Proteomic measurement
Proteomic profiles were determined for all 752 specimens. For small
copepods (< 2 mm) the whole specimen, for larger copepods
(such as Calanus spp., Metridia sp., Paraeuchaetaspp.) a piece of the cephalosome was shortly dried at room temperature
and kept in an Eppendorf tube. Depending on sample size 5-10 µl matrix
solution (α-Cyano-4-hydroxycinnamic acid as saturated solution in 50%
acetonitrile, 47.5% LC-MS grade water, and 2.5% trifluoroacetic acid)
was added. After at least 10 min extraction, 1.2 µl of each sample was
added onto the target plate, with 2-3 replicates. Protein mass spectra
were measured from 2 to 20 kDa using a linear-mode MALDI-TOF System
(Microflex LT/SH, Bruker Daltonics). Peak intensities were analyzed
during random measurement in the range between 2 and 20 kDa using a
centroid peak detection algorithm, a signal to noise threshold of 2 and
a minimum intensity threshold of 400 with a peak resolution higher than
400 for mass spectra evaluation. Proteins/Oligonucleotide method was
employed for fuzzy control with a maximal resolution 10 times above the
threshold. For each sample 240 satisfactory shots were summed up.