Skip to main content
SpringerLink
Log in

In silico analyses suggest the cardiac ganglion of the lobster, Homarus americanus, contains a diverse array of putative innexin/innexin-like proteins, including both known and novel members of this protein family

  • Short Communication
  • Published:
Invertebrate Neuroscience

Abstract

Gap junctions are physical channels that connect adjacent cells, permitting the flow of small molecules/ions between the cytoplasms of the coupled units. Innexin/innexin-like proteins are responsible for the formation of invertebrate gap junctions. Within the nervous system, gap junctions often function as electrical synapses, providing a means for coordinating activity among electrically coupled neurons. While some gap junctions allow the bidirectional flow of small molecules/ions between coupled cells, others permit flow in one direction only or preferentially. The complement of innexins present in a gap junction determines its specific properties. Thus, understanding innexin diversity is key for understanding the full potential of electrical coupling in a species/system. The decapod crustacean cardiac ganglion (CG), which controls cardiac muscle contractions, is a simple pattern-generating neural network with extensive electrical coupling among its circuit elements. In the lobster, Homarus americanus, prior work suggested that the adult neuronal innexin complement consists of six innexins (Homam-Inx1-4 and Homam-Inx6-7). Here, using a H. americanus CG-specific transcriptome, we explored innexin complement in this portion of the lobster nervous system. With the exception of Homam-Inx4, all of the previously described innexins appear to be expressed in the H. americanus CG. In addition, transcripts encoding seven novel putative innexins (Homam-Inx8-14) were identified, four (Homam-Inx8-11) having multiple splice variants, e.g., six for Homam-Inx8. Collectively, these data indicate that the innexin complement of the lobster nervous system in general, and the CG specifically, is likely significantly greater than previously reported, suggesting the possibility of expanded gap junction diversity and function in H. americanus.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2
Fig. 3
Fig. 4

References

  • Alcamí P, Pereda AE (2019) Beyond plasticity: the dynamic impact of electrical synapses on neural circuits. Nat Rev Neurosci 20:253–271

    Article  Google Scholar 

  • Beyer EC, Berthoud VM (2018) Gap junction gene and protein families: connexins, innexins, and pannexins. Biochim Biophys Acta Biomembr 1860:5–8

    Article  CAS  Google Scholar 

  • Calabrese RL, Norris BJ, Wenning A (2016) The neural control of heartbeat in invertebrates. Curr Opin Neurobiol 41:68–77

    Article  CAS  Google Scholar 

  • Christie AE, Chi M, Lameyer TJ, Pascual MG, Shea DN, Stanhope ME, Schulz DJ, Dickinson PS (2015) Neuropeptidergic signaling in the American lobster Homarus americanus: new insights from high-throughput nucleotide sequencing. PLoS One 10:e0145964

    Article  Google Scholar 

  • Christie AE, Roncalli V, Cieslak MC, Pascual MG, Yu A, Lameyer TJ, Stanhope ME, Dickinson PS (2017) Prediction of a neuropeptidome for the eyestalk ganglia of the lobster Homarus americanus using a tissue-specific de novo assembled transcriptome. Gen Comp Endocrinol 243:96–119

    Article  CAS  Google Scholar 

  • Christie AE, Yu A, Roncalli V, Pascual MG, Cieslak MC, Warner AN, Lameyer TJ, Stanhope ME, Dickinson PS, Hull JJ (2018a) Molecular evidence for an intrinsic circadian pacemaker in the cardiac ganglion of the American lobster, Homarus americanus—is diel cycling of heartbeat frequency controlled by a peripheral clock system? Mar Genom 41:19–30

    Article  Google Scholar 

  • Christie AE, Yu A, Pascual MG, Roncalli V, Cieslak MC, Warner AN, Lameyer TJ, Stanhope ME, Dickinson PS, Hull JJ (2018b) Circadian signaling in Homarus americanus: region-specific de novo assembled transcriptomes show that both the brain and eyestalk ganglia possess the molecular components of a putative clock system. Mar Genom 40:25–44

    Article  Google Scholar 

  • Christie AE, Stanhope ME, Gandler HI, Lameyer TJ, Pascual MG, Shea DN, Yu A, Dickinson PS, Hull JJ (2018c) Molecular characterization of putative neuropeptide, amine, diffusible gas and small molecule transmitter biosynthetic enzymes in the eyestalk ganglia of the American lobster, Homarus americanus. Invertebr Neurosci 18:12

    Article  Google Scholar 

  • Cooke IM (2002) Reliable, responsive pacemaking and pattern generation with minimal cell numbers: the crustacean cardiac ganglion. Biol Bull 202:108–136

    Article  Google Scholar 

  • Dickinson PS, Qu X, Stanhope ME (2016) Neuropeptide modulation of pattern-generating systems in crustaceans: comparative studies and approaches. Curr Opin Neurobiol 41:149–157

    Article  CAS  Google Scholar 

  • Dickinson PS, Hull JJ, Miller A, Oleisky ER, Christie AE (2019) To what extent may peptide receptor gene diversity/complement contribute to functional flexibility in a simple pattern-generating neural network? Comp Biochem Physiol Part D Genom Proteom 30:262–282

    CAS  Google Scholar 

  • Edgar RC (2004) MUSCLE: multiple sequence alignment with high accuracy and high throughput. Nucleic Acids Res 32:1792–1797

    Article  CAS  Google Scholar 

  • Harris AL (2018) Electrical coupling and its channels. J Gen Physiol 150:1606–1639

    Article  Google Scholar 

  • Hooper SL, DiCaprio RA (2004) Crustacean motor pattern generator networks. Neurosignals 13:50–69

    Article  CAS  Google Scholar 

  • Jones DT, Taylor WR, Thornton JM (1992) The rapid generation of mutation data matrices from protein sequences. Comput Appl Biosci 8:275–282

    CAS  PubMed  Google Scholar 

  • Kandarian B, Sethi J, Wu A, Baker M, Yazdani N, Kym E, Sanchez A, Edsall L, Gaasterland T, Macagno E (2012) The medicinal leech genome encodes 21 innexin genes: different combinations are expressed by identified central neurons. Dev Genes Evol 222:29–44

    Article  CAS  Google Scholar 

  • Katoh K, Standley DM (2013) MAFFT multiple sequence alignment software version 7: improvements in performance and usability. Mol Biol Evol 30:772–780

    Article  CAS  Google Scholar 

  • Kearse M, Moir R, Wilson A, Stones-Havas S, Cheung M, Sturrock S, Buxton S, Cooper A, Markowitz S, Duran C, Thierer T, Ashton B, Meintjes P, Drummond A (2012) Geneious Basic: an integrated and extendable desktop software platform for the organization and analysis of sequence data. Bioinformatics 28:1647–1649

    Article  Google Scholar 

  • Kumar S, Stecher G, Li M, Knyaz C, Tamura K (2018) MEGA X: molecular evolutionary genetics analysis across computing platforms. Mol Biol Evol 35:1547–1549

    Article  CAS  Google Scholar 

  • Lane BJ, Kick DR, Wilson DK, Nair SS, Schulz DJ (2018) Dopamine maintains network synchrony via direct modulation of gap junctions in the crustacean cardiac ganglion. Elife 7:e39368

    Article  Google Scholar 

  • Le SQ, Gascuel O (2008) An improved general amino acid replacement matrix. Mol Biol Evol 25:1307–1320

    Article  CAS  Google Scholar 

  • Letunic I, Bork P (2018) 20 years of the SMART protein domain annotation resource. Nucleic Acids Res 46:D493–D496

    Article  CAS  Google Scholar 

  • Northcutt AJ, Lett KM, Garcia VB, Diester CM, Lane BJ, Marder E, Schulz DJ (2016) Deep sequencing of transcriptomes from the nervous systems of two decapod crustaceans to characterize genes important for neural circuit function and modulation. BMC Genom 17:868

    Article  Google Scholar 

  • O’Brien J (2019) Design principles of electrical synaptic plasticity. Neurosci Lett 695:4–11

    Article  Google Scholar 

  • Otopalik AG, Lane B, Schulz DJ, Marder E (2019) Innexin expression in electrically coupled motor circuits. Neurosci Lett 695:19–24

    Article  CAS  Google Scholar 

  • Pereda AE, Macagno E (2017) Electrical transmission: two structures, same functions? Dev Neurobiol 77:517–521

    Article  Google Scholar 

  • Pereda AE, Curti S, Hoge G, Cachope R, Flores CE, Rash JE (2013) Gap junction-mediated electrical transmission: regulatory mechanisms and plasticity. Biochim Biophys Acta 1828:134–146

    Article  CAS  Google Scholar 

  • Phelan P (2005) Innexins: members of an evolutionarily conserved family of gap-junction proteins. Biochim Biophys Acta 1711:225–245

    Article  CAS  Google Scholar 

  • Phelan P, Goulding LA, Tam JL, Allen MJ, Dawber RJ, Davies JA, Bacon JP (2008) Molecular mechanism of rectification at identified electrical synapses in the Drosophila giant fiber system. Curr Biol 18:1955–1960

    Article  CAS  Google Scholar 

  • Rzhetsky A, Nei M (1992) A simple method for estimating and testing minimum evolution trees. Mol Biol Evol 9:945–967

    CAS  Google Scholar 

  • Saitou N, Nei M (1987) The neighbor-joining method: a new method for reconstructing phylogenetic trees. Mol Biol Evol 4:406–425

    CAS  Google Scholar 

  • Schulz DJ, Lane BJ (2017) Homeostatic plasticity of excitability in crustacean central pattern generator networks. Curr Opin Neurobiol 43:7–14

    Article  CAS  Google Scholar 

  • Shruti S, Schulz DJ, Lett KM, Marder E (2014) Electrical coupling and innexin expression in the stomatogastric ganglion of the crab Cancer borealis. J Neurophysiol 112:2946–2958

    Article  CAS  Google Scholar 

  • Starich T, Sheehan M, Jadrich J, Shaw J (2001) Innexins in C. elegans. Cell Commun Adhes 8:311–314

    Article  CAS  Google Scholar 

  • Stebbings LA, Todman MG, Phillips R, Greer CE, Tam J, Phelan P, Jacobs K, Bacon JP, Davies JA (2002) Gap junctions in Drosophila: developmental expression of the entire innexin gene family. Mech Dev 113:197–205

    Article  CAS  Google Scholar 

  • Thurmond J, Goodman JL, Strelets VB, Attrill H, Gramates LS, Marygold SJ, Matthews BB, Millburn G, Antonazzo G, Trovisco V, Kaufman TC, Calvi BR, FlyBase Consortium (2019) FlyBase 2.0: the next generation. Nucleic Acids Res 47:D759–D765

    Article  CAS  Google Scholar 

  • Willecke K, Eiberger J, Degen J, Eckardt D, Romualdi A, Güldenagel M, Deutsch U, Söhl G (2002) Structural and functional diversity of connexin genes in the mouse and human genome. Biol Chem 383:725–737

    Article  CAS  Google Scholar 

Download references

Acknowledgements

Lisa Baldwin and Dr. Colin Brent are thanked for reading and commenting on earlier versions of this article. This work was supported by funds from the National Science Foundation (IOS-1353023 and IOS-1856307 [to AEC]; IOS-1354567 and IOS-1856433 [to PSD]), the National Institutes of Health (INBRE grant 8P20GM103423-12), the Cades Foundation (to AEC), and base CRIS funding from the US Department of Agriculture (Project #2020-22620-022-00D; to JJH). Mention of trade names or commercial products in this article is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the USDA; the USDA is an equal opportunity provider and employer.

Author information

Authors and Affiliations

  1. Békésy Laboratory of Neurobiology, Pacific Biosciences Research Center, School of Ocean and Earth Science and Technology, University of Hawaii at Manoa, 1993 East-West Road, Honolulu, HI, 96822, USA

    Andrew E. Christie

  2. Pest Management and Biocontrol Research Unit, US Arid Land Agricultural Research Center, USDA Agricultural Research Services, Maricopa, AZ, 85138, USA

    J. Joe Hull

  3. Department of Biology, Bowdoin College, 6500 College Station, Brunswick, ME, 04011, USA

    Patsy S. Dickinson

Authors
  1. Andrew E. Christie
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. J. Joe Hull
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Patsy S. Dickinson
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Andrew E. Christie.

Ethics declarations

Conflict of interest

None.

Additional information

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Electronic supplementary material

Below is the link to the electronic supplementary material.

Supplemental Figure 1

Deduced amino acid sequences of putative innexin proteins likely present in the cardiac ganglion of Homarus americanus (longest sequences shown). In this figure, membrane-spanning domains identified by the online program SMART are highlighted in black, with innexin signature motifs (–YYQWV–) shown in red font, and variants on this motif (–FYRWI–) shown in pink font. Amino acids in innexin proteins shown in gray were identified from sources other than the cardiac ganglion (see “Filling in sequence gaps using other lobster datasets” section for specifics). (DOCX 164 kb)

Supplementary material 2 (DOCX 80 kb)

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Christie, A.E., Hull, J.J. & Dickinson, P.S. In silico analyses suggest the cardiac ganglion of the lobster, Homarus americanus, contains a diverse array of putative innexin/innexin-like proteins, including both known and novel members of this protein family. Invert Neurosci 20, 5 (2020). https://doi.org/10.1007/s10158-020-0238-6

Download citation

  • Received:

  • Accepted:

  • Published:

  • DOI: https://doi.org/10.1007/s10158-020-0238-6

Keywords

Search

Navigation