| 1. |
- Berndtson, Eva, et al.
(författare)
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Campylobacter incidence on a chicken farm and the spread of Campylobacter during the slaughter process
- 1996
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Ingår i: International Journal of Food Microbiology. - : Elsevier. - 0168-1605 .- 1879-3460. ; 32:1-2, s. 35-47
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Tidskriftsartikel (refereegranskat)abstract
- To get a better understanding of the epidemiology of Campylobacter, a chicken farm was studied for 16 weeks with samplings in each flock weekly from input until the flock became colonized with Campylobacter or slaughtered. Samples were taken from fresh droppings and from drinkers during the rearing period, as well as from the environment in empty houses. The spread of Campylobacter during the slaughter process was also surveyed. No Campylobacter was found in samples from newly-hatched ol one-week-old chickens or their drinkers. All Hocks but one were colonized at two to five weeks of age. All Campylobacter isolates belonged to the same sero- and biotype; C. jejuni Penner 2. The spread of Campylobacter in the flock was rapid and usually all samples were positive once colonization had been proven. C. jejuni was isolated from flies in ante-rooms as well as from air in chicken units ill houses with positive chicken flocks. Samples were taken at slaughter when some of the Campylobacter positive Hocks from the farm were slaughtered. Campylobacter were isolated from all sampled equipment along the processing line, from the chicken transport crates to the chillers, as well as from the air.
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| 2. |
- Halpin, Christina G., et al.
(författare)
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Being conspicuous and defended : selective benefits for the individual
- 2008
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Ingår i: Behavioral Ecology. - : Oxford University Press. - 1045-2249 .- 1465-7279. ; 19:5, s. 1012-1017
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Tidskriftsartikel (refereegranskat)abstract
- Aposematic insects conspicuously advertise their unprofitability to potential predators. However, when these prey initially evolved, they were likely to have been rare and presumably at a greater risk of being detected and killed by naive predators. Both kin and individual selection theories have been used in attempts to explain this apparent paradox, with much of the empirical research supporting kin selection–based theories. Here, we experimentally test how chemical defence levels in prey and avian color biases influence the probability of a rare conspicuous morph having an initial survival advantage. We used newly hatched domestic chicks (Gallus gallus domesticus) foraging on green and purple prey, on a green or purple background, to model the evolutionary scenario of a rare conspicuous morph arising in a population of already defended cryptic prey. Defended prey were produced by spraying them with quinine solution, which the birds readily detect and can learn to avoid. Although attack rates were initially similar for both defended prey types, the chicks only learned to avoid defended prey when they were conspicuous, not when they were cryptic. In addition, defended conspicuous prey were more likely to be rejected on attack than defended cryptic prey, even when first encountered by a predator. These data suggest that there could be a selective advantage for a rare conspicuous morph to arise in a population of cryptic defended prey due to increased avoidance learning and taste-rejection in naive predators. Our findings also suggest that being a non-preferred color and/or highly defended will increase the probability of this evolutionary scenario.
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| 3. |
- Engwall, Magnus, 1965-, et al.
(författare)
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Cytochrome P450IA induction by a coplanar PCB, a PAH mixture, and PCB-contaminated sediment extracts following microinjection of rainbow trout sac-fry
- 1994
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Ingår i: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 30:4, s. 311-324
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Tidskriftsartikel (refereegranskat)abstract
- The 7-ethoxyresorufin-O-deethylase (EROD)-inducing potencies of a coplanar polychlorinated biphenyl (PCB) (3,3',4,3',5-pentachlorobiphenyl, IUPAC No. 126), a mixture of five polycyclic aromatic hydrocarbons (benzo(k)fluoranthene, benz(a)anthracene, benzo(a)pyrene, indeno(1,2,3-cd)pyrene and chrysene), and lipophilic compounds extracted from the sediments in a PCB-contaminated lake and from sediments in lakes up- and downstream, were studied in rainbow trout sac-fry in a 43-day study. The compounds/extracts were injected into the yolk sacs of newly hatched sac-fry and hepatic EROD activities and mortality rates were measured at various times after the injections. Five livers from each group were also examined by transmission electron microscopy. All the compounds/extracts induced hepatic EROD activities in the sac-fry. Ten days after injection the EROD activity caused by PCB No. 126 (1.3 ng per embryo) was 40-fold compared to the control activity. This was the highest induction rate observed in the experiment. For the sediment extracts, the highest induction rates were observed at the first sampling occasion, which for these groups was on day 24. The extract from the Lake Jarnsjon sediment was more potent as an EROD inducer than the extracts of sediments from the lakes up- and downstream from Lake Jarnsjon. None of the sediment extracts caused any significant mortality. In sac-fry injected with the PAH mixture, EROD was only slightly induced. The highest dose of PAHs (10 mu g per embryo) caused about 90% mortality by 24 days after injection. When the livers were examined by transmission electron microscopy, morphological alterations (e.g. hepatocyte degeneration and hypertrophy) were seen in the groups injected with Lake Jarnsjon sediment extract, PCB No. 126 and the highest dose of the PAH mixture (10 mu g per embryo).
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