Binding and distribution regularity of water molecules in high-moisture textured Antarctic krill (Euphausia superba) meat.

High-moisture extrusion technique with the advantage of high efficiency and low energy consumption is a promising strategy for processing Antarctic krill meat. Consequently, this study aimed to prepare high-moisture textured Antarctic krill meat (HMTAKM) with a rich fiber structure at different water contents (53 %, 57 %, and 61 %) and to reveal the binding and distribution regularity of water molecules, which is closely related to the fiber structure of HMTAKM and has been less studied. The hydrogen-bond network results indicated the presence of at least two or more types of water molecules with different hydrogen bonds. Increasing the water content of HMTAKM promoted the formation of hydrogen bonds between the water molecules and protein molecules, leading to the transition of the ß-sheet to the α-helix. These findings offer a novel viable processing technique for Antarctic krill and a new understanding of the fiber formation of high-moisture textured proteins.

Population changes in a Southern Ocean krill predator point towards regional Antarctic sea ice declines.

While foraging, marine predators integrate information about the environment often across wide-ranging oceanic foraging grounds and reflect these in population parameters. One such species, the southern right whale (Eubalaena australis; SRW) has shown alterations to foraging behaviour, declines in body condition, and reduced reproductive rates after 2009 in the South African population. As capital breeders, these changes suggest decreased availability of their main prey at high-latitudes, Antarctic krill (Euphausia superba). This study analysed environmental factors affecting prey availability for this population over the past 40 years, finding a notable southward contraction in sea ice, a 15-30% decline in sea ice concentration, and a more than two-fold increase in primary production metrics after 2008. These environmental conditions are less supportive of Antarctic krill recruitment in known SRW foraging grounds. Additionally, marginal ice zone, sea ice concentration and two primary production metrics were determined to be either regionally significant or marginally significant predictors of calving interval length when analysed using a linear model. Findings highlight the vulnerability of recovering baleen whale populations to climate change and show how capital breeders serve as sentinels of ecosystem changes in regions that are difficult or costly to study.

Comparison of Dietary Supplementation with Krill Oil, Fish Oil, and Astaxanthin on an Experimental Ethanol-Induced Gastric Ulcer Model: A Biochemical and Histological Study.

BACKGROUND/OBJECTIVES: Despite advances in ulcer treatment research, the search for new, safe, and effective strategies for preventing and treating ulcer diseases persists. METHODS: In this study, the protective effects of dietary supplementation with krill oil (KO), fish oil (FO), and astaxanthin (ASX) on an ethanol-induced gastric ulcer model were compared during biochemical and histological observations. Sprague-Dawley (n = 64) rats randomly divided into four groups-normal control (vehicle), KO, FO, and ASX groups-received the supplements via the orogastric route at a rate of 2.5% (v/w) of their daily feed consumption for 4 weeks. Then, ulcer induction was performed with ethanol. RESULTS: The ulcer group showed increased levels of malondialdehyde (MDA), chemiluminescence (CL), and myeloperoxidase (MPO) activity and decreased levels of glutathione in the gastric tissues. While KO, FO, and ASX supplementation decreased chemiluminescence levels in the ulcer group, only ASX supplementation decreased MDA levels and MPO activity. CONCLUSIONS: In conclusion, supplementation with KO or FO has a similar protective effect against ethanol-induced ulcer damage, as it inhibits ROS formation and reduces lipid peroxidation. However, ASX supplementation has a higher protective effect than KO or FO supplementations against experimental ethanol-induced gastric lesions in rats, as it inhibits ROS formation and reduces neutrophil infiltration and lipid peroxidation.

Availability to predators and a size structure of the Antarctic krill Euphausia superba in the 48.1 CCAMLR subarea.

The Antarctic krill Euphausia superba is a key species in Antarctic waters, mainly because it is a major component of the diet of dominant predators, including penguins. It is also a marine living resource that is commercially harvested. Since 2000, krill fishing has become more concentrated. On the basis of several years of data, it has been reported that up to 57% of the krill fishery harvests occur in the Bransfield Strait area. The distribution of krill in the Southern Ocean is not well described. Studies that compare the size of krill caught by commercial vessels with that recorded in the diet of predators are even rarer. The main objectives of this study were to assess the spatial diversity in the size and putative age of krill in the CCAMLR subarea 48.1, to investigate the spatial availability of krill and its size and age structure, and to assess whether the diet of Pygoscelis penguins reflects the size structure of krill present in the environment. The results implied that the size and age structure of the krill population were similar throughout the Bransfield Strait during the study period, although those in the eastern and southern parts of the strait and the Brabant Island region were the most similar. The Livingston Island and Drake Passage areas were clearly distinguishable from the above regions, where larger and therefore older krill were recorded. All Pygoscelis penguin species showed size preferences for consumed krill; therefore, their diet is likely not a reliable indicator of the size of krill in the environment. Krill that had not yet reached sexual maturity, and thus not yet started reproducing were commercially caught in the Bransfield Strait during the investigated years.

Whale recovery and the emerging human-wildlife conflict over Antarctic krill.

The Southern Ocean ecosystem has undergone extensive changes in the past two centuries driven by industrial sealing and whaling, climate change and commercial fishing. However, following the end of commercial whaling, some populations of whales in this region are recovering. Baleen whales are reliant on Antarctic krill, which is also the largest Southern Ocean fishery. Since 1993, krill catch has increased fourfold, buoyed by nutritional supplement and aquaculture industries. In this Perspective, we approximate baleen whale consumption of Antarctic krill before and after whaling to examine if the ecosystem can support both humans and whales as krill predators. Our back-of-the-envelope calculations suggest that current krill biomass cannot support both an expanding krill fishery and the recovery of whale populations to pre-whaling sizes, highlighting an emerging human-wildlife conflict. We then provide recommendations for enhancing sustainability in this region by reducing encounters with whales and bolstering the krill population.

Exome capture of Antarctic krill (Euphausia superba) for cost effective genotyping and population genetics with historical collections.

Antarctic krill (Euphausia superba Dana) is a keystone species in the Southern Ocean ecosystem, with ecological and commercial significance. However, its vulnerability to climate change requires an urgent investigation of its adaptive potential to future environmental conditions. Historical museum collections of krill from the early 20th century represent an ideal opportunity to investigate how krill have changed over time due to predation, fishing and climate change. However, there is currently no cost-effective method for implementing population scale collection genomics for krill given its genome size (48 Gbp). Here, we assessed the utility of two inexpensive methods for population genetics using historical krill samples, specifically low-coverage shotgun sequencing (i.e. 'genome-skimming') and exome capture. Two full-length transcriptomes were generated and used to identify 166 putative gene targets for exome capture bait design. A total of 20 historical krill samples were sequenced using shotgun and exome capture. Mitochondrial and nuclear ribosomal sequences were assembled from both low-coverage shotgun and off-target of exome capture data demonstrating that endogenous DNA sequences could be assembled from historical collections. Although, mitochondrial and ribosomal sequences are variable across individuals from different populations, phylogenetic analysis does not identify any population structure. We find exome capture provides approximately 4500-fold enrichment of sequencing targeted genes, suggesting this approach can generate the sequencing depth required to call identify a significant number of variants. Unlocking historical collections for genomic analyses using exome capture, will provide valuable insights into past and present biodiversity, resilience and adaptability of krill populations to climate change.

Influence of lipid oxidation on the digestive efficiency of Antarctic krill oil: insights from a simulated gastrointestinal digestion model.

Lipid oxidation profoundly impacts its digestibility, a topic that has been predominantly investigated in triglyceride (TAG)-based dietary lipids. However, there is a dearth of similar research on lipids with diverse classes, such as Antarctic krill oil (AKO), which encompasses a spectrum of lipids including glycerides and phospholipids. This study aimed to elucidate the influence of lipid oxidation on the digestibility of AKO through a simulated gastrointestinal digestion (SGID) model. Post-SGID, AKO exhibited oxidative changes, evidenced by an escalation in peroxide value, conjugated diene value, thiobarbituric acid reactive substances and Schiff base formation. Concurrently, the digestibility of oxidized AKO was found to be inferior to that of fresh AKO, as indicated by a diminished hydrolysis degree of TAGs and phosphatidylcholine (PC), along with a reduced release of free fatty acids. Furthermore, co-digestion with tea polyphenol palmitate was observed to mitigate the oxidation of AKO and the digestion of PC during the SGID, while exerting no significant impact on TAG digestion. Notably, the emulsification capacity of oxidized AKO in a simulated intestinal fluid (without pancreatin and phospholipase A2) was also found to be inferior to that of its fresh counterpart. These findings suggest that lipid oxidation may adversely affect the emulsification capacity of AKO under simulated intestinal conditions, thereby leading to a decrement in digestibility.

Analysis of Fatty Acid Compositions and Acid Values of Krill Oil Supplementary Products from the Korean Market.

In order to provide the qualitative data for the 20 commercially available krill oil supplementary products, the levels of omega-3 polyunsaturated fatty acids (PUFA) such as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), fatty acid compositions, and chemical indices, including acid values, of the supplements, were determined. The acid values ranged from 7.4 to 43.7 mg of potassium hydroxide (KOH)/ g of oil. The relative percentages of EPA and DHA in the oils ranged from 14.2 to 34.8 % (w/w). Although all 20 krill oil supplements used 100% krill oil as raw material, the fatty acid composition of 4 samples differed from typical krill oil in terms of the content of myristic acid (C14:0), palmitic acid (C16:0), palmitoleic acid (C16:1), linoleic acid (C18:2, n-6), and eicosenoic acid (C20:1, n-9). Accordingly, the Ministry of Food and Drug Safety recently standardized linoleic acid (3% or less) and myristic acid (5-13%) as part of the fatty acid components of krill oil. This study provides a reference for analyzing the chemical and nutritional properties and evaluating the adulteration of krill oil supplements in the Korean market.

Enrichment characteristics of microplastics in Antarctic benthic and pelagic fish and krill near the Antarctic Peninsula.

Global microplastic pollution has garnered widespread attention from researchers both domestically and internationally. However, compared to other regions worldwide, little is known about microplastic pollution in the marine ecosystems of the Antarctic region. This study investigated the abundance and characteristics of microplastics (MPs) in the gills and intestines of 15 species of Antarctic fish and Antarctic krill (Euphausia superba). The results indicate that the abundance of MPs in Antarctic fish and E. superba ranged from 0.625 to 2.0 items/individual and 0.17 to 0.27 items/individual, with mean abundances of 0.93 ± 0.96 items/individual and 0.23 ± 0.44 items/individual, respectively. Antarctic fish ingested significantly more MPs than E. superba. There was no significant difference in the abundance of MPs between the gills and intestines of Antarctic fish. However, the quantity of pellet-shaped MPs in the gills was significantly higher than in the intestines. The depth of fish habitat influenced the quantity and size of MPs in their bodies, with benthic fish ingesting significantly fewer MPs than pelagic fish. Pelagic fish ingested significantly more MPs sized 1-5 mm than benthic fish. Additionally, analysis of the characteristics of MPs revealed that fiber-shaped MPs were predominant in shape, with sizes generally smaller than 0.25 mm and 0.25-0.5 mm. The predominant colors of MPs were transparent, red, and black, while the main materials were polypropylene (PP), polystyrene (PS), polyamide (PA), and polyvinyl chloride (PVC). Compared to organisms from other regions, the levels of MPs in Antarctic fish and E. superba were relatively low. This study contributes to a better understanding of the extent of MP pollution in Antarctic fish and E. superba, aiding human efforts to mitigate its impact on the environment.

Typical structural characteristics and hepatoprotective effects of novel high Fischer ratio oligopeptides from Antarctic krill on acute alcoholic liver injury.

High Fischer ratio oligopeptides derived from Antarctic krill (HFOPs-AK) were screened, and their hepatoprotective effects and potential mechanisms were investigated. Herein, HFOPs-AK, with a Fischer ratio of 29 g/g (40.22 mol/mol) (MW < 1000 Da), were prepared via two-step enzymatic hydrolysis using chymotrypsin and flavourzyme and aromatic amino acid removal. Seventy-eight characteristic peptides were identified from HFOPs-AK through UHPLC-Q/TOF, with peptides containing Leu, Val, or Ile accounting for 79%. High hepatoprotective peptides were purified using GFC and RP-HPLC and identified as SDELGW and LLGWDDM. Furthermore, a murine model of acute liver injury induced by alcohol was successfully established. It was demonstrated that the oral administration of HFOPs-AK (800 mg per kg bw per d) remarkably increased the contents of ADH and ALDH compared with the model group, reaching 3.40 and 5.10 U mg-1 prot, respectively. Further, it was revealed that HFOPs-AK could effectively mitigate hepatic oxidative stress by increasing the levels of GSH-Px (p < 0.01) and decreasing the level of MDA (p < 0.05). Additionally, HFOPs-AK (800 mg per kg bw per d) attenuated liver inflammation by down-regulating the mRNA levels of TNF-α, IL-1ß, and IL-6 by 40.45%, 38.48%, and 35.83%, respectively. Therefore, HFOPs-AK may have the potential as a new nutritional supplement for the treatment of alcoholic liver injury.

Krill oil supplementation for knee pain: a systematic review and meta-analysis with trial sequential analysis of randomized controlled trials.

INTRODUCTION: Knee pain is a major cause of disability worldwide, particularly among the elderly. Current treatments, including nonsteroidal anti-inflammatory drugs and analgesics, often lead to adverse effects. Krill oil is being explored as a potential alternative, however its efficacy in managing knee symptoms remains unclear. METHODS: MEDLINE, Embase, and Cochrane databases were searched until May 2024 for studies comparing krill oil and placebo in knee pain patients. Endpoints included knee pain, stiffness, physical function, and lipid profiles (HDL-C, LDL-C, triglycerides, and total cholesterol). A restricted maximum likelihood random-effects model with standardized mean differences (SMD) and 95% confidence intervals (CI) was used. A trial sequential analysis was conducted to evaluate further research implications. RESULTS: We included five trials with 700 patients using krill oil for knee pain. Results showed no significant difference between krill oil and placebo for knee pain, knee stiffness, and lipid profiles. However, krill oil demonstrated a significant small effect in improving knee physical function (SMD -0.24, 95% CI [-0.41; -0.08], I2 = 0%).Trial sequential analysis provided certainty that krill oil enhances knee physical function compared to placebo and indicated no improvement in knee pain, but the findings for knee stiffness need to be confirmed by further research. CONCLUSION: This study found that krill oil supplementation did not significantly improve knee pain, stiffness, or lipid profile, although it may help knee physical function. Based on these findings, krill oil supplementation is not yet justified for knee pain.

Ecological genomics in the Northern krill uncovers loci for local adaptation across ocean basins.

Krill are vital as food for many marine animals but also impacted by global warming. To learn how they and other zooplankton may adapt to a warmer world we studied local adaptation in the widespread Northern krill (Meganyctiphanes norvegica). We assemble and characterize its large genome and compare genome-scale variation among 74 specimens from the colder Atlantic Ocean and warmer Mediterranean Sea. The 19 Gb genome likely evolved through proliferation of retrotransposons, now targeted for inactivation by extensive DNA methylation, and contains many duplicated genes associated with molting and vision. Analysis of 760 million SNPs indicates extensive homogenizing gene-flow among populations. Nevertheless, we detect signatures of adaptive divergence across hundreds of genes, implicated in photoreception, circadian regulation, reproduction and thermal tolerance, indicating polygenic adaptation to light and temperature. The top gene candidate for ecological adaptation was nrf-6, a lipid transporter with a Mediterranean variant that may contribute to early spring reproduction. Such variation could become increasingly important for fitness in Atlantic stocks. Our study underscores the widespread but uneven distribution of adaptive variation, necessitating characterization of genetic variation among natural zooplankton populations to understand their adaptive potential, predict risks and support ocean conservation in the face of climate change.

Mechanism of discoloration of Antarctic krill oil upon storage: A study based on model systems.

The reddish-orange color of Antarctic krill oil fades during storage, and the mechanism remains unclear. Model systems containing different combinations of astaxanthin (ASTA), phosphatidylethanolamine (PE), and tocopherol were subjected to accelerated storage. Among all groups containing ASTA, only the ones with added PE showed significant fading. Meanwhile, the specific UV-visible absorption (A470 and A495) showed a similar trend. Peroxide value and thiobarbituric acid reactive substances increased during storage, while ASTA and PE contents decreased. Correlation analysis suggested that oxidized PE promoted fading by accelerating the transformation of ASTA. PE content exceeded the critical micelle concentration (1µg/g) indicating the formation of reverse micelles. Molecular docking analysis indicated that PE also interacted with ASTA in an anchor-like manner. Therefore, it is speculated that amphiphilic ASTA is more readily distributed at the oil-water interface of reverse micelles and captured by oxidized PE, which facilitates oxidation transfer, leading to ASTA oxidation and color fading.

Different stages of flavor variations among canned Antarctic krill (Euphausia superba): Based on GC-IMS and PLS-DA.

The aim of the present study was to explore changes in the profile of volatile compounds (VCs) in canned Antarctic krill (Euphausia superba) at different processing stages using partial least squares discriminant analysis (PLS-DA) and gas chromatography-mass spectrometry (GC-IMS). A total of 43 VCs were detected using GC-IMS in all krill meat samples, which included mainly alcohols, aldehydes, ketones, esters, and furans. Considering the different processing stages, the highest variation in VCs and the highest VC content were observed in krill meat which underwent both blanching and salt addition. PLS-DA further revealed flavor differences in canned Antarctic krill meat at different processing stages, with octanal, 2-hexanol, 2-octane, 2,3,5-trimethyl pyrazine, and cis-3-hexanol as the main contributors to observed differences in VC profiles. These findings contribute to the production of high-quality canned krill meat, enhancing its flavor quality and providing a feasible theoretical basis for future krill meat pretreatment and industry development.

A method to estimate prey density from single-camera images: A case study with chinstrap penguins and Antarctic krill.

Estimating the densities of marine prey observed in animal-borne video loggers when encountered by foraging predators represents an important challenge for understanding predator-prey interactions in the marine environment. We used video images collected during the foraging trip of one chinstrap penguin (Pygoscelis antarcticus) from Cape Shirreff, Livingston Island, Antarctica to develop a novel approach for estimating the density of Antarctic krill (Euphausia superba) encountered during foraging activities. Using the open-source Video and Image Analytics for a Marine Environment (VIAME), we trained a neural network model to identify video frames containing krill. Our image classifier has an overall accuracy of 73%, with a positive predictive value of 83% for prediction of frames containing krill. We then developed a method to estimate the volume of water imaged, thus the density (N·m-3) of krill, in the 2-dimensional images. The method is based on the maximum range from the camera where krill remain visibly resolvable and assumes that mean krill length is known, and that the distribution of orientation angles of krill is uniform. From 1,932 images identified as containing krill, we manually identified a subset of 124 images from across the video record that contained resolvable and unresolvable krill necessary to estimate the resolvable range and imaged volume for the video sensor. Krill swarm density encountered by the penguins ranged from 2 to 307 krill·m-3 and mean density of krill was 48 krill·m-3 (sd = 61 krill·m-3). Mean krill biomass density was 25 g·m-3. Our frame-level image classifier model and krill density estimation method provide a new approach to efficiently process video-logger data and estimate krill density from 2D imagery, providing key information on prey aggregations that may affect predator foraging performance. The approach should be directly applicable to other marine predators feeding on aggregations of prey.

Correction of omega-3 fatty acid deficiency and improvement in disease activity in patients with systemic lupus erythematosus treated with krill oil concentrate: a multicentre, randomised, double-blind, placebo-controlled trial.

OBJECTIVE: Omega-3 polyunsaturated fatty acids (PUFAs) play a critical role in regulating inflammation and lipid metabolism. This study sought to ascertain the frequency of omega-3 deficiency in patients with SLE and investigate whether supplementation with krill oil concentrate (KOC) could replenish omega-3 levels and decrease SLE disease activity. METHODS: A multicentre, randomised, double-blind, placebo-controlled trial was conducted in adult patients with active SLE. Eligible patients were randomised to receive 4 g/day KOC or placebo (vegetable oil mixture) for the first 24 weeks, and thereafter patients could opt to enter an open-label extension. The primary end point was improvement of the red blood cell Omega-3 Index from baseline to week 24. Changes in clinical features, including SLE Disease Activity Index 2000 (SLEDAI-2K) disease activity scores, were also monitored. RESULTS: Seventy-eight patients met eligibility criteria and were randomised to a treatment group (n=39 per group). The baseline Omega-3 Index in the total SLE cohort was a mean 4.43% (±SD 1.04%). After 4 weeks of KOC treatment, the Omega-3 Index rapidly increased to 7.17%±1.48% (n=38) and after 24 weeks to 8.05%±1.79% (n=25) (each p<0.001 vs baseline), whereas no significant change from baseline was noted in patients receiving placebo. Increases in the Omega-3 Index in KOC-treated patients persisted through week 48. After patients switched from placebo to KOC at 24 weeks, the mean Omega-3 Index showed a rapid and significant increase (from 4.63%±1.39% at week 24 (n=26) to 7.50%±1.75% at week 48 (n=12); p<0.001). Although there were no changes in disease activity in the study population overall, SLEDAI-2K scores decreased significantly in the KOC group during the 24-week randomised period among those who had high disease activity at baseline (SLEDAI-2K ≥9) (p=0.04, p=0.02 and p=0.01 vs placebo at 4, 8 and 16 weeks, respectively; n=9 per group). KOC was well-tolerated, with no significant safety concerns. CONCLUSION: KOC corrected omega-3 deficiency in patients with SLE. Supplementation with KOC was safe and decreased disease activity in those with more active disease. These findings warrant further evaluation of omega-3 fatty acid supplementation with KOC in the management of SLE. TRIAL REGISTRATION NUMBER: NCT03626311.

A new Activity Monitor for Aquatic Zooplankter (AMAZE) allows the recording of swimming activity in wild-caught Antarctic krill (Euphausia superba).

Antarctic krill (Euphausia superba, hereafter krill) is a pelagic living crustacean and a key species in the Southern Ocean ecosystem. Krill builds up a huge biomass and its synchronized behavioral patterns, such as diel vertical migration (DVM), substantially impact ecosystem structure and carbon sequestration. However, the mechanistic basis of krill DVM is unknown and previous studies of krill behavior in the laboratory were challenged by complex behavior and large variability. Using a new experimental set-up, we recorded the swimming activity of individual wild-caught krill under light-dark cycles. Krill individuals exhibited differential phototactic responses to the light regime provided. However, using a new activity metric, we showed for the first time a consistent nocturnal increase in krill swimming activity in a controlled environment. Krill swimming activity in the new set-up was strongly synchronized with the light-dark cycle, similar to the diel vertical migration pattern of krill in the field when the krill were sampled for the experiment, demonstrated by hydroacoustic recordings. The new set-up presents a promising tool for investigating the mechanisms underlying krill behavioral patterns, which will increase our understanding of ecological interactions, the spatial distribution of populations, and their effects on biogeochemical cycles in the future.

Systematical Investigation on Anti-Fatigue Function and Underlying Mechanism of High Fischer Ratio Oligopeptides from Antarctic Krill on Exercise-Induced Fatigue in Mice.

High Fischer ratio oligopeptides (HFOs) have a variety of biological activities, but their mechanisms of action for anti-fatigue are less systematically studied at present. This study aimed to systematically evaluate the anti-fatigue efficacy of HFOs from Antarctic krill (HFOs-AK) and explore its mechanism of action through establishing the fatigue model of endurance swimming in mice. Therefore, according to the comparison with the endurance swimming model group, HFOs-AK were able to dose-dependently prolong the endurance swimming time, reduce the levels of the metabolites (lactic acid, blood urea nitrogen, and blood ammonia), increase the content of blood glucose, muscle glycogen, and liver glycogen, reduce lactate dehydrogenase and creatine kinase extravasation, and protect muscle tissue from damage in the endurance swimming mice. HFOs-AK were shown to enhance Na+-K+-ATPase and Ca2+-Mg2+-ATPase activities and increase ATP content in muscle tissue. Meanwhile, HFOs-AK also showed significantly antioxidant ability by increasing the activities of superoxide dismutase and glutathione peroxidase in the liver and decreasing the level of malondialdehyde. Further studies showed that HFOs-AK could regulate the body's energy metabolism and thus exert its anti-fatigue effects by activating the AMPK signaling pathway and up-regulating the expression of p-AMPK and PGC-α proteins. Therefore, HFOs-AK can be used as an auxiliary functional dietary molecules to exert its good anti-fatigue activity and be applied to anti-fatigue functional foods.

Anthropogenic particles determination in northern krill (Meganyctiphanes norvegica) from the Azores region: A keystone species for marine food webs.

Plastic pollution poses a significant threat to marine ecosystems. Microfibres from fabrics have become the most prevalent shape of microplastic found in the marine environment. The northern krill (Meganyctiphanes norvegica) is the most abundant euphausiid species in the northern hemisphere, playing a crucial role in various pelagic ecosystems. Anthropogenic microparticles in northern krill was assessed for the first time in samples collected in the Azores on two occasions - April 2019 (n = 480) and April 2023 (n = 480). Analysis of all individuals revealed 533 anthropogenic particles, with an average abundance of 0.56 ± 0.14 items per individual and, no significant differences between years. Microfibres were the most common shape (94.8 %), with the remaining items being fragments (5.2 %), and blue and black were the predominant colours. MicroFourier transform infrared spectroscopy analysis (µFTIR) of 22.1 % of the total number of particles, showed that they were mainly cellulosic (65.3 %) - either natural or semisynthetic - followed by polyester (7.6 %). Our finding of microplastics in the northern krill raises important questions due to its crucial role in marine food webs. The intake of anthropogenic particles, particularly those that are 100 % synthetic, suggests that the northern krill may act as a transfer vector of these pollutants to higher trophic levels.

Krill Oil Ameliorates Liver Injury in Diabetic Mice by Activating Antioxidant Capacity and Inhibiting Ferroptosis.

Diabetic liver injury (DLI) has raised attention in recent years. Liver injury results from type 2 diabetes mellitus (T2DM), and in turn accelerates T2DM development by exacerbating insulin resistance. However, effective approaches for mitigating DLI are surprisingly rare. Krill oil (KO) is an alternative source of omega-3 polyunsaturated fatty acids, possessing antioxidant and anti-inflammatory capacities. Here we investigated the effect of KO supplementation on DLI in a mouse model of T2DM induced by streptozotocin and high-fat diet. The diabetic mice developed glucose intolerance, elevated serum alanine aminotransferase and aspartate aminotransferase, and hepatic pathological injuries such as vacuolation, lipid accumulation and fibrosis deposition, the effects of which were mitigated by KO. Further investigation showed that KO ameliorated the DM-induced expression of fibrotic and inflammatory genes. Notably, KO dramatically reduced hepatic oxidative gene expression, lipid peroxidation and ROS production, all of which are hallmarks of ferroptosis. The inhibitory effect of KO on ferroptosis was confirmed by the KO-decreased hepatic expression of GPX4, COX2 and ACSL4, as well as the KO-reduced hepatic iron deposition. Further, KO restored hepatic NRF2 antioxidant signaling which combats ferroptosis. The present study may provide KO supplementation as a viable approach for the intervention of DLI.