Discrimination against 4-methyl sterol uptake during steryl chlorin ester production by copepods

Citation
Hm. Talbot et al., Discrimination against 4-methyl sterol uptake during steryl chlorin ester production by copepods, ORG GEOCHEM, 31(9), 2000, pp. 871-880
Citations number
27
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Earth Sciences
Journal title
ORGANIC GEOCHEMISTRY
ISSN journal
0146-6380 → ACNP
Volume
31
Issue
9
Year of publication
2000
Pages
871 - 880
Database
ISI
SICI code
0146-6380(2000)31:9<871:DA4SUD>2.0.ZU;2-3
Abstract
To investigate possible reasons for the discrepancy between the abundance o f 4-methyl components in free sterols and steryl chlorin esters (SCEs) whic h is commonly observed in sediments, experiments in which the copepod Calan us helgolandicus grazed on the dinoflagellates Prorocentrum micans and Alex andrium tamarense were carried out. With P. micans all the algal sterols we re esterified as SCEs in the faecal pellets, but there was clear discrimina tion against the uptake of 4-Me sterols. This discrimination was also evide nt with A. tamarense. To investigate changes in the faecal pellet SCE and t he free sterol distributions during pellet ageing in the P. micans experime nt, portions were allowed to stand for up to 29 days in seawater in the dar k. Although degradation of SCEs occurred, their esterified sterol distribut ion remained unchanged. The free sterols were degraded more rapidly than th e SCEs and changes in the distribution were observed. This provides further laboratory evidence that sedimentary SCE sterols are more robust markers o f phytoplankton communities than the corresponding free sterol distribution s. Comparison of the SCE abundance in sterilised and unsterilised pellets i ndicated that the degradation was a result of microbial activity. (C) 2000 Elsevier Science Ltd.. All rights reserved.