Neuroanatomy of the Cetacean Sensory Systems

De Vreese, Steffen; Orekhova, Ksenia; Morell, Maria; Gerussi, Tommaso; Graïc, Jean-Marie

doi:10.3390/ani14010066

Cited by 6 publications

(3 citation statements)

References 237 publications

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“…We identified ion channels associated with ear and otolith morphology anomalies, among other findings. Accompanying the specialized hearing capabilities in this mammalian group, neuroanatomical alterations affecting the inner ear and cranial nerves have been documented (De Vreese et al 2023).…”

Section: Resultsmentioning

confidence: 99%

“…3). This category encompasses all aspects of phenotypic changes within the nervous system attributed to the diverse sensory adaptations now thoroughly documented as originating from the transition to aquatic life (Ridgway 1988; Eldridge et al 2022; Racicot 2022; De Vreese et al 2023). These phenotypic changes include modifications in brain morphology, sensory processing, and motor control to support their aquatic lifestyle (Thewissen 2018).…”

Section: Resultsmentioning

confidence: 99%

“…The senses of cetaceans have radically changed in association with aquatic living (De Vreese et al 2023). The cetacean visual system has been modified to meet the challenges of the aquatic way of life, in which ion channels seem to be an important factor (Fig.…”

Section: Ion Channels With the Signature Of Positive Selection Are Re...mentioning

confidence: 99%

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Evolution of ion channels in cetaceans: A natural experiment in the Tree of life

Uribe

Nery

Zavala

et al. 2023

Preprint

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Cetaceans could be seen as a natural experiment within the tree of life in which a mammalian lineage changed from terrestrial to aquatic habitats. This shift involved extensive phenotypic modifications representing an opportunity to explore the genetic bases of phenotypic diversity. Furthermore, the availability of whole genome sequences in representative species of all main cetacean groups means that we are in a golden age for this type of study. Ion channels are a crucial component of the cellular machinery for the proper physiological functioning of all living species. This study aims to explore the evolution of ion channels during the evolutionary history of cetaceans. To do so, we created a bioinformatic pipeline to annotate the repertoire of ion channels in the genome of the species included in our sampling. Our main results show that cetaceans have fewer ion channels than non-cetacean mammals and that the signal of positive selection was found in ion channels related to heart, locomotion, and hearing phenotypes. Interestingly the NaV1.5 ion channel of most toothed whales (odontocetes) seems to be sensitive to TTX, similar to NaV1.7, given the presence of tyrosine, instead of cysteine, in a specific position of the ion channel. Finally, the gene turnover rate of the cetacean crown group is more than two times faster than non-cetacean mammals.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Evolution of ion channels in cetaceans: A natural experiment in the Tree of life

Uribe

Nery

Zavala

et al. 2023

Preprint

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Morphological characteristics of the unique periodontal structure in dolphins

Kodera,

Kajinishi,

Uekusa

et al. 2024

The Anatomical Record

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Although toothed whales have dentition peculiar to mammals, little attention has been paid to the periodontal tissues that support these characteristic teeth. In this study, we clarified the anatomical characteristics of the periodontal tissue in several species of Delphinidae through three‐dimensional observation using micro‐computed tomography, histological observations using decalcified sections, and immunohistochemical analysis. The results indicated that the teeth and the periodontal tissues of dolphins are morphologically unique among mammals. The alveolar bone was both crude and spongy. The lamina dura, a radiopaque line observed in the alveolar bone of common mammals, was thin in dolphins, and the teeth were attached to the trabeculae with the periodontal ligament (PDL). The alveolar sockets were massive for the size of the teeth. The PDL, a collagen fiber that fills the periodontal space, was well‐developed and peculiarly divided into two layers. The inner layer fibers radially spread out from the cementum, similar to the PDL in common mammals. However, the outer layer fibers penetrate the spongy bone in a complicated manner. The interstitial space between the inner and outer layers contained nerve fiber bundles that were thicker than those found in the PDL of other mammals. Sensory receptor‐like structures were observed at the terminal ends of the nerve fibers. These findings indicated that the dolphin PDL is more sensitive to dental stimuli than those of other mammals, suggesting that the dolphin dentition plays a functional role as a sensory receptor, similar to tactile hair.

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Synapsids and sensitivity: Broad survey of tetrapod trigeminal canal morphology supports an evolutionary trend of increasing facial tactile specialization in the mammal lineage

Miyamae,

Benoit,

Ruf

et al. 2024

The Anatomical Record

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The trigeminus nerve (cranial nerve V) is a large and significant conduit of sensory information from the face to the brain, with its three branches extending over the head to innervate a wide variety of integumentary sensory receptors, primarily tactile. The paths of the maxillary (V2) and mandibular (V3) divisions of the trigeminus frequently transit through dedicated canals within the bones of the upper and lower jaws, thus allowing this neuroanatomy to be captured in the fossil record and be available to interpretations of sensory ability in extinct taxa. Here, we use microCT and synchrotron scans from 38 extant and fossil species spanning a wide phylogenetic sample across tetrapods to investigate whether maxillary and mandibular canal morphology can be informative of sensory biology in the synapsid lineage. We found that in comparison to an amphibian and sauropsid outgroup, synapsids demonstrate a distinctive evolutionary pattern of change from canals that are highly ramified near the rostral tip of the jaws to canals with increasingly simplified morphology. This pattern is especially evident in the maxillary canal, which came to feature a shortened infraorbital canal terminating in a single large infraorbital foramen that serves as the outlet for branches of V2 that then enter the soft tissues of the face. A comparison with modern analogues supports the hypothesis that this morphological change correlates to an evolutionary history of synapsid‐specific innovations in facial touch. We interpret the highly ramified transitional form found in early nonmammalian synapsids as indicative of enhanced tactile sensitivity of the rostrum via direct or proximal contact, similar to tactile specialists such as probing shorebirds and alligators that possess similar proliferative ramifications of the maxillary and mandibular canals. The transition toward a simplified derived form that emerged among Mid‐Triassic prozostrodont cynodonts and is retained among modern mammals is a unique configuration correlated with an equally unique and novel tactile sensory apparatus: mobile mystacial whiskers. Our survey of maxillary and mandibular canals across a phylogenetic and ecological variety of tetrapods highlights the morphological diversity of these structures, but also the need to establish robust form‐function relationships for future interpretations of osteological correlates for sensory biology.

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Neuroanatomy of the Cetacean Sensory Systems

Cited by 6 publications

References 237 publications

Evolution of ion channels in cetaceans: A natural experiment in the Tree of life

Evolution of ion channels in cetaceans: A natural experiment in the Tree of life

Morphological characteristics of the unique periodontal structure in dolphins

Synapsids and sensitivity: Broad survey of tetrapod trigeminal canal morphology supports an evolutionary trend of increasing facial tactile specialization in the mammal lineage

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