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Alsafy MAM, El-Sharnobey NKA, El-Gendy SAA, Abumandour MA, Ez Elarab SM, Rashwan AM, Hanafy BG. Macroscopic, microscopic, and immunofluorescent characterization of the Greek tortoise (Testudo graeca graeca) oropharyngeal floor with concern to its feed adaptation as a herbivorous land reptile. Microsc Res Tech 2024. [PMID: 38808586 DOI: 10.1002/jemt.24619] [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: 03/21/2024] [Revised: 05/07/2024] [Accepted: 05/17/2024] [Indexed: 05/30/2024]
Abstract
The current investigation focuses on gross anatomy, light, and scanning electron microscopy (SEM) of the Testudo graeca oropharyngeal floor, with particular reference to the immunofluorescence technique to examine its tongue. The T. graeca oropharyngeal floor showed many anatomical structures: the lower rhamphotheca, paralingual ridge, lower alveolar ridge, tongue, laryngeal mound, and glottis. The lower rhamphotheca appeared as a V-shaped jaw line with a highly serrated edge and a median tomium (beak). SEM observations of the lingual apex and the lingual body showed rectangular and conical filiform papillae with porous surfaces and taste pores. Meanwhile, the lingual root had two wings that carried papillae with different shapes: dagger-shaped, conical, bifurcated, and leaf-like papillae, and these papillae lacked taste pores. The laryngeal mound had openings for the laryngeal mucus gland and its secretions. Light microscopy findings showed mucous glands in the propria submucosa and near the mucosal surface of the lingual apex. The lingual root had lingual papillae and two hyaline cartilaginous skeletons between skeletal muscles, and the lingual papillae were elongated filiform, rectangular filiform papillae, and fungiform papillae. The lamina propria constituted the core of the lingual papillae and the mucous gland, they had a positive reaction with the periodic acid schiff (PAS) reagent. The apical surface of the fungiform papillae had taste pores. Under immunofluorescence, the vimentin was detected in taste bud cells, and synaptophysin reacted to the taste buds and nerve bundles. The current study of the Greek tortoise oropharyngeal floor investigated its herbivorous eating habits using its serrated lower rhamphotheca, a large tongue with differently shaped papillae, and numerous mucous glands. RESEARCH HIGHLIGHTS: The Greek tortoise (T. graeca graeca) oropharyngeal floor showed many anatomical structures: lower rhamphotheca, paralingual ridge, lower alveolar ridge, tongue, laryngeal mound, and glottis. SEM and light microscopy observations of the tongue revealed varied types and shapes of lingual papillae with a porous surface on the tongue apex (rectangular or conical filiform papillae), on the tongue body (filiform and fungiform papillae), and on the tongue root (dagger-shaped, conical, bifurcated, and leaf-like papillae). Light microscopy findings: the lamina propria constituted the core of the lingual papillae and had numerous mucous glands that had a slightly magenta-red color with PAS reagent. The apical surface of the fungiform papillae had taste pores. Vimentin and synaptophysin gave a reaction to the taste buds.
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Affiliation(s)
- Mohamed A M Alsafy
- Department of Anatomy and Embryology, Faculty of Veterinary Medicine, Alexandria University, Alexandria, Egypt
| | - Nermin K A El-Sharnobey
- Department of Anatomy and Embryology, Faculty of Veterinary Medicine, Alexandria University, Alexandria, Egypt
| | - Samir A A El-Gendy
- Department of Anatomy and Embryology, Faculty of Veterinary Medicine, Alexandria University, Alexandria, Egypt
| | - Mohamed A Abumandour
- Department of Anatomy and Embryology, Faculty of Veterinary Medicine, Alexandria University, Alexandria, Egypt
| | - Samar M Ez Elarab
- Department of Histology and Cytology, Faculty of Veterinary Medicine, Alexandria University, Alexandria, Egypt
| | - Ahmed M Rashwan
- Department of Anatomy and Embryology, Faculty of Veterinary Medicine, Damanhour University, Damanhour, Egypt
- Laboratory of Life Science Frontiers, Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan
| | - Basma G Hanafy
- Department of Anatomy and Embryology, Faculty of Veterinary Medicine, Alexandria University, Alexandria, Egypt
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Oliveira REMD, Attademo FLN, Sousa ACFCD, Magalhães MDS, Oliveira RMD, de Moura CEB, Silva AR, Pereira AF, Fragoso ABL, Silva FJDL, Oliveira MFD. Oropharyngeal cavity floor morphology in Eretmochelys imbricata (Testudines: Cheloniidae) hatchlings and evolutionary implications. Anat Rec (Hoboken) 2023; 306:343-353. [PMID: 36054069 DOI: 10.1002/ar.25061] [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] [Received: 03/05/2022] [Revised: 08/15/2022] [Accepted: 08/17/2022] [Indexed: 01/25/2023]
Abstract
Morphological studies of the oropharyngeal cavity of chelonians have become an interesting tool in the understanding of evolutionary processes associated with feeding habits in aquatic animals and the transition from aquatic to terrestrial forms. In this context, the aim of the present study was to describe the oropharyngeal cavity floor morphology of hawksbill sea turtle (Eretmochelys imbricata) hatchlings. Ten dead hatchlings of undefined sex were obtained from nests hatched on the coast of the state of Rio Grande do Norte, Brazil. The heads of each specimen were fixed, dissected, and analyzed at the macroscopic and microscopic levels. The oropharyngeal cavity floor of the hawksbill sea turtle hatchlings is formed by the tongue, pharynx, floor muscles, and hyolingual skeleton, delimited in the rostral and lateral directions by a keratinized beak, called the rhamphotheca, and in the caudal region at the limit between the pharynx and the esophagus. The tongue muscles and the muscles that support the floor of the oral cavity comprise the following: m. hypoglossohyoideus, m. hypoglossoglossus, m. hyoglossus, m. genioglossus, m. constrictor laryngis, m. geniohyoideus pars lateralis, and m. intermandibularis. The oropharyngeal cavity floor mucosa is formed by keratinized stratified squamous epithelium and the lamina propria is formed by loose connective tissue. The floor mucosa is devoid of taste buds. We believe that the basic oropharyngeal cavity floor characteristics in hawksbill sea turtle hatchlings may comprise indications that these animals are plesiomorphic and that semiaquatic and terrestrial turtles may have undergone adaptations to feed out of water.
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Affiliation(s)
- Radan Elvis Matias de Oliveira
- Programa de Pós-Graduação em Ciência Animal (PPGCA), Universidade Federal Rural do Semi-Árido (UFERSA), Mossoró, Rio Grande do Norte, Brazil.,Centro de Estudos e Monitoramento Ambiental (CEMAM), Areia Branca, Rio Grande do Norte, Brazil.,Projeto Cetáceos da Costa Branca (PCCB), Universidade do Estado do Rio Grande do Norte (UERN), Mossoró, Rio Grande do Norte, Brazil
| | - Fernanda Loffler Niemeyer Attademo
- Centro de Estudos e Monitoramento Ambiental (CEMAM), Areia Branca, Rio Grande do Norte, Brazil.,Centro Universitário Internacional (UNINTER), Curitiba, Paraná, Brazil
| | - Ana Caroline Freitas Caetano de Sousa
- Departamento de Ciências Animais, Laboratório de Morfofisiologia Animal Aplicada (LABMORFA), Universidade Federal Rural do Semi-Árido (UFERSA), Mossoró, Rio Grande do Norte, Brazil
| | | | - Rysónely Maclay de Oliveira
- Programa de Pós-Graduação em Ciência Animal (PPGCA), Universidade Federal Rural do Semi-Árido (UFERSA), Mossoró, Rio Grande do Norte, Brazil.,Projeto Cetáceos da Costa Branca (PCCB), Universidade do Estado do Rio Grande do Norte (UERN), Mossoró, Rio Grande do Norte, Brazil
| | - Carlos Eduardo Bezerra de Moura
- Programa de Pós-Graduação em Ciência Animal (PPGCA), Universidade Federal Rural do Semi-Árido (UFERSA), Mossoró, Rio Grande do Norte, Brazil
| | - Alexandre Rodrigues Silva
- Programa de Pós-Graduação em Ciência Animal (PPGCA), Universidade Federal Rural do Semi-Árido (UFERSA), Mossoró, Rio Grande do Norte, Brazil
| | - Alexsandra Fernandes Pereira
- Programa de Pós-Graduação em Ciência Animal (PPGCA), Universidade Federal Rural do Semi-Árido (UFERSA), Mossoró, Rio Grande do Norte, Brazil
| | - Ana Bernadete Lima Fragoso
- Centro de Estudos e Monitoramento Ambiental (CEMAM), Areia Branca, Rio Grande do Norte, Brazil.,Projeto Cetáceos da Costa Branca (PCCB), Universidade do Estado do Rio Grande do Norte (UERN), Mossoró, Rio Grande do Norte, Brazil
| | - Flávio José de Lima Silva
- Centro de Estudos e Monitoramento Ambiental (CEMAM), Areia Branca, Rio Grande do Norte, Brazil.,Projeto Cetáceos da Costa Branca (PCCB), Universidade do Estado do Rio Grande do Norte (UERN), Mossoró, Rio Grande do Norte, Brazil.,Programa Regional de Pós-Graduação em Desenvolvimento e Meio Ambiente (PRODEMA), Universidade Federal do Rio Grande do Norte (UFRN), Natal, Rio Grande do Norte, Brazil
| | - Moacir Franco de Oliveira
- Programa de Pós-Graduação em Ciência Animal (PPGCA), Universidade Federal Rural do Semi-Árido (UFERSA), Mossoró, Rio Grande do Norte, Brazil
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Milsom WK, Kinkead R, Hedrick MS, Gilmour K, Perry S, Gargaglioni L, Wang T. Evolution of vertebrate respiratory central rhythm generators. Respir Physiol Neurobiol 2021; 295:103781. [PMID: 34481078 DOI: 10.1016/j.resp.2021.103781] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 07/03/2021] [Accepted: 08/29/2021] [Indexed: 12/01/2022]
Abstract
Tracing the evolution of the central rhythm generators associated with ventilation in vertebrates is hindered by a lack of information surrounding key transitions. To begin with, central rhythm generation has been studied in detail in only a few species from four vertebrate groups, lamprey, anuran amphibians, turtles, and mammals (primarily rodents). Secondly, there is a lack of information regarding the transition from water breathing fish to air breathing amniotes (reptiles, birds, and mammals). Specifically, the respiratory rhythm generators of fish appear to be single oscillators capable of generating both phases of the respiratory cycle (expansion and compression) and projecting to motoneurons in cranial nerves innervating bucco-pharyngeal muscles. In the amniotes we find oscillators capable of independently generating separate phases of the respiratory cycle (expiration and inspiration) and projecting to pre-motoneurons in the ventrolateral medulla that in turn project to spinal motoneurons innervating thoracic and abdominal muscles (reptiles, birds, and mammals). Studies of the one group of amphibians that lie at this transition (the anurans), raise intriguing possibilities but, for a variety of reasons that we explore, also raise unanswered questions. In this review we summarize what is known about the rhythm generating circuits associated with breathing that arise from the different rhombomeric segments in each of the different vertebrate classes. Assuming oscillating circuits form in every pair of rhombomeres in every vertebrate during development, we trace what appears to be the evolutionary fate of each and highlight the questions that remain to be answered to properly understand the evolutionary transitions in vertebrate central respiratory rhythm generation.
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Affiliation(s)
- W K Milsom
- Department of Zoology, University of British Columbia, Canada.
| | - R Kinkead
- Département de Pédiatrie, Université Laval, Canada
| | - M S Hedrick
- Department of Biological Sciences, California State University, Hayward, CA, USA
| | - K Gilmour
- Department of Biology, University of Ottawa, Canada
| | - S Perry
- Department of Biology, University of Ottawa, Canada
| | - L Gargaglioni
- Departamento de Morfologia e Fisiologia Animal, UNESP, Jaboticabal, Brazil
| | - T Wang
- Department of Zoophysiology, Aarhus University, Denmark
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Ventilation and gas exchange in two turtles: Podocnemis unifilis and Phrynops geoffroanus (Testudines: Pleurodira). Respir Physiol Neurobiol 2016; 224:125-31. [DOI: 10.1016/j.resp.2014.12.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2014] [Revised: 12/15/2014] [Accepted: 12/15/2014] [Indexed: 11/24/2022]
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5
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The metabolic cost of breathing in red-eared sliders: An attempt to resolve an old controversy. Respir Physiol Neurobiol 2016; 224:114-24. [DOI: 10.1016/j.resp.2015.10.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Revised: 10/14/2015] [Accepted: 10/20/2015] [Indexed: 11/18/2022]
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6
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Growth Rate and an Evaluation of Age Estimation for the Endangered Big-Headed Turtle ( Platysternon megacephalum) in China. J HERPETOL 2015. [DOI: 10.1670/12-166] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Lintner M, Weissenbacher A, Heiss E. The oropharyngeal morphology in the semiaquatic giant Asian pond turtle, Heosemys grandis, and its evolutionary implications. PLoS One 2012; 7:e46344. [PMID: 23029486 PMCID: PMC3460852 DOI: 10.1371/journal.pone.0046344] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Accepted: 08/31/2012] [Indexed: 11/22/2022] Open
Abstract
The oropharynx as a functional entity plays a fundamental role in feeding. Transitions from aquatic to terrestrial lifestyles in vertebrates demanded major changes of the oropharynx for the required adaptations to a different feeding environment. Extant turtles evolved terrestrial feeding modes in three families (testudinids, emydids, geoemydids)-independently from other amniotes-and are therefore important model organisms to reconstruct morpho-functional changes behind aquatic-terrestrial transitions. In this study we hypothesized that the oropharyngeal morphology in semiaquatic turtles of the geoemydid family shows parallels to testudinids, the only purely terrestrial extant lineage. We provide an in-depth description of the oropharynx in the semiaquatic geoemydid Heosemys grandis by using a combination of micro computed tomography (micro-CT) and subsequent digital in situ 3-D reconstruction, scanning electron microscopy (SEM), and histology. We show that H. grandis has a large tongue with rough papillose surface and well-developed lingual muscles. The attachment sites of the lingual muscles on the hyolingual skeleton and their courses within the tongue are nearly identical with testudinids. The hyolingual skeleton itself is mainly cartilaginous and shows distinct-but compared to testudinids rather small-anterior extensions of the hyoid body and hypoglossum. Oral glands are well developed in H. grandis but are smaller and simpler than in testudinids. Similarly, oropharyngeal keratinization was minimal and found only in the anterior palate, regions close to the beak, and tongue tip. We conclude that H. grandis shows distinct oropharyngeal morpho-functional adaptations for a terrestrial lifestyle but still retains characters typical for aquatic forms. This makes this species an important example showing the oropharyngeal adaptations behind aquatic-terrestrial transitions in turtles.
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Affiliation(s)
- Monika Lintner
- Department of Integrative Zoology, University of Vienna, Vienna, Austria
| | | | - Egon Heiss
- Department of Integrative Zoology, University of Vienna, Vienna, Austria
- Department of Biology, University of Antwerp, Antwerp, Belgium
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8
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Valente ALS, Martínez-Silvestre A, García-Guasch L, Riera-Tort A, Marco I, Lavin S, Cuenca R. Evaluation of pulmonary function in European land tortoises using whole-body plethysmography. Vet Rec 2012; 171:154, 1-5. [PMID: 22832080 DOI: 10.1136/vr.100799] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The aim of this study was to evaluate the use of whole-body plethysmography as a non-invasive method to determine the respiratory parameters and profiles in two tortoise species belonging to the genus Testudo. Pulmonary functions and volumetric parameters were determined in 10 adults of Testudo hermanni and in seven Testudo marginata animals, using whole-body plethysmography. A profile pattern was regularly observed: an inspiratory flow peak, an expiratory peak, an apnoea phase and a second expiratory peak, previous to the beginning of the next respiratory cycle. Positive and significant correlation was observed between the inspiratory time, weight and length of the tortoises. Larger tortoises showed a higher time of inhalation. The peak of inspiratory flow was correlated with the sex, being longer in the females. T. marginata had an inspiratory time longer than that of T. hermanii. In T. hermanii, differences related to the sex were observed in the tidal volume, peak inspiratory flow, peak expiratory flow, expiratory flow of 50 per cent and enhanced pause, which could be related to the smaller size of males. The results suggest that additional information on new technologies currently used in pet medicine or even in human medicine should be developed and adjusted as alternative ways to support the rehabilitation of turtles and tortoises.
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Affiliation(s)
- A L Schifino Valente
- Departmento de Morfologia, Universidade Federal de Pelotas, Instituto de Biologia, Campus Universitário s/n, Pelotas, Rio Grande do Sul, Caixa Postal 354, 96010-900, Brazil.
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Heiss E, Natchev N, Schwaha T, Salaberger D, Lemell P, Beisser C, Weisgram J. Oropharyngeal morphology in the basal tortoise Manouria emys emys with comments on form and function of the testudinid tongue. J Morphol 2011; 272:1217-29. [DOI: 10.1002/jmor.10978] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2010] [Revised: 03/17/2011] [Accepted: 03/21/2011] [Indexed: 11/06/2022]
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Shen JW, Pike DA, Du WG. Movements and Microhabitat Use of Translocated Big-Headed Turtles (Platysternon megacephalum) in Southern China. CHELONIAN CONSERVATION AND BIOLOGY 2010. [DOI: 10.2744/ccb-0833.1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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11
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Bauman JM, Chang YH. High-speed X-ray video demonstrates significant skin movement errors with standard optical kinematics during rat locomotion. J Neurosci Methods 2010; 186:18-24. [PMID: 19900476 PMCID: PMC2814909 DOI: 10.1016/j.jneumeth.2009.10.017] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2009] [Revised: 10/13/2009] [Accepted: 10/22/2009] [Indexed: 11/22/2022]
Abstract
The sophistication of current rodent injury and disease models outpaces that of the most commonly used behavioral assays. The first objective of this study was to measure rat locomotion using high-speed X-ray video to establish an accurate baseline for rat hindlimb kinematics. The second objective was to quantify the kinematics errors due to skin movement artefacts by simultaneously recording and comparing hindlimb kinematics derived from skin markers and from direct visualization of skeletal landmarks. Joint angle calculations from skin-derived kinematics yielded errors as high as 39 degrees in the knee and 31 degrees in the hip around paw contact with respect to the X-ray data. Triangulation of knee position from the ankle and hip skin markers provided closer, albeit still inaccurate, approximations of bone-derived, X-ray kinematics. We found that soft tissue movement errors are the result of multiple factors, the most impressive of which is overall limb posture. Treadmill speed had surprisingly little effect on kinematics errors. These findings illustrate the significance and context of skin movement error in rodent kinematics.
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Affiliation(s)
- Jay M Bauman
- School of Applied Physiology, Georgia Institute of Technology, Atlanta, GA 30332-0356, USA
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Landberg T, Mailhot JD, Brainerd EL. Lung ventilation during treadmill locomotion in a semi-aquatic turtle,Trachemys scripta. ACTA ACUST UNITED AC 2009; 311:551-62. [DOI: 10.1002/jez.478] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Vasilakos K, Wilson RJA, Kimura N, Remmers JE. Ancient gill and lung oscillators may generate the respiratory rhythm of frogs and rats. ACTA ACUST UNITED AC 2005; 62:369-85. [PMID: 15551345 DOI: 10.1002/neu.20102] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Though the mechanics of breathing differ fundamentally between amniotes and "lower" vertebrates, homologous rhythm generators may drive air breathing in all lunged vertebrates. In both frogs and rats, two coupled oscillators, one active during the inspiratory (I) phase and the other active during the preinspiratory (PreI) phase, have been hypothesized to generate the respiratory rhythm. We used opioids to uncouple these oscillators. In the intact rat, complete arrest of the external rhythm by opioid-induced suppression of the putative I oscillator, that is, pre-Bötzinger complex (PBC) oscillator, did not arrest the putative PreI oscillator. In the unanesthetized frog, the comparable PreI oscillator, that is, the putative buccal/gill oscillator, was refractory to opioids even though the comparable I oscillator, the putative lung oscillator, was arrested. Studies in en bloc brainstem preparations derived from both juvenile frogs and metamorphic tadpoles confirmed these results and suggested that opioids may play a role in the clustering of lung bursts into episodes. As the frog and rat respiratory circuitry produce functionally equivalent motor outputs during lung inflation, these data argue for a close homology between the frog and rat oscillators. We suggest that the respiratory rhythm of all lunged vertebrates is generated by paired coupled oscillators. These may have originated from the gill and lung oscillators of the earliest air breathers.
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Affiliation(s)
- Konstantinon Vasilakos
- Department of Medicine, University of Calgary, 3330 Hospital Drive, Calgary, Alberta, Canada T2N 4N1
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Balderas-Valdivia CJ, Ramírez-Bautista A. AVERSIVE BEHAVIOR OF BEADED LIZARD, HELODERMA HORRIDUM, TO SYMPATRIC AND ALLOPATRIC PREDATOR SNAKES. SOUTHWEST NAT 2005. [DOI: 10.1894/0038-4909(2005)050<0024:aboblh>2.0.co;2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Landberg T, Mailhot JD, Brainerd EL. Lung ventilation during treadmill locomotion in a terrestrial turtle, Terrapene carolina. J Exp Biol 2003; 206:3391-404. [PMID: 12939371 DOI: 10.1242/jeb.00553] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The limb girdles and lungs of turtles are both located within the bony shell, and therefore limb movements during locomotion could affect breathing performance. A mechanical conflict between locomotion and lung ventilation has been reported in adult green sea turtles, Chelonia mydas, in which breathing stops during terrestrial locomotion and resumes during pauses between bouts of locomotion. We measured lung ventilation during treadmill locomotion using pneumotach masks in three individual Terrapene carolina (mass 304-416 g) and found no consistent mechanical effects of locomotion on breathing performance. Relatively small tidal volumes (2.2+/-1.4 ml breath(-1); mean +/- S.D., N=3 individuals) coupled with high breath frequencies (36.6+/-26.4 breaths min(-1); mean +/- S.D., N=3 individuals) during locomotion yield mass-specific minute volumes that are higher than any previously reported for turtles (264+/-64 ml min kg(-1); mean +/- S.D., N=3 individuals). Minute volume was higher during locomotion than during recovery from exercise (P<0.01; paired t-test), and tidal volumes measured during locomotion were not significantly different from values measured during brief pauses between locomotor bouts or during recovery from exercise (P>0.05; two-way ANOVA). Since locomotion does not appear to conflict with breathing performance, the mechanism of lung ventilation must be either independent of, or coupled to, the stride cycle. The timing of peak airflow from breaths occurring during locomotion does not show any fixed phase relationship with the stride cycle. Additionally, the peak values of inhalatory and exhalatory airflow rates do not differ consistently with respect to the stride cycle. Together, these data indicate that T. carolina is not using respiratory-locomotor coupling and limb and girdle movements do not contribute to lung ventilation during locomotion. X-ray video recordings indicate that lung ventilation is achieved via bilateral activity of the transverse (exhalatory) and oblique (inhalatory) abdominal muscles. This specialized abdominal ventilation mechanism may have originally circumvented a mechanical conflict between breathing and locomotion in the ancestor of turtles and subsequently allowed the ribs to abandon their role in lung ventilation and to fuse to form the shell.
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Affiliation(s)
- Tobias Landberg
- Graduate Program in Organismic and Evolutionary Biology, University of Massachusetts-Amherst, 611 North Pleasant Street, Amherst, MA 01003, USA.
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