| 1. |
- Magnusson, Roger, et al.
(författare)
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Effect of Gasoline and Lubricant on Emissions and Mutagenicity of Particles and Semivolatiles in Chain Saw Exhaust
- 2000
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Ingår i: Environmental Science & Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 34:14, s. 2918-24
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Tidskriftsartikel (refereegranskat)abstract
- The exhaust from a two-stroke chain saw engine was characterized using two different types of gasoline, aliphatic gasoline and conventional lead-free gasoline, in combination with four lubricants differing in mineral oil, polyolester, and polyisobutylene (PIB) content. This characterization was focused on emissions of polycyclic aromatic hydrocarbons (PAH) and mutagenicity testing using Ames Salmonella assay. In addition, exhaust emissions of carbon monoxide (CO), nitrogen oxides (NOx), aldehydes, and hydrocarbons (HC) were measured. The two-stroke engine was tested in a test bench, and particulate, semivolatile, and gaseous exhaust components were sampled using a dilution tunnel. Much less PAH were emitted when using aliphatic gasoline due to a much lower gasoline content of PAH and aromatics than the conventional gasoline. Also about half the NOx emissions, up to 50% higher formaldehyde and acetaldehyde emissions, and 10% higher total HC emissions were observed for the aliphatic gasoline. The influence of lubricant on the studied exhaust emissions was found to be of minor importance. In terms of mutagenicity, significant effects were seen for six of the eight gasoline/lubricant combinations, and the highest effects were observed without a metabolizing system. Generally, the conventional gasoline gave higher effects than did the aliphatic gasoline. A difference between lubricants was also seen, especially in combination with gasoline A; however, the interpretation of mutagenic effects of the lubricants was not straightforward. Overall, one synthetic ester-based lubricant and one mineral oil-based lubricant gave the highest mutagenicity.
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| 2. |
- Andersson, Agneta, et al.
(författare)
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Fatty acid profile of skeletal muscle phospholipids in trained and untrained young men
- 2000
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Ingår i: American Journal of Physiology. Endocrinology and Metabolism. - 0193-1849 .- 1522-1555. ; 279:4, s. E744-E751
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Tidskriftsartikel (refereegranskat)abstract
- Endurance trained (n = 14) and untrained young men (n = 15) were compared regarding the fatty acid profile of the vastus lateralis muscle after 8 wk on diets with a similar fatty acid composition. The skeletal muscle phospholipids in the trained group contained lower proportions of palmitic acid (16:0) (-12.4%, P < 0.001) and di-homo-gamma-linolenic acid [20:3(n-6)] (-15.3%, P = 0.018), a lower n-6-to-n-3 ratio (-42.0%, P = 0.015), higher proportions of stearic acid (18:0) (+9.8%, P = 0.004) and sum of n-3 polyunsaturated fatty acids (+33.8%, P = 0.009), and a higher ratio between 20:4(n-6) to 20:3(n-6) (+18.4%, P = 0.006) compared with those in the untrained group. The group differences in 16:0, 20:3(n-6), 18:0/16:0, and 20:4(n-6)/20:3(n-6) were independent of fiber-type distribution. The trained group also showed a lower proportion of 16:0 (-7.9%, P < 0.001) in skeletal muscle triglycerides irrespective of fiber type. In conclusion, the fatty acid profile of the skeletal muscle differed between trained and untrained individuals, although the dietary fatty acid composition was similar. This difference was not explained by different fiber-type distribution alone but appears to be a direct consequence of changes in fatty acid metabolism due to the higher level of physical activity.
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| 3. |
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| 4. |
- Andersson, Jan O, 1971-, et al.
(författare)
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A cyanobacterial gene in nonphotosynthetic protists : an early chloroplast acquisition in eukaryotes?
- 2002
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Ingår i: Current Biology. - 0960-9822 .- 1879-0445. ; 12:2, s. 115-119
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Tidskriftsartikel (refereegranskat)abstract
- Since the incorporation of mitochondria and chloroplasts (plastids) into the eukaryotic cell by endosymbiosis, genes have been transferred from the organellar genomes to the nucleus of the host, via an ongoing process known as endosymbiotic gene transfer. Accordingly, in photosynthetic eukaryotes, nuclear genes with cyanobacterial affinity are believed to have originated from endosymbiotic gene transfer from chloroplasts. Analysis of the Arabidopsis thaliana genome has shown that a significant fraction (2%-9%) of the nuclear genes have such an endosymbiotic origin. Recently, it was argued that 6-phosphogluconate dehydrogenase (gnd)-the second enzyme in the oxidative pentose phosphate pathway-was one such example. Here we show that gnd genes with cyanobacterial affinity also are present in several nonphotosynthetic protistan lineages, such as Heterolobosea, Apicomplexa, and parasitic Heterokonta. Current data cannot definitively resolve whether these groups acquired the gnd gene by primary and/or secondary endosymbiosis or via an independent lateral gene transfer event. Nevertheless, our data suggest that chloroplasts were introduced into eukaryotes much earlier than previously thought and that several major groups of heterotrophic eukaryotes have secondarily lost photosynthetic plastids.
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| 5. |
- Andersson, Jan O., et al.
(författare)
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Evolution of glutamate dehydrogenase genes : evidence for lateral gene transfer within and between prokaryotes and eukaryotes
- 2003
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Ingår i: BMC Evolutionary Biology. - : BioMed Central. - 1471-2148. ; 3, s. 14-
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Tidskriftsartikel (refereegranskat)abstract
- Background Lateral gene transfer can introduce genes with novel functions into genomes or replace genes with functionally similar orthologs or paralogs. Here we present a study of the occurrence of the latter gene replacement phenomenon in the four gene families encoding different classes of glutamate dehydrogenase (GDH), to evaluate and compare the patterns and rates of lateral gene transfer (LGT) in prokaryotes and eukaryotes. Results We extend the taxon sampling of gdh genes with nine new eukaryotic sequences and examine the phylogenetic distribution pattern of the various GDH classes in combination with maximum likelihood phylogenetic analyses. The distribution pattern analyses indicate that LGT has played a significant role in the evolution of the four gdh gene families. Indeed, a number of gene transfer events are identified by phylogenetic analyses, including numerous prokaryotic intra-domain transfers, some prokaryotic inter-domain transfers and several inter-domain transfers between prokaryotes and microbial eukaryotes (protists). Conclusion LGT has apparently affected eukaryotes and prokaryotes to a similar extent within the gdh gene families. In the absence of indications that the evolution of the gdh gene families is radically different from other families, these results suggest that gene transfer might be an important evolutionary mechanism in microbial eukaryote genome evolution.
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| 6. |
- Andersson, Jan O, 1971-, et al.
(författare)
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Evolutionary analyses of the small subunit of glutamate synthase : gene order conservation, gene fusions, and prokaryote-to-eukaryote lateral gene transfers
- 2002
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Ingår i: Eukaryotic Cell. - 1535-9778 .- 1535-9786. ; 1:2, s. 304-310
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Tidskriftsartikel (refereegranskat)abstract
- Lateral gene transfer has been identified as an important mode of genome evolution within prokaryotes. Except for the special case of gene transfer from organelle genomes to the eukaryotic nucleus, only a few cases of lateral gene transfer involving eukaryotes have been described. Here we present phylogenetic and gene order analyses on the small subunit of glutamate synthase (encoded by gltD) and its homologues, including the large subunit of sulfide dehydrogenase (encoded by sudA). The scattered distribution of the sudA and sudB gene pair and the phylogenetic analysis strongly suggest that lateral gene transfer was involved in the propagation of the genes in the three domains of life. One of these transfers most likely occurred between a prokaryote and an ancestor of diplomonad protists. Furthermore, phylogenetic analyses indicate that the gene for the small subunit of glutamate synthase was transferred from a low-GC gram-positive bacterium to a common ancestor of animals, fungi, and plants. Interestingly, in both examples, the eukaryotes encode a single gene that corresponds to a conserved operon structure in prokaryotes. Our analyses, together with several recent publications, show that lateral gene transfers from prokaryotes to unicellular eukaryotes occur with appreciable frequency. In the case of the genes for sulfide dehydrogenase, the transfer affected only a limited group of eukaryotes--the diplomonads--while the transfer of the glutamate synthase gene probably happened earlier in evolution and affected a wider range of eukaryotes.
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| 7. |
- Andersson, Jan O, 1971-, et al.
(författare)
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Phylogenetic analyses of diplomonad genes reveal frequent lateral gene transfers affecting eukaryotes
- 2003
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Ingår i: Current Biology. - 0960-9822 .- 1879-0445. ; 13:2, s. 94-104
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Lateral gene transfer (LGT) is an important evolutionary mechanism among prokaryotes. The situation in eukaryotes is less clear; the human genome sequence failed to give strong support for any recent transfers from prokaryotes to vertebrates, yet a number of LGTs from prokaryotes to protists (unicellular eukaryotes) have been documented. Here, we perform a systematic analysis to investigate the impact of LGT on the evolution of diplomonads, a group of anaerobic protists.RESULTS: Phylogenetic analyses of 15 genes present in the genome of the Atlantic Salmon parasite Spironucleus barkhanus and/or the intestinal parasite Giardia lamblia show that most of these genes originated via LGT. Half of the genes are putatively involved in processes related to an anaerobic lifestyle, and this finding suggests that a common ancestor, which most probably was aerobic, of Spironucleus and Giardia adapted to an anaerobic environment in part by acquiring genes via LGT from prokaryotes. The sources of the transferred diplomonad genes are found among all three domains of life, including other eukaryotes. Many of the phylogenetic reconstructions show eukaryotes emerging in several distinct regions of the tree, strongly suggesting that LGT not only involved diplomonads, but also involved other eukaryotic groups.CONCLUSIONS: Our study shows that LGT is a significant evolutionary mechanism among diplomonads in particular and protists in general. These findings provide insights into the evolution of biochemical pathways in early eukaryote evolution and have important implications for studies of eukaryotic genome evolution and organismal relationships. Furthermore, "fusion" hypotheses for the origin of eukaryotes need to be rigorously reexamined in the light of these results.
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| 8. |
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| 9. |
- Andersson, Roger, 1967-, et al.
(författare)
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An asymmetric dialysis tube as an integrated part of a pressure-monitoring sensor
- 2001
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Ingår i: Technology and Health Care. - 0928-7329 .- 1878-7401. ; 9:5, s. 417-425
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Tidskriftsartikel (refereegranskat)abstract
- A sensor has been designed consisting of a tube holder with a force transducer and a tube with a modified cross-section. The holder has a lid that encloses the tube. By having a stiff holder and a compliant tube, the idea is that the intraluminal pressure in the tube can be obtained from the measured force. The method is intended for non-invasive pressure measurements in blood or dialysate tubes.We have used a tube cross-sectional geometry where the outer surface is elliptic and the inner surface is circular with a relation of 2:1 between the thinnest and thickest tube sides. The pressure transducer system shows a linear relationship between the applied pressure and the sensor output (r = 0.999). Within the temperature range, 32°–36°C, which corresponds to the blood and dialysate temperatures, the sensor accuracy is within ±0.8 kPa (±6 mm Hg). This indicates that the sensor should be clinically useful during dialysis and similar applications.
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| 10. |
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