| 1. |
|
|
| 2. |
- Guimarães, Jean R.D., et al.
(författare)
-
Simultaneous radioassays of bacterial production and mercury methylation in the periphyton of a tropical and a temperate wetland
- 2006
-
Ingår i: Journal of Environmental Management. - : Elsevier BV. - 0301-4797 .- 1095-8630. ; 81:2, s. 95-100
-
Tidskriftsartikel (refereegranskat)abstract
- Laboratory radioassays were made to study mercury (Hg) methylation together with bacterial production in the periphyton of two aquatic macrophytes, the submerged Myriophyllum spicatum, from a constructed wetland in Sweden and the floating Eichhornia crassipes, from a eutrophied tropical lake in Brazil. Time course incubations were made by addition of 203HgCl2 and the methylmercury formed was extracted at pre-defined time intervals. Bacterial production (14C-leucine incorporation) was measured at the same time intervals, with plants removed from parallel incubations made with and without addition of cold HgCl2. For E. crassipes, higher methylmercury production was observed at elevated bacterial production, whereas for M. spicatum, the bacterial production was significantly lower, and Hg methylation was below the detection limit. The combined results confirm the importance of microbial processes for Hg methylation, although other factors are known to influence this process in complex ways. The addition of Hg did not significantly influence bacterial production, while the incubation temperatures used (25 and 35 1C) resulted in different methylation rates. Radiotracer techniques for measurements of bacterial production such as 14C-leucine uptake can provide useful insights into the Hg cycle in aquatic environments, and our data suggest that they may be used as a proxy of mercury methylation potentials.
|
|
| 3. |
- Humborg, Christoph, et al.
(författare)
-
Riverine transport of biogenic elements to the Baltic Sea – past and possible future perspectives
- 2007
-
Ingår i: Hydrology and Earth System Sciences. - 1027-5606 .- 1607-7938. ; 11:5, s. 1593-1607
-
Tidskriftsartikel (refereegranskat)abstract
- The paper reviews critical processes for the land-sea fluxes of biogenic elements (C, N, P, Si) in the Baltic Sea catchment and discusses possible future scenarios as a consequence of improved sewage treatment, agricultural practices and increased hydropower demand (for N, P and Si) and of global warming, i.e., changes in hydrological patterns (for C). These most significant drivers will not only change the total amount of nutrient inputs and fluxes of organic and inorganic forms of carbon to the Baltic Sea, their ratio (C:N:P:Si) will alter as well with consequences for phytoplankton species composition in the Baltic Sea. In summary, we propose that N fluxes may increase due to higher livestock densities in those countries recently acceded to the EU, whereas P and Si fluxes may decrease due to an improved sewage treatment in these new EU member states and with further damming and still eutrophic states of many lakes in the entire Baltic Sea catchment. This might eventually decrease cyanobacteria blooms in the Baltic but increase the potential for other nuisance blooms. Dinoflagellates could eventually substitute diatoms that even today grow below their optimal growth conditions due to low Si concentrations in some regions of the Baltic Sea. C fluxes will probably increase from the boreal part of the Baltic Sea catchment due to the expected higher temperatures and heavier rainfall. However, it is not clear whether dissolved organic carbon and alkalinity, which have opposite feedbacks to global warming, will increase in similar amounts, because the spring flow peak will be smoothed out in time due to higher temperatures that cause less snow cover and deeper soil infiltration.
|
|
| 4. |
- Sundbom, Marcus, et al.
(författare)
-
Alteration in human defensin-5 expression following gastric bypass surgery
- 2007
-
Ingår i: Journal of Clinical Pathology. - : BMJ. - 0021-9746 .- 1472-4146. ; 60:9, s. 1029-1034
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Roux-en-Y gastric bypass surgery provides a novel human model to investigate small bowel mucosal innate immunity, in which there is loss of gastric acid-mediated protection against orally-acquired microorganisms. Aim: To study changes in jejunal mucosal immunoreactivity of human defensin (HD)-5,an antimicrobial peptide normally produced by Paneth cells. Methods: Mucosal samples were obtained from 18 female patients ( 24 - 54 years), from the same segment of jejunum during and after gastric bypass surgery. Samples were used for bacterial culture and immunohistochemistry using anti-HD-5 antibody. The number of immunoreactive cells per crypt and villus were determined and expressed as mean (SD). Results: No bacteria were cultured from any of the perioperative jejunal samples but colonies of bacteria normally present in the pharynx were identified during culture of all postoperative jejunal biopsy specimens (1-> 100 colonies). Paneth cell numbers per crypt were unchanged after gastric bypass ( 4.16 (0.71) vs 4.24 (0.78)). However, following surgery, there was an increase in HD-5-positive intermediate cells per crypt (0.25 (0.41) vs 1.12 (0.66), p < 0.01), HD-5 staining enterocytes per crypt ( 0.03 ( 0.09) vs 1.38 ( 1.10), p < 0.01), HD-5 staining material in the crypt lumen (crypt lumens: 5.0% ( 10.9%) vs 68.1% ( 27.9%), p < 0.01) and HD-5 immunoreactivity coating the luminal surface of villus enterocytes ( villi sampled: 15.0% ( 31.0%) vs 67.5% ( 42.0%), p < 0.01). Conclusions: Bacteria normally resident in the pharynx were present in the proximal jejunal mucosa following Roux-en-Y gastric bypass surgery. After gastric bypass, there was increased secretion of HD-5 and an increase in HD-5 expressing intermediate cells and enterocytes in the crypt. The increase in HD-5 expression in the jejunal mucosa following gastric bypass surgery is likely to be secondary to exposure to orally-acquired microorganisms.
|
|
| 5. |
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
|
|
| 9. |
|
|
| 10. |
|
|
