Lipid class dynamics during development in early life stages of shortbelly rockfish and their application to condition assessment

Lipid class dynamics and the relationship between weight and length were analysed during early life stage (ELS) development in wild populations of shortbelly rockfish Sebastes jordani to investigate their utility in a condition or nutritional status assessment. Analyses from more than 3000 field-captured shortbelly rockfish indicated little variation in weight for a given length and provided limited application in the assessment of condition. The fractionation of total lipids into individual classes revealed trends in lipid metabolism throughout development. These trends were described best using a stage-specific regression model, since Sebastes show defined early life history transitions. Among developmental stages, triacylglycerols (TAG) and polar lipids (PL) were the dominant lipid classes and cholesterol (CHOL), sterol/wax esters, and nonesterified fatty acids were found in lower concentrations. In the preflexion stage, low concentrations and constant levels of TAG along with the combined influence of endogenous and exogenous sources of energy compromised the use of TAG as an index of nutritional status. However, during flexion through juvenile stages, TAG levels increased indicating an accumulation of energy reserves with development, thus providing a valid indicator of nutritional status in later stages. Large fluctuations in PL concentrations during development suggested complex metabolism which may be due to changes in cell volume and cell membrane proliferation with development as well as catabolism. CHOL declined in larval stages, then remained constant with increasing size through the juvenile stage, negating its use as a normalizer for variations of mass in a TAG/CHOL ratio prior to juvenile transformation. This study provides the first documentation of lipid dynamics during early life stages following parturition in a marine viviparous teleost.     

Thematic review series: Lipid droplet synthesis and metabolism: from yeast to man. Lipid droplet-based storage fat metabolism in Drosophila

The fruit fly Drosophila melanogaster is an emerging model system in lipid metabolism research. Lipid droplets are omnipresent and dynamically regulated organelles found in various cell types throughout the complex life cycle of this insect. The vital importance of lipid droplets as energy resources and storage compartments for lipoanabolic components has recently attracted research attention to the basic enzymatic machinery, which controls the delicate balance between triacylglycerol deposition and mobilization in flies. This review aims to present current insights in experimentally supported and inferred biological functions of lipogenic and lipolytic enzymes as well as regulatory proteins, which control the lipid droplet-based storage fat turnover in Drosophila.     

Lipid composition and storage in the tissues of the bivalve, Macoma balthica

Total lipid content, lipid classes and fatty acid composition in organs of Macoma balthica (L.) from the Gulf of Gdánsk (Puck Bay) were studied in different seasons. Marked differences among tissues in lipid class composition were observed. Triacylglycerides were accumulated in the hepatopancreas and in the female gonad in large quantities, while hydrocarbons were concentrated in male gonads, gills muscles and mantle. Fatty acid composition of gill lipids reflects the brackish water conditions of the Gulf of Gda sk in which Macoma balthica occurs.     

Neurological Mutation Characterized by Dysmyelination in NCTR-Balb/C Mouse with Lysosomal Lipid Storage Disease

Abstract: Morphological and biochemical studies were performed on the CNS of neurologically affected NCTR Balb/C mouse. Histological and electron microscopic techniques demonstrated severe myelin deficiency in the affected brains. Neither the presence of lipid-containing macrophages nor reactive gliosis was apparent. Analysis of myelin-associated lipids and proteins revealed prominent depletion of galactocerebroside, sulfatide, and proteolipid proteins. In contrast to the scarcity of myelin specific constituents a marked accumulation of G_M2 and G_M3 gangliosides and several neutral glycolipids, i.e., glucocerebroside, lactosylceramide, gangliotriaosylceramide, and gangliotetraosylceramide were found in affected CNS. These abnormalities were already apparent in 12-day-old pups as well as in 65-day-old mice. A significant deficit in the proportion of long-chain fatty acids (C₂₄), notable in both normal and α-hydroxy acids of cerebrosides from affected white matter, was measured. The lack of reactive gliosis, the observed depletion of galactocerebroside and sulfatide at the early age of 12 days, and the relative decrease in long-chain fatty acids in affected CNS strongly suggest a defect in myelinogenesis in this mutant rather than a secondary process of myelin breakdown.     

Variation of body condition and plasma energy substrates with life stage,sex, and season in wild-sampled nurse sharks Ginglymostoma cirratum

Reported here are the relationships among morphological (i.e., body condition) and biochemical (i.e., plasma concentrations of triglycerides, cholesterol, free fatty acids, and ketone bodies and ketone body ratios) parameters related to energy storage and use, as well as the variation of such parameters, for 107 free-ranging nurse sharks Ginglymostoma cirratum sampled off South Florida. Immature G. cirratum exhibited a higher variance in body condition, plasma free fatty acid concentrations and ketone body ratios compared to adults. Mature female G. cirratum had significantly higher body condition than mature males, driven by a seasonal increase in mature female body condition during the wet season. Mature male G. cirratum showed a decrease in the ketone body β-hydroxybutyric acid during the dry season. Taken together, this study provides a baseline assessment of body condition and internal physiological state for a data-poor marine species and demonstrates significant ontogenetic, sexual and seasonal variation in G. cirratum energetic state. As concluded by other studies of energy metabolism in free-ranging sharks, this research highlights the importance of considering intraspecific patterns and sampling context for inferring the drivers of variation.     

Metabolic regulation of triacylglycerol accumulation in the green algae: identification of potential targets for engineering to improve oil yield

The great need for more sustainable alternatives to fossil fuels has increased our research interests in algal biofuels. Microalgal cells, characterized by high photosynthetic efficiency and rapid cell division, are an excellent source of neutral lipids as potential fuel stocks. Various stress factors, especially nutrient‐starvation conditions, induce an increased formation of lipid bodies filled with triacylglycerol in these cells. Here we review our knowledge base on glycerolipid synthesis in the green algae with an emphasis on recent studies on carbon flux, redistribution of lipids under nutrient‐limiting conditions and its regulation. We discuss the contributions and limitations of classical and novel approaches used to elucidate the algal triacylglycerol biosynthetic pathway and its regulatory network in green algae. Also discussed are gaps in knowledge and suggestions for much needed research both on the biology of triacylglycerol accumulation and possible avenues to engineer improved algal strains.     

Resource dependent growth and body condition dynamics in juvenile snakes: an experiment

We examined the manner in which animals adjust the proportion of energy allocated to growth and storage in response to food availability. We compared univariate growth and length-mass relationships between juvenile adders (Vipera berus) reared under two different feeding regimes. Animals in the low- and high-food experimental groups were fed suckling mice once and twice weekly, respectively. Snout-vent length, body mass, and body condition (residual scores from log-log regression of body mass on snout-vent length) were measured shortly after birth, and at 4, 9, and 14 weeks. We found that growth in length and mass, as well as changes in length-mass relationships, differed between treatments; snakes with access to more food not only increased faster in length but were also heavier at the completion of the experiment than were similar sized less frequently fed snakes. There was no association between body condition of individuals measured at birth and at the end of the experiment, whereas size at birth was a good predictor of final size. Our results provide evidence for resource-dependent allocation strategies in V. berus, and suggest that somatic growth is less sensitive to environmental fluctuations than body condition, presumably because body size is of greater importance for fitness.     

Deciduous and evergreen trees differ in juvenile biomass allometries because of differences in allocation to root storage

Background and Aims

Biomass partitioning for resource conservation might affect plant allometry, accounting for a substantial amount of unexplained variation in existing plant allometry models. One means of resource conservation is through direct allocation to storage in particular organs. In this study, storage allocation and biomass allometry of deciduous and evergreen tree species from seasonal environments were considered. It was expected that deciduous species would have greater allocation to storage in roots to support leaf regrowth in subsequent growing seasons, and consequently have lower scaling exponents for leaf to root and stem to root partitioning, than evergreen species. It was further expected that changes to root carbohydrate storage and biomass allometry under different soil nutrient supply conditions would be greater for deciduous species than for evergreen species.

Methods

Root carbohydrate storage and organ biomass allometries were compared for juveniles of 20 savanna tree species of different leaf habit (nine evergreen, 11 deciduous) grown in two nutrient treatments for periods of 5 and 20 weeks (total dry mass of individual plants ranged from 0·003 to 258·724 g).

Key Results

Deciduous species had greater root non-structural carbohydrate than evergreen species, and lower scaling exponents for leaf to root and stem to root partitioning than evergreen species. Across species, leaf to stem scaling was positively related, and stem to root scaling was negatively related to root carbohydrate concentration. Under lower nutrient supply, trees displayed increased partitioning to non-structural carbohydrate, and to roots and leaves over stems with increasing plant size, but this change did not differ between leaf habits.

Conclusions

Substantial unexplained variation in biomass allometry of woody species may be related to selection for resource conservation against environmental stresses, such as resource seasonality. Further differences in plant allometry could arise due to selection for different types of biomass allocation in response to different environmental stressors (e.g. fire vs. herbivory).     

Comparative lipidomic studies of Scenedesmus sp. (Chlorophyceae) and Cylindrotheca closterium (Bacillariophyceae) reveal their differences in lipid production under nitrogen starvation

Microalgae are a promising resource for the highly sustainable production of various biomaterials (food and feed), high‐value biochemicals, or biofuels. However, factors influencing the valued lipid production from oleaginous algae require a more detailed investigation. This study elucidates the variations in lipid metabolites between a marine diatom (Cylindrotheca closterium) and a freshwater green alga (Scenedesmus sp.) under nitrogen starvation at the molecular species level, with emphasis on triacylglycerols using liquid chromatography–electrospray ionization mass spectrometry techniques. A comprehensive analysis was carried out by comparing the changes in total lipids, growth kinetics, fatty acid compositions, and glycerolipid profiles at the molecular species level at different time points of nitrogen starvation. A total of 60 and 72 triacylglycerol molecular species, along with numerous other polar lipids, were identified in Scenedesmus sp. and C. closterium, respectively, providing the most abundant triacylglycerol profiles for these two species. During nitrogen starvation, more triacylglycerol of Scenedesmus sp. was synthesized via the “eukaryotic pathway” in the endoplasmic reticulum, whereas the increase in triacylglycerol in C. closterium was mainly a result of the “prokaryotic pathway” in the chloroplasts after 96 h of nitrogen starvation. The distinct responses of lipid synthesis to nitrogen starvation exhibited by the two species indicate different strategies of lipid accumulation, notably triacylglycerols, in green algae and diatoms. Scenedesmus sp. and Cylindrotheca closterium could serve as excellent candidates for the mass production of biofuels or polyunsaturated fatty acids for nutraceutical purposes.     

Development and validation of methods for measuring multiple biochemical indices of condition in juvenile fishes

The investigation established and validated methods to measure multiple biochemical indices of condition (whole body total lipids, whole body triglycerides, muscle RNA : DNA ratio and muscle protein) simultaneously in the same individual juvenile fish. It also provided examples of their application using a species comparison (salmonids and cyprinids) of the degree of change in these indices after food deprivation. The results showed that juvenile rainbow trout Oncorhynchus mykiss were much more susceptible to a decline in all biochemical indices of condition than juvenile fathead minnows Pimephales promelas upon food deprivation. The combination of these techniques can be used to accurately assess condition and growth potential of individuals from wild fish populations.     

Neutral lipid storage disease: a possible functional defect in phospholipid-linked triacylglycerol metabolism

Neutral lipid storage disease (NLSD) (Chanarin-Dorfman Syndrome) is an autosomal recessive disorder of multisystem triacyglycerol (TAG) storage. Previous work has pointed to a defect in intracellular TAG metabolism. In the studies reported here, the lipid metabolism of three lines of NLSD fibroblasts were compared to normal skin fibroblasts. When pulsed with [³H]oleic acid, the earliest observed abnormality in NLSD cell lines was increased incorporation into phosphatidylethanolamine, followed by accumulation of radiolabel in TAG. Activities of several glycerolipid synthetic enzymes were comparable in NLSD and normal fibroblast lines, excluding oversynthesis of glycerolipid. The proportion of plasmalogen and neutral ether lipid synthesized was normal and alkylglycerols did not accumulate, excluding a defect in ether lipid metabolism. Activities of both acid lipase and Mn²⁺-sensitive lipase within the particulate fractions of NLSD and normal fibroblasts were comparable. These studies are most consistent with functional deficiency of a TAG lipase with activity against a pool of TAG that are normally utilized for phospholipid biosynthesis.     

Fatty acid binding protein expression in different human adipose tissue depots in relation to rates of lipolysis and insulin concentration in obese individuals

Two fatty acid binding proteins (FABPs) are expressed in adipose tissue, adipocyte lipid binding protein (ALBP) and keratinocyte lipid binding protein (KLBP). This study investigated FABP expression in visceral and subcutaneous human adipose tissue depots and associations with lipolytic differences between the depots and circulating insulin concentrations. ALBP and KLBP (protein and RNA) were quantified in subcutaneous and omental adipose tissue from obese individuals and expressed relative to actin. ALBP RNA and protein expression was significantly higher in subcutaneous compared to omental adipose tissue (both p < 0.05), whereas KLBP RNA and protein expression was no different between the two sites. There were significant inverse correlations between serum insulin concentrations and the ALBP/KLBP RNA ratio in both subcutaneous and omental adipose tissue (both p < 0.02). Basal rates of glycerol and fatty acid release measured in adipocytes isolated from subcutaneous and omental adipose tissue were significantly higher in the former (p 0.02). Therefore the relative ALBP/KLBP content of human adipose tissue is different in different adipose tissue depots and at the RNA level is related to the circulating insulin concentration, at least in obese subjects. The higher rates of basal lipolysis in adipocytes isolated from subcutaneous compared to omental adipose tissue might be related to the increased ALBP content of the former. Therefore adipose tissue FABPs are interesting candidates for investigation to further our understanding of the insulin resistance syndrome and regulation of lipolysis.     

A simple and rapid method to assay triacylglycerol in cells and tissues

We have developed a reliable, rapid, and economical assay for the quantification of triacylglycerol (TG) in cells and animal tissues. In a few hours, this assay quantifies microgram amounts of TG from tens or even hundreds of samples. The protocol includes an organic extraction to partition TG away from proteins and other hydrophilic molecules found in cells and tissues that may interfere with the colorimetric enzyme-linked TG detection method. In addition, this assay is economical, as no expensive reagents, supplies, or equipment are needed. Another benefit of this assay is that it does not require environmentally unfriendly halogenated solvents.     

Yolk lipids and their fatty acids in the wild and captive ostrich (Struthio camelus)

A comparative study has been made of the major lipid fractions and their fatty acid compositions in the yolk of eggs from ostriches under wild and farmed conditions. There were no differences in the lipid contents and proportions of the lipid fractions between the two groups of yolks. In both groups of yolks triacylglycerol and phospholipid were the major fractions. In the eggs from the wild ostriches, all the lipid fractions displayed substantial concentrations of C18 polyunsaturated fatty acids, triacylglycerol being particularly rich in linolenic acid and phospholipid rich in linoleic acid; phospholipid displayed substantial concentrations also of C20 and C22 polyunsaturates. There were considerable differences in the fatty acid compositions between the yolks. Those from the farmed birds displayed lower proportions of C18 polyunsaturates, particularly linolenic acid, throughout the lipid fractions. Compensatory increases were displayed most obviously in the concentrations of oleic acid and palmitoleic acid as well as other acids. The distinctive and extensive changes in fatty acid composition, particularly relating to the polyunsaturates, are discussed with respect to overall dietary requirements and specificities for embryo metabolism and possible effects on reproductive performance.     

Plasma Leptin Response to an Epinephrine Infusion in Lean and Obese Women

Objective: Because leptin production by adipose tissue is under hormonal control, we examined the impact of epinephrine administration on plasma leptin concentrations. Research Methods and Procedures: We measured plasma leptin, insulin, and free fatty acid (FFA) responses after a 60-minute epinephrine infusion (0.010 μg/kg fat free mass/min) followed by a 30-minute recovery period (no infusion) in a group of 11 lean (mean body mass index ± SD: 22.6 ± 1.1 kg/m²) and 15 obese (30.0 ± 1.3 kg/m²) premenopausal women. Leptin, insulin, and FFA levels were measured in plasma before (−15 and 0 minutes) and at every 30 minutes over the 90-minute period. Results: In both lean and obese individuals, plasma leptin was significantly reduced by epinephrine (p < 0.0001). Body fat mass was associated with fasting leptin levels (r = 0.64, p < 0.0005) as well as with the decrease in leptinemia (r = −0.51, p < 0.01) produced by epinephrine administration. Furthermore, we noted a large range of leptin response to epinephrine among our subjects, especially in obese women (from −12 to −570 ng/mL per 60 minutes). However, there was no association between postepinephrine leptin and FFA levels (r = −0.14, p = 0.55). Discussion: Results of this study indicate that leptin levels decrease after epinephrine administration in both lean and obese premenopausal women. However, the heterogeneity in the response of leptin to catecholamines suggests potential alterations of the leptin axis that may contribute to generate a positive energy balance and, thus, may favor weight gain in some obese individuals.     

Relationships of Plasma Leptin Levels to Changes in Plasma Free Fatty Acids in Women Who Are Lean and Women Who Are Abdominally Obese

HENNES, MAGDA MI, ARNAVAZ DUA, DIANA L MAAS, GABRIELE E SONNENBERG, GLENN R KRAKOWER, AHMED H KISSEBAH. Relationships of plasma leptin levels to changes in plasma free fatty acids in women who are lean and women who are abdominally obese. Regulation of leptin production by the hormonal and metabolic milieu is poorly understood. Because abdominal obesity is commonly associated with elevated plasma free fatty acid (FFA) flux, we examined the effects of augmenting FFA on plasma leptin levels in women who were lean and of suppressing FFA in women with abdominal obesity. In study 1, nine subjects who were lean, after a 12-hour overnight fast, received either intravenous saline or Intralipid plus heparin to increase the plasma FFA concentration to approximately 1000 μmol/ L. After 3 hours of additional fasting, subjects underwent 3-hour hyperglycemic clamps. In study 2, seven subjects with abdominal obesity were evaluated by a similar protocol, but lipolysis and plasma FFA flux were instead maximally suppressed by acipimox. In the individuals who were lean, leptin levels were unchanged during clamping. Increasing plasma FFA reduced plasma leptin from 7.66 ± 0.66 to 7.05 ±0 0.66 (p=0.03), but 3 hours of hyperglycemia plus hyperinsulinemia had no additional effect on leptin levels (7.15 ± 0.71). Basal leptin levels, 4-fold higher in the subjects with obesity, were reduced from 34.6 ± 2.4 μg/L to 32.3 ± 1.1 μg/L (p=0.004) during the clamp period. When plasma FFA flux was suppressed, however, plasma leptin levels after clamped hyperglycemia/hyperinsulinemia were increased to 38.9 ± 1.2 μg/L (p=0.014 vs. time 0 and 0.001 vs. saline protocol). Changes in leptin concentrations are not correlated with changes in FFA. These results suggest that plasma FFA concentration does not regulate plasma leptin levels in basal, extended fasting, or hyperglycemic/hyperinsulinemic states.     

Lipid droplets formation in human endothelial cells in response to polyunsaturated fatty acids and 1‐methyl‐nicotinamide (MNA); confocal Raman imaging and fluorescence microscopy studies

In this work the formation of lipid droplets (LDs) in human endothelial cells culture in response to the uptake of polyunsaturated fatty acids (PUFAs) was studied. Additionally, an effect of 1‐methylnicotinamide (MNA) on the process of LDs formation was investigated. LDs have been previously described structurally and to some degree biochemically, however neither the precise function of LDs nor the factors responsible for LD induction have been clarified. Lipid droplets, sometimes referred in the literature as lipid bodies are organelles known to regulate neutrophil, eosinophil, or tumor cell functions but their presence and function in the endothelium is largely unexplored. 3D linear Raman spectroscopy was used to study LDs formation in vitro in a single endothelial cell. The method provides information about distribution and size of LDs as well as their composition. The incubation of endothelial cells with various PUFAs resulted in formation of LDs. As a complementary method for LDs identification a fluorescence microscopy was applied. Fluorescence measurements confirmed the Raman results suggesting endothelial cells uptake of PUFAs and subsequent LDs formation in the cytoplasm of the endothelium. Furthermore, MNA seem to potentiate intracellular uptake of PUFAs to the endothelium that may bear physiological and pharmacological significance.

Confocal Raman imaging of HAoEC cell with LDs.