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Ávila-Mendoza J, Urban-Sosa VA, Lazcano I, Orozco A, Luna M, Martínez-Moreno CG, Arámburo C. Comparative analysis of Krüppel-like factors expression in the retinas of zebrafish and mice during development and after injury. Gen Comp Endocrinol 2024; 356:114579. [PMID: 38964422 DOI: 10.1016/j.ygcen.2024.114579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2024] [Revised: 06/25/2024] [Accepted: 06/28/2024] [Indexed: 07/06/2024]
Abstract
The Krüppel-like factors (KLFs) have emerged as important transcriptional regulators of various cellular processes, including neural development. Some of them have been described as intrinsic factors involved in axon regeneration in the central nervous system (CNS) of vertebrates. Zebrafish are known for their ability to regenerate several tissues in adulthood, including the CNS, a capability lost during vertebrate evolution and absent in adult mammals. The role that KLFs could play in this differential ability remains unknown. Therefore, in this study, we analyzed the endogenous response of certain KLFs implicated in axon regeneration (KLFs 6, 7, 9, and 13) during retina development and after axon injury. The results showed that the expression of Klfs 6, 7, and 13 decreases in the developing retina of mice but not in zebrafish, while the mRNA levels of Klf9 strongly increase in both species. The response to injury was further analyzed using optic nerve crush (ONC) as a model of lesion. Our analysis during the acute phase (hours) demonstrated an induction of Klfs 6 and 7 expression exclusively in the zebrafish retina, while Klfs 9 and 13 mRNA levels increased in both species. Further analysis of the chronic response (days) showed that mRNA levels of Klf6 transiently increase in the retinas of both zebrafish and mice, whereas those of Klf7 decrease later after optic nerve injury. In addition, the analysis revealed that the expression of Klf9 decreases, while that of Klf13 increases in the retinas of zebrafish in response to optic nerve injury but remains unaltered in mice. Altogether, these findings support the hypothesis that KLFs may play a role in the differential axon regeneration abilities exhibited by fish and mice.
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Affiliation(s)
- José Ávila-Mendoza
- Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Campus Juriquilla, Universidad Nacional Autónoma de México, Querétaro 76230, Mexico.
| | - Valeria A Urban-Sosa
- Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Campus Juriquilla, Universidad Nacional Autónoma de México, Querétaro 76230, Mexico
| | - Iván Lazcano
- Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Campus Juriquilla, Universidad Nacional Autónoma de México, Querétaro 76230, Mexico
| | - Aurea Orozco
- Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Campus Juriquilla, Universidad Nacional Autónoma de México, Querétaro 76230, Mexico
| | - Maricela Luna
- Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Campus Juriquilla, Universidad Nacional Autónoma de México, Querétaro 76230, Mexico
| | - Carlos G Martínez-Moreno
- Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Campus Juriquilla, Universidad Nacional Autónoma de México, Querétaro 76230, Mexico
| | - Carlos Arámburo
- Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Campus Juriquilla, Universidad Nacional Autónoma de México, Querétaro 76230, Mexico.
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2
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Abraham E, Hartmann H, Yoshimatsu T, Baden T, Brand M. Restoration of cone-circuit functionality in the regenerating adult zebrafish retina. Dev Cell 2024; 59:2158-2170.e6. [PMID: 39096897 DOI: 10.1016/j.devcel.2024.07.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 05/28/2024] [Accepted: 07/09/2024] [Indexed: 08/05/2024]
Abstract
Unlike humans, teleosts like zebrafish exhibit robust retinal regeneration after injury from endogenous stem cells. However, it is unclear if regenerating cone photoreceptors regain physiological function and integrate correctly into post-synaptic circuits. We used two-photon calcium imaging of living adult retina to examine photoreceptor responses before and after light-induced lesions. To assess functional recovery of cones and downstream outer retinal circuits, we exploited color opponency; UV cones exhibit intrinsic Off-response to blue light, but On-response to green light, which depends on feedback signals from outer retinal circuits. Accordingly, we assessed the presence and quality of Off- vs. On-responses and found that regenerated UV cones regain both Off-responses to short-wavelength and On-responses to long-wavelength light within 3 months after lesion. Therefore, physiological circuit functionality is restored in regenerated cone photoreceptors, suggesting that inducing endogenous regeneration is a promising strategy for human retinal repair.
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Affiliation(s)
- Evelyn Abraham
- CRTD - Center for Regenerative Therapies TU Dresden, CMCB, Technische Universität Dresden, Fetscherstraße 105, 01307 Dresden, Germany
| | - Hella Hartmann
- CMCB - Center for Molecular and Cellular Bioengineering, Technische Universität Dresden, Tatzberg 47-51, 01307 Dresden, Germany
| | - Takeshi Yoshimatsu
- School of Life Sciences, University of Sussex, Biology Road, Brighton BN1 9QG, UK
| | - Tom Baden
- School of Life Sciences, University of Sussex, Biology Road, Brighton BN1 9QG, UK
| | - Michael Brand
- CRTD - Center for Regenerative Therapies TU Dresden, CMCB, Technische Universität Dresden, Fetscherstraße 105, 01307 Dresden, Germany; CMCB - Center for Molecular and Cellular Bioengineering, Technische Universität Dresden, Tatzberg 47-51, 01307 Dresden, Germany; PoL - Excellence Cluster Physics of Life, TU Dresden, Fetscherstrasse 105, 01307 Dresden, Germany.
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3
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Rozofsky JP, Pozzuto JM, Byrd-Jacobs CA. Mitral Cell Dendritic Morphology in the Adult Zebrafish Olfactory Bulb following Growth, Injury and Recovery. Int J Mol Sci 2024; 25:5030. [PMID: 38732248 PMCID: PMC11084181 DOI: 10.3390/ijms25095030] [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: 03/25/2024] [Revised: 05/03/2024] [Accepted: 05/04/2024] [Indexed: 05/13/2024] Open
Abstract
The role of afferent target interactions in dendritic plasticity within the adult brain remains poorly understood. There is a paucity of data regarding the effects of deafferentation and subsequent dendritic recovery in adult brain structures. Moreover, although adult zebrafish demonstrate ongoing growth, investigations into the impact of growth on mitral cell (MC) dendritic arbor structure and complexity are lacking. Leveraging the regenerative capabilities of the zebrafish olfactory system, we conducted a comprehensive study to address these gaps. Employing an eight-week reversible deafferentation injury model followed by retrograde labeling, we observed substantial morphological alterations in MC dendrites. Our hypothesis posited that cessation of injury would facilitate recovery of MC dendritic arbor structure and complexity, potentially influenced by growth dynamics. Statistical analyses revealed significant changes in MC dendritic morphology following growth and recovery periods, indicating that MC total dendritic branch length retained significance after 8 weeks of deafferentation injury when normalized to individual fish physical characteristics. This suggests that regeneration of branch length could potentially function relatively independently of growth-related changes. These findings underscore the remarkable plasticity of adult dendritic arbor structures in a sophisticated model organism and highlight the efficacy of zebrafish as a vital implement for studying neuroregenerative processes.
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Affiliation(s)
- John P. Rozofsky
- Department of Biological Sciences, Western Michigan University, 1903 W Michigan Ave., Kalamazoo, MI 49009, USA;
| | - Joanna M. Pozzuto
- Department of Biology, Kalamazoo Valley Community College, 6767 W O Ave., Kalamazoo, MI 49009, USA;
| | - Christine A. Byrd-Jacobs
- Department of Biological Sciences, Western Michigan University, 1903 W Michigan Ave., Kalamazoo, MI 49009, USA;
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4
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Farre AA, Thomas P, Huang J, Poulsen RA, Owusu Poku E, Stenkamp DL. Plasticity of cone photoreceptors in adult zebrafish revealed by thyroid hormone exposure. Sci Rep 2023; 13:15697. [PMID: 37735192 PMCID: PMC10514274 DOI: 10.1038/s41598-023-42686-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Accepted: 09/13/2023] [Indexed: 09/23/2023] Open
Abstract
Vertebrate color vision is predominantly mediated by the presence of multiple cone photoreceptor subtypes that are each maximally sensitive to different wavelengths of light. Thyroid hormone (TH) has been shown to be essential in the spatiotemporal patterning of cone subtypes in many species, including cone subtypes that express opsins that are encoded by tandemly replicated genes. TH has been shown to differentially regulate the tandemly replicated lws opsin genes in zebrafish, and exogenous treatments alter the expression levels of these genes in larvae and juveniles. In this study, we sought to determine whether gene expression in cone photoreceptors remains plastic to TH treatment in adults. We used a transgenic lws reporter line, multiplexed fluorescence hybridization chain reaction in situ hybridization, and qPCR to examine the extent to which cone gene expression can be altered by TH in adults. Our studies revealed that opsin gene expression, and the expression of other photoreceptor genes, remains plastic to TH treatment in adult zebrafish. In addition to retinal plasticity, exogenous TH treatment alters skin pigmentation patterns in adult zebrafish after 5 days. Taken together, our results show a remarkable level of TH-sensitive plasticity in the adult zebrafish.
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Affiliation(s)
- Ashley A Farre
- Department of Biological Sciences, University of Idaho, Moscow, ID, 83844-3015, USA
| | - Preston Thomas
- WWAMI Medical Education Program, University of Washington School of Medicine, University of Idaho, Moscow, ID, USA
| | - Johnson Huang
- University of Washington School of Medicine, Spokane, WA, USA
| | | | - Emmanuel Owusu Poku
- Department of Biological Sciences, University of Idaho, Moscow, ID, 83844-3015, USA
| | - Deborah L Stenkamp
- Department of Biological Sciences, University of Idaho, Moscow, ID, 83844-3015, USA.
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5
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Live Cell Imaging of Dynamic Processes in Adult Zebrafish Retinal Cross-Section Cultures. Methods Mol Biol 2023; 2636:367-388. [PMID: 36881311 DOI: 10.1007/978-1-0716-3012-9_20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/08/2023]
Abstract
Following retinal injury, zebrafish possess the remarkable capacity to endogenously regenerate lost retinal neurons from Müller glia-derived neuronal progenitor cells. Additionally, neuronal cell types that are undamaged and persist in the injured retina are also produced. Thus, the zebrafish retina is an excellent system to study the integration of all neuronal cell types into an existing neuronal circuit. The few studies that examined axonal/dendritic outgrowth and the establishment of synaptic contacts by regenerated neurons predominantly utilized fixed tissue samples. We recently established a flatmount culture model to monitor Müller glia nuclear migration in real time by two-photon microscopy. However, in retinal flatmounts, z-stacks of the entire retinal z-dimension have to be acquired to image cells that extend through parts or the entirety of the neural retina, such as bipolar cells and Müller glia, respectively. Cellular processes with fast kinetics might thus be missed. Therefore, we generated a retinal cross-section culture from light-damaged zebrafish to image the entire Müller glia in one z-plane. Isolated dorsal retinal hemispheres were cut into two dorsal quarters and mounted with the cross-section view facing the coverslips of culture dishes, which allowed monitoring Müller glia nuclear migration using confocal microscopy. Confocal imaging of cross-section cultures is ultimately also applicable to live cell imaging of axon/dendrite formation of regenerated bipolar cells, while the flatmount culture model will be more suitable to monitor axon outgrowth of ganglion cells.
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Mitchell DM, Stenkamp DL. Generating Widespread and Scalable Retinal Lesions in Adult Zebrafish by Intraocular Injection of Ouabain. Methods Mol Biol 2023; 2636:221-235. [PMID: 36881303 DOI: 10.1007/978-1-0716-3012-9_12] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/08/2023]
Abstract
Zebrafish regenerate functional retinal neurons after injury. Regeneration takes place following photic, chemical, mechanical, surgical, or cryogenic lesions, as well as after lesions that selectively target specific neuronal cell populations. An advantage of chemical retinal lesion for studying the process of regeneration is that the lesion is topographically widespread. This results in the loss of visual function as well as a regenerative response that engages nearly all stem cells (Müller glia). Such lesions can therefore be used to further our understanding of the process and mechanisms underlying re-establishment of neuronal wiring patterns, retinal function, and visually mediated behaviors. Widespread chemical lesions also permit the quantitative analysis of gene expression throughout the retina during the period of initial damage and over the duration of regeneration, as well as the study of growth and targeting of axons of regenerated retinal ganglion cells. The neurotoxic Na+/K+ ATPase inhibitor ouabain specifically offers a further advantage over other types of chemical lesions in that it is scalable; the extent of damage can be targeted to include only inner retinal neurons, or all retinal neurons, simply by adjusting the intraocular concentration of ouabain that is used. Here we describe the procedure through which these "selective" vs. "extensive" retinal lesions can be generated.
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Affiliation(s)
- Diana M Mitchell
- Department of Biological Sciences, University of Idaho, Moscow, ID, USA.
| | - Deborah L Stenkamp
- Department of Biological Sciences, University of Idaho, Moscow, ID, USA.
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Barrett LM, Meighan PC, Mitchell DM, Varnum MD, Stenkamp DL. Assessing Rewiring of the Retinal Circuitry by Electroretinogram (ERG) After Inner Retinal Lesion in Adult Zebrafish. Methods Mol Biol 2023; 2636:421-435. [PMID: 36881314 DOI: 10.1007/978-1-0716-3012-9_23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/08/2023]
Abstract
Adult zebrafish respond to retinal injury with a regenerative response that replaces damaged neurons with Müller glia-derived regenerated neurons. The regenerated neurons are functional, appear to make appropriate synaptic connections, and support visually mediated reflexes and more complex behaviors. Curiously, the electrophysiology of damaged, regenerating, and regenerated zebrafish retina has only recently been examined. In our previous work, we demonstrated that electroretinogram (ERG) recordings of damaged zebrafish retina correlate with the extent of the inflicted damage and that the regenerated retina at 80 days post-injury exhibited ERG waveforms consistent with functional visual processing. In this paper we describe the procedure for obtaining and analyzing ERG recordings from adult zebrafish previously subjected to widespread lesions that destroy inner retinal neurons and engage a regenerative response that restores retinal function, in particular the synaptic connections between photoreceptor axon terminals and the dendritic trees of retinal bipolar neurons.
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Affiliation(s)
- Lindsey M Barrett
- Department of Biological Sciences, University of Idaho, Moscow, ID, USA
| | - Peter C Meighan
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, WA, USA
| | - Diana M Mitchell
- Department of Biological Sciences, University of Idaho, Moscow, ID, USA
| | - Michael D Varnum
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, WA, USA
| | - Deborah L Stenkamp
- Department of Biological Sciences, University of Idaho, Moscow, ID, USA.
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Frey RA, Barrett LM, Parkin L, Blakeley B, Ålund M, Byford G, Euhus A, Tsarnas C, Boughman JW, Stenkamp DL. Eye flukes (Diplostomum spp) damage retinal tissue and may cause a regenerative response in wild threespine stickleback fish. Exp Eye Res 2022; 225:109298. [PMID: 36288754 DOI: 10.1016/j.exer.2022.109298] [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: 08/14/2022] [Revised: 10/11/2022] [Accepted: 10/18/2022] [Indexed: 01/29/2023]
Abstract
Fish rely upon vision as a dominant sensory system for foraging, predator avoidance, and mate selection. Damage to the visual system, in particular to the neural retina of the eye, has been demonstrated to result in a regenerative response in captive fish that serve as model organisms (e.g. zebrafish), and this response restores some visual function. The purpose of the present study is to determine whether damage to the visual system that occurs in wild populations of fish also results in a regenerative response, offering a potentially ecologically relevant model of retinal regeneration. Adult threespine stickleback were collected from several water bodies of Iceland, and cryosectioned eye tissues were processed for hematoxylin and eosin staining or for indirect immunofluorescence using cell-specific markers. In many of the samples, eye flukes (metacercariae of Diplostomum spp) were present, frequently between the neural retina and retinal pigmented epithelium (RPE). Damage to the retina and to the RPE was evident in eyes containing flukes, and RPE fragments were observed within fluke bodies, suggesting they had consumed this eye tissue. Expression of a cell proliferation marker was also observed in both retina and RPE, consistent with a proliferative response to the damage. Interestingly, some regions of infected retina displayed "laminar fusions," in which neuronal cell bodies were misplaced within the major synaptic layer of the retina. These laminar fusions are also frequently found in regenerated zebrafish retina following non-parasitic (experimental) forms of retinal damage. The stickleback retina may therefore respond to fluke-mediated damage by engaging in retinal regeneration.
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Affiliation(s)
- Ruth A Frey
- Department of Biological Sciences, University of Idaho, Moscow, ID, 83844, USA
| | - Lindsey M Barrett
- Department of Biological Sciences, University of Idaho, Moscow, ID, 83844, USA
| | - Lauren Parkin
- Department of Biological Sciences, University of Idaho, Moscow, ID, 83844, USA
| | - Brittany Blakeley
- Department of Biological Sciences, University of Idaho, Moscow, ID, 83844, USA
| | - Murielle Ålund
- Department of Integrative Biology, Michigan State University, Lansing, MI, 48824, USA
| | - Gregory Byford
- Department of Integrative Biology, Michigan State University, Lansing, MI, 48824, USA
| | - Abigail Euhus
- Department of Biological Sciences, University of Idaho, Moscow, ID, 83844, USA
| | - Christine Tsarnas
- Department of Biological Sciences, University of Idaho, Moscow, ID, 83844, USA
| | - Janette W Boughman
- Department of Integrative Biology, Michigan State University, Lansing, MI, 48824, USA
| | - Deborah L Stenkamp
- Department of Biological Sciences, University of Idaho, Moscow, ID, 83844, USA.
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Barrett LM, Mitchell DM, Meighan PC, Varnum MD, Stenkamp DL. Dynamic functional and structural remodeling during retinal regeneration in zebrafish. Front Mol Neurosci 2022; 15:1070509. [PMID: 36533135 PMCID: PMC9748287 DOI: 10.3389/fnmol.2022.1070509] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 11/14/2022] [Indexed: 12/03/2022] Open
Abstract
Introduction Zebrafish regenerate their retinas following damage, resulting in restoration of visual function. Here we evaluate recovery of retinal function through qualitative and quantitative analysis of the electroretinogram (ERG) over time following retinal damage, in correlation to histological features of regenerated retinal tissue. Methods Retinas of adult zebrafish were lesioned by intravitreal injection of 10 μM (extensive lesion; destroys all neurons) or 2 μM (selective lesion; spares photoreceptors) ouabain. Unlesioned contralateral retinas served as controls. Function of retinal circuitry was analyzed at selected timepoints using ERG recordings from live zebrafish, and whole eyes were processed for histological analyses immediately thereafter. Results Qualitative and quantitative assessment of waveforms during retinal regeneration revealed dynamic changes that were heterogeneous on an individual level within each sampling time, but still followed common waveform recovery patterns on a per-fish and population-level basis. Early in the regeneration period (13-30 days post injury; DPI), for both lesion types, b-waves were essentially not detected, and unmasked increased apparent amplitudes, implicit times, and half-widths of a-waves (vs. controls). In control recordings, d-waves were not obviously detected, but apparent d-waves (OFF-bipolar responses) from regenerating retinas of several fish became prominent by 30DPI and dominated the post-photoreceptor response (PPR). Beyond 45DPI, b-waves became detectable, and the ratio of apparent d- to b-wave contributions progressively shifted with most, but not all, fish displaying a b-wave dominated PPR. At the latest timepoints (extensive, 90DPI; selective, 80DPI), recordings with measurable b-waves approached a normal waveform (implicit times and half-widths), but amplitudes were not restored to control levels. Histological analyses of the retinas from which ERGs were recorded showed that as regeneration progressed, PKCa + ON-bipolar terminals and parvalbumin + amacrine cell processes became more stereotypically positioned within the deep sublaminae of the INL over recovery time after each lesion type, consistent with the shift in PPR seen in the ERG recordings. Discussion Taken together, these data suggest that photoreceptor-OFF-bipolar component/connectivity may functionally recover and mature earlier during regeneration compared to the photoreceptor-ON-bipolar component, though the timeframe in which such recovery happens is heterogeneous on a per-fish basis. Collectively our studies suggest gradual restoration of ON-bipolar functional circuitry during retinal regeneration.
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Affiliation(s)
- Lindsey M. Barrett
- Department of Biological Sciences, University of Idaho, Moscow, ID, United States
| | - Diana M. Mitchell
- Department of Biological Sciences, University of Idaho, Moscow, ID, United States
| | - Peter C. Meighan
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, WA, United States
| | - Michael D. Varnum
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, WA, United States
| | - Deborah L. Stenkamp
- Department of Biological Sciences, University of Idaho, Moscow, ID, United States,*Correspondence: Deborah L. Stenkamp,
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Todd L, Reh TA. Comparative Biology of Vertebrate Retinal Regeneration: Restoration of Vision through Cellular Reprogramming. Cold Spring Harb Perspect Biol 2022; 14:a040816. [PMID: 34580118 PMCID: PMC9248829 DOI: 10.1101/cshperspect.a040816] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The regenerative capacity of the vertebrate retina varies substantially across species. Whereas fish and amphibians can regenerate functional retina, mammals do not. In this perspective piece, we outline the various strategies nonmammalian vertebrates use to achieve functional regeneration of vision. We review key differences underlying the regenerative potential across species including the cellular source of postnatal progenitors, the diversity of cell fates regenerated, and the level of functional vision that can be achieved. Finally, we provide an outlook on the field of engineering the mammalian retina to replace neurons lost to injury or disease.
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Affiliation(s)
- Levi Todd
- Department of Biological Structure, University of Washington, Seattle, Washington 98195, USA
| | - Thomas A Reh
- Department of Biological Structure, University of Washington, Seattle, Washington 98195, USA
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Zhang Q, Li Y, Zhuo Y. Synaptic or Non-synaptic? Different Intercellular Interactions with Retinal Ganglion Cells in Optic Nerve Regeneration. Mol Neurobiol 2022; 59:3052-3072. [PMID: 35266115 PMCID: PMC9016027 DOI: 10.1007/s12035-022-02781-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 02/24/2022] [Indexed: 12/31/2022]
Abstract
Axons of adult neurons in the mammalian central nervous system generally fail to regenerate by themselves, and few if any therapeutic options exist to reverse this situation. Due to a weak intrinsic potential for axon growth and the presence of strong extrinsic inhibitors, retinal ganglion cells (RGCs) cannot regenerate their axons spontaneously after optic nerve injury and eventually undergo apoptosis, resulting in permanent visual dysfunction. Regarding the extracellular environment, research to date has generally focused on glial cells and inflammatory cells, while few studies have discussed the potentially significant role of interneurons that make direct connections with RGCs as part of the complex retinal circuitry. In this study, we provide a novel angle to summarize these extracellular influences following optic nerve injury as "intercellular interactions" with RGCs and classify these interactions as synaptic and non-synaptic. By discussing current knowledge of non-synaptic (glial cells and inflammatory cells) and synaptic (mostly amacrine cells and bipolar cells) interactions, we hope to accentuate the previously neglected but significant effects of pre-synaptic interneurons and bring unique insights into future pursuit of optic nerve regeneration and visual function recovery.
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Affiliation(s)
- Qi Zhang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Sun Yat-Sen University, Guangzhou, 510060, China
| | - Yiqing Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Sun Yat-Sen University, Guangzhou, 510060, China.
| | - Yehong Zhuo
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Sun Yat-Sen University, Guangzhou, 510060, China.
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12
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Hammer J, Röppenack P, Yousuf S, Schnabel C, Weber A, Zöller D, Koch E, Hans S, Brand M. Visual Function is Gradually Restored During Retina Regeneration in Adult Zebrafish. Front Cell Dev Biol 2022; 9:831322. [PMID: 35178408 PMCID: PMC8844564 DOI: 10.3389/fcell.2021.831322] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 12/30/2021] [Indexed: 12/20/2022] Open
Abstract
In comparison to mammals, zebrafish are able to regenerate many organs and tissues, including the central nervous system (CNS). Within the CNS-derived neural retina, light lesions result in a loss of photoreceptors and the subsequent activation of Müller glia, the retinal stem cells. Müller glia-derived progenitors differentiate and eventually restore the anatomical tissue architecture within 4 weeks. However, little is known about how light lesions impair vision functionally, as well as how and to what extent visual function is restored during the course of regeneration, in particular in adult animals. Here, we applied quantitative behavioral assays to assess restoration of visual function during homeostasis and regeneration in adult zebrafish. We developed a novel vision-dependent social preference test, and show that vision is massively impaired early after lesion, but is restored to pre-lesion levels within 7 days after lesion. Furthermore, we employed a quantitative optokinetic response assay with different degrees of difficulty, similar to vision tests in humans. We found that vision for easy conditions with high contrast and low level of detail, as well as color vision, was restored around 7–10 days post lesion. Vision under more demanding conditions, with low contrast and high level of detail, was regained only later from 14 days post lesion onwards. Taken together, we conclude that vision based on contrast sensitivity, spatial resolution and the perception of colors is restored after light lesion in adult zebrafish in a gradual manner.
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Affiliation(s)
- Juliane Hammer
- CRTD-Center for Regenerative Therapies at TU Dresden, Dresden, Germany
| | - Paul Röppenack
- CRTD-Center for Regenerative Therapies at TU Dresden, Dresden, Germany
| | - Sarah Yousuf
- CRTD-Center for Regenerative Therapies at TU Dresden, Dresden, Germany
| | - Christian Schnabel
- Clinical Sensoring and Monitoring, Department of Anesthesiology and Intensive Care Medicine, Carl Gustav Carus Faculty of Medicine, TU Dresden, Dresden, Germany
| | - Anke Weber
- CRTD-Center for Regenerative Therapies at TU Dresden, Dresden, Germany
| | - Daniela Zöller
- CRTD-Center for Regenerative Therapies at TU Dresden, Dresden, Germany
| | - Edmund Koch
- Clinical Sensoring and Monitoring, Department of Anesthesiology and Intensive Care Medicine, Carl Gustav Carus Faculty of Medicine, TU Dresden, Dresden, Germany
| | - Stefan Hans
- CRTD-Center for Regenerative Therapies at TU Dresden, Dresden, Germany
| | - Michael Brand
- CRTD-Center for Regenerative Therapies at TU Dresden, Dresden, Germany
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13
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Vanhunsel S, Bergmans S, Beckers A, Etienne I, Van Bergen T, De Groef L, Moons L. The age factor in optic nerve regeneration: Intrinsic and extrinsic barriers hinder successful recovery in the short-living killifish. Aging Cell 2022; 21:e13537. [PMID: 34927348 PMCID: PMC8761009 DOI: 10.1111/acel.13537] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 11/24/2021] [Accepted: 12/03/2021] [Indexed: 01/06/2023] Open
Abstract
As the mammalian central nervous system matures, its regenerative ability decreases, leading to incomplete or non-recovery from the neurodegenerative diseases and central nervous system insults that we are increasingly facing in our aging world population. Current neuroregenerative research is largely directed toward identifying the molecular and cellular players that underlie central nervous system repair, yet it repeatedly ignores the aging context in which many of these diseases appear. Using an optic nerve crush model in a novel biogerontology model, that is, the short-living African turquoise killifish, the impact of aging on injury-induced optic nerve repair was investigated. This work reveals an age-related decline in axonal regeneration in female killifish, with different phases of the repair process being affected depending on the age. Interestingly, as in mammals, both a reduced intrinsic growth potential and a non-supportive cellular environment seem to lie at the basis of this impairment. Overall, we introduce the killifish visual system and its age-dependent regenerative ability as a model to identify new targets for neurorepair in non-regenerating individuals, thereby also considering the effects of aging on neurorepair.
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Affiliation(s)
- Sophie Vanhunsel
- Neural Circuit Development and Regeneration Research GroupAnimal Physiology and Neurobiology SectionDepartment of BiologyKU LeuvenLeuvenBelgium
| | - Steven Bergmans
- Neural Circuit Development and Regeneration Research GroupAnimal Physiology and Neurobiology SectionDepartment of BiologyKU LeuvenLeuvenBelgium
| | - An Beckers
- Neural Circuit Development and Regeneration Research GroupAnimal Physiology and Neurobiology SectionDepartment of BiologyKU LeuvenLeuvenBelgium
| | | | | | - Lies De Groef
- Neural Circuit Development and Regeneration Research GroupAnimal Physiology and Neurobiology SectionDepartment of BiologyKU LeuvenLeuvenBelgium
- Leuven Brain InstituteLeuvenBelgium
| | - Lieve Moons
- Neural Circuit Development and Regeneration Research GroupAnimal Physiology and Neurobiology SectionDepartment of BiologyKU LeuvenLeuvenBelgium
- Leuven Brain InstituteLeuvenBelgium
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14
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Berrosteguieta I, Rosillo JC, Herrera ML, Olivera-Bravo S, Casanova G, Herranz-Pérez V, García-Verdugo JM, Fernández AS. Plasticity of cell proliferation in the retina of Austrolebias charrua fish under light and darkness conditions. CURRENT RESEARCH IN NEUROBIOLOGY 2022; 3:100042. [DOI: 10.1016/j.crneur.2022.100042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 05/18/2022] [Accepted: 05/23/2022] [Indexed: 10/18/2022] Open
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15
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Campbell LJ, Levendusky JL, Steines SA, Hyde DR. Retinal regeneration requires dynamic Notch signaling. Neural Regen Res 2021; 17:1199-1209. [PMID: 34782554 PMCID: PMC8643038 DOI: 10.4103/1673-5374.327326] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Retinal damage in the adult zebrafish induces Müller glia reprogramming to produce neuronal progenitor cells that proliferate and differentiate into retinal neurons. Notch signaling, which is a fundamental mechanism known to drive cell-cell communication, is required to maintain Müller glia in a quiescent state in the undamaged retina, and repression of Notch signaling is necessary for Müller glia to reenter the cell cycle. The dynamic regulation of Notch signaling following retinal damage also directs proliferation and neurogenesis of the Müller glia-derived progenitor cells in a robust regeneration response. In contrast, mammalian Müller glia respond to retinal damage by entering a prolonged gliotic state that leads to additional neuronal death and permanent vision loss. Understanding the dynamic regulation of Notch signaling in the zebrafish retina may aid efforts to stimulate Müller glia reprogramming for regeneration of the diseased human retina. Recent findings identified DeltaB and Notch3 as the ligand-receptor pair that serves as the principal regulators of zebrafish Müller glia quiescence. In addition, multiomics datasets and functional studies indicate that additional Notch receptors, ligands, and target genes regulate cell proliferation and neurogenesis during the regeneration time course. Still, our understanding of Notch signaling during retinal regeneration is limited. To fully appreciate the complex regulation of Notch signaling that is required for successful retinal regeneration, investigation of additional aspects of the pathway, such as post-translational modification of the receptors, ligand endocytosis, and interactions with other fundamental pathways is needed. Here we review various modes of Notch signaling regulation in the context of the vertebrate retina to put recent research in perspective and to identify open areas of inquiry.
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Affiliation(s)
- Leah J Campbell
- Department of Biological Sciences, Center for Zebrafish Research, Center for Stem Cells and Regenerative Medicine, University of Notre Dame, Notre Dame, IN, USA
| | - Jaclyn L Levendusky
- Department of Biological Sciences, Center for Zebrafish Research, Center for Stem Cells and Regenerative Medicine, University of Notre Dame, Notre Dame, IN, USA
| | - Shannon A Steines
- Department of Biological Sciences, Center for Zebrafish Research, Center for Stem Cells and Regenerative Medicine, University of Notre Dame, Notre Dame, IN, USA
| | - David R Hyde
- Department of Biological Sciences, Center for Zebrafish Research, Center for Stem Cells and Regenerative Medicine, University of Notre Dame, Notre Dame, IN, USA
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16
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Stenkamp DL, Viall DD, Mitchell DM. Evidence of regional specializations in regenerated zebrafish retina. Exp Eye Res 2021; 212:108789. [PMID: 34653519 DOI: 10.1016/j.exer.2021.108789] [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: 06/25/2021] [Revised: 09/08/2021] [Accepted: 10/09/2021] [Indexed: 10/20/2022]
Abstract
Adult zebrafish are capable of functional retinal regeneration following damage. A goal of vision science is to stimulate or permit a similar process in mammals to treat human retinal disease and trauma. Ideally such a process would reconstitute the stereotyped, two-dimensional topographic patterns and regional specializations of specific cell types, functionally important for representation of the visual field. An example in humans is the cone-rich fovea, essential for high-acuity color vision. Stereotyped, global topographic patterns of specific retinal cell types are also found in zebrafish, particularly for cone types expressing the tandemly-replicated lws (long wavelength-sensitive) and rh2 (middle wavelength-sensitive) opsins. Here we examine whether regionally specialized patterns of LWS1 and LWS2 cones are restored in regenerated retinas in zebrafish. Adult transgenic zebrafish carrying fluorescent reporters for lws1 and lws2 were subjected to retinal lesions that destroy all neurons but spare glia, via intraocular injection of the neurotoxin ouabain. Regenerated and contralateral control retinas were mounted whole or sectioned, and imaged. Overall spatial patterns of lws1 vs. lws2 opsin-expressing cones in regenerated retinas were remarkably similar to those of control retinas, with LWS1 cones in ventral/peripheral regions, and LWS2 cones in dorsal/central regions. However, LWS2 cones occupied a smaller fraction of regenerated retina, and several cones co-expressed the lws1 and lws2 reporters in regenerated retinas. Local patterns of regenerated LWS1 cones showed modest reductions in regularity. These results suggest that some of the regional patterning information, or the source of such signals, for LWS cone subtypes may be retained by undamaged cell types (Müller glia or RPE) and re-deployed during regeneration.
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Affiliation(s)
- Deborah L Stenkamp
- Department of Biological Sciences, University of Idaho, Moscow, ID, 82844, USA.
| | - Derek D Viall
- Department of Biological Sciences, University of Idaho, Moscow, ID, 82844, USA
| | - Diana M Mitchell
- Department of Biological Sciences, University of Idaho, Moscow, ID, 82844, USA
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17
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Neurodegeneration, Neuroprotection and Regeneration in the Zebrafish Retina. Cells 2021; 10:cells10030633. [PMID: 33809186 PMCID: PMC8000332 DOI: 10.3390/cells10030633] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 02/10/2021] [Accepted: 03/01/2021] [Indexed: 12/15/2022] Open
Abstract
Neurodegenerative retinal diseases, such as glaucoma and diabetic retinopathy, involve a gradual loss of neurons in the retina as the disease progresses. Central nervous system neurons are not able to regenerate in mammals, therefore, an often sought after course of treatment for neuronal loss follows a neuroprotective or regenerative strategy. Neuroprotection is the process of preserving the structure and function of the neurons that have survived a harmful insult; while regenerative approaches aim to replace or rewire the neurons and synaptic connections that were lost, or induce regrowth of damaged axons or dendrites. In order to test the neuroprotective effectiveness or the regenerative capacity of a particular agent, a robust experimental model of retinal neuronal damage is essential. Zebrafish are being used more often in this type of study because their eye structure and development is well-conserved between zebrafish and mammals. Zebrafish are robust genetic tools and are relatively inexpensive to maintain. The large array of functional and behavioral tests available in zebrafish makes them an attractive model for neuroprotection studies. Some common insults used to model retinal disease and study neuroprotection in zebrafish include intense light, chemical toxicity and mechanical damage. This review covers the existing retinal neuroprotection and regeneration literature in the zebrafish and highlights their potential for future studies.
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18
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Guo R, Li F, Lu M, Ge K, Gan L, Sheng D. LIM Homeobox 9 knockdown by morpholino does not affect zebrafish retinal development. Biol Open 2021; 10:bio.056382. [PMID: 33579692 PMCID: PMC7969587 DOI: 10.1242/bio.056382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
LIM homeobox 9 (Lhx9) is a member of the LIM homeodomain transcription factor family, which expresses and functions in various vertebrate tissues, such as the gonads and pineal gland. Previous studies on lhx9 in zebrafish have mainly focused on the brain. However, little is known about the expression pattern of lhx9 during embryogenesis. Here, we detected lhx9 expression in zebrafish embryos using whole-mount in situ hybridization and found lhx9 expressed in heart, pectoral fin, and retina during their development in zebrafish. We then detailed the expression of lhx9 in retinal development. To further investigate the function of Lhx9 in retinogenesis, we performed morpholino (MO) knockdown experiments and found that upon lhx9 knockdown by MO, larvae presented normal eye development, retinal neural development, differentiation, proliferation, apoptosis, and responses to light stimulus. We not only elaborated the expression pattern of lhx9 in zebrafish embryogenesis, but we also demonstrated that lhx9 knockdown by morpholino does not affect the zebrafish retinal development, and our study provides data for further understanding of the role of Lhx9 in zebrafish retinal development. Summary:lhx9 is expressed in the development of the zebrafish heart, pectoral fin, and retina, but lhx9 knockdown by morpholino does not affect zebrafish retinal development.
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Affiliation(s)
- Rui Guo
- Key Laboratory of Organ Development and Regeneration of Zhejiang Province, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 311100 Zhejiang, China.,College of Life Sciences, Zhejiang University, Hangzhou 310013 Zhejiang, China
| | - Fei Li
- Key Laboratory of Organ Development and Regeneration of Zhejiang Province, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 311100 Zhejiang, China
| | - Minxia Lu
- Key Laboratory of Organ Development and Regeneration of Zhejiang Province, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 311100 Zhejiang, China
| | - Kangkang Ge
- Hangzhou jingbai biotechnology Co, LTD., Hangzhou 310004 Zhejiang, China
| | - Lin Gan
- Key Laboratory of Organ Development and Regeneration of Zhejiang Province, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 311100 Zhejiang, China .,College of Life Sciences, Zhejiang University, Hangzhou 310013 Zhejiang, China
| | - Donglai Sheng
- Key Laboratory of Organ Development and Regeneration of Zhejiang Province, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 311100 Zhejiang, China
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19
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Lahne M, Brecker M, Jones SE, Hyde DR. The Regenerating Adult Zebrafish Retina Recapitulates Developmental Fate Specification Programs. Front Cell Dev Biol 2021; 8:617923. [PMID: 33598455 PMCID: PMC7882614 DOI: 10.3389/fcell.2020.617923] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 12/31/2020] [Indexed: 12/20/2022] Open
Abstract
Adult zebrafish possess the remarkable capacity to regenerate neurons. In the damaged zebrafish retina, Müller glia reprogram and divide to produce neuronal progenitor cells (NPCs) that proliferate and differentiate into both lost neuronal cell types and those unaffected by the damage stimulus, which suggests that developmental specification/differentiation programs might be recapitulated during regeneration. Quantitative real-time polymerase chain reaction revealed that developmental competence factors are expressed following photoreceptor damage induced by intense light or in a genetic rod photoreceptor cell ablation model. In both light- and N-Methyl-D-aspartic acid (NMDA)-damaged adult zebrafish retinas, NPCs, but not proliferating Müller glia, expressed fluorescent reporters controlled by promoters of ganglion (atoh7), amacrine (ptf1a), bipolar (vsx1), or red cone photoreceptor cell competence factors (thrb) in a temporal expression sequence. In both damage paradigms, atoh7:GFP was expressed first, followed by ptf1a:EGFP and lastly, vsx1:GFP, whereas thrb:Tomato was observed in NPCs at the same time as ptf1a:GFP following light damage but shifted alongside vsx1:GFP in the NMDA-damaged retina. Moreover, HuC/D, indicative of ganglion and amacrine cell differentiation, colocalized with atoh7:GFP prior to ptf1a:GFP expression in the ganglion cell layer, which was followed by Zpr-1 expression (red/green cone photoreceptors) in thrb:Tomato-positive cells in the outer nuclear layer in both damage paradigms, mimicking the developmental differentiation sequence. However, comparing NMDA- to light-damaged retinas, the fraction of PCNA-positive cells expressing atoh7:GFP increased, that of thrb:Tomato and vsx1:GFP decreased, and that of ptf1a:GFP remained similar. To summarize, developmental cell specification programs were recapitulated during retinal regeneration, which adapted to account for the cell type lost.
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Affiliation(s)
- Manuela Lahne
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, United States.,Center for Stem Cells and Regenerative Medicine, University of Notre Dame, Notre Dame, IN, United States.,Center for Zebrafish Research, University of Notre Dame, Notre Dame, IN, United States
| | - Margaret Brecker
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, United States.,Center for Stem Cells and Regenerative Medicine, University of Notre Dame, Notre Dame, IN, United States.,Center for Zebrafish Research, University of Notre Dame, Notre Dame, IN, United States
| | - Stuart E Jones
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, United States
| | - David R Hyde
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, United States.,Center for Stem Cells and Regenerative Medicine, University of Notre Dame, Notre Dame, IN, United States.,Center for Zebrafish Research, University of Notre Dame, Notre Dame, IN, United States
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20
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Issaka Salia O, Mitchell DM. Bioinformatic analysis and functional predictions of selected regeneration-associated transcripts expressed by zebrafish microglia. BMC Genomics 2020; 21:870. [PMID: 33287696 PMCID: PMC7720500 DOI: 10.1186/s12864-020-07273-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Accepted: 11/23/2020] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Unlike mammals, zebrafish have a remarkable capacity to regenerate a variety of tissues, including central nervous system tissue. The function of macrophages in tissue regeneration is of great interest, as macrophages respond and participate in the landscape of events that occur following tissue injury in all vertebrate species examined. Understanding macrophage populations in regenerating tissue (such as in zebrafish) may inform strategies that aim to regenerate tissue in humans. We recently published an RNA-seq experiment that identified genes enriched in microglia/macrophages in regenerating zebrafish retinas. Interestingly, a small number of transcripts differentially expressed by retinal microglia/macrophages during retinal regeneration did not have predicted orthologs in human or mouse. We reasoned that at least some of these genes could be functionally important for tissue regeneration, but most of these genes have not been studied experimentally and their functions are largely unknown. To reveal their possible functions, we performed a variety of bioinformatic analyses aimed at identifying the presence of functional protein domains as well as orthologous relationships to other species. RESULTS Our analyses identified putative functional domains in predicted proteins for a number of selected genes. For example, we confidently predict kinase function for one gene, cytokine/chemokine function for another, and carbohydrate enzymatic function for a third. Predicted orthologs were identified for some, but not all, genes in species with described regenerative capacity, and functional domains were consistent with identified orthologs. Comparison to other published gene expression datasets suggest that at least some of these genes could be important in regenerative responses in zebrafish and not necessarily in response to microbial infection. CONCLUSIONS This work reveals previously undescribed putative function of several genes implicated in regulating tissue regeneration. This will inform future work to experimentally determine the function of these genes in vivo, and how these genes may be involved in microglia/macrophage roles in tissue regeneration.
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Affiliation(s)
- Ousseini Issaka Salia
- Department of Biological Sciences, University of Idaho, Moscow, ID, USA.,Institute for Modeling Collaboration and Innovation (IMCI), University of Idaho, Moscow, ID, USA.,Present affiliation: Kellog Biological Station and Department of Plant Biology, Michigan State University, 3700 East Gull Lake Drive, Hickory Corners, MI, 49060, USA
| | - Diana M Mitchell
- Department of Biological Sciences, University of Idaho, Moscow, ID, USA.
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21
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Long XY, Wang S, Luo ZW, Zhang X, Xu H. Comparison of three administration modes for establishing a zebrafish seizure model induced by N-Methyl-D-aspartic acid. World J Psychiatry 2020; 10:150-161. [PMID: 32844092 PMCID: PMC7418578 DOI: 10.5498/wjp.v10.i7.150] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 04/25/2020] [Accepted: 05/27/2020] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND Epilepsy is a complex neurological disorder characterized by recurrent, unprovoked seizures resulting from the sudden abnormal discharge of brain neurons. It leads to transient brain dysfunction, manifested by abnormal physical movements and consciousness. It can occur at any age, affecting approximately 65 million worldwide, one third of which are still estimated to suffer from refractory seizures. There is an urgent need for further establishment of seizure models in animals, which provides an approach to model epilepsy and could be used to identify novel anti-epileptic therapeutics in the future.
AIM To compare three administration modes for establishing a seizure model caused by N-Methyl-D-aspartic acid (NMDA) in zebrafish.
METHODS Three administration routes of NMDA, including immersion, intravitreal injection and intraperitoneal injection, were compared with regard to their effects on inducing seizure-like behaviors in adult zebrafish. We evaluated neurotoxicity by observing behavioral changes in zebrafish and graded those behaviors with a seizure score. In addition, the protective effects of MK-801 (Dizocilpine) and natural active constituent resveratrol against NMDA-induced alterations were studied.
RESULTS The three NMDA-administration methods triggered different patterns of the epileptic process in adult zebrafish. Seizure scores were increased after increasing NMDA concentration regardless of the mode of administration. However, the curve of immersion continuously rose to a high plateau (after 50 min), while the curves of intravitreal injection and intraperitoneal injection showed a spike in the early stage (10-20 min) followed by a steady decrease in seizure scores. Furthermore, pretreatment with resveratrol and MK-801 significantly delayed seizure onset time and lowered seizure scores.
CONCLUSION By comparing the three methods of administration, intravitreal injection of NMDA was the most suitable for establishing an acute epileptic model in zebrafish. Thus, intraperitoneal injection in zebrafish can be applied to simulate diseases such as epilepsy. In addition, NMDA immersion may be an appropriate method to induce persistent seizures. Moreover, MK-801 and resveratrol showed strong anti-epileptic effects; thus, both of them may be clinically valuable treatments for epilepsy.
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Affiliation(s)
- Xin-Yi Long
- Queen Mary School of Nanchang University, Nanchang 330006, Jiangxi Province, China
| | - Shuang Wang
- Queen Mary School of Nanchang University, Nanchang 330006, Jiangxi Province, China
| | - Zhi-Wen Luo
- Department of Sports Medicine, Huashan Hospital, Fudan University, Shanghai 200433, China
| | - Xu Zhang
- Affiliated Eye Hospital of Nanchang University, Nanchang 330006, Jiangxi Province, China
| | - Hong Xu
- Institute of Life Science, Nanchang University, Nanchang 330031, Jiangxi Province, China
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22
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McGinn TE, Galicia CA, Leoni DC, Partington N, Mitchell DM, Stenkamp DL. Rewiring the Regenerated Zebrafish Retina: Reemergence of Bipolar Neurons and Cone-Bipolar Circuitry Following an Inner Retinal Lesion. Front Cell Dev Biol 2019; 7:95. [PMID: 31245369 PMCID: PMC6562337 DOI: 10.3389/fcell.2019.00095] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Accepted: 05/17/2019] [Indexed: 11/13/2022] Open
Abstract
We previously reported strikingly normal morphologies and functional connectivities of regenerated retinal bipolar neurons (BPs) in zebrafish retinas sampled 60 days after a ouabain-mediated lesion of inner retinal neurons (60 DPI) (McGinn et al., 2018). Here we report early steps in the birth of BPs and formation of their dendritic trees and axonal arbors during regeneration. Adult zebrafish were subjected to ouabain-mediated lesion that destroys inner retinal neurons but spares photoreceptors and Müller glia, and were sampled at 13, 17, and 21 DPI, a timeframe over which plexiform layers reemerge. We show that this timeframe corresponds to reemergence of two populations of BPs (PKCα+ and nyx::mYFP+). Sequential BrdU, EdU incorporation reveals that similar fractions of PKCα+ BPs and HuC/D+ amacrine/ganglion cells are regenerated concurrently, suggesting that the sequence of neuronal production during retinal regeneration does not strictly match that observed during embryonic development. Further, accumulation of regenerated BPs appears protracted, at least through 21 DPI. The existence of isolated, nyx::mYFP+ BPs allowed examination of cytological detail through confocal microscopy, image tracing, morphometric analyses, identification of cone synaptic contacts, and rendering/visualization. Apically-projecting neurites (=dendrites) of regenerated BPs sampled at 13, 17, and 21 DPI are either truncated, or display smaller dendritic trees when compared to controls. In cases where BP dendrites reach the outer plexiform layer (OPL), numbers of dendritic tips are similar to those of controls at all sampling times. Further, by 13-17 DPI, BPs with dendritic tips reaching the outer nuclear layer (ONL) show patterns of photoreceptor connections that are statistically indistinguishable from controls, while those sampled at 21 DPI slightly favor contacts with double cone synaptic terminals over those of blue-sensitive cones. These findings suggest that once regenerated BP dendrites reach the OPL, normal photoreceptor connectomes are established, albeit with some plasticity. Through 17 DPI, some basally-projecting neurites (=axons) of regenerated nyx::mYFP+ BPs traverse long distances, branch into inappropriate layers, or appear to abruptly terminate. These findings suggest that, after a tissue-disrupting lesion, regeneration of inner retinal neurons is a dynamic process that includes ongoing genesis of new neurons and changes in BP morphology.
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Affiliation(s)
- Timothy E McGinn
- Department of Biological Sciences, University of Idaho, Moscow, ID, United States
| | - Carlos A Galicia
- Department of Biological Sciences, University of Idaho, Moscow, ID, United States
| | - Dylan C Leoni
- Department of Biological Sciences, University of Idaho, Moscow, ID, United States
| | - Natalie Partington
- Department of Biology, Brigham Young University-Idaho, Rexburg, ID, United States
| | - Diana M Mitchell
- Department of Biological Sciences, University of Idaho, Moscow, ID, United States
| | - Deborah L Stenkamp
- Department of Biological Sciences, University of Idaho, Moscow, ID, United States
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23
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Mitchell DM, Sun C, Hunter SS, New DD, Stenkamp DL. Regeneration associated transcriptional signature of retinal microglia and macrophages. Sci Rep 2019; 9:4768. [PMID: 30886241 PMCID: PMC6423051 DOI: 10.1038/s41598-019-41298-8] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2018] [Accepted: 03/04/2019] [Indexed: 02/08/2023] Open
Abstract
Zebrafish have the remarkable capacity to regenerate retinal neurons following a variety of damage paradigms. Following initial tissue insult and a period of cell death, a proliferative phase ensues that generates neuronal progenitors, which ultimately regenerate damaged neurons. Recent work has revealed that Müller glia are the source of regenerated neurons in zebrafish. However, the roles of another important class of glia present in the retina, microglia, during this regenerative phase remain elusive. Here, we examine retinal tissue and perform QuantSeq. 3'mRNA sequencing/transcriptome analysis to reveal localization and putative functions, respectively, of mpeg1 expressing cells (microglia/macrophages) during Müller glia-mediated regeneration, corresponding to a time of progenitor proliferation and production of new neurons. Our results indicate that in this regenerative state, mpeg1-expressing cells are located in regions containing regenerative Müller glia and are likely engaged in active vesicle trafficking. Further, mpeg1+ cells congregate at and around the optic nerve head. Our transcriptome analysis reveals several novel genes not previously described in microglia. This dataset represents the first report, to our knowledge, to use RNA sequencing to probe the microglial transcriptome in such context, and therefore provides a resource towards understanding microglia/macrophage function during successful retinal (and central nervous tissue) regeneration.
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Affiliation(s)
- Diana M Mitchell
- Department of Biological Sciences, University of Idaho, Moscow, ID, 83844, USA.
| | - Chi Sun
- Department of Biological Sciences, University of Idaho, Moscow, ID, 83844, USA
- Ophthalmology, Washington University in St. Louis, 4523 Clayton Ave St. Louis, Missouri, 63110, USA
| | - Samuel S Hunter
- Institute for Bioinformatics and Evolutionary Studies, University of Idaho, Moscow, ID, 83844, USA
| | - Daniel D New
- Institute for Bioinformatics and Evolutionary Studies, University of Idaho, Moscow, ID, 83844, USA
| | - Deborah L Stenkamp
- Department of Biological Sciences, University of Idaho, Moscow, ID, 83844, USA
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24
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Beckers A, Moons L. Dendritic shrinkage after injury: a cellular killer or a necessity for axonal regeneration? Neural Regen Res 2019; 14:1313-1316. [PMID: 30860164 PMCID: PMC6524513 DOI: 10.4103/1673-5374.253505] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Dendrites form an essential component of the neuronal circuit have been largely overlooked in regenerative research. Nevertheless, subtle changes in the dendritic arbors of neurons are one of the first stages of various neurodegenerative diseases, leading to dysfunctional neuronal networks and ultimately cellular death. Maintaining dendrites is therefore considered an essential neuroprotective strategy. This mini-review aims to discuss an intriguing hypothesis, which postulates that dendritic shrinkage is an important stimulant to boost axonal regeneration, and thus that preserving dendrites might not be the ideal therapeutic method to regain a full functional network upon central nervous system damage. Indeed, our study in zebrafish, a versatile animal model with robust regenerative capacity recently unraveled that dendritic retraction is evoked prior to axonal regrowth after optic nerve injury. Strikingly, inhibiting dendritic pruning upon damage perturbed axonal regeneration. This constraining effect of dendrites on axonal regrowth has sporadically been proposed in literature, as summarized in this short narrative. In addition, the review discusses a plausible underlying mechanism for the observed antagonistic axon-dendrite interplay, which is based on energy restriction inside neurons. Axonal injury indeed leads to a high local energy demand in which efficient axonal energy supply is fundamental to ensure regrowth. At the same time, axonal lesion is known to induce mitochondrial depolarization, causing energy depletion in the axonal compartment of damaged neurons. Mitochondria, however, become mostly stationary after development, which has been proposed as a potential underlying reason for the low regenerative capacity of adult mammals. Per contra, upon reduced neuronal activity, mitochondrial mobility enhances. In this view, dendritic shrinkage after axonal injury in zebrafish could result in less synaptic input and hence, a release of mitochondria within the soma-dendrite compartment that then translocate to the axonal growth cone to stimulate axonal regeneration. If this hypothesis proofs to be correct, i.e. dendritic remodeling serving as fuel for axonal regeneration, we envision a major shift in the research focus within the neuroregenerative field and in the potential uncovering of various novel therapeutic targets.
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Affiliation(s)
- An Beckers
- Neural Circuit Development and Regeneration Research Group, Department of Biology, KU Leuven, Leuven, Belgium
| | - Lieve Moons
- Neural Circuit Development and Regeneration Research Group, Department of Biology, KU Leuven, Leuven, Belgium
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Angueyra JM, Kindt KS. Leveraging Zebrafish to Study Retinal Degenerations. Front Cell Dev Biol 2018; 6:110. [PMID: 30283779 PMCID: PMC6156122 DOI: 10.3389/fcell.2018.00110] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Accepted: 08/20/2018] [Indexed: 12/11/2022] Open
Abstract
Retinal degenerations are a heterogeneous group of diseases characterized by death of photoreceptors and progressive loss of vision. Retinal degenerations are a major cause of blindness in developed countries (Bourne et al., 2017; De Bode, 2017) and currently have no cure. In this review, we will briefly review the latest advances in therapies for retinal degenerations, highlighting the current barriers to study and develop therapies that promote photoreceptor regeneration in mammals. In light of these barriers, we present zebrafish as a powerful model to study photoreceptor regeneration and their integration into retinal circuits after regeneration. We outline why zebrafish is well suited for these analyses and summarize the powerful tools available in zebrafish that could be used to further uncover the mechanisms underlying photoreceptor regeneration and rewiring. In particular, we highlight that it is critical to understand how rewiring occurs after regeneration and how it differs from development. Insights derived from photoreceptor regeneration and rewiring in zebrafish may provide leverage to develop therapeutic targets to treat retinal degenerations.
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Affiliation(s)
- Juan M. Angueyra
- Retinal Neurophysiology Section, National Eye Institute, National Institutes of Health, Bethesda, MD, United States
| | - Katie S. Kindt
- Section on Sensory Cell Development and Function, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, United States
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DSCAM differentially modulates pre- and postsynaptic structural and functional central connectivity during visual system wiring. Neural Dev 2018; 13:22. [PMID: 30219101 PMCID: PMC6138929 DOI: 10.1186/s13064-018-0118-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Accepted: 08/26/2018] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND Proper patterning of dendritic and axonal arbors is a critical step in the formation of functional neuronal circuits. Developing circuits rely on an array of molecular cues to shape arbor morphology, but the underlying mechanisms guiding the structural formation and interconnectivity of pre- and postsynaptic arbors in real time remain unclear. Here we explore how Down syndrome cell adhesion molecule (DSCAM) differentially shapes the dendritic morphology of central neurons and their presynaptic retinal ganglion cell (RGC) axons in the developing vertebrate visual system. METHODS The cell-autonomous role of DSCAM, in tectal neurons and in RGCs, was examined using targeted single-cell knockdown and overexpression approaches in developing Xenopus laevis tadpoles. Axonal arbors of RGCs and dendritic arbors of tectal neurons were visualized using real-time in vivo confocal microscopy imaging over the course of 3 days. RESULTS In the Xenopus visual system, DSCAM immunoreactivity is present in RGCs, cells in the optic tectum and the tectal neuropil at the time retinotectal synaptic connections are made. Downregulating DSCAM in tectal neurons significantly increased dendritic growth and branching rates while inducing dendrites to take on tortuous paths. Overexpression of DSCAM, in contrast, reduced dendritic branching and growth rate. Functional deficits mediated by tectal DSCAM knockdown were examined using visually guided behavioral assays in swimming tadpoles, revealing irregular behavioral responses to visual stimulus. Functional deficits in visual behavior also corresponded with changes in VGLUT/VGAT expression, markers of excitatory and inhibitory transmission, in the tectum. Conversely, single-cell DSCAM knockdown in the retina revealed that RGC axon arborization at the target is influenced by DSCAM, where axons grew at a slower rate and remained relatively simple. In the retina, dendritic arbors of RGCs were not affected by the reduction of DSCAM expression. CONCLUSIONS Together, our observations implicate DSCAM in the control of both pre- and postsynaptic structural and functional connectivity in the developing retinotectal circuit, where it primarily acts as a neuronal brake to limit and guide postsynaptic dendrite growth of tectal neurons while it also facilitates arborization of presynaptic RGC axons cell autonomously.
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Sun C, Mitchell DM, Stenkamp DL. Isolation of photoreceptors from mature, developing, and regenerated zebrafish retinas, and of microglia/macrophages from regenerating zebrafish retinas. Exp Eye Res 2018; 177:130-144. [PMID: 30096325 DOI: 10.1016/j.exer.2018.08.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Revised: 07/30/2018] [Accepted: 08/06/2018] [Indexed: 12/16/2022]
Abstract
This paper describes experimental procedures for the dissociation of retinal cells of the zebrafish (Danio rerio) for subsequent fluorescence-activated cell sorting (FACS) and gene expression studies. Methods for dissociation of zebrafish retinas followed by FACS and RNA isolation were optimized. This methodology was applied to isolate pure sorted samples of rods, long wavelength-sensitive (LWS) cones, medium wavelength-sensitive (MWS; RH2-2) cones, short wavelength-sensitive (SWS2) cones, and UV-sensitive (SWS1) cones from retinas obtained at selective life-history stages of the zebrafish, and for some of these photoreceptors, following retinal regeneration. We also successfully separated lws1-expressing and lws2-expressing LWS cones from fish of a transgenic line in which lws1 is reported with green fluorescence protein (GFP) and lws2 is reported with red fluorescence protein (RFP). Microglia/macrophages were successfully sorted from regenerating retinas (7 days after a cytotoxic lesion) of a transgenic line in which these immune cells express GFP. Electropherograms verified downstream isolation of high-quality RNA from sorted samples. Examples of post-sorting analysis, as well as results of qRT-PCR studies, validated the purity of sorted populations. For example, qRT-PCR samples derived from isolated Rh2-2 cones contained detectable rh2-2 (opn1mw2) opsin transcripts, but lws opsin transcripts (lws1/opn1lw1, lws2/opn1lw2) were not detected, suggesting that the procedure likely separated double cone pairs. Through this method, pure, sorted cell samples can provide RNA that is reliable for downstream gene expression analyses, such as qRT-PCR and RNA-seq, which may reveal molecular signatures of photoreceptors and microglia for comparative transcriptomics studies.
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Affiliation(s)
- Chi Sun
- Department of Biological Sciences, University of Idaho, Moscow, ID, 83844, USA
| | - Diana M Mitchell
- Department of Biological Sciences, University of Idaho, Moscow, ID, 83844, USA
| | - Deborah L Stenkamp
- Department of Biological Sciences, University of Idaho, Moscow, ID, 83844, USA.
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Mitchell DM, Lovel AG, Stenkamp DL. Dynamic changes in microglial and macrophage characteristics during degeneration and regeneration of the zebrafish retina. J Neuroinflammation 2018; 15:163. [PMID: 29804544 PMCID: PMC5971432 DOI: 10.1186/s12974-018-1185-6] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 04/30/2018] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND In contrast to mammals, zebrafish have the capacity to regenerate retinal neurons following a variety of injuries. Two types of glial cells, Müller glia (MG) and microglia, are known to exist in the zebrafish retina. Recent work has shown that MG give rise to regenerated retinal neurons, but the role of resident microglia, and the innate immune system more generally, during retinal regeneration is not well defined. Specifically, characteristics of the immune system and microglia following substantial neuron death and a successful regenerative response have not been documented. METHODS The neurotoxin ouabain was used to induce a substantial retinal lesion of the inner retina in zebrafish. This lesion results in a regenerative response that largely restores retinal architecture, neuronal morphologies, and connectivities, as well as recovery of visual function. We analyzed cryosections from damaged eyes following immunofluorescence and H&E staining to characterize the initial immune response to the lesion. Whole retinas were analyzed by confocal microscopy to characterize microglia morphology and distribution. Statistical analysis was performed using a two-tailed Student's t test comparing damaged to control samples. RESULTS We find evidence of early leukocyte infiltration to the retina in response to ouabain injection followed by a period of immune cell proliferation that likely includes both resident microglia and substantial numbers of proliferating, extra-retinally derived macrophages, leading to rapid accumulation upon retinal damage. Following immune cell proliferation, Müller glia re-enter the cell cycle. In retinas that have regenerated the layers lost to the initial injury (histologically regenerated), microglia retain morphological features of activation, suggesting ongoing functions that are likely essential to restoration of retinal function. CONCLUSIONS Collectively, these results indicate that microglia and the immune system are dynamic during a successful regenerative response in the retina. This study provides an important framework to probe inflammation in the initiation of, and functional roles of microglia during retinal regeneration.
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Affiliation(s)
- Diana M. Mitchell
- Department of Biological Sciences, University of Idaho, 875 Perimeter Drive, MS 3051, Moscow, ID 83844-3051 USA
| | - Anna G. Lovel
- Department of Biological Sciences, University of Idaho, 875 Perimeter Drive, MS 3051, Moscow, ID 83844-3051 USA
| | - Deborah L. Stenkamp
- Department of Biological Sciences, University of Idaho, 875 Perimeter Drive, MS 3051, Moscow, ID 83844-3051 USA
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Sun C, Galicia C, Stenkamp DL. Transcripts within rod photoreceptors of the Zebrafish retina. BMC Genomics 2018; 19:127. [PMID: 29422031 PMCID: PMC5806438 DOI: 10.1186/s12864-018-4499-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 01/28/2018] [Indexed: 12/03/2022] Open
Abstract
Background The purpose of this study was to identify transcripts of retinal rod photoreceptors of the zebrafish. The zebrafish is an important animal model for vision science due to rapid and tractable development, persistent neurogenesis of rods throughout the lifespan, and capacity for functional retinal regeneration. Results Zebrafish rods, and non-rod retinal cells of the xops:eGFP transgenic line, were separated by cell dissociation and fluorescence-activated cell sorting (FACS), followed by RNA-seq. At a false discovery rate of < 0.01, 597 transcripts were upregulated (“enriched”) in rods vs. other retinal cells, and 1032 were downregulated (“depleted”). Thirteen thousand three hundred twenty four total transcripts were detected in rods, including many not previously known to be expressed by rods. Forty five transcripts were validated by qPCR in FACS-sorted rods vs. other retinal cells. Transcripts enriched in rods from adult retinas were also enriched in rods from larval and juvenile retinas, and were also enriched in rods sorted from retinas subjected to a neurotoxic lesion and allowed to regenerate. Many transcripts enriched in rods were upregulated in retinas of wildtype retinas vs. those of a zebrafish model for rod degeneration. Conclusions We report the generation and validation of an RNA-seq dataset describing the rod transcriptome of the zebrafish, which is now available as a resource for further studies of rod photoreceptor biology and comparative transcriptomics. Electronic supplementary material The online version of this article (10.1186/s12864-018-4499-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Chi Sun
- Department of Biological Sciences, University of Idaho, 875 Perimeter Drive, MS 3051, Moscow, ID, 83844-3051, USA
| | - Carlos Galicia
- Department of Biological Sciences, University of Idaho, 875 Perimeter Drive, MS 3051, Moscow, ID, 83844-3051, USA
| | - Deborah L Stenkamp
- Department of Biological Sciences, University of Idaho, 875 Perimeter Drive, MS 3051, Moscow, ID, 83844-3051, USA.
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