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.

Built to Bite: Feeding Kinematics, Bite Forces, and Head Shape of a Specialized Durophagous Lizard, Dracaena Guianensis (Teiidae)

Most lizards feed on a variety of food items that may differ dramatically in their physical and behavioral characteristics. Several lizard families are known to feed upon hard-shelled prey (durophagy). Yet, specializations toward true molluscivory have been documented for only a few species. As snails are hard and brittle food items, it has been suggested that a specialized cranial morphology, high bite forces, and an adapted feeding strategy are important for such lizards. Here we compare head and skull morphology, bite forces, and feeding kinematics of a snail-crushing teiid lizard (Dracaena guianensis) with those in a closely related omnivorous species (Tupinambis merianae). Our data show that juvenile D. guianensis differ from T. merianae in having bigger heads and greater bite forces. Adults, however, do not differ in bite force. A comparison of feeding kinematics in adult Dracaena and Tupinambis revealed that Dracaena typically use more transport cycles, yet are more agile in manipulating snails. During transport, the tongue plays an important role in manipulating and expelling shell fragments before swallowing. Although Dracaena is slow, these animals are very effective in crushing and processing hard-shelled prey. J. Exp. Zool. 317A:371381, 2012. (c) 2012 Wiley Periodicals, Inc.

Divergent calcium signaling in RBCs from Tropidurus torquatus (Squamata – Tropiduridae) strengthen classification in lizard evolution

Abstract Background We have previously reported that a Teiid lizard red blood cells (RBCs) such as Ameiva ameiva and Tupinambis merianae controls intracellular calcium levels by displaying multiple mechanisms. In these cells, calcium stores could be discharged not only by: thapsigargin, but also by the Na+/H+ ionophore monensin, K+/H+ ionophore nigericin and the H+ pump inhibitor bafilomycin as well as ionomycin. Moreover, these lizards possess a P2Y-type purinoceptors that mobilize Ca2+ from intracellular stores upon ATP addition. Results Here we report, that RBCs from the tropidurid lizard Tropidurus torquatus store Ca2+ in endoplasmic reticulum (ER) pool but unlike in the referred Teiidae, these cells do not store calcium in monensin-nigericin sensitive pools. Moreover, mitochondria from T. torquatus RBCs accumulate Ca2+. Addition of ATP to a calcium-free medium does not increase the [Ca2+]c levels, however in a calcium medium we observe an increase in cytosolic calcium. This is an indication that purinergic receptors in these cells are P2X-like. Conclusion T. torquatus RBCs present different mechanisms from Teiid lizard red blood cells (RBCs), for controlling its intracellular calcium levels. At T. torquatus the ion is only stored at endoplasmic reticulum and mitochondria. Moreover activation of purinergic receptor, P2X type, was able to induce an influx of calcium from extracelullar medium. These studies contribute to the understanding of the evolution of calcium homeostasis and signaling in nucleated RBCs.

Understanding the ecological niche to elucidate spatial strategies of the southernmost Tupinambis lizards

Understanding factors that shape ranges of species is central in evolutionary biology. Species distribution models have become important tools to test biogeographical, ecological and evolutionary hypotheses. Moreover, from an ecological and evolutionary perspective, these models help to elucidate the spatial strategies of species at a regional scale. We modelled species distributions of two phylogenetically, geographically and ecologically close Tupinambis species (Teiidae) that occupy the southernmost area of the genus distribution in South America. We hypothesized that similarities between these species might have induced spatial strategies at the species level, such as niche differentiation and divergence of distribution patterns at a regional scale. Using logistic regression and MaxEnt we obtained species distribution models that revealed interspecific differences in habitat requirements, such as environmental temperature, precipitation and altitude. Moreover, the models obtained suggest that although the ecological niches of Tupinambis merianae and T. rufescens are different, these species might co-occur in a large contact zone. We propose that niche plasticity could be the mechanism enabling their co-occurrence. Therefore, the approach used here allowed us to understand the spatial strategies of two Tupinambis lizards at a regional scale.

Differential staining and microchromosomal variation in karyotypes of four Brazilian species of Tupinambinae lizards (Squamata : Teiidae)

Kayotypes of four neotropical teiid lizard species (Tupinambinae) were herein studied after conventional as well as silver staining and CBG-banding: Crocodilurus amazonicus (2n = 34), Tupinambis teguixin (2n = 36), Tupinambis merianae and Tupinambis quadrilineatus (2n = 38). The karyological data for T. quadrilineatus as well as those obtained using differential staining for all species were unknown until now. The karyotypes of all species presented 12 macrochromosomes identical in morphology, but differed in the number of microchromosomes: 22 in C. amazonicus, 24 in T. teguixin and 26 in T. quadrilineatus and T. merianae. The Ag-NOR located at the secondary constriction at the distal end of pair 2 is shared by all species, contrasting with the variability observed for this character in species of the related Teiinae. CBG-banding revealed a species-specific pattern in T. quadrilineatus with conspicuous interstitial C-blocks at the proximal region of the long arm of pair 4 and the whole heterochromatic short arm of pair 6. The karyological data reported here corroborates the relationship hypothesis obtained for Tupinambis based on molecular characters. T. teguixin presents the putative ancestral karyotype for the genus with 2n = 36 whereas T. merianae and T. quadrilineatus exhibit 2n = 38, due to an additional pair of microchromosomes.

Helminths of Lizards (Reptilia: Squamata) from Mato Grosso State, Brazil

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

Helminths from Lizards (Reptilia: Squamata) at the Cerrado of Goias State, Brazil

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

Helminths from Seven Species of Lizards (Reptilia: Squamata) at the Cerrado of Mato Grosso do Sul State, Brazil

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

Linear Versus Geometric Morphometric Approaches for the Analysis of Head Shape Dimorphism in Lizards

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Diet of Procyon cancrivorus (Carnivora, Procyonidae) in restinga and estuarine environments of southern Brazil

Despite its wide range and abundance on certain habitats, the crab-eating raccoon Procyon cancrivorus (G. Cuvier, 1798) is considered one of the less known Neotropical carnivore species. In the present study we analyzed the diet of P. cancrivorus in a peat forest and in an estuarine island in southernmost Brazil. Fruits of the gerivá palm tree Syagrus romanzoffiana were the most consumed item in the peat forest, followed by insects and mollusks. Small mammals, followed by Bromelia antiacantha (Bromeliaceae) fruits and brachyuran crustaceans were the most frequent items in the estuarine island. Other items found in lower frequencies were Solanum sp., Psidium sp., Smilax sp. and Dyospiros sp. fruits, diplopods, scorpions, fishes, anuran amphibians, reptiles (black tegu lizard and snakes), birds and medium-sized mammals (white-eared opossum, armadillo and coypu). Levin’s index values (peat forest: 0.38; estuarine island: 0.45) indicate an approximation to a median position between a specialist and a well distributed diet. Pianka’s index (0.80) showed a considerable diet similarity between the two systems. Procyon cancrivorus presented a varied diet in the studied areas and may play an important role as seed disperser on coastal environments in southernmost Brazil.

Domestic, peridomestic and wild hosts in the transmission of Trypanosoma cruzi in the Caatinga area colonised by Triatoma brasiliensis

The role played by different mammal species in the maintenance of Trypanosoma cruzi is not constant and varies in time and place. This study aimed to characterise the importance of domestic, wild and peridomestic hosts in the transmission of T. cruzi in Tauá, state of Ceará, Caatinga area, Brazil, with an emphasis on those environments colonised by Triatoma brasiliensis. Direct parasitological examinations were performed on insects and mammals, serologic tests were performed on household and outdoor mammals and multiplex polymerase chain reaction was used on wild mammals. Cytochrome b was used as a food source for wild insects. The serum prevalence in dogs was 38% (20/53), while in pigs it was 6% (2/34). The percentages of the most abundantly infected wild animals were as follows: Thrichomys laurentius 74% (83/112) and Kerodon rupestris 10% (11/112). Of the 749 triatomines collected in the household research, 49.3% (369/749) were positive for T. brasiliensis, while 6.8% were infected with T. cruzi (25/369). In captured animals, T. brasiliensis shares a natural environment with T. laurentius, K. rupestris, Didelphis albiventris, Monodelphis domestica, Galea spixii, Wiedomys pyrrhorhinos, Conepatus semistriatus and Mus musculus. In animals identified via their food source, T. brasiliensis shares a natural environment with G. spixii, K. rupestris, Capra hircus, Gallus gallus, Tropidurus oreadicus and Tupinambis merianae. The high prevalence of T. cruzi in household and peridomiciliar animals reinforces the narrow relationship between the enzootic cycle and humans in environments with T. brasiliensis and characterises it as ubiquitous.

Necrophagous diptera associated with wild animal carcasses in southern Brazil

Necrophagous Diptera associated with wild animal carcasses in southern Brazil. The aim of this study was to acquire a better knowledge concerning the diversity of necrophagous Diptera that develop on wild animal carcasses. For this purpose, the decomposition of six wild animal carcasses was observed in order to collect and identify the main species of necrophagous flies associated with the decomposition process. The carcasses were found on highways near the cities of Pelotas and Capão do Leão in the initial stage of decomposition, with no significant injuries or prior larval activity. Four wild animal models were represented in this study: two specimens of Didelphis albiventris Lund, 1840; two Tupinambis merianae Linnaeus, 1758; one Nothura maculosa Temminck, 1815; and one Cerdocyon thous Linnaeus, 1766. A total of 16,242 flies from 14 species were reared in the laboratory, where Muscidae presented the greatest diversity of necrophagous species. Overall, (i) carcasses with larger biomass developed a higher abundance of flies and (ii) the necrophagous community was dominated by Calliphoridae, two patterns that were predicted from published literature; and (iii) the highest diversity was observed on the smaller carcasses exposed to the lowest temperatures, a pattern that may have been caused by the absence of the generalist predator Chrysomya albiceps (Wiedemann, 1819). (iv) An UPGMA analysis revealed a similar pattern of clusters of fly communities, where the same species were structuring the groupings.

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.

Levantamento das espécies de répteis da área da Escola do Meio Ambiente, Botucatu/SP

No Brasil, o estado de São Paulo se destaca como sendo um dos principais centros de estudos sobre a herpetofauna. A fauna de anfíbios da região de Botucatu é, talvez, uma das melhores conhecidas do Brasil, devido ao grande número de estudos realizados. Por outro lado, pouco se conhece sobre a fauna de répteis dessa região. A realização de um trabalho com esse grupo mostra-se de fundamental importância para o conhecimento da fauna local, bem como das relações das espécies com o ambiente. Buscando preencher essa lacuna, o presente trabalho teve como objetivo caracterizar a fauna de répteis em uma área de mosaico vegetacional, quanto a composição, riqueza e aos padrões de distribuição sazonal e espacial das espécies registradas. O trabalho foi realizado na Escola do Meio Ambiente/EMA (22º55’23”S e 48º27’28”W), localizada no município de Botucatu, SP. A área apresenta remanescentes de mata (Floresta Estacional Semidecidual, Floresta Paludosa) e uma pequena área de formação campestre (campo sujo). O período de estudo foi entre os meses de Março de 2010 e Fevereiro de 2011, com visitas quinzenais, com duração de quatro dias cada, totalizando noventa e seis dias de amostragem. O levantamento foi realizado utilizando-se três métodos: busca ativa, armadilhas de interceptação e queda e encontro ocasional. Dados adicionais foram obtidos a partir do exame em coleções científicas e no acervo de imagens da escola. Quatorze espécies foram inventariadas, sendo sete lagartos, seis serpentes e um anfisbenídeo distribuídos em nove famílias: Amphisbaenidae (Amphisbaena alba), Polychrotidae (Polychrus acutirostris), Leiosauridae (Enyalius perditus), Tropiduridae (Tropidurus torquatus), Gekkonidae (Hemidactylus mabouia), Teiidae (Tupinambis merianae), Gymnophthalmidae (Cercosaura ocellata), Scincidae (Mabuya dorsivitatta), ...(Resumo completo, clicar acesso eletrônico abaixo)

Tegu (teiu) bite: Report of human injury caused by a Teiidae lizard

Lizards of the Teiidae family are large reptiles measuring up to 2 meters long. If threatened, they can demonstrate aggressive behavior by whipping their tail and occasionally biting. Here, we report a severe injury following a Teiidae lizard bite on the right index finger of a human. There was significant soft tissue damage and an avulsion fracture of the distal phalanx. He was treated with conservative wound care and prophylactic antibiotics. He developed no evidence of secondary infection and underwent delayed skin grafting.