1
|
Goel T, Adams EM, Bialas AL, Tran CM, Rowe T, Martin S, Chandler M, Schubert J, Diamond PH, Collins EMS. Nonlinear elasticity and short-range mechanical coupling govern the rate and symmetry of mouth opening in Hydra. Proc Biol Sci 2024; 291:20232123. [PMID: 38378148 PMCID: PMC10878823 DOI: 10.1098/rspb.2023.2123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Accepted: 01/18/2024] [Indexed: 02/22/2024] Open
Abstract
Hydra has a tubular bilayered epithelial body column with a dome-shaped head on one end and a foot on the other. Hydra lacks a permanent mouth: its head epithelium is sealed. Upon neuronal activation, a mouth opens at the apex of the head which can exceed the body column diameter in seconds, allowing Hydra to ingest prey larger than itself. While the kinematics of mouth opening are well characterized, the underlying mechanism is unknown. We show that Hydra mouth opening is generated by independent local contractions that require tissue-level coordination. We model the head epithelium as an active viscoelastic nonlinear spring network. The model reproduces the size, timescale and symmetry of mouth opening. It shows that radial contractions, travelling inwards from the outer boundary of the head, pull the mouth open. Nonlinear elasticity makes mouth opening larger and faster, contrary to expectations. The model correctly predicts changes in mouth shape in response to external forces. By generating innervated : nerve-free chimera in experiments and simulations, we show that nearest-neighbour mechanical signalling suffices to coordinate mouth opening. Hydra mouth opening shows that in the absence of long-range chemical or neuronal signals, short-range mechanical coupling is sufficient to produce long-range order in tissue deformations.
Collapse
Affiliation(s)
- Tapan Goel
- Department of Physics, University of California San Diego, La Jolla, CA 92093, USA
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
- Department of Biology, University of Maryland, College Park, MD 20742, USA
| | - Ellen M. Adams
- Department of Biology, Swarthmore College, Swarthmore, PA 19081, USA
| | - April L. Bialas
- Department of Biology, Swarthmore College, Swarthmore, PA 19081, USA
| | - Cassidy M. Tran
- Division of Biological Sciences, University of California San Diego, La Jolla, CA 92093, USA
| | - Trevor Rowe
- Department of Physics, University of California San Diego, La Jolla, CA 92093, USA
| | - Sara Martin
- Department of Biology, Swarthmore College, Swarthmore, PA 19081, USA
| | - Maia Chandler
- Department of Biology, Swarthmore College, Swarthmore, PA 19081, USA
| | - Johanna Schubert
- Department of Biology, Swarthmore College, Swarthmore, PA 19081, USA
| | - Patrick H. Diamond
- Department of Physics, University of California San Diego, La Jolla, CA 92093, USA
| | - Eva-Maria S. Collins
- Department of Physics, University of California San Diego, La Jolla, CA 92093, USA
- Department of Biology, Swarthmore College, Swarthmore, PA 19081, USA
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| |
Collapse
|
2
|
Wang R, Bialas AL, Goel T, Collins EMS. Mechano-Chemical Coupling in Hydra Regeneration and Patterning. Integr Comp Biol 2023; 63:1422-1441. [PMID: 37339912 DOI: 10.1093/icb/icad070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 06/07/2023] [Accepted: 06/12/2023] [Indexed: 06/22/2023] Open
Abstract
The freshwater cnidarian Hydra can regenerate from wounds, small tissue fragments and even from aggregated cells. This process requires the de novo development of a body axis and oral-aboral polarity, a fundamental developmental process that involves chemical patterning and mechanical shape changes. Gierer and Meinhardt recognized that Hydra's simple body plan and amenability to in vivo experiments make it an experimentally and mathematically tractable model to study developmental patterning and symmetry breaking. They developed a reaction-diffusion model, involving a short-range activator and a long-range inhibitor, which successfully explained patterning in the adult animal. In 2011, HyWnt3 was identified as a candidate for the activator. However, despite the continued efforts of both physicists and biologists, the predicted inhibitor remains elusive. Furthermore, the Gierer-Meinhardt model cannot explain de novo axis formation in cellular aggregates that lack inherited tissue polarity. The aim of this review is to synthesize the current knowledge on Hydra symmetry breaking and patterning. We summarize the history of patterning studies and insights from recent biomechanical and molecular studies, and highlight the need for continued validation of theoretical assumptions and collaboration across disciplinary boundaries. We conclude by proposing new experiments to test current mechano-chemical coupling models and suggest ideas for expanding the Gierer-Meinhardt model to explain de novo patterning, as observed in Hydra aggregates. The availability of a fully sequenced genome, transgenic fluorescent reporter strains, and modern imaging techniques, that enable unprecedented observation of cellular events in vivo, promise to allow the community to crack Hydra's secret to patterning.
Collapse
Affiliation(s)
- Rui Wang
- Department of Bioengineering, University of California San Diego, 9500 Gilman Drive, La Jolla, 92093 CA, USA
| | - April L Bialas
- Department of Biology, Swarthmore College, 500 College Ave, Swarthmore, 19081 PA, USA
| | - Tapan Goel
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, 30332 GA, USA
- Department of Physics, University of California San Diego, 9500 Gilman Drive, La Jolla, 92093 CA, USA
| | - Eva-Maria S Collins
- Department of Biology, Swarthmore College, 500 College Ave, Swarthmore, 19081 PA, USA
- Department of Physics, University of California San Diego, 9500 Gilman Drive, La Jolla, 92093 CA, USA
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, 19104 PA, USA
| |
Collapse
|
3
|
Goel T, Ireland D, Shetty V, Rabeler C, Diamond PH, Collins EMS. Corrigendum: Let it rip: the mechanics of self-bisection in asexual planarians determines their population reproductive strategies (2022 Phys. Biol.
19 016002). Phys Biol 2022; 19. [DOI: 10.1088/1478-3975/ac97d7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 10/05/2022] [Indexed: 11/11/2022]
|
4
|
Goel T, Ireland D, Shetty V, Rabeler C, Diamond PH, Collins EMS. Let it rip: the mechanics of self-bisection in asexual planarians determines their population reproductive strategies. Phys Biol 2021; 19. [PMID: 34638110 DOI: 10.1088/1478-3975/ac2f29] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 10/12/2021] [Indexed: 11/11/2022]
Abstract
Asexual freshwater planarians reproduce by transverse bisection (binary fission) into two pieces. This process produces a head and a tail, which fully regenerate within 1-2 weeks. How planarians split into two offspring-using only their musculature and substrate traction-is a challenging biomechanics problem. We found that three different species,Dugesia japonica,Girardia tigrinaandSchmidtea mediterranea, have evolved three different mechanical solutions to self-bisect. Using time lapse imaging of the fission process, we quantitatively characterize the main steps of division in the three species and extract the distinct and shared key features. Across the three species, planarians actively alter their body shape, regulate substrate traction, and use their muscles to generate tensile stresses large enough to overcome the ultimate tensile strength of the tissue. Moreover, we show thathoweach planarian species divides dictates how resources are split among its offspring. This ultimately determines offspring survival and reproductive success. Thus, heterospecific differences in the mechanics of self-bisection of individual worms explain the observed differences in the population reproductive strategies of different planarian species.
Collapse
Affiliation(s)
- Tapan Goel
- Physics Department, UC San Diego, La Jolla, CA, United States of America
| | - Danielle Ireland
- Biology Department, Swarthmore College, Swarthmore, PA, United States of America
| | - Vir Shetty
- Physics and Astronomy Department, Swarthmore College, Swarthmore, PA, United States of America
| | - Christina Rabeler
- Biology Department, Swarthmore College, Swarthmore, PA, United States of America
| | - Patrick H Diamond
- Physics Department, UC San Diego, La Jolla, CA, United States of America
| | - Eva-Maria S Collins
- Physics Department, UC San Diego, La Jolla, CA, United States of America.,Biology Department, Swarthmore College, Swarthmore, PA, United States of America.,Physics and Astronomy Department, Swarthmore College, Swarthmore, PA, United States of America
| |
Collapse
|
5
|
Abstract
The ability to make transgenic Hydra lines has allowed for quantitative in vivo studies of Hydra regeneration and physiology. These studies commonly include excision, grafting and transplantation experiments along with high-resolution imaging of live animals, which can be challenging due to the animal’s response to touch and light stimuli. While various anesthetics have been used in Hydra studies, they tend to be toxic over the course of a few hours or their long-term effects on animal health are unknown. Here, we show that the monoterpenoid alcohol linalool is a useful anesthetic for Hydra. Linalool is easy to use, non-toxic, fast acting, and reversible. It has no detectable long-term effects on cell viability or cell proliferation. We demonstrate that the same animal can be immobilized in linalool multiple times at intervals of several hours for repeated imaging over 2–3 days. This uniquely allows for in vivo imaging of dynamic processes such as head regeneration. We directly compare linalool to currently used anesthetics and show its superior performance. Linalool will be a useful tool for tissue manipulation and imaging in Hydra research in both research and teaching contexts.
Collapse
Affiliation(s)
- Tapan Goel
- Department of Physics, University of California San Diego, La Jolla, CA, United States of America
- Department of Biology, Swarthmore College, Swarthmore, PA, United States of America
| | - Rui Wang
- Department of Biology, Swarthmore College, Swarthmore, PA, United States of America
- Department of Bioengineering, University of California San Diego, La Jolla, CA, United States of America
| | - Sara Martin
- Department of Biology, Swarthmore College, Swarthmore, PA, United States of America
| | - Elizabeth Lanphear
- Department of Biology, Swarthmore College, Swarthmore, PA, United States of America
| | - Eva-Maria S. Collins
- Department of Physics, University of California San Diego, La Jolla, CA, United States of America
- Department of Biology, Swarthmore College, Swarthmore, PA, United States of America
- * E-mail:
| |
Collapse
|
6
|
Wang R, Goel T, Khazoyan K, Sabry Z, Quan HJ, Diamond PH, Collins EMS. Mouth Function Determines the Shape Oscillation Pattern in Regenerating Hydra Tissue Spheres. Biophys J 2019; 117:1145-1155. [PMID: 31443907 DOI: 10.1016/j.bpj.2019.07.051] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 06/25/2019] [Accepted: 07/30/2019] [Indexed: 12/12/2022] Open
Abstract
Hydra is a small freshwater polyp capable of regeneration from small tissue pieces and from aggregates of cells. During regeneration, a hollow bilayered sphere is formed that undergoes osmotically driven shape oscillations of inflation and rupture. These oscillations are necessary for successful regeneration. Eventually, the oscillating sphere breaks rotational symmetry along the future head-foot axis of the animal. Notably, the shape oscillations show an abrupt shift from large-amplitude, long-period oscillations to small-amplitude, short-period oscillations. It has been widely accepted that this shift in oscillation pattern is linked to symmetry breaking and axis formation, and current theoretical models of Hydra symmetry breaking use this assumption as a model constraint. However, a mechanistic explanation for the shift in oscillation pattern is lacking. Using in vivo manipulation and imaging, we quantified the shape oscillation dynamics and dissected the timing and triggers of the pattern shift. Our experiments demonstrate that the shift in the shape oscillation pattern in regenerating Hydra tissue pieces is caused by the formation of a functional mouth and not by shape symmetry breaking as previously assumed. Thus, model assumptions must be revised in light of these new experimental data, which can be used to constrain and validate improved theoretical models of pattern formation in Hydra.
Collapse
Affiliation(s)
- Rui Wang
- Department of Bioengineering, University of California San Diego, La Jolla, California; Biology Department, Swarthmore College, Swarthmore, Pennsylvania
| | - Tapan Goel
- Department of Physics, University of California San Diego, La Jolla, California; Biology Department, Swarthmore College, Swarthmore, Pennsylvania
| | - Kate Khazoyan
- Department of Bioengineering, University of California San Diego, La Jolla, California
| | - Ziad Sabry
- Biology Department, Swarthmore College, Swarthmore, Pennsylvania
| | - Heng J Quan
- Department of Physics, University of California San Diego, La Jolla, California; Department of Mathematics, University of California San Diego, La Jolla, California
| | - Patrick H Diamond
- Department of Physics, University of California San Diego, La Jolla, California
| | - Eva-Maria S Collins
- Department of Physics, University of California San Diego, La Jolla, California; Biology Department, Swarthmore College, Swarthmore, Pennsylvania.
| |
Collapse
|
7
|
Goel T, Sharma J, Mahey R, Kachhawa G, Kriplani I, Kriplani A. Effect of Anti Tubercular Treatment on Laparoscopic Obstetrics and gynecology department at a hospital and Hysteroscopic Findings in Infertile Women with Genital Tuberculosis. J Minim Invasive Gynecol 2018. [DOI: 10.1016/j.jmig.2018.09.695] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
8
|
Mahey R, Goel T, Gupta M, Kachhawa G, Kriplani A. To evaluate the pregnancy rate after endometrial scratching in couples with unexplained infertility in ovulation induction and IUI cycles. Fertil Steril 2015. [DOI: 10.1016/j.fertnstert.2015.07.1068] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
9
|
Abstract
Rupture of the triceps tendon is an uncommon injury, probably the rarest of all tendinous ruptures. We present a case of missed diagnosis of triceps tendon rupture. Such diagnosis should be considered when a patient presents with pain and swelling at the back of the elbow after a fall on an outstretched hand.
Collapse
Affiliation(s)
- S C Sharma
- Department of Orthopaedics, Paraplegia and Rehabilitation, Pt BD Sharma PGIMS, Rohtak (Haryana), India
| | | | | | | |
Collapse
|
10
|
Welling RE, Taha A, Goel T, Cranley J, Krause R, Hafner C, Tew J. Extracranial carotid artery aneurysms. Surgery 1983; 93:319-23. [PMID: 6687412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Carotid artery aneurysms are rare, however, serious complications may result--namely, rupture, thrombosis, or emboli. Five distinct clinical types of aneurysms are reported with different symptoms and treatment. Fusiform, saccular, false, and mycotic aneurysms are best treated with interposition autogenous vein grafting. Spontaneous dissection aneurysms are best treated initially with anticoagulation and follow-up angiography. Recanalization is the usual result. Meticulous surgical technique to prevent perioperative emboli is essential to prevent central nervous system complications.
Collapse
|