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PubMed1999

Energetics of free-ranging mammals, reptiles, and birds.

We summarize the recent information on field metabolic rates (FMR) of wild terrestrial vertebrates as determined by the doubly labeled water technique. Allometric (scaling) relationships are calculated for mammals (79 species), reptiles (55 species), and birds (95 species) and for various taxonomic, dietary, and habitat groups within these categories. Exponential equations based on body mass are offered for predicting rates of daily energy expenditure and daily food requirements of free-ranging mammals, reptiles, and birds. Significant scaling differences between various taxa, dietary, and habitat groups (detected by analysis of covariance with P < or = 0.05) include the following: (a) The allometric slope for reptiles (0.889) is greater than that for mammals (0.734), which is greater than that for birds (0.681); (b) the slope for eutherian mammals (0.772) is greater than that for marsupial mammals (0.590); (c) among families of birds, slopes do not differ but elevations (intercepts) do, with passerine and procellariid birds having relatively high FMRs and gallinaceous birds having low FMRs; (d) Scleroglossan lizards have a higher slope (0.949) than do Iguanian lizards (0.793); (e) desert mammals have a higher slope (0.785) than do nondesert mammals; (f) marine birds have relatively high FMRs and desert birds have low FMRs; and (g) carnivorous mammals have a relatively high slope and carnivorous, insectivorous, and nectarivorous birds have relatively higher FMRs than do omnivores and granivores. The difference detected between passerine and nonpasserine birds reported in earlier reviews is not evident in the larger data set analyzed here. When the results are adjusted for phylogenetic effects using independent contrasts analysis, the difference between allometric slopes for marsupials and eutherians is no longer significant and the slope difference between Scleroglossan and Iguanian lizards disappears as well, but other taxonomic differences remain significant. Possible causes of the unexplained variations in FMR that could improve our currently inaccurate FMR prediction capabilities should be evaluated, including many important groups of terrestrial vertebrates that remain under- or unstudied and such factors as reproductive, thermoregulatory, social, and predator-avoidance behavior.

Animals↗
PubMed1981

Comparison of the "mammal machine" and the "reptile machine": energy production.

Standard metabolism and body composition were measured in Amphibolurus nuchalis and Mus musculus (a reptile and mammal with the same weight and body temperature). The metabolic capacity for energy production was assessed in liver, heart, brain, and kidney in the lizard and mouse by two methods: measurement of mitochondrial enzyme activity (cytochrome oxidase) and measurement of both mitochondrial volume density and membrane surface area. Both methods gave a three- to sixfold greater capacity for energy production in the mammal compared to the lizard which is less than the eightfold difference in their standard metabolisms. The difference in energy production capacity was not due to any single parameter but was a summation of several smaller differences. The mammal had relatively larger internal organs than the reptile, their organs had a greater proportion of mitochondria, and their mitochondria had a greater relative membrane surface area. These differences, it is suggested, may be due in part to different thyroid function in reptiles and mammals.

Animals↗
PubMed1997

Nucleotide sequences of reptile calcitonins: their high homology to chicken calcitonin.

The calcitonin genes of four species of reptiles (Reeve's turtle, rat snake, grass lizard, and spectacled caiman) were amplified from the genomic DNA, as well as from the mRNA of the ultimobranchial glands of the former three species, by the polymerase chain reaction (PCR) method, and were sequenced. Among several primer sets, only one primer set synthesized from the chicken calcitonin gene was compatible with those of the reptiles. The nucleotide sequences of the reptile calcitonin genes were highly homologous with that of chicken calcitonin (100% for turtle, 99% for caiman, 96% for lizard and 93% for snake). The products amplified from mRNA by the RT-PCR method matched completely those from genomic DNA in the turtle, snake and lizard.

Amino Acid Sequence↗
PubMed2001

The respiratory consequences of feeding in amphibians and reptiles.

Many ectothermic vertebrates ingest very large meals at infrequent intervals. The digestive processes associated with these meals, often coupled with an extensive hypertrophy of the gastrointestinal organs, are energetically expensive and metabolic rate, therefore, increases substantially after feeding (specific dynamic action, SDA). Here, we review the cardio-respiratory consequences of SDA in amphibians and reptiles. For some snakes, the increased oxygen uptake during SDA is of similar magnitude to that of muscular exercise, and the two physiological states, therefore, exert similar and profound demands on oxygen transport by the cardiorespiratory systems. In several species, SDA is attended by increases in heart rate and overall systemic blood flows, but changes in blood flow distribution remain to be investigated. In snakes, the regulation of heart rate appears to involve a non-adrenergic-non-cholinergic mechanism, which may be a regulatory peptide released from the gastrointestinal system during digestion. Digestion is also associated with a net acid secretion to the stomach that causes an increase in plasma HCO3- concentration (the 'alkaline tide'). Experiments on chronically cannulated amphibians and reptiles, show that this metabolic alkalosis is countered by an increased P(CO2), so that the change in arterial pH is reduced. This respiratory compensation of arterial pH is accomplished through a reduction in ventilation relative to metabolism, but the estimated reductions in lung P(O2) are relatively small. The SDA response is also associated with haematological changes, but large interspecific differences exist. The studies on cardiorespiratory responses to digestion may allow for a further understanding of the physiological and structural constraints that limits the ability of reptiles and amphibians to sustain high metabolic rates.

Amphibians↗
PubMed2001

Ticks (Acari: Ixodidae) spread by the international trade in reptiles and their potential roles in dissemination of diseases.

The international trade in live reptiles has grown dramatically in the last decade. Since many of these reptiles are infested with ticks, the number of ticks introduced to new exotic locations has also increased. This is causing concern in importing countries such as the United States because some of the reptilian ticks are known to be vectors of diseases of veterinary and economic importance, such as heartwater. Rational measures to control these tick species and to eradicate new introductions have been slow to develop due in part to the scattered and often obscure sources of available data on the exotic ticks. This review is an attempt to collate information on the geographical distribution, host range, life cycle and associations with diseases for four Amblyomma species, A. marmoreum Koch, A. nuttalli Dönitz, A. sparsum Newmann, and for four Aponomma species, A. exornatum (Koch), A. flavomaculatum (Lucas), A. latum (Koch)( and A. varanensis (Supino), that have recently been introduced into Florida, USA on imported reptiles.

Animals↗
PubMedDate not supplied

[Communication and auditory behavior obtained by auditory evoked potentials in mammals, birds, amphibians, and reptiles].

METHODS ANIMALS: amphibians, Frog catesbiana (frog bull, 30 animals); reptiles, Sceloporus torcuatus (common small lizard, 22 animals); birds: Columba livia (common dove, 20 animals), and mammals, Cavia porcellus, (guinea pig, 20 animals). With regard to lodging, all animals were maintained at the Institute of Human Communication Disorders, were fed with special food for each species, and had water available ad libitum. Regarding procedure, for carrying out analysis of auditory evoked potentials of brain stem SPL amphibians, birds, and mammals were anesthetized with ketamine 20, 25, and 50 mg/kg, by injection. Reptiles were anesthetized by freezing (6 degrees C). Study subjects had needle electrodes placed in an imaginary line on the half sagittal line between both ears and eyes, behind right ear, and behind left ear. Stimulation was carried out inside a no noise site by means of a horn in free field. The sign was filtered at between 100 and 3,000 Hz and analyzed in a computer for provoked potentials (Racia APE 78). RESULTS: In data shown by amphibians, wave-evoked responses showed greater latency than those of the other species. In reptiles, latency was observed as reduced in comparison with amphibians. In the case of birds, lesser latency values were observed, while in the case of guinea pigs latencies were greater than those of doves but they were stimulated by 10 dB, which demonstrated best auditory threshold in the four studied species. Last, it was corroborated that as the auditory threshold of each species it descends conforms to it advances in the phylogenetic scale. CONCLUSIONS: Beginning with these registrations, we care able to say that response for evoked brain stem potential showed to be more complex and lesser values of absolute latency as we advance along the phylogenetic scale; thus, the opposing auditory threshold is better agreement with regard to the phylogenetic scale among studied species. These data indicated to us that seeking of auditory information is more complex in more evolved species.

Amphibians↗
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↗
PubMed1990

Developmental mechanism involved in the embryonic reduction of limbs in reptiles.

The purpose of the studies here reported was to explain the mechanisms responsible for the reduction of limbs in the serpentiform reptiles. Descriptive and experimental embryology, ultrastructural studies, chemical action (with Ara-C) on embryos and (3H) thymidine autoradiography of limb buds were used in this study; they provide evidence that defects in the morphogenetic mechanisms involved in the development of limbs (somitic deficiency, incomplete differentiation and premature degeneration of the apical ectodermal ridge) are responsible for the cessation of growth of the limb buds in these reptiles. At the biochemical level, a strong decline in the rate of DNA synthesis in the mesodermal cells of the limb bud (during and after the degeneration of the apical ridge) is the main causative factor of the evolutionary arrest of limb development in serpentiform reptiles.

Animals↗
PubMedDate not supplied

[Taxonomic problems of the Leishmania of reptiles].

The history of description and state of knowledge of 17 species and 40 not identified to species forms of Leishmania, described from reptiles of the world, are traced. It is suggested to retain 10 species and 3 forms of Leishmania in the list of the subgenus Sauroleishmania as follows: L. (S) tarentolae, L.(S.) hemidactyli, L.(S.) ceramodactyli, L.(S.) nicollei, L.(S.) gymnodactyli, L.(S.) adleri, L.(S.) hoogstraali, L.(S.) senegalensis, L.(S.) gulikae, L.(S.) sp., L.(S.) sp. I, L.(S.) sp. II. 7 species and one form, L(S.) henrici, L.(S.) davidi, L.(S.) zmeevi, L.(S.) sofieffi, L.(S.) chameleonis, L.(S.) phrynocephali, L.(S.) helioscopi, L.(S.) sp. Markov e.a., 1964 must be excluded from the above subgenus since their description does not correspond to the development of the life cycle of Leishmania from reptiles. Flagellata Protozoa from the peripheral blood and intestine of reptiles, which were regarded by some authors as a "leptomonad stage of Leishmania", appear to belong to the genera Proteromonas, Monocercomonas and other Protozoa.

Animals↗
PubMed1971

Reptiles and their importance in the epidemiology of leishmaniasis.

Promastigote flagellates have been isolated from various species of lizard and from some other reptiles. It is known that sandflies readily feed upon lizards and it has been thought that reptiles could be a reservoir for mammalian leishmaniasis. A feature of reptilian infections is the extreme scarcity of parasites in blood smears and in tissue impression smears but isolations may readily be made in culture media. The intradermal inoculation of promastigote cultures from lizards into mammals and man induces a positive leishmanial response and gives rise to long-lasting dermal knots from which living parasites can be recovered for periods of several months.Associations between promastigotes and lizards in parts of the USSR, particularly in the Turkmenian SSR, and experimental work in the USSR on the transmission of promastigote strains to a variety of mammals, including gerbils, mice, monkeys, and man, are reviewed. The author accepts the generally held view that although promastigote flagellates of reptiles are important in an evolutionary context, having probably given rise to the mammalian leishmanias, present-day strains must be considered nonpathogenic for mammals.

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↗
PubMed1998

[Keeping reptiles].

Keeping of reptiles in captivity is permanently increasing. As there exists such a great number of species of reptiles, the conditions of the natural habitat of the kept species have to be imitated as exactly as possible. Disorders in reptiles are often caused by inadequate maintainance.

Animal Diseases↗
PubMed1980

Propriospinal fibers interconnecting the spinal enlargements in some quadrupedal reptiles.

The cells of origin, course and site of termination of long propriospinal fibers interconnecting the intumescences have been studied with the aid of the horseradish peroxidase technique, as well as with anterograde degeneration techniques, in some quadrupedal reptiles (the lizards Tupinambis nigropunctatus and Varanus exanthematicus, and the turtles Testudo hermanni and Pseudemys scripta elegans). The anterograde degeneration findings suggest that long descending propriospinal fibers from the cervical intumescence are distributed bilaterally to the ventral gray of the lumbar enlargement, including the lateral motoneuron column. Long ascending fibers from the lumbar to the cervical intumescence are distributed, also bilaterally, to the ventromedial part of area VII--VIII. The cells of origin of long descending propriospinal fibers wre found in the medial part of area VII--VIII in the cervical intumescence, particularly contralateral to the injection side. The cells of origin of long ascending propriospinal fibers were found in the lumbar intumescence, also particularly contralateral to the injection side, in the ventromedial part of area VII--VIII. It seems likely that in the reptiles studied the long propriospinal fibers interconnecting the spinal enlargements are in large part organized as crossed connections. The demonstration of long propriospinal fibers in lizards and turtles--i.e. quadrupedal reptiles that move their limbs in a particular diagonal pattern--suggests that these pathways are of great importance for the coordination of forelimb and hindlimb movements.

Afferent Pathways↗
PubMed2006

Dmrt1 expression in response to estrogen treatment in a reptile with temperature-dependent sex determination.

Dmrt1 has been implicated as an important factor in sex determination in all classes of vertebrates, including reptiles with temperature-dependent sex determination (TSD). Specifically, early embryonic expression of Dmrt1 appears to be an integral part of normal testicular development in vertebrates. Recently, a number of TSD studies have placed Dmrt1 expression at the top of a short list of putative temperature-sensitive events for TSD. Dmrt1 expression has been shown to be up-regulated at male-producing temperatures during the thermosensitive period (TSP) of several TSD reptile species. An interesting finding in Dmrt1 studies of fish and amphibians has been that in species where exogenous steroids can stimulate sex reversal, Dmrt1 expression can also be manipulated by these steroid treatments. In the current study, we examine the effects of exogenous 17beta-estradiol treatment on Dmrt1 expression at male-producing temperature (26 degrees C) in a reptile with TSD, the red-eared slider turtle, Trachemys scripta. Previous studies have demonstrated that exogenous estrogens can stimulate sex reversal (at male-producing temperatures) in this species of turtle. In the current study, T. scripta embryos that received estradiol treatment displayed a significant decrease in Dmrt1 expression during the TSP, while embryos in the control group (no estradiol treatment) showed significant increases in Dmrt1 expression during the TSP. Furthermore, the pattern of Dmrt1 expression for the estradiol-treated group was similar to the pattern we previously reported for Dmrt1 at female-producing temperature (31 degrees C). These findings indicate that exogenous estrogen is acting at or before the Dmrt1 event in the sex determination/sex differentiation cascade of T. scripta. Further, the results are consistent with the hypothesis that exogenous estrogen could be exerting its feminizing effect by down-regulating the expression of Dmrt1.

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↗
PubMedDate not supplied

Biosynthesis of multiple forms of beta-endorphin in the reptile intermediate pituitary.

Fractionation of the beta-endorphin-sized material from freshly dissected reptile intermediate pituitaries by ion exchange chromatography on sulfopropyl Sephadex (SP) revealed at least three distinct forms of immunoreactive beta-endorphin. These forms eluted at 0.25 M NaCl, 0.28 M NaCl, and 0.32 M NaCl and represent respectively, 6%, 65% and 29% of the total immunoreactivity. Only the 0.28 M NaCl peak and the 0.32 M NaCl peak exhibited naloxone reversible opiate bioactivity when tested in the isolated guinea pig ileum bioassay system; taking into account the molar amount of immunoreactive peptides the 0.32 M NaCl peak was 6 fold more potent than the 0.28 M NaCl peak. Intermediate pituitaries in culture were incubated with either [3H]tyrosine, [3H]arginine, or [35S]methionine for periods up to 24 hours and beta-endorphin-sized peptides were prepared by immunoprecipitation and gel filtration. Fractionation of the labeled beta-endorphin-sized peptides by ion exchange chromatography yielded profiles nearly identical to the immunoassay analyses of freshly dissected tissue. Further analysis of the major labeled forms of reptile beta-endorphin by chromatography on Sephadex G-50 equilibrated in 6 M guanidine HCl indicated that the 0.32 M NaCl peak had an apparent molecular weight of 3500 +/- 100 and the 0.28 M NaCl peak had an apparent molecular weight of 3200 +/- 100. Furthermore, pulse/chase experiments showed that the 0.32 M NaCl peak was the precursor for the 0.28 M NaCl peak. These results coupled with the relative opiate bioactivities of the major argue that the principal post-translational modification of reptile beta-endorphin is COOH-terminal proteolytic cleavage.

Animals↗
PubMed2001

Reptile anesthesia.

Successful reptile anesthesia requires patience, planning, and understanding of normal anatomy and physiology in health and disease. Reptiles make good anesthetic patients because of their physiologic resilience. New drugs that are not only safe and efficacious, but also result in relatively short recovery times, have greatly enhanced the design of anesthetic regimens. Further studies are required to quantitatively evaluate the physiologic effects of drugs used and validate available monitoring modalities for use in a wide variety of reptiles.

Anesthesia↗
PubMedDate not supplied

Dual actions of isthmic input to tectal neurons in a reptile, Gekko gekko.

We analyzed postsynaptic potentials and dye-labeled morphology of tectal neurons responding to electrical stimulation of the optic nerve and of the nucleus isthmi in a reptile, Gekko gekko, in order to compare with previously reported interactions between the optic tectum and the nucleus isthmi in amphibians and birds. The results indicate that isthmic stimulation exerts inhibitory and excitatory actions on tectal cells, similar to dual isthmotectal actions in amphibians. It appears that dual actions of the isthmotectal pathway in amphibians and reptiles are shared by two subdivisions of the nucleus isthmi in birds. The morphology of tectal cells responding to isthmic stimulation is generally similar to that of tectoisthmic projecting neurons, but they differ particularly in that some tectoisthmic cells bear numerous varicosities whereas cells receiving isthmic afferents do not. Thus, it is likely that at least some tectoisthmic cells may not be in the population of tectal cells that can be affected by isthmic stimulation. Forty-four percent of injections resulted in dye-coupled labeling, suggesting extensive electrical connections between tectal cells in reptiles.

Animals↗