Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Lizards”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 505 records · Page 28Linked to original sources
PubMed2006

Diet and foraging of the endemic lizard Cnemidophorus littoralis (Squamata, Teiidae) in the restinga de Jurubatiba, Macaé, RJ.

We investigated the diet and foraging of the endemic teiid lizard Cnemidophorus littoralis in a restinga habitat in Jurubatiba, Macaé - RJ. The stomach contents were removed, analyzed and identified to the Order level. There was no relationship between C. littoralis morphological variables and number, length or volume of preys. Termites (48.7%) and larvae (35.5%) were the most important prey items which occurred in the examined lizards' stomachs. The diet did not differ between males and females. Cnemidophorus littoralis is an active forager and predominantly consumes relatively sedentary prey or prey that is aggregated in the environment. We also found an intact and undigested hatchling of the crepuscular/nocturnal gekkonid lizard Hemidactylus mabouia in the stomach of an adult male of C. littoralis, which indicates that C. littoralis is a potential source of mortality for individuals of H. mabouia in the restinga de Jurubatiba.

Animals↗
PubMed2001

Teratoma in desert grassland whiptail lizards (Cnemidophorus uniparens).

The clinical, gross necropsy, and histopathology findings in two unrelated desert grassland whiptail lizards (Cnemidophorus uniparens) with teratoma are described. The desert grassland whiptail is a parthenogenic lizard species with a polyploid chromosomal complement. The chromosome composition of the teratomas from these lizards was not determined.

Animals↗
PubMed2002

Paramyxovirus and reovirus infections in wild-caught Mexican lizards (Xenosaurus and Abronia spp.).

Virus isolation attempts were carried out on wild-caught Xenosaurus grandis, X. platyceps, and Abronia graminea from Mexico. These animals were also tested for exposure to paramyxoviruses and reoviruses. Pharyngeal and cloacal swabs were collected from 30 lizards, and blood was collected from 23 lizards. A cytopathogenic virus was isolated from the cloacal swab of one of the X. platyceps. The isolate was identified as a paramyxovirus on the basis of its sensitivity to chloroform, resistance to 5-iodo-2'-deoxyuridine, size and morphology of the viral particles, hemagglutination of chicken erythrocytes, and serologic reaction with paramyxovirus-specific antisera. Antibodies against the paramyxovirus isolated in this study were found in four animals from three species. Antibodies against a different paramyxovirus isolated from a monitor lizard were found in seven animals from three species, showing that all the species tested are susceptible to paramyxovirus infections. Antibodies to a reptilian reovirus were found in three of the X. grandis.

Animals↗
PubMed2006

Influence of drying time on nematode eggs in scats of scincid lizard Egernia stokesii.

Two pharyngodonid nematode species, Pharyngodon tiliquae and Thelandros trachysauri, infect the Australian lizard Egernia stokesii (gidgee skink) in populations from South Australia. Eggs are detected in lizard scats that are deposited in piles outside the rock crevice refuges that the lizards occupy. Eggs were isolated by salt flotation from fresh scats and from scats that had been dried in simulated field conditions for 7, 14, 21, and 28 days. Egg counts decreased with drying time for both nematode species, but T. trachysauri eggs were still detected after 28 days of drying, whereas P. tiliquae eggs were rarely detected after 14 days. These results suggest that egg counts can be used to infer host infection status only from relatively fresh scats and that eggs of the 2 species persist in a state where they can be detected by standard flotation techniques, for different times.

Analysis of Variance↗
PubMed2006

Refractoriness of the western fence lizard (Sceloporus occidentalis) to the Lyme disease group spirochete Borrelia bissettii.

The western fence lizard, Sceloporus occidentalis, is refractory to experimental infection with Borrelia burgdorferi sensu stricto, one of several Lyme disease spirochetes pathogenic for humans. Another member of the Lyme disease spirochete complex, Borrelia bissettii, is distributed widely throughout North America and a similar, if not identical, spirochete has been implicated as a human pathogen in southern Europe. To determine the susceptibility of S. occidentalis to B. bissettii, 6 naïve lizards were exposed to the feeding activities of Ixodes pacificus nymphs experimentally infected with this spirochete. None of the lizards developed spirochetemias detectable by polymerase chain reaction for up to 8 wk post-tick feeding, infected nymphs apparently lost their B. bissettii infections within 1-2 wk after engorgement, and xenodiagnostic L. pacificus larvae that co-fed alongside infected nymphs did not acquire and maintain spirochetes. In contrast, 3 of 4 naïve deer mice (Peromyscus maniculatus) exposed similarly to feeding by 1 or more B. bissettii-infected nymphs developed patent infections within 4 wk. These and previous findings suggest that the complement system of S. occidentalis typically destroys B. burgdorferi sensu lato spirochetes present in tissues of attached and feeding I. pacificus nymphs, thereby potentially reducing the probability of transmission of these bacteria to humans or other animals by the resultant adult ticks.

Animals↗
PubMed1994

Opioid peptides and testicular activity in the lizard Podarcis s. sicula Raf.

In mammals endorphinergic systems have been shown to modulate reproductive processes and beta-endorphin (beta-EP) has been found to influence sexual functions, acting at the hypothalamus-pituitary-gonadal axis level. Using immunocytochemical and in vitro studies, evidence for a diffuse pro-opiomelanocortin-related opioid system in the lizard Podarcis s. sicula was produced. In the testis, beta-EP immunoreactivity showed seasonal variation, being most pronounced in the interstitial cells of sexually quiescent lizards (December). Reverse-phase high-performance liquid chromatography, coupled with radioimmunoassay and immunocytochemistry, showed that beta-EP and acetyl beta-EP increased during December, while their concentrations were low during April, when the highest testicular activity occurred. Using in vivo studies, it was found that naltrexone treatment, blocking pituitary opioid receptor, increased androgen levels in the plasma and in the testis. It was also found with in vitro studies that the endogenous opioid system inhibits gonadotrophin release and therefore androgen production by the testis. The data reported here provide evidence for the physiological role played by opioid peptides at the pituitary level to regulate the seasonal reproductive activity of the lizard Podarcis s. sicula.

Androgens↗
PubMed2006

Neural interaction of gonadotropin-regulating hormone immunoreactive neurons and the suprachiasmatic nucleus with the paraventricular organ in the Japanese grass lizard (Takydromus tachydromoides).

Our previous study demonstrated that the paraventricular organ (PVO) in the hypothalamus of the Japanese grass lizard (Takydromus tachydromoides) showed immunoreactivity against the light signal-transducing G-protein, transducin. This finding suggested that the PVO was a candidate for the deep-brain photoreceptor in this species. To understand functions of the PVO, we investigated distributions of transducin, serotonin, gonadotropin-releasing hormone (GnRH), and gonadotropin-inhibitory hormone (GnIH) in the lizard's brain. We immunohistochemically confirmed co-localization of transducin and serotonin in PVO neurons that showed structural characteristics of cerebrospinal fluid (CSF)-contacting neurons. GnRH-immunoreactive (ir) cells were localized in the posterior commissure and lateral hypothalamic area. Some of the serotonin-ir fibers extending from the PVO to the lateral hypothalamic area contacted the GnRH-ir cell bodies. GnIH-ir cells were localized in the nucleus accumbens, paraventricular nucleus, and upper medulla, and GnIH-ir fibers from the paraventricular nucleus contacted the lateral processes of serotonin-ir neurons in the PVO. In addition, we found that serotonin-ir fibers from the PVO extended to the suprachiasmatic nucleus (SCN), and the retrograde transport method confirmed the PVO projections to the SCN. These findings suggest that the PVO, by means of innervation mediated by serotonin, plays an important role in the regulation of pituitary function and the biological clock in the Japanese grass lizard.

Animals↗
PubMed1991

Glands distributed in the lamina propria mucosae of the esophagus in the gecko and Japanese lizard.

In an earlier study, we found compound tubular glands distributed in the lamina propria mucosae of human and fowl esophagus. Subsequently, we discovered bottle-shaped glands in the Japanese lizard and gecko esophagus in the same lamina as that of the human and fowl. Moreover those glands produced equivalent pepsinogen granules. We provide below, a detailed description on the results. 1. Bottle-shaped glands were distributed in the lamina propria mucosae of the Japanese lizard and gecko esophagus. 2. A large number of those glands were distributed in the lower region of the esophagus, but did not exist in the upper and middle regions of the esophagus. 3. The esophageal mucous membrane of the gecko and Japanese lizard were covered with a simple columnar ciliated epithelium, and the same epithelium reacted strongly to PAS and AB (pH 2.5), moderately to AB (pH 0.5) or negatively. 4. PAS-AB (pH 2.5) stain presented a dark blue color or a deep red color or a deep red and dark blue mixed color in one section. 5. The above-mentioned glands contained pepsinogen granules. 6. Those glands do not possess parietal cells.

Animals↗
PubMed1992

Histological and histochemical investigations on Japanese lizard esophagus.

The authors previously investigated the bottle-shaped glands distributed in the lamina propria mucosae of the Japanese lizard and gecko. We made two sets of sections of the Japanese lizard at that time. The numerical values of the physical dimensions of the two individuals were as given table 1, showing that No. 2 was slightly smaller. Moreover we found very unusual tissue in the lower portion of the esophagus of No. 2. Therefore we excluded this individual from the preceding investigations. However, we made various observations, and the results of these investigations are as follows. 1. The lumen of the upper portion of the esophagus has no fold. However, the middle and lower portions formed very complicated folds. Therefore, the lumen was remarkably narrow. 2. The epithelium of the esophageal mucous membrane consisted of simple columnar cells and throughout each part, reacted strongly to PAS and moderately to AB (pH 2.5 and 0.5). It presented a dark blue (R18-B13 of Blue-Purple-Red) color in response to PAS-AB (pH 2.5) and contained no pepsinogen granules. The esophageal upper portion of small individuals only exhibited the PAS reaction in this investigation. 3. A number of bottle-shaped glands were distributed in the lamina propria mucosae of the lower portion of the esophagus of each material. The glandular cells in the basal portion were most differentiated and contained a great number of pepsinogen granules. 4. The above-mentioned glands were extremely simple and glands of this type could not be found in textbooks and theses. Accordingly, we previously described them with the tentative name of shimple branched tubular glands, but subsequently found this to be erroneous. We assume that these glands are esophageal gastric glands. 5. Compound tubular glands are formed in the lamina propria mucosae of the human esophagus, but do not exist in the Japanese macaque, crab-eating monkey, horse, cow, swine, dog, cat, rabbit, mouse and rat. Dellmann-Brown also described the absence of such glands in the esophagus of the horse, swine, cow, goat, sheep, dog and cat. 6. We subsequently found compound tubular glands distributed in the lamina propria mucosae of the fowl, goose and wild duck esophagus. They similarly secreted pepsinogen granules. 7. We assume that these glands of the Japanese lizard and gecko have a phylogenic relation with the glands in the bird. The pepsinogen-granule-secreting cells in the snake do not extend into the lamina propria mucosae.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMedDate not supplied

Haematological changes in the garden lizard, Calotes nemoricola due to the defensive secretion of the grasshopper, Poecilocerus pictus.

Defensive secretion of the Grasshopper, Poecilocerus pictus produced significant changes in the blood components of the predator lizard, C. nemoricola. The red blood cell (RBC) count, haemoglobin (Hb) concentration, packed cell volume (PCV), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC) and white blood cell (WBC) count decreased greatly, whereas mean corpuscular volume (MCV) showed significant increase following the administration of lethal dose of defensive secretion. These changes however were found to be reversible toward control levels in the lizards injected with sublethal dose. Disrupted erythropoeitic activity in lizards by the cardenolides in the defensive secretion was suggested.

Analysis of Variance↗
PubMed1975

Experimental infection of anole lizards (Anolis carolinensis) with Mycobacterium ulcerans by the subcutaneous route.

To test whether herpetofauna could be a laboratory model for Mycobacterium ulcerans, 21 anole lizards were inoculated subcutaneously with viable M. ulcerans, 21 with autoclaved organisms, and 14 with an aqueous solution of 0.01% Tween 80. M. ulcerans was recovered in culture from the slowly progressive lesions which developed at the inoculation site in lizards receiving the viable bacteria. Progressive lesions did not occur in the two control groups. Three patterns of inflammatory response to viable M. ulcerans were observed: 14 lizards developed a diffuse, granulomatous reaction in which acid fast bacilli (AFB) were predominantly intracellular; 1 developed focal, encapsulated granulomas; 5 developed a diffuse, necrotizing granulomatous response in which most AFB were extracellular--similar to the characteristic lesion found in human infections.

Animals↗
PubMed1991

Helminth parasites of unisexual and bisexual whiptail lizards (Teiidae) in North America. V. Mesocestoides sp. tetrathyridia (Cestoidea: Cyclophyllidea) from four species of Cnemidophorus.

Two hundred and one whiptail lizards, Cnemidophorus spp., from Texas and Colorado (USA), were examined for Mesocestoides sp. tetrathyridia. Eleven (5%) were infected, including three of 58 (5%) C. dixoni, six of 70 (9%) C. gularis septemvittatus, one of 35 (3%) C. marmoratus, and one of 34 (3%) C. tesselatus; four C. inornatus heptagrammus were not infected. In addition, 41 non-cnemidophorine lizards from the same study area were not infected. Free tetrathyridia were found in the body cavity of lizards and encapsulated tetrathyridia were observed in the heart, liver, stomach, mesenteries, ovaries, intestines, and lungs. None of the Mesocestoides sp. exhibited any evidence of asexual proliferation such as multiple scoleces or buds. This note, the fifth in a series of reports on helminths of Cnemidophorus spp., represents the first time Mesocestoides sp. has been reported from these four taxa, and Colorado is a new geographic locality record for this parasite.

Animals↗
PubMed1992

Ectoparasite-induced lesions in mite pockets of the Yarrow's spiny lizard, Sceloporus jarrovii (Phrynosomatidae).

Histopathological effects of the chigger, Eutrombicula lipovskyana, on the mite pockets of neonatal, juvenile and adult Yarrow's spiny lizard, Sceloporus jarrovii, were investigated. Focal ulcerative dermatitis was noted in all age classes. This reaction was more diffuse in older animals in which penetration as deep as the panniculus occurred. Based on the occurrence of inflammatory reactions in neonatal lizards, S. jarrovii appears capable of recognizing foreign antigens shortly after birth. There was an increased inflammatory response in older lizards that may have been an augmented host sensitivity following repeated exposure to chiggers. Granulomas, which were interpreted as an attempt to isolate the effects of chigger bites, were noted in juveniles and adults. We propose that S. jarrovii does not develop resistance after repeated exposures to E. lipovskyana.

Animals↗
PubMed1999

Hormonal regulation of progesterone receptor mRNA expression in the hypothalamus of whiptail lizards: regional and species differences.

The effects of gonadal steroid hormones on steroid receptor mRNA expression vary across nuclei within the brain, between the sexes, and between species. We report that exogenous estrogen increases progesterone receptor (PR) mRNA levels in the periventricular preoptic area in an ancestor and descendant species pair of whiptail lizards, and also that this effect of estrogen is significantly stronger in females of the descendant species. Second, while progesterone strongly decreases PR mRNA in the ventromedial hypothalamus of whiptail lizards and rodents, we find that there is no discernible effect of progesterone on PR mRNA levels in the periventricular preoptic area in females of the ancestral member of this species pair. These findings are a further demonstration of the variability of steroid effects on steroid receptor mRNA levels across brain nuclei. This variability may be important both in behavioral transitions over the course of the ovarian cycle in this ancestor-descendant species pair of lizards and in the evolution of pseudosexual behavior in the descendant parthenogen species.

Animals↗
PubMed1999

Lymphosarcoma with leukemic blood profile in a Savannah monitor lizard (Varanus exanthematicus).

A 6-mo-old male Savannah monitor lizard (Varanus exanthematicus) was presented for lethargy and anorexia of 7 days duration. Physical examination revealed a slightly raised subcutaneous mass (1 cm diameter) in the left scapular area. Fine-needle aspiration cytology of the mass revealed a population of immature, pleomorphic lymphoid cells consistent with lymphosarcoma. A hemogram indicated marked leukocytosis (465,000 cells/microl) characterized by extreme lymphocytosis and many circulating lymphoid blast cells. The lizard was euthanized at the owner's request. Necropsy revealed severe hepatomegaly and multiple raised, ulcerated mural masses in the gastrointestinal tract. There were many raised, poorly demarcated tan foci in all the parenchymal organs. Histopathologic examination confirmed infiltration of all parenchymal organs by neoplastic lymphoid cells. Transmission electron microscopic examination failed to identify viruses within the neoplastic cells. A literature review revealed few reports of squamate leukemia and lymphosarcoma and none in Savannah monitor lizards.

Animals↗
PubMed1999

Effect of cholinergic agonists on muscular tonus of the lizard small intestine and esophagus.

The underlying mechanisms of acetylcholine-induced intestinal relaxation in the lizard Liolaemus tenuis tenuis are still unknown. By using a classical model of intestinal recording of isometric contraction and relaxation in conjunction with specific pharmacological tools, this article studies the possible influence of EDRF/NO and nicotinic ganglionar receptors on the Ach-induced relaxation in an effort to elucidate the probable mechanisms involved in ACh effect. It was observed that the relaxation of the lizard intestine elicited by ACh (10(-7) - 4 x 10(-4) M) was not affected by hexametonium (5 x 10(-4) M) or tetrodotoxin (10(-6) M). Nicotine (10(-7) to 10(-4) M) induced relaxation was significantly antagonized by hexametonium; however, it was not influenced by tetrodotoxin. These results allow us to discard a neuronal pathway in cholinergic-induced relaxation, suggesting a more direct cholinergic effect on the smooth muscle, perhaps mediated by an unknown substance released by some specialized tissue. N-nitro-L-arginine, used to block NO-synthase and NO production, induced no changes in ACh-induced relaxation. Methylene blue, a soluble guanylate cyclase inhibitor, induced no changes in ACh-induced relaxation. These results allow us to discard a probable role of EDRF/nitric oxide in the ACh-induced relaxation of lizard small intestine, providing evidence that this mechanism could be different from that reported in other species.

Animals↗
PubMed2002

Dose-response and time course relationships for vitellogenin induction in male western fence lizards (Sceloporus occidentalis) exposed to ethinylestradiol.

The long-term goal of this research is to develop and validate an in vivo reptile model for endocrine-mediated toxicity using fence lizards (Sceloporus spp.). One of the best defined estrogenic responses in oviparous vertebrates is induction of the yolk precursor protein, vitellogenin (Vtg). In this study, dose-response and time course relationships for Vtg induction were determined in male western fence lizards (Sceloporus occidentalis) given intraperitoneal injections of 17alpha-ethinylestradiol (EE2). Plasma Vtg was quantified directly with an antibody-capture enzyme-linked immunosorbent assay (ELISA) and indirectly using plasma alkaline-labile phosphate (ALP) in order to compare these two methods. Both ELISA and ALP predicted similar median effective dose (ED50 [dose causing a 50% maximal response]) values for plasma Vtg induction (0.167 mg/kg for ELISA and 0.095 mg/kg for ALP). In addition, both ELISA and ALP detected significant Vtg induction at a dose of 0.0003 mg/kg of EE2, which was the lowest dose used in our study. A decrease in body weight at the highest dose (10 mg/kg) and an increase in hepatosomatic index at the four highest doses were observed. Serial dilutions of plasma from an EE2-exposed male revealed a high correlation between plasma Vtg and ALP determinations in this species. In conclusion, our data show that plasma ALP may be a suitable alternative for measuring plasma Vtg compared with developing a Vtg ELISA in fence lizards exposed to estrogenic compounds.

Animals↗
PubMed2002

Lizard cholinesterases as biomarkers of pesticide exposure: enzymological characterization.

Here we report the results of a study conducted to elucidate the enzymological characteristics of lizard cholinesterases (ChEs) in order to use them as potential biomarkers for pesticide exposure. Serum and brain tissue of the lizard Gallotia galloti were used as ChE sources and in vitro assays were performed to identify acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activities. The pH, substrate concentration, and specificity for ChE assays as well as the response of serum BChE to the reactivating agent pyridine-2-aldoxime methochloride (2-PAM) were also investigated in order to assess the possibilities of this methodology in biomonitoring programs. By the use of selective substrates and the inhibitor tetraisopropyl pyrophosphoramide, AChE and BChE activities were identified in lizard serum, while brain contained solely AChE. Likewise, butyrylthiocholine iodide was the optimum substrate for determining BChE activity and acetylthiocholine iodide for assaying both serum and brain AChE activities. The optimal ranges of pH and substrate concentrations were 7.5 to 8.0 and 5 to 10 mM, respectively. Serum was incubated with different doses of the organophosphorus (OP) compounds dichlorvos and paraoxon and subsequently incubated in the presence of two concentrations of 2-PAM (2 x 10(-2) or 2 x 10(-4) M). Reactivation rate of phosphorylated BChE was related to the degree of inhibition of BChE and the dose of 2-PAM. It was found that a 90-min incubation time with 2 x 10(-4) M of 2-PAM satisfactorily increased the OP-inhibited BChE activity. The enzymological properties of serum BChE activity and its in vitro reactivation in the presence of 2-PAM represent the initial justification for its use in monitoring OP contamination in the field.

Acetylcholinesterase↗