title: Interspecific differences between D. pulex and D. magna in tolerance to cyanobacteria with protease inhibitors.
abstract: It is known that cyanobacteria negatively affect herbivores due to their production of toxins such as protease inhibitors. In the present study we investigated potential interspecific differences between two major herbivores, Daphnia magna and Daphnia pulex, in terms of their tolerance to cyanobacteria with protease inhibitors. Seven clones each of D. magna and of D. pulex were isolated from different habitats in Europe and North America. To test for interspecific differences in the daphnids' tolerance to cyanobacteria, their somatic and population growth rates were determined for each D. magna and D. pulex clone after exposure to varying concentrations of two Microcystis aeruginosa strains. The M. aeruginosa strains NIVA and PCC(-) contained either chymotrypsin or trypsin inhibitors, but no microcystins. Mean somatic and population growth rates on a diet with 20% NIVA were significantly more reduced in D. pulex than in D. magna. On a diet with 10% PCC(-), the population growth of D. pulex was significantly more reduced than that of D. magna. This indicates that D. magna is more tolerant to cyanobacteria with protease inhibitors than D. pulex. The reduction of growth rates was possibly caused by an interference of cyanobacterial inhibitors with proteases in the gut of Daphnia, as many other conceivable factors, which might have been able to explain the reduced growth, could be excluded as causal factors. Protease assays revealed that the sensitivities of chymotrypsins and trypsins to cyanobacterial protease inhibitors did not differ between D. magna and D. pulex. However, D. magna exhibited a 2.3-fold higher specific chymotrypsin activity than D. pulex, which explains the observed higher tolerance to cyanobacterial protease inhibitors of D. magna. The present study suggests that D. magna may control the development of cyanobacterial blooms more efficiently than D. pulex due to differences in their tolerance to cyanobacteria with protease inhibitors.
authors: Zoological Institute, Aquatic Chemical Ecology, University of Cologne, Cologne, Germany. meroder@gmx.de
authors: Christian J
authors: CJ
authors: Kuster
authors: Eric
authors: E
authors: Von Elert
mesh_terms: D000818:Animals; D060829:Arthropod Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D002918:Chymotrypsin / Q000037:antagonists & inhibitors / Q000737:chemistry; D003621:Daphnia / Q000201:enzymology* / Q000254:growth & development; D060434:Herbivory; D046931:Microcystis / Q000378:metabolism*; D013045:Species Specificity; D014357:Trypsin / Q000737:chemistry; D014361:Trypsin Inhibitors / Q000737:chemistry* / Q000378:metabolism
chemical_list: D060829:Arthropod Proteins; D001426:Bacterial Proteins; D014361:Trypsin Inhibitors; D002918:Chymotrypsin; D014357:Trypsin
references: Proc Biol Sci. 2010 Aug 7;277(1692):2381-7
references: 20356890
references: J Nat Prod. 2005 Sep;68(9):1324-7
references: 16180807
references: Appl Environ Microbiol. 1999 Feb;65(2):737-9
references: 9925609
references: Oecologia. 2013 May;172(1):11-20
references: 23053237
references: Genetics. 2009 May;182(1):313-23
references: 19299338
references: Oecologia. 2009 Mar;159(2):317-24
references: 19018574
references: BMC Physiol. 2010 May 04;10:6
references: 20441581
references: Mol Ecol. 2012 Oct;21(19):4898-911
references: 22943151
references: Environ Microbiol. 2006 Jan;8(1):77-87
references: 16343324
references: Environ Toxicol Chem. 2003 Jun;22(6):1281-7
references: 12785585
references: Biochim Biophys Acta. 1998 Nov 27;1425(3):527-33
references: 9838216
references: Appl Environ Microbiol. 2005 Feb;71(2):629-35
references: 15691911
references: Toxicol Appl Pharmacol. 2005 Mar 15;203(3):264-72
references: 15737680
references: Mol Microbiol. 1997 Nov;26(4):779-87
references: 9427407
references: Comp Biochem Physiol B Biochem Mol Biol. 2004 Mar;137(3):287-96
references: 15050516
references: J Chem Ecol. 2004 Mar;30(3):483-500
references: 15139303
references: Mol Ecol Resour. 2012 Nov;12(6):1048-57
references: 22925691
references: Science. 2011 Feb 4;331(6017):555-61
references: 21292972
references: Sci Total Environ. 2011 Mar 1;409(7):1351-6
references: 21239047
references: Genome. 2005 Aug;48(4):606-9
references: 16094427
references: Oecologia. 2005 Jan;142(1):20-7
references: 15378347
references: Oecologia. 1994 Apr;97(3):333-341
references: 28313628
references: Environ Toxicol. 2005 Jun;20(3):314-22
references: 15892063
references: J Exp Biol. 2012 Jun 15;215(Pt 12):2051-9
references: 22623193
references: Oecologia. 1993 Oct;96(1):40-42
references: 28313751
references: Science. 2008 Apr 4;320(5872):57-8
references: 18388279
references: Appl Environ Microbiol. 2001 Aug;67(8):3523-9
references: 11472928
references: Proc Biol Sci. 2003 Jun 7;270(1520):1209-14
references: 12816661
references: Sci Am. 1994 Jan;270(1):78-86
references: 8284661
references: Evolution. 2001 Nov 11;55(11):2203-14
references: 11794781
references: Aquat Toxicol. 2011 Aug;104(3-4):230-42
references: 21635866