Effects of environmental factors on C-type lectin recognition to zooxanthellae in the stony coral Pocillopora damicornis

Cnidarian Pattern Recognition Receptor Repertoires Reflect Both Phylogeny and Life History Traits

“…The ability of cnidarian lectins to interact with MASP and activate the lectin-complement pathway has yet to be investigated. Both of the cnidarian lectins for which we have functional studies and the majority of cnidarian species in this study lack CTLs with the collagen helix domain characteristic of MBL ( 11 , 116 ). However, it is possible that cnidarians are capable of lectin-complement activation despite lacking collagen domains as studies have shown that CTLs lacking collagen domains are still able to interact with MASP ( 119 , 120 ).…”

“…Based on their large and diverse CTL repertoires, cnidarians are likely utilizing CTLD containing proteins for a variety of functions. Transcriptomic and proteomic studies indicate that CTLs are involved in coral wound healing (121) and disease response (122,123) in addition to their hypothesized role in mediating symbiosis with Symbiodiniaceae (11,(116)(117)(118). Thus, further functional studies of cnidarian CTLs are warranted and should focus both on highly conserved CTLs and on novel cnidarian CTLs with the potential to shed light on disease processes.…”

“…The expansion of CTLs across all 15 cnidarian species relative to the sponge outgroup aligns with previous findings of diverse and large CTLD containing protein repertoires in invertebrate species ( 5 , 47 ). Despite this diversity and the potential for cnidarian CTLs to greatly contribute to immune specificity, functional studies have only been conducted on homologs of mannose binding lectin (MBL), the activator of the lectin complement pathway ( 11 , 116 ). These studies indicate that MBL homologs in two corals, P. damicornis ( 116 ) and A millepora ( 11 ) are capable of binding to both bacteria and Symbiodiniaceae leading to the hypothesis that lectin/glycan interactions are a mechanism of recognition during symbiont infection.…”

“…Despite this diversity and the potential for cnidarian CTLs to greatly contribute to immune specificity, functional studies have only been conducted on homologs of mannose binding lectin (MBL), the activator of the lectin complement pathway ( 11 , 116 ). These studies indicate that MBL homologs in two corals, P. damicornis ( 116 ) and A millepora ( 11 ) are capable of binding to both bacteria and Symbiodiniaceae leading to the hypothesis that lectin/glycan interactions are a mechanism of recognition during symbiont infection. This hypothesis has found some support from transcriptomic studies ( 117 , 118 ).…”

Increased Ammonium Assimilation Activity in the Scleractinian Coral Pocillopora damicornis but Not Its Symbiont After Acute Heat Stress

“…GS (BC0915, Solarbio, China), GDH (A125, JIANCHENG, China), and GOGAT (BC0070, Solarbio, China) kits were employed to determine their activities in the coral and symbiont supernatants according to manufacturer's protocol. After the total enzyme activities were obtained, the concentrations of total protein in the supernatants were quantified using bicinchoninic acid assay (BCA) method (Zhou et al, 2018) and used to normalize the measured activities of GS, GDH, and GOGAT to U mg −1 protein.…”