Ka. Hobson et al., PRESERVATION OF BLOOD AND TISSUE SAMPLES FOR STABLE-CARBON AND STABLE-NITROGEN ISOTOPE ANALYSIS, Canadian journal of zoology, 75(10), 1997, pp. 1720-1723
Researchers engaged in collecting animal material for stable-carbon an
d stable-nitrogen isotope analysis are frequently faced with the need
to preserve tissues prior to transportation to the laboratory. In many
cases, freezing is not possible in the field, so we investigated the
potential of several techniques for preserving tissues for this purpos
e. We also included preservation techniques used for DNA analyses in o
rder to evaluate how they might alter delta(13)C and delta(15)N values
in tissues and, ultimately, whether archived DNA samples could be use
d for stable-isotope assay. Tissues included blood and pectoral muscle
from quail (Coturnix coturnix japonica) and blood from sheep (Ovis ar
ies). Preservation techniques for blood included freeze-drying (contro
l), drying on precombusted glass-fibre filter paper, and storing in 70
% ethanol, 10% buffered formalin, ABI lysis buffer, and Queen's lysis
buffer. After 8 weeks, the use of both lysis buffers and formalin resu
lted in significant depletion of C-13 and N-15 in blood. Values for sa
mples dried on glass-fibre filter paper or stored in 70% ethanol did n
ot differ significantly from those for the control. Muscle tissue was
freeze-dried (control) or stored in 70% ethanol, 10% buffered formalin
, or DMSO solution. Both the DMSO and formalin treatments resulted in
significant depletion of C-13 and N-15 compared with the control. Only
the 70% ethanol treatment did not result in changes to either isotope
ratio in muscle. Where freezing is not possible, we recommend that bl
ood samples be dried or stored in 70% ethanol. Our study provides an e
stimate of isotopic correction factors that may be applied to tissues
archived for DNA analysis or stored in formalin.