| selected regulation of gastrointestinal acid-base secretion and tissue metabolism for the diamondback water snake and burmese python. | snakes exhibit an apparent dichotomy in the regulation of gastrointestinal (gi) performance with feeding and fasting; frequently feeding species modestly regulate intestinal function whereas infrequently feeding species rapidly upregulate and downregulate intestinal function with the start and completion of each meal, respectively. the downregulatory response with fasting for infrequently feeding snakes is hypothesized to be a selective attribute that reduces energy expenditure between meals. to ... | 2012 | 22162867 |
| mutations to the cardiotonic steroid binding site of na(+)/k(+)-atpase are associated with high level of resistance to gamabufotalin in a natricine snake. | although toads are defended by bufadienolide toxins, some snakes have evolved resistance to bufadienolides and feed heavily on toads. we compared resistance in nerodia rhombifer, which possesses mutations that confer target-site resistance, to pituophis catenifer, which lacks those mutations. even at the highest dosage tested, nerodia showed no effects, whereas the lowest dose was lethal to pituophis. our results demonstrate a striking level of resistance to bufadienolides in a species possessin ... | 2016 | 26905927 |
| ontogenetic shifts and spatial associations in organ positions for snakes. | snakes possess an elongated body form and serial placement of organs which provides the opportunity to explore historic and adaptive mechanisms of organ position. we examined the influence of body size and sex on the position of, and spatial associations between, the heart, liver, small intestine, and right kidney for ten phylogenetically diverse species of snakes that vary in body shape and habitat. snake snout-vent length explained much of the variation in the position of these four organs. fo ... | 2015 | 26358987 |
| a test of energetic trade-offs between growth and immune function in watersnakes. | energy budgets explain how organisms allocate energetic intake to accomplish essential processes. a likely life history trade-off occurs between growth and immune response in juvenile organisms, where growth is important to avoid predation or obtain larger prey and immune response is essential to survival in the presence of environmental pathogens. we examined the innate (wound healing) and adaptive (lymphoid tissue, thymus and spleen) components of immune response along with growth in two popul ... | 2015 | 26062440 |
| characterization of carbonic anhydrase xiii in the erythrocytes of the burmese python, python molurus bivittatus. | carbonic anhydrase (ca) is one of the most abundant proteins found in vertebrate erythrocytes with the majority of species expressing a low activity ca i and high activity ca ii. however, several phylogenetic gaps remain in our understanding of the expansion of cytoplasmic ca in vertebrate erythrocytes. in particular, very little is known about isoforms from reptiles. the current study sought to characterize the erythrocyte isoforms from two squamate species, python molurus and nerodia rhombifer ... | 2015 | 26005204 |
| effects of feeding on luminal ph and morphology of the gastroesophageal junction of snakes. | at the gastroesophageal junction, most vertebrates possess a functional lower esophageal sphincter (les) which may serve to regulate the passage of liquids and food into the stomach and prevent the reflux of gastric contents into the esophagus. snakes seemingly lack an les and consume meals large enough to extend anteriorly from the stomach into the esophagus thereby providing the opportunity for the reflux of gastric juices. to explore whether snakes experience or can prevent gastric reflux, we ... | 2012 | 22938694 |
| does dispersal across an aquatic geographic barrier obscure phylogeographic structure in the diamond-backed watersnake (nerodia rhombifer)? | the impact of barriers to dispersal and gene flow is often inferred to be the primary cause of lineage divergence and phylogeographic structure in terrestrial organisms. in particular, the mississippi river has been implicated as a barrier to gene flow in many species, including aquatic taxa. however, if barriers are permeable to organisms, then phylogeographic structure may be difficult to detect due to gene flow between lineages. using time-calibrated bayesian phylogenetic analyses of mtdna, a ... | 2010 | 20688180 |
| integrated postprandial responses of the diamondback water snake, nerodia rhombifer. | among snakes, the magnitude to which intestinal performance is regulated with feeding and fasting is adaptively linked to their natural feeding frequency. for infrequently feeding boas and pythons, gastrointestinal form and function are widely regulated with each feeding bout. in contrast, snakes that naturally feed more frequently modestly regulate intestinal function with each meal. to further explore the postprandial responses of a frequently feeding snake and assess whether such responses ar ... | 2010 | 20438359 |
| intraspecific differences in thermal tolerance of the diamondback watersnake (nerodia rhombifer): effects of ontogeny, latitude, and sex. | ontogenetic shifts in microhabitat use are widespread among taxa and can result in drastic shifts in thermal habitat among age classes. likewise, geographic variation in climate along latitudinal gradients can cause differences in thermal environments among populations of a species. using a common garden design, we examined four populations of a single species of semi-aquatic snake, nerodia rhombifer, to determine whether ontogenetic shifts in habitat use (and/or body size) and latitudinal diffe ... | 2005 | 15664323 |
| differential swimming performance of two natricine snakes exposed to a cholinesterase-inhibiting pesticide. | environmental contaminants have direct effects on organisms at the molecular, cellular, and tissue levels, but the net results of these sub-organismal effects are only consequential to exposed populations if they alter organism-level traits that ultimately influence fitness (e.g., growth, locomotor performance, reproduction, and survival). here, we explore the possibility that the swimming performance of neonate black swamp snakes (seminatrix pygaea) and diamondback water snakes (nerodia rhombif ... | 2005 | 15519728 |
| non-invasive measure of body composition of snakes using dual-energy x-ray absorptiometry. | non-invasive techniques to measure body composition are critical for longitudinal studies of energetics and life histories and for investigating the link between body condition and physiology. previous attempts to determine, non-invasively, the body composition of snakes have proven problematic. therefore, we explored whether dual-energy x-ray absorptiometry (dxa) could be used to determine the body composition of snakes. we analyzed 20 adult diamondback water snakes (nerodia rhombifer) with a d ... | 2003 | 14511756 |
| sweeping and striking: a kinematic study of the trunk during prey capture in three thamnophiine snakes. | the trunk plays an obvious and important role in the prey capture behavior of many species of snake, yet trunk function during predatory strikes is poorly understood. axial kinematics of three thamnophiine snakes (thamnophis couchii, thamnophis elegans and nerodia rhombifer) were studied to quantify differences between sideways-directed and forward-directed attacks and to investigate strike diversity at relatively low phylogenetic levels. feeding strikes were filmed at 60 hz, and 13 points along ... | 2003 | 12796455 |
| development of antipredator responses in snakes: v. species differences in ontogenetic trajectories. | the ontogeny of antipredator responses in five species of natricine snakes was examined. in a split-litter experiment, neonates were given a standardized defensive behavior test at 1 and/or 20 days of age. thamnophis sirtalis and thamnophis melanogaster showed a significant increase in both striking and fleeing from a threatening stimulus. thamnophis butleri was not reactive in terms of striking at either age but did flee frequently at both ages. thamnophis radix showed low rates of striking and ... | 1992 | 1618371 |
| role of phenotypic plasticity in morphological differentiation between watersnake populations. | an individual's morphology is shaped by the environmental pressures it experiences, and the resulting morphological response is the culmination of both genetic factors and environmental (non-genetic) conditions experienced early in its life (i.e. phenotypic plasticity). the role that phenotypic plasticity plays in shaping phenotypes is important, but evidence for its influence is often mixed. we exposed female neonate diamond-backed watersnakes (nerodia rhombifer) from populations experiencing d ... | 2020 | 31912622 |