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Metamorphosis and diet often influence fatty acid (FA) signatures (FAS) of insects. We investigated FAS in a hematophagous ectoparasite, the deer ked (Lipoptena cervi). Deer keds shed their wings upon attachment on the host and, thus, the FAS of an individual blood-fed imago/pupa in the fur of its host can be traced back to the blood FA profile of a single moose (Alces alces). Host blood and different life stages of deer keds were investigated for FA by gas chromatography. The FAS of life stages resembled each other more closely than the diet. Blood meals modified the FAS of both sexes but the FAS of the blood-fed females were closer to those of the prepupae/pupae. The parasitizing males had higher proportions of major saturated FA (SFA) and polyunsaturated FA (PUFA) than the females, which contained more monounsaturated FA (MUFA) with higher ratios of n-3/n-6 PUFA and unsaturated FA (UFA)/SFA. The proportions of 16:1n-7 were <1% in the blood but 18% (males) and 29% (females) in the blood-fed keds. Allocation of lipids to offspring by the females and possible accumulation of PUFA in male reproductive organs may have induced these sex-related differences. MUFA percentages and UFA/SFA ratios increased while SFA and many PUFA decreased from the reproducing females to the pupae. The diapausing pupae displayed lowered n-3/n-6 PUFA ratios and could have mobilized 16:0 and 18:3n-3 for the most fundamental metabolic processes. In conclusion, FAS are modified through the life stages of the deer ked possibly due to their different FA requirements., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Composition of membrane lipids from the gills of juvenile Atlantic salmon (Salmo salar) in presmolt and smolt phases of development was compared among anadromous and non-anadromous populations. Three stocks migrating from spawning rivers to either lake (landlocked stock), brackish water or full strength sea water were grown under common garden conditions, and gill lipids and their acyl and alkenyl chains were examined in February (presmolts) and at the end of May (smolts) by mass spectrometry and gas-liquid chromatography. The most remarkable changes upon transition from the presmolt phase to the smolt phase were: (i) increase in the cholesterol/phospholipid ratio, (ii) decrease in the abundance of phosphatidylinositol (PI) content, (iii) increase in the amount of sulfatides, (iv) increase in phosphatidylcholine (PC) and phosphatidylethanolamine (PE) species with two highly unsaturated acyl chains, and finally (v) convergence of interstock differences in PC and PE species composition towards a similar lipid composition. Increases in the gill membrane content of cholesterol and sulfatides are discussed as pre-adaptation of salmon gills for salt-secretion, which may occur by increases in membrane microdomains (rafts) harboring ion channels and pumps. The decreases of PI were likely related to adjusting the gill membrane permeability to ions by diminishing prostanoid production. The similarity of those changes among three salmon stocks and the convergence of initially (presmolt phase) different PC and PE species profiles between the stocks towards similar lipid composition suggests that smoltification process of the gill epithelium is largely similar in anadromous and landlocked populations., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Factors regulating fatty acid (FA) composition of small herbivores are poorly known. Because of the fast response to food deprivation, the tissue FA profiles of voles could be rapidly modified. The selectivity of incorporating dietary FA into tissue total lipids and mobilizing tissue FA was examined in two Microtus vole species either fed or fasted for 12-18 h. The FA composition of the tissues reflected the dietary lipids, but FA were selectively incorporated depending on their structure. The FA profiles of white and brown adipose tissues were different and contained more saturated and monounsaturated FA and less polyunsaturated FA (PUFA) than the diet. The essential PUFA precursors with smaller tissue percentages were likely converted into longer-chain derivatives for structural lipids. The FA composition of the vole tissues was selectively modified by food deprivation. The preferences for retention or loss were tissue-specific and related to the FA structure. Livers displayed steatosis with characteristic accumulation of triacylglycerols, while FA prevalent in membrane phospholipids decreased in proportion. Hepatic FA could be partly derived from lipids hydrolyzed in fat depots. The FA profiles of the vole tissues reflect the dietary lipids and are rapidly and selectively modified by food deprivation., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Fatty acid (FA) composition in the intraabdominal (IAB), subcutaneous (SC) and peripheral adipose tissues of the semiaquatic American mink (Mustela vison) was examined in comparison to the diet by gas-liquid chromatography. There was a clear compositional gradient from the IAB via SC to peripheral adipose tissues and the anatomically different adipose tissues accumulated or metabolized FA selectively. The total lipids of the body appendages had smaller proportions of saturated (SFA) and larger proportions of monounsaturated (MUFA) and polyunsaturated fatty acids (PUFA) than the lipids of the trunk adipose tissues. Especially n-3 PUFA were enriched in the periphery. The appendages were also characterized with a high ratio of unsaturated FA to SFA, an increased Delta9-desaturation index and increased mean numbers of double bonds and carbon atoms in a FA molecule. The proportions of SFA and MUFA of the diet resembled the trunk adipose tissues while the dietary percentage of n-3 PUFA surpassed those of the trunk fat depots but was lower than those of the peripheral fats. These data confirm that the FA signatures of mammals reflect not only their dietary history but also metabolic modifications of ingested FA.

Effects of different fish-based diets (freshwater smelt, Baltic herring, marine herring/cod offal or their mixtures), gender, beta-glucan supplement, exogenous melatonin, and PCB exposure (Aroclor 1242((R)), 1 mg per animal per day in feed) on plasma immunoglobulin G (IgG) in the mink (Mustela vison) were studied. The aims of the study were to find out whether plasma IgG of the mink is affected by the subchronic PCB exposure, and whether biological, nutritional and hormonal effects are large enough to mask the possible IgG response. The concentration of IgG was determined using enzyme-linked immunosorbent assay (ELISA). Sexual dimorphism was detected, the males having higher levels of plasma IgG. In addition, melatonin tended to decrease IgG in females but not males. Diet also affected the humoral immune arm; the mixed-fish diets caused an unfavorable ratio of the oxidation products of lipids vs. vitamin E in liver, and resulted in low IgG concentration in plasma. In males fed Baltic herring, the beta-glucan supplement also lowered IgG levels. The PCBs failed to affect the plasma IgG of the smelt-fed female mink, and IgG concentration was not correlated with increased hepatic EROD activity or with the decreased total retinol in the liver of exposed mink. It is concluded that hormonal/seasonal and dietary factors affect the plasma IgG levels to such an extent that possible change in plasma IgG level due to PCBs in wild populations of mink is difficult to detect without a large amount of reference data.

Exogenous melatonin as subcutaneous 2.7-mg implants was given to eight female and male minks in late July with an equal number of animals in the control groups. The liver enzyme activities and major lipids of liver and plasma were measured in October-November. Melatonin had very pronounced effects on the lipid and carbohydrate metabolism of the minks and there was also a clear sexual dimorphism. In the males, melatonin decreased the lipase esterase activity of the liver. In the liver of the females, however, melatonin increased the glucose-6-phosphatase activity. Due to melatonin treatment the liver triacylglycerol contents diminished in both sexes. At the same time, in the females the liver cholesterol levels were decreased. In the plasma lipids, the only change was a fall in the polar lipids of the melatonin-treated females. Melatonin seems to be responsible for the metabolic changes associated with the onset of wintering, especially for the acceleration of the deposition of subcutaneous fat reserves. The smaller females experience the effects of exogenous melatonin more rapidly than the males. Perhaps the smaller body size requires an earlier onset of metabolic preparation for the winter.

Female minks (Mustela vison) fed diets based on freshwater, marine or mixed fish were exposed to 1 mg of polychlorinated biphenyls (PCBs) a day for 21 weeks. The plasma leptin and thyroxine concentrations and the glucose-6-phosphatase and glycogen phophorylase activities in the liver were measured at the end of the experiment. The plasma thyroxine concentrations were significantly higher in the group exposed to PCBs. The mean plasma leptin concentration and glucose-6-phosphatase activity was the highest in the group that had the lowest body-mass index (BMI). The glycogen phophorylase activity was the highest in the freshwater fish-control group. The results suggest that the amount of fat in the body of the female minks is not the only determinant of the plasma leptin levels, but the leptin levels seem to rise with a lowered BMI unlike in rodents or humans. The positive correlation between the leptin levels and the glucose-6-phosphatase activity suggests increased gluconeogenesis with high leptin levels. Subchronic exposure to PCBs seems to have no effect on the plasma leptin levels or the glucose-6-phophatase activities, but it elevates significantly the plasma thyroxine levels with a mechanism that remains unknown.

Nickel (10-100 ppm added as NiCl2) was studied to determine its effects on reproduction of Wistar rats. In nine experimental groups, females, males or both were exposed to nickel in drinking water. In one female group and one male group, the drinking water was also supplemented with 0.3 ppm selenium (added as Na2SeO3). Breeding success and the growth and viability of pups were recorded. Nickel, copper and zinc concentrations in kidneys, liver and skin (with fur) of the females, males and pups were determined with an atomic absorption spectrophotometer. In addition, histology of the male testes (from control and nickel-exposed groups) was studied. The female exposures started 14, 28 or 100 days before copulation and continued during pregnancy and lactation. When the males were exposed (for 28 or 42 days before copulation), NiCl2 reduced both the number of pregnancies and the number of pups born. In the testes, NiCl2 induced shrinkage of the seminiferous tubules, which seemed to close some of the tubules. In the tubules, NiCl2 decreased the number of basal spermatogonia. When the females or both parents were exposed to NiCl2, pup mortality during lactation was high. However, when the females were drinking NiCl2 supplemented with selenium, all the pups survived and development of the total mass of the litters was even better than in the control group. In the same way, in males, selenium supplementation of the drinking water protected those pups that were born; but fertility was lower than with the control treatment. In the tissues studied, nickel accumulated most in the kidneys and then in the liver and skin. In each type of organ, there was a clear dose response relationship. In the pups, in particular, selenium (given to the females) increased the amount of nickel in tissues compared with corresponding administration of nickel without selenium. In summary, selenium seemed to counteract the deleterious effects of NiCl2 on the reproduction of rats.

Fatty acid composition was determined in adipose tissue surrounding the mesenteric lymph nodes of mink (Mustela vison) exposed to polychlorinated biphenyls (PCBs: 1 mg Aroclor 1242 in food day-1 for 28 days) and/or copper (62 mg kg-1 food). These specific adipose tissues are known to have functional relationships with lymphocytes, and proliferation of cultured lymphocytes is influenced by the quality of fatty acids available in media. In six experimental groups the diet was based on freshwater fish, and in two groups it was based on marine fish. These basal diets differed in terms of fatty acid composition and content of fat-soluble vitamins A1 and E. The fatty acid composition of membrane phospholipids (PL) responded to PCBs more than that of triacylglycerols (TG). The effects of copper were small. In female minks fed a diet of freshwater fish, the proportion of highly unsaturated fatty acids in PL decreased by 5 wt.% due to PCBs, and the acids seemed to be replaced by monounsaturated fatty acids (9 wt.% increase of total). This decrease of highly unsaturated fatty acids in PL was milder in minks on the marine fish diet rich in fat-soluble vitamins. In TG of minks on the marine diet, however, PCBs decreased the proportion of docosahexaenoic acid (22:6n-3). The possibility that these alterations in the fatty acid metabolism of adipose tissue supporting the lymph nodes affect immune function during PCB exposure should be studied further. Interestingly, the quality of the fish diet affected the magnitude of the alterations. The fatty acid responses may also differ between males and females.

1. Adipose tissues associated with the mystacial and superciliary vibrissae of the Saimaa seal (Phoca hispida saimensis) contained 31% of hexadecenoic acid (16:1 omega 7), which was almost twice the already high amount in blubber. The amount of tetradecenoic acid (14:1 omega 5) was also double that in blubber. 2. At the same time the levels of long-chain highly unsaturated docosapentaenoic (22:5 omega 3) and docosahexaenoic acids (22:6 omega 3) were only two-thirds of those found in blubber. 3. It is suggested that the excess of low-melting monoenoic fatty acids (14:1 and 16:1) in adipose tissues near the vibrissae might not be compensation for the low supply of dietary polyunsaturated fatty acids in these tissues, but that the self-induced excess of monoenoic fatty acids ensured the proper functioning of these well-developed sense organs.

1. The main differences in fatty acid composition of blubber between the Saimaa seal (Phoca hispida saimensis) and the Baltic seals (Phoca hispida botnica and Halichoerus grypus) were, that in fresh water the proportions of polyunsaturated C18 acids and arachidonic acid (20:4 omega 6) were high. 2. The trend became more evident when data on ringed seals from northern oceans were compared with the present data. 3. The proportions of exogenous 20:1 and 22:1 were extremely low in ringed seals from Lake Saimaa and in Baltic seals compared with seals living in oceans.