Identification, Characterization, and Expression Analysis of Spondin-Like and Fasciclin-Like Genes in Neopyropia yezoensis, A Marine Red Alga

Extracellular matrix (ECM) proteins play crucial roles in the regulation of cell proliferation and differentiation. We identified homologous genes encoding ECM proteins that are known to associate with integrins in animal cells in red macroalga Neopyropia yezoensis. Four genes encoding spondin domain-containing proteins (NySPLs) and eight genes encoding fasciclin domain-containing proteins (NyFALs) from N. yezoensis were selected for bioinformatics and expression analysis in order to obtain insights into the roles of ECM proteins for the life cycle. NySPLs had eight β-strands with two contiguous α-helices, which were similar to those of the F-spondin domain of animals. NyFALs had conserved H1 and H2 motifs and a YH motif between the H1 and H2 regions. Quantitative reverse transcription polymerase chain reaction showed that NySPL1–3 and NyFAL8 transcripts were highly accumulated in mature gametophytes that formed the spermatia. Furthermore, expressions of all NySPLs were upregulated in response to the ethylene precursor 1-aminocylopropane-1-carboxylic acid that induces gametogenesis. NyFAL1, 4 were highly expressed in sporophytes, whereas NyFAL2, 3, 5, 6, and 7 were overexpressed in gametophytes, especially at the vegetative stage. These findings facilitate future research on ECM architecture in the unique life cycles of red macroalgae.

eDNA metabarcoding for diet analyses of green sea turtles (Chelonia mydas)

Understanding sea turtle diets can help conservation planning, but their trophic ecology is complex due to life history characteristics such as ontogenetic shifts and large foraging ranges. Studying sea turtle diet is challenging, particularly where ecological foraging observations are not possible. Here, we test a new minimally invasive method for the identification of diet items in sea turtles. We fingerprinted diet content using DNA from esophageal and cloacal swab samples by metabarcoding the 18S rRNA gene. This approach was tested on samples collected from green turtles (Chelonia mydas) from a juvenile foraging aggregation in the Bijagós archipelago in Guinea-Bissau. Esophagus samples (n = 6) exhibited a higher dietary richness (11 ± 5 amplicon sequence variants (ASVs) per sample; average ± SD) than cloacal ones (n = 5; 8 ± 2 ASVs). Overall, the diet was dominated by red macroalgae (Rhodophyta; 48.2 ± 16.3% of all ASVs), with the main food item in the esophagus and cloaca being a red alga belonging to the Rhodymeniophycidae subclass (35.1 ± 27.2%), followed by diatoms (Bacillariophyceae; 7.5 ± 7.3%), which were presumably consumed incidentally. Seagrass and some invertebrates were also present. Feeding on red algae was corroborated by field observations and barcoding of food items available in the benthic habitat, validating the approach for identifying diet content. We conclude that identification of food items using metabarcoding of esophageal swabs is useful for a better understanding of the relationships between the feeding behavior of sea turtles and their environment.

Physiological and Transcriptome Analysis of Exogenous L-Arginine in the Alleviation of High-Temperature Stress in Gracilariopsis lemaneiformis

Gracilariopsis lemaneiformis (G. lemaneiformis) is an important marine red macroalgae with high economic and ecological value all over the world. To date, global warming is a key issue that has a great impact on all living organisms, such as macroalgae. L-arginine (Arg) is a precursor of nitric oxide (NO) and polyamines (PAs), which can induce stress defense responses in land plants. However, its role in inducing algae resistance at high temperature (HT) is unclear. In this study, G. lemaneiformis thalli were treated with different concentrations of Arg to investigate its effect and the mechanism on the tolerance of G. lemaneiformis against HT stress. It turned out that exogenous Arg significantly alleviated the HT-induced oxidative damage as indicated by a markedly decrease in malondialdehyde (MDA) content. Notably, Arg remarkably improved the relative growth rate (RGR) and phycobiliprotein (PBP) contents of G. lemaneiformis at HT. Moreover, Arg significantly elevated the activities of antioxidant enzymes, such as superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), to efficiently scavenge reactive oxygen species (ROS). In addition, it also promoted the accumulation of free amino acids (AAs) as compared to those in the control treatment (CK) group under HT conditions. To investigate the mechanism of G. lemaneiformis to Arg, a transcriptome analysis was performed and revealed 1,414 and 3,825 differentially expressed genes (DEGs) in Arg-treated groups as compared to CK groups at 24 and 48 h of HT stress, respectively. Results showed that Arg significantly upregulated the expression of genes encoding antioxidant enzymes, heat shock proteins, and triggered transcription factors (TFs) signaling during HT stress. Moreover, Arg enhanced the DEGs involved in arginine and proline (Pro) metabolism, AAs biosynthesis, glycolysis, tricarboxylic acid (TCA) cycle, and oxidative phosphorylation. These results may help in understanding the role of Arg in G. lemaneiformis resistance to HT and provide a practical viewpoint for obtaining heat-tolerant G. lemaneiformis to further promote the development of the cultivated seaweed industry in the future.

Lipid characterization of 14 macroalgal species from Madeira Archipelago: implications for animal and human nutrition

The lipid and fatty acid profiles of 14 marine macroalgal species from the Madeira Archipelago, including two green (Ulvales and Dasycladales), three red (Corallinales, Bonnemaisoniales, and Ceramiales) and nine brown (Fucales, Dictyotales, and Sphacelariales) species were characterised in order to determine their potential use for animal and human nutrition. The total lipid content of species analysed was generally low, varying from 0.2 to 5.2% of dry weight. All species presented an omega 6/omega 3 (n-6/n-3) ratio lower than 10, as recommended by the World Health Organization for proper human health. Polyunsaturated fatty acids (PUFA), including linoleic acid and alpha-linolenic acid were exceptionally high in the green macroalga Ulva sp. Red macroalgae were rich in n-3 long-chain PUFA, particularly Asparagopsis taxiformis, which contained 6.6% of docosahexaenoic acid, and Halopithys incurva with 9.3% of eicosapentaenoic acid. Within Ochrophyta, Dictyota dichotoma is an interesting source of n-3 PUFA due to its high stearidonic acid proportion (8.0%). In addition, H. incurva contained a high proportion of both mono- and digalactosyldiacylglycerols. According to their lipid profiles, most macroalgae analysed might be considered of particular interest for their potential exploitation for human nutrition and livestock and aquaculture production.

Red Seaweed-Derived Compounds as a Potential New Approach for Acne Vulgaris Care

Acne vulgaris (AV) is a chronic skin disease of the pilosebaceous unit affecting both adolescents and adults. Its pathophysiology includes processes of inflammation, increased keratinization, sebum production, hormonal dysregulation, and bacterial Cutibacterium acnes proliferation. Common AV has been treated with antibiotics since the 1960s, but strain resistance has emerged and is of paramount concern. Macroalgae are known producers of substances with bioactive properties, including anti-viral, antibacterial, antioxidant, and anti-inflammatory properties, among several others. In particular, red algae are rich in bioactive compounds such as polysaccharides, phenolic compounds, lipids, sterols, alkaloids, and terpenoids, conferring them antioxidant, antimicrobial, and anti-inflammatory activities, among others. Thus, the exploration of compounds from marine resources can be an appealing approach to discover new treatment options against AV. The aim of this work is to provide an overview of the current knowledge of the potentialities of red macroalgae in the treatment of AV by reviewing the main therapeutic targets of this disease, and then the existence of compounds or extracts with bioactive properties against them.

Optimization of chlorophyll extraction solvent of bulung sangu (Gracilaria sp.) seaweed

Algae are a photosynthetic organism, affordable and naturally rich in nutrients and a valuable source of bioactive substances such as natural pigments. Bulung sangu (Gracilaria sp.) is red macroalgae that wildly grows and distributes in Bali. The aim of this work was to optimize the solvent to extract the chlorophyll content of Bulung sangu. The pigment extraction was carried out using different solvents (100% methanol, 100% ethanol, and 90% acetone). The chlorophyll contents including chlorophyll a,b,c,d and total chlorophyll were measured using spectrophotometry UV-VIS and expressed in µg/g of algae. The results showed that chlorophyll c could not be extracted using all used solvent, while chlorophyll b can only be extracted using acetone. Acetone produced the highest concentration of chlorophyll a (717.52 ± 9.71 µg/g), chlorophyll b (7.23 ± 0.24 µg/g), chlorophyll d (21.93 ± 1.07 µg/g), and chlorophyll total (746.67 ± 8.99 µg/g) compared to other solvent, that were significantly different (p<0.05). The second solvent to produce the highest concentration of chlorophyll a, d, and total chlorophyll was methanol which produced 578.77 ± 9.74 µg/g, 5.50 ± 0.12 µg/g and 584.27 ± 9.62 µg/g of chlorophyll content, respectively, followed by ethanol which produced 520.98 ± 2.52 µg/g of chlorophyll a, 3.56 ± 0.25 µg/g for chlorophyll d, and 524.54 ± 2.30 µg/g for total chlorophyll. Acetone is considered the most effective solvent to extract the chlorophyll content of Bulung sangu.