Gheylen Daghfous | Université de Montréal (original) (raw)
Papers by Gheylen Daghfous
Text-fig. 4. Ancestral character value reconstruction for A) foot length, and B) the length of th... more Text-fig. 4. Ancestral character value reconstruction for A) foot length, and B) the length of the longest toe. Branch lengths are proportional to time and the reconstructed values (numbers next to arrows) are indicated at the base of the Anura and at the base of the Neobatrachia (vertical line). Red colors indicate high trait values and blue colors lower trait values.
Text-fig. 1. Ancestral character value reconstruction for A) the peak resultant force during jump... more Text-fig. 1. Ancestral character value reconstruction for A) the peak resultant force during jumping, and B) the peak jumping acceleration. Branch lengths are proportional to time and the reconstructed values (numbers next to arrows) are indicated at the base of the Anura and at the base of the Neobatrachia (vertical line). Red colors indicate high trait values and blue colors lower trait values.
Zoo Biology, 2022
In this paper, we cover 4 years of live fish transports that ranged from 14 to 200 h (8 days), an... more In this paper, we cover 4 years of live fish transports that ranged from 14 to 200 h (8 days), and bioloads from 3.8 to 76.9 kg/m3 . The key ingredients for success in all trips, where virtually no mortality occurred, was atributed to (1) pre-buffering the water with sodium bicarbonate and sodium carbonate at 50 g/m3 (each)-and/or ATM Alka-HaulTM at 25 g/m3 -and applying additional (partial or full) doses throughout each transport, whenever the tanks were accessible; (2) pre-quenching ammonia with ATM TriageTM at 32 g/m3 , and applying additional (partial or full) doses throughout each transport, whenever the tanks were accessible; (3) keeping the dissolved oxygen saturation rate above 100%, ideally above 150%; (4) Keeping temperature on the lower limit of each species' tolerance range; (5) Using foam fractionators to effectively eliminate organic matter from the water and (6) Using pure sine wave inverters, which allows for a steady supply of electrical current throughout the transport. The use of a 'preventive' versus 'corrective' pH buffering philosophy is also discussed.
The Journal of Experimental Biology, 2017
Olfactory sensory neurons innervate the olfactory bulb, where responses to different odorants gen... more Olfactory sensory neurons innervate the olfactory bulb, where responses to different odorants generate a chemotopic map of increased neural activity within different bulbar regions. In this study, insight into the basal pattern of neural organization of the vertebrate olfactory bulb was gained by investigating the lamprey. Retrograde labeling established that lateral and dorsal bulbar territories receive the axons of sensory neurons broadly distributed in the main olfactory epithelium and that the medial region receives sensory neuron input only from neurons projecting from the accessory olfactory organ. The response duration for local field potential recordings were similar in the lateral and dorsal regions, and both were longer than medial responses. All three regions responded to amino acid.odorants. The dorsal and medial regions, but not the lateral region, responded to steroids. These findings show evidence for olfactory streams in the sea lamprey olfactory bulb, the lateral re...
Journal of anatomy, Jan 28, 2017
Brain endocasts obtained from computed tomography (CT) are now widely used in the field of compar... more Brain endocasts obtained from computed tomography (CT) are now widely used in the field of comparative neuroanatomy. They provide an overview of the morphology of the brain and associated tissues located in the cranial cavity. Through anatomical comparisons between species, insights on the senses, the behavior, and the lifestyle can be gained. Although there are many studies dealing with mammal and bird endocasts, those performed on the brain endocasts of squamates are comparatively rare, thus limiting our understanding of their morphological variability and interpretations. Here, we provide the first comparative study of snake brain endocasts in order to bring new information about the morphology of these structures. Additionally, we test if the snake brain endocast encompasses a phylogenetic and/or an ecological signal. For this purpose, the digital endocasts of 45 snake specimens, including a wide diversity in terms of phylogeny and ecology, were digitized using CT, and compared ...
Frontiers in Neural Circuits, 2016
Sensorimotor transformation is one of the most fundamental and ubiquitous functions of the centra... more Sensorimotor transformation is one of the most fundamental and ubiquitous functions of the central nervous system (CNS). Although the general organization of the locomotor neural circuitry is relatively well understood, less is known about its activation by sensory inputs and its modulation. Utilizing the lamprey model, a detailed understanding of sensorimotor integration in vertebrates is emerging. In this article, we explore how the vertebrate CNS integrates sensory signals to generate motor behavior by examining the pathways and neural mechanisms involved in the transformation of cutaneous and olfactory inputs into motor output in the lamprey. We then review how 5-hydroxytryptamine (5-HT) acts on these systems by modulating both sensory inputs and motor output. A comprehensive review of this fundamental topic should provide a useful framework in the fields of motor control, sensorimotor integration and neuromodulation.
Les organes de Jacobson ou vomeronasaux sont des organes chimiosensoriels pairs situes dans la pa... more Les organes de Jacobson ou vomeronasaux sont des organes chimiosensoriels pairs situes dans la partie anterieure du toit buccal, a la base de la cavite nasale. La plupart des vertebres terrestres a l'exception des oiseaux, crocodiliens, mammifere marins et certains primates possedent un systeme vomeronasal fonctionnel. Ce systeme atteint son developpement le plus remarquable chez les squamates (lezards et serpents). Les connexions du systeme vomeronasal avec les cavites buccale et nasale sont tres variables au sein des tetrapodes. Ils peuvent etre en connexion avec la cavite buccale via le canal palatin (squamates) ou avec la cavite nasale via le canal nasal (monotremes et marsupiaux) ou encore avec la cavite buccale et la cavite nasale au moyen du canal naso-palatin (carnivores, rongeurs, insectivores, certains ongules et primates). Ces organes constituent le substrat anatomique de l'olfaction vomeronasale ou vomerolfaction, sens similaire a l'olfaction mais avec une se...
Journal of Great Lakes Research
Journal of Comparative Neurology
Solitary chemosensory cells (SCCs) and their innervating fibers are located in the respiratory sy... more Solitary chemosensory cells (SCCs) and their innervating fibers are located in the respiratory system of many vertebrates, including papillae on lamprey gill pores. In order to gain stronger insight for the role of these chemosensory cells, we examined immunocytochemical and innervation characteristics, as well as abundance at the different stages of the lamprey life cycle. The SCCs were distinguished from the surrounding epithelial cells by calretinin and phospholipase C140 immunoreactivity. Nerve fibers extended into the gill pore papillae, as far as the SCCs and serotonergic fibers extended from the underlying dermis into the papillar base. Gill pore papillae were absent and SCCs were sparse during the larval stage and in newly transformed lamprey. Few SCCs were located on small nub‐like papillae during the parasitic juvenile stage, but SCCs were abundant on prominent papillae in migrating and in spawning adults. These findings show similarities between the SCCs in lampreys and other vertebrates and suggest that gill SCC function may be important during the feeding juvenile and the adult stages of the lamprey life cycle.
Journal of Comparative Neurology
Molecules present in an animal's environment can indicate the presence of predators, food, or... more Molecules present in an animal's environment can indicate the presence of predators, food, or sexual partners and consequently, induce migratory, reproductive, foraging, or escape behaviors. Three sensory systems, the olfactory, gustatory, and solitary chemosensory cell (SCC) systems detect chemical stimuli in vertebrates. While a great deal of research has focused on the olfactory and gustatory system over the years, it is only recently that significant attention has been devoted to the SCC system. The SCCs are microvillous cells that were first discovered on the skin of fish, and later in amphibians, reptiles, and mammals. Lampreys also possess SCCs that are particularly numerous on cutaneous papillae. However, little is known regarding their precise distribution, innervation, and function. Here, we show that sea lampreys (Petromyzon marinus L.) have cutaneous papillae located around the oral disk, nostril, gill pores, and on the dorsal fins and that SCCs are particularly numerous on these papillae. Tract‐tracing experiments demonstrated that the oral and nasal papillae are innervated by the trigeminal nerve, the gill pore papillae are innervated by branchial nerves, and the dorsal fin papillae are innervated by spinal nerves. We also characterized the response profile of gill pore papillae to some chemicals and showed that trout‐derived chemicals, amino acids, and a bile acid produced potent responses. Together with a companion study (Suntres et al., Journal of Comparative Neurology, this issue), our results provide new insights on the function and evolution of the SCC system in vertebrates.
Journal of Comparative Neurology
Detection of chemical cues is important to guide locomotion in association with feeding and sexua... more Detection of chemical cues is important to guide locomotion in association with feeding and sexual behavior. Two neural pathways responsible for odor‐evoked locomotion have been characterized in the sea lamprey (Petromyzon marinus L.), a basal vertebrate. There is a medial pathway originating in the medial olfactory bulb (OB) and a lateral pathway originating from the rest of the OB. These olfactomotor pathways are present throughout the life cycle of lampreys, but olfactory‐driven behaviors differ according to the developmental stage. Among possible mechanisms, dopaminergic (DA) modulation in the OB might explain the behavioral changes. Here, we examined DA modulation of olfactory transmission in lampreys. Immunofluorescence against DA revealed immunoreactivity in the OB that was denser in the medial part (medOB), where processes were observed close to primary olfactory afferents and projection neurons. Dopaminergic neurons labeled by tracer injections in the medOB were located in the OB, the posterior tuberculum, and the dorsal hypothalamic nucleus, suggesting the presence of both intrinsic and extrinsic DA innervation. Electrical stimulation of the olfactory nerve in an in vitro whole‐brain preparation elicited synaptic responses in reticulospinal cells that were modulated by DA. Local injection of DA agonists in the medOB decreased the reticulospinal cell responses whereas the D2 receptor antagonist raclopride increased the response amplitude. These observations suggest that DA in the medOB could modulate odor‐evoked locomotion. Altogether, these results show the presence of a DA innervation within the medOB that may play a role in modulating olfactory inputs to the motor command system of lampreys.
Detecting and locating prey are key to predatory success within trophic chains. Predators use var... more Detecting and locating prey are key to predatory success within trophic chains. Predators use various signals through specialized visual, olfactory, auditory or tactile sensory systems to pinpoint their prey. Snakes chemically sense their prey through a highly developed auxiliary olfactory sense organ, the vomeronasal organ (VNO). In natricine snakes that are able to feed on land and water, the VNO plays a critical role in predatory behavior by detecting cues, known as vomodors, which are produced by their potential prey. However, the chemical nature of these cues remains unclear. Recently, we demonstrated that specific proteins–parvalbumins–present in the cutaneous mucus of the common frog (Rana temporaria) may be natural chemoattractive proteins for these snakes. Here, we show that parvalbumins and parvalbumin-like proteins, which are mainly intracellular, are physiologically present in the epidermal mucous cells and mucus of several frog and fish genera from both fresh and salt w...
Biology Letters, 2010
Chamaeleons are well known for their unique suite of morphological adaptations. Whereas most cham... more Chamaeleons are well known for their unique suite of morphological adaptations. Whereas most chamaeleons are arboreal and have long tails, which are used during arboreal acrobatic manoeuvres, Malagasy dwarf chamaeleons (Brookesia) are small terrestrial lizards with relatively short tails. Like other chamaeleons, Brookesia have grasping feet and use these to hold on to narrow substrates. However, in contrast to other chamaeleons, Brookesia place the tail on the substrate when walking on broad substrates, thus improving stability. Using threedimensional synchrotron X-ray phase-contrast imaging, we demonstrate a set of unique specializations in the tail associated with the use of the tail during locomotion. Additionally, our imaging demonstrates specializations of the inner ear that may allow these animals to detect small accelerations typical of their slow, terrestrial mode of locomotion. These data suggest that the evolution of a terrestrial lifestyle in Brookesia has gone hand-in-hand with the evolution of a unique mode of locomotion and a suite of morphological adaptations allowing for stable locomotion on a wide array of substrates.
Text-fig. 4. Ancestral character value reconstruction for A) foot length, and B) the length of th... more Text-fig. 4. Ancestral character value reconstruction for A) foot length, and B) the length of the longest toe. Branch lengths are proportional to time and the reconstructed values (numbers next to arrows) are indicated at the base of the Anura and at the base of the Neobatrachia (vertical line). Red colors indicate high trait values and blue colors lower trait values.
Text-fig. 1. Ancestral character value reconstruction for A) the peak resultant force during jump... more Text-fig. 1. Ancestral character value reconstruction for A) the peak resultant force during jumping, and B) the peak jumping acceleration. Branch lengths are proportional to time and the reconstructed values (numbers next to arrows) are indicated at the base of the Anura and at the base of the Neobatrachia (vertical line). Red colors indicate high trait values and blue colors lower trait values.
Zoo Biology, 2022
In this paper, we cover 4 years of live fish transports that ranged from 14 to 200 h (8 days), an... more In this paper, we cover 4 years of live fish transports that ranged from 14 to 200 h (8 days), and bioloads from 3.8 to 76.9 kg/m3 . The key ingredients for success in all trips, where virtually no mortality occurred, was atributed to (1) pre-buffering the water with sodium bicarbonate and sodium carbonate at 50 g/m3 (each)-and/or ATM Alka-HaulTM at 25 g/m3 -and applying additional (partial or full) doses throughout each transport, whenever the tanks were accessible; (2) pre-quenching ammonia with ATM TriageTM at 32 g/m3 , and applying additional (partial or full) doses throughout each transport, whenever the tanks were accessible; (3) keeping the dissolved oxygen saturation rate above 100%, ideally above 150%; (4) Keeping temperature on the lower limit of each species' tolerance range; (5) Using foam fractionators to effectively eliminate organic matter from the water and (6) Using pure sine wave inverters, which allows for a steady supply of electrical current throughout the transport. The use of a 'preventive' versus 'corrective' pH buffering philosophy is also discussed.
The Journal of Experimental Biology, 2017
Olfactory sensory neurons innervate the olfactory bulb, where responses to different odorants gen... more Olfactory sensory neurons innervate the olfactory bulb, where responses to different odorants generate a chemotopic map of increased neural activity within different bulbar regions. In this study, insight into the basal pattern of neural organization of the vertebrate olfactory bulb was gained by investigating the lamprey. Retrograde labeling established that lateral and dorsal bulbar territories receive the axons of sensory neurons broadly distributed in the main olfactory epithelium and that the medial region receives sensory neuron input only from neurons projecting from the accessory olfactory organ. The response duration for local field potential recordings were similar in the lateral and dorsal regions, and both were longer than medial responses. All three regions responded to amino acid.odorants. The dorsal and medial regions, but not the lateral region, responded to steroids. These findings show evidence for olfactory streams in the sea lamprey olfactory bulb, the lateral re...
Journal of anatomy, Jan 28, 2017
Brain endocasts obtained from computed tomography (CT) are now widely used in the field of compar... more Brain endocasts obtained from computed tomography (CT) are now widely used in the field of comparative neuroanatomy. They provide an overview of the morphology of the brain and associated tissues located in the cranial cavity. Through anatomical comparisons between species, insights on the senses, the behavior, and the lifestyle can be gained. Although there are many studies dealing with mammal and bird endocasts, those performed on the brain endocasts of squamates are comparatively rare, thus limiting our understanding of their morphological variability and interpretations. Here, we provide the first comparative study of snake brain endocasts in order to bring new information about the morphology of these structures. Additionally, we test if the snake brain endocast encompasses a phylogenetic and/or an ecological signal. For this purpose, the digital endocasts of 45 snake specimens, including a wide diversity in terms of phylogeny and ecology, were digitized using CT, and compared ...
Frontiers in Neural Circuits, 2016
Sensorimotor transformation is one of the most fundamental and ubiquitous functions of the centra... more Sensorimotor transformation is one of the most fundamental and ubiquitous functions of the central nervous system (CNS). Although the general organization of the locomotor neural circuitry is relatively well understood, less is known about its activation by sensory inputs and its modulation. Utilizing the lamprey model, a detailed understanding of sensorimotor integration in vertebrates is emerging. In this article, we explore how the vertebrate CNS integrates sensory signals to generate motor behavior by examining the pathways and neural mechanisms involved in the transformation of cutaneous and olfactory inputs into motor output in the lamprey. We then review how 5-hydroxytryptamine (5-HT) acts on these systems by modulating both sensory inputs and motor output. A comprehensive review of this fundamental topic should provide a useful framework in the fields of motor control, sensorimotor integration and neuromodulation.
Les organes de Jacobson ou vomeronasaux sont des organes chimiosensoriels pairs situes dans la pa... more Les organes de Jacobson ou vomeronasaux sont des organes chimiosensoriels pairs situes dans la partie anterieure du toit buccal, a la base de la cavite nasale. La plupart des vertebres terrestres a l'exception des oiseaux, crocodiliens, mammifere marins et certains primates possedent un systeme vomeronasal fonctionnel. Ce systeme atteint son developpement le plus remarquable chez les squamates (lezards et serpents). Les connexions du systeme vomeronasal avec les cavites buccale et nasale sont tres variables au sein des tetrapodes. Ils peuvent etre en connexion avec la cavite buccale via le canal palatin (squamates) ou avec la cavite nasale via le canal nasal (monotremes et marsupiaux) ou encore avec la cavite buccale et la cavite nasale au moyen du canal naso-palatin (carnivores, rongeurs, insectivores, certains ongules et primates). Ces organes constituent le substrat anatomique de l'olfaction vomeronasale ou vomerolfaction, sens similaire a l'olfaction mais avec une se...
Journal of Great Lakes Research
Journal of Comparative Neurology
Solitary chemosensory cells (SCCs) and their innervating fibers are located in the respiratory sy... more Solitary chemosensory cells (SCCs) and their innervating fibers are located in the respiratory system of many vertebrates, including papillae on lamprey gill pores. In order to gain stronger insight for the role of these chemosensory cells, we examined immunocytochemical and innervation characteristics, as well as abundance at the different stages of the lamprey life cycle. The SCCs were distinguished from the surrounding epithelial cells by calretinin and phospholipase C140 immunoreactivity. Nerve fibers extended into the gill pore papillae, as far as the SCCs and serotonergic fibers extended from the underlying dermis into the papillar base. Gill pore papillae were absent and SCCs were sparse during the larval stage and in newly transformed lamprey. Few SCCs were located on small nub‐like papillae during the parasitic juvenile stage, but SCCs were abundant on prominent papillae in migrating and in spawning adults. These findings show similarities between the SCCs in lampreys and other vertebrates and suggest that gill SCC function may be important during the feeding juvenile and the adult stages of the lamprey life cycle.
Journal of Comparative Neurology
Molecules present in an animal's environment can indicate the presence of predators, food, or... more Molecules present in an animal's environment can indicate the presence of predators, food, or sexual partners and consequently, induce migratory, reproductive, foraging, or escape behaviors. Three sensory systems, the olfactory, gustatory, and solitary chemosensory cell (SCC) systems detect chemical stimuli in vertebrates. While a great deal of research has focused on the olfactory and gustatory system over the years, it is only recently that significant attention has been devoted to the SCC system. The SCCs are microvillous cells that were first discovered on the skin of fish, and later in amphibians, reptiles, and mammals. Lampreys also possess SCCs that are particularly numerous on cutaneous papillae. However, little is known regarding their precise distribution, innervation, and function. Here, we show that sea lampreys (Petromyzon marinus L.) have cutaneous papillae located around the oral disk, nostril, gill pores, and on the dorsal fins and that SCCs are particularly numerous on these papillae. Tract‐tracing experiments demonstrated that the oral and nasal papillae are innervated by the trigeminal nerve, the gill pore papillae are innervated by branchial nerves, and the dorsal fin papillae are innervated by spinal nerves. We also characterized the response profile of gill pore papillae to some chemicals and showed that trout‐derived chemicals, amino acids, and a bile acid produced potent responses. Together with a companion study (Suntres et al., Journal of Comparative Neurology, this issue), our results provide new insights on the function and evolution of the SCC system in vertebrates.
Journal of Comparative Neurology
Detection of chemical cues is important to guide locomotion in association with feeding and sexua... more Detection of chemical cues is important to guide locomotion in association with feeding and sexual behavior. Two neural pathways responsible for odor‐evoked locomotion have been characterized in the sea lamprey (Petromyzon marinus L.), a basal vertebrate. There is a medial pathway originating in the medial olfactory bulb (OB) and a lateral pathway originating from the rest of the OB. These olfactomotor pathways are present throughout the life cycle of lampreys, but olfactory‐driven behaviors differ according to the developmental stage. Among possible mechanisms, dopaminergic (DA) modulation in the OB might explain the behavioral changes. Here, we examined DA modulation of olfactory transmission in lampreys. Immunofluorescence against DA revealed immunoreactivity in the OB that was denser in the medial part (medOB), where processes were observed close to primary olfactory afferents and projection neurons. Dopaminergic neurons labeled by tracer injections in the medOB were located in the OB, the posterior tuberculum, and the dorsal hypothalamic nucleus, suggesting the presence of both intrinsic and extrinsic DA innervation. Electrical stimulation of the olfactory nerve in an in vitro whole‐brain preparation elicited synaptic responses in reticulospinal cells that were modulated by DA. Local injection of DA agonists in the medOB decreased the reticulospinal cell responses whereas the D2 receptor antagonist raclopride increased the response amplitude. These observations suggest that DA in the medOB could modulate odor‐evoked locomotion. Altogether, these results show the presence of a DA innervation within the medOB that may play a role in modulating olfactory inputs to the motor command system of lampreys.
Detecting and locating prey are key to predatory success within trophic chains. Predators use var... more Detecting and locating prey are key to predatory success within trophic chains. Predators use various signals through specialized visual, olfactory, auditory or tactile sensory systems to pinpoint their prey. Snakes chemically sense their prey through a highly developed auxiliary olfactory sense organ, the vomeronasal organ (VNO). In natricine snakes that are able to feed on land and water, the VNO plays a critical role in predatory behavior by detecting cues, known as vomodors, which are produced by their potential prey. However, the chemical nature of these cues remains unclear. Recently, we demonstrated that specific proteins–parvalbumins–present in the cutaneous mucus of the common frog (Rana temporaria) may be natural chemoattractive proteins for these snakes. Here, we show that parvalbumins and parvalbumin-like proteins, which are mainly intracellular, are physiologically present in the epidermal mucous cells and mucus of several frog and fish genera from both fresh and salt w...
Biology Letters, 2010
Chamaeleons are well known for their unique suite of morphological adaptations. Whereas most cham... more Chamaeleons are well known for their unique suite of morphological adaptations. Whereas most chamaeleons are arboreal and have long tails, which are used during arboreal acrobatic manoeuvres, Malagasy dwarf chamaeleons (Brookesia) are small terrestrial lizards with relatively short tails. Like other chamaeleons, Brookesia have grasping feet and use these to hold on to narrow substrates. However, in contrast to other chamaeleons, Brookesia place the tail on the substrate when walking on broad substrates, thus improving stability. Using threedimensional synchrotron X-ray phase-contrast imaging, we demonstrate a set of unique specializations in the tail associated with the use of the tail during locomotion. Additionally, our imaging demonstrates specializations of the inner ear that may allow these animals to detect small accelerations typical of their slow, terrestrial mode of locomotion. These data suggest that the evolution of a terrestrial lifestyle in Brookesia has gone hand-in-hand with the evolution of a unique mode of locomotion and a suite of morphological adaptations allowing for stable locomotion on a wide array of substrates.