Comparative Analysis of the Soluble Proteome and the Cytolytic Activity of Unbleached and Bleached Millepora complanata (“Fire Coral”) from the Mexican Caribbean

Abstract

Coral bleaching caused by global warming has resulted in massive damage to coral reefs worldwide. Studies addressing the consequences of elevated temperature have focused on organisms of the class Anthozoa, and up to now, there is little information regarding the mechanisms by which reef forming Hydrozoans face thermal stress. In this study, we carried out a comparative analysis of the soluble proteome and the cytolytic activity of unbleached and bleached Millepora complanata (“fire coral”) that inhabited reef colonies exposed to the 2015–2016 El Niño-Southern Oscillation in the Mexican Caribbean. A differential proteomic response involving proteins implicated in key cellular processes, such as glycolysis, DNA repair, stress response, calcium homeostasis, exocytosis, and cytoskeleton organization was found in bleached hydrocorals. Four of the proteins, whose levels increased in bleached specimens, displayed sequence similarity to a phospholipase A2, an astacin-like metalloprotease, and two pore forming toxins. However, a protein, which displayed sequence similarity to a calcium-independent phospholipase A2, showed lower levels in bleached cnidarians. Accordingly, the hemolytic effect of the soluble proteome of bleached hydrocorals was significantly higher, whereas the phospholipase A2 activity was significantly reduced. Our results suggest that bleached M. complanata is capable of increasing its toxins production in order to balance the lack of nutrients supplied by its symbionts.

Marine Natural Products from the Yucatan Peninsula

“…Out of the 66 marine natural products identified, 26 correspond to structures that were not previously reported. These 26 new chemical entities correspond to three aliphatic polyketides (1-3), one glycolipid (7), two diterpenes (15,16), two steroids (24,25), one triterpenoid saponin (40), and 17 conotoxins (49)(50)(51)(52)(53)(54)(55)(56)(57)(58)(59)(60)(61)(62)(63)(64)(65). Figure 15 displays the overall biogenetic distribution of the reported compounds.…”

“…From specimens of Conus spurius, collected in Isla Arena, Campeche state, were isolated and identified by reverse transcription polymerase chain reaction, seven conotoxins. Four of them belong to the T-1 conotoxin family, (18V) sr5a (59), (18T) sr5a (60), "extended" (61), and "hydrophilic" (62), which were reported in 2009 [34], and they are very similar to the conotoxin sr5a (53). The other three, reported in 2010, were the known conotoxin sr11a (56) already reported in 2007 [31] and the new conotoxins, sr11b (63) and sr11c (64) [35] (Figure 9).…”

Implications of bleaching on cnidarian venom ecology

“…Despite the ecological importance of a fully functional venom delivery system, it is surprising how few studies have attempted to look at how bleaching may impact on the cnidae and/or venom of bleached photo-symbiotic cnidarians. Indeed, only six research papers within the literature have been found to meet the criteria of comparing the effects on bleaching on either the cnidom, venom profile or toxicity, either over time ( Hoepner et al, 2019 ), or as direct comparisons to an unbleached cohort ( García-Arredondo et al, 2011 ; Gundlach, 2018 ; Gundlach and Watson, 2019 ; Hernández-Elizárraga et al, 2019 ; Olguín-López et al, 2019 ).…”

“…Bleaching has been shown to not only impact on the cnidarian venom apparatus system, but to also compromise the ability of cnidarians to produce venom ( Hoepner et al, 2019 ), and also change the properties within the venom itself ( García-Arredondo et al, 2011 ; Hernández-Elizárraga et al, 2019 ; Hoepner et al, 2019 ). Bleaching resulted in the volume of lyophilized crude venom of E. quadricolor (Actiniaria), which was collected monthly over a period of five months, to reduce significantly with time ( Hoepner et al, 2019 ).…”

“…Bleaching has also been shown to have mixed effects on the overall protein concentration of cnidarian venom ( García-Arredondo et al, 2011 ; Hernández-Elizárraga et al, 2019 ; Hoepner et al, 2019 ; Olguín-López et al, 2019 ). Despite significant reductions in volume of crude venom that was collected from bleached sea anemones, the venom that was obtained nine weeks after the onset of the prolonged bleaching study, was shown to have a higher concentration of protein ( Hoepner et al, 2019 ).…”