The hippocampus of birds and mammals has been shown to play a crucial role in spatial memory and navigation. The hippocampus exhibits plasticity in adulthood in response to diverse environmental factors associated with spatial demands placed on an animal. The cortical telencephalon of squamate reptiles has been implicated as a functional homologue to the hippocampus. This study sought to experimentally manipulate the navigational demands placed on free-ranging northern Pacific rattlesnakes (Crotalus o. oreganus) to provide direct evidence of the relationship between spatial demands and neuroplasticity in the cortical telencephalon of the squamate brain. Adult male rattlesnakes were radio-tracked for two months, during which one of three treatments was imposed weekly: 225 meter translocation in a random direction, 225 meter walk and release at that day’s capture site (handling control), and undisturbed control. Snakes were then sacrificed and brains were removed and processed for histological analysis of cortical features. The volume of the medial cortex was significantly larger in the translocated group compared to undisturbed controls. No differences in dorsal or lateral cortical volume were detected among the groups. Numbers of 5-Bromo-2’-deoxyuridine (BrdU) -labeled cells in the medial and dorsal cortices three weeks after BrdU injection were not affected by treatment. The activity range was larger in the translocated group compared to handled and undisturbed controls. A causal relationship between increased navigation in a free-ranging reptile and changes in brain morphology was established. The use of translocation as a conservation strategy for reptiles is a controversial topic revisited many times. Previous studies have demonstrated the aberrant movement patterns and mortality caused by translocation and have established that short-distance translocation within an animal’s home range is best for the animal. In conjunction with the neuroplasticity study, we examined the physiological impacts that repeated short-distance translocation and handling have on reptiles. This is essential knowledge if the efficacy of the technique is to be properly evaluated. Baseline and stressed concentrations of corticosterone and testosterone were assayed in blood taken immediately upon capture and following one hour of confinement in a bucket. Neither baseline nor stressed concentrations of either hormone were impacted by translocation or handling. Body condition and change in mass were not affected. Translocated animals had larger MCP activity ranges than handled and undisturbed animals at the 95%, but not 100% levels, while an interaction between time and treatment impacted other movement parameters.Treatment had no effect on a number of behaviors observed during visits to each animal. We suggest that rattlesnakes are quite resistant to potential impacts on their physiology and behavior enacted by frequent short-distance translocation or handling. Additionally, studies that require frequent handling of reptilian subjects are not likely to severely alter stress physiology.

No description available.

Eighteen prairie rattlesnakes (Crotalus viridis viridis) were tracked using radio-telemetry and 82 snakes were PIT-tagged over a 2-year period in Lethbridge, AB to determine population size, movement patterns, and habitat utilization, and to predict fragmentation effects on the species within an urban locale. Population size was estimated using closed population models at 374 snakes (295 adults) and open population models at 204 snakes (161 adults), greater than an estimate of <50 adults in 2003 (Ernst, 2003) and 2006 (Ernst & Quinlan, 2006). Mean home range sizes, based on 95% minimum convex polygon analysis, differed significantly between years (31.51 ha in 2005, 3.72 ha in 2006). Calculated movement parameters, such as mean distance moved per day, total distance moved over the course of the active season, and frequency of movement varied between years and individuals. Greater-than-expected (under hypotheses of even habitat choice) utilization was observed in habitat types located within coulee and flood plain areas, with apparent preference towards unbroken parcels of grassland or cottonwoods, whereas less-than-predicted utilization of agricultural habitat type was observed. Fragmentation effects on prairie rattlesnake movement and occurrence were examined through modeling and were found to coincide with observed species’ locations, suggesting that prairie rattlesnakes are undergoing modification of movement patterns to avoid highly concentrated human density or use. Influence of weather on the use of vegetative ground cover was observed, as it was accessed more by prairie rattlesnakes at higher temperatures. Recommendations towards future management of the prairie rattlesnake population in Lethbridge are given, including protection of the Bridge View Drive site and inclusion of varied habitat types and terrain when planning habitat and wildlife corridors. Management decisions that ensure remaining habitat parcels and connective areas near rattlesnake foraging or movement corridors are also advocated. Identification of future research focuses include studies on juvenile survivorship, genetic structure, and vehicle-related mortality. / xii, 83 leaves : col. ill., col. maps ; 29 cm

Class of 2012 Abstract / Specific Aims: Determine the difference in venom potency among Mohave Rattlesnakes in Cochise in Pima Counties and determine if those differences correlate to changes in clinical outcomes. Methods: Twenty-one Mohave rattlesnakes, C. s. scutulatus were collected from Arizona and New Mexico. Venom proteomes were analyzed using RP-HPLC and SDS-PAGE. The toxicity of venoms was analyzed using LD50. Health severity outcomes between two Arizona counties, Pima and Cochise, were determined by retrospective chart review of the Arizona Poison and Drug Information Center database between 2002-2009. Main Results: Six phenotypes were identified based on three venom proteins; Mojave toxin, SVMP PI and PIII, and myotoxin. Venom changed geographically from SVMP-rich to Mojave toxin-rich phenotypes from south central to southeastern Arizona. Phenotypes containing myotoxins were only found in the transitional zone between the SVMP and Mojave toxin phenotypes. Venom samples containing the largest amounts of SVMP or Mojave toxin had highest and lowest LD50s, respectively. Conclusions: There was a significant difference when comparing the presence of CNS affects between Pima and Cochise counties (p = 0.001). No significant difference was found when comparing severity number of antivenom vials administered, days spent in a health care facility or envenomation per 100,000 population. Although not part of the original data to be collected, death and intubations, were also noted. There is a 10x and 50x increased risk of death or intubations if envenomated in Cochise County.

A serpente Crotalus durissus , popularmente conhecida como cascavel, pertence à família Viperidae, e como a maioria dos viperídeos, é uma espécie vivípara. Este estudo teve como objetivo descrever a histologia do oviduto de fêmeas adultas e do saco vitelino e cordão umbilical de fetos em estágios gestacionais avançados de Crotalus durissus . A placenta de Crotalus durissus é constituída pela aposição do epitélio de revestimento do oviduto com a membrana corio-alantoidina que recobre o hemisfério embrionário do ovo. Estas se interdigitam sutilmente e separando a membrana corio-alantoidinana e o revestimento do oviduto está um remanescente da casca do ovo, chamada de membrana da casca. Quando avaliada a distribuição das fibras do sistema colágeno na placenta corio-alantoidina observamos que as fibras se distribuem irregularmente formando arcabouços de sustentação para os vasos e conferindo maior resistência nas regiões próximas a superfície logo abaixo do epitélio coriônico. Em estágios avançados de gestação, a parede do oviduto de Crotalus durissus apresenta-se como uma estrutura delgada, composta por um epitélio com células cuboidais, repousando em uma lâmina própria constituída por tecido conjuntivo. A mucosa do oviduto de Crotalus durissus apresenta regiões com projeções semelhantes à vilos, sustentados por eixos de fibras colágenas. Em estágios avançados de gestação, a face voltada para o feto do saco vitelino está revestida por um epitélio de células colunares grandes com núcleo posicionado basalmente, apresentando grânulos eosinófilicos. O conteúdo vitelino é, basicamente, constituído por depósitos celulares ricos em proteína e muito eosinofílicos. A distribuição do vitelo parece apresentar uma organização em forma de cachos de uvas sendo os ramos constituídos por trabéculas de células que trazem consigo vasos sanguíneos. Em Crotalus durissus , o cordão umbilical promove a conexão entre os tecidos maternos e os fetos, sendo uma estrutura ricamente vascularizada, constituído por duas artérias e uma veia e o ducto alantoide, envoltos por um tecido mucoide (mesenquimal) / The snake Crotalus durissus, popularly known as rattlesnake, belongs to the family Viperidae, and like most viperids, is a viviparous species. This study aimed to describe the oviduct histology of adult females and yolk sac and umbilical cord of fetuses in advanced stages of pregnancy in Crotalus durissus. The Crotalus durissus placenta is formed by affixing the oviduct epithelium lining with chorio-alantoidina membrane covering the embryonic hemisphere of the \"egg\". These interdigitate subtly and separating the chorioalantoidinana membrane and the oviduct of the coating is one of the eggshell remnant, called the shell membrane. When evaluated the distribution of collagen fibers in the system chorio-alantoidina placenta observed that the fibers forming irregularly distributed support frameworks for vessels and providing greater resistance in the regions near the surface just below the chorionic epithelium. In advanced stages of pregnancy, the wall of the oviduct in Crotalus durissus appears as a thin structure made up of a cuboidal epithelium with cells, resting on a lamina consists of connective tissue. The mucosa of the oviduct of Crotalus durissus presents regions with projections similar to the villi, supported by shafts of collagen fibers. In advanced stages of pregnancy, the fetus side facing the yolk sac is coated by a large columnar epithelial cells with basally placed core, with eosinophilic granules. The yolk contents basically comprised of cellular rich protein deposits, and eosinophilic. The distribution of the calf seems to present an organization in a \"bunch of grapes\" being the groups consisting of trabecular cells bring with blood vessels. In Crotalus durissus, the umbilical cord promotes the connection between fetal and maternal tissues and is a highly vascularized structure, consisting of two arteries and one vein, and the allantoic duct, surrounded by a mucoid tissue (mesenchymal)

A serpente Crotalus durissus , popularmente conhecida como cascavel, pertence à família Viperidae, e como a maioria dos viperídeos, é uma espécie vivípara. Este estudo teve como objetivo descrever a histologia do oviduto de fêmeas adultas e do saco vitelino e cordão umbilical de fetos em estágios gestacionais avançados de Crotalus durissus . A placenta de Crotalus durissus é constituída pela aposição do epitélio de revestimento do oviduto com a membrana corio-alantoidina que recobre o hemisfério embrionário do ovo. Estas se interdigitam sutilmente e separando a membrana corio-alantoidinana e o revestimento do oviduto está um remanescente da casca do ovo, chamada de membrana da casca. Quando avaliada a distribuição das fibras do sistema colágeno na placenta corio-alantoidina observamos que as fibras se distribuem irregularmente formando arcabouços de sustentação para os vasos e conferindo maior resistência nas regiões próximas a superfície logo abaixo do epitélio coriônico. Em estágios avançados de gestação, a parede do oviduto de Crotalus durissus apresenta-se como uma estrutura delgada, composta por um epitélio com células cuboidais, repousando em uma lâmina própria constituída por tecido conjuntivo. A mucosa do oviduto de Crotalus durissus apresenta regiões com projeções semelhantes à vilos, sustentados por eixos de fibras colágenas. Em estágios avançados de gestação, a face voltada para o feto do saco vitelino está revestida por um epitélio de células colunares grandes com núcleo posicionado basalmente, apresentando grânulos eosinófilicos. O conteúdo vitelino é, basicamente, constituído por depósitos celulares ricos em proteína e muito eosinofílicos. A distribuição do vitelo parece apresentar uma organização em forma de cachos de uvas sendo os ramos constituídos por trabéculas de células que trazem consigo vasos sanguíneos. Em Crotalus durissus , o cordão umbilical promove a conexão entre os tecidos maternos e os fetos, sendo uma estrutura ricamente vascularizada, constituído por duas artérias e uma veia e o ducto alantoide, envoltos por um tecido mucoide (mesenquimal) / The snake Crotalus durissus, popularly known as rattlesnake, belongs to the family Viperidae, and like most viperids, is a viviparous species. This study aimed to describe the oviduct histology of adult females and yolk sac and umbilical cord of fetuses in advanced stages of pregnancy in Crotalus durissus. The Crotalus durissus placenta is formed by affixing the oviduct epithelium lining with chorio-alantoidina membrane covering the embryonic hemisphere of the \"egg\". These interdigitate subtly and separating the chorioalantoidinana membrane and the oviduct of the coating is one of the eggshell remnant, called the shell membrane. When evaluated the distribution of collagen fibers in the system chorio-alantoidina placenta observed that the fibers forming irregularly distributed support frameworks for vessels and providing greater resistance in the regions near the surface just below the chorionic epithelium. In advanced stages of pregnancy, the wall of the oviduct in Crotalus durissus appears as a thin structure made up of a cuboidal epithelium with cells, resting on a lamina consists of connective tissue. The mucosa of the oviduct of Crotalus durissus presents regions with projections similar to the villi, supported by shafts of collagen fibers. In advanced stages of pregnancy, the fetus side facing the yolk sac is coated by a large columnar epithelial cells with basally placed core, with eosinophilic granules. The yolk contents basically comprised of cellular rich protein deposits, and eosinophilic. The distribution of the calf seems to present an organization in a \"bunch of grapes\" being the groups consisting of trabecular cells bring with blood vessels. In Crotalus durissus, the umbilical cord promotes the connection between fetal and maternal tissues and is a highly vascularized structure, consisting of two arteries and one vein, and the allantoic duct, surrounded by a mucoid tissue (mesenchymal)

Class of 2012 Abstract / Specific Aims: Determine the difference in venom potency among Mohave Rattlesnakes in Cochise in Pima Counties and determine if those differences correlate to changes in clinical outcomes. Methods: Twenty-one Mohave rattlesnakes, C. s. scutulatus were collected from Arizona and New Mexico. Venom proteomes were analyzed using RP-HPLC and SDS-PAGE. The toxicity of venoms was analyzed using LD50. Health severity outcomes between two Arizona counties, Pima and Cochise, were determined by retrospective chart review of the Arizona Poison and Drug Information Center database between 2002-2009. Main Results: Six phenotypes were identified based on three venom proteins; Mojave toxin, SVMP PI and PIII, and myotoxin. Venom changed geographically from SVMP-rich to Mojave toxin-rich phenotypes from south central to southeastern Arizona. Phenotypes containing myotoxins were only found in the transitional zone between the SVMP and Mojave toxin phenotypes. Venom samples containing the largest amounts of SVMP or Mojave toxin had highest and lowest LD50s, respectively. Conclusions: There was a significant difference when comparing the presence of CNS affects between Pima and Cochise counties (p = 0.001). No significant difference was found when comparing severity number of antivenom vials administered, days spent in a health care facility or envenomation per 100,000 population. Although not part of the original data to be collected, death and intubations, were also noted. There is a 10x and 50x increased risk of death or intubations if envenomated in Cochise County.

Na cascavel Crotalus durissus terrificus ocorre o armazenamento de longo prazo do esperma (LTSS), no trato genital da fêmea, durante o intervalo entre a cópula (outono) e a ovulação (primavera). Peptídeos e peptidases estão entre os principais componentes que influenciam a atividade espermática em mamíferos. O presente estudo objetivou caracterizar a presença de peptidases em C. d. terrificus, com esta função reconhecida em mamíferos e/ou que clivam peptídeos atuantes nesta função, bem como avaliar a hipótese do envolvimento destas peptidases na preservação dos espermatozóides desta serpente. O aspecto morfo-funcional dos espermatozóides foi comparado na presença dos peptídeos angiotensina II (AngII), arginina vasotocina (AVT), bradicinina (BK), peptídeo promotor da fecundação (FPP) e hormônio liberador de tireotrofina (TRH). Caracterizamos os efeitos de agentes quelante, tiol-redutor, cofator e inibidores, bem como dos peptídeos supracitados, sobre as atividades enzimáticas relacionadas, quais sejam: aminopeptidases ácida (APA), básica (APB), alanil sensível (APN-PS) e insensível à puromicina (APN-PI), cistil (CAP), dipeptidil-peptidase IV (DPPIV), piroglutamil tipo 1 (PAP-I) e prolil-imino- (PIP), bem como da prolil endopeptidase (POP), em frações solúvel (FS) e/ou de membrana solubilizada (FM) do sêmen proveniente do ducto deferente, assim como deste próprio tecido e dos tecidos uterino e vaginal de C. d. terrificus, ou seja, tecidos por onde passam ou armazenam-se os espermatozóides. Verificamos a variação sazonal destas mesmas atividades, nestes tecidos, incluindo o sêmen armazenado no útero durante o LTSS. O sêmen coletado do ducto deferente foi fracionado para avaliação da distribuição destas atividades peptidásicas. Nossos dados mostraram características de liquefação do sêmen e movimento dos espermatozóides da cascavel que os diferenciam do padrão humano. FPP com cálcio e BK melhoraram a preservação da viabilidade espermática, similarmente ao que ocorre em mamíferos. Em todos os tecidos e no sêmen as atividades APB, PIP e POP foram detectadas apenas da FS, enquanto as demais estão presentes em FS e FM, seguindo um padrão de distribuição observado na maioria dos tecidos de mamíferos. Amastatina e bestatina inibiram APB e APN, enquanto a diprotina A foi o inibidor mais eficiente para a DPPIV em FM. PAP-I e PIP foram inibidas, respectivamente, por bestatina e puromicina. Este perfil de inibição também é similar ao encontrado para as aminopeptidases em tecidos de mamíferos. Todas as atividades peptidásicas foram influenciadas por algum dos peptídeos estudados, sugerindo que tais peptídeos são substratos potenciais e/ou moduladores destas atividades na cascavel. As atividades APB e APN foram caracterizadas como metalopeptidases. APB, CAP e DPPIV foram inibidas por MnCl2. CAP e PAP-I foram caracterizadas como enzimas sulfidril-dependentes. As atividades APB, APN-PI e APN-PS predominaram, em relação às demais peptidases, em todas as estações e na maioria dos tecidos e no sêmen, sugerindo sua maior relevância na fisiologia reprodutiva da C. d. terrificus. Os níveis de todas as atividades peptidásicas estudadas variaram sazonalmente, sugerindo que sua ação moduladora sobre peptídeos susceptíveis está integrada ao ciclo reprodutivo desta serpente. O fracionamento do sêmen do ducto deferente revelou a presença de fluido seminal e espermatozóides, bem como de uma estrutura prostassoma-símile, até então somente identificada em mamíferos. Em todas estas frações há atividade peptidásica, predominando a APN-PI no prostassoma-símile e no fluido seminal, e APN-PS e APN-PI na FS e FM dos espermatozóides, caracterizando um envolvimento com a redução da motilidade espermática, tal qual ocorre em mamíferos. Concluimos que as atividades peptidásicas estudadas apresentam características sazonais e tecido-específicas que sugerem uma atuação relevante na preservação dos espermatozóides de C.d. terrificus. / In the rattlesnake Crotalus durissus terrificus occurs the long-term sperm storage (LTSS), in the female tract, during the interval between mating (autumn) and ovulation (spring). Peptides and peptidases are among the main components that influence the spermatic activity in mammals. The present study aimed to characterize the presence of peptidases in C. d. terrificus, that are well-recognized to exert this function and/or that have the ability to hydrolyze peptides that exert this function in mammals, as well to evaluate whether these peptidases are related to the preservation of spermatozoids in this snake. The morphological and functional characteristics of spermatozoids were compared in the presence of angiotensin II (AngII), arginine-vasotocin (AVT), bradykinin (BK), fertilization promoting peptide (FPP) and thyrotropin-releasing hormone (TRH). We have checked the effect of chelating and thiol-reducing agents, cofactor and inhibitors, as well the effect of aforementionated peptides on related enzyme activities such as acid (APA), basic (APB), puromycin-sensitive (APN-PS) and puromycin-insensitive alanyl (APN-PI), cystyl (CAP), pyroglutamyl type 1 (PAP-I) and prolyl-imino (PIP) aminopeptidases, and dipeptidyl-peptidase IV (DPPIV), as well as on prolyl endopeptidase (POP), in soluble (FS) and/or solubilized membrane-bound (FM) fractions of semen from vas deferens, of this own tissue, and vagina and uterus tissues of C. d. terrificus, i.e. tissues where spermatozoids pass through or where they are stored. The seasonal variation of these peptidase activities, in all tissues, including the semen stored in uterus during the LTSS, were evaluated. The semen from vas deferens was fractioned in order to know the distribution of these peptidase activities. The features of seminal liquefaction and movement of spermatozoids were different between the rattlesnake and human. Similar to mammals, FPP plus calcium and BK improved the preservation of the viability of spermatozoids from C. d. terrificus. In all tissues and semen, the APB, PIP and POP activities were detected only in FS, while others peptidases were present in FS and FM, following a similar pattern of distribution usually observed in mammalian tissues. Amastatin and bestatin inhibited APB and APN activities, while diprotin A was the most efficient inhibitor of DPPIV in FM. PAP-I and PIP activities were inhibited by bestatin and puromycin, respectively. This inhibition profile was similar to that of mammalian tissues. All peptidase activities were influenced at least by one of the peptides under study, suggesting these peptides as potential substrates and/or modulators for these peptidases of the rattlesnake. The APB and APN activities were characterized as metallopeptidases. APB, CAP and DPPIV were inhibited by MnCl2. CAP and PAP-I were characterized as sulfhydryl-dependent enzymes. The APB, APN-PI and APN-PS activities were predominant, in relation to the other examined peptidases, in all seasons and in most tissues and semen, suggesting their great relevance in the reproductive physiology of the C. d. terrificus. The levels of all studied peptidase activities were seasonally variable, suggesting that their modulator actions on susceptible peptides are integrated to the reproductive cycle of this snake. The fractionation of C. d. terrificus semen revealed the presence of seminal fluid and spermatozoids, as well a prostasome-like structure, until then identified only in mammals. In all of these fractions, there are peptidase activities, predominating the APN-PI in prostasome and seminal fluid, and the APN-PS and APN-PI in FS and FM of spermatozoids, suggesting their involvement in the reduction of the spermatic mobility, such as in mammals. In conclusion, the studied peptidase activities present seasonal and tissue-specific characteristics, which suggest a relevant role in the preservation of the spermatozoids of C. d. terrificus.

I combined long-term ecological data and population genetic data using microsatellite DNA markers to examine among- and within-population genetic structure and parentage in Tiger Rattlesnake (Crotalus tigris) populations from the Tucson Basin of southern Arizona located in the northern Sonoran Desert. Based on long-term data from radio telemetry, I determined that C. tigris show strong fidelity to both their home range and winter shelter sites, remaining in close proximity to rocky habitats within mountain ranges, which leads to apparent natural isolation of populations. Therefore, I predicted that C. tigris populations would show substantial genetic differentiation among mountain ranges. However, Bayesian clustering analyses revealed a surprising pattern of extensive admixture among mountain ranges, indicating the presence of gene flow among populations. This pattern of genetic admixture can likely be explained by historical changes in climate and physiognomy in the Sonoran Desert. Analyses of pack rat midden remains clearly show that mountain ranges were previously connected by mesic woodland habitats that may have led to panmixia in C. tigris populations as recently as 5,000-8,000 years ago. At present, C. tigris show a strong preference for xeroriparian washes, which allows individuals to occasionally move relatively long distances, likely resulting in contemporary gene flow. To maintain connections among mountain ranges, I recommend effective management, protection, and restoration (if needed) of wash habitats, which also act as corridors for a suite of other species. At the within population scale, genetic clustering analyses revealed the existence of fine-scale genetic structure in C. tigris subpopulations located in the Rincon Mountains. Further analyses based on location data of individuals indicated the existence of a potential barrier to gene flow, which corresponded to a watershed divide. Although the watershed divide would appear not to present a physical barrier to gene flow, it likely acts to segregate populations based on habitat and movement preferences associated with wash habitats. Data on spatial ecology and reproductive behavior, indicate that C. tigris distribute gametes across the landscape in the absence of actual displacement of individuals due to fidelity to home ranges and winter shelter sites. Analyses of parentage were constrained by the difficulty in obtaining offspring from gravid female C. tigris that give birth deep in rock outcrops. However, I did conduct analyses on over 30 offspring from known mothers and nearly 60 free-ranging offspring found while conducting ecological research. Surprisingly, not a single male C. tigris found courting or copulating with a female was identified as the father, indicating that reproductive behavior is a poor predictor of parentage, and therefore, fitness. Interestingly, males identified as fathers were found up to 2 km distance from their offspring, demonstrating that males from surrounding areas may move relatively long distances to mate. The mating system of C. tigris, which is characterized by promiscuity in both sexes, appears to drive dramatic differences in spatial ecology between males and females, and may lead to fine-scale genetic structure among females and not males who spend a great deal of time searching for receptive females.

The selective use of habitat is a fundamental aspect of ecology, and differential patterns of habitat use reflect the underlying cues that guide selection. I assessed the habitat use and movement patterns of Northern Pacific Rattlesnakes (Crotalus o. oreganus) during the summers of 2005 and 2006 near Kamloops British Columbia, Canada. Contrary to my expectations, rattlesnakes used upper - elevation forested habitat when available and traveled farther from the den than previously reported for this species. Though the distance and orientation of travel differed among individuals, there was an apparent trend for snakes from one site to travel farther from the den than snakes from a second site. Snakes often were associated with structurally stable cover objects and small mammal sign in microhabitats with less canopy cover than otherwise available. Results from this study have implications for management and conservation of the Northern Pacific Rattlesnake.