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This study assessed the feeding habits of four-finger threadfin fish, Eleutheronema tetradactylum, and its diet relationship with other fish species in the tropics. Fish samples were collected from four locations along the coastal regions of Thailand. A whole year field sampling event was conducted to investigate the diet relationship of threadfin fish with other ten co-existing fish species in Pattani Bay during January 2021 and January 2022. E. tetradactylum was an active and specific predator with significant diet shift during ontogeny. Specifically, the juvenile fish fed largely on zooplankton especially Acetes/shrimp postlarvae, and small sized-fish fed on penaeid shrimps, while medium and large-sized fish shifted their diets to a combination of penaeid shrimp, fish and squid. Size and sex of fish as well as site of collection significantly affected gut fullness index and average number of food type (p < 0.05). Transitional sex fish predated almost entirely on other fishes (87.2%), whereas male and female fish fed mainly on penaeid shrimp (66.5%) and other fish (51.3%), respectively. Fish size and mouth opening controlled the size of prey, with the larger fish with larger mouth-opening fed primarily on the larger size of prey. Moreover, E. tetradactylum shared its diets inclusively with Epinephelus coioides, Johnius belangerii, Scomberomorus commerson, Scomberoides lysan, Otolithes ruber and Lutjanus russelli. Penaeid shrimp and teleost fish were the main food types shared by these fishes. This study provided important information on the feeding habits of E. tetradactylum and its diet relationship with other co-existing fish species living in the same habitat of a tropical coastal region.

The electron-deficient N-heteroaromatic polymers are crucial for the high-tech applications of organic materials, especially in the electronic and optoelectronic fields. Thus, the development of new polymerizations to afford adaptable electron donating-accepting scaffolds in N-heteroaromatic polymers is in high demand. Herein, metal-free multicomponent polymerizations of diynes, diamines and glyoxylates are successfully developed for in-situ generation of poly(quinoline)s with high molecular weights (Mw up to 16 900) in nearly quantitative yields. By tuning the electron distributions of the polymer backbones, the resulting poly(quinoline)s show various aggregation-induced behaviors and photo-responsive abilities. The thin films of poly(quinoline)s can be readily fabricated into well-resolved photopatterns by photolithography techniques. They can be utilized as fluorescent probes to directly visualize the morphologies of polymer materials including spherulites and microphase separation of polymer blends. Their nanoparticles demonstrate sensitive and highly selective fluorescence quenching to hexavalent chromium ion Cr(VI), which provides access for the biological imaging of Cr(VI) in unicellular algae.

The root of Scutellaria baicalensis (Scutellaria Radix) has been used as herbal medicine for years in China; however, its stem and leaf (aerial part) are considered as waste. The water extract of aerial part of S. baicalensis, named as SBA, having anti-microbial property has been applied in fish aquaculture. To extend the usage of SBA in fish feeding, SBA was employed to feed pearl gentian grouper (a hybrid of Epinephelus fuscoguttatus♀ × Epinephelus lanceolatus♂), and subsequently the total fish output, the levels of digestive enzymes and inflammatory cytokines were determined. Feeding the fish with different doses of SBA for two months, the body length and weight were significantly increased by 5%–10%. In parallel, the expressions of alkaline phosphatase and growth-related factors in bone, liver and muscle of SBA-fed fish were doubled, which could account the growth promoting effect of SBA. Besides, the activity of digestive enzyme, lipase, and the expressions of anti-inflammatory cytokines were markedly stimulated by 2–3 times under the feeding of 3% SBA-containing diet. The results indicated the growth promoting activity of SBA in culture of pearl gentian grouper, as well as the effect of SBA in strengthening the immunity. These beneficial effects of SBA feeding can increase the total yield of pearl gentian grouper in aquaculture. Thus, the re-cycle of waste products during the farming of S. baicalensis herb in serving as fish feeding should be encouraged. © 2022

The root of Scutellaria baicalensis (Scutellaria Radix) has been used as herbal medicine for years, while its stem and leaf (aerial part) are considered as waste. The water extract from the aerial part of S. baicalensis (named as SBA) being included in the feeding of Siganus fuscescens (grey rabbit fish) has been shown to replace antibiotics in aquaculture with excellent outcome. To strengthen the usage of SBA in fish feeding, the total fish output and its nutritive value were determined here. Feeding the fishes with different doses of SBA for a month, the body length and weight were significantly increased after intake of standard feed containing 1% SBA. In parallel, the expressions of alkaline phosphatase and growth-related factors in bone, liver, and muscle of 1% SBA-fed fishes were markedly increased, suggesting the beneficial effects of SBA. The composition of amino acid and fatty acid in fish muscle, after intaking 1% SBA-containing feed, was altered. In SBA-fed fish muscle, the amounts of threonine and methionine were increased, while the amount of leucine was decreased, as compared with control group. The amounts of fatty acids, including docosahexaenoic acid, phosphatidylcholine, and phosphatidylethanolamine, were increased in the 1% SBA-fed fish, while the amounts of triglycerides were decreased. The results indicated the growth-promoting activity of SBA in an in vivo culture of S. fuscescens, as well as to increase the nutritive values of the muscle. Thus, the re-cycle of waste products during the farming of S. baicalensis herb in serving as fish feeding should be encouraged. © 2021 The Authors. Food Science & Nutrition published by Wiley Periodicals LLC.

The electron-deficient N-heteroaromatic polymers are crucial for the high-tech applications of organic materials, especially in the electronic and optoelectronic fields. Thus, the development of new polymerizations to afford adaptable electron donating-accepting scaffolds in N-heteroaromatic polymers is in high demand. Herein, metal-free multicomponent polymerizations of diynes, diamines and glyoxylates are successfully developed for in-situ generation of poly(quinoline)s with high molecular weights (Mw up to 16 900) in nearly quantitative yields. By tuning the electron distributions of the polymer backbones, the resulting poly(quinoline)s show various aggregation-induced behaviors and photo-responsive abilities. The thin films of poly(quinoline)s can be readily fabricated into well-resolved photopatterns by photolithography techniques. They can be utilized as fluorescent probes to directly visualize the morphologies of polymer materials including spherulites and microphase separation of polymer blends. Their nanoparticles demonstrate sensitive and highly selective fluorescence quenching to hexavalent chromium ion Cr(VI), which provides access for the biological imaging of Cr(VI) in unicellular algae.

A new cell line derived from dorsal fin of rabbit fish Siganus fuscescens was developed and characterized. The cell line was isolated from the dorsal fin, named as rabbit fish fin (RFF) cell line, and which was sub-cultured for 50 cycles since the development. This cell line was tested for growth in different temperatures and serum concentrations, and the best growing condition was at 20% serum at 28 °C. In cultured RFF cells, amplification of 18S rRNA from genomic DNA and immunostaining of cellular cytokeratin confirmed the proper identity of S. fuscescens fish. After 30th passage of cultures, the cells were exposed to challenge of inflammation, triggered by LPS, and hypoxia, mimicked by CoCl2. Cultured RFF cells showed robust sensitive responses to inflammation and hypoxia in directing the expressions of cytokines and hypoxia inducible factor-1α (HIF-1α). The water extract of aerial part of Scutellaria baicalensis (SBA) has been shown in rabbit fish to prevent inflammation. Here, we extended this notion of testing the efficacy of SBA extract in the developed cultured RFF cells. Application of SBA extract inhibited the expression of LPS-induced inflammatory cytokines, i.e. IL-1β, IL-6, as well as the signaling of NF-κB. The application of CoCl2 in cultured RFF cells triggered the hypoxia-induced cell death and up regulation of HIF-1α. As expected, applied SBA extract in the cultures prevented the hypoxia-induced signaling. Our results show the established RFF cell line may be served as an ideal in vitro model in drug screening relating to inflammation and hypoxia. Additionally, we are supporting the usage of SBA herbal extract in fish aquaculture, which possesses efficacy against inflammation and hypoxia.

The root of Scutellaria baicalnsis (Scutellaria Radix) is a medicinal part being used as a herbal drug; while its stem and leaf (aerial part) are considered as waste. Several reports have shown that aerial part of S. baicalnsis (SBA) has chemical similarity with its root, suggesting the possible usage of this non-medicinal part. Thus, the usage of SBA as an additive in aquaculture feeding could be a new way to recycle the waste. The water extract of SBA inhibited the growth of several common pathogenic bacteria in aquaculture, e.g. Aeromonas hydrophila, Edwardsiella tarda, Vibrio alginolyticus and Vibrio harveyi. In cultured macrophage cells (RAW 264.7), application of SBA extract showed strong anti-inflammation effect, which inhibited the expression of inflammatory cytokine, i.e. IL-1β, as induced by LPS. Similarly, SBA extract suppressed the LPS-induced transcriptional activity mediated by NF-κB. When applied in fish aquaculture, the extract of SBA was mixed into the feedings of Siganus fuscescens (rabbit fish) that was cultured with a mixture of pathogenic bacteria. The expression levels of COX-2, IL-1β and TNF-α were markedly reduced in the present of SBA extract. Our investigations show the anti-bacterial effect of SBA extract, as well as its potential anti-inflammation effects both in vitro and in vivo, which therefore suggest the possible development of S. baicalnsis aerial part in fish aquaculture.

Tissue regeneration is a crucial self-renewal capability involving many complex biological processes. Although transgenic techniques and fluorescence immunohistochemical staining have promoted our understanding of tissue regeneration, simultaneous quantification and visualization of tissue regeneration processes is not easy to achieve. Herein, we developed a simple and quantitative method for the real-time and non-invasive observation of the process of tissue regeneration. The synthesized ratiometric aggregation-induced-emission (AIE) probe exhibits high selectivity and reversibility for pH responses, good ability to map lysosomal pH both in vitro and in vivo, good biocompatibility and excellent photostability. The caudal fin regeneration of a fish model (medaka larvae) was monitored by tracking the lysosomal pH change. It was found that the mean lysosomal pH is reduced during 24-48 hpa to promote the autophagic activity for cell debris degradation. Our research can quantify the changes in mean lysosomal pH and also exhibit its distribution during the caudal fin regeneration. We believe that the AIE-active lysosomal pH probe can also be potentially used for long-term tracking of various lysosome-involved biological processes, such as tracking the stress responses of tissue, tracking the inflammatory responses, and so on. This journal is © The Royal Society of Chemistry.

Oysters accumulate high concentrations of zinc (Zn) and copper (Cu), which can be transferred to human due to sea food consumption. Breeding new oyster varieties with low Zn and Cu accumulations is one important way to improve food safety. However, the genetic basis for metal accumulation in mollusks is not well understood. To address this issue, oysters collected in the field were used for genome-wide association study (GWAS) and then the identified genes were used for mRNA expressions analysis in laboratory. First, GWAS were conducted for Zn and Cu accumulation in 288 wild Pacific oysters (Crassostrea gigas) farmed in the same ocean environment. The oysters did not show obvious population structure or kinship but exhibited 8.43- and 10.0- fold changes of Zn and Cu contents respectively. GWAS have identified 11 and 12 single nucleotide polymorphisms (SNPs) associated with Zn and Cu, respectively, as well as 16 genes, which were Zn-containing proteins or participated in caveolae-dependent endocytosis. Second, the mRNA expressions of these 16 genes were observed under Zn and Cu exposure. After 9 days of Zn exposure, Zn contents increased 3.1-fold, while the mRNA expression of cell number regulator 3 increased 1.65-fold. Under 9 days of Cu exposure, Cu contents increased 1.97-fold, while the mRNA expression of caveolin-1 decreased 0.61-fold. These provide the evidence for their roles in regulating physiological levels of these two metals. The findings advance our understanding of the genetic basis of Zn and Cu accumulation in mollusks, which can be useful for breeding new, less toxic varieties of oysters.

The estuarine oysters Crassostrea hongkongensis hyper-accumulate many metals and survive under high levels of metal exposure. In the present study, three natural populations of oysters with various levels of accumulated metals (mainly Cu and Zn) were collected from Southern China. The morphological characteristics and metal concentrations revealed their phenotypic differentiation. Further transcripts sequences acquired from their gill tissues were analyzed and 44,801 genes (with effective reads) were obtained via de novo assembly. The principal component analysis (PCA) revealed that the gene expression patterns also displayed differentiation among the three populations. A total of 3,199 differentially expressed genes (DEGs) was identified in the contaminated oysters as compared to the ‘clean’ oysters, which were used to explain the molecular mechanisms of metal accumulation and toxicity. GO and KEGG enrichment analysis revealed that energy production and cytoskeleton metabolism-related genes were particularly enriched in the contaminated sites during chronic metal exposure. Besides, increasing expressions of Zn/Cu transporters and metallothionein may explain their high accumulation in contaminated populations. We showed that oysters with less metal accumulation tended to cope with metal stress actively, but severe contamination destroyed part of the normal function. Our study analyzed the gene expression patterns of C. hongkongensis in Southern China and demonstrated the phenotypic differentiation of oysters under chronical metal exposure in the field.

The prevalence of silver nanoparticles (AgNPs) requires a comprehensive understanding of their biological impacts especially in marine and estuarine environments. Nevertheless, the background Ag concentration in organisms may impede the accuracy of Ag detection if the net accumulated Ag is low over a short exposure period. Here, a radio-synthesizing method was employed to trace the behavior of AgNPs with two sizes (15 and 60 nm) and two coatings (humic acid and citrate) in an estuarine oyster Crassostrea hongkongensis. This method was sensitive to detect the bioaccumulation and depuration of AgNPs in the oysters over a short period of exposure, which was necessary given the significant changes of particle aggregation in saline water environments. Through radioactive AgNP tracing and biokinetic modeling, we for the first time demonstrated the differential uptake mechanisms of different-sized AgNPs in oysters. Specifically, the ingestion of particles dominated the uptake of 60 nm AgNPs, whereas dermal uptake and ingestion contributed equally to 15 nm AgNPs. Surface coating (humic acid vs citrate) did not significantly affect the uptake of AgNPs by the oysters. The depuration of AgNPs from the oysters was relatively faster than that for the Ag ion. The digestive gland was the key detoxification organ of AgNPs with the greatest loss of Ag by the end of depuration. The findings of this study provide fundamental knowledge for nano-specific risk assessment in marine and estuarine environments. © 2019 American Chemical Society.