Data from: Are Niemann-Pick type C proteins key players in cnidarian-dinoflagellate endosymbioses?

The symbiotic interaction between cnidarians, such as corals and sea anemones, and the unicellular algae Symbiodinium is regulated by yet poorly understood cellular mechanisms, despite the ecological importance of coral reefs. These mechanisms, including host-symbiont recognition and metabolic exchange, control symbiosis stability under normal conditions, but also lead to symbiosis breakdown (bleaching) during stress. This study describes the repertoire of the sterol-trafficking proteins Niemann-Pick type C (NPC1 and NPC2) in the symbiotic sea anemone Anemonia viridis. We found one NPC1 gene instead of two in vertebrates. While only one NPC2 gene is present in most metazoans, this gene has been duplicated in cnidarians and we detected four NPC2 genes in A. viridis. However, only one gene (AvNPC2-d) was upregulated in symbiotic sea anemones and displayed higher expression in the gastrodermis (symbiont-containing tissue) than in the epidermis. We performed immunolabeling experiments on tentacle cross sections and demonstrated that the AvNPC2-d protein was closely associated with symbiosomes. In addition, AvNPC1 and AvNPC2-d gene expression was strongly downregulated during stress, especially at the onset of symbiosis breakdown. These data suggest that AvNPC2-d is involved in both the stability and dysfunction of cnidarian-dinoflagellate symbioses

Differential distribution of lipids in epidermis, gastrodermis and hosted Symbiodinium in the sea anemone Anemonia viridis

International audienceCnidarian-dinoflagellate symbiosis mainly relies on nutrient recycling, thus providing both partners with a competitive advantage in nutrient-poor waters. Essential processes related to lipid metabolism can be influenced by various factors, including hyperthermal stress. This can affect the lipid content and distribution in both partners, while contributing to symbiosis disruption and bleaching. In order to gain further insight into the role and distribution of lipids in the cnidarian metabolism, we investigated the lipid composition of the sea anemone Anemonia viridis and its photosynthetic dinoflagellate endosymbionts (Symbiodinium). We compared the lipid content and fatty acid profiles of the host cellular layers, non-symbiotic epidermal and symbiont-containing gastrodermal cells, and those of Symbiodinium, in a mass spectrometry-based assessment. Lipids were more concentrated in Symbiodinium cells, and the lipid class distribution was dominated by polar lipids in all tissues. The fatty acid distribution between host cell layers and Symbiodinium cells suggested potential lipid transfers between the partners. The lipid composition and distribution was modified during short-term hyperthermal stress, mainly in Symbiodinium cells and gastrodermis. Exposure to elevated temperature rapidly caused a decrease in polar lipid C18 unsaturated fatty acids and a strong and rapid decrease in the abundance of polar lipid fatty acids relative to sterols. These lipid indicators could therefore be used as sensitive biomarkers to assess the physiology of symbiotic cnidarians, especially the effect of thermal stress at the onset of cnidarian bleaching. Overall, the findings of this study provide some insight on key lipids that may regulate maintenance of the symbiotic interaction

TreeFile_NPC1_Figure2

Tree data generated using the maximum likelihood method and the PhyML3.0 software. Compute these data with the SeaView program to display the NPC1 phylogenetic tree

TreeFile_NPC2_Figure1

Tree data generated using the maximum likelihood method and the PhyML3.0 software. Compute these data with the SeaView program to display the NPC2 phylogenetic tree

PrimersEfficiency

PCR efficiency of primers used in this study (DNA quantification and heat stress experiment

qPCR_QuantifZxAv

Symbiodinium quantification by real-time quantitative PCR measurement of the relative nuclear gene copy number (symbiont to host nuclei) during hyperthermal stress

Alignment file of NPC1 protein sequences_Figure2

Sequences of NPC1 proteins aligned using the MAFFT program. This alignment was used to generate a phylogenetic tree using the phyML 3.0 sofware, the maximum likelihood method and the LG+I+G substitution model (I=0.1 and gamma factor=1.266). Accession numbers: HsNPC1L1, NP_001095118.1; BtNPC1L1, XP_588051; DrNPC1L1, XP_002663230.2; CiNPC1-b, XP_002122922; DmNPC1-a, NP_609357; DmNPC1-b, NP_608417; HsNPC1, AAK25791.1; BtNPC1, AAI51277; DrNPC1, XP_001919958.3; CiNPC1-a, XP_002120129; SpNPC1, XP_780036; AvNPC1, HG670297; NvNPC1, XM_001634881.1; AdNPC1, adi_v1.19271 from ADIG_G-PEP_111201 database; HmNPC1, XM_002164383.1; AqNPC1, XP_003384854.1

Normalizationfactor_HeatStress

Normalization factor was calculated based on the expression level of RCC2 and COP-ɣ genes using the GeNorm software, for the heat stress experiment

qPCR_HeatStress

Relative gene expression data analysis (raw Ct and normalized expression data) for the heat stress experimen

Alignment file of NPC2 protein sequences_Figure1A

Sequences of NPC2 proteins aligned using the MAFFT program. This alignment was used to construct a phylogenetic tree using the maximum likelihood method (phyML3.0 software) and the WAG+I+G substitution model (I=0.057 and gamma factor=5.831). Accession number of sequences: AvNPC2-d,HG670301; AvNPC2-c, HG670300; NvNPC2-2, XP_001627355; NvNPC2-3, XP_001635502; AdNPC2-2, adi_v1.06781; AdNPC2-3, adi_v1.23434; AdNPC2-4, adi_v1.10342; AvNPC2-b, HG670299; AdNPC2-1, adi_v1.14987 + contig adi_v1.08570; AdNPC2-5, aug_v2a.08569; AdNPC2-6, aug_v2a.08570; AvNPC2-a, HG670298; NvNPC2-1, XP_001622874; HsNPC2, NP_006423.1; DrNPC2-a, NP_001122191.1; DrNPC2-b, NP_775331.1; CiNPC2-1, XP_002127695.1; TaNPC2, XP_002109765.1; HvNPC2-3, XP_002166396.2; Hv NPC2-4, XP_002166374.2; Hv NPC2-2, XP_002164043.1; Hv NPC2-1, XP_002156875.1; AqNPC2, CL5422Contig1 from AQUE_CAP3_100104 assembly from compage