The world at large is facing a new threat with the emergence of the Coronavirus Disease 2019 (COVID-19) pandemic. Though imperceptible by the naked eye, the medical, sociological and economical implications caused by this newly discovered virus have been and will continue to be a great impediment to our lives. This health threat has already caused over two million deaths worldwide in the span of a year and its mortality rate is projected to continue rising. In this review, the potential of algae in combating the spread of COVID-19 is investigated since algal compounds have been tested against viruses and algal anti-inflammatory compounds have the potential to treat the severe symptoms of COVID-19. The possible utilization of algae in producing value-added products such as serological test kits, vaccines, and supplements that would either mitigate or hinder the continued health risks caused by the virus is prominent. Many of the characteristics in algae can provide insights on the development of microalgae to fight against SARS-CoV-2 or other viruses and contribute in manufacturing various green and high-value products.
Congracilaria babae was first reported as a red alga parasitic on the thallus of Gracilaria salicornia based on Japanese materials. It was circumscribed to have deep spermatangial cavities, coloration similar to its host and the absence of rhizoids. We observed a parasitic red alga with morphological and anatomical features suggestive of C. babae on a Hydropuntia species collected from Sabah, East Malaysia. We addressed the taxonomic affinities of the parasite growing on Hydropuntia sp. based on the DNA sequence of molecular markers from the nuclear, mitochondrial and plastid genomes (nuclear ITS region, mitochondrial cox1 gene and plastid rbcL gene). Phylogenetic analyses based on all genetic markers also implied the monophyly of the parasite from Hydropuntia sp. and C. babae, suggesting their conspecificity. The parasite from Hydropuntia sp. has a DNA signature characteristic to C. babae in having plastid rbcL gene sequence identical to G. salicornia. C. babae is likely to have evolved directly from G. salicornia and subsequently radiated onto a secondary host Hydropuntia sp. We also recommend the transfer of C. babae to the genus Gracilaria and propose a new combination, G. babae, based on the anatomical observations and molecular data.
Carbohydrate sulfotransferases (CHSTs) play a vital role in the production of sulfated polysaccharides (SPs) in algae by catalyzing the sulfation of carbohydrate moieties through the transfer of a sulfuryl group from the donor, 3'-phosphoadenosine 5'-phosphosulfate (PAPS). In the present study, putative algal CHSTs with a PF00685, PF03567. PF06990 and PF13469 domain were identified by HMMER search and Protein Basic Local Alignment Search Tool (BLAST) using the well-characterized human CHSTs as queries. Approximately half of the algal CHSTs that contained a PF00685 domain also possessed a PF13469 domain in an overlapping region. These CHSTs were structurally and phylogenetically distinct from algal CHSTs containing PF03567 or/and PF06990 domains. The PF00685/PF13469 domain is commonly found in Chlorophyta, while PF03567 and PF06990 domains are more prevalent in red algae and brown algae, respectively, reflecting the different types of SPs produced by these distinct phyla. Our phylogenetic analyses of algal CHSTs support the hypothesis of a polyphyletic origin, suggesting complex evolutionary histories involving both lineage-specific evolution and significant horizontal gene transfer (HGT) events between algae and organisms from other diverse taxa, including bacteria. In addition, the specificities of algal CHSTs for different carbohydrate moieties and site-specific sulfation patterns were inferred from the phylogenies of human CHSTs and the CHSTs from of algae with known SPs and chemical structures. This approach helps us to bridge the gap in knowledge, as a limited number of algal CHSTs have been biochemically characterized experimentally.
DNA barcoding has been a major advancement in the field of taxonomy, seeing much effort put into the barcoding of wide taxa of organisms, macro and microalgae included. The mitochondrial-encoded cox1 and plastid-encoded rbcL has been proposed as potential DNA barcodes for rhodophytes, but are yet to be tested on the commercially important carrageenophytes Kappaphycus and Eucheuma. This study gauges the effectiveness of four markers, namely the mitochondrial cox1, cox2, cox2-3 spacer and the plastid rbcL in DNA barcoding on selected Kappaphycus and Eucheuma from Southeast Asia. Marker assessments were performed using established distance and tree-based identification criteria from earlier studies. Barcoding patterns on a larger scale were simulated by empirically testing on the commonly used cox2-3 spacer. The phylogeny of these rhodophytes was also briefly described. In this study, the cox2 marker which satisfies the prerequisites of DNA barcodes was found to exhibit moderately high interspecific divergences with no intraspecific variations, thus a promising marker for the DNA barcoding of Kappaphycus and Eucheuma. However, the already extensively used cox2-3 spacer was deemed to be in overall more appropriate as a DNA barcode for these two genera. On a wider scale, cox1 and rbcL were still better DNA barcodes across the rhodophyte taxa when practicality and cost-efficiency were taken into account. The phylogeny of Kappaphycus and Eucheuma were generally similar to those earlier reported. Still, the application of DNA barcoding has demonstrated our relatively poor taxonomic comprehension of these seaweeds, thus suggesting more in-depth efforts in taxonomic restructuring as well as establishment.