CLASSIFICATION OF THE GENUS ISHIGE (ISHIGEALES, PHAEOPHYCEAE) IN THE NORTH PACIFIC OCEAN WITH RECOGNITION OF ISHIGE FOLIACEA BASED ON PLASTID rbcl AND MITOCHONDRIAL cox3 GENE SEQUENCES(1)

Structural characterization of a sulfated polysaccharide from Ishige okamurae and its effect on recovery from immunosuppression

A sulfated polysaccharide from the brown alga Ishige okamurae Yendo, designated IOY, was successfully isolated by anion-exchange and size-exclusion chromatography. Chemical and spectroscopic analyses demonstrated that IOY was a fucoidan, that consisted of →3)-α-l-Fucp-(1→, →4)-α-l-Fucp-(1→, →6)-β-d-Galp-(1 → and →3)-β-d-Galp-(1 → residues with sulfate groups at C-2/C-4 the of (1 → 3)-α-l-Fucp and C-6 the of (1 → 3)-β-d-Galp residues. IOY possessed a potent immunomodulatory effect in vitro as measured by lymphocyte proliferation assay. The immunomodulatory effect of IOY was further investigated in vivo using immunosuppressed mice induced by cyclophosphamide (CTX). The results showed that IOY significantly increased the spleen and thymus indexes and alleviated CTX-induced spleen and thymus damage. Furthermore, IOY had a significant effect on hematopoietic function recovery and promoted the secretion of interleukin-2 (IL-2) and tumor necrosis factor (TNF-α). Notably, IOY reversed CD4+ and CD8+ T cell reduction and improved immune response. These data indicated that IOY had vital in immunomodulatory function and could be used as drug or functional food to lessen chemotherapy-induced immunosuppression.

A Proposal for the Lectotype Designation of Ishige foliacea (Phaeophyceae, Ishigeaceae) Using DNA Barcoding

Three species of the genus Ishige (Phaeophyceae, Ishigeaceae) are known from Korea, Japan and Mexico; they include Ishige foliacea Okamura, I. okamurae Yendo and I. sinicola (Setchell and N.L. Gardner) Chihara. Two species, I. foliacea and I. okamurae, are present in the algal flora of Korea and Japan. The original description of I. okamurae defined two forms of branches, filiform and foliose, but later the foliose branch was recognized as a new species I. foliacea, which is epiphytic on I. okamurae but can also be free-living. The currently proposed lectotype for I. foliacea is based on a free-living form and does not reflect the intent of the original description of the species. In this study, we conducted the DNA barcoding for herbarium specimens to identify Ishige species. Additionally, the variation in cox3 sequences obtained from I. okamurae specimens with two morphological forms collected from waters around the Korean Peninsula was sufficient to separate two species, I. okamurae and its epiphyte I. foliacea. The epiphytic I. foliacea on the lectotype specimen of I. okamurae is designated as lectotype I. foliacea.

The complete chloroplast genome of Ishige okamurae

Ishige okamurae plays an important role in marine ecosystem and biological resource utilization. The total length of chloroplast genome was 129,988 bp, containing a large single-copy region (LSC, 77,531 bp), a small single-copy region (SSC, 41,795 bp) and a pair of inverted repeat regions (IRs, 10,662 bp). The circular genome consisted of 101 protein-coding genes, 29 tRNA genes, and six rRNA genes, with a total of 136. Phylogenetic analysis confirmed the position of I. okamurae within the Phaeophyta.

Anti-Obesity and Anti-Diabetic Effects of Ishige okamurae

Obesity is associated with several health complications and can lead to the development of metabolic syndrome. Some of its deleterious consequences are related to insulin resistance, which adversely affects blood glucose regulation. At present, there is a growing concern regarding healthy food consumption, owing to awareness about obesity. Seaweeds are well-known for their nutritional benefits. The brown alga Ishige okamurae (IO) has been studied as a dietary supplement and exhibits various biological activities in vitro and in vivo. The bioactive compounds isolated from IO extract are known to possess anti-obesity and anti-diabetic properties, elicited via the regulation of lipid metabolism and glucose homeostasis. This review focuses on IO extract and its bioactive compounds that exhibit therapeutic effects through several cellular mechanisms in obesity and diabetes. The information discussed in the present review may provide evidence to develop nutraceuticals from IO.

Understanding the Evolution of Mitochondrial Genomes in Phaeophyceae Inferred from Mitogenomes of Ishige okamurae (Ishigeales) and Dictyopteris divaricata (Dictyotales)

To gain further insight into the evolution of mitochondrial genomes (mtDNAs) in Phaeophyceae, the first recorded characterization of an Ishigeophycidae mtDNA from Ishige okamurae (Yendo), and only the second recorded characterization of a Dictyotophycidae mtDNA from Dictyopteris divaricata (Okamura) Okamura are presented in this study. The 35,485 bp I. okamurae mtDNA contained 36 protein-coding genes (PCGs), 22 tRNAs, three rRNAs, and four open reading frames (orfs), and the 32,021 bp D. divaricata mtDNA harbored 35 PCGs, 25 tRNAs, three rRNAs, and three orfs. The A + T content in D. divaricata (61.69%) was the lowest recorded in sequenced brown algal mtDNAs. The I. okamurae mtDNA displayed unique genome features including an elevated start-codon usage bias for GTG, while the organization of D. divaricata mtDNA was identical to that of Dictyota dichotoma. Phylogenetic analysis based on the amino acid sequence dataset of 35 PCGs indicated that I. okamurae (Ishigeophycidae) diverged early from the Fucophycidae-Dictyotophycidae complex, which was confirmed by the comparative analysis of the mitogenome structure. The novel mitogenome data made available by this study have improved our understanding of the evolution, phylogenetics, and genomics of brown algae.