Metagenomic Insights Into the Structure and Function of Intestinal Microbiota of the Hadal Amphipods

Some macroalgae drift on the ocean and are stranded on coasts, and these stranded brown macroalgae are regarded to be degraded by organisms. Alginate is a major component of brown macroalgae. An uncovering of how carbon is cycled through brown macroalgae is needed to deeply understand coastal ecosystems. In this study, to gain insights into metabolism of brown macroalgae and alginate in the organisms, we initially confirmed that supralittoral talitrid amphipods (beach fleas or sandhoppers collected on the Shibagaki coast in Ishikawa Prefecture, Japan) fed on the brown macroalgae. We then isolated bacteria such as Vibrio sp. with alginate-assimilating capability from the gut of the amphipods. Metagenomic analysis of the gut of amphipods housed in several conditions (e.g. macroalgae or paper as feed, non-sterilized or sterilized environment) showed no condition-dependent compositions of bacteria and fungi, but Vibrio sp. were detected at high frequency, in good agreement with the isolation of Vibrio sp. An intervention study using antibiotics showed that amphipods fed on algae or paper at about the same rate in the presence or absence of antibiotics, and that the antibiotics had no effects on the life span. Moreover, intervention with antibiotics completely killed Vibrio sp. and some other bacteria, and had significant effects on the composition of the flora in the gut, with elimination of the variations observed in the guts of amphipods housed without antibiotics. These data suggest that microbes that were killed by antibiotics, including Vibrio sp., in the gut of talitrid amphipods are not essential for assimilation of brown macroalgae.

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“…accord with that detected in hadal amphipods [28]. The genus Thioclava was only found at high frequency in the stranded brown macroalgae.…”

Section: Plos Onesupporting

confidence: 83%

Bacterial and fungal gut microbiota of supralittoral talitrid amphipods feeding on brown macroalgae and paper

et al. 2022

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“…During an expedition of the New Britain Trench (8,824 m, 7.02◦S, 149.16◦E) in the West Pacific Ocean conducted in 2016, our group collected 10 A. gigantea individuals with attached eggs with a full ocean depth lander vehicle launched from the “Zhang Jian” research vessel that were immediately stored at −80 °C immediately. Detailed information about the lander vehicle and sampling process is described by Chan et al (2020 ; 2022 ; 2021) and Li et al (2021) . The specimens were stored in bubble chamber full of dry ice and delivered to Shanghai Ocean University.…”

Section: Methodsmentioning

confidence: 99%

“…In 2018, a tiny brood of hatching Alicella gigantea (Crustacea, Amphipoda, Lysianassoidea) was collected from the New Britain Trench (7.02S, 149.16E) at a depth of 8,824 m with the use of an autonomous deep-ocean lander. Detailed information about this lander vehicle and the sample collection process is described by Chan et al (2020 ; 2022 ; 2021) . To the best of our knowledge, this was the first collection of A. gigantea eggs from a hadal zone.…”

Section: Introductionmentioning

confidence: 99%

Morphological and molecular evolution of hadal amphipod’s eggs provides insights into embryogenesis under high hydrostatic pressure

Wang²,

Jiang³

et al. 2022

Front. Cell Dev. Biol.

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Hadal zones are unique habitats characterized by high hydrostatic pressure (HHP) and scarce food supplies. The ability of eggs of species dwelling in hadal zones to develop into normal embryo under high hydrostatic pressure is an important evolutionary and developmental trait. However, the mechanisms underlying the development of eggs of hadal-dwelling species remain unknown due to the difficulty of sampling ovigerous females. Here, morphological and transcriptome analyses of eggs of the “supergiant” amphipod Alicella gigantea collected from the New Britain Trench were conducted. The morphology of A. gigantea eggs, including size, was assessed and the ultrastructure of the eggshell was investigated by scanning electron microscopy. Transcriptome sequencing and molecular adaptive evolution analysis of A. gigantea eggs showed that, as compared with shallow-water Gammarus species, genes exhibiting accelerated evolution and the positively selected genes were mostly related to pathways associated with “mitosis” and “chitin-based embryonic cuticle biosynthetic process”, suggesting that “normal mitosis maintenance” and “cuticle development and protection” are the two main adaptation strategies for survival of eggs in hadal environments. In addition, the concentration of trimethylamine oxide (TMAO), an important osmotic regulator, was significantly higher in the eggs of hadal amphipods as compared to those of shallow-water species, which might promote the eggs’ adaptation abilities. Morphological identification, evolutionary analysis, and the trimethylamine oxide concentration of A. gigantea eggs will facilitate a comprehensive overview of the piezophilic adaptation of embryos in hadal environments and provide a strategy to analyze embryogenesis under high hydrostatic pressure.

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“…Two amphipod species, A. gigantea and B. schellenbergi, were collected from the New Britain Trench (8,824 m, 7.02 • S 149.16 • E) and Marceau Trench (6,690 m, 1.42 • N 148.74 • E) in the West Pacific Ocean (Figure 1). The autonomous deep-ocean lander vehicle, equipped with two cage traps baited with a suitable amount of mackerels, was launched from the "Zhang Jian" research vessel and deployed to the sea floor for up to 10 h. Detailed information about the lander vehicle and sampling was described in Chan et al (2020Chan et al ( , 2021. Upon the recovery of the lander, amphipods were preserved immediately at −80 • C until processed for analysis.…”

Section: Sample Collectionmentioning

confidence: 99%

The Adaptive Evolution and Gigantism Mechanisms of the Hadal “Supergiant” Amphipod Alicella gigantea

Wang

Jiang

et al. 2021

Front. Mar. Sci.

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Hadal trenches are commonly referred to as the deepest areas in the ocean and are characterized by extreme environmental conditions such as high hydrostatic pressures and very limited food supplies. Amphipods are considered the dominant scavengers in the hadal food web. Alicella gigantea is the largest hadal amphipod and, as such, has attracted a lot of attention. However, the adaptive evolution and gigantism mechanisms of the hadal “supergiant” remain unknown. In this study, the whole-body transcriptome analysis was conducted regarding the two hadal amphipods, one being the largest sized species A. gigantea from the New Britain Trench and another the small-sized species Bathycallisoma schellenbergi from the Marceau Trench. The size and weight measurement of the two hadal amphipods revealed that the growth of A. gigantea was comparatively much faster than that of B. schellenbergi. Phylogenetic analyses showed that A. gigantea and B. schellenbergi were clustered into a Lysianassoidea clade, and were distinct from the Gammaroidea consisting of shallow-water Gammarus species. Codon substitution analyses revealed that “response to starvation,” “glycerolipid metabolism,” and “meiosis” pathways were enriched among the positively selected genes (PSGs) of the two hadal amphipods, suggesting that hadal amphipods are subjected to intense food shortage and the pathways are the main adaptation strategies to survive in the hadal environment. To elucidate the mechanisms underlying the gigantism of A. gigantea, small-sized amphipods were used as the background for evolutionary analysis, we found the seven PSGs that were ultimately related to growth and proliferation. In addition, the evolutionary rate of the gene ontology (GO) term “growth regulation” was significantly higher in A. gigantea than in small-sized amphipods. By combining, those points might be the possible gigantism mechanisms of the hadal “supergiant” A. gigantea.

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Metagenomic Insights Into the Structure and Function of Intestinal Microbiota of the Hadal Amphipods

Cited by 13 publications

References 92 publications

Bacterial and fungal gut microbiota of supralittoral talitrid amphipods feeding on brown macroalgae and paper

Bacterial and fungal gut microbiota of supralittoral talitrid amphipods feeding on brown macroalgae and paper

Morphological and molecular evolution of hadal amphipod’s eggs provides insights into embryogenesis under high hydrostatic pressure

The Adaptive Evolution and Gigantism Mechanisms of the Hadal “Supergiant” Amphipod Alicella gigantea

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