Recent progress in Porphyra haitanensis polysaccharides: Extraction, purification, structural insights, and their impact on gastrointestinal health and oxidative stress management.

Porphyra haitanensis, a red seaweed species, represents a bountiful and sustainable marine resource. P. haitanensis polysaccharide (PHP), has garnered considerable attention for its numerous health benefits. However, the comprehensive utilization of PHP on an industrial scale has been limited by the lack of comprehensive information. In this review, we endeavor to discuss and summarize recent advancements in PHP extraction, purification, and characterization. We emphasize the multifaceted mechanisms through which PHP promotes gastrointestinal health. Furthermore, we present a summary of compelling evidence supporting PHP's protective role against oxidative stress. This includes its demonstrated potent antioxidant properties, its ability to neutralize free radicals, and its capacity to enhance the activity of antioxidant enzymes. The information presented here also lays the theoretical groundwork for future research into the structural and functional aspects of PHP, as well as its potential applications in functional foods.

Functional characterization of NOD1 from golden pompano Trachinotus ovatus.

Fish rely on innate immune system for immunity, and nucleotide-binding oligomerization domain-like receptors (NLRs) are a vital group of receptor for recognition. In the present study, NOD1 gene was cloned and characterized from golden pompano Trachinotus ovatus, a commercially important aquaculture fish species. The ORF of T. ovatus NOD1 was 2820 bp long, encoding 939 amino acid residues with a highly conserved domains containing CARD-NACHT-LRRs. Phylogenetic analysis revealed that the T. ovatus NOD1 clustered with those of fish and separated from those of birds and mammals. T. ovatus NOD1 has wide tissue distribution with the highest expression in gills. Bacterial challenges (Streptococcus agalactiae and Vibrio alginolyticus) significantly up-regulated the expression of NOD1 with different response time. The results of T. ovatus NOD1 ligand recognition and signaling pathway analysis revealed that T. ovatus NOD1 could recognize iE-DAP at the concentration of ≧ 100 ng/mL and able to activate NF-κB signaling pathway. This study confirmed that NOD1 play a crucial role in the innate immunity of T. ovatus. The findings of this study improve our understanding on the immune function of NOD1 in teleost, especially T. ovatus.

Impact of anthropogenic global hypoxia on the physiological response of bivalves.

Dissolved oxygen (DO) is an important parameter that affects the biology, physiology, and immunology of aquatic animals. In recent decades, DO levels in the global oceans have sharply decreased, partly due to an increase in atmospheric carbon dioxide, temperature, and anthropogenic nutrient loads. Although there have been many reports on the effects of hypoxia on the survival, growth, behavior, and immunity of bivalves, this information has not been well organized. Therefore, this article provides a comprehensive review of the effects of hypoxia on bivalves. In general, hypoxia negatively impacts the food consumption rate and assimilation efficiency, as well as increasing respiration rates in many bivalves. As a result, it reduces the energy allocation for bivalve growth, shell formation, and reproduction. In severe cases, prolonged exposure to hypoxia can result in mass mortality in bivalves. Moreover, hypoxia also has adverse effects on the immunity and response of bivalves to predators, including decreased burial depths, sensitivity to predators, impairment of byssus production, and negatively impacts on the integrity, strength, and composition of bivalve shells. The tolerance of bivalves to hypoxia largely depends on size and species, with larger bivalves being more susceptible to hypoxia and intertidal species being relatively more tolerant to hypoxia. The information in this article is very useful for elucidating the current research status of hypoxia on bivalves and determining future research directions.

Protein quality of commercially important edible bivalves.

Bivalves are a high-quality source of animal protein for human consumption. In recent years, the demand for bivalve proteins has increased dramatically, leading to a sharp increase in global production of marine bivalves. To date, although the amino acid profiles of many bivalves have been reported, such information has not been well organized. Therefore, there is an urgent need for a comprehensive scientific review of the protein quality of bivalves, especially commercially important edible bivalves. In this context, this study was conducted to evaluate the protein quality of commercially important edible bivalves. In general, most bivalves are rich in protein (> 50% of their dry weight) and amino acids (> 30 g/100g protein). Although most species of bivalves are rich in essential amino acids (EAA) (up to 50 g/100g protein), some species of edible bivalves have very low levels of EAA (< 5 g/100g protein). Based on the AA score, almost all bivalves have at least two limiting AAs. Most bivalve proteins provides delicious flavors with unami, sweetness and a hint of bitterness. The findings of this study not only serve as a a guide for selecting appropriate bivalves based on consumer preferences for specific AAs or AA scores, but also provide information on potential bivalve species for aquaculture to produce higher protein quality to meet the growing demand for high quality animal protein.

The impact of elevated temperature on the macro-nutrients of commercially important marine bivalves: the implication of ocean warming.

Bivalves are nutritious animal protein source for humans, rich in high quality proteins, lipids, and carbohydrates. Many studies have shown that ocean warming has detrimental effects on the nutritional quality of bivalves. Although a number of studies are available on the effect of ocean warming on the nutritional value of bivalves, this information is not well organized. In this context, the current study provides a critical review of the effects of ocean warming on the nutritional quality of commercially important edible marine bivalves. In general, ocean warming has caused a reduction in the total lipid and carbohydrate content of bivalves, especially those bivalves inhabiting temperate regions. As for protein, there is no general trend in the effects of ocean warming on the protein reserves of bivalves. In addition, the specific effects of elevated temperature on the macro-nutrients of bivalves highly depend on the tissues, sex and developmental stages of bivalves, as well as seasonal factors. This review not only fills in the knowledge gap regarding the effects of elevated temperature on the macro-nutrients of commercially important marine bivalves but also provides guidance for the establishment of bivalve aquaculture and fisheries management plans to mitigate the impact of climate change.

Effects of bivalve aquaculture on plankton and benthic community.

Global human population has increased dramatically over the past 50 years. As a result, marine fisheries and finfish aquaculture have become increasingly unsustainable, driving bivalve aquaculture to become an important food industry for the production of marine animal protein to support the growing market demand for animal protein. It is projected that the rate of bivalve aquaculture expansion will be greatly accelerated in the near future as the human population continues to increase. Although it is generally believed that unfed bivalve aquaculture has less impact on the environment than finfish aquaculture, the rapid expansion of bivalve aquaculture has raised concerns about its potential negative impact, especially on plankton and benthic community. Therefore, there is an urgent need to update the potential effects of bivalve aquaculture on plankton and benthic community. This article reviews the present state of knowledge on environmental issues related to bivalve aquaculture, and discusses potential mitigation measures for the environmental impacts induced by expansion of bivalve aquaculture. This review provides guidance for scientists and farm managers to clarify the current state of research and identify priority research needs for future bivalve aquaculture research. Therefore, specific management strategies can be formulated for the sustainable development and expansion of bivalve aquaculture.

Effects of food processing on the lipid nutritional quality of commercially important fish and shellfish.

Fish and shellfish are important sources of high quality lipids, especially omega-3 long-chain polyunsaturated fatty acids. In most countries, seafood is eaten cooked to eliminate any potential parasites and pathogens. In addition, cold storage plays an important role in extending the shelf life of seafood. However, both cooking and storage processes can cause alterations in the lipid content and fatty acid profile of fish and shellfish. Although the lipid nutritional quality of fish and shellfish have recently been reviewed, these reviews mainly focus on raw seafood, and information on the impact of food processing on the lipid nutritional quality of fish and shellfish still lacks coherence. Therefore, this study was carried out to provides a critical reviews on the effects of food processing, especially cooking and cold storge, on the lipid nutritional quality of fish and shellfish. Overall, from the perspective of lipid nutritional quality, baking and steaming are the most recommended cooking methods for fish and shellfish, respectively, while it is strongly not recommended to fry seafood with margarine. For cold storage, 3 days and 2 weeks are the most recommended storage periods for refrigeration and frozen storage, respectively. This article can provides consumers with useful information to choose food preparation and storage methods based on their personal interest in specific lipid nutritional quality indicators.

siRNA Silencing of FpVtg Induces Ovarian Cell Apoptosis in Redtail Prawn, Fenneropenaeus penicillatus.

Inadequate gonadal maturation and poor spawning performance increasingly threaten the sustainability of shrimp aquaculture. Unraveling the mechanisms regulating ovarian development and maturation hence is critical to address industry challenges. Vitellogenin (Vtg), a precursor of yolk protein found in the hepatopancreas and ovary of shrimp, plays a key role in facilitating shrimp's oocyte maturation and embryonic development after oviposition. This study found that FpVtg was specifically expressed in F. penicillatus hepatopancreas and ovary. FpVtg was localized predominantly in the oocyte cytoplasm and distributed uniformly in the hepatopancreas tissue. Silencing FpVtg led to apoptosis in both hepatopancreas and ovary tissues. Furthermore, FpVtg depletion upregulated the expression of ovarian peritrophin 1, ovarian peritrophin 2, serine proteinase inhibitor 6, and juvenile hormone esterase-like carboxylesterase 1, while downregulated that of vitellogenin, delta-9 desaturase, and insulin-like receptor. KEGG pathway analysis implicated such as PI3K-AKT signaling, RNA transport, ECM-receptor interaction, hippo signaling, oocyte meiosis, and apoptosis were enriched and involved in ovarian development. These findings have provided insights into the FpVtg's reproductive role and the associated regulatory genes and pathways in F. penicillatus. This knowledge can contribute to establishing strategies to improve the breeding and aquaculture production of F. penicillatus by elucidating its vitellogenesis regulation in redtail prawn and other penaeid species. Further characterization of the implicated pathways and genes will clarify the intricacies underlying ovarian maturation.

Effects of culinary treatments on the lipid nutritional quality of fish and shellfish.

Coronary heart disease (CHD) is one of the leading causes of death worldwide. Seafood, especially fish and shellfish, is a healthy food that reduces the risk of CHD. In many regions, seafood is consumed cooked to eliminate potentially pathogenic microorganisms. Although there have been many reports of culinary preparations causing changes in the fatty acid profile of fish and shellfish, this information has not been well organized, and most of it is not associated to CHD. Therefore, this study was conducted to study the effect of culinary treatments of seafood on lipid nutritional quality in relation to promotion/prevention of CHD. In this study, fatty acid profiles of fish and shellfish prepared with different culinary preparations were obtained from published literature. Lipid nutritional quality indices related to promoting/preventing CHD were calculated and analyzed to reveal the effects of culinary treatment on the lipid nutritional quality of fish and shellfish in promoting/preventing of CHD. The information in this article is very useful and can fill the knowledge gap of the effects of culinary preparation on the lipid nutritional quality of fish and shellfish. Such information is very useful for guiding consumers to choose better ways to cook fish and shellfish to reduce the risk of CHD.

Effects of high stocking density on growth performance and expression of MyD88, and its temporal expression under the challenge of Vibrio parahaemolyticus in the noble scallop Chlamys nobilis.

High stocking density has been regarded as an adverse factor in bivalve aquaculture. However, its subsequent molecular response to pathogenic bacteria has been little studied. In order to study the question, a novel MyD88 was first cloned using adult noble scallops Chlamys nobilis (CnMyD88), and its tissue distribution was investigated. Then, 1860 juvenile scallops were divided into two groups with two initial densities of high density (200 individuals/layer, HD) and normal density (110 individuals/layer, ND) and in-situ cultured for three months, in which their growth, survival, and the differential expression of CnMyD88 were examined, respectively. Finally, scallops were injected with the Vibrio parahaemolyticus to assess the temporal expression of CnMyD88. As the results show, CnMyD88 cDNA has a full length of 2241 bp and contains an 1107 bp ORF that encodes a 368-derived protein. It was widely expressed in examined tissues with a significantly higher level in hemolymph, intestine, mantle, and gonad than others. Besides, the HD group showed lower growth (0.39 ± 0.05 mm/day) and survival (37.00 ± 8.49%) than the ND group (0.55 ± 0.02 mm/day and 76.82 ± 5.78%). More importantly, the HD group exhibited significantly lower expression levels of CnMyD88 in their examined tissues than the ND group. After V. parahaemolyticus challenging, CnMyD88 had significantly lower expression levels in the scallops from the HD group than that of the scallops from the ND group at 6th, 24th, and 36th. The present results indicated that high stocking density not only made adverse impacts on growth and survival but also may induce immunosuppression in the noble scallop. Therefore, appropriate low stocking density may be worth considering to adopt in scallop aquaculture.

Silencing of novel TtVtg6-like induced ovarian cell apoptosis in ancient chelicerate Tachypleus tridentatus.

Vitellogenin (Vtg) serves as the precursor of yolk protein and exhibits widespread distribution in tissues, including in the ovary of both vertebrates and invertebrates. Vtg plays a critical role in facilitating oocyte maturation and embryonic development following oviposition. In this study, we have successfully elucidated the complete transcript sequence of TtVtg6-like from an ancient chelicerate Tachypleus tridentatus. The TtVtg6-like transcript encompassed a length of 4887 bp and encoded 1629 amino acids residues. Notably, TtVtg6-like was found to contain 25 exons. Furthermore, the molecular weight and isoelectric point of TtVtg6-like were determined to be 191.6 KDa and 6.73, respectively. Subsequent mRNA expression analysis demonstrated the specific expression of TtVtg6-like in ovary and yellow connective tissue. In addition, TtVtg6-like was located and distributed in both ovary and yellow connective tissue. Intriguingly, employing an siRNA approach to silence TtVtg6-like resulted in a decrease in TtVtg6-like transcription levels. Concomitantly, TtVtg6-like silencing led to increase production of ROS, ultimately resulting in DNA damage and cell apoptosis within the ovarian primary cell. The induction of apoptosis ovarian primary cells due to TtVtg6-like silencing was further corroborated through TUNEL assay and flow cytometry analysis. Overall, our findings underscore the significance of TtVtg6-like in ovarian cell development, revealing its potential association with ovarian cell apoptosis. Consequently, the insights gained from this study contribute to the future exploration of vitellogenesis and ovarian development in T. tridentatus.

The impact of climate change on Omega-3 long-chain polyunsaturated fatty acids in bivalves.

Omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA) have many health benefits to human. Increasing evidence have shown that climate change reduces the availability of plankton n-3 LC-PUFA to primary consumers which potentially reduces the availability of n-3 LC-PUFA to human. Since marine bivalves are an important source of n-3 LC-PUFA for human beings, and bivalve aquaculture completely depends on phytoplankton in ambient water as food, it is important to understand the impact of climate change on the lipid nutritional quality of bivalves. In this study, fatty acid profile of different bivalves (mussels, oysters, clams, scallops and cockles) from different regions (tropical, subtropical and temperate) and time (before 1990, 1991-1995, 1996-2000, 2001-2005, 2006-2010, 2011-2015, 2016-2020) were extracted from published literature to calculate various lipid nutritional quality indicators. The results of this study revealed that the effects of global warming and declines in aragonite saturation state on the lipid content and lipid indices of bivalves are highly dependent on the geographical region and bivalves. In general, global warming has the largest negative impact on the lipid content and indices of temperate bivalves, including decreasing the PUFA/SFA, EPA + DHA and n-3/n-6. However, global warming has a much smaller negative impact on lipid content and lipid indices in other regions. The declines of aragonite saturation state in seawater promotes the accumulation of lipid content in tropical and subtropical bivalves, but it compromised the PUFA/SFA, EPA + DHA and n-3/n-6 of bivalves in all regions. The findings of this study not only fill the knowledge gap of the impact of climate change on the lipid nutritional quality of bivalves, but also provide guidance for the establishment of bivalve aquaculture and fisheries management plans to mitigate the impact of climate change.

Bioactivity of polysaccharides derived from bivalves.

Bivalves have high diversity, widely distributed in various aquatic environments, including saltwater, brackish water and freshwater. Bivalves are known to rich in polysaccharides and have wide applications in functional foods, pharmaceuticals, and industrial research. Despite many relevant reports are available, the information is poorly organized. Therefore, in this study, we conducted a comprehensive scientific review on the potential bioactivity of polysaccharides derived from bivalves. In general, the polysaccharides derived from bivalves possess various bioactive properties, including anticancer, antioxidant, anticoagulant and immunomodulatory activities. The bioactivity of these biomolecules highly depends on the bivalve species, extraction methods, purification methods, dosages, etc. The information in this study can provide an overview of the bioactivities of bivalve polysaccharides. This is very useful to be used as a guide for identifying the health benefits of polysaccharides derived from different bivalve species.

Post-COVID-19 syndrome management: Utilizing the potential of dietary polysaccharides.

The COVID-19 pandemic has caused significant global impact, resulting in long-term health effects for many individuals. As more patients recover, there is a growing need to identify effective management strategies for ongoing health concerns, such as post-COVID-19 syndrome, characterized by persistent symptoms or complications beyond several weeks or months from the onset of symptoms. In this review, we explore the potential of dietary polysaccharides as a promising approach to managing post-COVID-19 syndrome. We summarize the immunomodulatory, antioxidant, antiviral, and prebiotic activities of dietary polysaccharides for the management of post-COVID-19 syndrome. Furthermore, the review investigates the role of polysaccharides in enhancing immune response, regulating immune function, improving oxidative stress, inhibiting virus binding to ACE2, balancing gut microbiota, and increasing functional metabolites. These properties of dietary polysaccharides may help alleviate COVID-19 symptoms, providing a promising avenue for effective treatment strategies.

Marine algal polysaccharides as future potential constituents against non-alcoholic steatohepatitis.

Non-alcoholic steatohepatitis (NASH) is one of the most chronic and incurable liver diseases triggered mainly by an inappropriate diet and hereditary factors which burden liver metabolic stress, and may result in liver fibrosis or even cancer. While the available drugs show adverse side effects. The non-toxic bioactive molecules derived from natural resources, particularly marine algal polysaccharides (MAPs), present significant potential for treating NASH. In this review, we summarized the protective effects of MAPs on NASH from multiple perspectives, including reducing oxidative stress, regulating lipid metabolism, enhancing immune function, preventing fibrosis, and providing cell protection. Furthermore, the mechanisms of MAPs in treating NASH were comprehensively described. Additionally, we highlight the influences of the special structures of MAPs on their bioactive differences. Through this comprehensive review, we aim to further elucidate the molecular mechanisms of MAPs in NASH and inspire insights for deeper research on the functional food and clinical applications of MAPs.

Role of Polysaccharides from Marine Seaweed as Feed Additives for Methane Mitigation in Ruminants: A Critical Review.

Given the increasing concerns regarding greenhouse gas emissions associated with livestock production, the need to discover effective strategies to mitigate methane production in ruminants is clear. Marine algal polysaccharides have emerged as a promising research avenue because of their abundance and sustainability. Polysaccharides, such as alginate, laminaran, and fucoidan, which are extracted from marine seaweeds, have demonstrated the potential to reduce methane emissions by influencing the microbial populations in the rumen. This comprehensive review extensively examines the available literature and considers the effectiveness, challenges, and prospects of using marine seaweed polysaccharides as feed additives. The findings emphasise that marine algal polysaccharides can modulate rumen fermentation, promote the growth of beneficial microorganisms, and inhibit methanogenic archaea, ultimately leading to decreases in methane emissions. However, we must understand the long-term effects and address the obstacles to practical implementation. Further research is warranted to optimise dosage levels, evaluate potential effects on animal health, and assess economic feasibility. This critical review provides insights for researchers, policymakers, and industry stakeholders dedicated to advancing sustainable livestock production and methane mitigation.

A review of natural and anthropogenic radionuclide pollution in marine bivalves.

Radionuclide contamination in food is a public health issue. Bivalves are known to accumulate relatively high levels of radionuclides. Despite many relevant reports, this information is poorly organized. Therefore, in this study, we conducted a comprehensive scientific review of radionuclides in marine bivalves. In general, the accumulation of radionuclides in bivalves is highly species and tissue-specific, which may be due to the different biological half-life of radionuclides in different species and tissues. The trophic pathway is the main pathway for the accumulation of most radionuclides in bivalves, with polonium-210 (210Po) and lead-210 (210Pb) potentially selectively accumulating in the digestive glands, while 134Cs and 137Cs selectively accumulating in the adductor muscle and mantle. Some other radionuclides (radium-226 (226Ra) and strontium-90 (90Sr)) are absorbed along with other minerals (e.g. Calcium) and selectively accumulate in bivalve shells. The information in this study can provide an overview of radionuclide contamination in marine bivalves.

Oligosaccharides as Potential Regulators of Gut Microbiota and Intestinal Health in Post-COVID-19 Management.

The COVID-19 pandemic has had a profound impact worldwide, resulting in long-term health effects for many individuals. Recently, as more and more people recover from COVID-19, there is an increasing need to identify effective management strategies for post-COVID-19 syndrome, which may include diarrhea, fatigue, and chronic inflammation. Oligosaccharides derived from natural resources have been shown to have prebiotic effects, and emerging evidence suggests that they may also have immunomodulatory and anti-inflammatory effects, which could be particularly relevant in mitigating the long-term effects of COVID-19. In this review, we explore the potential of oligosaccharides as regulators of gut microbiota and intestinal health in post-COVID-19 management. We discuss the complex interactions between the gut microbiota, their functional metabolites, such as short-chain fatty acids, and the immune system, highlighting the potential of oligosaccharides to improve gut health and manage post-COVID-19 syndrome. Furthermore, we review evidence of gut microbiota with angiotensin-converting enzyme 2 expression for alleviating post-COVID-19 syndrome. Therefore, oligosaccharides offer a safe, natural, and effective approach to potentially improving gut microbiota, intestinal health, and overall health outcomes in post-COVID-19 management.

Porphyran from Porphyra haitanensis Enhances Intestinal Barrier Function and Regulates Gut Microbiota Composition.

In this study, the effects of a homogenous porphyran from Porphyra haitanensis (PHP) on the intestinal barrier and gut microbiota were investigated. The results showed that oral administration of PHP resulted in a higher luminal moisture content and a lower pH environment for the growth of beneficial bacteria in the colon of mice. PHP significantly increased the production of total short-chain fatty acids during the fermentation process. PHP made the intestinal epithelial cells of mice arrange more tidily and tightly with a significant increase in mucosal thickness. PHP also increased the amount of mucin-producing goblet cells and the expression of mucin in the colon, which maintained the structure and function of the intestinal mucosal barrier. Moreover, PHP up-regulated the expression of tight junctions including ZO-1 and occludin, improving the intestinal physical barrier function. The results of 16S rRNA sequencing showed that PHP regulated the composition of gut microbiota in mice, increasing the richness and diversity of gut microbiota and the ratio of Firmicutes to Bacteroidetes. This study revealed that the intake of PHP is beneficial for the gastrointestinal tract and PHP could be a potential source of prebiotics in the functional food and pharmaceutical industries.

Carotenoid content and composition: A special focus on commercially important fish and shellfish.

Carotenoids are natural pigments that provide many health benefits to living organisms. Although terrestrial plants are the major dietary source of carotenoids for humans, aquatic animals (especially fish and shellfish) are equally important because they are rich in certain important carotenoids lacking in fruits and vegetables. Although extensive research has focused on exploring the carotenoid content and composition in fish and shellfish, this information is poorly organized. This paper reviews the scientific evidence for the carotenoid content and composition in fish and shellfish. It makes serious attempts to summarize the relevant data published on specific research questions in order to improve the understanding of various evidence to clarify the research status of carotenoids in fish and shellfish and defining topics for future studies. From the analysis of published data, it is obvious that most fish and shellfish are rich in complex carotenoids (e.g. astaxanthin, fucoxanthin, fucoxanthinol, lutein). These carotenoids have stronger antioxidant effect, higher efficiency in removing the singlet oxygen and the peroxyl radicals, and have a variety of health benefits. Carotenoid levels in fish and shellfish depend on genotype, climatic conditions of the production area, storage and cooking methods. However, the information of the bioavailability of fish/shellfish carotenoids to human is very limited, which hinders the actual contributions to health. The findings of this study can be used as a guide to select appropriate fish and shellfish as dietary sources of carotenoids, and provide information about potential fish and shellfish species for aquaculture to produce carotenoids to meet part of the growing demand for natural carotenoids.