No abstract

The serial remote sensing based imageries clearly revealed large scale of upwelling within large regional enhancement of chlorophyll‐a (Chl‐a) concentration in the southern East China Sea (ECS) after the passage of super typhoon Hai‐Tang in July 2005. After the typhoon on 22 July, the upwelling area (<26°C) expanded rapidly to 9146 km2 on the shelf‐break. The large increased upwelling persisted for more than a week. Ocean color images also reveled that high Chl‐a concentration of >3.0 mg/m3 appeared in the shelf region, where the high Chl‐a pattern matched the upwelling in terms of location and time. On the other hand, a large offshore SST cooling was also observed mainly to the right of typhoon track on 20 July, it lasted in a period of 2–3 days. This paper provides clear and high‐resolution evidence that typhoon significant increased upwelling and Chl‐a concentration in the southern ECS.

With the anti-microbial and anti-tumor composite screening model, bioassay-guided fractionation led to the isolation of two structurally related bioactive compounds, curvularin and alphabeta-dehydrocurvularin, from ethyl acetate extract of Eupenicillium sp. associated with marine sponge Axinella sp. Further study on the structure-activity relationship demonstrated that both compounds exhibited differences in bioactive profiles which are highly associated with their minor structural differences. Both curvularin and alphabeta-dehydrocurvularin have similar level of anti-fungal and anti-tumorous activity, while alphabeta-dehydrocurvularin is active against Staphylococcus aureus with a minimal inhibitory concentration of 375 microg/ml but curvularin does not. No detectable activity against Gram-negative bacteria such as Escherichia coli and Pseudomonas aeruginosa exists for both compounds. It is suggested that the partial planar backbone structure, due to the conjugation of pi electrons in the presence of a 3,4-double bond and the carbonyl group at position C-2 in alphabeta-dehydrocurvularin, acts as a key factor for the inhibition of S. aureus, a Gram-positive low G + C bacteria that are often the hospital-acquired and/or community-acquired pathogen.