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Marine algae, a rich source of bioactive substances, have long been utilized in biomedical and veterinary sciences. This study breaks new ground by assessing the antiviral therapeutic potential of water extracts from four algal species – Colaconema formosanum, Caulerpa microphysa, Gelidium amansii and Sarcodia suae – against vesicular stomatitis virus (VSV) infection. The standout among these was Sarcodia suae water extract (SSWE), which not only significantly repressed VSV replication and enhanced cell survival without cytotoxic effects, but also demonstrated its antiviral activity through interference with viral attachment, entry, RNA replication, and egress, and reduced VSV-induced autophagy in Mv1Lu cells during the late stages of infection. The EC50 of SSWE was 0.422 ± 0.14 mg ml‒1. The cytotoxicity assay confirmed the high biocompatibility of SSWE. This study identifies SSWE as a promising natural antiviral agent and elucidates its mechanisms of action, highlighting the need for further research to optimize its use in controlling VSV-related diseases. Highlights: The bioactive water extract of Sarcodia suae was identified as a sustainable antiviral agent for the algal cultivation industry. The antiviral activity of S. suae against vesicular stomatitis virus (VSV) infection was confirmed. The mechanisms of action of the extract from Sarcodia suae on the autophagic pathway were demonstrated. [ABSTRACT FROM AUTHOR]

Among the minority seawater species in the ornamental fish market, clownfish (Amphiprion ocellaris) have a high market value due to their vibrant appearance. Astaxanthin, a promising coloring agent, is applied in diets as a food additive to enhance the physical appearance of clownfish. However, as the retail price of astaxanthin has been inflating, the industry is eager to find more affordable astaxanthin products. The present study evaluated the nutrients and pigmentation performance of the algae-extracted astaxanthin diets of clownfish, followed by a comparative feeding trial evaluating the graded levels of either Haematococcus pluvialis powder or extracted astaxanthin supplements in the experimental diets. The study included three stages: assessing the utilization of H. pluvialis powder as an astaxanthin source, investigating the optimal practical extraction method, and revisiting the effects of crude extracted astaxanthin on clownfish based on the identified preparation processes. In the first stage, H. pluvialis powder was applied as the feed additive for a feeding trial, resulting in a low-utilization rate of astaxanthin in clownfish. This indicated that a suitable extraction method was essential for clownfish. Two chemical-based methods for astaxanthin extraction were investigated to obtain the optimal extraction yields; results showed that the HCl–acetone method had an astaxanthin yield of 21.99 ± 0.52 mg/g cell, which was significantly higher than the yield from the acetic acid-DMSO method. Finally, the effects of HCl–acetone-extracted astaxanthin was compared with the effects of synthesized astaxanthin. The pigmentation performance study was performed using a digital image acquisition and processing technique. A significant increase in the red color signal was observed at week six after fed with 400 and 200 mg/kg of the extracted astaxanthin, compared to the control 0 mg/kg. In conclusion, H. pluvialis-extracted astaxanthin following the HCl–acetone method can significantly improve the pigmentation performance of A. ocellaris after 42 days of oral administration. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the growth and spawning characteristics of wild Channa lucius (Cuvier, 1831) populations in the Mekong Delta, Vietnam. The study was carried out from March 2011 to February 2012. The length–weight relationship of C. lucius was determined according to the equations W = 0.0044L3.2494, R2 = 0.9157 (female fish) and W = 0.0047L3.2178, R2 = 0.9434 (male fish). The length and weight of the body for female fish ranged from 16.3 to 36.0 cm and 49.0 to 550.0 g, and for male fish, from 14.6 to 38.2 cm and 46.0 to 639.0 g, respectively. Female and male fish had almost similar lengths at first maturity (21.3958 cm for females and 21.3952 cm for males). The condition factor of female fish ranged from 0.842 to 0.864 and for male fish ranged from 0.848 to 0.874. The gonadosomatic index of female fish was highest in June (1.68%) and lowest in November (0.69%); that of male fish was highest in June (0.53%) and lowest in September (0.15%). The sexual maturity rate (SMR) of female fish peaked in May, with SMRs of 33.3% (stage III) and 58.3% (stage IV). In conclusion, C. lucius has a positive allometric range (b > 3), reaching sexual maturity when its length reaches 21.39 cm for both sexes, and the spawning season begins in December but peaks in May and June. [ABSTRACT FROM AUTHOR]

Algal susceptivity to inorganic arsenate As(V) is linked to the plant nutrient phosphate due to their similar uptake processes. This study determines the response of Sarcodia suae to three phosphate concentrations (1, 10 and 20 mg l–1) when exposed to As(V) (0, 250 µg l–1) for 7 days. The parameters measured include growth, pigments (Chlorophyll a (Chl a), allophycocyanin (APC), phycocyanin (PC), phycoerythrin (PE), total phycobiliproteins (TPBP) and carotenoids), inorganic arsenic (iAs), and total arsenic (TAs) uptake behaviour and bioaccumulation capacity. The growth rate showed significant differences among treatments. Significantly higher levels of pigments including Chl a and carotenoids were observed with an increase in external phosphate concentrations. On the other hand, APC, PC, PE and TPBP showed no significant differences among treatments. The trend of iAs and TAs uptake when phosphate is high suggests competition between phosphate and As(V) as is evident from the reduction of uptake with increased phosphate. The depletion of phosphate and As(V) in the medium also suggests accumulation by the algae. In addition, S. suae was considered an As accumulator but not a hyperaccumulator as defined on its bioaccumulation capacity of 48 and 97 mg kg–1 of iAs and TAs, respectively. Overall, these findings suggest that environmental factors including levels of phosphate have a key role in developing effective As bioremediation in the environment. Highlights Phosphate in Sarcodia suae probably regulates arsenic uptake. Photosynthetic pigments can be linked to competitive mechanisms of As(V). The red alga Sarcodia suae is a candidate for As wastewater treatments by Bioconcentration Factor analysis. [ABSTRACT FROM AUTHOR]