To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure email@example.com
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
In Mars-analogous hyperarid soils of the Atacama Desert, phospholipid fatty acids (PLFAs) as the main component of biomembrane play a role in reliably determining viable microbes. PLFA analyses illustrated a rise of the microbial abundance (from 5.0 × 106 to 4.2 × 107 cells g−1) and biodiversity (from 7 to 15 different individual PLFAs) from the north hyperarid core of the Atacama Desert to the southern arid region. Abundant cyclopropyl PLFAs (47.2 ± 4.6%) suggested the resistance to oligotrophic and hypersaline environments by Atacama microbial communities. The southernmost arid site had the highest proportion (8.7%) of eukaryotic and fungal lipid biomarkers. Different precipitations (ranging from 0.7 to 2 mm year−1) in the hyperarid core exerted different effects on microbial biomass, PLFA diversity, bacteria and microeukaryotes. By principal component analysis (cumulative 74.6% of variance), the dominance of PLFA hydroxylation was associated with the microbial viability; bacteria rich in C16:0, C18:0 and C16:1ω9 favoured higher soil conductivity and nitrate; and other PLFAs contributed more to the organic content. Additionally by comparing the ratios of PLFAs to well-preserved organics (e.g., mineral-bound organic carbon and microbial phosphorus), I found that the degradation of PLFAs decreased to a minimum when the mean annual precipitation is lower than 2 mm. These findings may further specify identifiable biomarkers on Mars, if potentially extant Martian microbes possess comparable phospholipid membrane structure.
Metabolic abnormality is common among schizophrenia patients. Some metabolic traits were found associated with subgroups of schizophrenia patients.
We examined a possible relationship between metabolic abnormality and psychosis profile in schizophrenia patients.
Three hundred and seventy-two chronic schizophrenia patients treated with antipsychotics for more than 2 years were assessed with the Positive and Negative Syndrome Scale. A set of metabolic traits was measured at scheduled checkpoints between October 2004 and September 2006.
Multiple regressions adjusted for sex showed negative correlations between body mass index (BMI) and total score and all subscales; triglycerides (TG) was negatively correlated with total score and negative syndrome, while HDLC was positively correlated with negative syndrome. When sex interaction was concerned, total score was negatively correlated with BMI but not with others; negative syndrome was negatively correlated with BMI and positively with HDLC. No metabolic traits were correlated with positive syndrome or general psychopathology.
Loss of body weight is a serious health problem in schizophrenia patients with severe psychosis syndrome, especially the negative syndrome. Schizophrenia patients with severe negative syndrome may have a distinct lipid pathophysiology in comparison with those who were less severe in the domain.
Many studies have shown that metabolic efficiency of ruminants can be significantly decreased when B-vitamin supply is insufficient. Under the present state of knowledge, the amounts of B vitamins available for intestinal absorption cannot be predicted based on diet composition. Therefore, in an attempt to increase our understanding of the effects of dietary factors, on B-vitamin supply for dairy cows, the effects of increasing amounts of extruded linseed in diets based on hay (permanent grassland hay, H; Experiment 1) or corn silage (CS; Experiment 2) on apparent ruminal synthesis (ARS) of thiamin, riboflavin, niacin, vitamin B6, folates and vitamin B12 were evaluated. In each experiment, four lactating Holstein cows fitted with cannulas in the rumen and the proximal duodenum were used in a 4 × 4 Latin square design. In both experiments, the dietary treatments consisted of an increasing supply of extruded linseed representing 0%, 5%, 10% or 15% of diet DM. The forage : concentrate ratios were 50 : 50 and 60 : 40 for Experiments 1 and 2, respectively. Duodenal flow was determined using YbCl3 as a marker. The ARS of each B vitamin was calculated as duodenal flow – daily intake. In both experiments, treatments did not affect thiamin, riboflavin, niacin and vitamin B12 duodenal flow or ARS. Increasing the dietary concentration of extruded linseed decreased folate intake in Experiment 1 and vitamin B6 intake in Experiment 2 but resulted in a greater duodenal flow of vitamin B6 and folates regardless of the forage used in basal diet. Greater dietary linseed concentrations decreased vitamin B6 apparent degradation in the rumen in CS-based diet only and increased folate ARS in both H- and CS-based diets. Increasing linseed concentration of isonitrogenous and isoenergetic diets increased vitamin B6 and folate supply to dairy cows, both with H- and CS-based diets.
Human embryo studies have proposed the use of additional morphological evaluations related to the moment of the first cell divisions as relevant to embryo viability. Nevertheless, there are still not enough data available related to morphokinetic analysis and its relationship with lipid composition in embryos. Therefore, the aim of this study was to address the lipid profile of bovine embryos with different developmental kinetics: fast (four or more cells) and slow (two or three cells) at 40 h post-insemination (hpi), at three time points of in vitro culture (40, 112 and 186 hpi) and compare these to profiles of in vivo embryos. The lipid profiles of embryos were analyzed by matrix-assisted laser desorption ionization mass spectrometry, which mainly detected pools of membrane lipids such as phosphatidylcholine and sphingomyelin. In addition to their structural function, these lipid classes have an important role in cell signalling, particularly regarding events such as stress and pregnancy. Different patterns of lipids in the fast and slow groups were revealed in all the analyzed stages. Also, differences between in vitro embryos were more pronounced at 112 hpi, a critical moment due to embryonic genome activation. At the blastocyst stage, in vitro-produced embryos, despite the kinetics, had a closer lipid profile when compared with in vivo blastocysts. In conclusion, the kinetics of development had a greater effect on the membrane lipid profiles throughout the embryo culture, especially at the 8–16-cell stage. The in vitro environment affects lipid composition and may compromise cell signalling and function in blastocysts.
This chapter deals with the inherited metabolic diseases affecting the heart in which there are morphological changes sufficient to permit a tentative diagnosis to be offered by a pathologist. A large first section deals with glycogen storage disorders and is well illustrated. This is followed by discussion of lysosomal storage disorders, including Niemann–Pick disease, sections on mucopolysaccharidosis and of the commoner disorders of lipid oxidation. Disorders of iron metabolism and amino acidurias close the chapter.
Research has shown both production and health benefits for the use of chicory (Cichorium intybus) within ruminant diets. Despite this, little was known about the effects of this forage, containing differing fatty acid profiles and secondary plant compounds compared with ryegrass, on beef stability, fatty acid composition or sensory properties. An experiment was conducted to investigate whether the inclusion of chicory in the diet of grazing beef steers would alter these three properties in the M. Longissimus muscle when compared with beef steers grazing perennial ryegrass (Lolium perenne). Triplicate 2 ha plots were established with a chicory (cv. Puna II)/perennial ryegrass mix or a perennial ryegrass control. A core group of 36 Belgian Blue – cross steers were used within a 2-year beef finishing experiment (n=6/replicate plot). In the 2nd grazing year, steers were slaughtered as they reached a target fat class of 3. Muscle pH was checked 2 and 48 h post-slaughter. A section of the hindloin joint containing the M. Longissimus lumborum muscle was removed and a 20 mm-thick steak was cut and muscle samples were taken for analysis of vitamin E and fatty acid analysis. The remaining section of the loin was vacuum packed in modified atmosphere packs and subjected to simulated retail display. A section of the conditioned loin was used for sensory analysis. Data on pH, vitamin E concentration and colour stability in a simulated retail display showed there were no effects of including chicory in the diet of grazing beef steers on meat stability. There were also no differences found in the fatty acid composition or the overall eating quality of the steaks from the two treatments. In conclusion, there were no substantive effects of including chicory in the swards of grazing beef cattle on meat stability, fatty acid composition or sensory properties of the M. Longissimus muscle when compared with beef steers grazing ryegrass-only swards.
Pleuroncodes monodon, an important fishery resource and key species in the Humboldt Current Large Marine ecosystem, has a prolonged reproductive period from winter until end of summer, and during this time females incubating their embryos are exposed to seasonal variation in food availability and in temperature. Additionally, in order to ensure successful reproduction and survival of embryos, changes occur in the main internal reserves and/or sources of energy of P. monodon. The aim of this study was to determine the extent of seasonal variation (winter vs summer) in the lipid content and fatty acid composition of ovigerous females and their embryos. The results show that a higher percentage of saturated and polyunsaturated fatty acids are found in females in winter. Similarly, the composition of fatty acids in embryos found here indicates that winter embryos have more saturated fatty acids and essential fatty acids (C18:2n6cis, C18:3n6 and C22:6n3) than do summer embryos. According to PCA analysis of fatty acid profile, samples from summer may be distinguished into two isolated groups with conspicuous variations in fatty acids profile of embryo and hepatopancreas. While in winter, the opposite pattern occurs in the fatty acid profile of embryo and hepatopancreas. These variations may be related to relevant physiological processes (reproduction and growth) and of their ontogeny (development and survival of offspring). Seasonal variation in the lipid content and composition of fatty acids of P. monodon could directly impact this species’ reproduction and survival and subsequently could have consequences on the food web and fishery exploitation.
Seed composition, including the protein, lipid and sucrose contents of 334 accessions of wild soybean (Glycine soja) collected in Japan, was evaluated using near-infrared reflectance spectroscopy (NIRS) technology. The distribution of protein, lipid and sucrose contents and correlations among these three classes of seed components were determined. Protein, lipid and sucrose levels ranged in accessions from 48.6 to 57.0, 9.0 to 14.3 and 1.24 to 3.53%, respectively. Average levels of protein, lipid and sucrose in the accessions were 54, 11 and 2.5%, respectively. High negative correlations were observed between the protein and lipid contents, and the protein and sucrose contents. Mean levels of the three constituents were compared among collection sites classified by climatic conditions. The total protein content of accessions from regions with a high annual mean temperature was high. The protein content of accessions from the II-1 region was higher than those from the III-3 region, and the sucrose content from the II-1 region was lower than those from regions III-2 and IV-3. The lipid content of plants from the II-1 region was lower than those from other regions, and the accessions in region II had a higher protein content and lower sucrose and lipid contents than the other regions. These results provide diverse and wide-ranged protein, lipid and sucrose contents information of Japanese wild soybean resources according to climatic region; thus, providing a foundation for the future development and selection of new soybean varieties with desired traits in global environmental changes.
Se supplementation in feed can be used to increase human Se intake, and this has showed significant progress in the area of healthy nutrition in recent years. It has been proven that the antioxidant function of Se is likely to contribute to better shelf life in animal products. Egg freshness can be monitored by assessment of albumen and yolk pH, fatty acid profile, malondialdehyde content, yolk vitelline membrane strength, carbonyl content and yolk pigment stability. It has been proven that Se reduces oxidation processes inside the egg and hence the pH of its contents does not increase too rapidly when stored. Several studies have reported that the rate of fatty acid oxidation and the production of lipid oxidation products (malondialdehyde, MDA) are lower in Se enriched eggs compared to non-enriched eggs. These results have been explained by an increase in gluthation peroxidase (GSH-Px) levels and activity in eggs after supplementation of laying hens with Se, which is an essential component of GSH-Px. Se has a positive effect on the stability of yolk pigments, which is linked to the oxidation stability of yolk lipids. According to several studies, Se decreases the carbonyl, which is a marker of protein oxidation. The yolk vitelline membrane consists of a high amount of protein incorporating Se, which explains the increased vitelline membrane strength after Se supplementation.
The influence of young, mature and senescent leaves of bitter gourd Momordica charantia L. (Cucurbitaceae) on the feeding, growth and reproduction of Epilachna dodecastigma (Weid.) (Coleoptera: Coccinellidae) were studied under laboratory conditions (27 ± 0.5 °C, 12 h light: 12 h dark photoperiod, 65 ± 5% RH). Larval developmental time of E. dodecastigma was longest on senescent leaves followed by young and mature leaves, whereas the pupal period was shortest on young and mature leaves. The longevity of females was generally higher than males. Male and female longevity were highest on mature leaves and lowest on senescent leaves. Fecundity was highest on mature leaves followed by young and senescent leaves. The growth and development of E. dodecastigma were related with nutrient and phenol content of three types of bitter gourd leaves. Carbohydrate content was higher in young and mature leaves, whereas protein, nitrogen, amino acid and lipid content were in greater quantities in mature leaves followed by young and senescent leaves. Phenol content was greatest in senescent leaves and least in mature leaves. Higher level of carbohydrates, proteins, lipids, nitrogen and amino acids including water content and lower phenol content of mature leaves had influenced higher growth rate and fecundity of E. dodecastigma.
Orchid seeds are among the smallest seeds in nature and they are naturally rich in fatty acids. However, the fatty acid composition of orchid seeds has not been investigated because the sample masses utilized for widely used methods for fatty acid profiling would generally require prohibitively large numbers (i.e. 10,000s) of seeds. The present work aimed to develop a method for fatty acid analysis using gas chromatography–mass spectrometry on small quantities (mg) of seeds. The method was developed using the seeds of two species, Dactylorhiza fuchsii, a temperate terrestrial, and Grammatophyllum speciosum, a tropical epiphyte. A range of sample masses was tested to determine the minimum mass required to achieve reliable fatty acid composition data. A direct transesterification method was used, which did not require extraction of fatty acids from seeds prior to analysis, and the effects of seed processing (crushed versus intact seeds) and incubation time in toluene on fatty acid yield were tested. Stable fatty acid profiles were obtained using as little as 10 mg of seeds. Neither crushing the seeds nor extending the toluene incubation step had much effect on the fatty acid yield. The simple direct transesterification method presented will enable the fatty acid composition of orchid seeds, and possibly other small seeds, to be determined reliably for studies into seed development, storage and germination.
Adding nitrate to the diet or increasing the concentration of dietary lipid are effective strategies for reducing enteric methane emissions. This study investigated their effect on health and performance of finishing beef cattle. The experiment was a two×two×three factorial design comprising two breeds (CHX, crossbred Charolais; LU, Luing); two basal diets consisting of (g/kg dry matter (DM), forage to concentrate ratios) 520 : 480 (Mixed) or 84 : 916 (Concentrate); and three treatments: (i) control with rapeseed meal as the main protein source replaced with either (ii) calcium nitrate (18 g nitrate/kg diet DM) or (iii) rapeseed cake (RSC, increasing acid hydrolysed ether extract from 25 to 48 g/kg diet DM). Steers (n=84) were allocated to each of the six basal diet×treatments in equal numbers of each breed with feed offered ad libitum. Blood methaemoglobin (MetHb) concentrations (marker for nitrate poisoning) were monitored throughout the study in steers receiving nitrate. After dietary adaptation over 28 days, individual animal intake, performance and feed efficiency were recorded for a test period of 56 days. Blood MetHb concentrations were low and similar up to 14 g nitrate/kg diet DM but increased when nitrate increased to 18 g nitrate/kg diet DM (P<0.001). An interaction between basal diet and day (P<0.001) indicated that MetHb% was consistently greater in Concentrate – than Mixed-fed steers at 18 g nitrate/kg diet DM. Maximum individual MetHb% was 15.4% (of total Hb), which is lower than considered clinically significant (30%). MetHb concentrations for individual steers remained consistent across time. Concentrate-fed steers were more efficient (lower residual feed intake (RFI) values) than Mixed-fed steers (P<0.01), with lower dry matter intake (DMI) (kg/day) (P<0.001) and similar average daily gain (ADG). CHX steers were more efficient (lower RFI; P<0.01) than LU steers with greater ADG (P<0.01), lower DMI (/kg BW; P<0.01) and lower fat depth (P<0.001). ADG, BW or DMI did not differ across dietary treatments (P>0.05). Neither basal diet nor treatment affected carcass quality (P>0.05), but CHX steers achieved a greater killing out proportion (P<0.001) than LU steers. Thus, adding nitrate to the diet or increasing the level of dietary lipid through the use of cold-pressed RSC, did not adversely affect health or performance of finishing beef steers when used within the diets studied.
We examined whether culturing embryos with linoleic acid (LA) in semi-defined medium reduces lipid accumulation and improves cryosurvival after vitrification. Embryos were cultured with LA (100 μM) and a semi-defined medium was used during in vitro culture (IVC), in which the fetal calf serum was substituted by bovine serum albumin (BSA). There was a reduction (P < 0.05) in the embryonic development rate (Control: 25.8% versus LA: 18.5%), but the proposed system was effective in promoting the decrease (P = 0.0130) in the intracellular lipid content (Control: 27.3 ± 0.7 versus LA: 24.6 ± 0.7 arbitrary fluorescence units of embryos stained with the fluorescent dye Nile Red), consequently increasing (P = 0.0490) the embryo survival after 24h of culture post-warming (Control: 50.0% versus LA: 71.7%). The results question the criteria used to evaluate the efficiency of an in vitro production system specifically with relation to the maximum number of blastocysts produced and suggest that might be more appropriate to improve the desired characteristics of embryos generated in accordance with the specific purpose of in vitro embryo production, commercial or scientific. In conclusion, supplying LA to serum-free culture medium was found to adversely affect the rates of embryo development to the blastocyst stage, but significantly reduced embryo lipid accumulation and improved cryopreservation survival.
In this study, the effects of yeast protein hydrolysate (YPH): sucrose proportions in the adult diet of the Ethiopian fruit fly Dacus ciliatus Loew on survival, pupal production, and endogenous lipid and protein contents were investigated. Small populations of the fly were fed diets containing various proportions of YPH and sucrose under low-humidity and high-humidity conditions. The YPH: sucrose proportions ranged from 20 to 50%. We monitored the patterns of survival, pupal production, and individual endogenous protein and lipid loads (only under high-humidity conditions) in flies maintained on various adult diets. The survival patterns of both males and females under high-humidity conditions were inversely proportional to the proportion of YPH in the diet. Mortality of some adult flies was related to the stickiness of the highly hygroscopic adult food mix. By contrast, the survival patterns of males and females maintained under low-humidity conditions were directly proportional to the proportion of YPH in the diet. Apparently, there was no effect of diet type on the number of pupae produced; on the sucrose-only diet, flies produced significantly fewer pupae. Protein content in the flies increased significantly as the proportion of protein in the diet increased, but lipid content was clearly not related to food constitution. Based on these results and recent evidence from studies in other fruit fly species, we concluded that a large amount of protein is deleterious to the fruit flies. Workers in rearing facilities should investigate and tailor different food-delivery systems, e.g. separate dishes for carbohydrates and the food mix, and reduce the amount of YPH used in industrial adult diets.
The muscle lipid, fatty acids and total cholesterol profiles of the spiny cheek grouper, Epinephelus diacanthus, collected from south-west (Arabian Sea) and south-east coasts (Bay of Bengal) of India were evaluated over four years (2008–2011) with regard to three seasons (pre-monsoon, monsoon and post-monsoon). Fatty acids were correlated with chlorophyll-a concentration and sea surface temperature. Lipid content, total polyunsaturated, eicosapentaenoic and docosahexaenoic fatty acids of the samples from the south-west coast showed positive correlation with chlorophyll-a concentration during the monsoon (r2 = 0.93, 0.97, 0.97 and 0.99, respectively). Higher hypocholesterolaemic/hypercholesterolaemic ratio (>1.0) and low atherogenic (<1.2), thrombogenicity (≤0.6) indices make the groupers collected from the coast of the Arabian Sea a valued candidate species for human nutrition. High levels of n-3 fatty acids (>19% during post-monsoon), important in the human diet for their platelet anti-aggregating and blood pressure-reducing properties, for groupers collected from the south-west coast, with higher n-3/n-6 fatty acid ratio (>5.1) proved this species from the coast of the Arabian Sea to be a desirable item in the human diet.
Many sea turtle species are threatened or endangered according to the IUCN Red List. Loggerhead turtles are protected in South African waters, but are migratory, thus may not be so throughout their range. Five individual turtles were caught in the beach-protecting nets off the Indian Ocean coast and provided liver and adipose samples for lipid and fatty acid analysis as part of a long term programme assessing the lipid profiles of southern Indian Ocean marine organisms. Comparing adipose with liver there was little variation in the saturated, monounsaturated and n6 polyunsaturated fatty acids, but increased n3 polyunsaturated fatty acids in adipose compared to liver. These results compared well with data published elsewhere on loggerhead turtles, as well as green turtles, but not other turtle species raised in captivity or other aquatic reptilian species.
Sea food is very rich in lipids. The brown shrimp, Crangon crangon is a most popular and very valuable taxon in the White Sea, in the Mediterranean and in the Black Seas. The aim of this study was to determine the seasonal variations of lipids in C. crangon muscle tissue using gas chromatography–mass spectrometry. The lipids were separated into groups: neutral lipids (triacylglycerols, free fatty acids, sterols) and polar lipids (phospholipids), by high performance liquid chromatography with a laser light-scattering detector. Fatty acids were identified using the GC-MS technique. The mainly fatty acids were 16:0, 18:0 (saturated FAs), 16:1, 18:1 (monounsaturated FAs), 20:4 (ARA), 20:5 (EPA) and 22:6 (DHA). The largest amounts of fatty acids in the muscle were observed in spring; these were the result of collecting food after winter and before reproduction. The muscle lipid content was 32.2 ± 1.8 mg g−1. The summer was the poorest season and the lipid value was 7.7 ±0.4 mg g−1. The levels of muscle neutral lipids (NL) oscillated between 80% (autumn) and 90% (spring). The temperature and salinity has a significant influence on content and profile of fatty acids. This work will help to understand the biology, the seasonal variation in lipid mass, lipid classes content and fatty acids profile in the abdominal muscle of C. crangon.
This review reappraises dietary advice to reduce and replace SFA for the prevention of CVD. In the 1970s, SFA accounted for about 18% UK food energy, by 2001 it had fallen to 13% and continues to be above the <11% target. Compared with carbohydrates, C12–C16 SFA raise serum total cholesterol (TC), LDL-cholesterol (LDL-C) and HDL-cholesterol (HDL-C) without affecting the TC:HDL-C ratio; other SFA have neutral effects on the fasting lipid profile. Replacing 3% dietary SFA with MUFA or PUFA lowers LDL-C by 2% and TC:HDL-C ratio by 0·03. No other specific adverse effects of SFA compared with MUFA on risk CVD factors have been proven. Meta-analyses of prospective cohort studies report the relative risks (95% CI) of high v. low intakes of SFA to be 1·07 (0·96, 1·19) for CHD, 0·81 (0·62, 1·05) for stroke and 1·00 (0·89, 1·11) for CVD mortality and were not statistically significant. Exchanging 5% energy SFA for PUFA or carbohydrates found hazard ratios (95% CI) for CHD death to be 26% (−23, −3) and 4% (−18, 12; NS) lower, respectively. Meta-analysis of randomised controlled trials with clinical endpoints reports mean reductions (95% CI) of 14% (4, 23) in CHD incidence and 6% (−25, 4; NS) in mortality in trials, where SFA was lowered by decreasing and/or modifying dietary fat. In conclusion, SFA intakes are now close to guideline amounts and further reductions may only have a minor impact on CVD.
In the Chausey archipelago, growth of the burrowing bivalve Venus verrucosa
(Mollusca: Veneridae) has been shown to be highly variable between closely
located sites (<1 km). To explain this small-scale spatial variability, we tested the
trophic hypothesis using both fatty acid markers, and carbon and nitrogen stable isotopes
(δ13C and δ15N). Environmental
parameters, including substrate, were also analysed to discriminate their effects on
potential trophic differences. Results of isotopic fractionation and lipid profiles of
water column and digestive gland samples both showed a large contribution of phytoplankton
to the diet of V. verrucosa. More surprisingly, the same results suggest
that Phaeophyceae and Rhodophyceae macroalgae could contribute to the nutrition of
V. verrucosa as dissolved exudates. Whereas site differences were not
observed between the food sources of V. verrucosa, we showed that growth
performance index was correlated to wave height. Thus, we hypothesized that the high local
growth variability could be controlled by the hydrosedimentary dynamics. In addition,
although no significant growth differences were found between intertidal and subtidal
populations, better condition index and more total lipids were found in the digestive
gland of intertidal V. verrucosa, suggesting potential compensatory
In this paper, biochemical and physiological analyses were used to characterize changes associated with mortality event occurred during veliger development of American oyster, Crassostrea virginica. Biochemical analyses included the evaluation of lipid classes, fatty acid composition and total protein content. Larval physiology was evaluated by studying feeding activity, enzymes related to energy metabolism, oxidative stress levels and enzymatic antioxidant defenses. These analyses were complemented by bacterial community analyses as well as by measuring larval oyster performance. We observed that mortality events coincided with (1) strong changes in the surrounding bacterial community; (2) a progressive decrease in feeding activity; (3) higher levels of some lipid classes (free fatty acids, diglycerides, and acetone mobile phospholipids); (4) lower levels of phospholipids and protein; (5) higher contents of non-methylene interrupted dienoic fatty acids (22:2 NMI); (6) a decrease in energy metabolism activity (citrate synthase and cytochrome oxidase activities); (7) a higher oxidative stress (lipid peroxidation level); and (8) an activation of antioxidant defences before mortality (glutathione peroxidase and superoxide dismutase). We hypothesized that mortality emergence was related to higher energy consumption coupled with the progressive decline in feeding activity, lowered energy reserves and a decrease in energy metabolism activity. Thus, the low energy availability limited the efficiency of antioxidant defenses, resulting in a higher oxidative stress.