0964-6906 .- 1460-2083. ; 15:22, s. 3351-3360
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Tidskriftsartikel (refereegranskat)abstract
- Cervical cancer is caused by a combination of environmental and genetic risk factors. Infection by oncogenic types of human papillomavirus is recognized as the major environmental risk factor and epidemiological studies indicate that host genetic factors predispose to disease development. A number of genetic susceptibility factors have been proposed, but with exception of the human leukocyte antigen CHLA, class II, have not shown consistent results among studies. We have performed the first genomewide linkage scan using 278 affected sib-pairs to identify loci involved in susceptibility to cervical cancer. A two-step qualitative non-parametric linkage analysis using 387 microsatellites with an average spacing of 10.5 cM revealed excess allelic sharing at nine regions on eight chromosomes. These regions were further analysed with 125 markers to increase the map density to 1.28 cM. Nominal significant linkage was found for three of the nine loci [9q32 (maximum lod-score, MLS) =1.95, P < 0.002), 12q24 (MLS=1.25, P < 0.015) and 16q24 (MLS=1.35, P < 0.012)]. These three regions have previously been connected to human cancers that share characteristics with cervical carcinoma, such as esophageal cancer and Hodgkin's lymphoma. A number of candidate genes involved in defence against viral infections, immune response and tumour suppression are found in these regions. One such gene is the thymic stromal co-transporter (TSCOT). Analyses of TSCOT single nucleotide polymorphisms further strengthen the linkage to this region (MLS=2.40, P < 0.001). We propose that the 9q32 region contains susceptibility locus for cervical cancer and that TSCOT is a candidate gene potentially involved in the genetic predisposition to this disease.
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- Grdic, D, et al.
(författare)
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Splenic marginal zone dendritic cells mediate the cholera toxin adjuvant effect : Dependence on the ADP-ribosyltransferase activity of the holotoxin
- 2005
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Ingår i: Journal of Immunology. - 0022-1767 .- 1550-6606. ; 175:8, s. 5192-5202
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Tidskriftsartikel (refereegranskat)abstract
- The in vivo mechanisms of action of most vaccine adjuvants are poorly understood. In this study, we present data in mice that reveal a series of critical interactions between the cholera toxin (CT) adjuvant and the dendritic cells (DC) of the splenic marginal zone (MZ) that lead to effective priming of an immune response. For the first time, we have followed adjuvant targeting of MZ DC in vivo. We used CT-conjugated OVA and found that the Ag selectively accumulated in MZ DC following i.v. injections. The uptake of Ag into DC was GM1 ganglioside receptor dependent and mediated by the B subunit of CT (CTB). The targeted MZ DC were quite unique in their phenotype: CD11c(+), CD8 alpha(-), CD11b(-), B220(-), and expressing intermediate or low levels of MHC class II and DEC205. Whereas CTB only delivered the Ag to MZ DC, the ADP-ribosyltransferase activity of CT was required for the maturation and migration of DC to the T cell zone, where these cells distinctly up-regulated CD86, but not CD80. This interaction appeared to instruct Ag-specific CD4(+) T cells to move into the B cell follicle and strongly support germinal center formations. These events may explain why CT-conjugated Ag is substantially more immunogenic than Ag admixed with soluble CT and why CTB-conjugated Ag can tolerize immune responses when given orally or at other mucosal sites.
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- Ljungvall, K, et al.
(författare)
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Early post-natal exposure to low dose oral di(2ethylhexyl) phthalate affects the peripheral LH-concentration in plasma, but does not affect mating behavior in the post-pubertal boar
- 2006
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Ingår i: Reproductive Toxicology. - : Elsevier. - 0890-6238 .- 1873-1708. ; 21:2, s. 160-166
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Tidskriftsartikel (refereegranskat)abstract
- In a split-litter design experiment, boars were exposed orally three times weekly to 300 mg/kg of di(2-ethylhexyl) phthalate (DEHP) between 3 and 7 weeks of age. Post-puberty, i.e. at 6 months of age the effects on endocrinology and mating behavior were examined. The response to stimulation with a synthetic GnRH-analogue at 9 months of age resulted initially in lower concentration of LH in the exposed animals, compared to the control animals. We did not find any effects of DEHP on the mating behavior. Also, the effects of DEHP during the treatment period on the plasma concentrations of testosterone, oestradiol and LH were examined. During the exposure period there was a transient decrease in plasma concentrations of LH in the control group, which did not occur in the boars exposed to DEHR The data suggest that DEHP in low repeated oral doses causes lasting effects on the hypothalamus-pituitary-gonadal axis. (c) 2005 Elsevier Inc. All rights reserved.
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