Aquaculture and Fisheries最新文献

Reliable, nondestructive fish freshness evaluation applicable during fish commercialization has been continuously pursued by scientists and industry. Taking into account that fish texture is primarily affected even at early stages of post-mortem storage, a relevant nondestructive testing framework for rapid textural assessment of fish freshness was developed in the past. Herein, an algorithm operating within the aforementioned framework and optimized for use in industrial environments is proposed. Sea bass (Dicentrarchus labrax) both freshly killed and stored on ice for 6 days have been used for comparative testing. The fish is part of a system, which is vibration-tested via a new testing protocol designed for easy implementation and robustness to noise. At the same time, a new closed-form analytical expression for the system response to the specific testing is computed and used along with experimental data, for obtaining specific mechanical (thus muscle-structural) characteristics of fish flesh. This computation is designed to only require readily available routines found in most relevant software. The algorithmic operational framework has been used in two different test setups (a custom-built test rig and a prototype device), with results following remarkably similar trends, clearly discriminating different textural (thus freshness) characteristics, and consequently validating the proposed approach.

The average values of the seasonal flesh biochemical composition (%) of the pearl oyster Pinctada imbricata radiata originated form 2 sampling sites, the gulfs of Evoikos (E) and Saronikos (S) in the Western Aegean Sea, showed that is rich in proteins (64.00 ± 1.86 -(E), 64.67 ± 2.95-(S)) with low fat content (10.96 ± 1.04-(E), 11.86 ± 1.13-(S)) and carbohydrates (13.29 ± 2.48- (E), 9.94 ± 4.32 (S)). The condition index ranged from 26.16% ± 5.04 in the autumn in (E), to 44.73% ± 7.50 in the summer in (S). The meat yield varied from 20.49% ± 3.20% in the summer in (E) to 30.73% ± 3.47% in the summer in (S). Both results demonstrate the high nutritional profile of the pearl oyster, supporting its suitability as a potential new Mediterranean seafood source for human consumption.

An essential aspect of product quality of aquatic foods is the rapid and accurate identification of bacterial species. From this perspective omics technologies prove to be very useful in the assessment of the quality and safety of seafood products. Such technologies can identify and detect low levels of contamination by pathogenic and spoilage bacteria and can be used to study the effects caused by processing and storage of seafood products. The integration of food processing with the monitoring of the microbial characteristics using conventional microbiological assays, coupled to molecular techniques may establish the baseline for the development of quicker and more sensitive and reliable methods for seafood safety screening. The use of combined omics technologies, including metagenomics, proteomics and metabolomics, coupled to conventional quality indices such as colour, texture and flavour offer a new tool for novel processing optimization to ensure seafood quality. The aim of this brief review is to outline how omics technologies can generate novel tools for integration into seafood processing and quality control. Considering that the main aspect of the review is the improvement of safety and quality of the final product, from production to consumption, emphasis is given to microbial identification and metabolite detection, the evaluation of the allergenic capacity of fish and seafood and optimization of postharvest processing. Deployment of omics for identification of potential microalgal products of relevance to seafood quality and safety is also considered.

Occurrence of biogenic amines in fresh fish and fishery products constitute a significant safety concern. Ingestion of histamine is identified as the causative agent of several food poisoning incidences on an annual basis. In addition, cadaverine, putrescine and tyramine have been recognized as potentiators of histamine poisoning. Accumulation of biogenic amines in fresh fish and fishery products has been mainly attributed to growth of bacteria possessing amino acid decarboxylase activity, which is facilitated by lack of hygienic conditions and strict temperature control during their storage. To this end, the effectiveness of traditional and modern approaches to control biogenic amine accumulation has been in the epicenter of intensive study. The aim of the present review article is to update and integrate current knowledge regarding the biogenic amine content of fresh fish and fishery products as well as the capacity of traditional and emerging control strategies.

Wastewater treatment plants release complex mixtures of chemicals into the aquatic environment as wastewater effluent (WWE); however, the effects of these mixtures are still poorly understood. Chinook salmon (Oncorhynchus tshawytscha) are a culturally important species in the Pacific Northwest and are a vital food resource for southern resident killer whales (Orcinus orca) that are listed as ‘critically endangered’ under the U.S. Endangered Species Act (ESA). Chinook populations have declined drastically in this region and have failed to show significant recovery despite regional-to-federal efforts, resulting in many populations being listed as threatened under the ESA. One source of stress to juvenile Chinook is chemical pollution from WWE during their outmigration along river corridors and residency in estuaries. In this study, we investigated effects of WWE on juvenile Chinook health in a ten-day exposure to dilutions of WWE from 0.1% to 20%. At the end of the exposure, we measured endpoints associated with endocrine disruption, brain function, osmoregulation, stress, and metabolism. Exposure to WWE significantly (α = 0.1 for all analyses) induced vitellogenesis, indicating endocrine system disruption. We saw significant reductions in plasma glucose, an indication of stress, and brain Na⁺/K⁺-ATPase (NKA) activity, an enzyme essential for neuronal signaling. Lastly, metabolism was affected as evidenced by altered total protein, cholesterol, and albumin in plasma, a drastic decrease in whole body lipid content, and a significant increase in visible liver anomalies. We compared contaminant concentrations in exposure water with effects concentrations from the literature for chemicals known to induce vitellogenin or inhibit brain NKA. For most contaminants, concentrations in exposure waters were several orders of magnitude below effects concentrations in the literature. The exception was estrogenic hormones, which were detected at similar concentrations in this study compared to concentrations in other studies that induced vitellogenin. Based on comparisons to the literature, contaminants measured in this study could not explain the inhibition of brain NKA; however, WWE mixtures contain many quantified and undetected compounds that are likely acting together to cause harmful effects in Chinook. This research highlights the need for improved wastewater treatment to improve aquatic health and mitigate effects to threatened species like Puget Sound Chinook salmon.

Endocrine-disrupting chemicals (EDCs) may mimic the endogenous neuroendocrine and endocrine messengers and interfere with developmental, reproductive, immune, metabolic and other physiological functions. Modulation of basal metabolic rate, energy metabolism, food intake and engorgement by endocrine disruptors may lead to loss of metabolic equilibrium. EDC-induced loss of metabolic homeostasis and obesity gave rise to the concept of metabolic-disrupting chemicals (MDC) and environmental obesogens. Elevated oxidative stress, alterations in the circadian clock, and energy-sensing homeostasis are some of the major pathophysiological conditions implicated in promoting metabolic disruption. Reportedly, fish are the most vulnerable candidate due to their direct exposure to metabolic disruptors in aquatic habitats. Though limited, studies conducted using piscine models have helped to identify MDCs in the aquatic environment. Notably, the molecular mechanisms through which MDCs can negatively influence the metabolism of hormones, epigenetic alteration, gut dysbiosis, and changes in endocrine and metabolic receptor expression and functions have recently gained considerable attention. In this review, we provide an update on the impact of MDCs on the initiators, cellular mediators, and hormone receptors related to the maintenance of metabolic homeostasis, with particular emphasis on fish models.

Hypoxia, a common environmental condition, can affect cell survival and physiological function by triggering oxidative stress. Akt/FoxO pathway has been proven to play a non-negligible role in the regulation of autophagy. However, the role of Akt/FoxO pathway in hypoxia-induced autophagy is unclear in fish. Therefore, in this study, grass carp hepatocyte cells (L8824) were treated by CoCl₂ to simulate hypoxia, and the results showed that CoCl₂ can increase the expression of Hif-1α protein at different concentrations or different treatment time. Further study found that hypoxia increased intracellular reactive oxygen species (ROS) level, and the expression of autophagy-related genes (LC3-II, pink1, beclin-1 and p62) and foxO1a/1b. The mitochondrial membrane potential (Δψm) was also depolarized, and autophagosomes were intriguingly detected by transmission electron microscope (TEM) after the treatment of hypoxia. Moreover, hypoxia inhibited Akt phosphorylation, while PI3K/Akt pathway inhibitor, LY294002 significantly up-regulated the expression of foxO1a/1b and autophagy-related genes. Additionally, silencing foxo1b also resulted in down-regulation of autophagy-related genes. It was demonstrated that hypoxia induced autophagy via Akt/FoxO1 pathway. These results will provide a new light on further understanding the role of Akt/FoxO pathway in the response to hypoxia in fish.