The Caspase Homologues in Scallop Chlamys farreri and Their Expression Responses to Toxic Dinoflagellates Exposure

Abstract

The cysteine aspartic acid-specific protease (caspase) family is distributed across vertebrates and invertebrates, and its members are involved in apoptosis and response to cellular stress. The Zhikong scallop (Chlamys farreri) is a bivalve mollusc that is well adapted to complex marine environments, yet the diversity of caspase homologues and their expression patterns in the Zhikong scallop remain largely unknown. Here, we identified 30 caspase homologues in the genome of the Zhikong scallop and analysed their expression dynamics during all developmental stages and following exposure to paralytic shellfish toxins (PSTs). The 30 caspase homologues were classified as initiators (caspases-2/9 and caspases-8/10) or executioners (caspases-3/6/7 and caspases-3/6/7-like) and displayed increased copy numbers compared to those in vertebrates. Almost all of the caspase-2/9 genes were highly expressed throughout all developmental stages from zygote to juvenile, and their expression in the digestive gland and kidney was slightly influenced by PSTs. The caspase-8/10 genes were highly expressed in the digestive gland and kidney, while PSTs inhibited their expression in these two organs. After exposure to different Alexandrium PST-producing algae (AM-1 and ACDH), the number of significantly up-regulated caspase homologues in the digestive gland increased with the toxicity level of PST derivatives, which might be due to the higher toxicity of GTXs produced by AM-1 compared to the N-sulphocarbamoyl analogues produced by ACDH. However, the effect of these two PST-producing algae strains on caspase expression in the kidney seemed to be stronger, possibly because the PST derivatives were transformed into highly toxic compounds in scallop kidney, and suggested an organ-dependent response to PSTs. These results indicate the dedicated control of caspase gene expression and highlight their contribution to PSTs in C. farreri. This work provides a further understanding of the role of caspase homologues in the Zhikong scallop and can guide future studies focussing on the role of caspases and their interactions with PSTs.

Expansion and diversity of caspases in Mytilus coruscus contribute to larval metamorphosis and environmental adaptation

“…In total, 47 caspase genes were identified from the genome of M. coruscus . This number is in line with the previous report among 40 caspase genes in C. gigas [ 6 ], and 30 genes in C. farreri [ 7 ]. An expansion event of caspase genes was observed in the genome of M. coruscus , which was consistent with that observed in other bivalves [ 6 , 7 ].…”

“…This number is in line with the previous report among 40 caspase genes in C. gigas [ 6 ], and 30 genes in C. farreri [ 7 ]. An expansion event of caspase genes was observed in the genome of M. coruscus , which was consistent with that observed in other bivalves [ 6 , 7 ]. The mammalian caspases are subclassified into four types, namely, initiators, executioners, inflammatory caspase, and keratinocyte differentiation-related caspase.…”

“…However, only seven and four caspase genes are retained in Drosophila melanogaster and Caenorhabditis elegans due to lineage-specific losses [ 5 ]. In mollusks, 40 caspase genes have been reported in the Crassostrea gigas [ 6 ], 30 have been identified in the Chlamys farreri [ 7 ], and 3 initiator and 4 executioner caspases also were characterized in the mussel Mytilus galloprovincialis [ 8 , 9 ]. The structure and function show differences among the caspase family members.…”

“…In mollusks, several caspases are involved in apoptotic processes associated with developmental processes [ 6 , 31 ], responses to pathogen infection [ 23 , 32 , 33 ], and environmental stressors [ 32 , 34 , 35 ]. Systematic characterization and functional analysis of caspases have also been reported in other bivalves, such as oyster C. gigas [ 6 ] and scallop C. farreri [ 7 ], mussels M. galloprovincialis [ 8 , 9 ] and M. edulis [ 36 ]. Interestingly, compared with vertebrates, caspase family genes are significantly expanded in oysters and scallops, which may help them adapt to complex living environments.…”

Solvent-driven biotoxin into nano-units as a versatile and sensitive SERS strategy

“…Accidental ingestion of shellfish containing this toxin can lead to neurotoxicity and, in severe cases, death due to respiratory muscle paralysis. 4,5 Hepatotoxins include microcysin (MC), nodularin (NOD) and others. MC cause liver and kidney damage by inhibiting the activity of protein phosphatases 1 and 2A.…”