Agelasine Diterpenoids and Cbl-b Inhibitory Ageliferins from the Coralline Demosponge Astrosclera willeyana

An extract of the coralline demosponge Astrosclera willeyana inhibited the ubiquitin ligase activity of the immunomodulatory protein Cbl-b. The bioassay-guided separation of the extract provided ten active compounds, including three new N-methyladenine-containing diterpenoids, agelasines W–Y (1–3), a new bromopyrrole alkaloid, N(1)-methylisoageliferin (4), and six known ageliferin derivatives (5–10). The structures of the new compounds were elucidated from their spectroscopic and spectrometric data, including IR, HRESIMS, and NMR, and by comparison with spectroscopic data in the literature. While all of the isolated compounds showed Cbl-b inhibitory activities, ageliferins (4–10) were the most potent metabolites, with IC₅₀ values that ranged from 18 to 35 μM.     

A successful microbound diet for the larval culture of freshwater prawn Macrobrachium rosenbergii

A high moisture (63–71%), semi-purified microbound diet containing alginate was compared to newly hatched live Artemia nauplii as an exclusive diet for the culture of larval freshwater prawn Macrobrachium rosenbergii from 5th stage (weighted mean) through metamorphosis to postlarva. Two separate trials, representing larvae from different hatches, were conducted. Larvae were stocked at 50/l into cone-shaped vessels that contained 2 l of 12‰ seawater and were part of a temperature-controlled (28 °C) recirculating culture system. Larvae were manually fed either the live Artemia diet or the microbound diet exclusively, several times daily. After 14 days (23 days post-hatch (dph)), growth of larvae fed the microbound diet was 90% of that achieved for larvae fed newly hatched nauplii of Artemia. Survival of larvae fed the microbound diet was 77.3% and 73.3%, and was not significantly different from that of Artemia-fed larvae. Composed of readily available ingredients, the diet contains 46.2% crude protein and 37.4% lipid, is easy to prepare, and has good water stability. The diet is an economically practical alternative to the fluctuating cost, nutrient uncertainty, and labor associated with the use of Artemia nauplii hatched from cysts. The characteristics of the diet suggest good potential for successful use in the larviculture of other fish and crustacean species, in either the existing or a modified state.     

The structure of microbial communities in redoximorphic microsites of Gleysol

Microbial communities were studied in redoximorphic microsites of highly heterogeneous Gleysol at a mm scale using 16S and 18S amplicon sequencing to demonstrate if the composition of soil microbes reflects the differences in ferric and ferrous micro-sites. In both explored gley horizons with redoximorphic features (Bg2 and Cg), ferric mottles were significantly enriched with total P and Fe and depleted of O, Si, Al, K and Ca compared with the adjacent ferrous groundmass (SEM–EDS). Ferric mottles were determined as Fe oxide coatings and hypocoatings. In Bg2, both prokaryotic and micro-eukaryotic communities differed significantly between mottles and groundmass in composition of operational taxonomic units (OTUs) and in proportions of phyla, reflecting heterogeneities in the soil properties there. Mottles in Bg2 were characterized by increased proportion of Proteobacteria, decreased proportion of Acidobacteriota among prokaryotes and by dominance of a single proteobacterial OTU from Anaplasmataceae compared to all other samples. The composition of micro-eukaryotes showed an opposite trend, as micro-eukaryotes of Bg2 groundmass were unique among the other horizons, while micro-eukaryotes of Bg2 mottles had similar composition to neighbouring horizons. Microbial communities of adjacent samples were not more similar to each other than communities of randomly selected ones in Bg2 horizon. That suggests that at mm scale, the sample distance does not represent the driving factor of microbial community composition and that the adjacent samples differ rather due to physicochemical factors. The spatial organization of microbial communities revealed in Bg2 has not reappeared in similarly organized Cg horizon, probably due to other overriding factors. The differences revealed between Bg2 and Cg horizons, including granulometric composition, content of crystalline Fe, exchangeable Al, and organic carbon, as well as exposition to groundwater, were discussed as possible reasons of the distinct organization in Cg. The similarity of pro−/eukaryotic communities of adjacent and non-adjacent couples suggests no distance decay pattern at a mm scale. The agreement between patchiness in soil properties and microbial communities was revealed for the first time and confirms the importance of microscale patterns in soil.