Abstract Hibernation is a natural condition of animals that lives in the temperate zone, although some tropical lizards also experience hibernation annually, such as the lizard native from South America, Salvator merianae, or "tegu" lizard. Even though physiological and metabolic characteristic associated with hibernation have been extensively studied, possible alterations in the red blood cells (RBC) integrity during this period remains unclear. Dehydration and fasting are natural consequences of hibernating for several months and it could be related to some cellular modifications. In this study, we investigated if the osmotic tolerance of RBCs of tegu lizard under hibernation is different from the cells obtained from animals while normal activity. Additionally, we indirectly investigated if the RBCs membrane of hibernating tegus could be associated with oxidation by quantifying oxidized biomolecules and the activity of antioxidant enzymes. Our findings suggest that RBCs are more fragile during the hibernation period, although we did not find evidence of an oxidative stress scenario associated with the accentuated fragility. Even though we did not exclude the possibility of oxidative damage during hibernation, we suggested that an increased RBCs volume as a consequence of hypoosmotic blood during hibernation could also affect RBCs integrity as noted.
Resumo A hibernação é uma condição natural dos animais que vivem na zona temperada, embora alguns lagartos tropicais também experenciem hibernação anualmente, como é o caso do lagarto nativo da América do Sul, Salvator merianae ou "teiú". Embora as características fisiológicas e metabólicas associadas à hibernação tenham sido amplamente estudadas, possíveis alterações na integridade das hemácias durante esse período ainda permanecem obscuras. A desidratação e o jejum são consequências naturais da hibernação por vários meses e podem estar relacionadas a algumas modificações celulares. Neste estudo, investigamos se a tolerância osmótica de hemácias do lagarto teiú sob hibernação são diferentes das células obtidas de animais em atividade normal. Além disso, investigamos indiretamente por meio da quantificação de biomoléculas oxidadas e da atividade de enzimas antioxidantes se a membrana das hemácias dos teiús em hibernação poderia estar associada à oxidação. Nossos resultados sugerem que as hemácias possuem maior fragilidade durante o período de hibernação, embora não tenhamos encontrado evidências de um cenário de estresse oxidativo associado à essa fragilidade acentuada. Embora não tenhamos excluído a possibilidade de dano oxidativo durante a hibernação, sugerimos que um aumento no volume das hemácias como consequência de sangue hipoosmótico durante a hibernação também poderia afetar a integridade de hemácias, tal como foi observado.
AssuntosAnimais , Hibernação , Lagartos , Oxirredução , Estresse Oxidativo , Eritrócitos
Abstract During the present study, specimens were collected from selected sites of Cholistan desert and Kalabagh Game Reserve, Punjab province, Pakistan. Each captured specimen was tagged with voucher number and morphometric measurements were taken. The average snout to vent length was 172.559±1.40 mm and average weight was 92.1±1.30 g. The DNA of Uromastyx hardwickii was amplified and sequenced using 16S rRNA primer set. The obtained DNA sequence has shown reliable and clear species identification. After trimming ambiguous bases, the obtained 16S rRNA fragment was 520 bp while 16S rRNA fragments aligned with closely matched sequence from NCBI comprised of 510 bp. Closely matched sequences of genus Uromastyx were retrieved from NCBI in blast searches. Neighbour-joining tree of genus Uromastyx was constructed based on p-distance using MEGA X. The mean intraspecific variation was 0.095±0.01 while intraspecific variation was ranging from 0-1%. Similarly, interspecific variation of Uromastyx hardwikii with Saara asmussi, Uromastyx alfredschmidti, Uromastyx geyri, Uromastyx thomasi, Uromastyx alfredschmidti was 0-12%, 0-19%, 0-19%, 0-20%, 12-19% respectively. The newly produced DNA was submitted to NCBI and accession number was obtained (MW052563.1). Results of current study provided information about the molecular and morphological identification of Genus Uromastyx. In our recommendation, comprehensive molecular based identification of Pakistan's reptiles is required to report any new or subspecies from country.
Resumo Durante o presente estudo, os espécimes foram coletados em locais selecionados do deserto do Cholistan e da Reserva de Caça de Kalabagh, província de Punjab, Paquistão. Cada espécime capturado foi etiquetado com o número do comprovante e medidas morfométricas foram realizadas. O comprimento médio do focinho à cloaca foi de 172,559 ± 1,40 mm, e o peso médio foi de 92,1 ± 1,30 g. O DNA de Uromastyx hardwickii foi amplificado e sequenciado usando o conjunto de primer 16S rRNA. A sequência de DNA obtida mostrou identificação de espécies confiável e clara. Após o corte de bases ambíguas, o fragmento de rRNA 16S obtido tinha 520 pb, enquanto os fragmentos de rRNA 16S alinhados com a sequência próxima do NCBI composta por 510 pb. Sequências semelhantes do gênero Uromastyx foram recuperadas do NCBI em pesquisas de explosão. A árvore de união de vizinhos do gênero Uromastyx foi construída com base na distância-p usando MEGA X. A variação intraespecífica média foi de 0,095 ± 0,01, enquanto a variação intraespecífica foi de 0-1%. Da mesma forma, a variação interespecífica de Uromastyx hardwikii com Saara asmussi, Uromastyx alfredschmidti, Uromastyx geyri, Uromastyx thomasi, Uromastyx alfredschmidti foi de 0-12%, 0-19%, 0-19%, 0-20%, 12-19%, respectivamente. O DNA recém-produzido foi submetido ao NCBI e o número de acesso foi obtido (MW052563.1). Os resultados do estudo atual forneceram informações sobre a identificação molecular e morfológica do Gênero Uromastyx. Em nossa recomendação, a identificação de base molecular abrangente de répteis do Paquistão é necessária para relatar qualquer nova ou subespécie do país.
AssuntosAnimais , Lagartos , Paquistão , Filogenia , Variação Genética/genética , RNA Ribossômico 16S
AssuntosAnimais , Pentastomídeos , Lagartos , Brasil , Bufonidae
Present research work represents antiviral and antibacterial value of body fat of Saara hardwickii commonly called as spiny tailed lizard. Oil was extracted from body fats located in the ventral region of this animal using hydrocarbons e.g., n-hexane, methanol, butanol and ethyl acetate as a solvent. The antibacterial activity of lizard oil was tested against standard as well as multi-resistant lines ofEscherichia coli, Styphalococcus aureus, Pseudomonas aeruginosa and Proteus vulgaris alone and with antibiotic ampicillin. For antibacterial potential, Ethyl acetate and Butanol solvent extract showed best zone of inhibition (7mm) with P. aeruginosa and S. aureus respectively. For antiviral potential, Butanol and Methanol extract showed best HA (Hemagglutination) titer of 04 with NDV and IBV viral strain respectively. It is concluded that lizard oil has antimicrobial potential against different pathogens strains (virus, bacteria).
O presente trabalho de pesquisa apresenta a importância antiviral e antibacteriana da gordura corporal de Saara hardwickii, comumente chamado de lagarto de cauda espinhosa. O óleo foi extraído de gorduras corporais localizadas na região ventral desse animal usando hidrocarbonetos, por exemplo, n-hexano, metanol, butanol e acetato de etila, como solvente. A atividade antibacteriana do óleo do lagarto foi testada em linhagens padrão e multirresistentes de Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa e Proteus vulgaris, de forma isolada e com antibiótico ampicilina. Para o potencial antibacteriano, acetato de etila e extrato de butanol apresentaram melhor zona de inibição (7 mm) com P. aeruginosa e S. aureus, respectivamente. Para o potencial antiviral, o extrato de butanol e o extrato de metanol apresentaram melhor título de hemaglutinação de 4 com as cepas virais NDV e IBV, respectivamente. Conclui-se que o óleo do lagarto possui potencial antimicrobiano contra diferentes cepas de patógenos (vírus e bactérias).
AssuntosAnimais , Antivirais , Tecido Adiposo , Lagartos , Antibacterianos
Background: Host-gut microbiota interactions are complex and can have a profound impact on the ecology and evolution of both counterparts. Several host traits such as systematics, diet and social behavior, and external factors such as prey availability and local environment are known to influence the composition and diversity of the gut microbiota. Methods: In this study, we investigate the influence of systematics, sex, host size, and locality/habitat on gut microbiota diversity in five lizard species from two different sites in Portugal: Podarcis bocagei and Podarcis lusitanicus, living in syntopy in a rural area in northern Portugal (Moledo); the invasive Podarcis siculus and the native Podarcis virescens, living in sympatry in an urbanized environment (Lisbon); and the invasive Teira dugesii also living in an urban area (Lisbon). We also infer the potential microbial transmission occurring between species living in sympatry and syntopy. To achieve these goals, we use a metabarcoding approach to characterize the bacterial communities from the cloaca of lizards, sequencing the V4 region of the 16S rRNA. Results: Habitat/locality was an important factor explaining differences in gut bacterial composition and structure, with species from urbanized environments having higher bacterial diversity. Host systematics (i.e., species) influenced gut bacterial community structure only in lizards from the urbanized environment. We also detected a significant positive correlation between lizard size and gut bacterial alpha-diversity in the invasive species P. siculus, which could be due to its higher exploratory behavior. Moreover, estimates of bacterial transmission indicate that P. siculus may have acquired a high proportion of local microbiota after its introduction. These findings confirm that a diverse array of host and environmental factors can influence lizards' gut microbiota.
AssuntosMicrobioma Gastrointestinal , Lagartos , Microbiota , Animais , Microbioma Gastrointestinal/genética , Lagartos/genética , RNA Ribossômico 16S/genética , Comportamento Social , Bactérias
Biological specialization reduces the size of niche space while increasing efficiency in the use of available resources. Specialization often leads to phenotypic changes via natural selection aligning with niche space constraints. Commonly observed changes are in size, shape, behavior, and traits associated with feeding. One often selected trait for dietary specialization is venom, which, in snakes, often shows variation dependent on diet across and within species. The Neotropical Blunt-headed Treesnake (Imantodes cenchoa) is a highly specialized, rear-fanged, arboreal, lizard hunter that displays a long thin body, enlarged eyes, and a large Duvernoy's gland. However, toxin characterization of I. cenchoa has never been completed. Here, we use RNA-seq and mass spectrometry to assemble, annotate, and analyze the venom gland transcriptomes of four I. cenchoa from across their range. We find a lack of significant venom variation at the sequence and expression levels, suggesting venom conservation across the species. We propose this conservation provides evidence of a specialized venom repertoire, adapted to maximize efficiency of capturing and processing lizards. Importantly, this study provides the most complete venom gland transcriptomes of I. cenchoa and evidence of venom specialization in a rear-fanged snake, giving insight into selective pressures of venom across all snake species.
AssuntosColubridae , Lagartos , Toxinas Biológicas , Animais , Venenos de Serpentes/química , Lagartos/metabolismo , Colubridae/genética , Colubridae/metabolismo , Toxinas Biológicas/metabolismo , Fenótipo
This paper considers the effects of claw morphology on the gripping efficiency of arboreal (Varanus varius) and burrowing (Varanus gouldii and Varanus panoptes) lizards. To ensure a purely morphological comparison between the lizards, we circumvent the material effects of claws from different species, by modelling and testing claw replicates of the same material properties. We correlate climbing efficiency to critical morphological features including; claw height (hc), width (wc), length (lc), curvature () and tip angle (Î³), which are expressed as ratios to normalise mechanically beneficial claw structures. We find that there is strong correlation between the static grip force Fsg and the claw aspect and the cross-sectional rigidity ratio , and milder correlation (i.e. higher scatter) with the profile rigidity ratio . These correlations are also true for the interlocking grip force Fint over different shaped and sized protuberances, though we note that certain protuberance size-shape couplings are of detriment to the repeatability of Fint. Of the three lizard species, the claws of the arboreal (V. varius) are found to be superior to those of the burrower lizards (V. gouldii and V. panoptes) as a result of the V. varius claws having a smaller aspect, a higher cross-sectional rigidity ratio and a small profile rigidity ratio, which are deemed noteworthy morphological parameters that influence a claw's ability to grip effectively.
AssuntosCasco e Garras , Lagartos , Animais , Estudos Transversais
Developmental conditions can profoundly impact key life history traits of the individual. In cases where offspring sex is driven by developmental reaction norms, permanent changes to the phenotype can fundamentally alter life history trajectories. Sex determination mechanisms in reptiles are remarkably diverse, including well-characterised genetic and temperature-dependent sex determination. In rarer, but increasingly more commonly documented cases, sex can also be determined by a combination of the two, with temperature overriding the genetically determined sex. Thus, sex-by-temperature interactions is a mechanism that can be contextually labile, where reaction norms of sex against developmental environment might only be observable under certain conditions. We examine the effects of incubation temperature on hatchling sex in an oviparous lizard with clearly defined heteromorphic sex chromosomes presumed to determine sex solely on a genetic basis. We also test the repeatability of our results by replicating incubation experiments across 3 years. We show that warmer temperatures may override chromosomal sex and cause an overproduction of daughters. However, this effect was inconsistent among years, with high temperature only resulting in a daughter-significant bias in one year. Warm-incubated daughters were more efficient at converting yolk into tissue, which would allow for greater resource allocation to other fitness-related processes, such as growth. This suggests that thermolabile sex determination could be a trait under selection. More energy-efficient embryos also produced faster-growing offspring, suggesting that energy utilization patterns of the embryo were maintained into the juvenile stage, which could have important implications for the ontogenetic development and evolution of life histories.
AssuntosLagartos , Processos de Determinação Sexual , Animais , Lagartos/genética , Temperatura , Temperatura Alta , Cromossomos Sexuais/genética
The kukri snakes of the genus Oligodon Fitzinger, 1826 reach the westernmost limits of their distribution in Middle and Southwest Asia (Afghanistan, Iran, and Turkmenistan), and the Palearctic portions of Pakistan. In this article, we review the systematics and distribution of the two species native to this region, Oligodon arnensis (Shaw, 1802) and Oligodon taeniolatus (Jerdon, 1853) based on an integrative approach combining morphological, molecular, and species distribution modeling (SDM) data. Phylogenetic analyses recover O. taeniolatus populations from Iran and Turkmenistan in a clade with the O. arnensis species complex, rendering the former species paraphyletic relative to O. taeniolatus sensu stricto on the Indian subcontinent. To correct this, we resurrect the name Contia transcaspica Nikolsky, 1902 from the synonymy of O. taeniolatus and assign it to populations in Middle-Southwest Asia. So far, Oligodon transcaspicus comb. et stat. nov. is known only from the Köpet-Dag Mountain Range of northeast Iran and southern Turkmenistan, but SDM mapping suggests it may have a wider range. Genetic samples of O. "arnensis" from northern Pakistan are nested in a clade sister to the recently described Oligodon churahensis Mirza, Bhardwaj & Patel, 2021, and are phylogenetically separate from O. arnensis sensu stricto in south India and Sri Lanka. Based on morphological similarity, the Afghanistan and Pakistan populations are assigned to Oligodon russelius (Daudin, 1803) and we synonymize O. churahensis with this species. Our investigation leads us to remove O. taeniolatus from the snake fauna of Afghanistan, Iran, and Turkmenistan, with the consequence that only Oligodon transcaspicus comb. et stat. nov. and O. russelius are present in these countries. Additional studies are needed to resolve the taxonomy of the O. taeniolatus and O. arnensis species complexes on the Indian subcontinent, and an updated key for both groups is provided.
AssuntosCheirogaleidae , Colubridae , Lagartos , Animais , Filogenia , Irã (Geográfico) , Afeganistão
Locomotor impairment during pregnancy is a well-documented cost of reproduction, but most empirical studies have not incorporated ecological complexity, such as locomotion on sloping inclines rather than horizontal surfaces. Biomechanical factors suggest that carrying a heavy burden-including shifts in the body's centre of mass-may impair locomotor ability even more when an animal is running uphill. If so, then measuring costs of reproduction on horizontal racetracks may underestimate these costs in nature for arboreal species. To evaluate this prediction, we measured the pregnancy-induced reduction in speed for jacky dragons (Amphibolurus muricatus) at inclines ranging from 0 to 45°. Both pregnancy and steeper slopes reduced lizard performance, but pregnancy did not exacerbate the locomotor decrement on steeper racetracks. An ability to maintain mobility on steep slopes during pregnancy may be a target of selection in arboreal taxa. To understand the evolutionary context of locomotion-based costs of reproduction, we also need studies on the relationship between organismal performance and ecologically relevant measures such as predation risk.
AssuntosLagartos , Reprodução , Animais , Feminino , Evolução Biológica , Cânfora , Locomoção , Árvores
On a global scale, organisms face significant challenges due to climate change and anthropogenic disturbance. In many ectotherms, developmental and physiological processes are sensitive to changes in temperature and resources. Developmental plasticity in thermal physiology may provide adaptive advantages to environmental extremes if early environmental conditions are predictive of late-life environments. Here, we conducted a laboratory experiment to test how developmental temperature and maternal resource investment influence thermal physiological traits (critical thermal maximum: CTmax and thermal preference: Tpref) in a common skink (Lampropholis delicata). We then compared our experimental findings more broadly across reptiles (snakes, lizards and turtles) using meta-analysis. In both our experimental study and meta-analysis, we did not find evidence that developmental environments influence CTmax or Tpref. Furthermore, the effects of developmental environments on thermal physiology did not vary by age, taxon or climate zone (temperate/tropical). Overall, the magnitude of developmental plasticity on thermal physiology appears to be limited across reptile taxa suggesting that behavioural or evolutionary processes may be more important. However, there is a paucity of information across most reptile taxa, and a broader focus on thermal performance curves themselves will be critical in understanding the impacts of changing thermal conditions on reptiles in the future.
AssuntosLagartos , Tartarugas , Animais , Evolução Biológica , Mudança Climática , Fenótipo
Skin provides functions such as protection and prevention of water loss. In some taxa, the outer surface of skin has been modified to form structures that enable attachment to various surfaces. Constant interaction with surfaces is likely to cause damage to these attachment systems and reduce function. It seems logical that when skin is shed via ecdysis, its effectiveness will increase, through repair of damage or other rejuvenating mechanisms. We address two questions using three diplodactylid geckos as model species. (1) Does repeated mechanical damage affect clinging ability in geckos to the point that they cannot support their own body weight? (2) Does use without induced damage reduce effectiveness of the attachment system, and if so, does ecdysis restore clinging ability? We found that repeated damage reduced clinging ability in all three species, although at different rates. Additionally, use reduced clinging ability over time when no apparent damage was incurred. Clinging ability increased after ecdysis in all three species, both when damage was specially induced, and when it was not. After normal use without induced damage, the increase in clinging ability after ecdysis was statistically significant in two of three species. Our findings show that use decreases clinging ability, and mechanical damage also effects geckos' capacity to exert shear forces consistently. Thus, ecdysis improves clinging ability both in scenarios where damage is induced and more generally. In addition to the physiological functions provided by skin, our study highlights an important function of ecdysis in a speciose vertebrate group.
AssuntosLagartos , Animais , Lagartos/fisiologia , Muda , Pele , Gravitação
BACKGROUND: The use of complementary and/or alternative medicine to increase the efficacy and decrease the side effects of current cancer treatment is highly required. In this in-vivo study, we aimed to investigate the anti-tumor activity and probable side effects of a natural treatment, Cyrtopodion scabrum extract (CsE), in a model of tumor bearing mice. METHODS: We established 28 female CT26-tumor bearing balb/c-mice model. We divided them randomly into four groups (n=7): Negative control received distilled water (DW) and the three treatment groups were administered with 5-FU and two different doses (300 and 600 mg/kg) of the gecko aqueous extract, respectively. The changes in the tumor volumes and weights during and after treatment, along with the blood cell counts; spleen and thymus indices were assessed in the treatment groups. We have also measured the serum TNF-α, VEGF, AST, ALT and GSH, as well as the physical activities of the experimental mice. RESULTS: We found that the means of tumor weights and volumes in both CsE and 5-FU treated groups were significantly lower than the untreated group (p<0.05). Serum TNF-α and VEGF levels in both CsE treated groups were remarkably lower than 5-FU and untreated groups (p<0.05). The 5-FU treatment caused a remarkably decrease in serum GSH, RBC count, WBC count, thymus index, and spleen index , while CsE treatment maintained these quantities, with no significant changes, compared to the control group. AST and ALT were not significantly changed in none of the treated groups compared to control. CONCLUSION: Altogether, data suggest C. scabrum, as an effective and safe anti-cancer natural source, which could be used as an alternative/complementary medicine for the treatment of patients who suffer from colon cancer.
AssuntosNeoplasias do Colo , Lagartos , Feminino , Camundongos , Animais , Fluoruracila/farmacologia , Fluoruracila/uso terapêutico , Fator A de Crescimento do Endotélio Vascular , Fator de Necrose Tumoral alfa , Neoplasias do Colo/tratamento farmacológico , Anti-Inflamatórios , Camundongos Endogâmicos BALB C
The complex orogenic history and structure of Central Asia, coupled with Pleistocene glacial cycles have generated its stepwise aridification. Such events would have significantly influenced the evolution of many mid-latitude species in arid Central Asia (ACA). In this study, we employed two mitochondrial genes (CO1 and ND2) and genome-wide SNPs, coupled with ecological niche modeling, to investigate the lineage diversification and historical demography within a widespread lizard Phrynocephalus helioscopus, and their associations with geography and past climate change. We obtained the mtDNA dataset for 300 individuals from 96 localities within the known range of the lizard, among which 51 individuals from 27 localities were selected for generating the SNP dataset via the genotyping-by-sequencing approach. Phylogenetic analyses of the concatenated mtDNA dataset revealed eight geographically correlated lineages that diverged by 4.21-10.41% for the CO1 gene, which were estimated to have coalesced â¼4.47 million years ago. However, we observed mito-nuclear discordance pattern regarding the population of Clade V (P. helioscopus sergeevi) from Tajikistan. Ancestral area estimations suggested that P. helioscopus originated from the Fergana Valley and then dispersed into the adjacent areas in ACA along with a history of multiple allopatric divergence processes, suggesting that Fergana may have been the cradle of diversification of P. helioscopus. The intensification of aridification across Central Asia during the Late Pliocene may have facilitated the rapid radiation of this arid-adapted lizard throughout this vast territory. Subsequently, the geological events (e.g., uplift of the Hissar-Alay, transgressions of the Caspian Sea) and geographic barriers (e.g., Amu Darya River, Zeravshan River) during the Pleistocene triggered the progressive diversification of P. helioscopus. Interestingly, Clade VIII (P. helioscopus varius) experienced rapid population growth coupled with range expansion while Clade IV (P. helioscopus cameranoi) underwent drastic population expansion associated with range contraction during the Last Glacial Maximum. In Clade IV, but not in Clade VIII, environmental turnover contributes more to mitochondrial genetic distinctiveness than geographic distance. Overall, the SNP dataset demonstrates that geographic distance plays a greater role than environmental distance. Both the mtDNA dataset and the SNP dataset suggest local-scale genetic differentiation in Clade IV and Clade VIII, revealing potential geographic barriers in the Ili River Valley and the Junggar Basin, respectively. Twenty-seven outlier SNPs associated with environmental factors (precipitation and temperature) were identified, which supports the signature of local adaptation to the arid desert environment. Finally, our finding suggests taxonomic implications, such as support for full species status for P. saidalievi (Clade II) and P. meridionalis (Clade I). Future analyses based on further evidence and increased taxon and geographic sampling should be carried out to corroborate our findings.
AssuntosLagartos , Humanos , Animais , Filogenia , Lagartos/genética , Mudança Climática , Geografia , DNA Mitocondrial/genética , Ásia , Filogeografia , Variação Genética
High altitude environments provide a fertile ground for investigating the benefits of phenotypic adjustments at several levels of biological organization. Low oxygen partial pressure and low environmental temperature are the main limiting factors that promote phenotypic variation in different organs, such as the lung and heart. Although high-altitude environments act like natural laboratories, most morphological studies conducted to date lack replication. Here, we evaluated organ mass variation in nine populations of Sceloporus grammicus, throughout three altitudinal gradients (mountains) from the Trans-Mexican volcanic belt. A total of 84 individuals from three different altitudes at three different mountains were collected. Then, we used generalized linear models to analyze the pattern of variation in internal organs mass as a function of altitude and temperature. We observed a striking pattern of altitudinal variation in the size of cardiorespiratory organs: while heart mass increased with altitude and decreased with temperature, the lung showed a significant statistical interaction between mountain transect and temperature. Overall, our results support the hypothesis that cardiorespiratory organs should be bigger in populations occurring at higher altitudes. Moreover, the study of different mountain systems allowed us to observe some differences in one mountain in relation to the other two.
AssuntosLagartos , Prosopis , Humanos , Animais , Altitude , Temperatura , Temperatura Baixa
Herein we review our work involving dispersed adrenocortical cells from several lizard species: the Eastern Fence Lizard (Sceloporus undulatus), Yarrow's Spiny Lizard (Sceloporus jarrovii), Striped Plateau Lizard (Sceloporus virgatus) and the Yucatán Banded Gecko (Coleonyx elegans). Early work demonstrated changes in steroidogenic function of adrenocortical cells derived from adult S. undulatus associated with seasonal interactions with sex. However, new information suggests that both sexes operate within the same steroidogenic budget over season. The observed sex effect was further explored in orchiectomized and ovariectomized lizards, some supported with exogenous testosterone. Overall, a suppressive effect of testosterone was evident, especially in cells from C. elegans. Life stage added to this complex picture of adrenal steroidogenic function. This was evident when sexually mature and immature Sceloporus lizards were subjected to a nutritional stressor, cricket restriction/deprivation. There were divergent patterns of corticosterone, aldosterone, and progesterone responses and associated sensitivities of each to corticotropin (ACTH). Finally, we provide strong evidence that there are multiple, labile subpopulations of adrenocortical cells. We conclude that the rapid (days) remodeling of adrenocortical steroidogenic function through fluctuating cell subpopulations drives the circulating corticosteroid profile of Sceloporus lizard species. Interestingly, progesterone and aldosterone may be more important with corticosterone serving as essential supportive background. In the wild, the flux in adrenocortical cell subpopulations may be adversely susceptible to climate-change related disruptions in food sources and to xenobiotic/endocrine-disrupting chemicals. We urge further studies using native lizard species as bioindicators of local pollutants and as models to examine the broader eco-exposome.
AssuntosCorticosterona , Lagartos , Masculino , Feminino , Animais , Aldosterona , Progesterona , Caenorhabditis elegans , Lagartos/fisiologia , Hormônio Adrenocorticotrópico , Aves , Testosterona
The relationship between sublethal pesticide exposure and oxidative stress in an ecologically relevant field setting is relatively unknown for reptiles. Oxidative stress is a multi-faceted concept that dictates key survival and fitness parameters in any organism. Fipronil and fenitrothion are two pesticides widely used globally for agricultural pest management. Using a field-based, BACI designed experiment we investigated the impact of sublethal pesticide exposure on oxidative stress biomarkers protein carbonyl and DNA damage (8-OHdG), in an arid-zone lizard species, Pogona vitticeps. A single ecologically relevant dose of pesticide was applied via oral gavage to treatment animals. Lizard condition, activity measures, and blood biomarkers were measured at relevant sampling intervals. Cholinesterase (ChE) and acetylcholinesterase (AChE) enzymatic biomarkers were measured in response to fenitrothion, and fipronil blood residues were measured for fipronil-treated lizards. Results suggested no significant treatment effect of either pesticide on parameters measured, however, 8-OHdG levels decreased by ≥ 45% for both pesticide treatment groups and not controls. Protein carbonyl levels showed a high degree of individual variation that proved more influential than pesticide exposure. Building our understanding of the macromolecular impacts of sublethal pesticide exposure on wild lizard populations is an integral step in addressing the current gap in literature and management practices. Our study has also highlighted the complex nature of studying oxidative stress in the field and the sheer necessity of future study.
AssuntosLagartos , Praguicidas , Animais , Praguicidas/toxicidade , Acetilcolinesterase/metabolismo , Fenitrotion , Lagartos/metabolismo , Estresse Oxidativo , Biomarcadores/metabolismo
Many animals undergo changes in functional colors during development, requiring the replacement of integument or pigment cells. A classic example of defensive color switching is found in hatchling lizards, which use conspicuous tail colors to deflect predator attacks away from vital organs. These tail colors usually fade to concealing colors during ontogeny. Here, we show that the ontogenetic blue-to-brown tail color change in Acanthodactylus beershebensis lizards results from the changing optical properties of single types of developing chromatophore cells. The blue tail colors of hatchlings are produced by incoherent scattering from premature guanine crystals in underdeveloped iridophore cells. Cryptic tail colors emerge during chromatophore maturation upon reorganization of the guanine crystals into a multilayer reflector concomitantly with pigment deposition in the xanthophores. Ontogenetic changes in adaptive colors can thus arise not via the exchange of different optical systems, but by harnessing the timing of natural chromatophore development. The incoherent scattering blue color here differs from the multilayer interference mechanism used in other blue-tailed lizards, indicating that a similar trait can be generated in at least two ways. This supports a phylogenetic analysis showing that conspicuous tail colors are prevalent in lizards and that they evolved convergently. Our results provide an explanation for why certain lizards lose their defensive colors during ontogeny and yield a hypothesis for the evolution of transiently functional adaptive colors.
AssuntosCromatóforos , Lagartos , Animais , Filogenia , Pigmentação , Pele
BACKGROUND: The Manapany day gecko (Phelsuma inexpectata) is endemic to the south of Reunion Island. Threatened by habitat fragmentation and loss, human activities and invasive species, P. inexpectata is considered as critically endangered. Conservation measures are required but data on the species are missing, notably on its genetic diversity and population structure for which no specific markers are available to date. Here, we aimed to develop molecular markers to allow genetic studies of P. inexpectata. METHODS AND RESULTS: We developed and characterized 20 polymorphic microsatellite markers based on 23 P. inexpectata individuals sampled from 10 sites. Then, the markers were tested on a total of 101 individuals, 30 from a natural site and 71 from an anthropized site. The mean values of Na, Ho and He were 2.3 (± 0.2), 0.353 (± 0.053) and 0.345 (± 0.046) in the natural site and 2.8 (± 0.3), 0.345 (± 0.051) and 0.338 (± 0.048) in the anthropized site, respectively. Based on the combined loci, the probability of identity (PID) for unrelated specimens were 2.7 × 10-7 and 2.6 × 10-7 in the natural and anthropized site, respectively. CONCLUSIONS: This work provides the first set of microsatellite markers for P. inexpectata, constituting a valuable tool to conduct classical genetic studies on the species, such as estimating genetic diversity, population structure and kinship relationships among individuals. Such studies will provide relevant information on P. inexpectata and will therefore be helpful in the implementation of conservation measures for this threatened species.
AssuntosEspécies em Perigo de Extinção , Lagartos , Animais , Humanos , Reunião , Lagartos/genética , Repetições de Microssatélites/genética , Ecossistema
Osteoderms, also called dermal armour, often play a role in predator defence. The presence of osteoderms is highly irregularly distributed across the squamate phylogeny and they have not been found in snakes. In this study, we searched for candidate snake species that would benefit from such armour to protect their body, focusing primarily on fossorial species with defensive tail displays. We examined the tail morphology of 27 snake species from different families using micro-computed tomography (µCT) and micro- radiography. We discovered dermal armour in four species of sand boas (Erycidae) that also feature enlarged and highly modified caudal vertebrae. This is the first description of dermal armour in snakes. Ancestral state reconstructions revealed that osteoderms likely evolved once or multiple times in Erycidae. We have not found osteoderms in any other examined snake species. Nevertheless, similar structures are known from unrelated squamate clades, such as gerrhosaurids and geckos. This supports the idea of underlying deep developmental homology. We propose the hypothesis that osteoderms protect sand boas like the "brigandine armour" of medieval warriors. We interpret it as another component of the sand boas' rich defence strategy.