| 论文摘要： |
The topmouth culter (Culter alburnus Basilewsky, 1855) is a freshwater carnivorous fish of high nutritional value and widely distributed in lakes and reservoirs of China. In order to evaluate the fatty acid profiles in relation to habitat characteristics and to elucidate the main composition predictors, C.alburnus were collected from five lakes (Xingkai- LXk, Hongze- LHz, Kuilei- LKl, Chidong- LCd and Dongting- LDt) in China, ranging in latitudes from 28 degrees 30 to 44 degrees 44N and altitudes from 4 to 64m. Ten fish from each lake ranging in total lengths from 414.2 to 423.9mm were sampled between May to June in 2013 and 2014. A total of 23 fatty acids were identified using gas chromatography. Fatty acids that predominated in muscle samples of the fish were 16:0, 18:0, 16:1n-7, 18:1n-9, 20:5n-3, 22:6n-3 and 20:4n-6. Important differences in the fatty acid profiles of fish from high and low latitude lakes were discernible in that the two high latitudinal lakes (LXk and LHz) had significantly higher (p<.05) ratios of n-3 to n-6 fatty acids and levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), than those fishes in the low latitudinal lakes (LKl, LCd and LDt); these observations were confirmed by a principal component analysis. Therefore, it appears that multivariate analysis enables to distinguish fish from different lakes based on their characteristic fatty acid signatures; this would make a contribution to fish product traceability. The percentages of total saturated fatty acids increased significantly with increasing ambient temperature, and lakes at lower latitudes had higher levels of 17:0, 18:0, 18:2n-6, 20:3n-6 and lower levels of 16:1n-7 and 18:1n-9. Theoretical information criteria showed that the percentage of total saturated fatty acids varied more with temperature than with latitude and that this temperature-dependent variation is nonlinear. Variation partitioning shows that most of the geographical variations are not only due to the nonlinear effects of temperature but also to the independent effects of the lake features. By contrast, no significant variations in fish lengths were found. |
