Morphology and Distribution of Cutaneous Sensory Organs on the Digits of Anolis carolinensis and A. sagrei (Squamata: Dactyloidae) in Relation to the Adhesive Toepads and Their Deployment

Cutaneous sensory organs are characteristic of many squamate lineages. Such organs may occur on the surface of scales as button-like, circular protuberances set off from their surroundings by a noticeable boundary, often taking the form of a moat or furrow. They may be relatively unadorned, clad with the surface micro-ornamentation of the scales on which they are carried, or they may carry one or more bristles of varying length and surface ornamentation. Such bristles may extend away from the body of the organ to interface with the surrounding environment or to contact adjacent scales. Cutaneous sensory organs have been physiologically demonstrated to have a mechanoreceptive function but have also been posited to potentially be involved with additional sensory modalities. Their distribution and structure across the body surface has been shown to be unequal, with some regions being much more extensively endowed than others, indicative of regional differential sensitivity. The digits of Anolis (Iguania: Dactyloidae) carry adhesive toepads that are convergent with those of geckos (Gekkota). Geckos exhibit a high density of cutaneous sensory organs on their toepads and their form and distribution has been associated with the operation and control of the toepads during locomotion. Investigation of the form and topographical distribution of cutaneous sensory organs on the toepads of Anolis shows them to be convergent in these attributes with those of geckos and quite distinct from those of the ancestrally padless Iguana (Iguania: Iguanidae). Their location at scale margins and the direction of their bristles towards adjacent scales indicates that the cutaneous sensory organs play an important role in proprioception during toepad deployment in Anolis.

Immunolocalization of the EDWM-Protein Indicates a Matrix Role in Cornification of Lizard Epidermis

During epidermal differentiation in the scales of lizards and snakes, from the basal layer beta- and later alpha-keratinocytes are generated to form beta-and alpha-corneous layers. In the lizard Anolis carolinensis, minor proteins derived from the EDC (Epidermal Differentiation Complex) are added to the main constituent proteins, IFKs (Intermediate Filament Keratins) and CBPs (Corneous Beta Proteins, formerly indicated as beta keratins). One of these proteins that previous studies showed to be exclusively expressed in the skin, EDWM (EDC protein containing high GSRC amino acids) is rich in cysteine and arginine, amino acids that form numerous –S–S– and electro-static chemical bonds in the corneous material. Light and electron microscopy immunolbeling for EDWM show a diffuse localization in differentiating beta-cells and in some alpha-cells, in particular those of the clear-layer, involved in epidermal shedding. The study suggests that EDWM may function as a matrix protein that binds to IFKs and CBPs, contributing to the formation of the specific corneous material present in beta- and alpha-corneous layers. In particular, its higher immunolocalization in the maturing clear layer indicates that this protein is important for its differentiation and epidermal shedding in A. carolinensis and likely also in other lepidosaurian reptiles.

Expression of insulin-like growth factors depends on both mass and resource availability in female green anoles (Anolis carolinensis)

The insulin and insulin-like signaling (IIS) network is an important mediator of cellular growth and metabolism in animals, and is sensitive to environmental conditions such as temperature and resource availability. The two main hormones of the IIS network, insulin-like growth factor 1 (IGF1) and insulin-like growth factor 2 (IGF2), are present in all vertebrates, yet little is known regarding the responsiveness of IGF2 in particular to external stimuli in non-mammalian animals. We manipulated diet (low quantity of food or high quantity of food) in adult green anole (Anolis carolinensis) females to test the effect of energetic state on hepatic gene expression of IGF1 and IGF2. The absolute expression of IGF2 in female green anoles is 100X higher than IGF1 regardless of diet treatment, and IGF1 and IGF2 expression interact with post-treatment body mass and treatment, as do the purported housekeeping genes glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and eukaryotic elongation factor 2 (EEF2). The Low Diet group showed a negative relationship between body mass and gene expression for all genes, whereas the relationships between body mass and gene expression in the High Diet group were either absent (in the case of IGF1) or positive (for all other genes). After accounting for total change in mass the Low Diet group expressed IGF2, GAPDH and EEF2 at higher levels compared to individuals in the High Diet group of similar ▵ mass. These results illustrate that expression of IGF1 and IGF2, and housekeeping genes are affected by energe­tic status in reptiles.

Green Anole lizards (Anolis carolinensis) deposit eggs in nests of the Trap Jaw Ant, Odontomachus brunneus

Squamates eggs are rarely found in ant nests, and are largely restricted to the nests of neotropical fungus gardening in the tribe Attini. Ponerine ant nests have not previously been reported as nesting cavities for squamates, including the Green Anole (Anolis carolinensis). The current study reports the association of Green Anole eggs and hatchlings with the subterranean nest chambers of the trap jaw ant, Odontomachus brunneus. Hatching rates suggest that O. brunneus nests may be used communally by multiple females, which partition spatial resources with other recently introduced Anolis species in their native range. This new nesting strategy is placed in the context of know associations between frogs, snakes, legless worm lizards and ants.

Routine handling does not lead to chronic stress in captive green anole (Anolis carolinensis)

Routine handling has been shown to affect stress levels in a variety of animal species. This could result in a general decrease in welfare and may confound the results of scientific experiments or observations on captive study animals. In reptiles, there seems to be variation in the effects of handling on stress levels. Furthermore, most studies on reptiles only look at the effect of handling in the short term. In this study we quantified the physiological and behavioural impact of being held, twice daily, for 1 min at a time over a three-week period on the green anole (Anolis carolinensis). Measurements were collected at the end of the three-week repeated handling period. Our results showed no effect of repeated handling on body mass, tail-base width, heterophil to lymphocyte ratios (H/L ratios), behaviour and faecal corticosterone metabolite (FCM) levels for both males and females in the experimental treatments ('handled', 'unhandled'). Our study animals did score very highly for several stress-indicating variables in the three weeks preceding the experiments — suggesting that they had experienced considerable stress during capture, transport and temporary housing in the pet store.