| The Hawaiian bobtail squid Euprymna scolopes forms a mutualistic symbiosis with the bacteria Vibrio fischeri. Among the diverse aspects regulating symbiosis, the immune system is thought to play an essential role in the establishment and maintenance of symbiosis. Therefore, the purpose of my study was to identify transcripts that could be involved in the host immune system and their relationship with the V. fischeri symbiosis. Different molecular tools, including transcriptome analysis and quantitative PCR, were used for this goal. Among the molecules identified was a C-type lectin. My studies showed that this lectin is involved in lipopolysaccharide recognition and capable of bacterial agglutination, suggesting a role as pattern recognition receptor. Additionally, 14 putative serine proteases were identified. Two of these proteases, Es-SP11 and Es-SP15, were studied more in depth and their expression patterns in the squid light organ were analyzed in presence and absence of symbionts. Es-SP11 expression results suggested that this transcript is involved in symbiosis, specifically during symbiont expulsion of the light organ. The pattern expression for Es-SP15 suggested that this transcript could be associated with the squid's circadian rhythm. However, further analyzes are required to understand its function in E. scolopes.;Finally, I did an analysis of a transcriptome from the white body tissue of the Southern dumpling squid Euprymna tasmanica. In cephalopods, the white body is considered to be an immune and hematopoietic organ mainly due to the fact that hemocytes are known to be present in high numbers and in different developmental stages. However, to our knowledge, there were no studies showing any molecular evidence of such functions. Transcriptomic analysis showed that several hematopoiesis transcripts 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-&kgr;beta, and MAPK pathways were also found, as well as other immune transcripts 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. |
