Mucus transcriptome differs among lakes
Following exposure to crude oil, Greer et al.(2019) demonstrated that
sequencing of mahi-mahi mucus was effectively able to distinguish
transcriptomes of oil-exposed and non-exposed individuals. Our results
from the present study expand the utility of mucus as a nonlethal
sampling tool by demonstrating that sequencing of RNA in mucus can
distinguish transcriptomic differences among geographically-distinct
populations (Figure 2). In terms of transcriptomic similarity,
individuals from L224 and L373 were most similar whereas individuals
from L260 and L223 clustered apart from all other lakes (Figure 2). It
should be noted that the lakes of interest in the present study are
located in close proximity to one another and within the same ecozone
and, thus, vary only slightly in terms of ecological conditions. Even
so, unique transcriptome profiles by lake were captured within lake
trout mucus indicating that sequencing of mucus is able to robustly
capture gene expression changes among fish populations. Therefore,
analysis of mucus may be a viable tool for ecological studies interested
in assessing gene expression differences among fish populations. As
mucus sampling is nonlethal and minimally-invasive, this method could be
especially useful for assessing threatened and endangered populations
without inducing further perturbations. Moreover, differential gene
expression analysis and subsequent gene ontology analysis can be used to
further elucidate transcriptomic relationships among populations and
identify abiotic and biotic factors driving population differences.