Life cycle of <Emphasis Type="Italic">Dilophus okamurae</Emphasis> (Phaeophyceae) and its associated invertebrate fauna in Onagawa Bay,Japan

ABSTRACT:   The life cycle of Dilophus okamurae and the associated benthic invertebrate fauna were studied monthly or bimonthly from June 1998 to September 1999 at a depth of 4–7 m in Onagawa Bay along the Pacific coast of north-eastern Honshu, Japan (38°28'N, 149°29'E). Dry biomass ranged from 230 g/m² in June to 10 g/m² in October. Sporophytes with tetrasporangia appeared during July to September 1998. Gametophytes with oogonia or antheridia were observed for the first time in May 1999 during observation. The absence of mature sporophytes in 1999 suggests that the life cycle is completed over two years. The sympatric gastropods Lirularia iridescens , Homalopoma sangrarense, Conotalopia minima and Cantharidus callichroa synchronized with seasonal changes in biomass of this algae. In contrast, Barleeia angustata and B. trifasciata fluctuated independently. The juvenile sea urchin Strongylocentrotus nudus appeared in the algal population starting in October at 0.7 mm mean test diameter at high density, and disappeared after March.     

Ishophloroglucin A,Isolated from Ishige okamurae,Alleviates Dexamethasone-Induced Muscle Atrophy through Muscle Protein Metabolism In Vivo

The in vitro capacity of Ishige okamurae extract (IO) to improve impaired muscle function has been previously examined. However, the mechanism underlying IO-mediated muscle protein metabolism and the role of its component, Ishophloroglucin A (IPA), in mice with dexamethasone (Dexa)-induced muscle atrophy remains unknown. In the present study, we evaluated the effect of IO and IPA supplementation on Dexa-induced muscle atrophy by assessing muscle protein metabolism in gastrocnemius and soleus muscles of mice. IO and IPA supplementation improved the Dexa-induced decrease in muscle weight and width, leading to enhanced grip strength. In addition, IO and IPA supplementation regulated impaired protein synthesis (PI3K and Akt) or degradation (muscle-specific ubiquitin ligase muscle RING finger and atrogin-1) by modulating mRNA levels in gastrocnemius and soleus muscles. Additionally, IO and IPA upregulated mRNA levels associated with muscle growth activation (transient receptor potential vanilloid type 4 and adenosine A1 receptor) or inhibition (myostatin and sirtuin 1) in gastrocnemius and soleus muscle tissues of Dexa-induced mice. Collectively, these results suggest that IO and IO-derived IPA can regulate muscle growth through muscle protein metabolism in Dexa-induced muscle atrophy.     

Diterpenoids from the Brown Alga Rugulopteryx okamurae and Their Anti-Inflammatory Activity

Brown algae of the Family Dictyotaceae produce an array of structurally diverse terpenoids, whose biomedical potential in the anti-inflammatory area has been scarcely explored. Herein, the chemical study of the alga Rugulopteryx okamurae has led to the isolation of ten new diterpenoids: rugukadiol A (1), rugukamurals A–C (2–4), and ruguloptones A–F (6–10). The structures of the new compounds were established by spectroscopic means. Compound 1 exhibits an unprecedented diterpenoid skeleton featuring a bridged tricyclic undecane system. Compounds 2–10 belong to the secospatane class of diterpenoids and differ by the oxygenated functions that they contain. In anti-inflammatory assays, the new diterpenoid 1 and the secospatanes 5 and 10 significantly inhibited the production of the inflammatory mediator NO in LPS-stimulated microglial cells Bv.2 and macrophage cells RAW 264.7. Moreover, compounds 1 and 5 were found to strongly inhibit the expression of Nos2 and the pro-inflammatory cytokine Il1b in both immune cell lines.     

Evaluating the vulnerability of coralligenous epifauna to macroalgal invasions

1. This work constitutes the first comprehensive study of the epifaunal response to biological invasions in coralligenous habitats, which are one of the main hotspots of biodiversity in the Mediterranean.
2. The epifaunal community inhabiting the invasive macroalga Rugulopteryx okamurae and other dominant sessile hosts on coralligenous habitats (i.e. the sponge Spongia lamella, the gorgonian Paramuricea clavata, and the macroalga Sphaerococcus coronopifolius) was characterized. A total of 137 taxa were found.
3. There was a lack of functional equivalence between macroalgal species (both native and invasive) and sessile invertebrates. Despite the absence of significant differences in mean density values and number of species per replicate among host species, epifaunal composition on gorgonians and sponges differed significantly from that on both macroalgae.
4. Epifaunal assemblages, especially those inhabiting macroalgal species, were dominated by generalist detritivorous species that can inhabit different hosts, while specialized interactions between mobile epifauna and sessile hosts were observed almost exclusively on sessile invertebrates. Moreover, epifaunal community associated with invertebrate hosts showed higher spatial heterogeneity in comparison with native and invasive macroalgae.
5. A competitive displacement of native hosts by the spreading of R. okamurae on coralligenous habitats would likely result in a biotic impoverishment in terms of overall number of species and a taxonomical and functional homogenization of the epifaunal community. Specialist species with a heterogeneous distribution could be gradually replaced by a spatially homogeneous assemblage dominated by generalist species.