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Boggs TE, Gross JB. Gill morphology adapted to oxygen-limited caves in Astyanax mexicanus. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART A, ECOLOGICAL AND INTEGRATIVE PHYSIOLOGY 2024. [PMID: 39031584 DOI: 10.1002/jez.2840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2024] [Revised: 05/20/2024] [Accepted: 05/23/2024] [Indexed: 07/22/2024]
Abstract
Sensing and acquiring dissolved oxygen is crucial for nearly all aquatic life. This may become even more vital as dissolved oxygen concentrations continue to decline in many aquatic environments. While certain phenotypes that enable fish to live in low oxygen have been characterized, adaptations that arise following sudden, drastic reductions in dissolved oxygen are relatively unknown. Here, we assessed the blind Mexican cavefish, Astyanax mexicanus, for alterations to gill morphology that may be adaptive for life in hypoxic caves. The Astyanax system provides the unique opportunity to compare gill morphology between stereotypical "surface" adapted morphotypes and obligate cave-dwelling conspecifics. While the surface environment is well-oxygenated, cavefish must cope with significantly reduced oxygen. We began by quantifying traditional morphological gill traits including filament number and length as well as lamellar density and height in surface fish and two distinct cave populations, Pachón and Tinaja. This enabled us to estimate total lamellar height, a proxy for gill surface area. We then used immunohistochemical staining to label 5-HT-positive neuroepithelial cells (NECs), which serve as key oxygen sensors in fish. We discovered an increase in gill surface area for both cavefish populations compared to surface, which may enable a higher capacity of oxygen acquisition. Additionally, we found more NECs in Pachón cavefish compared to both surface fish and Tinaja cavefish, suggesting certain selective pressures may be cave-specific. Collectively, this work provides evidence that cavefish have adapted to low oxygen conditions via alterations to gill morphology and oxygen sensing, and informs evolutionary mechanisms of rapid adaptation to dramatic, chronic hypoxia.
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Affiliation(s)
- Tyler E Boggs
- Department of Biological Sciences, University of Cincinnati, Cincinnati, Ohio, USA
| | - Joshua B Gross
- Department of Biological Sciences, University of Cincinnati, Cincinnati, Ohio, USA
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2
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Biswas T, Rajendran N, Hassan H, Li H, Zhao C, Rohner N. 3D spheroid culturing of Astyanax mexicanus liver-derived cell lines recapitulates distinct transcriptomic and metabolic states of in vivo tissue environment. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART B, MOLECULAR AND DEVELOPMENTAL EVOLUTION 2024; 342:301-312. [PMID: 38192038 PMCID: PMC11060904 DOI: 10.1002/jez.b.23236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Revised: 10/26/2023] [Accepted: 12/23/2023] [Indexed: 01/10/2024]
Abstract
In vitro assays are crucial tools for gaining detailed insights into various biological processes, including metabolism. Cave morphs of the river-dwelling fish species, Astyanax mexicanus, have adapted their metabolism allowing them to thrive in the biodiversity-deprived and nutrient-limited environment of caves. Liver-derived cells from the cave and river morphs of A. mexicanus have proven to be excellent in vitro resources to better understand the unique metabolism of these fish. However, the current 2D cultures have not fully captured the complex metabolic profile of the Astyanax liver. It is known that 3D culturing can modulate the transcriptomic state of cells when compared to its 2D monolayer culture. Therefore, to broaden the possibilities of the in vitro system by modeling a wider gamut of metabolic pathways, we cultured the liver-derived Astyanax cells of both surface and cavefish into 3D spheroids. We successfully established 3D cultures at various cell seeding densities for several weeks and characterized the resultant transcriptomic and metabolic variations. We found that the 3D cultured Astyanax cells exhibit an altered transcriptomic profile and consequently represent a wider range of metabolic pathways, including cell cycle changes and antioxidant activities, associated with liver functioning as compared to its monolayer culture. Enzymatic assay measuring antioxidants in 2D culture and 3D spheroids also revealed enhanced antioxidative capacity of 3D cultured spheroids, in line with the differential gene expression data. Additionally, the spheroids also exhibited surface and cave-specific metabolic signatures, making it a suitable system for evolutionary studies associated with cave adaptation. Notably, cavefish derived spheroids enriched for genes responding to xenobiotic stimulus, while the ones from surface enriched for immune response, both of which resonated with known physiologically adaptations associated with each morph. Taken together, the liver-derived spheroids prove to be a promising in vitro model for widening our understanding of metabolism in A. mexicanus and of vertebrates in general.
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Affiliation(s)
- Tathagata Biswas
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Naresh Rajendran
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Huzaifa Hassan
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Hua Li
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Chongbei Zhao
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Nicolas Rohner
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
- Department of Cell Biology & Physiology, University of Kansas Medical Center, Kansas City, KS 66103, USA
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Lloyd E, Xia F, Moore K, Zertuche C, Rastogi A, Kozol R, Kenzior O, Warren W, Appelbaum L, Moran RL, Zhao C, Duboue E, Rohner N, Keene AC. Elevated DNA Damage without signs of aging in the short-sleeping Mexican Cavefish. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.18.590174. [PMID: 38659770 PMCID: PMC11042282 DOI: 10.1101/2024.04.18.590174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
Dysregulation of sleep has widespread health consequences and represents an enormous health burden. Short-sleeping individuals are predisposed to the effects of neurodegeneration, suggesting a critical role for sleep in the maintenance of neuronal health. While the effects of sleep on cellular function are not completely understood, growing evidence has identified an association between sleep loss and DNA damage, raising the possibility that sleep facilitates efficient DNA repair. The Mexican tetra fish, Astyanax mexicanus provides a model to investigate the evolutionary basis for changes in sleep and the consequences of sleep loss. Multiple cave-adapted populations of these fish have evolved to sleep for substantially less time compared to surface populations of the same species without identifiable impacts on healthspan or longevity. To investigate whether the evolved sleep loss is associated with DNA damage and cellular stress, we compared the DNA Damage Response (DDR) and oxidative stress levels between A. mexicanus populations. We measured markers of chronic sleep loss and discovered elevated levels of the DNA damage marker γH2AX in the brain, and increased oxidative stress in the gut of cavefish, consistent with chronic sleep deprivation. Notably, we found that acute UV-induced DNA damage elicited an increase in sleep in surface fish but not in cavefish. On a transcriptional level, only the surface fish activated the photoreactivation repair pathway following UV damage. These findings suggest a reduction of the DDR in cavefish compared to surface fish that coincides with elevated DNA damage in cavefish. To examine DDR pathways at a cellular level, we created an embryonic fibroblast cell line from the two populations of A. mexicanus. We observed that both the DDR and DNA repair were diminished in the cavefish cells, corroborating the in vivo findings and suggesting that the acute response to DNA damage is lost in cavefish. To investigate the long-term impact of these changes, we compared the transcriptome in the brain and gut of aged surface fish and cavefish. Strikingly, many genes that are differentially expressed between young and old surface fish do not transcriptionally vary by age in cavefish. Taken together, these findings suggest that have developed resilience to sleep loss, despite possessing cellular hallmarks of chronic sleep deprivation.
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Affiliation(s)
- Evan Lloyd
- Department of Biology, Texas A&M University, College Station, TX 77840
| | - Fanning Xia
- Stowers Institute for Medical Research, Kansas City, MO 64110
| | - Kinsley Moore
- Department of Biology, Texas A&M University, College Station, TX 77840
| | - Carolina Zertuche
- Department of Biology, Texas A&M University, College Station, TX 77840
| | - Aakriti Rastogi
- Department of Biology, Texas A&M University, College Station, TX 77840
| | - Rob Kozol
- Harriet Wilkes Honors College, Florida Atlantic University, Jupiter, FL 33458
| | - Olga Kenzior
- Stowers Institute for Medical Research, Kansas City, MO 64110
| | - Wesley Warren
- Department of Genomics, University of Missouri, Columbia, MO 65211
| | - Lior Appelbaum
- Faculty of Life Science and the Multidisciplinary Brain Research Center, Bar Illan University, Ramat Gan, Israel
| | - Rachel L Moran
- Department of Biology, Texas A&M University, College Station, TX 77840
| | - Chongbei Zhao
- Stowers Institute for Medical Research, Kansas City, MO 64110
| | - Erik Duboue
- Harriet Wilkes Honors College, Florida Atlantic University, Jupiter, FL 33458
| | - Nicolas Rohner
- Stowers Institute for Medical Research, Kansas City, MO 64110
| | - Alex C Keene
- Department of Biology, Texas A&M University, College Station, TX 77840
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Jiménez AG, Nash-Braun E, Meyers JR. White epaxial muscle aerobic and anaerobic potential and muscle fiber structure in surface and cave morphotypes of the Mexican cavefish (Astyanax mexicanus). JOURNAL OF EXPERIMENTAL ZOOLOGY. PART A, ECOLOGICAL AND INTEGRATIVE PHYSIOLOGY 2023; 339:861-868. [PMID: 37493010 DOI: 10.1002/jez.2736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Revised: 07/07/2023] [Accepted: 07/10/2023] [Indexed: 07/27/2023]
Abstract
Proper muscle function and muscle fiber structures that match the environmental demands of organisms are imperative to their success in any ecosystem. The Mexican cavefish, Astyanax mexicanus, has two morphotypes: an obligate cave-dwelling form that lives in thermally insulated caves and an O2 poor environment, and a surface form that lives in a more thermally variable, but O2 rich river environment. As environment can determine physiological adaptations, it is of interest to compare the aerobic and anaerobic metabolic profiles of white muscle metabolism in both morphotypes of this species, as well as their muscle structures. Here, we used white muscle of both morphotypes of the Mexican cavefish to determine citrate synthase (CS) activity as a measure of aerobic potential, and lactate concentration as a measure of anaerobic potential at three different chronic acclimation temperatures (14°C, 25°C, and 31°C). By examining aerobic and anaerobic potential in both morphs, we sought to link environmental thermal flexibility to muscle metabolism. We found that the surface morphotype had higher CS activity and lower lactate concentration, suggesting an overall more efficient usage of aerobic metabolism; whereas the cave morphotype showed lower CS activity and higher lactate concentration, suggesting a stronger reliance on anaerobic pathways. We also measured white muscle histological variables that have been previously linked to whole-animal metabolism: fiber diameter, number of nuclei per mm of fiber and myonuclear domain (MND) of both morphotypes at 25°C to examine cell-level differences in muscle morphology. However, we found no differences in fiber diameter, number of nuclei per mm of fiber or MND between the two morphotypes. Thus, although the cellular morphology is similar in these species, the environmental differences in the evolution of the two morphs has led to differences in their metabolic profiles.
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Affiliation(s)
| | - Evan Nash-Braun
- Department of Biology, Colgate University, Hamilton, New York, USA
| | - Jason R Meyers
- Department of Biology, Colgate University, Hamilton, New York, USA
- Neuroscience Program, Colgate University, Hamilton, New York, USA
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5
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Rohner N. The cavefish Astyanax mexicanus. Nat Methods 2023; 20:948-950. [PMID: 37434002 DOI: 10.1038/s41592-023-01916-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/13/2023]
Affiliation(s)
- Nicolas Rohner
- Stowers Institute for Medical Research, Kansas City, MO, USA.
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Biswas T, Rajendran N, Hassan H, Zhao C, Rohner N. 3D spheroid culturing of Astyanax mexicanus liver-derived cell lines recapitulates distinct transcriptomic and metabolic states of in vivo tissue environment. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.09.544423. [PMID: 37333136 PMCID: PMC10274882 DOI: 10.1101/2023.06.09.544423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
In vitro assays are crucial tools for gaining detailed insights into various biological processes, including metabolism. Cave morphs of the river-dwelling fish species, Astyanax mexicanus, have adapted their metabolism allowing them to thrive in the biodiversity-deprived and nutrient-limited environment of caves. Liver-derived cells from the cave and river morphs of Astyanax mexicanus have proven to be excellent in vitro resources to better understand the unique metabolism of these fish. However, the current 2D cultures have not fully captured the complex metabolic profile of the Astyanax liver. It is known that 3D culturing can modulate the transcriptomic state of cells when compared to its 2D monolayer culture. Therefore, in order to broaden the possibilities of the in vitro system by modeling a wider gamut of metabolic pathways, we cultured the liver-derived Astyanax cells of both surface and cavefish into 3D spheroids. We successfully established 3D cultures at various cell seeding densities for several weeks and characterized the resultant transcriptomic and metabolic variations. We found that the 3D cultured Astyanax cells represent a wider range of metabolic pathways, including cell cycle changes and antioxidant activities, associated with liver functioning as compared to its monolayer culture. Additionally, the spheroids also exhibited surface and cave-specific metabolic signatures, making it a suitable system for evolutionary studies associated with cave adaptation. Taken together, the liver-derived spheroids prove to be a promising in vitro model for widening our understanding of metabolism in Astyanax mexicanus and of vertebrates in general.
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Affiliation(s)
- Tathagata Biswas
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Naresh Rajendran
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Huzaifa Hassan
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Chongbei Zhao
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Nicolas Rohner
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
- Department of Cell Biology & Physiology, University of Kansas Medical Center, Kansas City, KS 66103, USA
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Zhao C. Cell culture: in vitro model system and a promising path to in vivo applications. J Histotechnol 2023; 46:1-4. [PMID: 36691848 DOI: 10.1080/01478885.2023.2170772] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Chongbei Zhao
- Stowers Institute for Medical Research, Kansas City, MO, USA
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Olsen L, Levy M, Medley JK, Hassan H, Miller B, Alexander R, Wilcock E, Yi K, Florens L, Weaver K, McKinney SA, Peuß R, Persons J, Kenzior A, Maldonado E, Delventhal K, Gluesenkamp A, Mager E, Coughlin D, Rohner N. Metabolic reprogramming underlies cavefish muscular endurance despite loss of muscle mass and contractility. Proc Natl Acad Sci U S A 2023; 120:e2204427120. [PMID: 36693105 PMCID: PMC9945943 DOI: 10.1073/pnas.2204427120] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2022] [Accepted: 11/15/2022] [Indexed: 01/25/2023] Open
Abstract
Physical inactivity is a scourge to human health, promoting metabolic disease and muscle wasting. Interestingly, multiple ecological niches have relaxed investment into physical activity, providing an evolutionary perspective into the effect of adaptive physical inactivity on tissue homeostasis. One such example, the Mexican cavefish Astyanax mexicanus, has lost moderate-to-vigorous activity following cave colonization, reaching basal swim speeds ~3.7-fold slower than their river-dwelling counterpart. This change in behavior is accompanied by a marked shift in body composition, decreasing total muscle mass and increasing fat mass. This shift persisted at the single muscle fiber level via increased lipid and sugar accumulation at the expense of myofibrillar volume. Transcriptomic analysis of laboratory-reared and wild-caught cavefish indicated that this shift is driven by increased expression of pparγ-the master regulator of adipogenesis-with a simultaneous decrease in fast myosin heavy chain expression. Ex vivo and in vivo analysis confirmed that these investment strategies come with a functional trade-off, decreasing cavefish muscle fiber shortening velocity, time to maximal force, and ultimately maximal swimming speed. Despite this, cavefish displayed a striking degree of muscular endurance, reaching maximal swim speeds ~3.5-fold faster than their basal swim speeds. Multi-omic analysis suggested metabolic reprogramming, specifically phosphorylation of Pgm1-Threonine 19, as a key component enhancing cavefish glycogen metabolism and sustained muscle contraction. Collectively, we reveal broad skeletal muscle changes following cave colonization, displaying an adaptive skeletal muscle phenotype reminiscent to mammalian disuse and high-fat models while simultaneously maintaining a unique capacity for sustained muscle contraction via enhanced glycogen metabolism.
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Affiliation(s)
- Luke Olsen
- Stowers Institute for Medical Research, Kansas City, MO64110
- Department of Cell Biology and Physiology, University of Kansas Medical Center, Kansas City, KS66160
| | - Michaella Levy
- Stowers Institute for Medical Research, Kansas City, MO64110
| | - J. Kyle Medley
- Stowers Institute for Medical Research, Kansas City, MO64110
| | - Huzaifa Hassan
- Stowers Institute for Medical Research, Kansas City, MO64110
| | - Brandon Miller
- Stowers Institute for Medical Research, Kansas City, MO64110
| | | | - Emma Wilcock
- Department of Biology, Widener University, Chester, PA19013
| | - Kexi Yi
- Stowers Institute for Medical Research, Kansas City, MO64110
| | | | - Kyle Weaver
- Stowers Institute for Medical Research, Kansas City, MO64110
| | | | - Robert Peuß
- Institute for Evolution and Biodiversity, University of Münster, Münster48149, Germany
| | - Jenna Persons
- Stowers Institute for Medical Research, Kansas City, MO64110
| | | | - Ernesto Maldonado
- EvoDevo Research Group, Unidad Académica de Sistemas Arrecifales, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Puerto Morelos, Quintana Roo77580, Mexico
| | - Kym Delventhal
- Stowers Institute for Medical Research, Kansas City, MO64110
| | - Andrew Gluesenkamp
- Center for Conservation and Research, San Antonio Zoo, San Antonio, TX78212
| | - Edward Mager
- Department of Biological Sciences, Advanced Environmental Research Institute, University of North Texas, Denton, TX76203
| | - David Coughlin
- Department of Biology, Widener University, Chester, PA19013
| | - Nicolas Rohner
- Stowers Institute for Medical Research, Kansas City, MO64110
- Department of Cell Biology and Physiology, University of Kansas Medical Center, Kansas City, KS66160
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