The immune response of cephalopods from head to foot.

Cephalopods are a diverse group of marine molluscs that have proven their worth in a vast array of ways, ranging from their importance within ecological settings and increasing commercial value, to their recent use as model organisms in biological research. However, despite their acknowledged importance, our understanding of basic cephalopod biology does not equate their ecological, societal, and scientific significance. Among these undeveloped research areas, cephalopod immunology stands out because it encompasses a wide variety of scientific fields including many within the biological and chemical sciences, and because of its potential biomedical and commercial relevance. This review aims to address the current knowledge on the topic of cephalopod immunity, focusing on components and functions already established as part of the animals' internal defense mechanisms, as well as identifying gaps that would benefit from future research. More specifically, the present review details both cellular and humoral defenses, and organizes them into sensor, signaling, and effector components. Molluscan, and particularly cephalopod immunology has lagged behind many other areas of study, but thanks to the efforts of many dedicated researchers and the assistance of modern technology, this gap is steadily decreasing. A better understanding of cephalopod immunity will have a positive impact on the health and survival of one of the most intriguing and unique animal groups on the planet, and will certainly influence many other areas of human interest such as ecology, evolution, physiology, symbiosis, and aquaculture.

Transcriptome analysis of the white body of the squid Euprymna tasmanica with emphasis on immune and hematopoietic gene discovery.

In the mutualistic relationship between the squid Euprymna tasmanica and the bioluminescent bacterium Vibrio fischeri, several host factors, including immune-related proteins, are known to interact and respond specifically and exclusively to the presence of the symbiont. In squid and octopus, the white body is considered to be an immune organ mainly due to the fact that blood cells, or hemocytes, are known to be present in high numbers and in different developmental stages. Hence, the white body has been described as the site of hematopoiesis in cephalopods. However, to our knowledge, there are no studies showing any molecular evidence of such functions. In this study, we performed a transcriptomic analysis of white body tissue of the Southern dumpling squid, E. tasmanica. Our primary goal was to gain insights into the functions of this tissue and to test for the presence of gene transcripts associated with hematopoietic and immune processes. Several hematopoiesis genes including CPSF1, GATA 2, TFIID, and FGFR2 were found to be expressed in the white body. In addition, transcripts associated with immune-related signal transduction pathways, such as the toll-like receptor/NF-κß, and MAPK pathways were also found, as well as other immune genes previously identified in E. tasmanica's sister species, E. scolopes. This study is the first to analyze an immune organ within cephalopods, and to provide gene expression data supporting the white body as a hematopoietic tissue.

Identification, molecular characterization, and gene expression analysis of a CD109 molecule in the Hawaiian bobtail squid Euprymna scolopes.

All organisms have unique immune systems that help them identify and eliminate invading microorganisms. A group of evolutionary ancient molecules, the thioester-containing proteins (TEP) superfamily, are known to play an important immune role by aiding animal hosts in the recognition, destruction, and elimination of hazardous microorganisms and their products. Our laboratory focuses on studying the role of the immune system in the mutualistic relationship between the sepiolid squid, Euprymna scolopes and its bioluminescent symbiont Vibrio fischeri. In the present study, we report the identification of a novel TEP-like transcript expressed in the light organ of squid. Characterization of the full-length coding sequence showed a molecule of 4218 nucleotides, corresponding to 1406 amino acids. Further sequence analysis revealed it contained structural characteristics of A2M molecules, including the thioester and receptor-binding domains. Analysis using the predicted amino acid sequence suggested this transcript was a homologue of CD109 molecules, thus we named it E. scolopes-CD109 (Es-CD109). In addition to the light organ, we were able to detect and amplify Es-CD109 in 12 out of 14 adult squid tissues tested. Quantification experiments showed that Es-CD109 expression levels were significantly lower in the light organ of symbiotic compared to aposymbiotic juveniles, suggesting a possible down-regulation of the host immune response in the presence of the bacterial symbiont.