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PubMedDate not supplied

[The evolution of sleep: birds at the crossroads between mammals and reptiles].

INTRODUCTION: The evolution of sleep is one of the mysteries surrounding the sleep. Since the discovery of the two phases in the mammalian sleep, NREM and REM, the sleep researchers have unsuccessfully tried to understand their origin and the causes of the sleep duality. Looking for an answer to these questions, the sleep of reptiles (the parental group of mammals) and birds (also descending from reptiles) has been studied. As a result, NREM and REM were found in birds but not in reptiles, and the question remains thus unresolved. DEVELOPMENT AND CONCLUSIONS: This review presents a critical analysis of the published sleep studies developed in birds and points to a possible cause of the conflict: considerable doubts can be cast on the existence of the two sleep phases in birds. If birds turn to have only one sleep phase, they would have a very similar sleep to that of reptiles. As a consequence, the two phases, REM and NREM, would be exclusive of mammals, and both would have appeared as a consequence of the evolutionary changes in the development of the brain from reptiles to mammals.

Animals↗
PubMed1976

[Enterobacteria of reptiles (author's transl)].

The aerobic gram-negative faecal flora of 78 reptiles consisting of 46 species (39 lizards of 23 species, 15 tortoises of 9 species, 24 snakes of 14 species) was studied. Salmonella was found to be present in 50% of lizards, in 16% of tortoises and in 16% of snakes. There were all together 15 different serotypes. Edwardsiella tarda was isolated in 20% of tortoises, in 12% of snakes but only in 3% of lizards. Tortoises represent therefore the possible normal habitat of Edwardsiella tarda. We isolated Arizona specially from snakes as was described by many authors. A new serotype (Arizona 26a, 26b:27 - 21 = S. arizonae 61:Z10:Z35) was found in a rattlesnake. There were found also much amounts of Citrobacter (52%), E. coli (50%), Proteus mirabilis (49%), Proteus morganii (18%), Proteus rettgeri (26%), Proteus vulgaris (32%). Klebsiella and Enterobacter seem to prefere the lizards. The overwhelming majority of the studied bacteria were lactose-negative, corresponding to the inability of reptiles producing lactose. The normal habitat of Salmonellae in reptiles and the high phylogenetic age of reptiles allows the hypothesis that salmonellae could have a similar old age as their host animals, because the ecological niche, i.e. the bowel of reptiles, has no changed for some hundred million years.

Animals↗
PubMed1991

Differences in the regulation of acetylcholine release upon D2 dopamine and N-methyl-D-aspartate receptor activation between the striatal complex of reptiles and the neostriatum of rats.

Activation of the N-methyl-D-aspartate (NMDA) receptor increases and that of the D2 dopamine (DA) receptor inhibits the release of acetylcholine (ACh) from mammalian neostriatal tissue. Similar effects have been described in the ventral striatum of the rat, however, in the caudomedial part of the nucleus accumbens, D2 receptor activation does not inhibit the release of ACh. Likewise, the NMDA-induced stimulation of the release of ACh in this part of the striatum is much smaller. In the present study we demonstrated that in the striatal complex or striatum of reptiles D2 receptor activation did not result in an inhibition of the release of ACh, whereas the release of DA could be inhibited to a significant extent. These findings indicate that, although D2 receptors are present in the striatum of reptiles, these receptors do not regulate the release of ACh in this brain structure. We observed in the striatum of reptiles a potassium induced and calcium-dependent release of [3H]D-aspartate indicating a neurotransmitter role for aspartate or glutamate (GLU). However GLU and NMDA have only a marginal effect on the release of ACh in the striatum of the reptiles as compared to the effects in the neostriatum of the rat. It is concluded that with respect to the effects of D2 and NMDA receptor activation on the release of ACh, the striatum of reptiles bears most similarity to the caudomedial part of the nucleus accumbens.

Acetylcholine↗
PubMed2004

Reptile envenomation 20-year mortality as reported by US medical examiners.

OBJECTIVES: Accurate reptile envenomation mortality data for the United States is unavailable. Using data from the National Vital Statistics System (NVSS), deaths from 1979 through 1998 were analyzed. METHODS: Records of deaths from reptile envenomation were selected using matches to code E905.0 of the International Classification of Diseases, Ninth Revision. Data for the US population was taken from the 2000 US census estimates. RESULTS: The National Vital Statistics System identified 97 deaths from venomous reptile bites that occurred during the study period. Texas (n = 17), Florida (n = 14), and Georgia (n = 12) reported the most fatalities (44% of fatalities, 16% of 2000 US population). No deaths were reported from 24 states or the District of Columbia. Of the 97 decedents, 88 (91%) were white and 7 (7%) were black. One male and one female were categorized as "other" race. White males had the highest incidence of death by reptile envenomation, accounting for 76% of all fatalities, while comprising only 41% of the US population. Accounting for 19 of the 97 fatalities, males 25 to 34 years old had the most deaths (19.6% of deaths, but 7.1% of the 2000 US population). CONCLUSIONS: From 1979 through 1998, less than 100 deaths by venomous reptile bite were reported nationwide. White male Southerners appear to be at greatest risk. This finding of a specific high-risk population may require further investigation and public health intervention.

Age Factors↗
PubMed2000

A hypothesis as to the organization of cerebral cortex in the common amniote ancestor of modern reptiles and mammals.

Opinions on the evolutionary origins of mammalian neocortex have divided into two camps: (1) antecedents of the superior neocortex (i.e. occipital, parietal and frontal lobes) and temporal neocortex (i.e. temporal lobe) were present in stem amniotes, and these antecedent regions gave rise to dorsal cortex and dorsal ventricular ridge (DVR), respectively, in living reptiles; (2) the stem amniote antecedent of mammalian superior neocortex gave rise to dorsal cortex in the reptilian lineage, while the stem amniote antecedent of mammal claustrum, endopiriform region and/or basolateral/basomedial amygdala gave rise to DVR in reptiles, with mammalian temporal neocortex being a newly evolved structure with no reptilian homologue. The latter hypothesis has the merit of being more consistent with some current homeobox gene data, but it has the disadvantages of positing that mammalian temporal neocortex arose de novo, and of assuming that the high similarity between DVR and temporal neocortex in the organization of thalamic sensory input and corticostriatal projections and in the topology of sensory areas is coincidental. If one assumes that the antecedent of superior and temporal neocortex in stem amniotes was one continuous field that histologically resembled dorsal cortex in living reptiles, the first hypothesis provides basis for a parsimonious account of the origin of superior and temporal neocortex and their considerable resemblance to dorsal cortex and DVR in reptiles, as well as to Wulst and DVR in birds.

Animals↗
PubMed2004

The ends of a continuum: genetic and temperature-dependent sex determination in reptiles.

Two prevailing paradigms explain the diversity of sex-determining modes in reptiles. Many researchers, particularly those who study reptiles, consider genetic and environmental sex-determining mechanisms to be fundamentally different, and that one can be demonstrated experimentally to the exclusion of the other. Other researchers, principally those who take a broader taxonomic perspective, argue that no clear boundaries exist between them. Indeed, we argue that genetic and environmental sex determination in reptiles should be seen as a continuum of states represented by species whose sex is determined primarily by genotype, species where genetic and environmental mechanisms coexist and interact in lesser or greater measure to bring about sex phenotypes, and species where sex is determined primarily by environment. To do otherwise limits the scope of investigations into the transition between the two and reduces opportunities to use studies of reptiles to advance understanding of vertebrate sex determination generally.

Animals↗
PubMed1976

Descending pathways from the brain stem to the spinal cord in some reptiles. II. Course and site of termination.

The course and termination of the pathways descending from the brain stem to the spinal cord have been studied by tracing the ensuing anterograde fiber degeneration, following appropriate lesions in the reptiles Testudo hermanni, Tupinambis nigropunctatus and Python reticulatus. In these reptiles the presence of interstitiospinal, vestibulospinal and reticulospinal pathways has been demonstrated. A crossed rubrospinal tract has been shown in the turtle and lizard, but could not be demonstrated in the Python. The presence of a tectospinal pathway of any importance could not be shown. However, the tectum mesencephali has been found to project profusely to the brain stem reticular formation. The interstitiospinal tract projects predominantly to the ipsilateral side of the spinal cord. The vestibulospinal projection, arising from the large-celled nucleus vestibularis ventrolateralis, comprises a large uncrossed and a small decussating component. The rubrospinal pathway terminates in a particular area of the spinal gray, i.e., the intermediate zone, whereas the interstitiospainal, reticulospinal and vestibulospinal tracts all terminate in the medial part of the ventral horn. It appeared that the classification of descending pathways as advocated in mammals by Kuypers ('64) into lateral and medial systems can be readily applied to reptiles. The lateral system terminates in the dorsal and lateral parts of the intermediate zone, the medial system predominantely in the dorsomedial part of the ventral horn. This classification renders it likely that the absence of a lateral focus of termination as well as the absence of a rubrospinal tract in the Python, is correlated to the absence of limbs. A comparison of experimental data concerning the systems descending from the brain stem to the spinal cord in amphibians, reptiles, birds and mammals suggests that these systems with regard to origin, course and termination have a basic pattern in common.

Animals↗
PubMed2003

Adaptation to the land: The skin of reptiles in comparison to that of amphibians and endotherm amniotes.

The adaptation to land from amphibians to amniotes was accompanied by drastic changes of the integument, some of which might be reconstructed by studying the formation of the stratum corneum during embryogenesis. As the first amniotes were reptiles, the present review focuses on past and recent information on the evolution of reptilian epidermis and the stratum corneum. We aim to generalize the discussion on the evolution of the skin in amniotes. Corneous cell envelopes were absent in fish, and first appeared in adult amphibian epidermis. Stem reptiles evolved a multilayered stratum corneum based on a programmed cell death, intensified the production of matrix proteins (e.g., HRPs), corneous cell envelope proteins (e.g., loricrine-like, sciellin-like, and transglutaminase), and complex lipids to limit water loss. Other proteins were later produced in association to the soft or hairy epidermis in therapsids (e.g., involucrin, profilaggrin-filaggrin, trichohyalin, trichocytic keratins), or to the hard keratin of hairs, quills, horns, claws (e.g., tyrosine-rich, glycine-rich, sulphur-rich matrix proteins). In sauropsids special proteins associated to hard keratinization in scales (e.g., scale beta-keratins, cytokeratin associated proteins) or feathers (feather beta-keratins and HRPs) were originated. The temporal deposition of beta-keratin in lepidosaurian reptiles originated a vertical stratified epidermis and an intraepidermal shedding layer. The evolutions of the horny layer in Therapsids (mammals) and Saurospids (reptiles and birds) are discussed. The study of the molecules involved in the dermo-epidermal interactions in reptilian skin and the molecular biology of epidermal proteins are among the most urgent future areas of research in the biology of reptilian skin.

Adaptation, Biological↗
PubMed2001

Temperature-dependent sex determination and gonadal differentiation in reptiles.

In many reptile species, sexual differentiation of gonads is sensitive to temperature (temperature-dependent sex determination, TSD) during a critical period of embryonic development (thermosensitive period, TSP). Experiments carried out with different models including turtles, crocodilians and lizards have demonstrated the implication of estrogens and the key role played by aromatase (the enzyme complex that converts androgens to estrogens) in ovary differentiation during TSP and in maintenance of the ovarian structure after TSP. In some of these experiments, the occurrence of various degrees of gonadal intersexuality is related to weak differences in aromatase activity, suggesting subtle regulations of the aromatase gene at the transcription level. Temperature could intervene in these regulations. Studies presently under way deal with cloning (cDNAs) and expression (mRNAs) of genes that have been shown, or are expected, to be involved in gonadal formation and/or differentiation in mammals. Preliminary results show that homologues of the WT1, SF1, SOX9, DAX1 and AMH genes exist in TSD reptiles. However, the expression patterns of these genes during gonadal differentiation may be different between mammals and TSD reptiles and also between different reptile species. How these genes could interact with aromatase is being examined.

Animals↗
PubMed2005

Characterization of MHC class II genes from an ancient reptile lineage, Sphenodon (tuatara).

The organization and evolution of major histocompatibility complex (MHC) genes vary considerably among vertebrate lineages. MHC genes have been well characterized in mammals, birds, amphibians and fish, but little is known about their organization in reptiles, despite the fact that reptiles occupy an important phylogenetic position for understanding the evolutionary history of both mammalian and avian MHC genes. Here we describe the characterization of the first MHC class II B cDNA sequences from a non-avian reptile, the tuatara (Sphenodon spp.). Three class II B sequences were isolated from a tuatara cDNA library, and four additional partial sequences were isolated by reverse transcriptase-polymerase chain reaction. Six of these sequences appear to belong to the same gene family, which we have named SppuDAB. The remaining sequence (named SppuDBB) shares only 43.9% amino acid similarity with SppuDAB and thus appears to represent a separate gene family. SppuDBB may be a non-classical locus as it does not contain all the conserved residues expected of a classical MHC class II gene. Southern blot analysis indicates that only a single copy of SppuDBB exists in tuatara, but that multiple loci related to SppuDAB are present. The SppuDAB sequences have the highest amino acid similarity (57.2-62.4%) with class II B sequences from the spectacled caiman, but only 26.4-48.7% similarity with sequences from other vertebrates. The tuatara sequences do not strongly group with other reptile sequences on a phylogenetic tree, reflecting the antiquity of the Sphenodon lineage and the lack of closely related sequences for comparison.

Amino Acid Sequence↗
PubMed2006

Importation of exotic ticks into the United Kingdom via the international trade in reptiles.

Due to the increased trade in exotic reptiles, many of which are infested with ticks of various genera, there is an increased risk of exotic ticks and pathogens being introduced and potentially becoming established in new geographical areas. Despite the number and variety of tick species collected from reptiles, their role in the maintenance of pathogens and transmission to humans has not been fully investigated for all species. The potential public health risks to the United Kingdom have been examined through a preliminary study involving the collection and identification of exotic tick species imported via the reptile trade. Reptiles imported into Heathrow Airport, London (July 2003-October 2004) were carefully examined for ectoparasites. Five species of tick were collected: Aponomma exornatum, Ap. latum, Amblyomma rotundatum, Am. dissimile and Am. nuttalli. This is the first report of Am. dissimile identified from an interception at Heathrow airport. The potential for establishment of exotic ticks in the UK and the public health risks are discussed.

Animals↗
PubMed2005

Equipping the reptile practice.

Reptile medicine and surgery has advanced so much in the last 15 years, and clients are becoming increasingly aware of the needs of their reptile pets. As such, it is important for veterinary practitioners to advance their education in reptile medicine if they intend to add reptiles as patients to their clinics. Equally important is to realize one's limitations and to not only know when it is time to refer but to find out which practices near them are the best prepared for referral of these unique pets.

Animals↗
PubMed2003

Reptile respiratory medicine.

Respiratory tract disease is commonly diagnosed in captive collections of reptiles and associated with high morbidity and mortality. Improper environmental conditions are often contributing factors for the development of respiratory disease in reptiles. A detailed knowledge of the unique reptilian respiratory morphology and function is essential to successfully diagnose and treat respiratory disease. A variety of noninfectious and infectious causes have been identified in the etiology of reptile respiratory disease. Knowledge of the pathophysiology of reptilian diseases is increasing, and with the availability of new therapeutic agents and advanced diagnostic techniques, the diagnosis and treatment of reptile respiratory tract disease has become more successful.

Animals↗
PubMed2002

Framework for assessment and monitoring of amphibians and reptiles in the Lower Urubamba region, Peru.

Populations of amphibians and reptiles are experiencing new or increasing threats to their survival. Many of these threats are directly attributable to human activity and resource development. This presents the increasing need for worldwide amphibian and reptile assessments and effective, standardized monitoring protocols. Adaptive management techniques can assist managers in identifying and mitigating threats to amphibian and reptile populations. In 1996, Shell Prospecting and Development, Peru initiated a natural gas exploration project in the rainforest of southeastern Peru. The Smithsonian Institution's Monitoring and Assessment of Biodiversity Program worked closely with Shell engineers and managers to establish an adaptive management program to protect the region's biodiversity. In this manuscript, we discuss the steps we took to establish an adaptive management program for amphibian and reptile communities in the region. We define and outline the conceptual issues involved in establishing an assessment and monitoring program, including setting objectives, evaluating the results and making appropriate decisions. We also provide results from the assessment and discuss the appropriateness and effectiveness of protocols and criteria used for selecting species to monitor.

Amphibians↗
PubMed2001

Assessment of the husbandry problems of reptiles on the basis of pathophysiological findings: a review.

Many health problems in animals are related to management and feeding. A large number of husbandry problems in reptiles lead to pathophysiological situations. Assessment of the husbandry problems of reptiles involves detective work that can only be achieved as a result of close cooperation and exchange of information between the owner and the pathologist. Reptiles, being ectothermic, depend for their physiological functioning largely on the quality of their surroundings. There are a large number of factors which influence the normal functioning of a reptile both in nature and in captivity. These factors can be described in terms of primary and secondary factors. Primary factors are the construction of terraria, light, heat, food, and water, and grouping of animals. Secondary factors are daylight regimen, arrangement of heating elements, type and composition of food, quality of water, and freedom from stress. Also important are ventilation, humidity, sites for resting and/or hiding, structure of the floor and of rocks, and branches for climbing activities. Hygiene is also an important aspect because poor hygiene often is directly related to problems. All these factors are dealt with in this review.

Animal Diseases↗
PubMed2006

Influence of incubation temperature on hatchling phenotype in reptiles.

Incubation temperature influences hatchling phenotypes such as sex, size, shape, color, behavior, and locomotor performance in many reptiles, and there is growing concern that global warming might adversely affect reptile populations by altering frequencies of hatchling phenotypes. Here I overview a recent theoretical model used to predict hatchling sex of reptiles with temperature-dependent sex determination. This model predicts that sex ratios will be fairly robust to moderate global warming as long as eggs experience substantial daily cyclic fluctuations in incubation temperatures so that embryos are exposed to temperatures that inhibit embryonic development for part of the day. I also review studies that examine the influence of incubation temperature on posthatch locomotion performance and growth because these are the traits that are likely to have the greatest effect on hatchling fitness. The majority of these studies used artificial constant-temperature incubation, but some have addressed fluctuating incubation temperature regimes. Although the number of studies is small, it appears that fluctuating temperatures may enhance hatchling locomotor performance. This finding should not be surprising, given that the majority of natural reptile nests are relatively shallow and therefore experience daily fluctuations in incubation temperature.

Animals↗
PubMed2025

Global Environmental Factors Impact the Evolution of Adult Hemoglobins in Squamata Reptiles (Lizards and Snakes) and Terrestrial Turtles.

Convergent evolution of oxygen transport mechanisms arises from respiratory proteins adapting to similar environmental pressures. We examined this relationship between adult hemoglobin subunits (Hbs: HBA1, HBAD, HBB1, and HBB2) found in land reptiles (lizards, snakes, and turtles) with their global distribution variables: Altitude, latitude, ambient temperature, and biomass production. We found that biomass was positively associated with the synonymous substitution rate (dS) of HBAD, while it showed the opposite trend for HBB2 in snakes. Additionally, latitude was negatively related to the dS of HBB2 in snakes, but nonsignificant with other Hbs. Altitude was negatively associated with ω = dN/dS of HBA1 and HBAD, whereas temperature showed a similar negative trend with the ω of HBAD across reptiles and in HBB2 of snakes. At amino acid sites, we found most were conserved except for 11 (two near the heme-binding pocket) across Hbs. These fast-changing sites shifted from polar to nonpolar residues, showing a pattern seen in high-altitude mammals. Our results highlight that in reptiles (i) Hbs are diversifying at individual amino acid sites while generally some subunits exhibiting lower ω rates at higher altitudes and hotter temperatures, with the later and higher biomass ecosystems also linked to increases in dS; (ii) HBBs are the most conserved of the Hbs; (iii) latitudinal gradients only show a significant association with the dS of HBB2 in snakes; and (iv) gene conversion events occurred across HBBs in reptiles, which confound their homology assignation, except for snakes that evidenced a single major duplication in their HBBs.

Animals↗
PubMed2006

Alerting pregnant women to the risk of reptile-associated salmonellosis.

BACKGROUND: Reptile- and amphibian-associated salmonellosis poses significant risk to infants and young children. The Centers for Disease Control and Prevention has advised that reptiles and amphibians should not be kept in households with children younger than 5 years old. CASE: We report a 5-day-old newborn with Salmonella bacteremia and meningitis who survived but with severe developmental delay. CONCLUSION: Cases of infants with reptile- and amphibian-associated salmonellosis, a preventable and devastating disease, continue to be reported. We propose that obstetricians should be the front line in counseling expecting families that reptiles should not be kept in households with infants and young children. By the time a family first visits the pediatrician, the warning may be too late.

Animals↗