| 1. |
- Svensson, Per Anders, 1959, et al.
(författare)
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Identification of genes predominantly expressed in human macrophages
- 2004
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Ingår i: Atherosclerosis. - : Elsevier BV. ; 177, s. 287-290
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Tidskriftsartikel (refereegranskat)abstract
- Identification of cell and tissue specific genes may provide novel insights to signaling systems and functions. Macrophages play a key role in many diseases including atherosclerosis. Using DNA microarrays we compared the expression of approximately 10,000 genes in 56 human tissues and identified 23 genes with predominant expression in macrophages. The identified genes include both genes known to be macrophage specific and genes previously not well described in this cell type. Tissue distribution of two genes, liver X receptor (LXR) alpha and interleukin-1 receptor antagonist (IL1RN), was verified by real-time RT-PCR. We conclude that comparison of expression profiles from a large number of tissues can be used to identify genes that are predominantly expressed in certain tissues. Identification of novel macrophage specific genes may increase our understanding of the role of this cell in different diseases.
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| 2. |
- Nyström, Per, et al.
(författare)
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The influence of multiple introduced predators on a littoral pond community
- 2001
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Ingår i: Ecology. - 0012-9658. ; 82:4, s. 1023-1039
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Tidskriftsartikel (refereegranskat)abstract
- In a replicated field experiment we studied the effects of natural densities of two exotic consumers, the predatory and herbivorous signal crayfish (Pacifastacus leniusculus) and the predatory rainbow trout (Oncorhynchus mykiss), on multiple trophic levels of a pond community. The goals were to: (1) determine the individual and combined effects of predators on macroinvertebrates, macrophytes, and periphytic algae; (2) evaluate the strength of direct and indirect interactions in a food web influenced by omnivores; and (3) evaluate the relative importance of direct and indirect predator effects on mortality and growth of a native frog species, Rana temporaria. The experiment showed that both signal crayfish and rainbow trout had strong effects on multitrophic levels of a littoral pond community, through direct consumption and indirect effects on lower trophic levels. Crayfish had weak but significant negative effects on the biomass of predatory invertebrates and greatly reduced the biomass of snails, the most abundant invertebrate grazers. Although the number of active herbivorous tadpoles tended to be higher in crayfish cages relative to control cages, the proportion of surviving froglets was lower in crayfish cages than in control cages, possibly due to crayfish predation on injured tadpoles. The size of surviving froglets did not differ from controls, but tadpoles in crayfish cages often suffered tail injuries. Macrophyte coverage decreased as a result of crayfish consumption and nonconsumptive fragmentation. However, the biomass of periphyton increased in crayfish cages relative to controls, probably due to reduced grazing from snails. In contrast, trout had strong negative effects on the biomass of both predatory invertebrates and insect grazers, whereas trout had less effect on snail biomass than did crayfish. Also, in contrast to crayfish cages, the number of active tadpoles in trout cages was lower than in controls, probably due to a combination of trout predation and trout-induced reduced tadpole activity. Trout had a strong negative impact on froglet survival, and froglets in trout cages metamorphosed at a smaller size and had reduced growth rates compared to froglets in crayfish and control cages. As with crayfish, the biomass of periphyton increased in trout cages relative to controls, which may be due to a combination of both density and trait-mediated trout effects on tadpole grazing. In treatments with multiple predators the effects of crayfish and trout on caged communities were independent, and there were few interactions. Mostly effects of combined predators reflected those in single predator cages. Our results demonstrate that noninteracting, introduced multiple predators can have strong direct and indirect effects on multiple trophic levels in pond communities. Trophic cascades may develop in aquatic food webs even with omnivores such as crayfish, and in complex habitats with trout. These strong indirect effects are mediated through both predation on important grazers (i.e., the crayfish-snail-periphyton link) and a combination of density and behavioral responses of grazers to predators (i.e., the trout-tadpole-periphyton link). When two noninteracting predators have strong but different effects on prey survival or activity, their combined effects on intermediate trophic levels reflect responses to the more dangerous predator.
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| 3. |
- Svensson, Per-Arne, 1969, et al.
(författare)
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Copper induces the expression of cholesterogenic genes in human macrophages.
- 2003
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Ingår i: Atherosclerosis. - 0021-9150. ; 169:1, s. 71-6
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Tidskriftsartikel (refereegranskat)abstract
- Accumulation of lipids and cholesterol by macrophages and subsequent transformation into foam cells are key features in development of atherosclerosis. Serum copper concentrations have been shown to be associated with cardiovascular disease. However, the mechanism behind the proatherogenic effect of copper is not clear. We used DNA microarrays to define the changes in gene expression profile in response to copper exposure of human macrophages. Expression monitoring by DNA microarray revealed 91 genes that were regulated. Copper increased the expression of seven cholesterogenic genes (3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) synthase, IPP isomerase, squalene synthase, squalene epoxidase, methyl sterol oxidase, H105e3 mRNA and sterol-C5-desaturase) and low-density lipoprotein receptor (LDL-R), and decreased the expression of CD36 and lipid binding proteins. The expression of LDL-R and HMG CoA reductase was also investigated using real time PCR. The expression of both of these genes was increased after copper treatment of macrophages (P<0.01 and P<0.01, respectively). We conclude that copper activates cholesterogenic genes in macrophages, which may provide a mechanism for the association between copper and atherosclerosis. The effect of copper on cholesterogenic genes may also have implications for liver steatosis in early stages of Wilson's disease.
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