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Lehotzky D, Zupanc GKH. Supervised learning algorithm for analysis of communication signals in the weakly electric fish Apteronotus leptorhynchus. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2024; 210:443-458. [PMID: 37704754 PMCID: PMC11106210 DOI: 10.1007/s00359-023-01664-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Revised: 07/22/2023] [Accepted: 07/25/2023] [Indexed: 09/15/2023]
Abstract
Signal analysis plays a preeminent role in neuroethological research. Traditionally, signal identification has been based on pre-defined signal (sub-)types, thus being subject to the investigator's bias. To address this deficiency, we have developed a supervised learning algorithm for the detection of subtypes of chirps-frequency/amplitude modulations of the electric organ discharge that are generated predominantly during electric interactions of individuals of the weakly electric fish Apteronotus leptorhynchus. This machine learning paradigm can learn, from a 'ground truth' data set, a function that assigns proper outputs (here: time instances of chirps and associated chirp types) to inputs (here: time-series frequency and amplitude data). By employing this artificial intelligence approach, we have validated previous classifications of chirps into different types and shown that further differentiation into subtypes is possible. This demonstration of its superiority compared to traditional methods might serve as proof-of-principle of the suitability of the supervised machine learning paradigm for a broad range of signals to be analyzed in neuroethology.
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Affiliation(s)
- Dávid Lehotzky
- Laboratory of Neurobiology, Department of Biology, Northeastern University, 360 Huntington Ave, Boston, MA, 02115, USA
| | - Günther K H Zupanc
- Laboratory of Neurobiology, Department of Biology, Northeastern University, 360 Huntington Ave, Boston, MA, 02115, USA.
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2
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The effect of urethane and MS-222 anesthesia on the electric organ discharge of the weakly electric fish Apteronotus leptorhynchus. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2023; 209:437-457. [PMID: 36799986 DOI: 10.1007/s00359-022-01606-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 12/16/2022] [Accepted: 12/20/2022] [Indexed: 02/18/2023]
Abstract
Urethane and MS-222 are agents widely employed for general anesthesia, yet, besides inducing a state of unconsciousness, little is known about their neurophysiological effects. To investigate these effects, we developed an in vivo assay using the electric organ discharge (EOD) of the weakly electric fish Apteronotus leptorhynchus as a proxy for the neural output of the pacemaker nucleus. The oscillatory neural activity of this brainstem nucleus drives the fish's EOD in a one-to-one fashion. Anesthesia induced by urethane or MS-222 resulted in pronounced decreases of the EOD frequency, which lasted for up to 3 h. In addition, each of the two agents caused a manifold increase in the generation of transient modulations of the EOD known as chirps. The reduction in EOD frequency can be explained by the modulatory effect of urethane on neurotransmission, and by the blocking of voltage-gated sodium channels by MS-222, both within the circuitry controlling the neural oscillations of the pacemaker nucleus. The present study demonstrates a marked effect of urethane and MS-222 on neural activity within the central nervous system and on the associated animal's behavior. This calls for caution when conducting neurophysiological experiments under general anesthesia and interpreting their results.
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Kennedy EKC, Janz DM. Can scale cortisol concentration be quantified non-lethally in wild fish species? CONSERVATION PHYSIOLOGY 2023; 11:coac081. [PMID: 36694596 PMCID: PMC9868526 DOI: 10.1093/conphys/coac081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 11/17/2022] [Accepted: 01/18/2023] [Indexed: 06/17/2023]
Abstract
Cortisol, the primary glucocorticoid in fishes, is secreted into the bloodstream in response to stress. Circulating cortisol accumulates in scales, a durable calcified structure that can be easily sampled from many fish species. As such, the use of scale cortisol concentration (SCC) is currently being explored as a means of chronic stress biomonitoring in wild fishes. Scales serve an important role in fish physiology and thus the number of scales required for reliable cortisol analysis is a limiting factor in the non-lethal collection of such samples. To date, scale cortisol quantification has also only been performed non-lethally in captive fishes and due to differences in stress responsiveness SCCs likely differ in wild species. As such, this study aimed to (1) apply our fish scale processing and analysis protocol to wild fish species and (2) apply it to five north temperate fish species to provide information useful to future non-lethal scale sampling regimes. Cortisol was successfully measured in scales collected from wild northern pike (Esox lucius), walleye (Sander vitreus), whitefish (Coregonus clupeaformis), white sucker (Catostomus commersonii) and captive rainbow trout (Oncorhynchus mykiss). SCCs were significantly different between species and thus the sample mass required for reliable cortisol analysis differed as well. In addition to the size of the fish and the mass of their scales this is an important consideration for future scale cortisol analyses as these factors could make SCC an attainable non-lethal sample matrix in some species of fish but impractical in others.
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Affiliation(s)
- Emily K C Kennedy
- Toxicology Undergraduate Program, University of Saskatchewan, 44 Campus Drive, Saskatoon, SK, S7K 5B3, Canada
| | - David M Janz
- Western College of Veterinary Medicine and Toxicology Centre, 52 Campus Drive, Saskatoon, SK, S7N 5B4, Canada
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Reproductive life-history strategies in a species-rich assemblage of Amazonian electric fishes. PLoS One 2019; 14:e0226095. [PMID: 31805125 PMCID: PMC6894849 DOI: 10.1371/journal.pone.0226095] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Accepted: 11/19/2019] [Indexed: 11/19/2022] Open
Abstract
The reproductive biology of only a small fraction of Neotropical freshwater fishes has been described, and detailed comparative studies of reproductive life-history variation in the Neotropical ichthyofauna are lacking. Here we describe interspecific variation in reproductive life history for a multi-species assemblage of the electric knifefish genus Brachyhypopomus (Hypopomidae: Gymnotiformes: Ostariophysi) from Amazonian floodplain and terra firme stream systems. During a year-round quantitative sampling program, we collected and measured key life-history traits from 3,410 individuals. Based on oocyte size distributions, and on circannual variation in gonadosomatic indices, hepatosomatic indices, and capture-per-unit-effort abundance of reproductive adults, we concluded that all species exhibit a single protracted annual breeding season during which females spawn fractionally. We found small clusters of post-larval individuals in one floodplain species and one terra firme stream species, but no signs of parental care. From analyses of body size-frequency distributions and otolith growth increments, we concluded that five species in our study area have approximately one-year (annual) semelparous life history with a single reproductive period followed by death, while two species have a two-year iteroparous life history, with breeding in both year-groups. Despite predictions from life-history theory we found no salient correlations between life history strategy (semelparity or iteroparity) and habitat occupancy (floodplain or terra firme stream). In the iteroparous species B. beebei, we documented evidence for reproductive restraint in the first breeding season relative to the second breeding season and argue that this is consistent with age-regulated terminal investment.
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Vitalo AG, Ilieş I, Zupanc GKH. Calbindin-D 28k expression in spinal electromotoneurons of the weakly electric fish Apteronotus leptorhynchus during adult development and regeneration. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2019; 205:595-608. [PMID: 31165281 DOI: 10.1007/s00359-019-01343-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 04/29/2019] [Accepted: 05/04/2019] [Indexed: 12/01/2022]
Abstract
Additive neurogenesis, the net increase in neuronal numbers by addition of new nerve cells to existing tissue, forms the basis for indeterminate spinal cord growth in brown ghost knifefish (Apteronotus leptorhynchus). Among the cells generated through the activity of adult neural stem cells are electromotoneurons, whose axons constitute the electric organ of this weakly electric fish. Electromotoneuron development is organized along a caudo-rostral gradient, with the youngest and smallest of these cells located near the caudal end of the spinal cord. Electromotoneurons start expressing calbindin-D28k when their somata have reached diameters of approximately 10 μm, and they continue expression after they have grown to a final size of about 50 μm. Calbindin-D28k expression is significantly increased in young neurons generated in response to injury. Immunohistochemical staining against caspase-3 revealed that electromotoneurons in both intact and regenerating spinal cord are significantly less likely to undergo apoptosis than the average spinal cord cell. We hypothesize that expression of calbindin-D28k protects electromotoneurons from cell death; and that the evolutionary development of such a neuroprotective mechanism has been driven by the indispensability of electromotoneurons in the fish's electric behavior, and by the high size-dependent costs associated with their production or removal upon cell death.
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Affiliation(s)
- Antonia G Vitalo
- Laboratory of Neurobiology, Department of Biology, Northeastern University, 134 Mugar Life Sciences, 360 Huntington Avenue, Boston, MA, 02115, USA
| | - Iulian Ilieş
- Healthcare Systems Engineering Institute, Department of Mechanical and Industrial Engineering, Northeastern University, Boston, MA, 02115, USA
| | - Günther K H Zupanc
- Laboratory of Neurobiology, Department of Biology, Northeastern University, 134 Mugar Life Sciences, 360 Huntington Avenue, Boston, MA, 02115, USA.
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Fronk AH, Kim LY, Craig JM, Crampton WGR, Albert JS. Sexual Size Dimorphism in the Macana Tigrina, Gymnotus javari (Gymnotidae, Gymnotiformes). COPEIA 2019. [DOI: 10.1643/ci-18-164] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- Aaron H. Fronk
- Department of Biology, University of Louisiana at Lafayette, P.O. Box 43602, Lafayette, Louisiana 70504; (AHF) C00226417@louisiana. edu; and (JSA) . Send reprint requests to AHF
| | - Lesley Y. Kim
- Department of Biology, University of Louisiana at Lafayette, P.O. Box 43602, Lafayette, Louisiana 70504; (AHF) C00226417@louisiana. edu; and (JSA) . Send reprint requests to AHF
| | - Jack M. Craig
- Department of Biology, University of Louisiana at Lafayette, P.O. Box 43602, Lafayette, Louisiana 70504; (AHF) C00226417@louisiana. edu; and (JSA) . Send reprint requests to AHF
| | - William G. R. Crampton
- Department of Biology, University of Central Florida, Biological Sciences Bldg., 4110 Libra Drive, Orlando, Florida 32816-2368;
| | - James S. Albert
- Department of Biology, University of Louisiana at Lafayette, P.O. Box 43602, Lafayette, Louisiana 70504; (AHF) C00226417@louisiana. edu; and (JSA) . Send reprint requests to AHF
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Albertson RC, Kawasaki KC, Tetrault ER, Powder KE. Genetic analyses in Lake Malawi cichlids identify new roles for Fgf signaling in scale shape variation. Commun Biol 2018; 1:55. [PMID: 30271938 PMCID: PMC6123627 DOI: 10.1038/s42003-018-0060-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 04/30/2018] [Indexed: 01/30/2023] Open
Abstract
Elasmoid scales are the most common epithelial appendage among vertebrates, however an understanding of the genetic mechanisms that underlie variation in scale shape is lacking. Using an F2 mapping cross between morphologically distinct cichlid species, we identified >40 QTL for scale shape at different body positions. We show that while certain regions of the genome regulate variation in multiple scales, most are specific to scales at distinct positions. This suggests a degree of regional modularity in scale development. We also identified a single QTL for variation in scale shape disparity across the body. Finally, we screened a QTL hotspot for candidate loci, and identified the Fgf receptor fgfr1b as a prime target. Quantitative rtPCR and small molecule manipulation support a role for Fgf signaling in shaping cichlid scales. While Fgfs have previously been implicated in scale loss, these data reveal new roles for the pathway in scale shape variation.
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Affiliation(s)
- R Craig Albertson
- Department of Biology, University of Massachusetts, 611 North Pleasant Street, Amherst, MA, 01003, USA.
| | - Kenta C Kawasaki
- Graduate Program in Molecular and Cellular Biology, University of Massachusetts, 611 North Pleasant Street, Amherst, MA, 01003, USA
| | - Emily R Tetrault
- Graduate Program in Molecular and Cellular Biology, University of Massachusetts, 611 North Pleasant Street, Amherst, MA, 01003, USA
| | - Kara E Powder
- Department of Biological Sciences, Clemson University, 190 Collings Street, Clemson, SC, 29634, USA
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Sîrbulescu RF, Ilieş I, Meyer A, Zupanc GKH. Additive neurogenesis supported by multiple stem cell populations mediates adult spinal cord development: A spatiotemporal statistical mapping analysis in a teleost model of indeterminate growth. Dev Neurobiol 2017; 77:1269-1307. [PMID: 28707354 DOI: 10.1002/dneu.22511] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 07/07/2017] [Accepted: 07/09/2017] [Indexed: 01/15/2023]
Abstract
The knifefish Apteronotus leptorhynchus exhibits indeterminate growth throughout adulthood. This phenomenon extends to the spinal cord, presumably through the continuous addition of new neurons and glial cells. However, little is known about the developmental dynamics of cells added during adult growth. The present work characterizes the structural and functional development of the adult spinal cord in this model organism through a comprehensive quantitative analysis of the spatial and temporal dynamics of new cells at various developmental stages. This analysis, based on a novel statistical mapping approach, revealed within the adult spinal cord a wide distribution of both mitotically active and quiescent Sox2-expressing stem/progenitor cells (SPCs). While such cells are particularly concentrated within the ependymal layer near the central canal, the majority of them reside in the parenchyma, resembling the distribution of SPCs observed in the mammalian spinal cord. The active SPCs in the adult knifefish spinal cord give rise to transit amplifying progenitor cells that undergo a few additional mitotic divisions before developing into Hu C/D+ neurons and S100+ glial cells. There is no evidence of long-distance migration of the newborn cells. The persistence of cell proliferation and differentiation, combined with low levels of apoptosis, leads to a continuous addition of cells to the existing tissue. Newly generated neurons have functional and behavioral relevance, as indicated by the integration of axons of new electromotor neurons into the electric organ of these weakly electric fish. This results in a gradual increase in the amplitude of the electric organ discharge during adult development. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 77: 1269-1307, 2017.
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Affiliation(s)
- Ruxandra F Sîrbulescu
- Laboratory of Neurobiology, Department of Biology, Northeastern University, Boston, Massachusetts
| | - Iulian Ilieş
- Laboratory of Neurobiology, Department of Biology, Northeastern University, Boston, Massachusetts
| | - Annette Meyer
- Laboratory of Neurobiology, Department of Biology, Northeastern University, Boston, Massachusetts
| | - Günther K H Zupanc
- Laboratory of Neurobiology, Department of Biology, Northeastern University, Boston, Massachusetts
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Luo WW, Liu CS, Cao XJ, Huang LF, Huang SQ. Precision of age estimations from scales, otoliths, vertebrae, opercular bones and cleithra of two loaches,Misgurnus anguillicaudatusandParamisgurnus dabryanus. FOLIA ZOOLOGICA 2016. [DOI: 10.25225/fozo.v65.i3.a2.2016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Wei-Wei Luo
- College of Fisheries, Key Lab of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education/Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Wuhan 437000, Hubei, People's Republic of China;, , , ,
| | - Chuan-Shu Liu
- College of Fisheries, Key Lab of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education/Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Wuhan 437000, Hubei, People's Republic of China;, , , ,
| | - Xiao-Juan Cao
- College of Fisheries, Key Lab of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education/Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Wuhan 437000, Hubei, People's Republic of China;, , , ,
- Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Hubei, People's Republic of China
| | - Long-Fei Huang
- College of Fisheries, Key Lab of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education/Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Wuhan 437000, Hubei, People's Republic of China;, , , ,
| | - Song-Qian Huang
- College of Fisheries, Key Lab of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education/Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Wuhan 437000, Hubei, People's Republic of China;, , , ,
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Ilieş I, Sîrbulescu RF, Zupanc GK. Indeterminate body growth and lack of gonadal decline in the brown ghost knifefish (Apteronotus leptorhynchus), an organism exhibiting negligible brain senescence. CAN J ZOOL 2014. [DOI: 10.1139/cjz-2014-0109] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The brown ghost knifefish (Apteronotus leptorhynchus (Ellis in Eigenmann, 1912)) is the only vertebrate organism identified thus far that exhibits negligible brain senescence. The present study examines the basic growth patterns of this species, testing the hypothesis that indeterminate growth and lack of reproductive senescence correlate with negligible senescence. Analysis of length–mass relationships revealed negative allometric growth in males and isometric growth in females. Total length at first sexual maturity was 13.5 cm in males and 12.0 cm in females, whereas gonadal mass was 0.02 g in males and 0.2 g in females. Modelling of total length as a function of the number of otolith rings using attenuating growth equations revealed that lengths of up to 26.8 cm in males and 20.2 cm in females can be reached, indicating that the fish continue to grow throughout life. Gonadal mass increased significantly with age in sexually immature individuals of both sexes. In sexually mature fish, gonadal mass showed a marginal increase with age in males and no change in females. The demonstration of indeterminate growth of the fish and of the lack of gonadal regression with age has important implications for the characterization of brown ghost knifefish as a model of negligible senescence.
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Affiliation(s)
- Iulian Ilieş
- Laboratory of Neurobiology, Department of Biology, Northeastern University, 134 Mugar Life Science Building, 360 Huntington Avenue, Boston, MA 02115, USA
| | - Ruxandra F. Sîrbulescu
- Laboratory of Neurobiology, Department of Biology, Northeastern University, 134 Mugar Life Science Building, 360 Huntington Avenue, Boston, MA 02115, USA
| | - Günther K.H. Zupanc
- Laboratory of Neurobiology, Department of Biology, Northeastern University, 134 Mugar Life Science Building, 360 Huntington Avenue, Boston, MA 02115, USA
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Sîrbulescu RF, Ilieş I, Vitalo AG, Trull K, Zhu J, Traniello IM, Zupanc GK. Adult stem cells in the knifefish cerebellum. Dev Neurobiol 2014; 75:39-65. [DOI: 10.1002/dneu.22210] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Revised: 07/06/2014] [Accepted: 07/07/2014] [Indexed: 01/22/2023]
Affiliation(s)
- Ruxandra F. Sîrbulescu
- Laboratory of Neurobiology, Department of Biology; Northeastern University; Boston Massachusetts 02115
| | - Iulian Ilieş
- Laboratory of Neurobiology, Department of Biology; Northeastern University; Boston Massachusetts 02115
| | - Antonia G. Vitalo
- Laboratory of Neurobiology, Department of Biology; Northeastern University; Boston Massachusetts 02115
| | - Krystal Trull
- Laboratory of Neurobiology, Department of Biology; Northeastern University; Boston Massachusetts 02115
| | - Jenny Zhu
- Laboratory of Neurobiology, Department of Biology; Northeastern University; Boston Massachusetts 02115
| | - Ian M. Traniello
- Laboratory of Neurobiology, Department of Biology; Northeastern University; Boston Massachusetts 02115
| | - Günther K.H. Zupanc
- Laboratory of Neurobiology, Department of Biology; Northeastern University; Boston Massachusetts 02115
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