Multirecording of Ca(2+) signals from inner retinal neurons evoked by light stimulation of photoreceptors.
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We simultaneously monitored changes of intracellular free Ca(2+) concentration ([Ca(2+)](i)) following different light stimuli from different inner retinal neurons of the turtle retina slice preparation. [Ca(2+)](i) increased with an increase of the light stimulus intensity. Some of the cells also showed color opponent Ca(2+) signals. 2-Amino-4-phosphonobutyric acid (APB) blocked in particular [Ca(2+)](i) increases and picrotoxin enhanced the observed [Ca(2+)](i) changes. These data support the idea that the observed [Ca(2+)](i) changes result from light stimulation and subsequent retinal processing. Similar Ca(2+) signals were observed when the release of Ca(2+) from internal stores was blocked with caffeine and thapsigargin. These results indicate that retinal Ca(2+) signals evoked by light stimulation depend to a large extent on voltage-dependent Ca(2+) influx and might therefore reflect signal processing. (+info)
Antibacterial effect of chloramphenicol, thiamphenicol and florfenicol against aquatic animal bacteria.
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The minimum inhibitory concentration (MIC) was measured to evaluate the antibacterial activities of chloramphenicol (CP), thiamphenicol (TP) and florfenicol (FFC) against the aquatic bacterial isolates from soft-shell turtles, fish and shellfish. Amoxicillin (AMPC), oxytetracycline (OTC) and oxolinic acid (OA) were included to compare with above protein synthesis inhibitors. The results showed that the order of MIC range of the isolates from soft-shell turtles for tested drugs was OA>FFC, CP>TP> AMPC, OTC. The percentage of the resistant strains indicated that OA was the lowest (7.14%) and OTC was the highest (85.07%). The order of antibacterial activity against the isolates from fish was OA>FFC>CP>AMPC>OTC>TP. The percentage of the resistant strains revealed that OA (13.64%) and OTC (80.91%) were the lowest and the highest, respectively. For the isolates from shellfish, the order of antimicrobial activity was OA>CP, FFC>AMPC, OTC, TP. TP showed the greatest percentage of the resistant strains (58.7%), but that of OA was the lowest (4.35%). The most common resistant patterns of the isolates from turtles, fish and shellfish were AMPC-OTC, CP-TP-AMPC-OTC, and FFC-CP-TP-AMPC-OTC, respectively. There were partially-complete resistance of the resistant isolates among CP, TP and FFC. The findings indicated that previous treatment might affect the choice of drug to use for aquatic bacterial diseases. (+info)
Chemical and thermal effects on the viability and motility of spermatozoa from the turtle epididymis.
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The viability and motility of spermatozoa harvested from the epididymides of turtles were estimated to elucidate properties that might enable them to be stored over long periods of time. Spermatozoa from the painted turtle, Chrysemys picta, were analysed and compared with spermatozoa from two other turtles, Trachemys scripta and Sternotherus odoratus using the Cellsoft analysis system for videotaped images. Spermatozoa from C. picta and T. scripta, suspended in F-10 medium, showed low motility (3-6% motile) and motion velocities, whereas the motility of spermatozoa from S. odoratus was higher (40% motile). Spermatozoa from C. picta and S. odoratus, but not T. scripta, had higher motilities and motion velocities when incubated at 2 degrees C before analyses. C. picta spermatozoa were unresponsive to calcium concentrations ranging from 10(-8) to 10(-1) mol l(-1), potassium concentrations ranging from 0. 1 to 10 mmol l(-1), and to pH values in the range 5.9-8.4. Spermatozoa from C. picta were sensitive to hypo-osmotic media, and showed reduced motility at 25% of normal osmolarity and no motility at 10% of normal osmolarity. Distorted cells and missing flagellae were noted at 50% of normal osmolarity. C. picta spermatozoa were viable up to 40 days after harvest when incubated at 4 degrees C; during this time, both motility and motion velocity were increased in response to 0.5 mmol 3-isobutyl-1-methylxanthine l(-1). Spermatozoa from turtles have osmotic properties and resistance to changing chemical environments similar to spermatozoa from other vertebrates that have internal fertilization, and appear to be stable over long periods of time compared with spermatozoa from other vertebrate species. (+info)
Villiform processes in the pharynx of the soft-shelled turtle, Trionyx sinensis japonicus, functioning as a respiratory and presumably salt uptaking organ in the water.
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Some species of soft-shelled turtle have been known to use a conspicuous mass of villiform processes of the pharyngeal mucosa as an aquatic respiratory organ when staying underwater for prolonged periods, such as hibernation. Using hibernating turtles, Trionyx sinensis japonicus, the present study employed scanning electron microscopy to demonstrate for the first time the detailed morphology and distribution of these villiform processes. Two types of processes, complex and simple, could be identified. Light microscope observation of the transverse sections of the villi demonstrated a rich vascularization in the connective tissue of the villi, comprising arterioles and venules running in the core and capillaries in the periphery. Most of the capillaries were invaginated into the multilayered cuboidal epithelium. Near the tip of the villi they became swollen, forming sinusoidal capillaries. Transmission electron microscopy clarified the fine structure of the blood-water barrier, which consisted of a non-fenestrated endothelium and an attenuated epithelium that sandwiched a connective tissue with a discontinuous subendothelial and a continuous subepithelial basement lamina. The epithelium consisted of secretory cells, mitochondria-rich cells, and basal cells. The mitochondria-rich cells contained a cytoplasmic area filled with tubulovesicular elements. Based on their ultrastructural resemblance with the chloride cells in the fish and tadpole, these cells are suggested to be involved in the uptake of Na+ and Cl from fresh water for keeping ionic balance in the blood. (+info)
The vascular supply of the villiform processes in the pharynx of the soft-shelled turtle, Trionyx sinensis japonicus. A scanning electron microscopic study of corrosion casts.
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Following our observations of the fine structure of the pharyngeal villiform processes of the hibernating soft-shelled turtle, Trionyx sinensis japonicus (Yokosuka et al., 2000), this paper deals with a scanning electron microscope study of the resin casts of blood vessels supplying those processes. Each villiform process contained arterioles and venules which ran in the axial portion of the process; capillaries formed a network at the periphery of the connective tissue core of the villus. In the distal portions of the villus, the capillaries increased markedly in their caliber to form sinusoidal capillaries. Such a vascular architecture supports the view that the villiform processes serve in the aquatic respiration of the soft-shelled turtle. The casts indicated an occurrence of sphincters in the vascular bed of the villi. (+info)
Evaluation of methods for the isolation of Salmonella and Arizona organisms from pet turtles treated with antimicrobial agents.
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Turtles infected with and actively excreting Salmonella-Arizona organisms were treated with various concentrations of both Neo-Terramycin (N-Te) and Terramycin (Te) (Pfizer) for various periods of time and then tested for the presence of these pathogens by two methods, excretion and blending. Turtles treated with 200 mug of Te per ml of container water for 9, 12, or 14 weeks, whereas when representative turtles from treatment groups were blended 72 h posttreatment these organisms were isolated from the whole turtle homogenate. Salmonella and Arizona could be recovered from homogenate prepared from turtles treated for 7 and 14 days with 400, 800, or 1,000 mug of Te or N-Te per ml. These findings suggest that the blending methods is more sensistive than the excretion method for the detection of Salmonella-Arizona in the treated turtle. (+info)
Maintenance of neutral buoyancy by depth selection in the loggerhead turtle Caretta caretta.
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Time-series data of swimming speed and dive depth were recorded in six female loggerhead turtles Caretta caretta during the internesting period. The dive profiles of all animals indicated that they stayed at particular depths without swimming and that these depths were correlated with dive duration. These results support the hypothesis that lung air is used to achieve neutral buoyancy in the loggerhead turtle. To test this hypothesis, female turtles were equipped with lead weights and time/depth recorders. The residence depth of the turtles increased when their specific gravity was artificially decreased. This indicates that they control depth rather than lung volume, suggesting that the residence depth of loggerhead turtles during the internesting period is not determined actively. They presumably remain at a particular depth exclusively to save energy for egg maturation during the internesting period. Lung volume was estimated from the change in depth of weighted animals to be 50-150 ml kg(-1). The resulting residence depth of all turtles was within the range at which they maintained the neutral buoyancy. (+info)
The existence of Na+/K+-ATPase-immunoreactive cells in the pharyngeal villiform-papilla epithelium of the soft-shelled turtle, Trionyx sinensis japonicus.
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The pharyngeal villiform processes of the hibernating soft-shelled turtle, Trionyx sinensis japonicus, were studied by immunohistochemistry for Na+/K+-ATPase in combination with a mitochondrion staining. Mitochondria-rich cells were recognized in the epithelium constituting the distal part of most processes, and exclusively showed the Na+/K+-ATPase immunoreactivity. These cells tended to attract each other to form clusters. When considering the physiological and histological data previously obtained in corresponding cells in the fish gill epithelium, the mitochondria-rich cells in the hibernating turtle were suggested to be involved in the electrolyte (Na+) uptake from the aquatic habitat. (+info)