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Background: Veiled chameleon (Chamaeleo calyptratus) and panther chameleon (Furcifer pardalis) are two of the most popular pet chameleons, and consequently, these species are frequently evaluated in veterinary practices. According to our review of the literature, normal computed tomography (CT) anatomy of these lizards has not been previously described. Aim: The purposes of this prospective study were to describe the normal CT anatomy of the coelomic organs in healthy patients and to provide normal reference values in these species. Methods: Seventeen clinically healthy veiled chameleons and 15 clinically healthy panther chameleons were included. All CT studies were performed with the chameleons under light anesthesia and positioned in sternal recumbency. Studies were performed with a 16-slice helical CT scanner with a slice thickness of 0.625 mm. The authors recorded qualitative and quantitative CT characteristics of the coelomic structures. Macroscopic cross-sectional anatomy was performed for comparison of the CT findings. Results: Heart, lungs, liver, including caudal vena cava, hepatic vessels, gallbladder, esophagus, stomach, intestines, gonads, fat bodies, kidneys, and urinary bladder could be visualized with CT. The spleen, pancreas, and adrenal glands could not be identified. Conclusion: This study provides a guide to the normal cross-sectional and computed tomographic anatomy of the coelomic cavity in veiled and panther chameleons. Our results could be used as a reference for future research studies or comparison of clinically ill patients. [ABSTRACT FROM AUTHOR]

Recent evidence suggests that lizards of the family Chamaeleonidae are one of the most heavily parasitized groups of reptiles kept in captivity; however, little is known about the clinical implications of these infections. Relative to other host species, there is a paucity of information on reptile parasites and the breadth of parasites that infect chameleons is not well described. We report a parasitic infection most consistent with organisms belonging to the Mesomycetozoea group in male and female wild-caught jeweled chameleons (Furcifer campani). Clinical features of infection included persistent weight loss, despite increased food intake; cachexia; abnormally increased light- and heat-seeking behavior; coelomic distention; and loose, watery stools. Histologically, there was extensive granuloma formation present in the liver and widespread localization of periodic acid–Schiff- and Grocott's methenamine silver–positive spores resembling those of Dermocystidium sp. in the bone marrow, gastrointestinal tract, and other tissues. A second case of infection with this pathogen also presented with concurrent Mycobacterium sp. throughout the body, suggesting that infection with mesomycetozoean organisms may serve as a primary cause of death, or conversely, may render the infected individual susceptible to secondary, opportunistic infection. The rapid health decline associated with infection in these cases indicates a need to better characterize prevalence and pathogenicity of parasites in captive chameleons. [ABSTRACT FROM AUTHOR]

It is argued that Tertullian's relatively lengthy description of a chameleon in his De pallio serves as a metaphor not so much for the convert to a philosophical way of life in general but for the convert to Christianity in particular. The argument rests on the unusual emphases within this description which recall different features of Christianity or popular beliefs about the same. [ABSTRACT FROM AUTHOR]

In this paper, we explore the homogeneous and isotropic flat Friedmann–Robertson–Walker (FRW) model in Chameleon cosmology. By considering a non-minimal coupling between the scalar field and matter, we present a non-singular bouncing cosmological scenario of the universe. The universe initially exhibits the ekpyrotic phase during the contracting era, undergoes a non-singular bounce, and then in expanding era, it smoothly transits to the decelerating era having matter and radiation-dominated phases. Further, this decelerating era is smoothly connected to the late-time dark energy-dominated era of the present epoch. We use numerical solution techniques to solve non-minimally coupled gravity equations for understanding the evolution of scalar field along with other quantities like effective potential in the model. The model thus unifies an ekpyrotic, non-singular, asymmetric bounce with the dark energy era of the present epoch. We study the evolution of bouncing model and confront the model with observational results on the equation of state parameter by constraining the model parameters. [ABSTRACT FROM AUTHOR]

Questions: Most clustering methods assume data are structured as discrete hyperspheroidal clusters to be evaluated by measures of central tendency. If vegetation data do not conform to this model, then vegetation data may be clustered incorrectly. What are the implications for cluster stability and evaluation if clusters are of irregular shape or density? Location: Southeast Australia. Methods: We define misplacement as the placement of a sample in a cluster other than (distinct from) its nearest neighbor and hypothesize that optimizing homogeneity incurs the cost of higher rates of misplacement. Chameleon is a graph‐theoretic algorithm that emphasizes interconnectivity and thus is sensitive to the shape and distribution of clusters. We contrasted its solutions with those of traditional nonhierarchical and hierarchical (agglomerative and divisive) approaches. Results: Chameleon‐derived solutions had lower rates of misplacement and only marginally higher heterogeneity than those of k‐means in the range of 15–60 clusters, but their metrics converged with larger numbers of clusters. Solutions derived by agglomerative clustering had the best metrics (and divisive clustering the worst) but both produced inferior high‐level solutions to those of Chameleon by merging distantly‐related clusters. Conclusions: Graph‐theoretic algorithms, such as Chameleon, have an advantage over traditional algorithms when data exhibit discontinuities and variable structure, typically producing more stable solutions (due to lower rates of misplacement) but scoring lower on traditional metrics of central tendency. Advantages are less obvious in the partitioning of data from continuous gradients; however, graph‐based partitioning protocols facilitate the hierarchical integration of solutions. [ABSTRACT FROM AUTHOR]

Background: Squamate reptiles (lizards, snakes, and amphisbaenians) exhibit incredible diversity in their locomotion, behavior, morphology, and ecological breadth. Although they often are used as models of locomotor diversity, surprisingly little attention has been given to muscle development in squamate reptiles. In fact, the most detailed examination was conducted almost 80 years ago and solely focused on the proximal limb regions. Herein, we present forelimb and hindlimb muscle morphogenesis data for three lizard species with different locomotion and feeding strategies: the desert grassland whiptail lizard, the central bearded dragon, and the veiled chameleon. This study fills critical gaps in our understanding of muscle morphogenesis in squamate reptiles and presents a comparative and temporospatial analysis of muscle development. Results: Our results reveal a conserved pattern of early muscle development among lizards with different adult morphologies and ecologies. The variations that exist are concentrated in distal regions, particularly the specialized autopodia of chameleons, where differentiation of muscles associated with the digits is delayed. Conclusions: The chameleon autopod provides an example of major evolutionary modifications to the skeleton with only minor disruption of the conserved order and pattern of limb muscle development. This robustness of muscle patterning facilitates the evolution of extreme yet functional phenotypes. Key Findings: First complete description of forelimb and hindlimb muscle morphogenesis for lizards (Squamata).Muscle cleavage in the chameleon autopodia is delayed relative to generalized lizards.Zygodactyly in chameleons and birds forms through different mechanisms. [ABSTRACT FROM AUTHOR]

A 4-yr-old, captive-bred, male veiled chameleon (Chamaeleo calyptratus) presented with anorexia, weight loss, and stomatitis. Complete blood count revealed pancytopenia and a marked leukocytosis (197 × 103/µL) composed of blast cells (195 × 103/µL) that had oval to irregular nuclei with finely stippled chromatin and occasional nucleoli. The diagnosis was acute leukemia of presumptive myeloid origin. Treatment with prednisone (1.5 mg/kg once daily orally) and cytosine arabinoside (300 mg/m2 subcutaneously) was initiated. Post treatment hematologic analysis revealed decreased blast count (88.5 × 103/µL) and improved mentation. Additional doses of cytosine arabinoside were given 2 and 3 wk after the initial diagnosis with marked improvement in circulating blast concentration (15.3 × 103/µL). During the course of treatment, which included the chemotherapeutics, fluid therapy, and oral supportive care, the chameleon's weight increased 32.5% (199–295 g). Unfortunately, the animal died 33 days after presentation. Histopathologic evaluation revealed hypocellular bone marrow with rare, blast-like cells within vessels and mycotic granulomatous hepatitis with intralesional hyphae and fructiferous bodies. The blast cells expressed Iba1 but not CD3, CD79a, or lysozyme, suggesting a myeloid origin. Cell morphology further reinforced an acute myeloid leukemia. The authors surmised that the chameleon was responding to treatment, but ultimately succumbed to the mycotic hepatitis. This report describes the first case of acute myeloid leukemia with response to chemotherapeutic intervention in a veiled chameleon. [ABSTRACT FROM AUTHOR]

Background: Pronounced asymmetric changes in ocular globe size during eye development have been observed in a number of species ranging from humans to lizards. In contrast, largely symmetric changes in globe size have been described for other species like rodents. We propose that asymmetric changes in the three‐dimensional structure of the developing eye correlate with the types of retinal remodeling needed to produce areas of high photoreceptor density. To test this idea, we systematically examined three‐dimensional aspects of globe size as a function of eye development in the bifoveated brown anole, Anolis sagrei. Results: During embryonic development, the anole eye undergoes dynamic changes in ocular shape. Initially spherical, the eye elongates in the presumptive foveal regions of the retina and then proceeds through a period of retraction that returns the eye to its spherical shape. During this period of retraction, pit formation and photoreceptor cell packing are observed. We found a similar pattern of elongation and retraction associated with the single fovea of the veiled chameleon, Chamaeleo calyptratus. Conclusions: These results, together with those reported for other foveated species, support the idea that areas of high photoreceptor packing occur in regions where the ocular globe asymmetrically elongates and retracts during development. Key Findings: The eyes of the brown anole, Anolis sagrei, and veiled chameleon, Chamaeleo calyptratus undergo dynamic asymmetrical changes in ocular shape during development.In both species, asymmetric elongation and retraction of the ocular globe is associated with fovea morphogenesis.Pit formation and photoreceptor cell packing in the foveal area occur when the corresponding region of the ocular globe is retracting relative to adjacent regions. [ABSTRACT FROM AUTHOR]

Intracellular epidermal inclusions were detected within histological sections of skin biopsies from two panther chameleons (Furcifer pardalis) with chronic cheilitis. Transmission electron microscopy (TEM) confirmed the abundant presence of icosahedral intracytoplasmic and intranuclear viral particles in infected keratinocytes, with an average diameter of 120–125 nm, consistent with herpesviruses (HVs). TEM also revealed the presence of virions in intercellular spaces and keratinocyte nuclei and features suggestive of capsid assembly, nuclear egress with primary envelopment and anterograde transport leading to virion assembly and release. Polymerase chain reaction (PCR) primers targeting a conserved region of herpesvirus DNA-dependent DNA polymerase were used to amplify and sequence a product from a nested HV PCR performed on skin biopsies of both chameleons. Comparative sequence analysis indicates that the virus detected in both chameleons was a novel member of the Alphaherpesvirinae , which we refer to as chamaeleonid herpesvirus 1 (chamHV 1). Based on the identical findings in both chameleons, we consider chamHV 1 to be a candidate aetiological agent of cheilitis in panther chameleons. This is the first report of skin lesions in a chameleon species associated with HV infection. Image 1 [ABSTRACT FROM AUTHOR]

Chameleons (Chamaeleonidae, Reptilia) are known for their extreme sensory and motor adaptations to arboreal life and insectivoury. They show most distinct sequences of visuo-motor patterns in threat avoidance and in predation with prey capture being performed by tongue strikes that are unparalleled in vertebrates. Optical adaptations result in retinal image enlargement and the unique capacity to determine target distance by accommodation cues. Ocular adaptations result in complex eye movements that are context dependent, not independent, as observed in threat avoidance and predation. In predation, evidence from the chameleons' capacity to track multiple targets support the view that their eyes are under individual controls. Eye movements and body movements are lateralised, with lateralisation being a function of many factors at the population, individual, and specific-situation levels. Chameleons are considered a potentially important model for vision in non-mammalian vertebrates. They provide exceptional behavioural tools for studying eye movements as well as information gathering and analysis. They open the field of lateralisation, decision making, and context dependence. Finally, chameleons allow a deeper examination of the relationships between their unique visuo-motor capacities and the central nervous system of reptiles and ectotherms, in general, as compared with mammals. [ABSTRACT FROM AUTHOR]

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• Inspired by chameleon, dynamic fluorescent patterns were successfully achieved. • By facilely controlling the excitations, the dynamically display was demonstrated. • Flexible information encryption and information decryption was achieved. • Micro-sized patterns were fabricated by femtosecond laser-induced forward transfer. Chameleon can display variable body color/patterns under environmental stimulation via bioelectricity-controlled three layers of pigment cells and photonic crystals in the chameleon's skin. Inspired by color variation of chameleon, numerous "smart skins" have been achieved successfully, which possess great potential for optical information record and security. However, it remains challenging to produce full color dynamic fluorescent patterns with higher precision and flexibility to improve information capacity and anti-counterfeiting property. In this work, the micro-sized full color dynamic fluorescent patterns were successfully achieved by multiple transferring different colored quantum dots (QDs) from the carrier substrates to the receiving substrate via femtosecond laser-induced forward transfer (FsLIFT) technology using the chameleon skin as a prototype. The ability to dynamically display by facilely controlling the excitations is demonstrated, ensuring the information transformation function as chameleon skin. The resulting dynamic fluorescent patterns provide dual biomimetic of chameleon skin morphology and function. To illustrate the promising practical applications, flexible information encryption and information decryption relying on portable devices based on the fabricated dynamic fluorescent patterns have been achieved. It is anticipated that this bioinspired strategy is universal and promising for fabricating on-demand fluorescent dynamic patterns. [ABSTRACT FROM AUTHOR]

Lizards in the family Chamaeleonidae have been described as wiping a viscous substance from a pouch (the temporal pouch) at the angle of the jaw on branches and then capturing flies that land near the area where the wiping occurs. We confirmed the presence of this pouch in Jackson's chameleons. Histological work suggested that the material contained within is a result of decomposition of food and sloughed skin that has been trapped in the pouch rather than a glandular secretion. Gas chromatography-mass spectrometry indicated the presence of compounds that are both volatile and odiferous and similar to insect pheromones. Choice tests with houseflies revealed attraction to the temporal pouch material. Some authors have speculated that the temporal pouchmaterial serves a function in territory marking and/or predator deterrence. While it may play these roles, our results suggest that it also plays a role in chemical luring of prey. [ABSTRACT FROM AUTHOR]

Calumma vatosoa is a Malagasy chameleon species that has until now been known only from the male holotype and a photograph of an additional male specimen. In this paper we describe females of the chameleon Calumma vatosoa for the first time, as well as the skull osteology of this species. The analysed females were collected many years before the description of C. vatosoa, and were originally described as female C. linotum. According to external morphology, osteology, and distribution these specimens are assigned to C. vatosoa. Furthermore we discuss the species group assignment of C. vatosoa and transfer it from the C. furcifer group to the C. nasutum group. A comparison of the external morphology of species of both groups revealed that C. vatosoa has a relatively shorter distance from the anterior margin of the orbit to the snout tip, more heterogeneous scalation at the lower arm, a significantly lower number of supralabial and infralabial scales, and a relatively longer tail than the members of the C. furcifer group. These characters are, however, in line with the species of the C. nasutum group. In addition the systematic position of C. peyrierasi also discussed, based on its morphology. [ABSTRACT FROM AUTHOR]

The striking morphological convergence of hair-like integumentary derivatives of lizards and arthropods (spiders and insects) demonstrates the importance of such features for enhancing purchase on the locomotor substrate. These pilose structures are responsible for the unique tractive abilities of these groups of animals, enabling themtomove with seeming ease on overhanging and inverted surfaces, and to traverse inclined smooth substrates. Three groups of lizards are well known for bearing adhesion-promoting setae on their digits: geckos, anoles and skinks. Similar features are also found on the ventral subdigital and distal caudal skin of chameleons. These have only recently been described in any detail, and structurally and functionally aremuch lesswell understood than are the setae of geckos and anoles. The seta-like structures of chameleons are not branched (a characteristic of many geckos), nor do they terminate in spatulate tips (which is characteristic of geckos, anoles and skinks). They are densely packed and have attenuated blunt, globose tips or broad, blade-like shafts that are flattened for much of their length. Using a force transducer, we tested the hypothesis that these structures enhance friction and demonstrate that the pilose skin has a greater frictional coefficient than does the smooth skin of these animals. Our results are consistent with friction being generated as a result of side contact of the integumentary filaments. We discuss the evolutionary and functional implications of these seta-like structures in comparison with those typical of other lizard groups and with the properties of seta-mimicking synthetic structures. [ABSTRACT FROM AUTHOR]

Recently, we found dramatic mitochondrial DNA divergence of Israeli Chamaeleo chamaeleon populations into two geographically distinct groups. We aimed to examine whether the same pattern of divergence could be found in nuclear genes. However, no genomic resource is available for any chameleon species. Here we present the first chameleon transcriptome, obtained using deep sequencing (SOLiD). Our analysis identified 164,000 sequence contigs of which 19,000 yielded unique BlastX hits. To test the efficacy of our sequencing effort, we examined whether the chameleon and other available reptilian transcriptomes harbored complete sets of genes comprising known biochemical pathways, focusing on the nDNA-encoded oxidative phosphorylation (OXPHOS) genes as a model. As a reference for the screen, we used the human 86 (including isoforms) known structural nDNA-encoded OXPHOS subunits. Analysis of 34 publicly available vertebrate transcriptomes revealed orthologs for most human OXPHOS genes. However, OXPHOS subunit COX8 (Cytochrome C oxidase subunit 8), including all its known isoforms, was consistently absent in transcriptomes of iguanian lizards, implying loss of this subunit during the radiation of this suborder. The lack of COX8 in the suborder Iguania is intriguing, since it is important for cellular respiration and ATP production. Our sequencing effort added a new resource for comparative genomic studies, and shed new light on the evolutionary dynamics of the OXPHOS system. [ABSTRACT FROM PUBLISHER]

We analyse the phenomenology of a self-interacting scalar field in the context of the chameleon scenario originally proposed by Khoury and Weltman. In the absence of self-interactions, this type of scalar field can mediate long range interactions and simultaneously evade constraints from violation of the weak equivalence principle. By applying to such a scalar field the effective field theory method proposed for Einstein gravity by Goldberger and Rothstein, we give a thorough perturbative evaluation of the importance of non-derivative self-interactions in determining the strength of the chameleon mediated force in the case of orbital motion. The self-interactions are potentially dangerous as they can change the long range behaviour of the field. Nevertheless, we show that they do not lead to any dramatic phenomenological consequence with respect to the linear case and solar system constraints are fulfilled. [ABSTRACT FROM AUTHOR]

Information on the distribution and abundance of chameleons in Madagascar is required to develop conservation plans that integrate protected area management and sustainable use. We surveyed chameleons in eight sites in deciduous forest in Menabe, western Madagascar. Brookesia brygooi was the most frequently detected species, with a population density of 35 ha–1. Furcifer species were less common, with calculated densities of 7.2 ha–1 (F. labordi), 3.0 ha–1 (Furcifer sp.) and 1.3 ha–1 (F. oustaleti). Chameleon abundance varied according to altitude (B. brygooi) and no clear effect from logging was detected (all species). A lack of information on chameleon diurnal habitat requirements impedes a fuller assessment of the extent to which these species are tolerant to forest degradation. There were interspecific differences in the height of nocturnal perches and additional studies are needed to determine whether these are related to diurnal resource partitioning. Furcifer labordi and Furcifer sp. are of conservation concern because they are restricted to native forests in western Madagascar. [ABSTRACT FROM AUTHOR]

Glucocorticoids act throughout life to regulate numerous physiological and behavioral processes. Their levels are therefore highly labile, reacting to varying conditions and stressors. Hence, measuring glucocorticoids (and other steroids) in wildlife is challenging, and devising methods that are unaffected by the stress of capture and handling should be explored. Here we use the tip of free-ranging chameleons’ claws that were cut to allow individual identification, and report a steroids extraction and quantification method. Claw steroids present an integrated level representing the period of claw growth. We found that we could measure corticosterone in small amounts of chameleon claw matrix using commercial EIA kits. Using this method, we learned that in wild male chameleons, claw corticosterone levels were associated with body size. We suggest that claw-testing can potentially provide an ideal matrix for wildlife biomonitoring. [ABSTRACT FROM AUTHOR]

Signaling plays a critical role in social behavior, particularly in polygynous systems where males compete with rival males and use signals to attract mates. We quantified visual signals and social behavior in two previously unstudied species of chameleons in Madagascar, Furcifer labordi and F. verrucosus. Females of both species displayed distinct color patterns that signaled either nonreceptivity or potential sexual receptivity. Nonreceptive females rejected all male courtship. Potentially receptive F. verrucosus females mainly allowed males to attempt copulation, whereas potentially receptive F. labordi females were selective. We found that the fleshy, paddle-like rostral appendage in F. labordi was used only during courtship, whereas other studies showed that hard, keratinized appendages were used for male combat. During male-male contests, F. labordi had much more physically intense encounters, possibly to assess opponent quality more accurately since adult male F. labordi were significantly more size-matched than adult male F. verrucosus. Our study elucidated the role of social signals in these species, illustrated the atypical social behavior of chameleons compared to other lizards, and provided testable hypotheses to further delineate sexual selection in this understudied group. Sexual selection, especially intersexual selection, appears more likely in F. labordi than in F. verrucosus. [ABSTRACT FROM AUTHOR]

Null-model analysis of co-occurrence patterns is a powerful tool to identify ‘structure’ in community ecology data sets. We evaluated the community structure of chameleons in rainforest regions of Nigeria and Cameroon using available data in the literature, including peer-reviewed articles and unpublished environmental reports to industries. We performed Monte Carlo simulations (5000 iterations, using the sequential swap algorithm) under several model assumptions to derive co-occurrence patterns among species. Food and spatial (habitat) segregation patterns in both lowland rainforest and montane forest were investigated. We subjected four indices of co-occurrence patterns (C-ratio, number of checkerboard species pairs, number of species combinations, and V-score) to randomization procedures. Overall, the chameleon communities do not show random organization, but instead exhibit precise deterministic patterns. In lowland rainforest, chameleon communities are assembled deterministically along the food niche resource axis, but not along the habitat niche resource axis. The opposite holds for chameleon communities in montane rainforest. We predict that these patterns can be generalized to other regions of tropical Africa, thus helping to determine the general structure of chameleon communities in tropical African forests. [ABSTRACT FROM AUTHOR]

Madagascar's Brookesia dwarf chameleons are believed to require relatively intact forest for survival. Although they have featured in herpetological surveys, taxonomic reviews and trade assessments, very little is known about their microhabitat requirements or ecology. Over a 5 night period in a deciduous forest in western Madagascar we recorded the night roosting sites for three sympatric Brookesia species. We calculated the area and distance between successive night roost locations and described the characteristics of each roost. Distance between roosts and the area used were larger for B. brygooi and B. perarmata than B. exarmata. The distance between roosts was significantly greater for male than female B. brygooi and B. perarmata. Roost sites were generally in low vegetation (<0.75 m) with the animals located on stems or leaves. Roost height differed significantly between the species, with B. brygooi using the highest perches and B. exarmata the lowest. [ABSTRACT FROM AUTHOR]

We quantified habitat associations and evaluated the conservation status of a recently identified, undescribed species of dwarf chameleon, Bradypodion sp. nov. Dhlinza, endemic to scarp forest remnants in KwaZulu-Natal Province, South Africa. At the micro- habitat scale the Dhlinza dwarf chameleon was found more often in forest gaps and near paths than highly disturbed edges or forest interior. Chameleon presence was not explained by forest physiognomic variables such as vine cover, shrub and tree density, or canopy cover. Presence near gaps may be better explained by the combined effects of the thermal microenvironment and food availability. The species is moderately common where it occurs, with estimated densities of 4.7, 8.7 and 29.7 individuals per ha within forest interior, edges and gaps respectively. At the landscape scale, the chameleon occurs only in three remnant forests: the Dhlinza, Entumeni and Ongoye Forests. The species' extent of occurrence was estimated to be 88 km² and its area of occupancy 49 km². Based on the small area of remaining suitable habitat, this species meets the requirements for categorization as Endangered according to IUCN Red List criteria. [ABSTRACT FROM AUTHOR]

Visual pigments, oil droplets and photoreceptor types in the retinas of four species of true chameleons have been examined by microspectrophotometry. The species occupy different photic environments: two species of Chamaeleo are from Madagascar and two species of Furcifer are from Africa and the Arabian Peninsula. In addition to double cones, four spectrally distinct classes of single cone were identified. No rod photoreceptors were observed. The visual pigments appear to be mixtures of rhodopsins and porphyropsins. Double cones contained a pale oil droplet in the principle member and both outer segments contained a long-wave-sensitive visual pigment with a spectral maximum between about 555 nm and 610 nm, depending on the rhodopsin/porphyropsin mixture. Long-wave-sensitive single cones contained a visual pigment spectrally identical to the double cones, but combined with a yellow oil droplet. The other three classes of single cone contained visual pigments with maxima at about 480–505, 440–450 and 375–385 nm, combined with yellow, clear and transparent oil droplets respectively. The latter two classes were sparsely distributed. The transmission of the lens and cornea of C. dilepis was measured and found to be transparent throughout the visible and near ultraviolet, with a cut off at about 350 nm. [ABSTRACT FROM AUTHOR]

Apart from the pioneering studies of Ramon y Cajal [1893] and Rochon-Duvigneaud [1943], few studies have been devoted to the detailed study of the cytological and biochemical structure of the chameleon retina. In the present study we analyzed the expression of calbindin (CB), calretinin (CR) and parvalbumin (PV) immunoreactivities in the chameleon retina, and compared their distribution with those found in the retinas of other vertebrate species. CB immunoreactivity is dense in photoreceptors, horizontal and some lower amacrine cells. The most intense immunoreactivity was observed for calretinin; CR-ir amacrine cells are distributed throughout the inner nuclear, inner plexiform, and ganglion cell layers of the retina. Horizontal cells also display immunoreactivity to CR. A few retinal interneurons are weakly PV-ir. Double-labeling shows that all PV-ir or CB-ir cells, except the photoreceptors, are also strongly CR-ir. The distributions of these calcium-binding proteins in the chameleon retina share similarities with those observed in mammalian and avian retinas. In addition, the widespread distribution and co-localization of CB and CR reinforces the idea that these proteins play a general role in buffering the intracellular calcium levels in retinal cells. Furthermore, CB- and CR-immunoreactivities have enabled us to identify for the first time axon-bearing horizontal cells in the peripheral retina of the chameleon, very similar to those described in mammals. Copyright © 2005 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Abstract: Field active and laboratory preferred body temperatures and critical thermal limits were measured in six species of Kenyan chameleons: Chamaeleo bitaeniatus, Chamaeleo dilepis, Chamaeleo ellioti, Chamaeleo hohnelii, Chamaeleo jacksonii, and Chamaeleo schubotzi. Given the opportunity, all six species are very competent heliothermic thermoregulators. Individuals typically spend the night low in shrubby vegetation with body temperatures equal to ambient air, and then climb to the top or edges of their bushes to bask when the sun shines. For most species, body temperatures quickly stabilize between 29 and 32 °C, which they maintain while the sun shines (except C. schubotzi at 19 °C). Preferred temperatures in the laboratory average 30–33 °C, with voluntary minima of 27–29 °C and voluntary maxima of 34–36 °C. From the elaborate suite of behaviors undertaken and the distribution of environmental temperatures, it is clear that when solar radiation is available, these chameleon species do not passively accept environmental temperatures. Rather they regulate their body temperatures in the field, utilizing many of the behaviors that have become classically associated with heliothermic behavioral thermoregulation. All other chameleon species previously studied also have thermal preferenda around 30 °C. [Copyright &y& Elsevier]

The global trade in chameleons from 1977 to 2001 is reviewed using the compiled import data for chameleons from the CITES database. African countries accounted for 96% of reported exports, with Madagascar, Tanzanaia and Togo dominating the trade, while the USA dominated the import market with 69% of individuals. Chamaeleo senegalensis accounted for 25% of exports; only eight of the other 96 exported species each contributed more than 3% of the total 845,000 recorded exports. High exports in the late 1970s declined, with the exit of Kenya from the trade, to approximately 3000 individuals in 1982, before rising again to record exports of 81,000 individuals in 2001. Reported captive bred and ranched individuals form a small but increasing contribution to the trade. Contributions of individual countries to the changing pattern of trade are discussed in relation to governance issues. While national and international legislation has been successful in regulating the reported exports from the dominant exporting nations in the 1990s, the continuing rise in demand has led to that demand being satisfied by an increase in exports from other countries and, in particular, Uganda, Benin, Mozambique, Yemen and Comoros. [Copyright &y& Elsevier]

We investigated gaze-stabilizing reflexes in the chameleon using the three-dimensional search-coil technique. Animals were rotated sinusoidally around an earth-vertical axis under head-fixed and head-free conditions, in the dark and in the light. Gain, phase and the influence of eye position on vestibulo-ocular reflex rotation axes were studied. During head-restrained stimulation in the dark, vestibulo-ocular reflex gaze gains were low (0.1–0.3) and phase lead decreased with increasing frequencies (from 100° at 0.04 Hz to <30° at 1 Hz). Gaze gains were larger during stimulation in the light (0.1–0.8) with a smaller phase lead (<30°) and were close to unity during the head-free conditions (around 0.6 in the dark, around 0.8 in the light) with small phase leads. These results confirm earlier findings that chameleons have a low vestibulo-ocular reflex gain during head-fixed conditions and stimulation in the dark and higher gains during head-free stimulation in the light. Vestibulo-ocular reflex eye rotation axes were roughly aligned with the head's rotation axis and did not systematically tilt when the animals were looking eccentrically, up- or downward (as predicted by Listing's Law). Therefore, vestibulo-ocular reflex responses in the chameleon follow a strategy, which optimally stabilizes the entire retinal images, a result previously found in non-human primates. [ABSTRACT FROM AUTHOR]

The movements of both eyes and the head were recorded with search coils in unrestrained, freely moving chameleons. As a main result I found that the generation of saccades in the left and the right eye was either independent from each other or was highly correlated according to the behavioural situation. When no prey item was fixated, disconjugate saccades were observed which was in accordance with earlier observations in chameleons. During prey tracking the chameleons switched to a different oculomotor behaviour and pursued the moving prey with synchronous saccades. At higher target velocities, the tracking movement of the head was also saccadic and was synchronised with the two eyes. Binocular coupling affected only the timing of the saccades but not the metrics: the amplitudes of the synchronous saccades were usually different in the two eyes. These observations suggest the existence of two independent premotor neuronal circuits for left and right eye saccadic motor control in the chameleon. Binocular coupling in prey-tracking chameleons is probably achieved by neuronal coupling of these premotor circuits during eye–head coordination. The ability to switch between synchronous and uncoupled saccadic eye movements has not been described for any other vertebrate. This unique ability of the chameleon may help to understand the organisation of the oculomotor system of other vertebrates since evidence for separate left eye and right eye saccade generation and position control has recently also been reported in primates. [ABSTRACT FROM AUTHOR]

Malagasy chameleons are threatened by the relentless pace of habitat destruction. Their great popularity amongst herpetoculturalists has also resulted in collection for international animal markets. Most previous fieldwork has focused on the compilation of much needed species inventories, but little attention has been given to estimating chameleon population densities. This lack of information prevents a reliable assessment of the effects of habitat loss and direct exploitation on wild populations. A simple and repeatable methodology for the monitoring of chameleon populations is therefore urgently required. The present study developed survey techniques based on distance sampling within an area of relatively undisturbed rain forest at Ranomafana National Park. In total 394 individuals from six species were recorded and population densities (±SE) of 27.2±5.4/ha Brookesia spp. and 21.4±4.0/ha Calumma spp. were estimated using the computer program distance. The authors propose that monitoring of chameleons in areas subject to different threats should begin immediately using the methods outlined in this paper. [ABSTRACT FROM AUTHOR]

Serpentoviruses are an emerging group of nidoviruses known to cause respiratory disease in snakes and have been associated with disease in other non-avian reptile species (lizards and turtles). This study describes multiple episodes of respiratory disease-associated mortalities in a collection of juvenile veiled chameleons (Chamaeleo calyptratus). Histopathologic lesions included rhinitis and interstitial pneumonia with epithelial proliferation and abundant mucus. Metagenomic sequencing detected coinfection with two novel serpentoviruses and a novel orthoreovirus. Veiled chameleon serpentoviruses are most closely related to serpentoviruses identified in snakes, lizards, and turtles (approximately 40–50% nucleotide and amino acid identity of ORF1b). Veiled chameleon orthoreovirus is most closely related to reptilian orthoreoviruses identified in snakes (approximately 80–90% nucleotide and amino acid identity of the RNA-dependent RNA polymerase). A high prevalence of serpentovirus infection (>80%) was found in clinically healthy subadult and adult veiled chameleons, suggesting the potential for chronic subclinical carriers. Juvenile veiled chameleons typically exhibited a more rapid progression compared to subadults and adults, indicating a possible age association with morbidity and mortality. This is the first description of a serpentovirus infection in any chameleon species. A causal relationship between serpentovirus infection and respiratory disease in chameleons is suspected. The significance of orthoreovirus coinfection remains unknown. [ABSTRACT FROM AUTHOR]