Eublepharis Macularius Research Articles

Effects of regional hypoxia and incubation temperature on growth, differentiation, heart mass, and oxygen consumption in embryos of the leopard gecko (Eublepharis macularius)

Oviparous reptile embryos must tolerate fluctuations in oxygen availability and incubation temperature during development. In this study, regional hypoxia was simulated by painting eggs of Eublepharis macularius with melted paraffin wax to decrease the available surface area for gas exchange by approximately 80%. Experimental and control eggs were incubated at either 28 or 34 °C and embryo mass, stage, heart mass, relative heart mass, and oxygen consumption (V̇O2) were measured at 15 and 30 days of incubation. Embryo mass from the regional hypoxia treatment was reduced by about 50% at day 15 and by about 30% at day 30 of incubation, independent of incubation temperature compared to controls. Embryo stage from the regional hypoxia treatment was reduced by about 2 stages at day 15 independent of incubation temperature but there was no effect of hypoxia treatment at day 30. Absolute heart mass was reduced by about 60% in regional hypoxia embryos sampled at day 15 while relative heart mass was increased by about 30% in regional hypoxic embryos at day 30 compared to controls, suggesting that heart mass is conserved at the expense of somatic growth. Embryo V̇O2 was affected by incubation temperature at both 15 and 30 days of incubation but not by regional hypoxia treatment. These results indicate that embryos of E. macularius possess plasticity in their capacity to respond to reduction in oxygen availability during incubation, and are able to survive and continue developing when gas exchange surface area is severely limited.

Constitutive cardiomyocyte proliferation in the leopard gecko (Eublepharis macularius).

Although the contractile function of the heart is universally conserved, the organ itself varies in structure across species. This variation includes the number of ventricular chambers (one, two, or an incompletely divided chamber), the structure of the myocardial wall (compact or trabeculated), and the proliferative capacity of the resident cardiomyocytes. Whereas zebrafish are capable of comparatively high rates of constitutive cardiomyocyte proliferation, humans and rodents are not. However, for most species, the capacity to generate new cardiomyocytes under homeostatic conditions remains unclear. Here, we investigate cardiomyocyte proliferation in the lizard Eublepharis macularius, the leopard gecko. As for other lizards, the leopard gecko heart has a partially septated ventricular lumen with a trabeculated myocardial wall. To test our hypothesis that leopard gecko cardiomyocytes routinely proliferate, we performed 5-bromo-2'-deoxyuridine incorporation and immunostained for the mitotic marker phosphorylated histone H3 (pHH3) and the DNA synthesis phase (S phase) marker proliferating cell nuclear antigen (PCNA). Using double immunofluorescence, we co-localized pHH3 or PCNA with the cardiomyocyte marker myosin heavy chain (MHC). We found that ~0.5% of cardiomyocytes were mitotically active (pHH3+/MHC+), while ~10% were in S phase (PCNA+/MHC+). We also determined that cell cycling by gecko cardiomyocytes is not impacted by caudal autotomy (tail loss), a dramatic form of self-amputation. Finally, we show that populations of cardiac cells are slow cycling. Overall, our findings provide predictive evidence that geckos may be capable of spontaneous cardiac self-repair and regeneration following a direct injury.

Evidence for neurogenesis in the medial cortex of the leopard gecko, Eublepharis macularius

Although lizards are often described as having robust neurogenic abilities, only a handful of the more than 6300 species have been explored. Here, we provide the first evidence of homeostatic neurogenesis in the leopard gecko (Eublepharis macularius). We focused our study on the medial cortex, homologue of the mammalian hippocampal formation. Using immunostaining, we identified proliferating pools of neural stem/progenitor cells within the sulcus septomedialis, the pseudostratified ventricular zone adjacent to the medial cortex. Consistent with their identification as radial glia, these cells expressed SOX2, glial fibrillary acidic protein, and Vimentin, and demonstrated a radial morphology. Using a 5-bromo-2′-deoxyuridine cell tracking strategy, we determined that neuroblast migration from the ventricular zone to the medial cortex takes ~30-days, and that newly generated neuronal cells survived for at least 140-days. We also found that cell proliferation within the medial cortex was not significantly altered following rupture of the tail spinal cord (as a result of the naturally evolved process of caudal autotomy). We conclude that the sulcus septomedialis of the leopard gecko demonstrates all the hallmarks of a neurogenic niche.

Evaluation of β-carotene assimilation in leopard geckos (Eublepharis macularius).

Although leopard geckos (Eublepharis macularius) are commonly kept under human care, their vitamin requirements are largely unknown. Many invertebrate preys display a low vitamin A concentration; thus, gut-loading insects with vitamin A or carotenoids is a common practice. The objective of this prospective experimental study was to investigate whether dietary supplementation with β-carotene, including prey gut-loading, leads to sufficient vitamin A hepatic storage and prevents epithelial squamous metaplasia development in leopard geckos. Ten clinically healthy female leopard geckos were randomly divided in two groups with various supplementations: a group receiving vitamin A supplementation and a group receiving β-carotene. Insects were gut-loaded continuously with a supplement containing vitamin A or β-carotene, depending on the group. Oral supplementation with cod liver oil or carrot juice was administered weekly to each lizard from "vitamin A group" and "carotenoid group" respectively. After 10weeks of supplementation, surgical hepatic biopsies were obtained in three geckos of each group while the two remaining geckos were euthanized to undergo complete necropsy. Hepatic vitamin A concentration was determined for each lizard (n=10) by ultra-performance liquid chromatography. Histopathology revealed hepatocellular vacuolization and vitellogenic follicles in five females. Epithelial squamous metaplasia was not observed in any of the geckos. Hepatic vitamin A concentration was significantly higher in the carotenoid-supplemented group than in the vitamin A-supplemented group (p=0.03). Our results suggest that in leopard geckos, dietary supplementation with β-carotene allows sufficient vitamin A hepatic storage.

Patterns of growth in the presacral vertebral column of the leopard gecko (Eublepharis macularius).

Postnatal growth patterns within the vertebral column may be informative about body proportions and regionalization. We measured femur length, lengths of all pre-sacral vertebrae, and lengths of intervertebral spaces, from radiographs of a series of 21 Eublepharis macularius, raised under standard conditions and covering most of the ontogenetic body size range. Vertebrae were grouped into cervical, sternal, and dorsal compartments, and lengths of adjacent pairs of vertebrae were summed before analysis. Femur length was included as an index of body size. Principal component analysis of the variance-covariance matrix of these data was used to investigate scaling among them. PC1 explained 94.19% of total variance, interpreted as the variance due to body size. PC1 differed significantly from the hypothetical isometric vector, indicating overall allometry. The atlas and axis vertebrae displayed strong negative allometry; the remainder of the vertebral pairs exhibited weak negative allometry, isometry or positive allometry. PC1 explained a markedly smaller amount of variance for the vertebral pairs of the cervical compartment than for the remainder of the vertebral pairs, with the exception of the final pair. The relative standard deviations of the eigenvalues from the PCAs of the three vertebral compartments indicated that the vertebrae of the cervical compartment were less strongly integrated by scaling than were the sternal or dorsal vertebrae, which did not differ greatly between themselves in their strong integration, suggesting that the growth of the cervical vertebrae is constrained by the mechanical requirements of the head. Regionalization of the remainder of the vertebral column is less clearly defined but may be associated with wave form propagation incident upon locomotion, and by locomotory changes occasioned by tail autotomy and regeneration. Femur length exhibits negative allometry relative to individual vertebral pairs and to vertebral column length, suggesting a change in locomotor requirements over the ontogenetic size range.

INTRAVENOUS ALFAXALONE ANAESTHESIA IN LEOPARD GECKOS (EUBLEPHARIS MACULARIUS)

Intravenous alfaxalone, administered at a dose of 5mg/kg in the jugular vein, was evaluated in 20 leopard geckos (Eublepharis macularius) to ascertain its ability to provide anesthesia. The induction time, time to loss of mandibular tone, interval of deep anesthesia, and full recovery time were 27.5 ± 30.7seconds (10 to 56seconds), 1.3 ± 1.4minutes (11 seconds to 4 minutes), 12.5 ± 2.2minutes (11.11 to 15.39minutes), and 18.8 ± 12.1minutes (10.4 to 52.31minutes), respectively. A significant reduction in heart rate (74 ± 12.9 beats/minute) was recorded between 2 and 24minutes after alfaxalone administration. A significant decrease in respiratory rate (26.8 ± 10.1 breaths/minute) was recorded 2minutes after alfaxalone administration, and respiratory rate remained lower than the basal rate (31.4 ± 3.1 breaths/minute) for 24minutes but without statistical significance. The intravenous administration of alfaxalone in leopard geckos achieved a rapid onset of anesthesia and a suitable recovery time. Based on this investigation, an afaxalone dose of 5 mg/kg intravenously proved to be suitable for sedation before tracheal intubation. Moreover, the administration route via the jugular vein, was acceptable in leopard geckos; a species in which other venipuncture sites can be challenging or inaccessible.

Growth Factor Expression by Cardiac Tissues in the Leopard Gecko (Eublepharis macularius)

Tissue homeostasis is a dynamic process involved in the maintenance of tissue structure and function in response to physiological fluctuations in biochemistry, metabolism, and physical conditions. Despite the profound role that growth factors play in homeostasis of organs such as the heart, constitutive patterns of expression are only known for a handful of species. Here, we investigated growth factor expression in the heart of a representative reptile, the leopard gecko (Eublepharis macularius; hereafter, ‘gecko’). We focused our investigation on three major classes known to be expressed by mammalian cardiac tissues: transforming growth factor β (TGFβ); vascular endothelial growth factor A (VEGF); and basic fibroblast growth factor (FGF‐2). Similar to other squamates (snakes and lizards), geckos have a three‐chambered heart with two atria and one ventricle. The ventricular myocardium includes a trabeculated or spongy‐like inner compartment, and a thin, compact cortical layer. We determined that cardiac cells in both compartments of the gecko myocardium (trabeculated and compact) constitutively express a diverse panel of growth factor ligands and receptors commonly associated with wound healing and repair, including: TGFβ1, activin‐βA, and phosphorylated SMAD2; FGF‐2; and VEGF, VEGF receptor 1 (VEFGR1), VEGFR2, and phosphorylated VEGFR2. Using double immunofluorescence, we observed co‐localization of VEGF/VEGFR2 and VEGFR1/VEGFR2, indicating that – similar to mammals – reptilian cardiomyocytes may use paracrine and autocrine signalling. Taken together, these findings indicate a homeostatic role for these growth factors in the heart that is conserved across reptiles and mammals.Support or Funding InformationNatural Sciences and Engineering Research Council (NSERC) Discovery Grant 400358 (to MV); Ontario Veterinary College Scholarship (to KJ)This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Towards A Structural Characterization of The Leopard Gecko Cerebellum: Purkinje Cells And Cells of The External Granular Layer

The cerebellum is a major component of the hindbrain, and plays important roles in motor coordination, posture, and cognitive functions. Although the gross anatomy and histological organization of the cerebellum has been documented across many species, less is known about the contributing cell types, especially among non‐mammals. Here we focus on Purkinje cells (PC) and cells of the External Granular Layer (EGL) in a representative lizard, the leopard gecko (Eublepharis macularius). PC serve as the major motor output of the cerebellum. Similar to other vertebrates, gecko PC are large, calbindin‐immunopositive neurons located at the junction between the molecular layer and the granular layer. Golgi‐cox impregnation reveals a dendritic arborization broadly comparable with that of alligators (and distinct from that of mammals). There is typically a single, lengthy primary dendrite that passes towards the molecular layer. This primary dendrite divides into multiple short dendritic branches that conclude in thin spiny branchlets with abundant, closely packed spines. Adult geckos also retain an EGL, a progenitor cell population that characteristically disappears prior to adulthood in mammals. Cells of the gecko EGL are immunopositive for the transcription factor SOX2, a hallmark protein of neural stem/progenitor cells, and the intermediate filament (and radial glia marker) glial fibrillary acid protein, but are immunonegative for NeuN, a marker of mature neurons. Using a bromodeoxyuridine pulse‐chase strategy, we determined that a subset of gecko EGL cells were label retaining after a 140 day chase period. Combined, these data provide important new information about the evolutionary variability of the cerebellum, with implications for functional adaptations in a species capable of tail loss.Support or Funding InformationNatural Sciences and Engineering Research Council Discovery Grant #400358 (MKV), #436190 (CDCB) and The Canada Foundation for Innovation #25371 (MKV) and #30381 (CDCB)This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Radial Glia and Cell Heterogeneity Across The Lizard Central Nervous System: Distal Spinal Cord Rupture Does Not Induce a System‐Wide Response

Radial glia are resident neural stem/progenitor cells of the central nervous system of many non‐mammalian species. Radial glia are capable of spontaneously generating new neurons, and are considered to be crucial for both brain development and injury‐mediated regeneration. Recently, radial glia have also been identified in the tail spinal cord of the lizard Eublepharis macularius (the leopard gecko), a species capable of tail spinal cord regeneration. Here, we investigated whether similar populations of radial glia were present within the body spinal cord (bSC) and brain. Using a bromodeoxyuridine pulse‐chase strategy, we determined that label‐retaining cells were found throughout the bSC and the forebrain following a 20‐week chase. Next, we established that populations of cells lining the central canal (of the bSC) and ventricular system (of the brain) express a panel of radial glia markers, including the transcription factor SOX2 and the intermediate filaments GFAP and Vimentin. However, Vimentin expression was conspicuously absent from the diencephalon (except for the hypothalamic eminence), as well as the midbrain and hindbrain. Further, cell populations lining the central canal of the bSC include both radial glia and cells with a neuronal phenotype (as evidenced by expression of the neuronal marker HuCD). An identical diversity of cell types is also reported for in the regeneration‐competent tail spinal cord. Finally, we determined that constitutive proliferation by cells lining the central canal (of the bSC) and the ventricular system (of the forebrain) are essentially unaltered in response to distal central nervous system injury (tail spinal cord rupture as a result of tail loss). Combined, our data demonstrates that radial glia are present throughout the central nervous system of the gecko, that the bSC is essentially identical to that of the tail, and that the bSC and forebrain are resilient to distal spinal cord injuries.Support or Funding InformationNatural Sciences and Engineering Research Council Discovery Grant 400358 (MKV), Canadian Foundation for Innovation Leaders Opportunity Fund 25371(MKV)This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Female sexual attractiveness and sex recognition in leopard gecko: Males are indiscriminate courters

The nature and hormonal control of cues used for recognition of sex and reproductive status of conspecifics remain largely unstudied in reptiles. It has been proposed that production of a female attractiveness pheromone controlled by female ovarian hormones (and which is suppressed by male gonadal androgens) is necessary to elicit courtship in males. In the case of leopard gecko (Eublepharis macularius), it has been suggested that an individual is recognized as a male and attacked unless it produces female-specific stimuli in its skin and that females are attacked, not courted, while shedding. We tested the reactions of males to control males and control shedding and non-shedding females, castrated males, females treated with exogenous androgens (testosterone and dihydrotestosterone), and prepubertal individuals. The individuals with high androgen levels (i.e., control males and hormone-treated females) were attacked while animals in all the other groups were courted. Our results indicate that in leopard gecko hormonally controlled pheromones advertising female attractiveness are not required and that sex discrimination is based on the presence or absence of cues dependent on masculinization by male gonadal steroids.

Ultrasonographic anatomy of reproductive female leopard geckos (Eublepharis macularius).

Captive leopard geckos (Eublepharis macularius) often present to the exotic clinic for gastrointestinal impactions, follicular stasis, or dystocia. To our knowledge, normal ultrasonographic anatomy of these lizards has not been described. The objectives of this prospective, anatomic, analytical study were to develop ultrasound techniques for this species and to describe the normal sonographic anatomy of the head, coelomic cavity, and tail. Eleven, healthy, female leopard geckos were included. A linear array 13-18MHz transducer was used. Geckos were sedated and restrained in dorsal recumbency for coelomic structure examination and in ventral recumbency for head and tail examinations. Sagittal and transverse images were acquired and authors recorded qualitative and quantitative ultrasonographic characteristics of anatomic structures. The ventral surface of the lungs, liver, gallbladder, caudal vena cava, portal vein, ventral abdominal vein, aorta, ovarian follicles, fat bodies, tail, and brain were visualized in 10 of 11 individuals. In one individual, molt precluded ultrasonographic examination. The heart, kidneys, urinary bladder, spleen, and pancreas were not visualized. The digestive tract was observed in 10 individuals but was too small to be measured. Findings from the current study could be used as a reference for future studies of leopard geckos.

VEGF, FGF-2 and TGFβ expression in the normal and regenerating epidermis of geckos: implications for epidermal homeostasis and wound healing in reptiles.

The skin is a bilayered organ that serves as a key barrier between an organism and its environment. In addition to protecting against microbial invasion, physical trauma and environmental damage, skin participates in maintaining homeostasis. Skin is also capable of spontaneous self-repair following injury. These functions are mediated by numerous pleiotrophic growth factors, including members of the vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF), and transforming growth factor β (TGFβ) families. Although growth factor expression has been well documented in mammals, particularly during wound healing, for groups such as reptiles less is known. Here, we investigate the spatio-temporal pattern of expression of multiple growth factors in normal skin and following a full-thickness cutaneous injury in the representative lizard Eublepharis macularius, the leopard gecko. Unlike mammals, leopard geckos can heal cutaneous wounds without scarring. We demonstrate that before, during and after injury, keratinocytes of the epidermis express a diverse panel of growth factor ligands and receptors, including: VEGF, VEGFR1, VEGFR2, and phosphorylated VEGFR2; FGF-2 and FGFR1; and phosphorylated SMAD2, TGFβ1, and activin βA. Unexpectedly, only the tyrosine kinase receptors VEGFR1 and FGFR1 were dynamically expressed, and only during the earliest phases of re-epithelization; otherwise all the proteins of interest were constitutively present. We propose that the ubiquitous pattern of growth factor expression by keratinocytes is associated with various roles during tissue homeostasis, including protection against ultraviolet photodamage and coordinated body-wide skin shedding.

A comparative study of growth: different body weight trajectories in three species of the genus Eublepharis and their hybrids

An extensive research effort is devoted to the evolution of life-histories and processes underlying the variation in adult body weight; however, in this regard, some animal taxa remain neglected. Here we report rates and timing of growth recorded in two wild-derived populations of a model lizard species, Eublepharis macularius (M, W), other two related species, i.e., E. angramainyu (A) and E. sp. (D), and their between-species hybrids. We detected clear differences among the examined species/populations, which can be interpreted in the terms of “fast – slow” continuum of life-history strategies. The mean asymptotic body size was the highest in A and further decreased in the following order: M, W, and D. In contrast, the growth rate showed an opposite pattern. Counter-intuitively, the largest species exhibited the slowest growth rates. The final body size was determined mainly by the inflexion point. This parameter reflecting the duration of exponential growth increased with mean asymptotic body size and easily overcompensated the effect of decreasing growth rates in larger species. Compared to the parental species, the F1 and backcross hybrids exhibited intermediate values of growth parameters. Thus, except for the case of the F2 hybrid of MxA, we failed to detect deleterious effects of hybridization in these animals with temperature sex determination.

Diagnosis, treatment, and outcome of and risk factors for ophthalmic disease in leopard geckos (Eublepharis macularius) at a veterinary teaching hospital: 52 cases (1985-2013).

OBJECTIVE To describe diagnosis, treatment, and outcome of and risk factors for ophthalmic disease in leopard geckos (Eublepharis macularius) evaluated at a veterinary teaching hospital. DESIGN Retrospective case series. ANIMALS 112 of 144 (78%) leopard geckos that were evaluated at a veterinary teaching hospital in January 1985 through October 2013 and for which sufficient medical record information was available. PROCEDURES Information from medical records was used to identify leopard geckos with ophthalmic disease, characterize cases, and determine risk factors for the presence of ophthalmic disease. RESULTS Of the 112 leopard geckos, 52 (46%) had ophthalmic disease (mainly corneal or conjunctival disease). Female geckos were less likely to have ophthalmic disease, and there was a positive association between increasing age and ophthalmic disease. Use of a paper towel substrate, absence of any heat source, and lack of vitamin A supplementation were positively associated with a diagnosis of ophthalmic disease. Head dysecdysis was the only concurrent disorder significantly associated with ophthalmic disease. At necropsy, 5 affected leopard geckos had squamous metaplasia of the conjunctivae. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that ophthalmic disease is a common finding in leopard geckos. The cause of ocular surface disease in leopard geckos may be multifactorial, and hypovitaminosis A may be an important risk factor. Although animals receiving supplemental vitamin A were less likely to have ophthalmic disease, further understanding is required regarding the metabolism of and nutritional requirements for vitamin A in leopard geckos.

Evaluating the Physiologic Effects of Short Duration Ultraviolet B Radiation Exposure in Leopard Geckos (Eublepharis macularius)

Abstract Ultraviolet B radiation (UVB) is required by many vertebrates to stimulate the photobiochemical synthesis of vitamin D. Vitamin D plays many important roles in the body, including assisting in the absorption of calcium at the level of the intestines. Deficiencies in vitamin D can lead to the development of nutritional disease. Leopard geckos (Eublepharis macularius) are naturally nocturnal to crepuscular; therefore, it is not known whether they benefit from UVB radiation. The purpose of this study was to measure 25-hydroxyvitamin D3 concentrations in leopard geckos exposed to short duration UVB light. Twelve adult, male leopard geckos were used for this study. Blood samples were collected from the cranial vena cava to establish baseline 25-hydroxyvitamin D3 concentrations. Once the baseline samples were collected, the animals were randomly divided into two groups. The animals provided UVB radiation were exposed to non-UVB producing light for 12 h and UVB for 2 h, whereas animals in the control gr...

Encoding lateralization of jump kinematics and eye use in a locust via bio-robotic artifacts

The effect of previous exposure to lateral sensory stimuli in shaping the response to subsequent symmetric stimuli represents an important overlooked issue in neuroethology, with special reference to arthropods. In this research, we investigated the hypothesis to 'programme' jumping escape direction as well as surveillance orientation in young and adult individuals of Locusta migratoria as an adaptive consequence of prior exposure to directional-biased predator approaches generated by a robotic leopard gecko representing Eublepharis macularius The manipulation of the jumping escape direction was successfully achieved in young locusts, although young L. migratoria did not exhibit innately lateralized jumping escapes. Jumping escape direction was also successfully manipulated in adult locusts, which exhibited innate lateralized jumping escape at the individual level. The innate lateralization of each instar of L. migratoria in using a preferential eye during surveillance was not affected by prior lateralized exposure to the robotic gecko. Our results indicate a high plasticity of the escape motor outputs that are occurring almost in real time with the perceived stimuli, making them greatly adaptable and compliant to environmental changes in order to be effective and reliable. In addition, surveillance lateralization innately occurs at population level in each instar of L. migratoria Therefore, its low forgeability by environmental factors would avoid disorganization at swarm level and improve swarm coordination during group tasks. These findings are consistent with the fact that, as in vertebrates, in insects the right hemisphere is specialized in controlling fear and escape functions.

Neuromuscular control of locomotion is altered by tail autotomy in geckos.

Animal locomotion is driven by underlying axial and appendicular musculature. In order for locomotion to be effective, these muscles must be able to rapidly respond to changes in environmental and physiological demands. Although virtually unstudied, muscles must also respond to morphological changes, such as those that occur with tail autotomy in lizards. Tail autotomy in leopard geckos (Eublepharis macularius) results in a 25% loss of caudal mass and significant kinematic alterations to maintain stability. To elucidate how motor control of the locomotor muscles is modulated with these shifts, we used electromyography (EMG) to quantify patterns of in vivo muscle activity in forelimb and hindlimb muscles before and after autotomy. Forelimb muscles (biceps brachii and triceps brachii) exhibited no changes in motor recruitment, consistent with unaltered kinematics after autotomy. The amplitude of activity of propulsive muscles of the hindlimbs (caudofemoralis and gastrocnemius) was significantly reduced and coincided with decreases in the propulsive phases of femur retraction and ankle extension, respectively. The puboischiotibialis did not exhibit these changes, despite significant reductions in femur depression and knee angle, suggesting that the reduction in mass and vertical ground-reaction force by autotomy allows for the maintenance of a more sprawled and stable posture without increasing motor recruitment of the support muscles. These results highlight the significant neuromuscular shifts that occur to accommodate dramatic changes in body size and mass distribution, and illuminate the utility of tail autotomy as a system for studying the neuromuscular control of locomotion.

Wag the Lizard.

The article focuses on leopard geckos in the highlands of Afghanistan that possess self-amputation ability, called autotomy, which allows them to shed their tail when attacked, and a study by biologist Kevin Jagnandan and others on how the gecko adapts to losing its tail by taking sprawled posture.

Neural stem/progenitor cells are activated during tail regeneration in the leopard gecko (Eublepharis macularius).

As for many lizards, the leopard gecko (Eublepharis macularius) can self-detach its tail to avoid predation and then regenerate a replacement. The replacement tail includes a regenerated spinal cord with a simple morphology: an ependymal layer surrounded by nerve tracts. We hypothesized that cells within the ependymal layer of the original spinal cord include populations of neural stem/progenitor cells (NSPCs) that contribute to the regenerated spinal cord. Prior to tail loss, we performed a bromodeoxyuridine pulse-chase experiment and found that a subset of ependymal layer cells (ELCs) were label-retaining after a 140-day chase period. Next, we conducted a detailed spatiotemporal characterization of these cells before, during, and after tail regeneration. Our findings show that SOX2, a hallmark protein of NSPCs, is constitutively expressed by virtually all ELCs before, during, and after regeneration. We also found that during regeneration, ELCs express an expanded panel of NSPC and lineage-restricted progenitor cell markers, including MSI-1, SOX9, and TUJ1. Using electron microscopy, we determined that multiciliated, uniciliated, and biciliated cells are present, although the latter was only observed in regenerated spinal cords. Our results demonstrate that cells within the ependymal layer of the original, regenerating and fully regenerate spinal cord represent a heterogeneous population. These include radial glia comparable to Type E and Type B cells, and a neuronal-like population of cerebrospinal fluid-contacting cells. We propose that spinal cord regeneration in geckos represents a truncation of the restorative trajectory observed in some urodeles and teleosts, resulting in the formation of a structurally distinct replacement.

Ontogenetic allometry of the digital rays of the leopard gecko (Gekkota: Eublepharidae; Eublepharis macularius)

AbstractThe role of allometry in producing the variation in autopodial morphology observed among the lizards is not well understood. Allometry of metapodial and digit lengths in the manus and pes of the primitively padless gekkotan (Eublepharis macularius) is explored using maximum‐likelihood repeated‐measures ANCOVAs with body length as the covariate. Estimated variance–covariance matrices differed significantly within and between autopodia, and integration was stronger among the metapodials than the digits. The first metapodial and the first digit of each autopodium exhibit the strongest covariances with each of the remaining components in each variance–covariance matrix, suggesting that the lengths of the first rays are important for allometric integration of both manus and pes. Metapodials scale isometrically and digits negatively allometrically; both display allometric heterogeneity among themselves in both autopodia. Both autopodia exhibit changes in proportion over the ontogenetic size range, attributable to variation in scaling among the components of the rays. Allometric coefficients do not vary among pedal digits, despite differences in phalanx number, although phalanx number is associated with differences in slope in the manual digits. This is suggestive of heterogeneity in allometry among the manual phalanges, which thus may be associated with variation in phalanx length within gekkotan digits.