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Inter-laboratory comparison of methods to measure androstenone in pork fat
- S. Ampuero Kragten, B. Verkuylen, H. Dahlmans, M. Hortos, J. A. Garcia-Regueiro, E. Dahl, O. Andresen, H. Feitsma, P. K. Mathur, B. Harlizius
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Today, different analytical methods are used by different laboratories to quantify androstenone in fat tissue. This study shows the comparison of methods used routinely in different laboratories for androstenone quantification: Time-resolved fluoroimmunoassay in Norwegian School of Veterinary Science (NSVS; Norway), gas chromatography coupled to mass spectrometry in Co-operative Central Laboratory (CCL; The Netherlands) and in Institut de Recerca i Tecnologia Agroalimentàries (IRTA; Spain), and high-pressure liquid chromatography in Agroscope Liebefeld-Posieux Research Station (ALP; Switzerland). In a first trial, a set of adipose tissue (AT) samples from 53 entire males was sent to CCL, IRTA and NSVS for determination of androstenone concentration. The average androstenone concentration (s.d.) was 2.47 (2.10) μg/g at NSVS, 1.31 (0.98) μg/g at CCL and 0.62 (0.52) μg/g at IRTA. Despite the large differences in absolute values, inter-laboratory correlations were high, ranging from 0.82 to 0.92. A closer look showed differences in the preparation step. Indeed, different matrices were used for the analysis: pure fat at NSVS, melted fat at CCL and AT at IRTA. A second trial was organised in order to circumvent the differences in sample preparation. Back fat samples from 10 entire males were lyophilised at the ALP labortary in Switzerland and were sent to the other laboratories for androstenone concentration measurement. The average concentration (s.d.) of androstenone in the freeze-dried AT samples was 0.87 (0.52), 1.03 (0.55), 0.84 (0.46) and 0.99 (0.67) μg/g at NSVS, CCL, IRTA and ALP, respectively, and the pairwise correlations between laboratories ranged from 0.92 to 0.97. Thus, this study shows the influence of the different sample preparation protocols, leading to major differences in the results, although still allowing high inter-laboratory correlations. The results further highlight the need for method standardisation and inter-laboratory ring tests for the determination of androstenone. This standardisation is especially relevant when deriving thresholds of consumer acceptance, whereas the ranking of animals for breeding purposes will be less affected due to the high correlations between methods.
10 - The carbon economy of lichens
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- By K. Palmqvist, Department of Ecology and Ecology and Environmental Science Umeå University SE-90187 Umeå Sweden, L. Dahlman, Department of Ecology and Environmental Science Umeå University SE-90187 Umeå Sweden, A. Jonsson, Department of Ecology and Environmental Science Umeå University SE-90187 Umeå Sweden, T. H. Nash, School of Life Sciences Arizona State University Box 874501 Tempe, AZ 85287-4501 USA
- Edited by Thomas H. Nash, III, Arizona State University
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- Lichen Biology
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- 05 September 2012
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- 24 June 2008, pp 182-215
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Summary
Growth and survival of photosynthetic carbon autotrophs, such as lichens, are primarily limited by their photosynthetic carbon assimilation minus carbon dioxide (CO2) losses related to growth and maintenance respiration. The absolute, as well as the relative, rates of these two processes will hence determine their capacity to grow. In lichens, both photosynthesis (P) and respiration (R) are strongly constrained by prevailing environmental conditions, particularly water and light. There is also a variation in inherent P and R capacities among species and individuals. Significant progress has been made during the last two decades in understanding how such variations in external conditions and internal capacities affect lichen growth (Boucher and Nash 1990a; Muir et al. 1997; Sundberg et al. 1997, 2001; Hyvärinen and Crittenden 1998b; Palmqvist and Sundberg 2000; Hilmo and Holien 2002; Dahlman and Palmqvist 2003; Hyvärinen et al. 2003; Gaio-Oliveira et al. 2004a, 2006; Gauslaa 2006; Gauslaa et al. 2006b; Palmqvist and Dahlman 2006), including re-establishment of vegetative propagules (Hilmo and Sastad 2001; Hilmo and Ott 2002). This progress has been driven by the development of transplantation techniques in combination with more mechanistically oriented studies, knowledge that has further been used to formulate both conceptual (Palmqvist 2000) and more mechanistically oriented models (Link et al. 1985; Palmqvist and Sundberg 2000; Dahlman and Palmqvist 2003). Such models are useful for the direction of future research towards more explicit hypothesis testing, and could also be adopted to predict how environmental changes may affect particular lichen species, or compare species' abilities to utilize and acclimate to varying environmental conditions.