Differences in the fatty acid composition of larvae and metamorphosing sea lampreys, Petromyzon marinus

Biotechnological Production and Sensory Evaluation of ω1-Unsaturated Aldehydes

Lipid extracts of the fungus Flammulina velutipes were found to contain various scarce fatty acids including dodec-11-enoic acid and di- and tri-unsaturated C₁₆ isomers. A biotechnological approach using a heterologously expressed carboxylic acid reductase was developed to transform the fatty acids into the respective aldehydes, yielding inter alia dodec-11-enal. Supplementation studies gave insights into the fungal biosynthesis of this rarely occurring acid and suggested a terminal desaturation of lauric acid being responsible for its formation. A systematic structure-odor relationship assessment of terminally unsaturated aldehydes (C₇-C₁₃) revealed odor thresholds in the range of 0.24-22 μg/L in aqueous solution and 0.039-29 ng/L in air. In both cases, non-8-enal was identified as the most potent compound. All aldehydes exhibited green odor qualities. Short-chained substances were additionally associated with grassy, melon-, and cucumber-like notes, while longer-chained homologs smelled soapy and coriander leaf-like with partly herbaceous nuances. Dodec-11-enal turned out to be of highly pleasant scent without off-notes.

Muscle fatty acid profiles of sea lamprey (Petromyzon marinus L.) indicate the use of fast metabolized energy during ontogenesis

A comprehensive characterization of muscle's FA composition of sea lamprey ammocoetes and adults was performed to test the hypothesis that larvae, and early spawning migrants have a similar FA profile prior to metamorphosis and to spawning migration. Subsequently, the role played by FA signature in these two highly demanding stages of life cycle was inferred. The results confirm that muscle represents an important fat reservoir, and the FA trophic markers revealed the importance of bacteria as sources of iso and anteiso FA and the strong trophic representation of benthic phytoplankton (diatoms) to larvae muscle FA profile. In early spawning migrants, the significance of marine food web to FA muscle profile is highlighted by the presence of FA signatures characteristics of herbivorous calanoid copepods. Although both life cycle phases studied do not share the same muscle FA signature, there is a part of the profile that is common, which is characterized by FA used in β-oxidation, such as C18:1ω9 but also by medium chain FA and PUFA which points that PUFA are spared as fuel to β-oxidation process and probably used to the development of tissues membranes (ammocoetes) and gonadal development and eicosanoid production among others (early spawning migrants). Further studies on FA profile are necessary to elucidate the FA role either during different life stages (ontogeny) or in the distinct habitats frequented (freshwater versus marine) by this diadromous species.

Chemical Characterization of Lipophilic Constituents in the Skin of Migratory Adult Sea Lamprey from the Great Lakes Region

The sea lamprey (Petromzons marinus) is an invasive ectoparasite of large-bodied fishes that adversely affects the fishing industry and ecology of the Laurentian Great Lakes. Lipid content in the whole sea lamprey and muscles, liver and kidney of metamorphosing larval stages has been reported. Similarly, the fatty acid profile of the rope tissues of sexually-mature male sea lampreys has also been reported. The average body weight of a sub-adult migratory sea lamprey is 250 g, which includes 14.4% skin (36 g). Our preliminary extraction data of an adult sea lamprey skin revealed that it contained approximately 8.5% of lipophilic compounds. Lamprey skin is home to a naturally aversive compound (an alarm cue) that is being developed into a repellent for use in pest management. As part of an ongoing investigation to identify the chemical structure of the sea lamprey alarm cue, we extracted the skin with water and methanol, respectively. The methanolic extract (1.55%) contained exclusively lipophilic compounds and did not include the alarm cue. We chemically characterized all compounds present in the methanolic extract as cholesterol esters (CE), tri- and di-glycerides (TG and DG), cholesterol, free fatty acids (FFA) and minor amounts of plasticizers. The free fatty acids fraction was composed of saturated (41.8%), monounsaturated (40.7%) and polyunsaturated (17.4%) fatty acids, respectively. The plasticizers characterized were phthalate and benzoate and found to be 0.95 mg and 2.54 mg, respectively, per adult sea lamprey skin. This is the first report of the chemical characterization of all the lipophilic constituents in the skin of sub-adult migratory sea lamprey. The CEs isolated and characterized from sea lamprey skin are also for the first time.

The influence of acclimation temperature on the lipid composition of the larval lamprey, Petromyzon marinus, depends on tissue and lipid class

This study was designed to examine the effect of thermal acclimation on the lipid composition of fat depot organs the liver and kidneys of larval sea lamprey, Petromyzon marinus. We found that 21 °C-acclimated larvae possessed lower total lipid amounts in the liver (39% lower) and kidneys (30% lower) than 13 °C-acclimated larvae. Relatively lower lipid contents in the liver and kidneys of 21 °C-acclimated lamprey primarily resulted from a reduction in stored lipid reserve, triacylglycerol, but not the structural lipid, phospholipid. Compared to 21 °C-acclimated larvae, 13 °C-acclimated larvae were found to possess fewer saturated fatty acids (SFAs) and more unsaturated fatty acids (USFAs) in renal triacylglycerol and phospholipid classes, while there were no significant differences in the SFAs and USFAs of hepatic triacylglycerol, phospholipid, cholesteryl ester, fatty acid, and monoacylglycerol classes. Fewer SFAs, found in the kidney triacylglycerol of 13 °C-acclimated lamprey, were due to lower 12:0 and 14:0 fatty acids, but those in the renal phospholipid class were characterized by fewer 14:0, 15:0, and 16:0 fatty acids. More USFAs in renal triacylglycerol, as indicated by a higher unsaturation index, primarily resulted from higher polyunsaturated fatty acids (18:2ω6, 18:3ω3, and 18:4ω3); whereas, in the renal phospholipid class, this was a result of higher monoenes (18:1, 20:1, and 22:1ω9) and ω3 polyunsaturated fatty acids (18:4ω3). These data suggest that the influence of thermal acclimation on the lipid composition of lamprey fat depot organs depends on tissue and lipid class.