Diffusible gas transmitter signaling in the copepod crustacean Calanus finmarchicus: Identification of the biosynthetic enzymes of nitric oxide (NO), carbon monoxide (CO) and hydrogen sulfide (H2S) using a de novo assembled transcriptome

Abstract

Neurochemical signaling is a major component of physiological/behavioral control throughout the animal kingdom. Gas transmitters are perhaps the most ancient class of molecules used by nervous systems for chemical communication. Three gases are generally recognized as being produced by neurons: nitric oxide (NO), carbon monoxide (CO) and hydrogen sulfide (H2S). As part of an ongoing effort to identify and characterize the neurochemical signaling systems of the copepod Calanus finmarchicus, the biomass dominant zooplankton in much of the North Atlantic Ocean, we have mined a de novo assembled transcriptome for sequences encoding the neuronal biosynthetic enzymes of these gases, i.e. nitric oxide synthase (NOS), heme oxygenase (HO) and cystathionine β-synthase (CBS), respectively. Using Drosophila proteins as queries, two NOS-, one HO-, and one CBS-encoding transcripts were identified. Reverse BLAST and structural analyses of the deduced proteins suggest that each is a true member of its respective enzyme family. RNA-Seq data collected from embryos, early nauplii, late nauplii, early copepodites, late copepodites and adults revealed the expression of each transcript to be stage specific: one NOS restricted primarily to the embryo and the other was absent in the embryo but expressed in all other stages, no CBS expression in the embryo, but present in all other stages, and HO expressed across all developmental stages. Given the importance of gas transmitters in the regulatory control of a number of physiological processes, these data open opportunities for investigating the roles these proteins play under different life-stage and environmental conditions in this ecologically important species.

Glutathione S-Transferase (GST) Gene Diversity in the Crustacean Calanus finmarchicus – Contributors to Cellular Detoxification

“…finmarchicus transcripts [ 34 ]. This estimate was confirmed by other studies that used the transcriptome to characterize neural signaling molecules in this crustacean [ 35 – 38 ]. Here, this transcriptome was mined for putative GST-encoding transcripts.…”

Identification and molecular characterization of nitric oxide synthase (NOS) gene in the intertidal copepod Tigriopus japonicus

“…Thus, T. japonicus would maintain the NOS mRNA level at early development in response to immune challenge or environmental stressors. In C. finmarchicus, similar transcript abundance was observed (Christie et al, 2014). The expression of one of two NOS isoforms, Calfi-NOSII (annotated as an inducible form of NOS) was significantly higher in nauplii and copepodites than in adults, suggesting that NOS is induced in response to direct exposure to pathogens after hatching (Christie et al, 2014).…”

“…The deduced amino acid sequence of the T. japonicus NOS protein was compared with those of representative invertebrate NOSs and vertebrate iNOSs, showing that T. japonicus NOS gene is a member of the NO gene family due to high similarity in the NOS domains. Among small crustaceans, lineage-specific NOS evolution was observed, as the copepod C. finmarchicus (Calanoida; Calanidae) and the waterflea Daphnia (Diplostraca; Daphniidae) have two NOS isoforms (Labbé et al, 2009;Christie et al, 2014), while T. japonicus has a single NOS gene yet as we tried to find additional NOS gene and its conserved oxygenase and reductase domains on T. japonicus genome and transcriptome database. In general, vertebrate iNOS lacks an autoinhibitory loop, and thus it must be stimulated at the transcriptional level by an environmental or immune challenge (Griffith and Stuehr, 1995;Bogdan, 2001).…”

“…The inhibitory loop is also observed in the amino acid sequence of D. magna NOS1 ( 585 H-N 655 ; ACQ55299). Both NOS1 and NOS2 genes of C. finmarchicus and D. magna were differentially regulated during life cycle or immune challenge (Labbé et al, 2009;Christie et al, 2014). Thus, gene duplication with subfunctionalization or gene loss events would be highlighted in the crustacean NOS family.…”

Modulation of growth cone filopodial length by carbon monoxide

“…Its endogenous production primarily occurs through the degradation of heme by the enzyme heme oxygenase (HO), which has two main isoforms: (1) an inducible form (HO‐1) found throughout the body that is activated by cellular stress and injury and (2) a constitutively active form (HO‐2) found primarily in the nervous system and testes. While studies of CO within the mature nervous system have led to its description as an effector of circadian rhythms (Artinian et al, ), nociception (Steiner et al, ; Carvalho et al, ), learning and memory (Cutajar and Edwards, ), and olfaction (Zufall and Leinders‐Zufall, ), the presence of both HO isoforms throughout development in both vertebrates and invertebrates (Maines, ; Shi et al, ; Knipp and Bicker, ; Christie et al, ) suggests that CO may also play an important role as a developmental signaling molecule; however, unlike another endogenously produced gas, nitric oxide (NO), little is known about the role CO plays in neuronal development and regeneration.…”