Abstract
Sea lamprey (SL; Petromyzon marinus), one of the oldest living vertebrates, have a complex metamorphic life cycle. Following hatching, SL transition into a microphagous, sediment burrowing larval stage, and after 2–10+ years, the larvae undergo a dramatic metamorphosis, transforming into parasitic juveniles that feed on blood and bodily fluids of fishes; adult lamprey cease feeding, spawn, and die. Since gut microbiota are critical for the overall health of all animals, we examined the microbiota associated with SLs in each life history stage. We show that there were significant differences in the gut bacterial communities associated with the larval, parasitic juvenile, and adult life stages. The transition from larval to the parasitic juvenile stage was marked with a significant shift in bacterial community structure and reduction in alpha diversity. The most abundant SL-associated phyla were Proteobacteria, Fusobacteria, Bacteroidetes, Verrucomicrobia, Actinobacteria, and Firmicutes, with their relative abundances varying among the stages. Moreover, while larval SL were enriched with unclassified Fusobacteriaceae, unclassified Verrucomicrobiales and Cetobacterium, members of the genera with fastidious nutritional requirements, such as Streptococcus, Haemophilus, Cutibacterium, Veillonella, and Massilia, were three to four orders of magnitude greater in juveniles than in larvae. In contrast, adult SLs were enriched with Aeromonas, Iodobacter, Shewanella, and Flavobacterium. Collectively, our findings show that bacterial communities in the SL gut are dramatically different among its life stages. Understanding how these communities change over time within and among SL life stages may shed more light on the role that these gut microbes play in host growth and fitness.
Highlights
Lampreys (Petromyzontiformes) are one of the oldest living groups of vertebrates (Docker et al, 2015)
The gut bacterial communities associated with sea lamprey (SL) larval, parasitic juvenile, and adult life stages differed significantly (ANOSIM R = 0.881; p-value = 0.001)
Larval SLs were enriched for Fusobacteriaceae, unclassified Verrucomicrobiales, unclassified Bacteroidales, unclassified Micrococcales, Rhodocyclaceae, and Rubritaleaceae, whereas Streptococcaceae was enriched in parasitic SLs, and Aeromonadaceae, Chitinibacteraceae, and Shewanellaceae in the adult SLs (Figure 4)
Summary
Lampreys (Petromyzontiformes) are one of the oldest living groups of vertebrates (Docker et al, 2015). Lampreys number over 40 species and comprise the agnathan (jawless) vertebrates (Potter et al, 2015) with a lineage dating back 500 million years (Janvier, 2007). The lamprey species Petromyzon marinus, often generically referred to as the sea lamprey (SL), have a complex metamorphic life cycle. Sea Lamprey Gut Microbiota (filter-feeding-like) larval stage that burrow in soft sediment in or near streams. After several years (ranging 2–17) (Dawson et al, 2015), the larvae undergo a dramatic metamorphosis (Manzon et al, 2015), transform into juveniles that increase markedly in size, reaching 30–110 cm, and parasitize fishes in lakes or oceans, primarily feeding on their blood (Potter et al, 2015). Parasitic lampreys return to streams where they cease feeding, spawn, and die to complete the life cycle (Johnson et al, 2015)
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