-Omic Analysis of the Sepia officinalis White Body: New Insights into Multifunctionality and Haematopoiesis Regulation

Abstract

Cephalopods, like other Protostomes, lack an adaptive immune system and only rely on an innate immune system. The main immune cells are haemocytes, able to respond to pathogens and external attacks. First reports based on morphological observations suggested that the white body located in the optic sinuses of cuttlefish was at the origin of haemocytes. Combining transcriptomic and proteomic analyses, we identified several factors known to be involved in haematopoiesis in Vertebrate species in cuttlefish white body. Among these factors, members of the JAK-STAT signalling pathway were identified, some of them for the first time in a molluscan transcriptome and proteome. Immune factors such as members of the Toll/NF-κB signalling pathway, pattern recognition proteins and receptors, and members of the oxidative stress responses were also identified, and support an immune role of the white body. Both transcriptome and proteome analyses revealed that the white body harbours an intense metabolism concurrent with the haematopoietic function. Finally, a comparative analysis of the white body and haemocyte proteomes revealed many proteins in common, confirming previous morphological studies on the origin of haemocytes in cuttlefish. This molecular work demonstrates that the white body is multifunctional and provides bases for haematopoiesis regulation in cuttlefish.

In-Depth In Silico Search for Cuttlefish (Sepia officinalis) Antimicrobial Peptides Following Bacterial Challenge of Haemocytes

“…Based on the presence of a blastx hit against the Uniprot-Swissprot database, 15% and 14% of all transcripts included in the c-hct and Vs-hct transcriptomes, respectively, were annotated. These low levels of annotation are striking but commonly observed in such an atypical model, as already reported for the white body (WB) with 20% [41], the central nervous system (CNS) with 28% [42], the accessory nidamental gland (ANG) with 34%, or the posterior salivatory gland (PSG) with 45% [43]. Besides, in another cephalopod species (Octopus vulgaris), 18.95% of the hct transcriptome was annotated [44].…”

“…They were up-regulated in Argopecten irradians after exposure to peptidoglycans [59] and in Chlamys farreri after exposure to V. anguillarum and Micrococcus lysodeikticus [60]. So-BPI/LBP, previously identified in cuttlefish WB [41], shares 52.58% sequence identity with E. scolopes LBP-3 (AEL03862.1) and 30% sequence identity with C. gigas LBP/BPI (AAN84552.1), whose recombinant protein possesses antibacterial activity against Escherichia coli strains [61]. Finally, partial sequence of So-Gal-2 previously identified in cuttlefish WB [41], which shares 46% sequence identity with galectin-2-2 (AJA37869.1) identified in the Littorina littorea hct transcriptome [62] was identified in cuttlefish hct.…”

“…So-BPI/LBP, previously identified in cuttlefish WB [41], shares 52.58% sequence identity with E. scolopes LBP-3 (AEL03862.1) and 30% sequence identity with C. gigas LBP/BPI (AAN84552.1), whose recombinant protein possesses antibacterial activity against Escherichia coli strains [61]. Finally, partial sequence of So-Gal-2 previously identified in cuttlefish WB [41], which shares 46% sequence identity with galectin-2-2 (AJA37869.1) identified in the Littorina littorea hct transcriptome [62] was identified in cuttlefish hct. TPM values showed that all these immune-related factors seemed up-regulated with fold change greater than 1.10 ( Table 1).…”

“…anguillarum and Micrococcus lysodeikticus [ 60 ]. So -BPI/LBP, previously identified in cuttlefish WB [ 41 ], shares 52.58% sequence identity with E . scolopes LBP-3 (AEL03862.1) and 30% sequence identity with C .…”