Search Results (5)

The pigmentation and coloration of P. vannamei are primarily determined by the type and concentration of dietary carotenoids, with carotenoid-rich macroalgae serving as effective dietary supplements to enhance pigment accumulation and improve commercial quality. Five experimental diets were formulated with 3% brown algae (Saccharina japonica, SJ group; Sargassum fusiforme, SF group), red algae (Neoporphyra haitanensis, NH group), or 0.1% purified carotenoids (zeaxanthin, ZT group; fucoxanthin, FX group). The results showed that both macroalgae and carotenoid supplementation significantly enhanced weight gain rate (WGR) and specific growth rate (SGR) compared to the control group, with the zeaxanthin and fucoxanthin groups exhibiting the greatest improvements (1.6-fold and 1.3-fold, respectively). The N. haitanensis-supplemented diet, which had the highest carotenoid content, resulted in the most pronounced carotenoid accumulation (2.58-fold increase). Carotenoids were mainly deposited in the exoskeleton, followed by the hepatopancreas, with minimal accumulation in muscle tissue. α-Carotene and β-carotene contributed most to exoskeleton deposition, while lutein and zeaxanthin had weaker effects, and fucoxanthin showed no significant influence. Tissue-specific distribution patterns were observed: α-carotene and β-carotene were localized in the exoskeleton; fucoxanthin and zeaxanthin were found only in the exoskeleton and hepatopancreas, and astaxanthin was present in all three tissues. Furthermore, astaxanthin diesters (C20:5 and C22:6) were primarily detected in the exoskeleton and hepatopancreas, while monoesters (C16:0 and C18:0) were specific to muscle. These findings suggest that targeted supplementation of algal-derived carotenoids can enhance both growth and pigmentation in P. vannamei, providing a theoretical basis for the development of functional feeds to improve shrimp commercial quality. Full article

This work aims to determine the impact of dietary supplementation of polysaccharide, extracted from brown seaweeds Sargassum dentifolium on growth indices, feed utilization, biochemical compositions, microbial abundance, expressions of growth and immunity-related genes, and stress genes of the Pacific Whiteleg shrimp Litopenaeus vannamei. A total of 360 post-larvae of L. vannamei were randomly distributed into a 12-glass aquarium (40 L of each) at a stocking density of 30 shrimp with an initial weight of (0.0017 ± 0.001 g). During the 90-day experiment trial, all shrimp larvae were fed their respective diets at 10% of total body weight, three times a day. Three experimental diets were prepared with different seaweed polysaccharide (SWP) levels. The basal control diet had no polysaccharide level (SWP₀), while SWP₁, SWP₂, and SWP₃ contained polysaccharides at concentrations of 1, 2, and 3 g kg⁻¹ diet, respectively. Diets supplemented with polysaccharide levels showed significant improvements in weight gain and survival rate, compared to the control diet. Whole-body biochemical composition and the microbial abundance (the total count of heterotrophic bacteria and Vibrio spp.) of L. vannamei showed significant differences among polysaccharide-treated diets compared to the control. At the end of the feeding experiment, the dietary supplementation of polysaccharide levels enhanced the expression of growth-related genes (Insulin-like growth factors (IGF-I, IGF-II), immune-related genes (β -Glucan-binding protein (β-Bgp), Prophenoloxidase (ProPO), Lysozyme (Lys), and Crustin), and stress genes (Superoxide dismutase (SOD) and Glutathione peroxidase (GPx) in the muscle tissue of L. vannamei. However, the current study concluded that the inclusion rate of 2 g kg^–1 of polysaccharide as a dietary additive administration enhanced both weight gain and survival rate of L. vannamei, while the incorporation level of 3 g kg^–1 reduces the abundance of pathogenic microbes and enhances the growth-, immunity- and stress-related gene expressions of L. vannamei. Full article

A mutualistic symbiosis exists between the alga Sargassum spp. and two shrimp species, Latreutes fucorum and Leander tenuicornis. However, little is known about how these shrimp locate and establish their host alga. Both visual and chemical cues are potentially available. A previous study has looked at both cue variables with results that are mixed. Specifically, these same shrimp species used chemical cues only when visible cues were available simultaneously. Visual cues would be presumably restricted at night, but chemical cues are potentially available continuously. This current research elaborates on the previous study to fully understand Sargassum shrimp chemoreception. Increases in sample sizes and both a 4-chambered and Y-maze apparatus were used to test whether the shrimp could detect Sargassum cues, dimethylsulfoniopropionate (DMSP) (a chemical excreted by some marine algae), and conspecific cues. Neither shrimp species showed a strong directional response to any of the chemical cues, but the Sargassum and DMSP cues did cause more shrimp to exhibit searching behavior. Additionally, several differences in responses between male and female shrimp were found for each cue. A lowered dilution of DMSP was also tested to determine sensitivity of L. fucorum shrimp to the chemical cue; although searching behavior was triggered, conclusions about quantifying the sensitivity could not be made. Overall, these results show the shrimp can detect chemical cues—in the absence of visual cues—that could affect initiating and maintaining this shrimp/algal symbiosis. Full article

Four new indolediketopiperazine derivatives (1–4), along with nine known congeners (5–13), were isolated and identified from the culture extract of Eurotium cristatum EN-220, an endophytic fungus obtained from the marine alga Sargassum thunbergii. The structures of thesecompounds were elucidated on the basis of extensive spectroscopic analysis and the absolute configurations of compounds 1–4 were established by NOESY experiments and by chiral HPLC analyses of their acid hydrolysates. The absolute configuration of C-8 (a quaternary carbon substituted with a hydroxyl group) in 5 of preechinulin class was firstly determined by electronic circular dichroism (ECD) calculations. All these compounds were evaluatedfor brine shrimp (Artemia salina) lethality and nematicidal activity as well as antioxidativeand antimicrobial potency. Full article

Two new compounds, asperversin A (1) and 9ξ-O-2(2,3-dimethylbut-3-enyl)brevianamide Q (2), and nine known compounds, brevianamide K (3), brevianamide M (4), aversin (5), 6,8-di-O-methylnidurufin (6), 6,8-di-O-methylaverufin (7), 6-O-methylaverufin (8), 5α,8α-epidioxyergosta-6,22-dien-3β-ol (9), ergosta-7,22-diene-3β,5α,6β-triol (10), and 6β-methoxyergosta-7,22-diene-3β,5α-diol (11), were obtained from the culture of Aspergillus versicolor, an endophytic fungus isolated from the marine brown alga Sargassum thunbergii. The structures of these compounds were established by spectroscopic techniques. Compounds 4, 7 and 8 exhibited antibacterial activities against Escherichia coli and Staphyloccocus aureus, and 7 also showed lethality against brine shrimp (Artemia salina) with an LC₅₀ value of 0.5 μg/mL. Full article