| molecular cloning and characterization of estrogen, androgen, and progesterone nuclear receptors from a freshwater turtle (pseudemys nelsoni). | steroid hormones are essential for the normal function of many organ systems in vertebrates. reproductive activity in females and males, such as the differentiation, growth, and maintenance of the reproductive system, requires signaling by the sex steroids. although extensively studied in mammals and a few fish, amphibians, and bird species, the molecular mechanisms of sex steroid hormone (estrogens, androgens, and progestins) action are poorly understood in reptiles. here we evaluate hormone re ... | 2008 | 17916628 |
| molecular characterization of alpha-keratins in comparison to associated beta-proteins in soft-shelled and hard-shelled turtles produced during the process of epidermal differentiation. | the tough corneous layer in the carapace and plastron of hard-shelled turtles derives from the accumulation of keratin-associated beta-proteins (kabetaps, formerly called beta-keratins) while these proteins are believed to be absent in soft-shelled turtles. our bioinformatics and molecular study has instead shown that the epidermis of the soft-shelled turtle apalone spinifera expresses beta-proteins like or even in higher amount than in the hard-shelled turtle pseudemys nelsoni. the analysis of ... | 2013 | 23794440 |
| evidence of steroid hormone activity in the chorioallantoic membrane of a turtle (pseudemys nelsoni). | endocrine properties of extraembryonic membranes have traditionally been viewed as a characteristic of placental amniotes. however, our laboratory recently demonstrated that this ability extends to the extraembryonic membranes of two oviparous amniotes (chicken and alligator) indicating that endocrine extraembryonic membranes are not an innovation of placental amniotes and suggesting that this could be a shared amniote characteristic. in this study, we test our hypothesis that the chorioallantoi ... | 2013 | 23458289 |
| a new polystomatid (monogenea, polystomatidae) from the mouth of the north american freshwater turtle pseudemys nelsoni. | based on material collected from pseudemys nelsoni (reptilia: chelonia: emydidae) during a parasite survey of the herpetofauna around gainesville, florida, usa, polystomoides nelsoni sp. n. is described as a new polystome species. this parasite was found in the oral and pharyngeal region of the host. in a sample of nine pseudemys nelsoni, three specimens were found to release polystome eggs. one turtle was euthanized and dissected and found to be infected in the oral region with 19 specimens bel ... | 2015 | 26798243 |
| long-term retention of visual tasks by two species of emydid turtles, pseudemys nelsoni and trachemys scripta. | long-lived species are expected to have long-term memory capabilities. in this study we tested nine florida red-bellied cooters (pseudemys nelsoni) on their retention for both a procedural food acquisition task and visual discrimination task learned in a previous experiment. the turtles were tested and retrained after two months, after another 7.5 months, and finally after 36 months of no interaction with the test apparatus during the intervening periods. turtles retained memory for the choice t ... | 2012 | 22582817 |
| turtles (pseudemys nelsoni) learn about visual cues indicating food from experienced turtles. | we investigated whether turtles (pseudemys nelsoni) could learn about a visual object cue to obtain food reinforcement by observing conspecifics that had learned the task. this study was designed with a three part task which, if completed by the observer turtles, would provide evidence of their abilities to learn from other turtles using stimulus enhancement, goal emulation, or copying. all four p. nelsoni turtles tested after observation of a trained demonstrator, whom they had direct access to ... | 2011 | 21842979 |
| harderian gland adenocarcinoma in a florida red-bellied turtle ( pseudemys nelsoni ) - case report. | the authors describe a case of unilateral adenocarcinoma emerging from the harderian gland, filling the right orbital cavity of a florida red-bellied turtle ( pseudemys nelsoni ). the tumour did not produce any metastasis but presented an expansive growth and led to the dislocation and protrusion of the right eyeball. histopathological analysis revealed the presence of numerous mitotic figures in the cellular population that made up the tumour. the tumour cells completely filled the alveoli of t ... | 2009 | 19584040 |
| training and long-term memory of a novel food acquisition task in a turtle (pseudemys nelsoni). | we developed a shaping procedure for training florida red-bellied cooters, pseudemys nelsoni, to dislodge clear plastic bottles to obtain food pellets. the animals were then trained in a 2-choice problem to choose only the bottle containing pellets. all nine turtles learned the task of knocking over bottles for food. for the discrimination task, turtles chose the correct bottle 71% on average. after 2 months (82-84 days), and again after another 7.5 months (228 days) of no interaction with the b ... | 2007 | 17433570 |
| physiological effects of hypoxia on metabolism and growth of turtle embryos. | hypoxic effects on embryonic metabolism and growth of florida red-bellied turtle (pseudemys nelsoni) embryos were studied. eggs were assigned to either normoxic (21% o2) or hypoxic (10% o2) treatment on day 21. oxygen consumption (vo2) and embryonic mass were measured periodically. on day 21 and 33, critical oxygen tension (pc) of embryos and morphometry of blood vessels in chorioallantoic membranes were measured. although embryos exposed to normoxia increased vo2 and mass at a rate greater than ... | 1993 | 8327786 |