Linking molecular and population stress responses in Daphnia magna exposed to cadmium.
DNA microarrays can be used to measure environmental stress responses. If they are to be predictive of environmental impact, we need to determine if altered gene expression translates into negative impacts on individuals and populations. A large cDNA microarray (14000 spots) was created to measure molecular stress responses to cadmium in Daphnia magna,the mostwidely used aquatic indicator species, and relate responses to population growth rate (pgr). We used the array to detect differences in the transcription of genes in juvenile D. magna (24 h old) after 24 h exposure to a control and three cadmium concentrations (6, 20, and 37 microg Cd2+ L(-1)). Stress responses at the population level were estimated following a further 8 days exposure. Pgr was approximately linear negative with increasing cadmium concentration over this range. The microarray profile of gene expression in response to acute cadmium exposure begins to provide an overview of the molecular responses of D. magna, especially in relation to growth and development. Of the responding genes, 29% were involved with metabolism including carbohydrate, fat and peptide metabolism, and energy production, 31% were involved with transcription/translation, while 40% of responding genes were associated with cellular processes like growth and moulting, ion transport, and general stress responses (which included oxidative stress). Our production and application of a large Daphnia magna microarray has shown that measured gene responses can be logically linked to the impact of a toxicant such as cadmium on somatic growth and development, and consequently pgr.
Connon
Richard
R
School of Biological Sciences, University of Reading, P.O. Box 68, Reading RG6 6BX, UK.
Hooper
Helen L
HL
Sibly
Richard M
RM
Lim
Fei-Ling
FL
Heckmann
Lars-Henrik
LH
Moore
David J
DJ
Watanabe
Hajime
H
Soetaert
Anneleen
A
Cook
Katie
K
Maund
Steve J
SJ
Hutchinson
Thomas H
TH
Moggs
Jonathan
J
De Coen
Wim
W
Iguchi
Taisen
T
Callaghan
Amanda
A
D000818:Animals; D002104:Cadmium / Q000633:toxicity*; D003621:Daphnia / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development; D020869:Gene Expression Profiling; D020411:Oligonucleotide Array Sequence Analysis; D014874:Water Pollutants, Chemical / Q000633:toxicity*
D014874:Water Pollutants, Chemical; D002104:Cadmium