@article {gallant2011signal, title = {Signal variation and its morphological correlates in Paramormyrops kingsleyae provide insight into the evolution of electrogenic signal diversity in mormyrid electric fish}, journal = {Journal of Comparative Physiology A}, volume = {197}, year = {2011}, pages = {799{\textendash}817}, publisher = {Springer-Verlag}, abstract = {

We describe patterns of geographic variation in electric signal waveforms among populations of the mormyrid electric fish species Paramormyrops kingsleyae. This analysis includes study of electric organs and electric organ discharge (EOD) signals from 553 specimens collected from 12 localities in Gabon, West-Central Africa from 1998 to 2009. We measured time, slope, and voltage values from nine defined EOD \“landmarks\” and determined peak spectral frequencies from each waveform; these data were subjected to principal components analysis. The majority of variation in EODs is explained by two factors: the first related to EOD duration, the second related to the magnitude of the weak head-negative pre-potential, P0. Both factors varied clinally across Gabon. EODs are shorter in eastern Gabon and longer in western Gabon. Peak P0 is slightly larger in northern Gabon and smaller in southern Gabon. P0 in the EOD is due to the presence of penetrating-stalked (Pa) electrocytes in the electric organ while absence is due to the presence of non-penetrating stalked electrocytes (NPp). Across Gabon, the majority of P. kingsleyae populations surveyed have only individuals with P0-present EODs and Pa electrocytes. We discovered two geographically distinct populations, isolated from others by barriers to migration, where all individuals have P0-absent EODs with NPp electrocytes. At two sites along a boundary between P0-absent and P0-present populations, P0-absent and P0-present individuals were found in sympatry; specimens collected there had electric organs of intermediate morphology. This pattern of geographic variation in EODs is considered in the context of current phylogenetic work. Multiple independent paedomorphic losses of penetrating stalked electrocytes have occurred within five Paramormyrops species and seven genera of mormyrids. We suggest that this key anatomical feature in EOD signal evolution may be under a simple mechanism of genetic control, and may be easily influenced by selection or drift throughout the evolutionary history of mormyrids.

}, doi = {10.1007/s00359-011-0643-8}, url = {https://doi.org/10.1007/s00359-011-0643-8}, author = {Jason R. Gallant and Matthew E Arnegard and John P Sullivan and Bruce A Carlson and Carl D Hopkins} } @article {gallant2014genomic, title = {Genomic basis for the convergent evolution of electric organs}, journal = {Science}, volume = {344}, number = {6191}, year = {2014}, pages = {1522{\textendash}1525}, publisher = {American Association for the Advancement of Science}, abstract = {

Little is known about the genetic basis of convergent traits that originate repeatedly over broad taxonomic scales. The myogenic electric organ has evolved six times in fishes to produce electric fields used in communication, navigation, predation, or defense. We have examined the genomic basis of the convergent anatomical and physiological origins of these organs by assembling the genome of the electric eel (Electrophorus electricus) and sequencing electric organ and skeletal muscle transcriptomes from three lineages that have independently evolved electric organs. Our results indicate that, despite millions of years of evolution and large differences in the morphology of electric organ cells, independent lineages have leveraged similar transcription factors and developmental and cellular pathways in the evolution of electric organs.

}, doi = {10.1126/science.1254432}, url = {https://www.science.org/doi/10.1126/science.1254432}, author = {Jason R. Gallant and Traeger, Lindsay L and Volkening, Jeremy D and Moffett, Howell and Chen, Po-Hao and Novina, Carl D and Phillips Jr, George N and Anand, Rene and Wells, Gregg B and Pinch, Matthew and others} } @article {pitchers2016electric, title = {Electric fish genomics: progress, prospects, and new tools for neuroethology}, journal = {Journal of Physiology-Paris}, volume = {110}, number = {3}, year = {2016}, pages = {259{\textendash}272}, publisher = {Elsevier}, abstract = {

Electric fish have served as a model system in biology since the 18th century, providing deep insight into the nature of bioelectrogenesis, the molecular structure of the synapse, and brain circuitry underlying complex behavior. Neuroethologists have collected extensive phenotypic data that span biological levels of analysis from molecules to ecosystems. This phenotypic data, together with genomic resources obtained over the past decades, have motivated new and exciting hypotheses that position the weakly electric fish model to address fundamental 21st century biological questions. This review article considers the molecular data collected for weakly electric fish over the past three decades, and the insights that data of this nature has motivated. For readers relatively new to molecular genetics techniques, we also provide a table of terminology aimed at clarifying the numerous acronyms and techniques that accompany this field. Next, we pose a research agenda for expanding genomic resources for electric fish research over the next 10 years. We conclude by considering some of the exciting research prospects for neuroethology that electric fish genomics may offer over the coming decades, if the electric fish community is successful in these endeavors.

}, doi = {10.1016/j.jphysparis.2016.10.003}, url = {https://doi.org/10.1016/j.jphysparis.2016.10.003}, author = {Pitchers, William R and Savvas J. Constantinou and Losilla, Mauricio and Jason R. Gallant} } @article {swapna2018electrostatic, title = {Electrostatic tuning of a potassium channel in electric fish}, journal = {Current Biology}, volume = {28}, number = {13}, year = {2018}, pages = {2094{\textendash}2102}, publisher = {Elsevier}, abstract = {

Molecular variation contributes to the evolution of adaptive phenotypes, though it is often difficult to understand precisely how. The adaptively significant electric organ discharge behavior of weakly electric fish is the direct result of biophysical membrane properties set by ion channels. Here, we describe a voltage-gated potassium-channel gene in African electric fishes that is under positive selection and highly expressed in the electric organ. The channel produced by this gene shortens electric organ action potentials by activating quickly and at hyperpolarized membrane potentials. The source of these properties is a derived patch of negatively charged amino acids in an extracellular loop near the voltage sensor. We demonstrate that this negative patch acts by contributing to the global surface charge rather than by local interactions with specific amino acids in the channel\&$\#$39;s extracellular face. We suggest a more widespread role for this loop in the evolutionary tuning of voltage-dependent channels.

}, doi = {10.1016/j.cub.2018.05.012}, url = {https://www.sciencedirect.com/science/article/pii/S0960982218306146}, author = {Swapna, Immani and Ghezzi, Alfredo and York, Julia M and Markham, Michael R and Halling, D Brent and Lu, Ying and Jason R. Gallant and Zakon, Harold H} } @article {647, title = {A review of the reproductive biology of mormyroid~fishes: An emerging model for biomedical research}, journal = {Journal of Experimental Zoology Part B: Molecular and Developmental EvolutionJournal of Experimental Zoology Part B: Molecular and Developmental EvolutionJ Exp Zool B Mol Dev Evol}, volume = {342}, year = {2024}, month = {2024/05/01}, pages = {144 - 163}, publisher = {John Wiley \& Sons, Ltd}, abstract = {Abstract Mormyroidea is a superfamily of weakly electric African fishes with great potential as a model in a variety of biomedical research areas including systems neuroscience, muscle cell and craniofacial development, ion channel biophysics, and flagellar/ciliary biology. However, they are currently difficult to breed in the laboratory setting, which is essential for any tractable model organism. As such, there is a need to better understand the reproductive biology of mormyroids to breed them more reliably in the laboratory to effectively use them as a biomedical research model. This review seeks to (1)~briefly highlight the biomedically relevant phenotypes of mormyroids and (2) compile information about mormyroid reproduction including sex differences, breeding season, sexual maturity, gonads, gametes, and courtship/spawning behaviors. We also highlight areas of mormyroid reproductive biology that are currently unexplored and/or have the potential for further investigation that may provide insights into more successful mormyroid laboratory breeding methods.}, keywords = {biomedicine, electric fish, mormyrid, reproduction, teleost}, isbn = {1552-5007}, url = {https://doi.org/10.1002/jez.b.23242}, author = {Saunders, Alyssa N. and Jason R. Gallant} } @article {539, title = {Electric Fish Genomics: Progress, Prospects, and New Tools for Neuroethology}, journal = {Journal of Physiology-Paris}, year = {2016}, month = {Jan-10-2016}, abstract = {

Electric fish have served as a model system in biology since the 18th century, providing deep insight into the nature of bioelectrogenesis, the molecular structure of the synapse, and brain circuitry underlying complex behavior. Neuroethologists have collected extensive phenotypic data that span biological levels of analysis from molecules to ecosystems. This phenotypic data, together with genomic resources obtained over the past decades, have motivated new and exciting hypotheses that position the weakly electric fish model to address fundamental 21st century biological questions. This review article considers the molecular data collected for weakly electric fish over the past three decades, and the insights that data of this nature has motivated. For readers relatively new to molecular genetics techniques, we also provide a table of terminology aimed at clarifying the numerous acronyms and techniques that accompany this field. Next, we pose a research agenda for expanding genomic resources for electric fish research over the next 10 years. We conclude by considering some of the exciting research prospects for neuroethology that electric fish genomics may offer over the coming decades, if the electric fish community is successful in these endeavors.

}, keywords = {CRISPR, electric fish, genome editing, genomics, transcriptomics, transgenics}, issn = {09284257}, doi = {10.1016/j.jphysparis.2016.10.003}, url = {http://linkinghub.elsevier.com/retrieve/pii/S0928425716300079}, author = {Pitchers, William R. and Savvas J. Constantinou and Losilla, Mauricio and Jason R. Gallant} } @article {836, title = {Differential expression of genes and proteins between electric organ and skeletal muscle in the mormyrid electric fish Brienomyrus brachyistius}, journal = {Journal of Experimental Biology}, volume = {215}, year = {2012}, month = {07/2012}, pages = {2479 - 2494}, abstract = {

Electric organs (EOs) have evolved independently in vertebrates six times from skeletal muscle (SM). The transcriptional changes accompanying this developmental transformation are not presently well understood. Mormyrids and gymnotiforms are two highly convergent groups of weakly electric fish that have independently evolved EOs: while much is known about development and gene expression in gymnotiforms, very little is known about development and gene expression in mormyrids. This lack of data limits prospects for comparative work. We report here on the characterization of 28 differentially expressed genes between SM and EO tissues in the mormyrid Brienomyrus brachyistius, which were identified using suppressive subtractive hybridization (SSH). Forward and reverse SSH was performed on tissue samples of EO and SM resulting in one cDNA library enriched with mRNAs expressed in EO, and a second library representing mRNAs unique to SM. Nineteen expressed sequence tags (ESTs) were identified in EO and nine were identified in SM using BLAST searching of Danio rerio sequences available in NCBI databases. We confirmed differential expression of all 28 ESTs using RT-PCR. In EO, these ESTs represent four classes of proteins: (1) ion pumps, including the - and -subunits of Na+/K+-ATPase, and a plasma membrane Ca2+-ATPase; (2) Ca2+-binding protein S100, several parvalbumin paralogs, calcyclin-binding protein and neurogranin; (3) sarcomeric proteins troponin I, myosin heavy chain and actin-related protein complex subunit 3 (Arcp3); and (4) the transcription factors enhancer of rudimentary homolog (ERH) and myocyte enhancer factor 2A (MEF2A). Immunohistochemistry and western blotting were used to demonstrate the translation of seven proteins (myosin heavy chain, Na+/K+-ATPase, plasma membrane Ca2+-ATPase, MEF2, troponin and parvalbumin) and their cellular localization in EO and SM. Our findings suggest that mormyrids express several paralogs of muscle-specific genes and the proteins they encode in EOs, unlike gymnotiforms, which may post-transcriptionally repress several sarcomeric proteins. In spite of the similarity in the physiology and function of EOs in mormyrids and gymnotiforms, this study indicates that the mechanisms of development in the two groups may be considerably different.

}, issn = {1477-9145}, doi = {10.1242/jeb.063222}, author = {Jason R. Gallant and Carl D Hopkins and Deitcher, D. L.} } @article {853, title = {Differential expression of genes and proteins between electric organ and skeletal muscle in the mormyrid electric fish Brienomyrus brachyistius}, journal = {Journal of Experimental Biology}, volume = {215}, year = {2012}, month = {07/2012}, pages = {2479 - 2494}, abstract = {

Electric organs (EOs) have evolved independently in vertebrates six times from skeletal muscle (SM). The transcriptional changes accompanying this developmental transformation are not presently well understood. Mormyrids and gymnotiforms are two highly convergent groups of weakly electric fish that have independently evolved EOs: while much is known about development and gene expression in gymnotiforms, very little is known about development and gene expression in mormyrids. This lack of data limits prospects for comparative work. We report here on the characterization of 28 differentially expressed genes between SM and EO tissues in the mormyrid Brienomyrus brachyistius, which were identified using suppressive subtractive hybridization (SSH). Forward and reverse SSH was performed on tissue samples of EO and SM resulting in one cDNA library enriched with mRNAs expressed in EO, and a second library representing mRNAs unique to SM. Nineteen expressed sequence tags (ESTs) were identified in EO and nine were identified in SM using BLAST searching of Danio rerio sequences available in NCBI databases. We confirmed differential expression of all 28 ESTs using RT-PCR. In EO, these ESTs represent four classes of proteins: (1) ion pumps, including the \α- and \β-subunits of Na(+)/K(+)-ATPase, and a plasma membrane Ca(2+)-ATPase; (2) Ca(2+)-binding protein S100, several parvalbumin paralogs, calcyclin-binding protein and neurogranin; (3) sarcomeric proteins troponin I, myosin heavy chain and actin-related protein complex subunit 3 (Arcp3); and (4) the transcription factors enhancer of rudimentary homolog (ERH) and myocyte enhancer factor 2A (MEF2A). Immunohistochemistry and western blotting were used to demonstrate the translation of seven proteins (myosin heavy chain, Na(+)/K(+)-ATPase, plasma membrane Ca(2+)-ATPase, MEF2, troponin and parvalbumin) and their cellular localization in EO and SM. Our findings suggest that mormyrids express several paralogs of muscle-specific genes and the proteins they encode in EOs, unlike gymnotiforms, which may post-transcriptionally repress several sarcomeric proteins. In spite of the similarity in the physiology and function of EOs in mormyrids and gymnotiforms, this study indicates that the mechanisms of development in the two groups may be considerably different.

}, issn = {1477-9145}, doi = {10.1242/jeb.063222}, author = {Jason R. Gallant and Carl D Hopkins and Deitcher, D. L.} } @article {854, title = {From Sequence to Spike to Spark: Evo-devo-neuroethology of Electric Communication in Mormyrid Fishes}, journal = {Journal of Neurogenetics}, volume = {27}, year = {2013}, month = {09/2013}, pages = {106 - 129}, abstract = {

Mormyrid fishes communicate using pulses of electricity, conveying information about their identity, behavioral state, and location. They have long been used as neuroethological model systems because they are uniquely suited to identifying cellular mechanisms for behavior. They are also remarkably diverse, and they have recently emerged as a model system for studying how communication systems may influence the process of speciation. These two lines of inquiry have now converged, generating insights into the neural basis of evolutionary change in behavior, as well as the influence of sensory and motor systems on behavioral diversification and speciation. Here, we review the mechanisms of electric signal generation, reception, and analysis and relate these to our current understanding of the evolution and development of electromotor and electrosensory systems. We highlight the enormous potential of mormyrids for studying evolutionary developmental mechanisms of behavioral diversification, and make the case for developing genomic and transcriptomic resources. A complete mormyrid genome sequence would enable studies that extend our understanding of mormyrid behavior to the molecular level by linking morphological and physiological mechanisms to their genetic basis. Applied in a comparative framework, genomic resources would facilitate analysis of evolutionary processes underlying mormyrid diversification, reveal the genetic basis of species differences in behavior, and illuminate the origins of a novel vertebrate sensory and motor system. Genomic approaches to studying the evo-devo-neuroethology of mormyrid communication represent a deeply integrative approach to understanding the evolution, function, development, and mechanisms of behavior.

}, issn = {1563-5260}, doi = {10.3109/01677063.2013.799670}, url = {http://informahealthcare.com/doi/abs/10.3109/01677063.2013.799670}, author = {Bruce A Carlson and Jason R. Gallant} }