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At least 19 recordsLinked to original sources

PubMed1977

Body temperature and tumor virus infection. I. Tumorogenicity of Rous sarcoma virus for reptiles.

Rous sarcoma virus (RSV) was oncogenic for the following nine species of reptiles representing 6 families from Chelonia and Squamata orders: family of Testudinidae: 1. Testudo horsfieldi, family Agamidae: 2. Agama sanguinolenta; 3. Agama erythrogastra, family Lacertidae: 4. Eremias persica; 5. Eremias velox; 6. Eremias grammica, family Scincidae: 7. Eumeces taeniolatus, family Boidea: 8. Erix tataricus, 9. Ancistrodom blomhoffi. RSV did not induce tumors in 13 studied species of reptiles. Histologically 26 reptile tumors studied were polymorphous sarcomas with spindle-shaped (fibroblast-like), round and polygonal macrophage-like cells and sometimes peculiar giant polynuclear cells. Chromosomal analysis showed that reptile tumors arose out of reptile cells. RSV was pathogenic for adult reptiles. Reptile tumors did not contain a mature infectious virus. The tumors of 2 snakes were virogenic. The effect of increased temperature at the body level on the transformation of a symptomless viral infection into a viral disease is discussed in the evolutionary aspect.

Animals↗

PubMed1991

Environmental sex determination in reptiles: ecology, evolution, and experimental design.

Sex-determining mechanisms in reptiles can be divided into two convenient classifications: genotypic (GSD) and environmental (ESD). While a number of types of GSD have been identified in a wide variety of reptilian taxa, the expression of ESD in the form of temperature-dependent sex determination (TSD) in three of the five major reptilian lineages has drawn considerable attention to this area of research. Increasing interest in sex-determining mechanisms in reptiles has resulted in many data, but much of this information is scattered throughout the literature and consequently difficult to interpret. It is known, however, that distinct sex chromosomes are absent in the tuatara and crocodilians, rare in amphisbaenians (worm lizards) and turtles, and common in lizards and snakes (but less than 20% of all species of living reptiles have been karyotyped). With less than 2 percent of all reptilian species examined, TSD apparently is absent in the tuatara, amphisbaenians and snakes; rare in lizards, frequent in turtles, and ubiquitous in crocodilians. Despite considerable inter- and intraspecific variation in the threshold temperature (temperature producing a 1:1 sex ratio) of gonadal sex determination, this variation cannot confidently be assigned a genetic basis owing to uncontrolled environmental factors or to differences in experimental protocol among studies. Laboratory studies have identified the critical period of development during which gonadal sex determination occurs for at least a dozen species. There are striking similarities in this period among the major taxa with TSD. Examination of TSD in the field indicates that sex ratios of hatchlings are affected by location of the nests, because some nests produce both sexes whereas the majority produce only one sex. Still, more information is needed on how TSD operates under natural conditions in order to fully understand its ecological and conservation implications. TSD may be the ancestral sex-determining condition in reptiles, but this result remains tentative. Physiological investigations of TSD have clarified the roles of steroid hormones, various enzymes, and H-Y antigen in sexual differentiation, whereas molecular studies have identified several plausible candidates for sex-determining genes in species with TSD. This area of research promises to elucidate the mechanism of TSD in reptiles and will have obvious implications for understanding the basis of sex determination in other vertebrates. Experimental and comparative investigations of the potential adaptive significance of TSD appear equally promising, although much work remains to be performed. The distribution of TSD within and among the major reptilian lineages may be related to the life span of individuals of a species and to the biogeography of these species.(ABSTRACT TRUNCATED AT 400 WORDS)

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↗

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↗

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↗

PubMed2026

Modeling reptile virus infection in vitro using Python regius airway organoids.

Zoonoses pose substantial global health risks, highlighting the need to better understand animal-to-human transmission. Reptiles are increasingly recognized as hosts of diverse pathogens, including numerous viruses, yet the diversity and prevalence of reptile pathogens, as well as their potential risk to humans, remain poorly understood. Here, we establish and characterize airway organoids derived from Python regius, providing an in vitro model to study reptile airway infection. Through de novo assembly of a Python regius reference genome, we characterize airway organoids at single-cell resolution, which suggests the presence of diverse cell populations including ionocytes, ciliated, secretory, goblet, endocrine, tuft, and basal cells. The organoids support productive infection with Ball Python Nidovirus (BPNV) and mount a robust epithelial antiviral response through the induction of interferon-stimulated genes, cytokines, and genes involved in chemical defense. As a proof-of-concept, treating organoids with antiviral drugs during infection reduces BPNV levels, highlighting the model's utility for drug testing. By providing a reductionist system of the serpentes airway, these organoids constitute a physiologically relevant in vitro model to study reptile viruses and host-pathogen interactions in their native host.

Animals↗

PubMed1991

Electrocorticograms of hippocampal and dorsal cortex of two reptiles: comparison with possible mammalian homologs.

To compare the ongoing electrical activity in possibly homologous structures of reptiles and mammals, the electrographic activity (micro-EEG) from major parts of the cortex of unanesthetized turtles (Pseudemys) and geckos (Gekko) was recorded with and without acute and chronic stimuli, physostigmine and atropine. Electrodes were placed in the medial cortex (MC) and in the dorsal cortex (DC), the possible homologs of the mammalian hippocampus and transitional or/and isocortex, respectively. The resting corticograms (1-50 Hz) are different in the two cortical areas. Both are wide-band; power falls steadily with frequency above a single maximum about 2 Hz. The MC has a nonrhythmic, low-voltage activity with occasional superimposed large sharp waves (LSWs), generally biphasic, 100-300 microV and lasting 0.25-0.75 s. The DC has smaller amplitudes (ca. 3-6 dB) at all frequencies and fewer LSWs. Reptilian LSWs are reminiscent of mammalian hippocampal sharp waves or spikes, a correlate of decreased arousal. The immobility-related rhythmic slow activity (theta), so characteristic of the hippocampus in a number of mammals, was not found in the cortex of either species of reptile under a variety of conditions. We cannot exclude the possibility of movement-related theta waves. Physostigmine injection does not produce theta, although it acts like an arousing stimulus, producing a disappearance of the LSWs and a substantial increase in the amplitude of the frequencies 12-24 Hz; these changes were more obvious in the DC. Atropine reversed the effects of physostigmine. Theta may represent a trait of the more highly differentiated hippocampal field of mammals. The condition represented by these reptiles, in which the EEG differs between parts of the pallium but without theta or reciprocal changes in the MC and DC, may be an earlier evolutionary stage. A distinctive reptilian EEG is not recognizable in Pseudemys and Gekko, but a number of differences from the EEG in familiar mammals are shared by these two neurologically quite different reptiles.

Animals↗

PubMed1976

Descending pathways from the brain stem to the spinal cord in some reptiles. I. Origin.

In the present study of the origin of the pathways descending from the brain stem to the spinal cord has been investigated in the reptiles Testudo hermanni, Pseudemys scripta elegans, Tupinambis nigropunctatus and Python reticulatus. These reptiles, using highly different types of progression, have been selected, because fundamental variations in the organization of the central motor apparatus are to be expected. The origin of the descending pathways has been demonstrated by recording the occurrence of retrograde cell changes following hemicordotomies and by searching for labeled cells following injection into the spinal cord of the enzyme horseradish peroxidase. In the reptiles studies the presence of interstitiospinal, vestibulospinal and reticulospinal pathways could be demonstrated. A crossed rubrospinal tract has been shown in the turtles and in the lizard, but could not be demonstrated in the Python. The presence of a direct tectospinal pathway could not be shown.

Animals↗

PubMed1991

Comparative aspects of the basal ganglia-tectal pathways in reptiles.

To determine how the basal ganglia in reptiles may influence visuomotor behavior, the connections from the basal ganglia to the tectum of the midbrain were studied in several species of reptiles. Immunohistochemical studies by means of antibodies against Leu-enkephalin (LENK) as well as experimental hodological studies with anterograde (PHA-L) and retrograde (HRP, Fluorogold, Cholera toxin) tracers were carried out. The results indicate that within the class of Reptilia, two different patterns occur: one in which information from the basal ganglia is relayed to the tectum via the substantia nigra as well as via a pretectal, enkephalinergic cell group, and another one in which only the ventral route, via the substantia nigra, is present. The former pattern is found in turtles, crocodiles, and the lacertid lizards Podarcis and Gallotia, and the latter pattern in the gekkonid lizards Gekko and Eublepharis, in Varanus, and in the snakes Python and Thamnophis. The presence or absence of the pretectal relay center is reflected in the laminar distribution of LENK immunoreactivity in the tectum. The apparent lack of a pretectal relay in nocturnal gekkonids and in snakes underlines the hypothesis (Reiner et al., '84: T.I.N.S. 7:320-325) that a de-emphasis of visual-basal ganglia mechanisms has occurred during the evolution of ancestral reptiles to modern mammals.

Animals↗

PubMed1992

Experimental transmission of Cowdria ruminantium (Rickettsiales) by the American reptile tick Amblyomma dissimile Koch, 1844.

A Senegalese isolate of the rickettsia Cowdria ruminantium was transmitted transstadially by nymphs of the American reptile tick Amblyomma dissimile. Only eight nymphs, fed as larvae on a Saanen goat reacting to heartwater, were required to transmit fatal heartwater to another susceptible goat. Since A. dissimile usually feeds on snakes, iguanas and lizards in central America, the tick is not considered to play a significant role in the transmission of heartwater between ruminants. However, the tick could play a role in maintaining a rickettsial reservoir in reptile populations, since it has been shown that an African reptile can be a subclinical carrier of C. ruminantium, infective to vector ticks.

Animals↗

PubMed1991

[The use of diagnostic imaging methods in reptiles].

Useful methods of clinical imaging in reptiles are described using examples. Most important in reptiles is radiography with or without contrast media. Invasive diagnostic methods often used are endoscopy and laparoscopy. Ultra sound scanning in reptiles is established for controlling ovary function.

Animals↗

PubMed1976

[Morphology of the endocrine portion of the reptile pancreas].

The endocrinous part of the pancreatic gland of reptiles Lacerta agilis, Agama sanguinolenta, Varanus griseus, Testudo horsfieldi and Clemmus Caspica is formed by A-, B- and D-cells. The main form of its structural organization is pancreatic islands. In adition to them, remnants of the "external epithelium" are found in Varanus griseus and A-cells disposed outside of the pancreatic islands in Testudo horsfieldi and Clemmys caspica. As compared with amphibia, reptiles have a better developed counterinsular component (A-cells) of the endocrinous part of the pancreas. The acino-island cells of "A" and "D" types are also found in the pancreas of reptiles, "A"-type cells being predominant among them.

Animals↗

PubMed1991

Inositol phosphate formation in uterine tissue from two species of reptiles is stimulated by arginine vasotocin and influenced by stage of reproduction.

Phosphoinositide hydrolysis, resulting in inositol trisphosphate (IP3) and diacylglycerol (DG) formation, has been implicated in oxytocin-stimulated pulsatile secretion of prostaglandin F2 alpha (PGF2 alpha) from uterine endometrium of sheep and other mammals. In reptiles, arginine vasotocin (AVT) stimulates uterine secretion of PGF2 alpha. These studies investigated the ability of AVT to stimulate incorporation of [3H]inositol into inositol mono-, bis-, and trisphosphates in two reptilian species. In Experiment 1, AVT stimulated (P less than 0.01) IP formation in uterine from late-gravid (150 to 291%) and postpartum (104 to 363%) Yarrow's spiny lizards (Sceloporus jarrovi). Inositol phosphate formation, in response to AVT, was greater (P less than 0.01 for IP3 and P less than 0.05 for total IP) for gravid (stage 40 embryos) and postpartum (1-2 days) lizards near the time of parturition than for lizards at other stages (stage 38-39 embryos or 7 days postpartum). Inositol phosphate formation was greater (P less than 0.05) in uterine tissue from gravid than from postpartum lizards. In Experiment 2, basal IP formation and the response to AVT were the greatest (P less than 0.01) in endometrium from late-gravid American alligators (Alligator mississippiensis). AVT stimulated (P less than 0.02) IP synthesis in uterine endometrium from vitellogenic (136 to 394%), early-gravid (7 to 270%), late-gravid (315 to 1002%), postpartum (86 to 313%), and nonreproductive (292 to 322%) alligators. Results indicate that (1) AVT stimulates IP formation in the uterus of reptiles; (2) uterine IP formation increases in late-gravid reptiles; and (3) increased responsiveness to AVT may occur at parturition or oviposition.

Animals↗

PubMed1977

Physiological actions of human follicle-stimulating hormone and its beta-subunit in reptiles.

The actions of human follicle-stimulating hormone (hFSH) and its beta-subunit were examined in several assays in reptiles, including effects on lizard testicular activity (growth and androgen production) in vivo, and stimulation of androgen production by snake testes and competition for binding of 125I-labeled hFSH in lizards and snakes in vitro. Binding was also examined with mammalian tissues. The hFSH was highly steroidogenic in the snake and lizard; otherwise results were similar to those observed in mammals. In all cases, the potency of the beta-subunit was only a few per cent of the intact hormone. The potency of hFSH in vivo compared with NIH-FSH ovine standards was several 100 times greater than in vitro. Results for stimulation of androgen production in vivo closely paralleled those for binding assays in both reptiles and mammals. In contrast to previous results for ovine FSH beta-subunit, human FSH beta-subunit has little if any FSH biological activity in reptiles.

Androgens↗

PubMed1977

Nature and rate of neoplasia found in captive wild mammals, birds, and reptiles at necropsy.

The nature and rate of neoplasia found at necropsy of captive wild animals of the Zoological Society of San Diego collection were studied. Neoplasia was present at necropsy in 2.75% of 3,127 mammals, 1.89% of 5,957 birds, and 2.19% of 1,233 reptiles. Neoplasms were not detected during 198 necropsies of amphibians. Gross and histologic examinations were performed on the 92 mammalian, 111 avian, and 28 reptilian neoplasms. The lesions were diagnosed. The findings findings included a high frequency of lymphosarcomas in birds and reptiles, multiple lung adenomas in mammals, multiple endocrine tumors in 2 European mouflons (Ovis musimon), and proliferative lesions of the biliary and pancreatic ductal systems in several species.

Animals↗

PubMed1979

Reptiles and mammals use similar sensory organizations in the midbrain.

Striking similarities were observed between the overlapping visual and tactile maps of the mammalian superior colliculus and of its homolog in reptiles, the optic tectum. This topographic pattern probably represents a plan of sensory representation that existed in ancient reptiles and that was retained during the evolution to mammalian forms more than 180 million years ago.

Animals↗

PubMed1992

[Reptiles as patients in veterinary practice].

Important diseases of reptiles are described with references to the diagnostic material and patients of the Institute of Zoology and Hydrobiology between 1984 and 1990. The commonest causes of mortality were pneumonia, parasites and poor husbandry. Problems associated with the increasing popularity of reptiles as pets, and appropriate treatments are discussed.

Animal Husbandry↗