Reproductive biology and feeding habits of Stenocercus caducus (Iguanidae) in semideciduous forest in central Brazil.

Sexual dimorphism, reproduction and diet are described for Stenocercus caducus from semideciduous forest, in Mato Grosso do Sul state, Central Brazil. Lizards are collected in pitfall traps from December 2000, to December 2001. Sexual dimorphism in S. caducus is apparent, mainly in coloration; although females reach a larger SVL than males. A wide variety of arthropods are fed by S. caducus, with ants and termites numerically, and orthopterans and beetles volumetrically the most common prey items. Ontogenetic differences in diet were noted for S. caducus, with juveniles feeding on lesser prey types and smaller sized prey than adults. The reproduction was seasonal, concentrated in the rainy season, with deposition of more than one clutch per season.

Density of the tegu lizard (Tupinambis merianae) and its role as nest predator at Anchieta Island, Brazil

Mammals has been pointed out to be the main nest predators in islands, but recent studies has shown that tree snakes are also important nest predator in tropical forests. Here we present information on the density tegu lizards Tupinambis merianae and its role as nest predator at Anchieta Island, Ubatuba, in southeastern Brazil. The mean density of tegu lizards wets estimated to be 83 individuals/km2, which is 1.83 times lower than other well-known population (Fernando de Noronha Archipelago). In the dense rainforest, the density was estimated in 20 individuas/ km2, and in the open rainforest, 109 ind/km2. The high density of this lizard may have serious implications for nest predation. We found that 36% of artificial plasticine eggs were "preyed upon" by tegu lizards. Therefore, it is paramount to manage the tegu population on Anchieta Island to assure the survival of ground nesting birds in islands and possibly in forest fragments.

Frugivoria e dispersão de sementes pelo lagarto teiú Tupinambis merianae (Reptilia: Teiidae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The role of nitric oxide in regulation of the cardiovascular system in reptiles

The roles that nitric oxide (NO) plays in the cardiovascular system of reptiles are reviewed, with particular emphasis on its effects on central vascular blood flows in the systemic and pulmonary circulations. New data is presented that describes the effects on hemodynamic variables in varanid lizards of exogenously administered NO via the nitric oxide donor sodium nitroprusside (SNP) and, preliminary data on the effects of SNP inhibition of nitric oxide synthase (NOS) by L-nitroarginine methyl ester (L-NAME). Furthermore. on hemodynamic variables in the tegu lizard are presented. The findings are compared with previously published data from Our laboratory on three other species of reptiles: pythons (Skovgaard, N., Galli, G., Taylor, E.W., Conlon, J.M., Wang.. T., 2005. Hemodynamic effects of python neuropeptide gamma in the anesthetized python, Python regius. Regul. Pept. 18, 15-26), rattlesnakes (Galli, G., Skovgaard, N., Abe, A.S., Taylor, E.W., Wang, T., 2005. The role of nitric oxide in the regulation of the systemic and the pulmonary vasculature of the rattlesnake, Crotalus durissus terrificus. J. Comp. Physiol. 175B, 201-208) and turtles (Crossley, D.A., Wang, T., Altimiras, J., 2000. Role of nitric oxide in the systemic and pulmonary circulation of anesthetized turtles (Trachemys scripta). J. Exp. Zool. 286, 683-689). These five species of reptiles possess different combinations of division of the heart and structural complexity of the lungs. Comparison of their responses to NO donors and NOS inhibitors may reveal whether the potential contribution of NO to vascular tone correlates with pulmonary complexity and/or with blood pressure. All existing studies oil reptiles have clearly established a potential role for NO in regulating vascular tone in the systemic circulation and NO may be important for maintaining basal systemic vascular tone in varanid lizards, pythons and turtles, through a continuous release of NO. In contrast., the pulmonary circulation is less responsive to NO donors or NOS inhibitors, and it was only in pythons and varanid lizards that the lungs responded to SNP. Both species have a functionally separated heart, so it is possible that NO may exert a larger role in species with low pulmonary blood pressures, irrespective of lung complexity. (C) 2005 Elsevier B.V. All rights reserved.

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)(-)]PI) and an elevation of arterial CO(2) partial pressure (P(aCO2)) and CO(2) content in the plasma (C(PlCO2)). These changes in acid-base parameters persist over a broad range of body temperatures. In vivo, arterial O(2) partial pressure (Pa(O2)) and O(2) content (Ca(O2)) were not affected by season and tended to increase with temperature. Arterial pH (pH(a)) of dormant animals is reduced compared to active lizards at body temperatures below 15 degreesC, while no significant difference was noticed at higher temperatures. (C) 2003 Elsevier B.V. All rights reserved.

Diet of the colubrid snake, Thamnodynastes strigatus (Günther, 1858) from Paraná State, Brazil, with field notes on anuran predation

São apresentados dados da dieta de Thamnodynastes strigatus (Serpentes: Colubridae), a partir da dissecção de 44 espécimes. No tubo digestivo dos exemplares examinados foram encontrados anfíbios anuros (71,4% da amostra), roedores (14,3%), peixes (10,7%) e lagartos (3,6%). A maioria das espécies de anuros (Bufo sp., Leptodactylus sp., Physalaemus cuvieri e Scinax fuscovarius) encontradas no exame de conteúdo estomacal de T. strigatus, utiliza o solo ou o nível d'água como sítio de vocalização. Também são apresentados dados sobre a observação de eventos de predação na natureza.

Lagartos (Squamata: Lacertilia) em áreas de floresta e de pastagem em Espigão do Oeste, Rondônia, sudoeste da Amazônia, Brasil

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Hábitos alimentares de serpentes em Espigão do Oeste, Rondônia, Brasil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Répteis do Estado de São Paulo: conhecimento atual e perspectivas

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Herpetofauna do Parque Estadual Carlos Botelho, São Paulo, Brasil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Pampean lizard assemblage from subtropical Brazil: a temporal analysis

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Molecular characterization of hemoglobin alpha-D chains from Geochelone carbonaria and Geochelone denticulata land turtles

In order to help elucidate the evolution of alpha-globins, the complete cDNA and amino acid sequences of Geochelone carbonaria and Geochelone denticulata land turtles alpha-D chains have been described. In G. carbonaria, the cDNA is 539 bp with ATG start codon located at position 46, TGA stop codon at position 469 and AATAAA polyadenylation signal at position 520. In G. denticulata, the cDNA is 536 bp with ATG start codon located at position 46, TGA stop codon at position 469 and AATAAA polyadenylation signal at position 517. Both cDNAs codify 141 amino acid residues, differing from each other in only four amino acid residues. When comparing with human Hb alpha-chain, alterations in important regions can be noted: alpha110 Ala-Gly, alpha114 Pro-Gly, alpha117 Phe-Tyr and alpha122 His-Gln. There is a high homology between the amino acids of these turtles when compared with chicken alpha-D chains, progressively decreasing when compared with human, crocodile, snake, frog and fish alpha-chains. Phylogenetic analysis of alpha-D chains shows that those of turtles are closer to those of birds than to snakes and lizards. (C) 2002 Elsevier B.V. All rights reserved.

THE EFFECT OF RECENT DIET ON PREY ODOR DISCRIMINATION BY JUVENILE TEGU LIZARD, TUPINAMBIS-TEGUIXIN (SAURIA, TEIIDAE)

Teiid lizards are intesive foragers supposed to rely lagerly on chemoreception for prey detection, an ability that can be modified by previous feeding experiences. We investigated the ability of juvenile lizards, Tupinambis teguixin, in discriminate prey from non-prey odors as well as the effects of recent diet on these ability. Tegu lizards were able to discriminate prey odors and this ability probably is inate. The effect of recent diet was analysed through optimal foraging models and our results does not support in a broad sense the predictions made by theoretical models.

Hypoxic pulmonary vasoconstriction in reptiles: a comparative study of four species with different lung structures and pulmonary blood pressures

Low O-2 levels in the lungs of birds and mammals cause constriction of the pulmonary vasculature that elevates resistance to pulmonary blood flow and increases pulmonary blood pressure. This hypoxic pulmonary vasoconstriction (HPV) diverts pulmonary blood flow from poorly ventilated and hypoxic areas of the lung to more well-ventilated parts and is considered important for the local matching of ventilation to blood perfusion. In the present study, the effects of acute hypoxia on pulmonary and systemic blood flows and pressures were measured in four species of anesthetized reptiles with diverse lung structures and heart morphologies: varanid lizards (Varanus exanthematicus), caimans (Caiman latirostris), rattlesnakes (Crotalus durissus), and tegu lizards (Tupinambis merianae). As previously shown in turtles, hypoxia causes a reversible constriction of the pulmonary vasculature in varanids and caimans, decreasing pulmonary vascular conductance by 37 and 31%, respectively. These three species possess complex multicameral lungs, and it is likely that HPV would aid to secure ventilation-perfusion homogeneity. There was no HPV in rattlesnakes, which have structurally simple lungs where local ventilation-perfusion inhomogeneities are less likely to occur. However, tegu lizards, which also have simple unicameral lungs, did exhibit HPV, decreasing pulmonary vascular conductance by 32%, albeit at a lower threshold than varanids and caimans (6.2 kPa oxygen in inspired air vs. 8.2 and 13.9 kPa, respectively). Although these observations suggest that HPV is more pronounced in species with complex lungs and functionally divided hearts, it is also clear that other components are involved.

The neuranatomical basis of central control of cardiorespiratory interactions in vertebrates

It seems that a dual location for vagal preganglionic neurones (VPNs) has important functional correlates in all vertebrates. This may be particularly the case with the central control exerted over the heart by cardiac VPNs (CVPNs). About 30 % of VPNs but up to 70 % of CVPNs are in the nucleus ambiguus (NA) of mammals. There is a similar proportional representation of VPNs between the major vagal nuclei in amphibians and turtles but in fish and crocodilians; the proportion of VPNs in the NA is closer to 10% and in some lizards and birds it is about 5%. However, the CVPNs are distributed unequally between these nuclei so that 45 % of the CVPNs are located in the NA of the dogfish, and about 30% in the NA of Xenopus and the duck. This topographical separation of CVPNs seems to be of importance in the central control of the heart. Cells in one location may show respiration-related activity (e.g those in the dorsal vagal nucleus (DVN) of dogfish and in the NA of mammals) while cells in the other locations do not. Their different activities and separate functions will be determined by their different afferent inputs from the periphery or from elsewhere in the CNS, which in turn will relate to their central topography. Thus, CVPNs in the NA of mammals receive inhibitory inputs from neighbouring inspiratory neurones, causing respiratory sinus arrythmia (RSA), and the CVPNs in the DVN of the dogfish may generate cardiorespiratory synchrony (CRS).