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PubMed1988

Primary in vitro stimulation of antibody production by lizard splenocytes.

Single-cell suspensions of adult lizard (Chalcides ocellatus) spleen have been induced, in vitro, to produce a primary immune response. Using rat red cells (RRBC) as antigen and the culture conditions normally used in most vertebrate species but new for reptilia, it has been found that, in vitro at 37 degrees C, lizard spleen cells produce an antibody-forming response optimal at day 10. The response depends on the number of cultured cells and the dose of antigen, and parallels that obtained in vivo. Leibovitz (L-15) medium supplemented with 10% normal adult lizard serum was a satisfactory culture medium. 2-mercaptoethanol (2-ME), an ingredient used in mammalian cell culture, enhanced antibody production in lizard cells.

Animals↗
PubMed1988

Comparison of several lizard Leishmania species and strains in terms of kinetoplast minicircle and maxicircle DNA sequences, nuclear chromosomes, and membrane lipids.

Eight strains of a lizard Leishmania species, L. tarentolae, were compared with four other saurian species [L. hoogstrali, L. adleri, L. agamae and Leishmania sp. LizS], with L. major from man and with Trypanosoma platydactyli, a putative lizard trypanosome, in terms of kinetoplast DNA minicircle and maxicircle sequences and in terms of nuclear chromosome patterns on orthogonal gel electrophoresis. The L. tarentolae strains fell into two major groups, one (group A) consisting of the L. tarentolae strains, UC, Krassner and Trager, derived from an Algerian gecko isolate and the other (group B) consisting of five L. tarentolae LEM strains isolated from geckos in southern France. T. platydactyli TPCL2, which was postulated by Wallbanks et al. to represent the lizard form of a French L. tarentolae strain, was closely related to the UC strain and not to the LEM strains, in all respects analyzed. Leishmania sp. LizS from a Mongolian gecko and L. hoogstrali from a Sudanese gecko showed some sequence similarities to the L. tarentolae strains, but the leishmanias said to be L. adleri from a Kenyan lacertid and L. agamae from an Israeli agamid showed no minicircle sequence similarities with lizard Leishmania and in fact were probably the same species. The maxicircle divergent region was larger in the group B strains than in the group A strains, but there were sequences in common with both groups, and not with L. hoogstrali and L. major. Four strains of L. tarentolae, the four other supposed saurian Leishmania species, three mammalian leishmanias, T. platydactyli and four other trypanosomes, T. cyclops (Malaysian macaque), T. conorrhini (Hawaiian reduviid bug), T. cruzi (man) and T. lewisi (feral rat) were analyzed for their contents of sterols and phosphoglyceride fatty acyl groups. T. platydactyli TPCL2 contained a sterol (5-dehydroepisterol), a phosphatidylcholine fatty acyl group (alpha-linolenic acid) and a phosphatidylethanolamine fatty acyl group (dihydrosterculic acid) characteristic of members of the genus Leishmania and not the genus Trypanosoma. The proportions of those lipids in the free sterol and phosphoglyceride fractions of T. platydactyli TPCL2 most closely resembled those seen in the Leishmania strains from Algerian, French, Mongolian and Sudanese geckos.

Animals↗
PubMed1982

Some biochemical changes in the ageing heart of the male garden lizard.

The SDH activity of cardiac muscle homogenates reached a peak level in the middle-aged lizards followed by a decline in the old. The inhibition of enzyme activity by oxaloacetate, a competitive inhibitor, declined with advancing age. Both salt and acid solubilities of cardiac muscle collagen declined with advancing age of the lizard. An age-related accumulation of total collagen was evident per organ basis but a reverse trend prevailed on the basis of relative value. Quantitative estimations revealed a loss of DNA in ageing heart; per organ basis the DNA content increased till the lizards were middle-aged showing no further change thereafter. On the other hand the RNA content and the RNA/DNA ratio of cardiac muscle declined between young and middle-aged followed by a rise in the old lizards. The protein content increased with rise in fresh weight of heart during ageing.

Aging↗
PubMed1981

Effects of MIF-I and sex differences on tonic immobility duration in the lizard, Anolis carolinensis.

In June, 36 lizards (males and females) were injected with 0.01, 0.1, 1.0, 10.0, or 100 mg/kg of MIF-I, or the diluent vehicle, and placed in a cage for ten minutes. Tonic immobility (TI) was then induced on an open lab table. All doses of MIF-I significantly reduced TI duration as compared to the duration with the diluent alone. In subsequent experiments lizards were injected with 0.1 mg/kg of MIF-I, 0.1 mg/kg of naloxone, or the diluent vehicle, and placed in small aquaria for ten minutes. TI was then induced in the small aquaria. In July, using 60 females, MIF-I and naloxone slightly reduced the duration of TI, but not significantly, and overall TI durations were reduced as compared with the first experiment possibly because the lizards could escape from the view of the experimenter in the corners of the aquaria. A third experiment was done in late September and early October with 120 males and 120 females. No drug effect was seen, but there was a significant difference between the TI durations of males and females, the females having longer durations. A relationship between the difference in response to MIF-I and the breeding seasons of the lizards could not be determined due to the possibility that the change in experimental design after the June experiments may alone have accounted for the loss of the significant response to MIF-I.

Animals↗
PubMed1988

Thyroid function in a lizard, a tortoise and a crocodile, compared with mammals.

1. Thyroid activity was examined in the lizard, Trachydosaurus rugosus, the tortoise Chelodina longicollis and the crocodile, Crocodylus johnstoni, acclimated to 20-22 degrees C and 30-32 degrees C. Thyroidal uptake and release of 125I, plasma concentrations of T3 and T4 were measured as was resting oxygen consumption (at 30 degrees C) before and after both thyroidectomy and thyroxine injections. 2. All three species showed 125I uptake at both temperatures and showed no thyroidal release of 125I at 20-22 degrees C but exhibited thyroidal release of 125I (and presumably hormone secretion) at 30-32 degrees C. 3. Plasma concentrations of thyroxine ranged from 0.55 nM to 3.24 nM and triiodothyronine from 0.14 nM to 0.51 nM. 4. Neither thyroidectomy nor thyroxine injections had any effect on metabolic rate in 20-22 degrees C acclimated lizards. Thyroidectomy resulted in a significant decrease in metabolic rate in 30-32 degrees C acclimated lizards and tortoises and thyroxine injections resulted in significant increases in metabolism in 30-32 degrees C acclimated lizards, tortoises and crocodiles. 5. A comparison of thyroid parameters in reptiles and mammals concluded that although the reptilian thyroid is active at high temperatures it is still considerably less active than it is in mammals.

Alligators and Crocodiles↗
PubMed1984

Responses of European green lizards Lacerta viridis following administration of Leishmania agamae promastigotes.

European green lizards (Lacerta viridis) were injected intraperitoneally, subcutaneously or orally with viable Leishmania agamae promastigotes. Neither promastigotes nor amastigotes were later found in blood and tissue impression smears, or in blood and selected organ cultures. However, by the use of an immunoperoxidase technique, parasite antigens were detected in the liver, stomach, small intestine, kidney, gonad, heart, lung and skin but not in the bone marrow, brain or spleen. Non-precipitating antibodies with beta 2-electrophoretic mobility were induced against L. agamae. They were detected in the sera by enzyme-linked immunosorbent assay 3-7 days post-infection. The titres increased significantly above background levels (P less than 0.001) and reached maxima after 6-7 weeks, with 27 out of 29 lizards producing antibodies. The mean serum protein concentration significantly increased after infection (P less than 0.005) with no significant differences in mean values between male and female animals. Lizard sera separated into 7 components on cellulose acetate membranes with migration rates comparable to albumin, alpha- and beta-globulins of human serum; gamma-globulins were absent. Significant decreases occurred (P less than 0.05) in the albumin fraction, with significant increases in the beta-globulin region of anti-L. agamae sera. C-reactive protein was not detected in either normal or immune lizard sera.

Animals↗
PubMed1992

Narine occlusion decreases basal levels of Fos protein in the cerebral cortex of the lizard Podarcis hispanica.

Immunocytochemical study of cerebral cortex of the lizard Podarcis hispanica using an antibody directed to the M peptide of the rat c-Fos protein showed a distinct pattern of Fos distribution. Abundant Fos-immunoreactive neuronal nuclei were detected in the cell layers of the medial, the dorsal and the lateral cortices, whereas only a few nuclei were found in the cell layer of the dorsomedial cortex. The Fos immunoreactivity was characterized by Western blot analysis of nuclear extracts from lizard brain and showed a distinct band with an apparent molecular weight of 30,000. In band-shift assays, nuclear extracts from lizard brain were shown to contain AP-1 complexes. The basal expression of Fos immunoreactivity is related to sensory olfactory input in the cerebral cortex of the lizard since experiments with olfactory-deprived animals resulted in a complete absence of Fos immunoreactivity in the cortical areas.

Animals↗
PubMed2004

Hysteresis of heart rate and heat exchange of fasting and postprandial savannah monitor lizards (Varanus exanthematicus).

Reptiles are ectothermic, but regulate body temperatures (T(b)) by behavioural and physiological means. Body temperature has profound effects on virtually all physiological functions. It is well known that heating occurs faster than cooling, which seems to correlate with changes in cutaneous perfusion. Increased cutaneous perfusion, and hence elevated cardiac output, during heating is reflected in an increased heart rate (f(H)), and f(H), at a given T(b), is normally higher during heating compared to cooling ('hysteresis of heart rate'). Digestion is associated with an increased metabolic rate. This is associated with an elevated f(H) and many species of reptiles also exhibited a behavioural selection of higher T(b) during digestion. Here, we examine whether digestion affects the rate of heating and cooling as well as the hysteresis of heart rate in savannah monitor lizards (Varanus exanthematicus). Fasting lizards were studied after 5 days of food deprivation while digesting lizards were studied approximately 24 h after ingesting dead mice that equalled 10% of their body mass. Heart rate was measured while T(b) increased from 28 to 38 degrees C under a heat lamp and while T(b) decreased during a subsequent cooling phase. The lizards exhibited hysteresis of heart rate, and heating occurred faster than cooling. Feeding led to an increased f(H) (approximately 20 min(-1) irrespective of T(b)), but did not affect the rate of temperature change during heating or cooling. Therefore, it is likely that the increased blood flows during digestion are distributed exclusively to visceral organs and that the thermal conductance remains unaffected by the elevated metabolic rate during digestion.

Animals↗
PubMed2004

Nursing care of lizards.

This article should introduce to the veterinary staff some of the basic information that is required to provide high-quality medicine to lizards. This article begins with a brief introduction to lizards and their husbandry, including caging, lighting, humidity, and diet.Making appointments for lizards, taking a history, manual restraint,venipuncture, fecal sampling, catheterization, medications,administering fluids, giving injections, radiology, and anesthesia are all detailed for veterinary technicians and veterinary animal care staff. Each section details differences between lizards and typical mammalian patients while trying to emphasize the common approach to both groups of animals.

Animal Husbandry↗
PubMed2005

Molecular cloning and characterization of the clock gene period2 in the testis of lizard Podarcis sicula and its expression during seasonal reproductive cycle.

Clock genes are known to oscillate with circadian rhythmicity in the central clock structure, the suprachiasmatic nucleus of the hypothalamus, and also in peripheral tissues. Reproduction is a peripheral activity that is strongly influenced by a circadian clock in many organisms. Most mammals that exhibit a seasonal cycle are able to decode the daily changes in light across the year and to translate these in hormonal signals that regulate reproductive cycles. Expression of many clock genes has been revealed in mouse testis, although transcription of these genes seems to be constitutive in 24 h, suggesting that these genes may play in the testis a different role with regard to the central clockwork function. The seasonal breeding lizard Podarcis sicula represents an attractive model for studying some developmental and differentiation phenomena, such as gonadal maturation, since in the adult male the testis shows a spring full activity and a complete summer regression. Experimental data seem to suggest that in lizard the environmental factors, as photoperiod and temperature, affect the endogenous elements, although the interaction mechanisms are unknown. It is known that temperature signals have a direct influence on clock processes such as transcription, translation, protein phosphorylation and degradation. In addition, most data show that the expression of circadian clock genes, such as period2, is affected by length of photoperiod. In this way, the core clockwork may also decode seasonal information. Here we report the cloning, sequencing and bioinformatic analysis of period2 gene, isolated from the testis of lizard P. sicula, and its expression both in the testis and in other tissues during the different phases of the seasonal cycle. RT-PCR assays enlighten the presence of transcript in testis, brain, heart, liver and kidney in all the phases analysed. Moreover, real time quantitative PCR assays detect a peak of per2 testicular expression during gonadal regression. Our preliminary results cannot clearly demonstrate the involvement of per2 gene in seasonal reproductive cycle of male lizard P. sicula, but its presence in the testis may suggest a role of this gene during spermatogenesis. Besides, our work can provide numerous starting points to clarify the role of per2 during seasonal reproductive cycle.

Amino Acid Sequence↗
PubMed2006

Mitochondrial genomes from major lizard families suggest their phylogenetic relationships and ancient radiations.

In placental mammals and birds, molecular data generally support a view that they diverged into their ordinal groups in good response to mid-Cretaceous continental fragmentations. However, such divergence patterns have rarely been studied for reptiles for which phylogenetic relationships among their major groups have not yet been established molecularly. Here, I determined complete or nearly complete mitochondrial DNA sequences from seven lizard families and reconstructed phylogenetic relationships between major lizard families. When snakes were included, maximum likelihood analysis did not support a morphological view of the snakes-varanoids affinity, although several other competing hypotheses on the position of snakes still cannot be discriminated presumably due to extremely long branches of the snake lineages. I also conducted clock-free Bayesian analyses to show that divergence times between major lizard families were centered in Triassic-Jurassic times. Thus, lizards include much deeper divergences than the mammals and birds and they appear to have already radiated into various families prior to the mid-Cretaceous major continental fragmentation.

Animals↗
PubMed2005

Molecular identification of lizard by RAPD & FINS of mitochondrial 16s rRNA gene.

In the present study, we identified the structure-less skeleton suspected to be of house lizard present in jaggery, consumption of which caused mass food poisoning using, RAPD (Random Amplification of Polymorphic DNA) with random primers and FINS (Forensically Informative Nucleotide Sequencing) with mitochondrial 16s rRNA gene. The NJ tree dendogram based on distance calculated from RAPD bands clearly identified the structure-less as Calotes versicolor (Garden Lizard). In FINS analysis of the mitochondrial 16s rRNA gene the NJ tree based on Kimura-2-parameter distance matrices clearly reveal that the unknown sample clustered with Agmidae family and closest to Calotes versicolor (Garden Lizard) with 100% bootstrap support, whereas all other species belong to Gekkonida family form a single distinct cluster including Hemidactylus fluviviridis (House Lizard). This is the first successful typing of mitochondrial 16s rRNA with FINS approach to identify the biological origin of a structure-less skeleton. Our analysis also sustained successful identification of unknown samples using RAPD method with optimized conditions in a laboratory setup with low resources.

Animals↗
PubMed2004

Seasonal changes in blood oxygen transport and acid-base status in the tegu lizard, Tupinambis merianae.

Oxygen-binding properties, blood gases, and acid-base parameters were studied in tegu lizards, Tupinambis merianae, at different seasons and temperatures. Independent of temperature and pH, blood oxygen affinity was higher in dormant lizards than in those active during the summer. Haematocrit (Hct) and hemoglobin content ([Hb]) were greater in active lizards resulting in a higher oxygen-carrying capacity. Nucleoside triphosphate content ([NTP]) was reduced during dormancy, but the ratio between [NTP] and [Hb] remained unchanged. Dormancy was accompanied by an increase in plasma bicarbonate ([HCO-(3)]pl) and an elevation of arterial CO2 partial pressure (PaCO2) and CO2 content in the plasma (CplCO2). These changes in acid-base parameters persist over a broad range of body temperatures. In vivo, arterial O2 partial pressure (PaO2) and O2 content (CaO2) were not affected by season and tended to increase with temperature. Arterial pH (pHa) of dormant animals is reduced compared to active lizards at body temperatures below 15 degrees C, while no significant difference was noticed at higher temperatures.

Acid-Base Equilibrium↗
PubMed2005

Morphology, cytochemical staining, and ultrastructural characteristics of the blood cells of the giant lizard of El Hierro (Gallotia simonyi).

The object of this study was to examine the erythrocytes, leukocytes and thrombocytes of the giant lizard of El Hierro (Gallotia simonyi) by light and electron (TEM) microscopy, and cytochemical staining. Smears were prepared from blood from the ventral coccygeal vein of 10 healthy adult lizards (five males and five females) from the Giant Lizard of El Hierro Reproduction and Research Centre, Canary Islands, Spain. The cytochemical stains used were: benzidine peroxidase (BP), chloroacetate esterase (CAE), alpha-naphthyl acetate esterase (ANAE), acid phosphatase (AP), periodic acid-Schiff (PAS), toluidine blue (TB) and May-Grünwald-Giemsa (MGG). Electron microscopy was also performed on all samples. Heterophils had granules that were heterogeneous in both size and electron density, and stained with BP, PAS and ANAE. Eosinophil granules were homogeneously electron-dense and stained for AP, CAE and ANAE. Basophils had both highly and moderately electron-dense granules, and stained with TB and ANAE. Azurophil granules were of low electron-density and stained for AP, CAE and ANAE. Azurophil cytoplasm was vacuolated on TEM. The cytoplasm of lymphocytes contained many ribosomes and was positive for AP. Monocytes had a large nucleus and a vacuolated cytoplasm but did not stain by any of the cytochemical methods used. Thrombocytes had a relatively large nucleus but little cytoplasm; they did not stain cytochemically. The blood cells of the giant lizards of El Hierro differ from those of other members of the Order Squamata both morphologically and cytochemically. The variation in cytochemical responses in the blood of reptiles makes it necessary to study species individually if meaningful clinical decisions are to be made.

Animals↗
PubMed2000

Plastic changes and nitric oxide synthase induction in neurons which innervate the regenerated tail of the lizard Gekko gecko. II. The response of dorsal root ganglion cells to tail amputation and regeneration.

The lizard tail regenerates after amputation, which severs the spinal cord and spinal nerves. Dorsal root ganglia (DRGs) do not regenerate in the regrowing tail, which is innervated by DRGs rostral to the amputation. With Nissl staining, NADPH-diaphorase histochemistry and nitric oxide synthase (NOS) immunohistochemistry, we investigated NOS expression and its relationship with structural changes in DRG neurons of caudotomized lizards. First, by horseradish peroxidase retrograde tracing we here provided evidence that the sensory innervation of the regenerated tail derives only from the three pairs of DRGs rostral to the amputation plane. These ganglia were then analyzed in control animals with original intact tail, at 5, 15 and 30 days after caudotomy, and at 8 months in lizards with mature regenerates. Caudotomy elicited in DRG neurons marked hypertrophy that persisted after tail regeneration. In control ganglia, most neurons were lightly NADPH-diaphorase-positive, a few were unstained or intensely stained. Tail transection elicited marked staining up-regulation, and an increase in the proportion of intensely positive neurons. The staining intensity peaked in DRG neurons at 15 days and was still significantly increased in respect to controls several months after complete tail regeneration. NOS immunoreactivity in DRGs matched the histochemical findings. NADPH-diaphorase positivity was also enhanced in the dorsal horn superficial laminae of the corresponding spinal segments. We demonstrate that transection of the lizard spinal nerves, provoked by tail loss, elicits in the axotomized primary sensory neurons marked NOS enhancement, which accompanies axon elongation in the regrowing tail and persists after the end of this process.

Amputation, Surgical↗
PubMed2000

Androgen receptor-immunoreactivity in the forebrain of the Eastern Fence lizard (Sceloporus undulatus).

Androgen receptor (AR) distribution in the lizard forebrain and optic tectum was examined using PG21 immunohistochemistry. In the male Eastern Fence lizard, AR-immunoreactive (-ir) nuclei were observed in the medial preoptic area, ventromedial and arcuate hypothalamic nuclei, periventricular hypothalamus, premammillary nucleus, bed nucleus of the stria terminalis, and ventral posterior amygdala. Punctate immunostaining of neuronal processes (axons and/or dendrites) was concentrated in the cortex, hypothalamus, and optic tectum. AR-ir nuclei in the female brain were confined to the ventral posterior amygdala and ventromedial hypothalamic nucleus. The AR distribution in the lizard brain is similar to that reported for other vertebrate classes. Sex differences in AR-immunoreactivity may contribute to sex-specific behaviors in the Eastern Fence lizard.

Animals↗
PubMed2002

A possible alternative to 17beta-estradiol in a viviparous lizard, Tiliqua nigrolutea.

We have detected an unusual polar steroid as a major end product of gonadal steroid biosynthesis in male and female blotched blue-tongued lizards, Tiliqua nigrolutea. In an investigation of the steroidogenic pathways in blue-tongued lizards, we incubated gonads of both male and female lizards with tritiated pregnenolone and identified the products of steroid biosynthesis using thin layer chromatography and high performance liquid chromatography with radiometric detection: gonads from both reproductively active and quiescent lizards were examined. The proportion of total radioactive substrate converted to the unknown polar steroid was greater in individuals with hypertrophied gonads (males (N=4) 28.1%; females (N=4) 45.3%) than in those with regressed gonads (males (N=4) 5.9%; females (N=4) 33.3%). Properties of the unknown steroid were identical across all incubations. Incubation time-course information, thin layer and high performance liquid chromatography properties of the polar steroid are presented. The steroid is more polar than 17beta-estradiol, which was not detected, but less polar than all tri-hydroxylated estrogens to which it was compared. The possibility of an alternative estrogen to 17beta-estradiol in some reptiles is discussed.

Animals↗
PubMed2002

Two distinct functional spliced leader RNA gene arrays in Leishmania tarentolae are found in several lizard Leishmania species.

A second distinct array of spliced leader RNA genes has been found in several Leishmania species particular to lizards. This is the first report of two non-allelic arrays of spliced leader RNA genes within a species cell line. The arrays are identical to each other in their transcribed spliced leader RNA gene sequences, but variable in their non-transcribed spacer sequences. In the two arrays from Leishmania tarentolae UC strain the promoter regions are similar, but not identical, at positions shown previously to be critical for spliced leader RNA transcription. These arrays contain similar numbers of genes and are both transcribed in L. tarentolae in vitro transcription extract as well as in vivo. The -66/-58 regions of both genes, which contain an element of the spliced leader RNA gene promoter, bind proteins likely to be transcription factors in a specific manner. A survey of lizard Leishmania spp. revealed a second spliced leader RNA gene array in three of four species. Phylogenetic analyses of these sequences with each other and with the spliced leader RNA gene sequences of non-lizard Leishmania spp. and their near-relatives showed that the lizard groups are more closely related to each other than to arrays from other Leishmania spp. As the transcripts of the two arrays are identical, they may co-exist to fulfil the substantial requirement for spliced leader RNA production; however, they have the potential for differential usage modulated by their distinct promoter elements. The presence of two distinct spliced leader RNA gene arrays within a single cell type may represent dissociated evolution of two redundant loci, or a previously unsuspected level of control in the post-transcriptional gene expression within some kinetoplastids.

Alleles↗