scholarly journals Comparative anatomy of the middle ear in some lizard species with comments on the evolutionary changes within Squamata

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11722
Author(s):  
Paola María Sánchez-Martínez ◽  
Juan D. Daza ◽  
Julio Mario Hoyos
Keyword(s):  
Middle Ear ◽  
Comparative Anatomy ◽  
General Structure ◽  
Main Function ◽  
Ancestral State ◽  
Sound Waves ◽  
Ancestral Reconstruction ◽  
Lizard Species ◽  
Evolutionary Changes ◽  
Axis Length

The skeleton of the middle ear of lizards is composed of three anatomical elements: columella, extracolumella, and tympanic membrane, with some exceptions that show modifications of this anatomy. The main function of the middle ear is transforming sound waves into vibrations and transmitting these to the inner ear. Most middle ear studies mainly focus on its functional aspects, while few describe the anatomy in detail. In lizards, the morphology of the columella is highly conservative, while the extracolumella shows variation in its presence/absence, size, and the number of processes present on the structure. In this work, we used diaphanized and double-stained specimens of 38 species of lizards belonging to 24 genera to study the middle ear’s morphology in a comparative framework. Results presented here indicate more variation in the morphology of the extracolumella than previously known. This variation in the extracolumella is found mainly in the pars superior and anterior processes, while the pars inferior and the posterior process are more constant in morphology. We also provide new information about the shape of gekkotan extracolumella, including traits that are diagnostic for the iguanid and gekkonid middle ear types. The data collected in this study were combined with information from published descriptive works. The new data included here refers to the length of the columella relative to the extracolumella central axis length, the general structure of the extracolumella, and the presence of the internal process. These characters were included in ancestral reconstruction analysis using Bayesian and parsimony approaches. The results indicate high levels of homoplasy in the variation of the columella-extracolumella ratio, providing a better understanding of the ratio variation among lizards. Additionally, the presence of four processes in the extracolumella is the ancestral state for Gekkota, Pleurodonta, and Xantusiidae, and the absence of the internal processes is the ancestral state for Gekkota, Gymnophthalmidae, and Scincidae; despite the fact that these groups convergently develop these character states, they could be used in combination with other characters to diagnose these clades. The posterior extension in the pars superior and an anterior process with some small and sharp projections is also a diagnostic trait for Gekkota. A more accurate description of each process of the extracolumella and its variation needs to be evaluated in a comprehensive analysis, including a greater number of species. Although the number of taxa sampled in this study is small considering the vast diversity of lizards, the results provide an overall idea of the amount of variation of the middle ear while helping to infer the evolutionary history of the lizard middle ear.

scholarly journals Flowering plant embryos: How did we end up here?

2021 ◽  
Author(s):  
Stefan A. Rensing ◽  
Dolf Weijers
Keyword(s):  
Current Knowledge ◽  
General Structure ◽  
Three Dimensional ◽  
Flowering Plants ◽  
Flowering Plant ◽  
Adult Plant ◽  
Ancestral State ◽  
Evolutionary Trajectory ◽  
Current State ◽  
Plant Embryo

AbstractThe seeds of flowering plants are sexually produced propagules that ensure dispersal and resilience of the next generation. Seeds harbor embryos, three dimensional structures that are often miniatures of the adult plant in terms of general structure and primordial organs. In addition, embryos contain the meristems that give rise to post-embryonically generated structures. However common, flowering plant embryos are an evolutionary derived state. Flowering plants are part of a much larger group of embryo-bearing plants, aptly termed Embryophyta. A key question is what evolutionary trajectory led to the emergence of flowering plant embryos. In this opinion, we deconstruct the flowering plant embryo and describe the current state of knowledge of embryos in other plant lineages. While we are far yet from understanding the ancestral state of plant embryogenesis, we argue what current knowledge may suggest and how the knowledge gaps may be closed.

scholarly journals The comparative anatomy of the pig middle ear cavity: a model for middle ear inflammation in the human?

1998 ◽  
Vol 192 (3) ◽  
pp. 359-368 ◽  
Author(s):  
J. P. PRACY ◽  
A. WHITE ◽  
Y. MUSTAFA ◽  
D. SMITH ◽  
M. E. PERRY
Keyword(s):  
Middle Ear ◽  
Comparative Anatomy

scholarly journals Ancestral reconstruction reveals mechanisms of ERK regulatory evolution

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Dajun Sang ◽  
Sudarshan Pinglay ◽  
Rafal P Wiewiora ◽  
Myvizhi E Selvan ◽  
Hua Jane Lou ◽  
...  
Keyword(s):  
Amino Acid ◽  
Protein Kinases ◽  
Human Cells ◽  
Ancestral State ◽  
Ancestral Reconstruction ◽  
Regulatory Evolution ◽  
Evolutionary Mechanisms ◽  
Kinase Specificity ◽  
Shed Light

Protein kinases are crucial to coordinate cellular decisions and therefore their activities are strictly regulated. Previously we used ancestral reconstruction to determine how CMGC group kinase specificity evolved (Howard et al., 2014). In the present study, we reconstructed ancestral kinases to study the evolution of regulation, from the inferred ancestor of CDKs and MAPKs, to modern ERKs. Kinases switched from high to low autophosphorylation activity at the transition to the inferred ancestor of ERKs 1 and 2. Two synergistic amino acid changes were sufficient to induce this change: shortening of the β3-αC loop and mutation of the gatekeeper residue. Restoring these two mutations to their inferred ancestral state led to a loss of dependence of modern ERKs 1 and 2 on the upstream activating kinase MEK in human cells. Our results shed light on the evolutionary mechanisms that led to the tight regulation of a kinase that is central in development and disease.

scholarly journals Gene therapy as a possible option to treat hereditary hearing loss

2020 ◽  
Vol 32 (2) ◽  
pp. 149-159
Author(s):  
Michael Morgan ◽  
Juliane W. Schott ◽  
Axel Rossi ◽  
Christian Landgraf ◽  
Athanasia Warnecke ◽  
...  
Keyword(s):  
Gene Therapy ◽  
Hearing Loss ◽  
Middle Ear ◽  
Hearing Aids ◽  
Spiral Ganglion ◽  
Primary Auditory Cortex ◽  
Auditory Pathway ◽  
Therapeutic Strategies ◽  
Sound Waves ◽  
Ganglion Neurons

Abstract The process of hearing involves a series of events. The energy of sound is captured by the outer ear and further transferred through the external auditory canal to the middle ear. In the middle ear, sound waves are converted into movements of the tympanic membrane and the ossicles, thereby amplifying the pressure so that it is sufficient to cause movement of the cochlear fluid. The traveling wave within the cochlea leads to depolarization of the inner ear hair cells that, in turn, release the neurotransmitter glutamate. Thereby, the spiral ganglion neurons are activated to transfer the signals via the auditory pathway to the primary auditory cortex. This complex combination of mechanosensory and physiological mechanisms involves many distinct types of cells, the function of which are impacted by numerous proteins, including those involved in ion channel activity, signal transduction and transcription. In the last 30 years, pathogenic variants in over 150 genes were found to be linked to hearing loss. Hearing loss affects over 460 million people world-wide, and current treatment approaches, such as hearing aids and cochlear implants, serve to improve hearing capacity but do not address the underlying genetic cause of hearing loss. Therefore, therapeutic strategies designed to correct the genetic defects causative for hearing loss offer the possibility to treat these patients. In this review, we will discuss genetic causes of hearing loss, novel gene therapeutic strategies to correct hearing loss due to gene defects and some of the preclinical studies in hearing loss animal models as well as the clinical translation of gene therapy approaches to treat hearing loss patients.

Comparative Anatomy of Eustachian Tube and Middle Ear Cavity in Animal Models for Otitis Media

1982 ◽  
Vol 91 (1) ◽  
pp. 82-89 ◽  
Author(s):  
Hal J. Daniel ◽  
Jack E. Brinn ◽  
Robert S. Fulghum ◽  
Kathryn A. Barrett
Keyword(s):  
Animal Models ◽  
Otitis Media ◽  
Eustachian Tube ◽  
Middle Ear ◽  
Animal Species ◽  
Comparative Anatomy ◽  
Goblet Cells ◽  
Naturally Occurring ◽  
High Incidence ◽  
Seromucous Glands

The comparative anatomy of the normal eustachian tube (ET) and normal middle ear cavity of three animal species (rat, gerbil, and chinchilla) is described relating to the usefulness of these animals as models for otitis media (OM). Routine histological and anatomical techniques and procedures were used. The gerbil and chinchilla, although of different sizes, are quite similar, having hypertrophied middle ear bullae, nearly vertical ET, and similar histology including seromucous glands draining directly into the ET. In contrast, the rat has a small bulla, a nearly horizontal ET, and a large concentration of goblet cells but few mucous glands in the ET. It appears that the chinchilla and the gerbil may serve as alternative models for OM research. Chinchillas and gerbils are relatively free of naturally occurring OM, while the rat has a high incidence of naturally occurring OM.

Shrapnell’s membrane in a mammal exposed to extreme pressure variations: morphological and radiological observations in the hooded seal

2003 ◽  
Vol 117 (10) ◽  
pp. 756-762
Author(s):  
Lars-Eric Stenfors ◽  
Helga-Marie Bye ◽  
Tapani Tikkakoski
Keyword(s):  
Middle Ear ◽  
Lateral Wall ◽  
Main Function ◽  
Extreme Pressure ◽  
Thin Sections ◽  
Hooded Seal ◽  
Pressure Equalization ◽  
Pars Tensa ◽  
Ear Ossicles ◽  
Temporal Bones

The function of Shrapnell’s membrane (pars flaccida; PF) in middle-ear mechanics is still an enigma, though numerous proposals have been put forward, e.g. protection of pars tensa, equalizing of middle-ear pressure, sound transmission, and the site of origin of otitis media. In this study the PF was studied in a mammal (the hooded seal) which exposes itself to extreme pressure differences (from 1 to 100 atmospheres) when diving.Formaldehyde-fixed temporal bones obtained from newborn, one-year-old, and adult seals (three of each) were cleansed and decalcified in 10 per cent EDTA. The lateral wall of the middle-ear cavity, including the whole tympanic membrane with its bony surroundings, was then excised and photodocumented. Thin sections were cut parallel with, and perpendicular to, the handle of the malleus, stained with haematoxylin-eosin, toluidine blue or Giemsa stain and examined under a light microscope. One seal head was subjected to high resolution computerized tomography (HRCT) before sectioning. The PF was observed to be a narrow fissure measuring a maximum of 0.8 mm between processus brevis of the malleus and the notch of Rivinus in pars squamosa (pars tensa diameter 10–12 mm). It seems unlikely that the PF of the hooded seal participates in pressure equalization in the middle ear. The main function of the lateral wall of the attic, including the minimal PF, appears to be to protect the middle-ear ossicles and allow movement of the malleus.

scholarly journals Territorial Displays of the Ctenophorus decresii Complex: A Story of Local Adaptations

2021 ◽  
Vol 9 ◽  
Author(s):  
Jose A. Ramos ◽  
Richard A. Peters
Keyword(s):  
Motor Pattern ◽  
Habitat Characteristics ◽  
Model Systems ◽  
Ancestral State ◽  
Lizard Species ◽  
Motor Patterns ◽  
Local Adaptations ◽  
Behavioral Traits ◽  
Signal Contrast ◽  
Motion Speed

Closely related species make for interesting model systems to study the evolution of signaling behavior because they share evolutionary history but have also diverged to the point of reproductive isolation. This means that while they may have some behavioral traits in common, courtesy of a common ancestor, they are also likely to show local adaptations. The Ctenophorus decresii complex is such a system, and comprises six closely related agamid lizard species from Australia: C. decresii, C. fionni, C. mirrityana, C. modestus, C. tjanjalka, and C. vadnappa. In this study, we analyze the motion displays of five members of the C. decresii complex in the context of their respective habitats by comparing signal structure, habitat characteristics and signal contrast between all species. Motor pattern use and the temporal sequence of motor patterns did not differ greatly, but the motion speed distributions generated during the displays were different for all species. There was also variation in the extent to which signals contrasted with plant motion, with C. vadnappa performing better than the other species at all habitats. Overall, this study provides evidence that members of the C. decresii complex exhibit local adaptations in signaling behavior to their respective habitat, but they also maintain some morphological and behavioral traits in common, which is likely a consequence from the ancestral state.

scholarly journals FISIKA MEDIK PROSES PENDENGARAN

2012 ◽  
Vol 36 (2) ◽  
pp. 155
Author(s):  
Lili Irawati
Keyword(s):  
Resonance Frequency ◽  
Middle Ear ◽  
Sound Wave ◽  
Hair Cells ◽  
Sense Organ ◽  
Electrical Signal ◽  
Oval Window ◽  
Main Function ◽  
External Ear ◽  
Nerve Signal

AbstrakSuara yang didengar telinga manusia mengalami perubahan dari sinyal akustik yang bersifat mekanik menjadi sinyal listrik yang diteruskan saraf pendengaran ke otak. Proses mendengar tentunya tidak lepas dari organ pendengaran manusia yakni telinga.Telinga terdiri atas tiga bagian dasar, yaitu telinga bagian luar, telinga bagian tengah dan telinga bagian dalam. Setiap bagian telinga bekerja dengan tugas khusus untuk mendeteksi dan menginterpretasikan bunyi.Telinga bagian luar fungsi utamanya adalah mengumpulkan dan menghubungkan suara menuju meatus akustikus eksterna. Telinga bagian tengah terdiri dari 3 buah tulang (ossicle) yang akan mengamplifikasikan tekanan 20 kali dari gelombang suara untuk menghasilkan getaran cairan pada koklea. Pada telinga bagian dalam terdapat koklea, membran basilaris membentuk dasar duktus koklear. Membran basilaris ini sangat penting karena di dalamnya terdapat organ korti yang merupakan organ perasa pendengaran. Organ corti, yang terletak di atas membran basilaris di seluruh panjangnya, mengandung sel rambut yang merupakan reseptor suara. Sel rambut menghasilkan sinyal saraf jika rambut permukaannya mengalami perubahan bentuk secara mekanik akibat gerakan cairan di telinga dalam. Resonansi frekuensi tinggi dari membran basilaris terjadi dekat basis, tempat gelombang suara memasuki koklea melalui jendela oval dan resonansi frekuensi rendah terjadi dekat apeks. Sel rambut dalam yang mengubah gaya mekanik suara (getaran cairan koklea) menjadi impuls listrik pendengaran (potensial aksi yang menyampaikan pesan pendengaran ke korteks serebri).Kata kunci: Proses pendengaranAbstractSound heard by human ears undergo change from mechanical accustic signal to electrical signal continued by hearing nerves to brain. Of course the hearing process do not get out from human hearing organs in this case is ear.Ear comprise the three principle portions, external ear, middle ear, and internal ear. Each portion work with special task to detect and interpret the sound.The main function of the external ear is collecting and connecting sound toward the meatus acusticus externa. Middle ear consist three bones (ossicle) that will amplify pressure of 20 times than sound wave to yield fluid vibrationin the cochlear. In internal ear there are cochlear, basillary membrane establish cochlear duct base. The basillary membrane is most important because in it internal portion there are corti organs which is hearing sense organ. The corti organ, located on basillary membrane in entire its length, contain hair cells which is the soundTINJAUAN PUSTAKA156receptors. The hair cells yield nerve signal if surface hair undergo mechanically transformation result from fluid movement in internal ear. The high resonance frequency from basillary membrane take place near the base, sound wave site enter cochlear via oval window and low resonance frequency take place near the apex. The inner hair cells change mechanical sound style (the cochlear fluid vibration) become electrical impulse of hearing (potential act delivering hearing messenger to cerebral cortex).Key word : hearing process

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