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Photoinhibition by visible and ultraviolet radiation in the red macroalga Porphyra umbilicalis grown in the laboratory (1999)

Häder, Donat-P. ; Gröniger, Almut ; Hallier, Caroline ; [et al.]

Springer

Plant ecology 145 (1999), S. 351-358

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ISSN: 1573-5052

Keywords: oxygen measurements ; PAM fluorescence ; photoinhibition ; Porphyra ; rhodophyta ; ultraviolet radiation

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Photosynthetic oxygen production and PAM fluorescence measurements were used to follow photoinhibition in the red macroalga Porphyra umbilicalis. Exposure to simulated solar radiation caused inhibition of the effective photosynthetic quantum yield from which the thalli partially recovered in the shade in subsequent hours. There were no significant differences between samples exposed to unfiltered radiation and those exposed to radiation from which increasing portions of UV radiation had been removed indicating that the thalli are well adapted to current levels of solar PAR and UV radiation. This notion was supported by the finding of high concentrations of UV screening pigments which were even enhanced by exposure to increased UV radiation. However, when exposed to (only) UV radiation about 50% higher than that encountered by the organisms in their natural habitat, the photosynthetic yield decreased slowly and did not show any recovery even when the degree of inhibition did not exceed 10%.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1009833520770

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Cytotoxic Triterpene Glycosides from Far-Eastern Sea Cucumbers Belonging to the Genus Cucumaria (1997)

Drozdova, Olga A. ; Avilov, Sergey A. ; Kalinin, Vladimir I. ; [et al.]

Weinheim : Wiley-Blackwell

Liebigs Annalen 1997 (1997), S. 2351-2356

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ISSN: 0947-3440

Keywords: Carbohydrates ; Cucumaria japonica ; Cucumaria miniata ; Sea cucumbers ; Cucumariosides ; Triterpene glycosides ; Antitumor activity ; Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: New cytotoxic triterpene oligoglycoside disulfates, cucumariosides A3 (1) and A6-2 (2), have been isolated from the sea cucumber Cucumaria japonica. The trisulfated cucumarioside A7-3 (4) was found to be the major component in the glycoside fraction of Cucumaria miniata. The structures were assigned on the basis of extensive spectral data (NMR and MS), selective solvolysis of desulfated derivative 3 and other chemical evidence. The presence or absence of a carbonyl group at C-16 of the aglycone and of sulfate groups at C-6 of the glucose and 3-O-methylglucose units are interpreted in terms of the functional evolution of sea cucumbers in order to improve their defensive system. Both (1) and (2) are cytotoxic in vitro at IC50 = 1 μg/ml against a selection of five human and mice tumoral cell lines.

Additional Material: 2 Ill.