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PubMed2005

Diseases and causes of mortality among sea turtles stranded in the Canary Islands, Spain (1998-2001).

This paper lists the pathological findings and causes of mortality of 93 sea turtles (88 Caretta caretta, 3 Chelonia mydas, and 2 Dermochelys coriacea) stranded on the coasts of the Canary Islands between January 1998 and December 2001. Of these, 25 (26.88%) had died of spontaneous diseases including different types of pneumonia, hepatitis, meningitis, septicemic processes and neoplasm. However, 65 turtles (69.89%) had died from lesions associated with human activities such as boat-strike injuries (23.66%), entanglement in derelict fishing nets (24.73%), ingestion of hooks and monofilament lines (19.35%), and crude oil ingestion (2.15%). Traumatic ulcerative skin lesions were the most common gross lesions, occurring in 39.78% of turtles examined, and being associated with Aeromonas hydrophila, Vibrio alginolyticus and Staphylococcus spp. infections. Pulmonary edema (15.05%), granulomatous pneumonia (12.90%) and exudative bronchopneumonia (7.53%) were the most frequently detected respiratory lesions. Different histological types of nephritis included chronic interstitial nephritis, granulomatous nephritis and perinephric abscesses, affecting 13 turtles (13.98%). Ulcerative and fibrinous esophagitis and traumatic esophageal perforation were the most frequently observed lesions in the esophagus, being associated in the majority of the cases with ingestion of fishing hooks. Larval nematodes of the Anisakidae family caused gastritis in 15 turtles (16.13%). Necrotizing and/or granulomatous hepatitis were the lesions most commonly observed in the liver (27.95%). Traumatic lesions included necrotizing myositis (10.75%) mainly caused by entanglement in fishing nets or boat-strikes, and amputation of 1 or 2 flippers (25.81%) by netting. Traumatic erosions and/or fractures of the carapace/plastron mainly caused by boat-strikes were also observed (26.88%). Eye lesions included heterophilic keratoconjunctivitis, ulcerative keratitis and heterophilic scleritis, affecting 7 turtles (7.53%).

Animal Diseases↗
PubMed2000

Persistent infectivity of a disease-associated herpesvirus in green turtles after exposure to seawater.

Herpesviruses are associated with several diseases of marine turtles including lung-eye-trachea disease (LETD) and gray patch disease (GPD) of green turtles (Chelonia mydas) and fibropapillomatosis (FP) of green, loggerhead (Caretta caretta), and olive ridley turtles (Lepidochelys olivacea). The stability of chelonian herpesviruses in the marine environment, which may influence transmission, has not been previously studied. In these experiments, LETD-associated herpesvirus (LETV) was used as a model chelonian herpesvirus to test viral infectivity after exposure to seawater. The LETV virus preparations grown in terrapene heart (TH-1) cells were dialyzed for 24 to 120 hr against aerated artificial or natural seawater or Hank's balanced salt solution (HBBS). Fresh TH-1 cells were inoculated with dialyzed LETV, and on day 10 post-infection cells were scored for cytopathic effect. Virus samples dialyzed up to 120 hr were positive for the herpesvirus DNA polymerase gene by polymerase chain reaction. Electron microscopy revealed intact LETV nucleocapsids after exposure of LETV to artificial seawater or HBSS for 24 hr at 23 C. LETV preparations remained infectious as long as 120 hr in natural and artificial seawater at 23 C. Similar results were obtained with a second culturable chelonian herpesvirus, HV2245. LETV infectivity could not be detected after 48 hr exposure to artificial seawater at 30 C. Since LETV and HV2245 remain infectious for extended periods of time in the marine environment, it is possible that FP-associated and GPD-associated herpesviruses also may be stable. These findings are significant both for researchers studying the epidemiological association of herpesviruses with diseases of marine turtles and for individuals who handle turtles in marine turtle conservation efforts.

Animals↗
PubMed2000

[Salmonella infection from turtles].

Small turtles are asymptomatic carriers of Salmonella. Infants are particularly at risk of clinical infection. We describe an eight months old boy who became sick with Salmonella. The family had two turtles. Salmonella Abony was found in faeces from the child and in samples from both turtles. Commercial distribution of reptiles is prohibited in Norway. However, illegal import from other countries where no such ban exist is common. There are an estimated 10,000 pet reptiles in the Oslo region, most of them are turtles. More than 90% of turtles may be carriers of Salmonella. Many owners of turtles are not aware of the risk of salmonellosis from their pets.

Animals↗
PubMed1977

Food and oxygen requirements for growing mice and turtles after hypergravitational development.

Although development of mice and turtles, both low-payload animals, can be influenced by ambient gravitational intensity, little is known regarding the influence of either their growth or their gravitational history upon life-support requirements. A 25-g male Box Turtle (Terrapene carolina, optimally growing at 30 degrees C and 1 G to double its size in 7 weeks) exhibits daily requirements of oxygen (100 ml) and food (200 mg, dry) which are only 3% of the requirement for a mouse (Swiss Webster, centrifuged at 22 degrees) of comparable size and growth rate. These requirements grow in proportion to the turtle's (body mass)0.9 and to the mouse's (body mass)0.5. After development at hypergravity g (of from 1.5 to 5 G expressed in multiples of the earth's gravity) there is a one-day delay for turtles but an immediate change for mice in these requirements upon return to 1 G. Although both show a decreased oxygen intake, the drop is greater for turtles (equalling g -0.4 of the baseline value, as corrected for body size, after return from 75 days exposure against g-0.08 for mice after 1-13 days exposure); the food intake drops for turtles (varies as g-1) while it rises for mice (varies as g0.6).

Animals↗
PubMed2005

Salmonellosis associated with pet turtles--Wisconsin and Wyoming, 2004.

Salmonellosis associated with small pet turtles in the United States was a major public health concern in the 1970s. In 1975, the Food and Drug Administration (FDA) banned commercial distribution of small turtles (i.e., those with a carapace of <4 inches). The FDA ban prevents an estimated 100,000 cases of salmonellosis among children each year. However, a recent resurgence in the sale of small turtles has generated concern. In Wisconsin and Wyoming, at least six human cases of salmonellosis have been linked to such turtles. This report describes the investigation into those cases. The findings underscore the need for health and environmental officials to prevent illegal distribution of small turtles and consider patient contact with turtles when investigating salmonellosis cases.

Aged↗
PubMed1990

[Development of the subclavian artery in the loggerhead turtle (Caretta caretta) studied by the injection method].

In the turtle, the left aorta and the pulmonary trunk originate from the right ventricle, while the right aorta takes its origin from the left ventricle as a functional systematic arch. The subclavian artery arises from the brachiocephalic artery on each side, and passes ventral to the vagus nerve and the jugular vein. These features are basically the same as in birds, and the subclavian artery of the adult turtle corresponds to a secondary artery from the viewpoint of comparative anatomy. Many investigators, including one of the present authors (Suzuki, 1987), have studied the development of the aortic arch and the subclavian artery in the chick embryo, but not in the turtle. The present authors examined it in Loggerhead turtle (Caretta caretta) embryos, from 14 days of incubation to completion of the aortic arch (27 days incubation). All blood vessels were injected with Berlin blue solution using a fine glass needle inserted into the aortic trunk through the ventricle of the heart. The following results were obtained. 1. In the turtle embryo the primary subclavian artery develops first, but is replaced by the secondary subclavian artery as in the chick. 2. The primary subclavian artery arises from the 12th dorsal intersegmental artery and passes dorsal to the posterior cardinal vein. In the 16-day embryo, it gives rise to capillary nets both cranially and caudally at the base of the forelimb bud along the inner surface of the thoracic wall. 3. At 19 days of incubation, a small blood vessel arises from the aortic sac at the origin of the third aortic arch and passes laterally, ventral to the anterior cardinal vein. The vessel then extends caudally, and finally, at 21 days of incubation, connects to the cranial part of the capillary net of the primary subclavian artery at about the middle of the lateral thoracic wall. After the completion of the connection, the vessel from the aortic sac is called by the name "the secondary subclavian artery." 4. The secondary subclavian artery gradually increases in size, while the proximal part of the primary one begins to atrophy and finally disappears at 27 days of incubation. After this, the forelimb bud receives its blood supply only from the newly-formed secondary subclavian artery. 5. In conclusion, in the turtle, the secondary subclavian artery is formed by connection of the primary artery with the caudally extending artery arising from the aortic sac, while in the chick it is derived from an outgrowth of the primary artery.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2006

[Effects of eight methods of intelligent turtle on free radical metabolism in the kidney-yang deficiency model guinea pigs].

OBJECTIVE: To observe effects of moxibustion according to opening points on time in eight methods of intelligent turtle on aging and the mechanism. METHODS: Healthy and adult guinea pigs were randomly divided into 5 groups, a prevention group of kidney-yang deficiency model with eight method of intelligent turtle (group I), a prevention group of kidney-yang deficiency model (group II) with moxibustion at Mingmen (GV 4), a group of treatment group of kidney-yang deficiency model with eight methods of intelligent turtle (group III), a treatment group of kidney-yang deficiency model (group IV) with moxibustion at Mingmen (GV 4) and a control group of kidney-yang deficiency. Effects of moxibustion according to opening on time in eight methods of intelligent turtle and moxibustion at Mingmen (GV 4) on superoxide dismulase (SOD) activity and malondialdehyde (MDA) level were compared. RESULTS: After modeling, no signs of kidney-yang deficiency and no significant changes of SOD and MDA were found in group I and II; but obvious symptoms of kidney-yang deficiency and decrease of SOD (P < 0.01) and increase of MDA (P < 0.01 or P < 0.05) were found in group III, IV and V; after treatment, in the group III); the symptoms of kidney-yang deficiency basically disappeared, SOD increased (P < 0.01) and MDA decreased (P < 0.01), with no significant differences as compared with those before modeling (P > 0.05); in the group N, the symptoms of kidney-yang deficiency significantly improved and SOD increased (P < 0.05) with difference as compared with those before modeling (P < 0.05), and MDA decreased (P < 0.05), but with no significant difference compared with that before modeling (P > 0.05); the symptoms of kidney-yang deficiency, SOD and MDA did not significantly change in group V (P > 0. 05). CONCLUSION: Both moxibustion according to opening points on time in eight methods of intelligent turtle and moxibustion at Mingmen (GV 4) can effectively regulate free radical metabolism and have obvious action of preventing and treating kidney-yang deficiency in the model guinea pigs, and the therapeutic action of moxibustion according to opening points on time in eight methods of intelligent turtle is better than that of moxibustion at Mingmen (GV 4).

Animals↗
PubMed1986

Conjunctivitis, tracheitis, and pneumonia associated with herpesvirus infection in green sea turtles.

Fourteen juvenile (15- to 20-month-old) green sea turtles (Chelonia mydas), representative of a group of sea turtles with clinical signs of respiratory tract disease, were euthanatized and submitted for necropsy. Macroscopically, lesions included periglottal necrosis, tracheitis with intraluminal caseous and laminated necrotic debris, and severe pneumonia. Several turtles had caseous conjunctival exudate covering the eyes. Microscopically, the turtles had fibrinonecrotic inflammation around the glottal opening, tracheitis, and severe bronchopneumonia and interstitial pneumonia. In multifocal areas, periglottal and tracheal epithelial cells adjacent to areas of necrosis had hypertrophic nuclei with amphophilic intranuclear inclusions. A mixed population of primarily gram-negative microorganisms was isolated from the tracheal and glottal lesions. Attempts at viral isolation in cultures of green sea turtle kidney cells resulted in the development of cytopathic effects characterized by giant cell formation and development of intranuclear inclusions. Using electron microscopy, intranuclear viral particles (88 to 99 nm in diameter) were seen in inclusion-containing tracheal and glottal epithelial cells and infected green sea turtle kidney cells; particles were consistently seen enveloping from nuclear membranes, and mature particles (132 to 147 nm) were found in the cytoplasm. On the basis of size, conformation, location, and presence of an envelope, the particles most closely resembled those of herpes-viruses.

Animals↗
PubMed1980

Organochlorine residues in eggs of loggerhead and green sea turtles nesting at Merritt Island, Florida--July and August 1976.

Eggs from nine clutches of loggerhead turtles (Caretta caretta) and two clutches of green turtles (Chelonia mydas) were collected as they were laid on Merritt Island, Florida. Eggs were incubated, frozen, and analyzed for organochlorines. Levels of DDE and PCB, the major contaminants, averaged less than 0.08 ppm in loggerhead eggs and were even lower in green turtle eggs. These concentrations are far below levels thought to be potentially harmful. Loggerhead eggs were frozen after 43-52 days incubation; both DDE and PCB declined significantly during this interval. Authors estimate that DDE averaged about 0.2 ppm in loggerhead eggs when they were laid. DDE levels in eggs of both turtle species were less than levels in eggs of crocodiles (Crocodylus acutus) from Everglades National Park and in eggs of 13 species of aquatic birds nesting on Merritt Island. The remarkably low residues in the turtle eggs probably indicate that, when not nesting, the turtles live and feed in areas remote from Florida.

Animals↗
PubMed1998

Chelonacarus elongatus n. gen., n. sp. (Acari: Cloacaridae) from the cloaca of the green turtle Chelonia mydas (Cheloniidae).

Chelonacarus elongatus n. gen., n. sp. is proposed for a cheyletoid mite (Acari: Prostigmata) of the family Cloacaridae found in the cloacal tissue of the endangered green turtle Chelonia mydas Linnaeus, 1758 from the Atlantic coast of the Republic of Panama. In females, the new genus is distinguished from other genera of turtle cloacarids by the elongate slender shape of the idiosoma, the shape and pattern of sclerotization of the dorsal shield, and the fused distal ends of apodemes II. A combination of other features that distinguish the newly proposed genus is the smooth surface of the pedipalps, single dorsal spine on tibiae I-IV, no setae on coxa IV, terminal position of the vulva, and the strongly developed pair of ventral spines on tarsi I-II. This is the first record of cloacarids from sea turtles. The similarity of adult cloacarids in the genus Chelonacarus from sea turtles (Chelonioidea) and Cloacarus Camin et al., 1967 from snapping turtles (Chelydridae) lends support to the hypothesis of some paleontologists that these 2 groups of turtles are linked phylogenetically.

Animals↗
PubMed1998

Hatchling sea turtles use surface waves to establish a magnetic compass direction

Hatchling sea turtles emerge from underground nests, crawl to the ocean, and swim away from the land. In shallow water near shore, hatchlings maintain offshore headings by swimming into oceanic waves; in deeper water, however, turtles appear to rely on different mechanisms to maintain their courses. To determine whether loggerhead hatchlings, Caretta caretta L., are able to transfer a course initiated on the basis of waves to a course maintained by a magnetic compass, we studied the orientation behaviour of turtles that had been exposed to waves for either 15 or 30 min before being tested in still water. Hatchlings that swam into waves for 15 min failed to continue swimming on similar courses when the waves were discontinued, but turtles that swam into waves for 30 min maintained similar mean headings after the waves stopped. Inverting the vertical component of the magnetic field during the test period reversed the direction of orientation of this latter group of turtles. Thus, hatchlings can transfer a heading induced by waves to a magnetic compass, and thereby continue to migrate away from land after contact with the coast is lost. Migratory orientation in turtles resembles that of birds in that both rely on multiple cues and an ability to transfer information between various cues and compasses at appropriate times during the journey.Copyright 1998 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1998

Comparison of cortically and subcortically controlled motor systems: I. Morphology of intracellularly filled rubrospinal neurons in rat and turtle.

The rat and turtle differ markedly in major structural features of the corticocerebellorubrospinal circuitry. Although both species have a well-developed cerebellorubrospinal system, they differ in that a direct cerebral cortical input to the red nucleus is present only in the rat. The aim of the present study was to compare features of the soma and dendritic morphology of rubrospinal neurons that receive cortical input, as in rats, with those that do not, as in turtles. Intracellular Lucifer Yellow injections of neurons retrogradely labeled with Fast Blue in the rat or activity-dependent sulforhodamine-labeled neurons in the turtle were used to fill rubrospinal neurons in 150-200-microm-thick fixed sections. Images of filled neurons were imported into a computer to analyze quantitatively soma and dendritic morphology. The results show that rubrospinal soma size is slightly larger in the rat than in the turtle. However, analysis of the dendritic morphology, including total dendritic length, length of primary, secondary, and tertiary dendritic branches, and a Scholl analysis of dendritic branch intersections across concentric rings, demonstrated no significant differences between the two species. These findings suggest that the basic dendritic morphology of rubrospinal neurons may have been established early in phylogeny, preceding the evolution of cortical inputs. Alternatively, similar dendritic morphologies may have arisen due to the presence of other synapses in the turtle that occupy the sites of the cortical input in the rat. This comparative approach provides insights into the information processing capabilities of cortically versus subcortically controlled motor systems.

Animals↗
PubMed1996

Fine structure of the dorsal lingual epithelium of the juvenile hawksbill turtle, Eretmochelys imbricata bissa.

BACKGROUND: Various species of turtles are adapted to different environments, such as freshwater, seawater, and terrestrial habitats. Comparisons of histological and ultrastructural features of the tongue of the juvenile Hawksbill turtle, Eretmochelys imbricata bissa, with those of freshwater turtles should reveal some aspects of the relationship between the structure of the lingual epithelium and the environment. METHODS: The light microscope, scanning electron microscope and transmission electron microscope were used. RESULTS: Light microscopy revealed that the mucosal epithelium of the tongue was of the keratinized, stratified squamous type. Under the scanning electron microscope, no lingual papillae were visible on the dorsal surface of the tongue. Micropits and the thickening of cell margins were clearly seen on the surface of cells located on the outermost side. The transmission electron microscope revealed that the cells in the intermediate layer were gradually flattened from the basal side to the surface side, as were their nuclei. In the shallow intermediate layer, the cells were significantly flattened, and their nuclei were condensed or had disappeared. The cytoplasm contained keratohyalin granules, tonofibrils, free ribosomes, mitochondria, and rough endoplasmic reticulum. Numerous free ribosomes were attached to the surface of small keratohyalin granules. The cells of the keratinized layer were significantly flattened, and their nuclei had completely disappeared. Most of cytoplasm was filled with keratin fibers of high electron density. Keratin fibers of the shedding cells, which were located on the outermost side of the keratinized layer, appeared looser, and each fiber, which was somewhat thicker than the tonofibrils and tonofilaments, was clearly distinguishable. CONCLUSIONS: The lingual epithelium of the juvenile Hawksbill turtle differs significantly from that of the adult freshwater turtle, in spite of the similarity in gross morphology of the tongues of these species.

Adaptation, Physiological↗
PubMed1993

Ectoplasmic ("junctional") specializations in Sertoli cells of the rooster and turtle: evolutionary implications.

Ectoplasmic specializations are complex actin-containing structures found at certain sites of intercellular attachment in Sertoli cells. Current evidence indicates that these structures are a form of actin-associated adhesion junction. In the turtle (Pseudemys scripta) and rooster (Gallus domesticus) ectoplasmic specializations are known to occur adjacent to sites of attachment to elongate spermatids and are characterized by a layer of "loosely" cross-linked actin filaments that lies next to the plasma membrane. In the turtle, a cistern of endoplasmic reticulum is associated with the cytoplasmic face of the filament layer. We have found that, in fixed frozen sections of turtle and rooster testes, immunological probes for myosin II react with epithelial regions that also stain with probes for filamentous actin and that are known to be sites at which ectoplasmic specializations occur. Furthermore, when exposed to standard contraction buffers, the diameters of glycerinated ectoplasmic specializations of the turtle are statistically smaller than those of the same structures exposed to control buffers. We interpret these smaller diameters as being produced by the contraction of actin bundles within the ectoplasmic specializations. Our results indicate that ectoplasmic specializations in the rooster and turtle, unlike those in mammals, possess contractile properties. We speculate that ectoplasmic specializations in eutherian mammals may have evolved from actin-associated adhesion junctions in which the actin bundles were initially contractile and from which myosin II was secondarily lost.

Actins↗
PubMed1983

Characterization and quantification of peptidergic amacrine cells in the turtle retina: enkephalin, neurotensin, and glucagon.

Immunocytochemical methods were used for selective labeling and characterization of amacrine cells of the turtle (Pseudemys scripta elegans) retina which contained neuropeptide-like immunoreactivity (leu-enkephalin, glucagon, and neurotensin). Processes of amacrine cells arborized in specific strata of the inner plexiform layer (IPL). Different strata were defined in relation to the boundaries of the IPL. Zero represented the strata nearest the inner nuclear layer and 100 represented the strata nearest the ganglion cells. Antisera directed against leu-enkephalin labeled approximately 7,300 amacrine cells in a single turtle retina which were concentrated in the region of the visual streak and decreased in density toward the periphery. In retinal regions outside the visual streak the labeled neurons were similar in size and shape with dendritic arbors which lacked a particular orientation. In contrast, in the visual streak, there were particular neurons which were labeled with enkephalin antiserum which had elongated dendritic arbors that ran parallel to the streak. Both types of amacrine cells with enkephalinergic immunoreactivity sent their dendrites into the 0-20 region and the 65-100 region of the IPL. Antisera directed against glucagon labeled approximately 2,500 amacrine cells in a single turtle retina. These cells were concentrated in areas near the visual streak. Amacrine cells labeled with glucagon antiserum had dendritic arbors which were asymmetrically skewed toward one end of the cell and ramified in the 0-20 strata with sparse projections at the 40 and 80 strata of the IPL. Antisera directed against neurotensin labeled 12,800 amacrine cells in a single turtle retina. These cells were concentrated in the region of the visual streak. Two distinct amacrine cell types were labeled selectively. One type had a large, vertically oriented cell body (10 X 14 micron) which gave rise to a single 2-micron-thick process that branched and ramified within the 45-70 strata. The other amacrine cell type with neurotensin-like immunoreactivity had a smaller cell body (8 micron) that sent numerous thin dendrites into the same 45-70 strata. The present results indicated that various neuropeptides were present in amacrine cells of the turtle retina and that a specific neuropeptide could be found in more than one anatomical type of amacrine cell. Each anatomical type of amacrine cell had a unique dendritic arborization which ramified within particular strata within the IPL.

Animals↗
PubMed1984

The distribution of substance P in turtle nervous system: a radioimmunoassay and immunohistochemical study.

The distribution of a substance P-like material in turtle brain, spinal cord, dorsal root ganglion, and retina was determined using radioimmunoassay (RIA) and immunohistochemistry. High levels of a substance P-like material were found in turtle neural tissue, particularly in basal telencephalon, hypothalamus, and tegmentum. In many regions, the concentration of a substance P-like material in turtle nervous tissue was found to be similar, in a region-to-region comparison, to that previously reported for birds and mammals, particularly for the more "phylogenetically conservative" parts of the nervous system (such as the basal ganglia, tegmentum, and hypothalamus). The slopes of substance P RIA dose-response curves for tissue extracts from nearly all regions of the turtle nervous system examined were parallel to a standard dose-response curve for synthetic substance P (SP). The immunohistochemical results, with anti-substance P antisera from guinea pig or rabbit, or with a monoclonal antibody, were consistent with the RIA data. Regions showing high concentration of an SP-like material by RIA were observed to contain numerous neurons and/or fibers containing an SP-like material. The immunohistochemical results provide evidence for the presence in turtle of numerous SP-containing pathways, several of which (e.g., an SP-containing strionigral pathway, an SP-containing striopallidal pathway and an SP-containing dorsal root ganglia-spinal dorsal horn pathway), have been described in birds and mammals. The present results thus suggest that the neuropeptide SP has had a largely stable evolutionary history as a transmitter or modulatory agent during amniote brain evolution.

Animals↗
PubMed1991

Appearance of putative amino acid neurotransmitters during differentiation of neurons in embryonic turtle cerebral cortex.

Pyramidal and nonpyramidal neurons can be recognized early in the development of the cerebral cortex in both reptiles and mammals, and the neurotransmitters likely utilized by these cells, glutamate and gamma-aminobutyric acid, or GABA, have been suggested to play critical developmental roles. Information concerning the timing and topography of neurotransmitter synthesis by specific classes of cortical neurons is important for understanding developmental roles of neurotransmitters and for identifying potential zones of neurotransmitter action in the developing brain. We therefore analyzed the appearance of GABA and glutamate in the cerebral cortex of embryonic turtles using polyclonal antisera raised against GABA and glutamate. Neuronal subtypes become immunoreactive for the putative amino acid neurotransmitters GABA and glutamate early in the embryonic development of turtle cerebral cortex, with nonpyramidal cells immunoreactive for GABA and pyramidal cells immunoreactive for glutamate. The results of controls strongly suggest that the immunocytochemical staining in tissue sections by the GABA and glutamate antisera corresponds to fixed endogenous GABA and glutamate. Horizontally oriented cells in the early marginal zone (stages 15-16) that are GABA-immunoreactive (GABA-IR) resemble nonpyramidal cells in morphology and distribution. GABA-IR neurons exhibit increasingly diverse morphologies and become distributed in all cortical layers as the cortex matures. Glutamate-immunoreactive (Glu-IR) cells dominate the cellular layer throughout development and are also common in the subcellular layer at early stages, a distribution like that of pyramidal neurons and distinct from that of GABA-IR nonpyramidal cells. The early organization of embryonic turtle cortex in reptiles resembles that of embryonic mammalian cortex, and the immunocytochemical results underline several shared as well as distinguishing features. Early GABA-IR nonpyramidal cells flank the developing cortical plate, composed primarily of pyramidal cells, shown here to be Glu-IR. The earliest GABA-IR cells in turtles likely correspond to Cajal-Retzius cells, a ubiquitous and precocious cell type in vertebrate cortex. Glutamate-IR projection neurons in vertebrates may also be related. The distinctly different topographies of GABA and glutamate containing cells in reptiles and mammals indicate that even if the basic amino acid transmitter-containing cell types are conserved in higher vertebrates, the local interactions mediated by these transmitters may differ. The potential role of GABA and glutamate in nonsynaptic interactions early in cortical development is reinforced by the precocious expression of these neurotransmitters in turtles, well before they are required for synaptic transmission.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2001

Negative test for cloacal drinking in a semi-aquatic turtle (Trachemys scripta), with comments on the functions of cloacal bursae.

Many aquatic turtles possess paired evaginations of the cloaca called cloacal bursae. Despite more than two centuries of study, little consensus exists as to the function(s) of these organs. We tested a recent suggestion that bursae could function in water uptake ("cloacal drinking"). Turtles (Trachemys scripta) were dehydrated (68-86% of maximum body mass) and given the opportunity to drink orally or cloacally. Dehydration caused increases in hematocrit and osmolality of extracellular fluid (ECF), but only after loss of 10-12% of maximum body mass, suggesting that turtles osmoregulated by reabsorbing water from the urinary bladder. Turtles drank eagerly when they could submerge their heads, and drinking was accompanied by an increase in body mass and a decrease in ECF osmolality. However, dehydrated turtles with tail and anus submerged showed no changes in mass or osmolality, suggesting that water absorption is not a significant function of the cloacal bursae in this species. Evidence for other putative functions is reviewed, leading to a pluralistic view: in cryptodires, bursae apparently function primarily in buoyancy control and secondarily in ion transport and nesting, but several pleurodires have been shown recently to use them in aquatic respiration.

Absorption↗