Blood Samples Stabilized in the Field for Laboratory Analyses after 24 Hours

The goal of this study was to examine the optimal storage and handling conditions of blood from Gulf Coast fish for analyses of biomarker data (cell viability by membrane integrity and nuclear DNA fragmentation). Properly designed laboratory studies can substantiate conclusions that complement field studies. Robust generation of data from field-collected samples requires that they be well-maintained before analysis. Live cells are preferable for studying a variety of endpoints, but time in shipment can necessitate the inclusion of a fixative to prevent degradation.  In this study, channel catfish (Ictalurus punctatus) blood samples stored at 24°C and 4°C were compared using a commercial, non-toxic, human-cell stabilizing solution (Streck), 4% paraformaldehyde (fixative), or acid citrate dextrose (ACD) anticoagulant.  Catfish blood was diluted to 3, 2 or 1 parts blood to one part stabilizer.  For each dilution, cell viability and nuclear fragmentation were negatively correlated.  For the 3:1 dilution, viability was over 80% and fragmentation less than 10%.  Over the course of 14 days, data were not correlated with time for days 0 – 4 (repeated measures analysis of variance; n = 5).  The cell stabilizer was equivalent to paraformaldehyde at preventing DNA fragmentation.  For cells stored with paraformaldehyde, nuclear DNA fragmentation was higher at 24ºC than at 4 ºC (P = 0.0002); however, for cells stored in the stabilizer, no fragmentation differences were noted between temperatures.  At 4ºC, the sample in ACD showed higher levels of DNA fragmentation than either the cell stabilizer or the fixative (P = 0.0047).  Overall, the results support the use of the cell stabilizing solution for maintaining catfish blood in good condition in order to obtain objective cellular and molecular data.  The stabilizer is currently being used in collections of samples from gulf sturgeon (Acipenser oxyrhynchus) and could be considered for use with other taxa.