Dietary chromium modulates glucose homeostasis and induces oxidative stress in Pacific white shrimp (Litopenaeus vannamei)

Transcriptome, histology, and enzyme activities analysis of liver in Phoxinus lagowskii to the low temperature stress and recovery

Assessing the response and resilience of fish to low temperatures over different time scales can provide valuable insights into their mechanisms of adaptation to cold conditions. Farmed Amur minnows (Phoxinus lagowskii) frequently encounter low temperatures, especially during winter. However, the specific responses of P. lagowskii to low-temperature stress remain largely unexplored. In this study, we examined serum glucose and cortisol levels, histological changes, enzymes associated with phosphate and carbohydrate metabolism, triglyceride levels, and liver transcriptomics under various conditions: control (CK), short-term cold exposure (6 days, SC), prolonged cold exposure (14 days, PC), and recovery (RY) from cold exposure at 2 °C. Liver vacuolation was observed during short-term cold exposure. Additionally, we analyzed the enzymatic activity related to carbohydrate and lipid metabolism in serum and liver. Liver transcriptomic data revealed that the PPAR signaling pathway and autophagy-related genes were enriched during short-term cold exposure. Carbohydrate metabolism-related pathways, including the AMPK and MAPK signaling pathways, were significantly enriched after prolonged cold exposure. Metabolic pathways such as fat digestion and absorption, glycine, serine, and threonine metabolism, and arginine and proline metabolism were significantly enriched in the recovery group. Rapid warming after prolonged cold stress allowed P. lagowskii to recover quickly. These findings suggest that P. lagowskii has a strong adaptive capacity for energy metabolism during prolonged cold exposure and the ability to recover rapidly from cold stress. A comprehensive examination of the histological, physiological, biochemical, and molecular responses of P. lagowskii to low temperatures is crucial for developing effective strategies for cultivating this species in challenging environments.

Toxicity of three microcystin variants on the histology, physiological and metabolism of hepatopancreas and intestinal microbiota of Litopenaeus vannamei

Microcystins (MCs) are prevalent harmful contaminants within shrimp aquaculture systems, exhibiting a diverse array of variants. Gut microbiota can engage in mutual interactions with the host through the gut-liver axis. In this study, the shrimp Litopenaeus vannamei were subjected to three different variants of MCs (LR, YR, RR) at a concentration of 1 μg/L each, and elucidated the alterations in both intestinal microbiota and hepatopancreas physiological homeostasis. The results showed that all three variants of MCs prompted histological alterations in the hepatopancreas, induced elevated levels of oxidative stress biomarkers (H2O2, T-SOD, and CAT), disturbed the transcription levels of immune-related genes (Crus, ALF, and Lys), along with an increase in apoptotic genes (Casp-3 and P53). Furthermore, the metabolic profiles of the hepatopancreas were perturbed, particularly in amino acid metabolism such as "lysine degradation" and "β-alanine metabolism"; the mTOR and FoxO signaling were also influenced, encompassing alterations in the transcription levels of related genes. Additionally, the alterations were observed in the intestinal microbiota's diversity and composition, particularly potential beneficial bacteria (Alloprevotella, Bacteroides, Collinsella, Faecalibacterium, and Prevotellaceae UCG-001), which exhibited a positive correlation with the metabolite berberine. These findings reveal that the three MCs variants can impact the health of the shrimp by interfering with the homeostasis of intestinal microbial and hepatopancreas physiology.

Assessing Metal Toxicity on Crustaceans in Aquatic Ecosystems: A Comprehensive Review

Residual concentrations of some trace elements and lightweight metals, including cadmium, copper, lead, mercury, silver, zinc, nickel, chromium, arsenic, gallium, indium, gold, cobalt, polonium, and thallium, are widely detected in aquatic ecosystems globally. Although their origin may be natural, human activities significantly elevate their environmental concentrations. Metals, renowned pollutants, threaten various organisms, particularly crustaceans. Due to their feeding habits and habitat, crustaceans are highly exposed to contaminants and are considered a crucial link in xenobiotic transfer through the food chain. Moreover, crustaceans absorb metals via their gills, crucial pathways for metal uptake in water. This review summarises the adverse effects of well-studied metals (Cd, Cu, Pb, Hg, Zn, Ni, Cr, As, Co) and synthesizes knowledge on the toxicity of less-studied metals (Ag, Ga, In, Au, Pl, Tl), their presence in waters, and impact on crustaceans. Bibliometric analysis underscores the significance of this topic. In general, the toxic effects of the examined metals can decrease survival rates by inducing oxidative stress, disrupting biochemical balance, causing histological damage, interfering with endocrine gland function, and inducing cytotoxicity. Metal exposure can also result in genotoxicity, reduced reproduction, and mortality. Despite current toxicity knowledge, there remains a research gap in this field, particularly concerning the toxicity of rare earth metals, presenting a potential future challenge.

Essential and non-essential elements in tuna and billfish around the world: Distribution patterns and influencing factors

Tuna and billfish are widely distributed in oceans worldwide. Their survival is relied on a decent share of essential and non-essential elements. We conducted a comprehensive evaluation of essential and non-essential elements in livers of tuna and billfish collected from global oceans. The individual element consistently shown similar orders of magnitude in both tuna and billfish, with essential elements generally being 1-3 orders of magnitude higher than non-essential elements. Various physicochemical properties and behaviors contributed to four distinct clusters of these elements. Also, element distribution pattern indicated the presence of four sample groups based on regions and categories. Nine elements served as characteristic indicators. Among them, fish category was the most important influencing factor. Hg, Fe, Tl, Co, and Se were influenced by body size, trophic level, and feeding habits. Ni was influenced by sampling regions, while Mg, Mn and As were influenced by body size and local primary production.

Assessing pathways of heavy metal accumulation in aquaculture shrimp and their introductions into the pond environment based on a dynamic model and mass balance principle

The impact of heavy metals (HMs) on the quality of aquaculture products has attracted worldwide attention. Since Litopenaeus vannamei is a popular aquaculture product among consumers worldwide, it is of great importance to guarantee its dietary safety. An in-situ monitoring program lasting for three months in a typical Litopenaeus vannamei farm found that Pb (100 %) and Cr (86 %) in the adult shrimp were higher than the safety guidelines. In the meantime, Cu (100 %), Cd (100 %) in the water and Cr (40 %) in the feed exceeded the corresponding thresholds. Therefore, quantification of different exposure pathways of shrimp and contamination origins in pond is valuable to improve the dietary safety of the shrimp. Based on Optimal Modeling for Ecotoxicological Applications (OMEGA), Cu was primarily from the ingestion of feed, accounting for 67 % of bioaccumulation, while Cd, Pb and Cr primarily entered shrimp through the adsorption from overlying water (53 % for Cd and 78 % for Pb) and porewater (66 % for Cr), respectively. The HMs in the pond water were further tracked based on a mass balance analysis. The main source of Cu in the aquaculture environment was feed, being responsible for 37 % of the total input. Pb, Cd and Cr were primarily from the inlet water with contributions of 84 %, 54 % and 52 %, respectively. In summary, the proportions of different exposure pathways and origins of HMs in pond-cultured shrimp and its living environment varied widely. To keep end-consumers eating healthily, species specific treatment is required. Feed should be regulated more for Cu. Aimed pretreatments for Pb and Cd in influent water are needed and an additional immobilization for Cr in sediment porewater should be investigated. After implementation of these treatments, the food quality improvement could be further quantified based on our prediction model.

First transcriptome profiling in gill and hepatopancrease tissues of Metapenaeus ensis in response to acute ammonia-N stress

The greasyback shrimp, Metapenaeus ensis, suffers from ammonia-N stress during intensive factory aquaculture. Optimizing ammonia-N stress tolerance has become an important issue in M. ensis breeding. The metabolic and adaptive mechanisms of ammonia-N toxicity in M. ensis have not been comprehensively understood yet. In this study, a large number of potential simple sequence repeats (SSRs) in the transcriptome of M. ensis were identified. Differentially expressed genes (DEGs) in the gill and hepatopancreas at 24 h post-challenges under high concentrations of ammonia-N treatment were detected. We obtained 20,108,851-27,681,918 clean reads from the control and high groups, assembled and clustered a total of 103,174 unigenes with an average of 876 bp and an N50 of 1189 bp. Comparative transcriptome analyses identified 2000 different expressed genes in the gill and 2010 different expressed genes in the hepatopancreas, a large number of which were related to immune function, oxidative stress, metabolic regulation, and apoptosis. The results suggest that M. ensis may counteract ammonia-N toxicity at the transcriptome level by increasing the expression of genes related to immune stress and detoxification metabolism, and that selected genes may serve as molecular indicators of ammonia-N. By exploring the genetic basis of M. ensis' ammonia-N stress adaptation, we constructed the genetic networks for ammonia-N adaptation. These findings will accelerate the understanding of M. ensis' ammonia-N adaptation, contribute to the research of future breeding, and promote the level of factory aquaculture of M. ensis.

Dietary Supplementation with Chromium DL-Methionine Enhances Growth Performance of African Catfish (Clarias gariepinus)

Sustainable aqua feeds have become an urgent necessity for future-oriented aquaculture sector development, and especially mineral supply could be limited when diets are being prepared with low amounts of animal-based sources. Since knowledge about the efficiency of organic trace mineral supplementation in different species of fish is limited, the effects of chromium DL-methionine in African catfish nutrition were evaluated. Four commercially based diets with increasing chromium DL-methionine supplementation (0, 0.2, 0.4, and 0.6 mg Cr kg-1) in the form of Availa-Cr 1000 were fed to African catfish (Clarias gariepinus B., 1822) in quadruplicate groups for 84 days. Growth performance parameters (final body weight, feed conversion ratio, specific growth rate, daily feed intake, protein efficiency ratio, and protein retention efficiency), biometric indices (mortality, hepatosomatic index, spleen somatic index, and hematocrit), and mineral retention efficiency were assessed at the end of the feeding trial. The specific growth rate was significantly increased in fish-fed diets with 0.2 mg Cr kg-1 and 0.4 mg Cr kg-1 supplementation in comparison with control and based on the second-degree polynomial regression analysis; supplementation with 0.33 mg Cr kg-1 was optimal in commercially based diets for African catfish. Chromium retention efficiency was reduced with increasing supplementation levels; however, the chromium content of the whole body was comparable to literature. The results suggest that organic chromium supplementation is a viable and safe supplement for diets to increase the growth performance of African catfish.

Marine shrimps as biomonitors of the Fundão (Brazil) mine dam disaster: A multi-biomarker approach

The disruption of the Fundão dam released 43 million m³ of mine tailings into the Doce River until it flowed into the ocean through the estuary. The mine tailing changed the composition of metals in water and sediment, creating a challenging scenario for the local biota. We used multivariate analyzes and the integrated biomarker response index (IBR) to assess the impact of mine tailings on the bioaccumulation profile (As, Cd, Cr, Cu, Fe, Mn, Pb and Zn) as well as the biomarkers response in gills, hepatopancreas and muscle of shrimps sampled from different sectors during two dry seasons (dry1 and dry2) (Sep/Oct 2018; 2019) and two wet seasons (wet1 and wet2) (Jan/feb 2019; 2020). There was seasonal and local effect under bioaccumulation and biomarker response revealing that the pattern responses seen in each sector sampled changed according to the season. The greater IBR added to the strong association among the most metals tissue content (Cd, Cr, Cu and Mn) and sectors sampled during dry 1 suggests greater bioavailability of these metals to the environment in this period. Estuarine sectors stand out for high Fe bioavailability, especially during wet1, which seems to be associated with greater metallothionein content in hepatopancreas of shrimps. Native species of marine shrimps proved to be successful indicators of sediment quality besides being sensitive to water contamination by metals. The multi-biomarkers approach added to multivariate analysis supports the temporal and seasonal effects, signalizing the importance of continuous monitoring of the estuarine region to better know about the bioavailability of these metals, mainly Fe, and their long-term effects on the local biota.