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At least 19 recordsLinked to original sources

The brain of the mammal-like reptile Probainognathus jenseni (Therapsida, Cynodontia). A correlative paleo-neoneurological approach to the neocortex at the reptile-mammal transition.

A natural endocranial cast of the South American cynodont Probainognathus jenseni is studied, and an evaluation of the probable nature of the neocortex at the level of certain cynodonts of the Middle Triassic is made, based in the available paleo-neoneurological information. The endocast of Probainognathus shows well developed olfactory bulbs, long cerebral hemispheres, small anterior colliculi and well represented cerebellum and flooculi. The pineal gland may have been located between the caudal hemispheric poles. No parietal foramen exists. The dorsal surface of the cerebral hemispheres shows a slope at the level of the anterior edge of the caudal fourth part, which is interpreted as the posterior limit of the neocortical plate. At the level of the olfactory peduncles, it is visible a stem vessel; one of its branches distributes on the anterior part of the lateral border of the hemisphere. It is advanced the interpretation that this latter vessel could indicate the paleo-neocortical boundary. The analysis of the neoneurological information led the author to suppose that the neocortex of Probainognathus, and surely of other cynodonts of the Middle Triassic, has shown supplementary somatic sensory and motor, visual and auditory representations, and perhaps incipient primary somati sensory and motor ones, advancing a "polymodal cortex", as it is supposed had stem mammals. Moreover, the histostructure of the neocortex at this state of the evolution may have been in a proisocortical-isocortical stage, that is, in the beginnings of the true neocortex. The confrontation of the paleoneurologic with the neoneurologic information led the author to suppose that Triconodon and Ptilodus have had a neocortex, surely more developed than Probainognathus, but that it is not seen in the endocasts at present studied. The quantitative analysis of Probainognathus' endocast, as well as those of other cynodonts, suggest that certain cynodonts of the Middle Triassic were in an advanced state toward endothermy.

Animals↗

Oxygen storage capacity and tolerance of submergence of a non-aquatic reptile and an aquatic reptile.

The oxygen storage capacities and the tolerance to submergence of an aquatic snake, Natrix sipedon, and a non-aquatic snake, Crotalus viridis, were determined and compared. C. viridis was found to have a larger oxygen storage capacity, hemoglobin content and blood volume than N. Sipedon. The submergence time for C. viridis was 30.13 min which was less than the estimated time for submergence based on the oxygen storage capacity. N. sipedon exceeded its estimated dive time of 24.00 min and remained submerged for 65.57 min without signs of stress. During submergence, the heart rate of N. sipedon fell to 9% (5 beats/min) of the resting rate, while the heart rate of C. viridis fell to only 75% (27 beats/min) of the resting rate during this activity. These data indicate that N. sipedon responds to submergence via a typical diving reflex and extends its oxygen stores beyond that expected of a non-diver such as C. viridis.

Animals↗

Further characterization of the major forms of reptile beta-endorphin.

Biosynthetically labeled reptile intermediate pituitary beta-endorphin-sized material was fractionated by SP-Sephadex ion exchange chromatography into two major opiate-active forms which eluted at 0.28 M NaCl and 0.32 M NaCl, respectively; the 0.32 M form of reptile beta-endorphin (mw = 3500), serves as the precursor for the 0.28 M form of reptile beta-endorphin (mw = 3200), (Dores and Surprenant, 1983). Analysis of tryptic digests of these reptile beta-endorphins by paper electrophoresis at pH 3.5 and gel filtration on a Sephadex G-15 column indicated that there are two tyrosine residues, two arginine residues and one methionine residue in reptile beta-endorphin. Furthermore, the NH2-terminal tryptic peptide of both reptile beta-endorphins is approximately nine amino acids in size and contains tyrosine, methionine and arginine. Analyses of chymotryptic/protease digests of the [3H]tyrosine-labeled NH2-terminal tryptic peptide analyzed by descending paper chromatography revealed that the NH2-terminal tyrosine of reptile beta-endorphin is not alpha-N-acetylated. A second tyrosine-containing tryptic peptide was detected in the COOH-terminal region of reptile beta-endorphin; however this tryptic peptide differs in the two forms of reptile beta-endorphin in terms of size and net charge at pH 3.5. These differences account for the apparent molecular weight differences and distinct ion exchange properties of the 0.28 M and 0.32 M forms of reptile beta-endorphin. Thus in the reptile intermediate pituitary the principal post-translational mechanism for modifying beta-endorphin is COOH-terminal proteolytic cleavage.

Animals↗

Salmonella enterica in reptiles of German and Austrian origin.

Captive reptiles are routinely identified as reservoirs of Salmonella spp. and the number of reports about reptile-associated salmonellosis is increasing. In the present study, Salmonella were detected in 86 of 159 (54.1%) faecal reptile samples cultured. The percentage of Salmonella positive samples was significantly lower in turtles as compared with lizards and snakes, as Salmonella were only detected in one sample from a single turtle out of 38 turtles investigated. In all, 42 different Salmonella serovars were found. All isolated Salmonella belonged to the species enterica, predominantly to the subspecies I (n=46) and IIIb (n=30), but also to subspecies II (n=3), IIIa (n=6) and IV (n=2). All isolates were sensitive to the antimicrobials examined. A comparison between the reptile owners indicated that either no Salmonella were found, or that Salmonella could be isolated from all or nearly all animals of the respective owners. A significantly higher percentage of Salmonella positive reptiles was detected in the group of owners who purchase reptiles in comparison with pure breeders. A total of 88.9% of Salmonella isolates were found in samples of reptiles bought in pet shops and 58.8% in samples from wild-caught animals. The high percentage of Salmonella in reptiles in our study confirms the risk for the transmission of the infection to humans.

Animals↗

Reptiles as models of contaminant-induced endocrine disruption.

Historically, reptiles have been used as bioindicators of environmental contaminants and, currently, reptiles have the potential to elucidate the mechanisms of a newly described group of environmental contaminants--endocrine disrupters. Reptiles are particularly good models for studying endocrine altering compounds due to the fact that different species of reptiles have varying modes of gender determination (genotypic sex determination or temperature-dependent sex determination) and parity modes (oviparity or viviparity). This review focuses both on laboratory and field studies of contaminant-induced endocrine alterations in reptiles. Laboratory studies of oviparous reptiles with temperature-dependent sex determination reveal that embryonic exposure to natural hormones and many man-made chemicals (including the ubiquitous PCBs and common herbicides) can permanently alter the functioning of the reproductive system. It is hypothesized that similar permanent, organizational changes occur in wild reptiles exposed to endocrine-disrupting contaminants.

Animals↗

Reptile-associated salmonellosis in New York State.

To determine the association between reptile ownership and salmonellosis caused by certain rare serotypes of Salmonella, we reviewed 1993 New York State Salmonella case reports and conducted a matched case-control study. Cases were persons identified from 1993 New York State laboratory records who had salmonellosis caused by Salmonella serotypes commonly isolated from reptiles. Controls were selected from 1993 New York State shigellosis cases and matched for age and date of diagnosis. Of 674 Salmonella case reports 27 (4%) noted reptile exposure before onset of illness. For the case-control study we identified 42 persons with selected Salmonella serotypes, of whom we contacted 24 (57%). Twelve of 24 case patients and 2 of 28 controls owned reptiles (matched odds ratio, 6.6; 95% confidence interval, 1.4 to 31.0). Ten case-patients but no controls owned iguanas (MOR = undefined; 95% confidence interval, 2.24-infinity). Ten of 12 case patients who owned reptiles were < or = 6 months of age. Salmonellosis caused by certain serotypes is associated with reptile exposure. Reptiles may be unfit pets for homes with infants.

Adolescent↗

In vitro inhibition of Salmonella organisms isolated from reptiles by an inactivated culture of microcin-producing Escherichia coli.

OBJECTIVE: To determine whether an inactivated culture of a microcin-producing avian Escherichia coli was capable of killing Salmonella isolates from reptiles in an in vitro test system. SAMPLE POPULATION: 57 Salmonella isolate from reptiles. PROCEDURE: A wild-type avian E. coli electrotransformed with a plasmid coding for the production of microcin 24 was tested in an in vitro microassay system for its ability to kill 57 Salmonella spp isolated from reptiles. The reptile population included snakes, iguana, frilled lizards, turtles, other lizards, and unspecified reptiles. RESULTS: 44 of the Salmonella isolates were inhibited strongly, compared with the in vitro assay controls; 12 had weak inhibition, and 1 was not inhibited by the microcin-producing E. coli. Thirteen of the 57 isolates had resistance to at least 1 antibiotic, primarily streptomycin. There were 9 O serogroups identified in the 57 isolates, with serogroup H being the most prevalent (18 to 57). CONCLUSION AND CLINICAL RELEVANCE: Antibiotics are not recommended to eliminate Salmonella organisms from reptiles because of the development of antibiotic resistance. Further studies are necessary to determine whether the use of microcin-producing bacteria will be effective in controlling Salmonella infections in companion reptiles.

Animals↗

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↗

Basal ganglionic pathways to the tectum: studies in reptiles.

Relations between the basal ganglia and the tectum were investigated in two different orders of reptiles: turtles (Chrysemys scripta) and crocodilians (Caiman crocodilus). In both species, efferents from the paleostriatal complex, a telencephalic region considered comparable to the mammalian basal ganglia on the basis of topographic, histochemical, and hodological criteria, were found to project to a prominent pretectal cell group called the dorsal nucleus of the posterior commissure (nDCP). Cells within nDCP, in turn, were found to project extensively upon the optic tectum. This paleostriatal-pretectal-tectal pathway is comparable to a previously described paleostriatal-pretectal-tectal channel in birds that involves a relay in the pretectal nucleus, spiriformis lateralis (SpL). Neither the presently described paleostriatal-pretectal-tectal channel of reptiles nor that previously described in birds, however, appears comparable to the superficially similar basal ganglionic-nigral-superior collicular pathway of mammals. Rather, data from the present experiments indicate the existence of a second paleostriatal channel to the tectum, one which does appear comparable to the basal ganglionic-nigral-superior collicular pathway of mammals. This second paleostriatal channel to the tectum, relayed via a tegmental cell group termed the substantia nigra in turtles and the tegmentipedunculopontine complex in caiman, is of much lesser prominence in reptiles than the paleostriatal-pretectal-tectal channel. The present results indicate the existence of at least two separate systems by which the basal ganglia in reptiles can influence the midbrain roof. These two channels, particularly the prominent paleostriatal-pretectal-tectal pathway, may represent major routes by which the basal ganglia influence motor functions in reptiles. Further, although previous research had only indicated the existence of a paleostriatal-pretectal-tectal pathway in birds and a basal ganglionic-nigral-collicular channel in mammals, existing data are consistent with the hypothesis that both presently described pathways in reptiles exist in birds and mammals, though only one of the two may be prominent in mammals.

Alligators and Crocodiles↗

The thalamus of reptiles and mammals: similarities and differences.

Certain aspects of thalamic organization in reptiles and mammals are reviewed. Features shared by the dorsal thalamus of reptiles and that of mammals include projection to the telencephalon, specific and non-specific non-telencephalic afferents, and input from the thalamic reticular nucleus. Differences between the dorsal thalamus of reptiles and that of mammals are the absence of reciprocal telencephalic efferents to the dorsal thalamus and lack of local circuit neurons in reptiles (with the exception of the dorsal geniculate complex in turtles) and their presence in mammals. A thalamic reticular nucleus is present in both reptiles and mammals. In both of these classes of vertebrates, this neuronal aggregate surrounds the dorsal thalamus along its lateral surface, projects to the dorsal thalamus, and is organized into sectors. In one group of reptiles, Caiman crocodilus, the sole reptilian group in which immunocytochemical features have been investigated in detail, the reticular nucleus contains at least three neuronal subpopulations: neurons immunoreactive for glutamic acid decarboxylase (GAD); neurons immunoreactive for parvalbumin; and cells that are not immunoreactive for parvalbumin or, probably, GAD. On the other hand, the reticular nucleus of mammals contains a single population of neurons immunoreactive for GAD, gamma amino butyric acid, and parvalbumin.

Animals↗

[O-serovar distribution and antibiotic sensitivity of Pseudomonas aeruginosa strains from birds and reptiles].

100 strains of Pseudomonas aeruginosa (P.a.) from birds and reptiles were compared by determination of their O-serovars and their resistance to chemotherapeutic agents. A great number of isolates (birds 17.4%, reptiles 29.6%) were serologically untypable using 17 O-antisera by slide-agglutination-technique. The prevalence of O-serovar 0:6 was found in birds (39%) and reptiles (18.5%), followed by bird-isolates 0:1 and 0:3 (each 13%) and reptile-isolates 0:16 (14.8%). The serological distribution was different among bird- and reptile-isolates and also among the human and animal strains. All strains were resistant to penicillin G and ampicillin, more than 90% to nitrofurantoin, sulfamethoxazole-trimethoprim, chloramphenicol and erythromycin. Resistance to tetracycline was found to be 87%, resistance to sulfonamide 81%, respectively. 32% of all isolates were resistant to streptomycin, 61% to kanamycin. All isolates were susceptible to genta- and neomycin. Also all isolates, except one reptile-strain, were susceptible to gyrase-blocker (Bay VP 2674). 2 isolates were resistant to polymyxin B.

Animals↗

Comparison of the "mammal machine" and the "reptile machine": energy use and thyroid activity.

Oxygen consumption of tissue slices of liver, kidney, and brain were measured at 37 degrees C to assess in vitro metabolism of tissues of Amphibolurus nuchalis and Mus musculus (a reptile and mammal with same weight and body temperature). "Sodium transport" metabolism was also assessed (with use of ouabain) in these tissues. The mammal had an in vitro tissue metabolism that was two to five times that of the reptile and its sodium transport metabolism was four- to ninefold greater. Growth of reptile young and mammal young at the same body temperature was measured and the mammal showed a growth rate that was an order of magnitude greater than the reptile. Thyroid activity was assessed in the reptile and mammal by measurement of thyroidal uptake and release of 125I and serum thyroxine concentration. All parameters indicated a greater thyroid activity in the mammal. These findings are discussed in relation to the action of the thyroid hormones, the paleoecology of mammals and reptiles and the evolution of endothermy.

Aging↗

A comparative study of the metabolic capacity of hearts from reptiles and mammals.

The metabolic capacities of reptilian and mammalian hearts have been investigated using two methods: measurement of mitochondrial enzyme activity (cytochrome oxidase) and measurement of both mitochondrial volume density and membrane surface area. The heart tissues from the reptiles and mammals showed 2-fold "weight specific" and 3-fold total organ metabolic capacity differences. Heart mitochondria from reptiles and mammals showed 2-fold differences in the activity of their enzymes per mg of mitochondrial protein yet showed very similar mitochondrial surface areas per cm3 of mitochondria. Heart mitochondria differ from liver mitochondria which have the same enzyme activities per mg of protein and the same mitochondrial surface area per cm3 of mitochondria in both the reptiles and mammals. A wide variety of reptiles and mammals both showed relationships between total heart metabolic capacity and body weight. Mammals have larger hearts than similar sized reptiles and their hearts have a greater proportion of cellular volume occupied by mitochondria.

Animals↗

Fungal diseases of reptiles.

Fungal infections affecting the integumentary system, the upper and lower respiratory system and the gastro-intestinal tract have been reported in many species of captive reptiles. Systemic mycoses are diagnosed rarely in reptiles, and in most cases, they are a postmortem finding. Commonly, immunocompromised reptiles, kept in suboptimal environmental conditions are affected. In many cases, mixed bacterial and fungal infections of opportunistic organisms may be present. A diagnosis of a primary fungal infection is based on proper selection and collection of diagnostic specimens such as biopsies of infected tissues. Treatment of fungal infections in reptiles includes administration of effective antifungal agents and correction of inappropriate environmental conditions such as poor hygiene, too high or too low temperature and humidity, inadequate diet, and stress from overcrowding. Few studies have investigated effective dosages and dosage intervals of antifungal agents in reptiles.

Animals↗