The fatty acid composition of phospholipids from the eyes of the northern deepwater prawn, Pandalus borealis

Comparison of lipids and fatty acids among tissues of two semiterrestrial crabs reveals ecophysiological adaptations in changing coastal environments

Decapods have successfully colonized changing coastal habitats throughout the world by adapting their behavior, physiology, and biochemistry. Biochemical reserves, such as lipids and fatty acids (FAs), play fundamental roles in this adaptation process. These energy reserves are key for the development of decapods and their composition mainly depends on the type and quality of food available in their habitats. This study evaluated the lipid content and FA composition of three tissues (hepatopancreas, gills, and muscle) in two widely distributed, semi-terrestrial coastal crab species in Chile, Cyclograpsus cinereus from the upper intertidal and Hemigrapsus crenulatus from estuaries. This evaluation aimed to assess the physiological role of the bioenergetic reserves of these crabs, which tolerate fluctuating environmental conditions. Our results showed that both species had a higher lipid content in the hepatopancreas and a lower lipid content in its gills and muscle. All three of the evaluated tissues in C. cinereus showed high contents of saturated fatty acids (SFAs), and its hepatopancreas displayed the highest contents of monounsaturated (MUFAs) and polyunsaturated fatty acids (PUFAs). In turn, H. crenulatus had the highest contents of MUFAs and PUFAs in its gills and muscle tissues, including an important amount of eicosapentaenoic acid (EPA). The FA content of C. cinereus may indicate an adaptive physiological response aimed at maintaining its cellular fluid balance during periods of desiccation in the upper intertidal zone. In contrast, the FAs found in H. crenulatus may be linked to the high activity of the sodium‑potassium pump in its gills, in order to maintain osmoregulation in estuaries.

Changes in biochemical composition and digestive enzyme activity during the embryonic development of the marine crab, Charybdis japonica (Crustacea: Decapoda)

In this study, we investigated the biochemical composition and digestive enzyme activity during embryonic development in the marine crab, Charybdis japonica. Water, protein, and ash content increased, while levels of lipids and carbohydrates decreased significantly during embryonic development, and a marked correlation between water content and egg volume (r = 0.97; P < 0.01) was recorded. The utilization percentages of lipids and carbohydrates were 32.72% and 91.56%, respectively. The predominant essential amino acids (EAA) were lysine, leucine, arginine and valine, and the major nonessential amino acids (NEAA) were glutamic acid and aspartic acid. From the fertilized egg stage to the protozoea stage, total amino acid (TAA) concentration increased from 52.18% to 55.11% on a dry weight basis, but the ratio of EAA/TAA decreased from 52.57% to 48.90%. The quantitatively more important fatty acids were C16:0, C18:1n-9c, C16:1, C22:6n-3 (docosahexaenoic acid, DHA), and C22:2. Polyunsaturates (PUFA) and monounsaturated (MUFA) were consumed at similar rates (34.20% and 36.70%, respectively); both were consumed at higher rates than saturates (SFA) (26.56%). In particuler, n-3 fatty acids decreased significantly, with a high consumption rate of 43.74%. Activities of trypsin and pepsin increased during both the early and later embryonic stages, but decreased during the middle stages. Lipase activity increased gradually during embryonic development, except in the protozoea stage with a significant decrease, while activities of amylase and cellulase showed an ascending trend after an initial decline. The activity of all digestive enzymes increased, except for that of lipase, from the heartbeat stage to the protozoea stage.

Changes in amino acids and lipids during embryogenesis of European lobster, Homarus gammarus (Crustacea: Decapoda)

We studied the amino acid and lipid dynamics during embryogenesis of Homarus gammarus. Major essential amino acids (EAA) in the last stage of embryonic development were arginine, lysine and leucine; major nonessential amino acids (NEAA) were glutamic acid, aspartic acid, valine and glycine. The highest percent of utilization occurred in respect to EAA (27.8%), mainly due to a significant decrease (p<0.05) of methionine (38.3%) and threonine (36.0%). NEAA also decreased significantly (p<0.05, 11.4%), namely serine (38.1%), tyrosine (26.4%) and glutamic acid (25.7%). In contrast, the free amino acid content increased significantly (p<0.05) during embryonic development, especially the free nonessential amino acids (FNEAA). In the last stage, the most abundant FNEAA were glycine, proline, alanine and taurine, and the major free essential amino acids (FEAA) were arginine, lysine and leucine. Lipid content decreased significantly (p<0.05) during embryonic development. A substantial decrease in all neutral lipid classes was observed (>80% of utilization). Major fatty acids were 16:0, 18:0, 18:1n-9, 18:2n-6, 18:3n-3, 20:5n-3 and 22:6n-3. Unsaturated (UFA) and saturated fatty acids (SFA) were used up at similar rates (76.5% and 76.3%, respectively). Within UFA, monounsaturates (MUFA) were consumed more than polyunsaturates (PUFA) (82.9% and 67.5%, respectively).

Fatty acids of astaxanthin esters in krill determined by mild mass spectrometry

Krill is a major source of astaxanthin, which has strong antioxidant activity. Fractions with astaxanthin monoesters and diesters of Antarctic krill Euphausia superba were isolated. Astaxanthin esters were separated by C18-HPLC depending on the number of carbons and double bonds of esterified fatty acid(s). Small amounts of other lipids remained in the samples, but relative molecular masses of carotenoid esters could be measured by field desorption mass spectrometry without fragmentation and interference from contaminant lipids. The fatty acids were determined by calculation of difference between astaxanthin and astaxanthin esters. Only five kinds of fatty acids, dodecanoate, tetradecanoate, hexadecanoate, hexadecenoate and octadecenoate, were detected. Fast atom bombardment mass spectrometry and secondary ion mass spectrometry showed similar spectra. The fatty acid composition in astaxanthin esters was different from those in krill lipids. Therefore, determination of fatty acids in carotenoid esters by a combination of HPLC elution profile and mild mass spectrometry is found to be a useful tool.