MEPS 671:67-79 (2021)  -  DOI: https://doi.org/10.3354/meps13749

ABSTRACT: Diatom aggregates can play an important role in the formation of marine oil snow and the transport of oil from the sea surface to the benthos, yet their molecular response to oil has not been characterized. Here we use RNA-seq to analyze the transcriptome-wide responses of aggregates of the common Gulf of Mexico diatom Odontella aurita exposed to the water accommodated fraction of 2 different types of oil, Macondo surrogate and Refugio Beach oil. We identify a common set of 353 genes that are differentially expressed in response to both Macondo and Refugio oil exposure, relative to controls. Genes related to photosynthesis, and nuclear and ribosomal processes were all down-regulated in oil treatments, while genes related to repairing membrane damage, cellular stress, and the production of exopolymeric substances were up-regulated. Differential expression of genes was often greater in magnitude in the Refugio than the Macondo oil treatment, which may be due to differences in oil concentration in the treatments or to the physiochemical characteristics of the oils. Exposure to Refugio oil induced more severe nucleolar stress and more damage to chloroplasts than the lighter Macondo oil, which triggered an up-regulation of a more diverse suite of stress-response genes.

KEY WORDS: Diatoms · Marine oil snow · Transcriptome · Macondo surrogate oil · Refugio Beach oil