Particle Size Distribution of Environmental DNA from the Nuclei of Marine Fish

Environmental
DNA (eDNA) analyses have enabled a more efficient
surveillance of species distribution and composition than conventional
methods. However, the characteristics and dynamics of eDNA (e.g.,
origin, state, transport, and fate) remain unknown. This is especially
limited for the eDNA derived from nuclei (nu-eDNA), which has recently
been used in eDNA analyses. Here, we compared the particle size distribution
(PSD) of nu-eDNA from Japanese Jack Mackerel (Trachurus japonicus) with that of mt-eDNA (eDNA derived from mitochondria) reported
in previous studies. We repeatedly sampled rearing water from the
tanks under multiple temperatures and fish biomass levels, and quantified
the copy numbers of size-fractioned nu-eDNA. We found that the concentration
of nu-eDNA was higher than that of mt-eDNA at 3–10 μm
size fraction. Moreover, at the 0.8–3 μm and 0.4–0.8
μm size fractions, eDNA concentrations of both types increased
with higher temperature and their degradation tended to be suppressed.
These results imply that the production of eDNA from large to small
size fractions could buffer the degradation of small-sized eDNA, which
could improve its persistence in water. Our findings will contribute
to refine the difference between nu- and mt-eDNA properties, and assist
eDNA analyses as an efficient tool for the conservation of aquatic
species.