Quantification of fatty acids in the muscle of Antarctic fish Trematomus bernacchii by gas chromatography-mass spectrometry: Optimization of the analytical methodology

Investigating the effects of microplastics on the metabolism of Trematomus bernacchii from the ross sea (Antarctica)

Microplastic pollution is a growing environmental issue, even reaching remote areas like the Arctic and Antarctic, posing threats to biodiversity and food chains. The present research represents a pioneering endeavor aimed at exploring the relationship between lipids and microplastics in 20 wild specimens of Trematomus bernacchii from the Ross Sea (Antarctica). Fish were grouped in MPs-ingested and MPs-free based on whether they had ingested microplastics. Raman spectroscopy revealed that contaminated fish samples contained from one to three different types of polymeric fibers (1.4 items/specimen, ± = 0.7), specifically, polyester (PES), polypropylene (PP), and polyethylene terephthalate (PET). Gas chromatography-mass spectrometry (GC-MS) and gas chromatography-flame ionization detection (GC-FID) techniques were employed for the study of the lipid composition in term of fatty acids methyl esters (FAMEs). Fifty different FAME compounds were identified and quantified in the lipid fraction extracted from the muscle tissues of the selected fish samples. Polyunsaturated fatty acids (PUFAs) are the most abundant family of fatty acids in T. bernacchii species with eicosapentaenoic (C20:5ω3) and docosahexaenoic (C22:6ω3) acids as main components. In detail, PUFA class accounted for 46.78 ± 6.82% and 44.62 ± 4.86% of the total fatty acid composition in MPs-ingested and MPs-free groups, respectively. The contents of the monounsaturated fatty acids (MUFAs) and saturated fatty acids (SFAs) varied from 27.93% to 31.15% and from 24.23% to 25.05% in MPs-ingested and MPs-free fish samples, respectively. Based on Mann-Whitney test results (p < 0.05), there was no significant difference from a statistical point of view between two groups of fishes. Additionally, nutritional quality indices exhibited comparable values between groups. Results showed that no significant differences were found in the fatty acids distribution between the two groups. This indicates that the lipid composition of wild fish that are naturally exposed to plastic pollution remains unchanged and could still have beneficial effects on human health.

Preclinical determination of wound-healing activity of halibut oil cream in rat model of burn wound

This study investigated the effects of halibut oil cream, containing omega-3 fatty acids, vitamins A and D, and hydroxyproline, on burn wound healing in rats. Acute dermal toxicity tests confirmed its nontoxicity. Wistar rats were divided into five groups: a control, a positive control treated with silver sulfadiazine 1% (SSD), and three groups treated with 3%, 9%, and 27% halibut oil cream Formulation (HBOF). The SSD and HBOF groups showed significant healing improvements compared to the control. Histopathological analysis indicated increased collagen production in the HBOF groups, suggesting halibut oil cream's potential as a topical treatment for burn wounds.

Mercury levels in Merluccius merluccius muscle tissue in the central Mediterranean Sea: Seasonal variation and human health risk

In this study we analysed total mercury (THg) levels in European hake (Merluccius merluccius) - an ecologically and commercially important species throughout the Mediterranean - caught in the northern and central Adriatic Sea. To the best of our knowledge, this is the first study evaluating THg levels in hake fillets in relation to ecological (season) and biological (body size, sex, sexual maturity, lipid content) parameters. THg levels in muscle showed no sex-related differences; in contrast, significant season-related differences were found in females, with higher levels in spring-summer compared with autumn-winter. No season-related differences were seen in males. A significant sex effect was found for body size and sexual maturity. Females showed a correlation between THg level and length, THg being significantly higher in mature compared with immature specimens. No significant sex effect was found for muscle lipid content, because a correlation between THg concentration and tissue lipids was found in both sexes. Since the mean THg concentration found in M. merluccius fillets (0.64 ± 0.29 mg kg^-1 dry weight; range, 0.20-1.53) was consistently under the level set by EU regulations, this study demonstrates that European hake caught in the northern and central Adriatic is safe for human consumption.

Method Development and Validation for Omega-3 Fatty Acids (DHA and EPA) in Fish Using Gas Chromatography with Flame Ionization Detection (GC-FID)

Gas chromatography with flame ionization detection (GC-FID) has often been used to quantify fatty acids in fish. This study validated the common method for determining omega-3 fatty acids (DHA and EPA) in the raw and cooked warm-water fish, selayang, using GC-FID for subsequent evaluation on EPA and DHA retention using the Weibull model. The EPA and DHA were separated using a high-polarity capillary GC HP-88 column (60 m length, 0.25 mm ID, 0.2 μm DF) with a total run time of 45.87 min. The method was validated in linearity, precision, accuracy, specificity and sensitivity based on ICH requirements. In addition, it was found that the method had a high recovery rate (>95%) and good precision (RSD ≤ 2%) with overall RSDs ranging below 0.001% for both omega-3 PUFA. In conclusion, this method identified and quantified fatty acids and omega-3 accurately and precisely and can be used effectively for routine FAME analysis in fish samples.

The impact of seawater warming on fatty acid composition and nutritional quality indices of Trematomus bernacchii from the Antarctic region

There is a growing interest in exploiting Antarctic fisheries for human consumption. However, information on how the nutritional qualities of these resources will respond to the predicted seawater warming in the region for the next century is poor. The present research investigates changes in various nutritional indices of dietary importance (e.g. the ratio polyunsaturated to saturated fatty acids, the atherogenicity index, the thrombogenicity index, the hypo-cholesterolemic to hyper-cholesterolemic index, the health-promoting index, the flesh lipid quality and the ratio omega-3 to omega-6 index) by determining the fatty acid composition in muscle of Trematomus bernacchii (an Antarctic fish species) in its natural habitat (-1.87 °C) and warmer temperatures (0.0, 1.0, 2.0 °C). Comparison of the estimated nutritional indices at -1.87 °C with those at warmer temperatures revealed that seawater warming caused changes in the nutritional indices in the range of -12%<Δ < 30%. The observed changes were not statistically significant and ascribed to biological variability. Therefore, the nutritional values of T. bernacchii muscle were preserved after increasing the temperature of its natural habitat by + 4 °C. The present research is the first report describing the nutritional quality indices for an Antarctic fish species and the consequences of seawater warming on the nutritional value of T. bernacchii.

Physiological responses of Siberian sturgeon (Acipenser baerii) juveniles fed on full-fat insect-based diet in an aquaponic system

Over the last years, the potential use of Black Soldier Fly meal (BSF) as a new and sustainable aquafeed ingredient has been largely explored in several fish species. However, only fragmentary information is available about the use of BSF meal-based diets in sturgeon nutrition. In consideration of a circular economy concept and a more sustainable aquaculture development, the present research represents the first comprehensive multidisciplinary study on the physiological effects of a BSF diet during sturgeon culture in an aquaponic system. Siberian sturgeon (Acipenser baerii) juveniles were fed over a 60-days feeding trial on a control diet (Hi0) and a diet containing 50% of full-fat BSF meal respect to fish meal (Hi50). Physiological responses of fish were investigated using several analytical approaches, such as gas chromatography-mass spectrometry, histology, Fourier Transformed Infrared Spectroscopy (FTIR), microbiome sequencing and Real-time PCR. While aquaponic systems performed optimally during the trial, Hi50 group fish showed lower diet acceptance that resulted in growth and survival reduction, a decrease in hepatic lipids and glycogen content (FTIR), a higher hepatic hsp70.1 gene expression and a worsening in gut histological morphometric parameters. The low feed acceptance showed by Hi50 group sturgeon highlighted the necessity to improve the palatability of BSF-based diet designed for sturgeon culture.

Discrimination between vegetable oil and animal fat by a metabolomics approach using gas chromatography-mass spectrometry combined with chemometrics

Adulteration of olive oil with the other cheap oils and fats plays an important role in economics and has nutritional benefits. In this work, metabolite profiling was performed using gas chromatography-mass spectrometry to identify and quantify animal fat (lard) adulteration in vegetable oil (olive oil). Principal component analysis could correctly identify and clustering olive oil, sunflower oil, sesame oil, lard, and adulterated samples through the changes in their fatty acid methyl esters (FAMEs) profile. A targeted metabolomics method was then optimized and validated through construction of calibration curves of known FAMSs in olive oil and lard. The method was presented high linearity (R2 > 0.96) and good intra and inter day accuracy and precision (79-101 and 86-102% and 2-7 and 3-7, respectively) for determination of FAMEs. Afterwards the absolute concentration and relative percentage of FAMEs were successfully determined in 12 commercial olive oils and 3 lards samples. Methyl myristate, methyl palmitate, methyl oleate, and methyl stearate were selected as discriminant markers to identify and quantify lard adulteration even at a low level of lard (5%w/w), with errors less than 2% in the comparison of the absolute or relative concentrations of FAMEs using several statistical methods. The proposed methodology allowed us to quantify the FAMEs simultaneously and also could predict small amount of lard in the adulterated olive oil samples.

Can Insect-Based Diets Affect Zebrafish (Danio rerio) Reproduction? A Multidisciplinary Study

Black Soldier Fly (BSF) meal is considered an alternative, emerging, and sustainable ingredient for aquafeed formulation. However, results on fish physiological responses are still fragmentary and often controversial, and no data are available on the effect of insect meal-based diets on fish reproduction. On this regard, zebrafish, with its relatively short life cycle, represents an ideal experimental model to explore this topic. In this study, female zebrafish were fed for 12 months on a control diet based on fish meal (FM) and fish oil and two experimental diets with full-fat BSF (Hermetia illucens) prepupae meal inclusion, to replace 25% and 50% of FM (BSF25 and BSF50). All diets were isonitrogenous, isolipidic, and isoenergetic. The effects of these two experimental diets on female's reproduction were investigated through a multidisciplinary approach, including the evaluation of growth, gonadosomatic index, spawned/fertilized eggs and hatching rate, adult female carcass and fertilized egg fatty acid composition, histological analysis of the ovary, spectroscopic macromolecular composition of class IV oocytes, and expression of genes involved in fish lipid metabolism in the liver. Results showed that while fish were perfectly able to cope with a 25% insect meal dietary inclusion, a 50% inclusion level caused the overexpression of genes involved in lipid metabolism, a general reduction in the number of spawned eggs, and differences in the frequency rate of previtellogenic oocytes, class III, IV, oocytes and postovulatory follicles and atretic oocytes, in the macromolecular composition of class IV oocytes, and in the fatty acid composition of the fertilized eggs, respect to control and 25% group.

Zebrafish (Danio rerio) physiological and behavioural responses to insect-based diets: a multidisciplinary approach

Black Soldier Fly (BSF) meal is considered as an alternative, emerging and sustainable ingredient for aquafeed production. However, results on fish physiological responses are still fragmentary and often controversial, while no studies are available on fish behavior in response to these new diets. The present work represents the first comprehensive multidisciplinary study aimed to investigate zebrafish physiological and behavioural responses to BSF-based diets. Five experimental diets characterized by increasing inclusion levels (0, 25, 50, 75 and 100% respect to fish meal) of full fat BSF prepupae meal were tested during a 2-months feeding trial. Prepupae were cultured on coffee silverskin growth substrate enriched with a 10% Schizochytrium sp. to improve insects’ fatty acids profile. The responses of zebrafish were assayed through biometric, histological, gas chromatographic, microbiological, spectroscopic, molecular and behavioural analyses. Results evidenced that BSF-based diets affected fish fatty acid composition, while behavioural tests did not show differences among groups. Specifically, a 50% BSF inclusion level diet represented the best compromise between ingredient sustainability and proper fish growth and welfare. Fish fed with higher BSF inclusions (75 and 100%) showed hepatic steatosis, microbiota modification, higher lipid content, fatty acid modification and higher expression of immune response markers.

Effects of biological factors and seasonality on the level of polycyclic aromatic hydrocarbons in red mullet (Mullus barbatus)

This study evaluates the effects of biological factors of fish and seasonality on Polycyclic Aromatic Hydrocarbon (PAH) accumulation in red mullet (Mullus barbatus) tissue. Specimens were collected monthly with a bottom trawl net in an offshore fishing ground in the Northern and Central Adriatic Sea (Geographical Sub Area 17) throughout 2016. The edible fillets of 380 individuals were analyzed for the concentrations of individual PAH, total PAH, and low, medium and high molecular weight (MW) PAHs. PAH bioaccumulation was related to their physicochemical characteristics (MW, and logarithm of the octanol-water partition coefficient, log K_ow), some biological parameters of fish (body size, age, sex, reproductive stage and total lipid content), and catch season. The PAH bioaccumulation pattern and the effects of the different factors varied according to PAH MW. The heavier (medium and high MW) PAHs showed higher levels in winter-autumn and in pre-spawners compared with spawners and post-spawners. Our findings suggest that an important detoxification mechanism, albeit limited to the heavier PAHs, acts in the spawning and post-spawning stage. Low MW PAHs appeared to be unaffected by reproductive stage, lipid content and seasonality. Reproductive stage and seasonality seem to play an important role in the accumulation of heavier PAH, whereas total lipid content and age seem to exert a limited influence, and body size no effect at all.

Reproductive Biology and Ecology of the Green Mussel Perna viridis: A Multidisciplinary Approach

A multidisciplinary approach was applied to explore deeper knowledge about the reproductive biology and ecology of the green mussel (Perna viridis) by interlinking among ecological factors, ingested gut plankton, gonad fatty acid profile, and reproductive traits. Mussels were collected throughout the year from the coastal region of the Bay of Bengal of Bangladesh, and the histological analysis of 242 mussels revealed five stages of gametogenesis with an annual spawning season from January to April. The gonadosomatic index showed a strong correlation with the water quality parameters, ingested gut plankton groups, and gonadal fatty acids, and also displayed prominent effects of seasonality. In all datasets, we performed principal component analysis in which the first two principal components showed that seasonality explained >65% of the variability, and the multivariate spaces of seasonality corresponded to the gonad development. High salinity, nutrients, chlorophyll a, and plankton abundance in the water column were positively correlated with gonad development and the spawning of mussels. During the development stage, mussel ingested more plankton, particularly Bacillariophyceae and Pyrrophyceae, which were an important source of increased n-3 polyunsaturated fatty acids content in gonads. Furthermore, gonads accumulated more lipids and saturated fatty acids during the mature and spawning stages, which were probably utilized during embryogenesis and early larval development as energy sources and constituents of the cell membrane. This research provides a model toward a better understanding of reproductive biological traits and how these traits are interrelated with the surrounding environmental variables of the green mussel, which would be helpful in marine aquaculture and the sustainable exploitation of the fishery resources.

Modeling the influence of time and temperature on the levels of fatty acids in the liver of Antarctic fish Trematomus bernacchii

Antarctic fish (Trematomus bernacchii) are an ideal group for studying the effect of ocean warming on vital physiological and biochemical mechanisms of adaptation, including changes in the fatty acid composition to higher heat tolerance in the sub-zero waters of the Southern Ocean. Despite the awareness of the impact of ocean warming on marine life, bioclimatic models describing the effect of temperature and time on fatty acid levels in marine species have not been considered yet. The objective of the present study was to investigate changes in the concentrations of fatty acids in liver from T. bernacchii in response to an increase in temperature in the Antarctic region. Changes in the concentrations of fatty acids in liver from T. bernacchii were observed after varying simultaneously and systematically the temperature and time. The fatty acid profiles were determined by gas chromatography prior to acclimation (− 1.8 °C) and after acclimation (0.0, 1.0, and 2.0 °C) at different times (1, 5, and 10 days). The observed changes were graphically visualized by expressing the fatty acid concentration in absolute units (mg g−1) as a function of the temperature and time using polynomial models. Major changes in fatty acid composition were observed at day 1 of exposition at all temperatures. At day 5, the fish seem to tolerate the new temperature condition. The concentrations of saturated fatty acids were almost constant throughout the various conditions. The concentrations of monounsaturated fatty acids (in particular 18:1n − 9) decrease at day 1 for all temperatures. In contrast, there was an increase in the concentrations of polyunsaturated fatty acids (in particular 20:5n − 3 and 22:6n − 3) with increasing temperatures after 1, 5, and 10 days of exposure. The proposed models were in agreement with reported studies on polar and temperate fish, indicating possibly similar adaptation mechanisms for teleost to cope with global warming.

A six-months study on Black Soldier Fly (Hermetia illucens) based diets in zebrafish

Intensive fish farming relies on the use of feeds based on fish meal and oil as optimal ingredients; however, further development of the aquaculture sector needs new, nutritious and sustainable ingredients. According to the concept of circular economy, insects represent good candidates as aquafeed ingredients since they can be cultured through environmental-friendly, cost-effective farming processes, on by-products/wastes, and many studies have recently been published about their inclusion in fish feed. However, information about the physiological effects of insect-based diets over the whole life cycle of fish is presently missing. At this regard, the present study investigated, for the first time, the effects of Black Soldier Fly based diets (25 and 50% fish meal substitution) administration for a six months period in zebrafish (Danio rerio), from larvae to adults. A multidisciplinary approach, including biometric, biochemical, histological, spectroscopic and molecular analyses was applied. Aside a general reduction in fish growth and lipid steatosis, six-months feeding on Black Soldier Fly based diets did not show major negative effects on zebrafish. Gut histological analysis on intestine samples did not show signs of inflammation and both stress markers and immune response markers did not show significant differences among the experimental groups.

Rapid and direct determination of fatty acids and glycerides profiles in Schisandra chinensis oil by using UPLC-Q/TOF-MSE

Fatty acids and glycerides are globally accepted quality and nutrition indicators of oils. Schisandra chinensis (S. chinensis) is a good functional oil source, with an oil content of 10-50% (dry weight). In this study, the UPLC-Q/TOF-MS^E technique was developed to profile FFA and glycerides in the S. chinensis oils directly. The results showed that all of the 36 FFA calibration equations of the mixture standard had good linear relationships (R² > 0.99). The limit of detection for the tested compounds ranged from 0.0001 to 0.0200 μg/mL, while the limit of quantification ranged from 0.0005 to 0.1300 μg/mL. In total, seventeen FFAs, six diglycerides and 20 triglycerides were identified. Linoleic, oleic, stearic and palmitic acids were the most abundant FFAs in the S. chinensis oils. It was also found that S. chinensis oil is rich in the L-L, L-L-L, O-L-L and O-L-O glycerides. These results will be helpful for the use of this technique in physicochemical evaluation and for further application development.

Polycyclic aromatic hydrocarbon (PAH) accumulation in different common sole (Solea solea) tissues from the North Adriatic Sea peculiar impacted area

This study extends our knowledge of the bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) in marine organisms and investigates its possible determinants. PAH levels were measured in Solea solea tissue and in marine sediments collected from three areas of the northern Adriatic Sea characterized by different anthropic impacts (Venetian Lagoon, Po Delta, and fishing grounds off Chioggia). The possibility of differential PAH bioaccumulation in different tissues (muscle, liver and gills) was investigated by seeking relationships between mean individual and total PAH concentrations in tissue and sediment samples, the physicochemical properties of PAHs (rings and K_ow), and some key biological variables (lipid content of tissues, body size, habitat). The present study demonstrated that the lipid content might not be the only determinant of PAH bioaccumulation in common sole tissues. The habitat characteristics, the tissue types and some physicochemical properties of compounds were closely related to PAH bioaccumulation.

Heat shock influences the fatty acid composition of the muscle of the Antarctic fish Trematomus bernacchii

In the Ross Sea region (average temperature of -1.87 °C), shelf water warming up to +0.8-+1.4 °C is predicted by 2200, so there is an urgent need to understand how organisms can respond to rising temperatures. In this study, we analyzed the effect of a heat shock on the fatty acid (FAs) composition of muscle of the Antarctic teleost Trematomus bernacchii, caught in Terra Nova Bay (Ross Sea), and held in fish tanks at 0, +1 or +2 °C, for 1, 5 and 10 days. In general, heat shock produced, beyond a reduction in total lipid content correlated to the temperature, an increase in the percentage of saturated FAs, and a decrease in mono-unsaturated FAs; however, the level of poly-unsaturated FAs did not seem to directly correlate with temperature. Principal component analysis indicated that both temperature and exposure time affect the composition of FAs in the muscle probably through an alteration of the metabolic pathways of FAs. In this study, we demonstrated that T. bernacchii was capable to rapidly acclimatize to a heat shock. This study contributes to increasing knowledge on the effect of temperature on the lipid composition of T. bernacchii and is complementary to previous studies on the gene expression and biochemistry of this species face multiple stressors.

Partial Dietary Inclusion of Hermetia illucens (Black Soldier Fly) Full-Fat Prepupae in Zebrafish Feed: Biometric, Histological, Biochemical, and Molecular Implications

Due to minimal environmental impact, compared to most conventional feed commodities, insects deserve a growing attention as candidate ingredients for aquafeeds. This study tested, for the first time during zebrafish larval rearing, the effects of an increasing replacement (0%-25%-50%) of fish meal by black soldier fly (BSF) full-fat prepupae meal. All diets were formulated to be isonitrogenous and isolipidic. A multidisciplinary approach, including biometrics, histology, gas chromatography-mass spectrometry, and molecular analyses, was applied to better understand the biological responses of larval zebrafish to the different partial inclusions of BSF in the feed. Generally, results are promising, but a 50% of BSF meal inclusion in the diet affected both lipid composition and accumulation in the larvae.

Determination of Cyclopropane Fatty Acids in Food of Animal Origin by 1H NMR

Cyclopropane fatty acids (CPFAs) are unusual fatty acids of microbial origin, recently detected in milk and dairy products. CPFAs have been demonstrated to be interesting molecular markers for authentication of dairy products obtained without ensiled feeds. Moreover, they can also be recognized as a new secondary component of human diet. Information is lacking on the presence of cyclic fatty acids in other food sources. Cyclopropane fatty acids have been detected by GC-MS analysis in cheese and other animal fats in concentration ranging from 200 to 1000 mg/kg fat, but in some cases, the complex fatty acid profile and the possible presence of interfering peaks make the separation not straightforward and the quantification uneasy. Therefore, a new reliable ¹H NMR method was developed to detect and measure CPFA content in different foods of animal origin, based on the detection of the characteristic signals of cyclopropane ring. The ¹H NMR (600 MHz) method showed detection limits comparable with those of full scan GC-MS, and it allowed the identification and quantitation of the cyclopropane fatty acids in different foods.

Rearing Zebrafish on Black Soldier Fly (Hermetia illucens): Biometric, Histological, Spectroscopic, Biochemical, and Molecular Implications

A desirable goal of the aquaculture sector is to replace most of fish meal and fish oil with more sustainable, cost-effective, and environmental friendly ingredients ensuring fish health and welfare standards. Due to minimal environmental impact, compared with most conventional feed commodities, insects deserve a growing attention as candidate ingredients for aquafeeds. The present study investigated, for the first time, the possible application of a 100% insect diet in zebrafish larval rearing. Through a multidisciplinary approach, the major biological responses of fish to the new diets were assessed. Results of biometry, fatty acid composition, expression of genes involved in fish growth, stress response, lipid metabolism, chitinolytic activity, gut inflammation, and liver macromolecular composition suggested a possible application of insect larvae for zebrafish larval rearing. However, further studies are necessary to better understand the use of this insect species in the rearing of fish.

A multidisciplinary approach to study the reproductive biology of wild prawns

This work aims to provide deeper knowledge on reproductive biology of P. kerathurus in a multidisciplinary way. Upon 789 examined females, 285 were found inseminated. The logistic equation enabled to estimate the size at first maturity at 30.7 mm CL for female. The Gono-Somatic Index (GSI) showed a pronounced seasonality, ranged from 0.80 ± 0.34 to 11.24 ± 5.72. Histological analysis highlighted five stages of ovarian development. Gonadal fatty acids analysis performed with gas chromatograph evidenced a pronounced seasonal variation; total lipids varied from 1.7% dry weight (dw) in Winter, to 7.2% dw in Summer. For the first time, a chemometric approach (Principal Component Analysis) was applied to relate GSI with total lipid content and fatty acid composition of gonads. The first two components (PC1 and PC2) showed that seasonality explained about 84% of the variability of all data set. In particular, in the period February-May, lipids were characterized by high PUFAs content, that were probably utilized during embryogenesis as energy source and as constituent of the cell membranes. During the summer season, gonads accumulated saturated FAs, that will be used during embryogenesis and early larval stages, while in the cold season total lipids decreased drastically and the gonad reached a quiescent state.