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- Undeland, Ingrid, 1968, et al.
(author)
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Comparison between methods using low-toxicity solvents for the extraction of lipids from herring (Clupea harengus)
- 1998
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In: Food Chemistry. - 0308-8146 .- 1873-7072 .- 0346-718X. ; 61:3, s. 355-365
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Journal article (peer-reviewed)abstract
- Three alkane/alcohol/water-based lipid extraction systems were evaluated to determine which would be the best replacement for the frequently used chloroform/methanol/water system, nowadays known to be very toxic. All the methods were applied to samples of minced herring (Clupea harengus) differing in quality and composition. In addition to comparisons of total lipid yield, the extracted lipids were compared with respect to content of triglycerides, phospholipids, free fatty acids, ?-tocopherol, lipid hydroperoxides and conjugated dienes. The content of phospholipids was found to differ most between the lipids extracted by the four methods. Here, the chloroform/methanol/water system was the most efficient, followed by heptane/ethanol/water/sodium dodecyl sulphate (SDS) and then iso-propanol/hexane. However, by decreasing the level of SDS, the efficiency of the heptane/ethanol/water/SDS system in extracting phospholipids was increased to the same level as that of the chloroform/methanol/water system. This decrease in SDS also resulted in a higher recovery of free fatty acids. The lack of correlation between yields of phospholipids and yields of lipid oxidation products throughout this study was surprising because of the often-described susceptibility of phospholipids to oxidation.
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- Nahalka, J, et al.
(author)
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Elicitation of plumbagin by chitin and its release into the medium in Drosophyllum lusitanicum Link. suspension cultures
- 1998
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In: Biotechnology letters. - 0141-5492 .- 1573-6776. ; 20:9, s. 841-845
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Journal article (peer-reviewed)abstract
- Polysaccharides (chitin/pectin) that are involved in the interactions between plants and microorganisms were applied to the cultured cells of Drosophyllum lusitanicum. In the case of chitin addition, elicitation and crystallization of plumbagin in the medium were observed. N-Acetylchitooligosaccharides smaller than heptamers [(GlcNAc)(n) (n<7)] elicited the biosynthesis of plumbagin but did not increase the hypersensitive response (HR). On the other hand, carboxymethylchitin (DP similar to 200) led to the accumulation of plumbagin in cells and to HR death as well as to the lysis of the cells and release of plumbagin into the medium. The response of cultured cells to the N-Acetylchitosaccharides varied depending on the chemo/physiological conditions of the cells. Addition of pectin (1 g/l) resulted in enhanced HR and decreased biosynthesis of plumbagin.
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| 8. |
- Berndtson, E., et al.
(author)
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A 1-year epidemiological study of campylobacters in 18 Swedish chicken farms
- 1996
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In: Preventive Veterinary Medicine. - : Elsevier. - 0167-5877 .- 1873-1716. ; 26:3-4, s. 167-185
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Journal article (peer-reviewed)abstract
- Broiler chickens are often intestinal carriers of Campylobacter. During processing, Campylobacter may be spread over the carcass. Thus, undercooked chicken meat, or other foods contaminated by raw chicken can act as a source of infection to humans. This study was conducted to identify risk factors for chicken flocks being colonized with Campylobacter. Eighteen chicken farms with altogether 62 chicken compartments were studied for 1 year with visits during each growing period and sampling of chicken caecal contents at slaughter. Four to six subsequent flocks were raised in each compartment during the study. A detailed questionnaire was used to record farm parameters such as building materials, feed and water equipment, hygiene and management routines. Campylobacter prevalence varied between farms, between growing periods within the farms and also during the year, with lowest prevalence during the spring. Campylobacters were isolated from 27% out of 287 flocks. Only two farms were negative at all samplings. Often the flock following a positive flock in a compartment was negative, indicating that normal cleaning and disinfecting routines are sufficient for eliminating the bacteria from the house. Usually only one serotype was found in each positive flock. Campylobacter occurrence increased with the age of the chickens at slaughter, and also with flock size.Univariable chi-square tests were done of the association between possible risk factors and Campylobacter prevalence. Factors associated with higher Campylobacter prevalence in flocks were lack of or diffuse hygiene barriers, increasing flock size, increasing age at slaughter, short vs. long empty periods, wet litter beds, other poultry nearby or staff handling other poultry, flocks divided before slaughter, staff loading to slaughter at several farms and occurrence of mice. Under Swedish conditions, water does not seem to be a source of infection for chickens. Origin and handling of day-old chickens, feed additives, houses and litter were not associated with higher Campylobacter prevalence.
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| 9. |
- Thisted Lambertz, Susanne, et al.
(author)
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A comparison between a PCR method and a conventional culture method for detecting pathogenic Yersinia enterocolitica in food
- 1996
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In: Journal of Applied Bacteriology. - : Blackwell Publishing. - 0021-8847. ; 81:3, s. 303-308
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Journal article (peer-reviewed)abstract
- The aim of this study was to develop a polymerase chain reaction (PCR) method for the detection of pathogenic Yersinia enterocolitica and to compare it with an official culture method (NMKL-117). Primers were selected for nested PCR directed at the attachment invasion locus, ail, on the bacterial chromosome, as well as at a sequence on the pathogenic marker plasmid, termed virulence factor, virF. The final results obtained by the two methods were similar. However, while the conventional method yielded contradictory data for some steps the PCR method provided unambiguous results. Considerable advantages, i.e. higher sensitivity and specificity of the PCR method, compared with the conventional method for detecting pathogenic Y. enterocolitica, were demonstrated in this study.
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| 10. |
- Marklund, S, et al.
(author)
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Molecular basis for the dominant white phenotype in the domestic pig.
- 1998
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In: Genome research. - 1088-9051. ; 8:8, s. 826-33
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Journal article (peer-reviewed)abstract
- The change of phenotypic traits in domestic animals and crops as a response to selective breeding mimics the much slower evolutionary change in natural populations. Here, we describe that the dominant white phenotype in domestic pigs is caused by two mutations in the KIT gene encoding the mast/stem cell growth factor receptor (MGF), one gene duplication associated with a partially dominant phenotype and a splice mutation in one of the copies leading to the fully dominant allele. The splice mutation is a G to A substitution in the first nucleotide of intron 17 and leads to skipping of exon 17. The duplication is most likely a regulatory mutation affecting KIT expression, whereas the splice mutation is expected to cause a receptor with impaired or absent tyrosine kinase activity. Immunocytochemistry showed that this variant form is expressed in 17- to 19-day-old pig embryos. Hundreds of millions of white pigs around the world are assumed to be heterozygous or homozygous for the two mutations. [The EMBL accession numbers for porcine KIT1*0101, KIT1*0202, KIT2*0202, and KIT2*0101 are AJ223228-AJ223231, respectively.]
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