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Andrew J Pask - One of the best experts on this subject based on the ideXlab platform.
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formation of 5α reduced androgens in the testes and urogenital tract of the grey short tailed Opossum monodelphis domestica
Reproduction Fertility and Development, 2009Co-Authors: Richard J Auchus, Andrew J PaskAbstract:Testicular 5α-reduced androgens, largely 5α-androstane-3α,17β-diol (androstanediol), are responsible for virilisation of pouch young in one marsupial (the tammar wallaby), but are not formed until later in development in another marsupial (the brushtail possum) and in rodents. Because the mechanism of virilisation of the urogenital tract in the grey short-tailed Opossum Monodelphis domestica has never been defined, androgen formation and metabolism were investigated in this species. Testis fragments from grey short-tailed Opossums of a wide range of ages were incubated with ( 3 H)-progesterone and the metabolites were separated by high-performance liquid chromatography (HPLC). The only 19-carbon metabolites identified in the youngest ages (5-26 days) and the major metabolites in adult testes were testosterone and androstenedione. At 30, 42 and 49 days of age, dihydrotestosterone and small amounts of androstanediol were present. Time-sequence studies indicated that dihydrotestosterone and androstanediol were formed from the 5α-reduction (and 3-keto reduction) of testosterone. In a second series of experiments, tissue fragments of a variety of urogenital tract tissues were incubated with ( 3 H)-testosterone and the metabolites separated by HPLC. During the interval in which male urogenital tract differentiation takes place in this species (between Days 15 and 28), the major metabolite identified was dihydrotestosterone. We conclude that the timing of 5α-reductase expression in the testes of the grey short-tailed possum resembles that of rodents and the brushtail possum rather than that of the tammar wallaby and that dihydrotestosterone is probably the intracellular androgen responsible for virilisation of the urogenital tract in this species.
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formation of 5α reduced androgens in the testes and urogenital tract of the grey short tailed Opossum monodelphis domestica
Reproduction Fertility and Development, 2009Co-Authors: Richard J Auchus, Andrew J PaskAbstract:Testicular 5alpha-reduced androgens, largely 5alpha-androstane-3alpha,17beta-diol (androstanediol), are responsible for virilisation of pouch young in one marsupial (the tammar wallaby), but are not formed until later in development in another marsupial (the brushtail possum) and in rodents. Because the mechanism of virilisation of the urogenital tract in the grey short-tailed Opossum Monodelphis domestica has never been defined, androgen formation and metabolism were investigated in this species. Testis fragments from grey short-tailed Opossums of a wide range of ages were incubated with [3H]-progesterone and the metabolites were separated by high-performance liquid chromatography (HPLC). The only 19-carbon metabolites identified in the youngest ages (5-26 days) and the major metabolites in adult testes were testosterone and androstenedione. At 30, 42 and 49 days of age, dihydrotestosterone and small amounts of androstanediol were present. Time-sequence studies indicated that dihydrotestosterone and androstanediol were formed from the 5alpha-reduction (and 3-keto reduction) of testosterone. In a second series of experiments, tissue fragments of a variety of urogenital tract tissues were incubated with [3H]-testosterone and the metabolites separated by HPLC. During the interval in which male urogenital tract differentiation takes place in this species (between Days 15 and 28), the major metabolite identified was dihydrotestosterone. We conclude that the timing of 5alpha-reductase expression in the testes of the grey short-tailed possum resembles that of rodents and the brushtail possum rather than that of the tammar wallaby and that dihydrotestosterone is probably the intracellular androgen responsible for virilisation of the urogenital tract in this species.
Leah Krubitzer - One of the best experts on this subject based on the ideXlab platform.
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photic preference of the short tailed Opossum monodelphis domestica
Neuroscience, 2014Co-Authors: Adele M. H. Seelke, James C. Dooley, Leah KrubitzerAbstract:The gray short-tailed Opossum (Monodelphis domestica) is a nocturnal South American marsupial that has been gaining popularity as a laboratory animal. How- ever, compared to traditional laboratory animals like rats, very little is known about its behavior, either in the wild or in a laboratory setting. Here we investigated the photic pref- erence of the short-tailed Opossum. Opossums were placed in a circular testing arena and allowed to move freely between dark (0 lux) and light (1.4, 40, or 400 lux) sides of the arena. In each of these conditions Opossums spent significantly more time in the dark than in the illuminated side and a greater proportion of time in the dark than would be expected by chance. In the high-contrast (400 lux) illu- mination condition, the mean bout length (i.e., duration of one trip on the light or dark side) was significantly longer on the dark side than on the light side. When we examined the number of bouts greater than 30 and 60 s in duration, we found a significant difference between the light and dark sides in all light contrast conditions. These data indicate that the short-tailed Opossum prefers the dark to the light, and can also detect very slight differences in light intensity. We conclude that although rats and Opossums share many similar characteristics, including ecological niche, their divergent evolutionary heritage results in vastly different behavioral capabilities. Only by observing the behavioral capabilities and preferences of Opossums will we be able to manipulate the experimental environment to best elicit and elucidate their behavior and alterations in behavior that can arise from experimental manipulations. 2014 IBRO. Published by Elsevier Ltd. All rights reserved.
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Photic preference of the short-tailed Opossum (Monodelphis domestica)
Neuroscience, 2014Co-Authors: Adele M. H. Seelke, James C. Dooley, Leah KrubitzerAbstract:The gray short-tailed Opossum (Monodelphis domestica) is a nocturnal South American marsupial that has been gaining popularity as a laboratory animal. However, compared to traditional laboratory animals like rats, very little is known about its behavior, either in the wild or in a laboratory setting. Here we investigated the photic preference of the short-tailed Opossum. Opossums were placed in a circular testing arena and allowed to move freely between dark (0 lux) and light (∼1.4, 40, or 400 lux) sides of the arena. In each of these conditions Opossums spent significantly more time in the dark than in the illuminated side and a greater proportion of time in the dark than would be expected by chance. In the high-contrast (∼400 lux) illumination condition, the mean bout length (i.e., duration of one trip on the light or dark side) was significantly longer on the dark side than on the light side. When we examined the number of bouts greater than 30 and 60s in duration, we found a significant difference between the light and dark sides in all light contrast conditions. These data indicate that the short-tailed Opossum prefers the dark to the light, and can also detect very slight differences in light intensity. We conclude that although rats and Opossums share many similar characteristics, including ecological niche, their divergent evolutionary heritage results in vastly different behavioral capabilities. Only by observing the behavioral capabilities and preferences of Opossums will we be able to manipulate the experimental environment to best elicit and elucidate their behavior and alterations in behavior that can arise from experimental manipulations.
Richard J Auchus - One of the best experts on this subject based on the ideXlab platform.
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formation of 5α reduced androgens in the testes and urogenital tract of the grey short tailed Opossum monodelphis domestica
Reproduction Fertility and Development, 2009Co-Authors: Richard J Auchus, Andrew J PaskAbstract:Testicular 5α-reduced androgens, largely 5α-androstane-3α,17β-diol (androstanediol), are responsible for virilisation of pouch young in one marsupial (the tammar wallaby), but are not formed until later in development in another marsupial (the brushtail possum) and in rodents. Because the mechanism of virilisation of the urogenital tract in the grey short-tailed Opossum Monodelphis domestica has never been defined, androgen formation and metabolism were investigated in this species. Testis fragments from grey short-tailed Opossums of a wide range of ages were incubated with ( 3 H)-progesterone and the metabolites were separated by high-performance liquid chromatography (HPLC). The only 19-carbon metabolites identified in the youngest ages (5-26 days) and the major metabolites in adult testes were testosterone and androstenedione. At 30, 42 and 49 days of age, dihydrotestosterone and small amounts of androstanediol were present. Time-sequence studies indicated that dihydrotestosterone and androstanediol were formed from the 5α-reduction (and 3-keto reduction) of testosterone. In a second series of experiments, tissue fragments of a variety of urogenital tract tissues were incubated with ( 3 H)-testosterone and the metabolites separated by HPLC. During the interval in which male urogenital tract differentiation takes place in this species (between Days 15 and 28), the major metabolite identified was dihydrotestosterone. We conclude that the timing of 5α-reductase expression in the testes of the grey short-tailed possum resembles that of rodents and the brushtail possum rather than that of the tammar wallaby and that dihydrotestosterone is probably the intracellular androgen responsible for virilisation of the urogenital tract in this species.
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formation of 5α reduced androgens in the testes and urogenital tract of the grey short tailed Opossum monodelphis domestica
Reproduction Fertility and Development, 2009Co-Authors: Richard J Auchus, Andrew J PaskAbstract:Testicular 5alpha-reduced androgens, largely 5alpha-androstane-3alpha,17beta-diol (androstanediol), are responsible for virilisation of pouch young in one marsupial (the tammar wallaby), but are not formed until later in development in another marsupial (the brushtail possum) and in rodents. Because the mechanism of virilisation of the urogenital tract in the grey short-tailed Opossum Monodelphis domestica has never been defined, androgen formation and metabolism were investigated in this species. Testis fragments from grey short-tailed Opossums of a wide range of ages were incubated with [3H]-progesterone and the metabolites were separated by high-performance liquid chromatography (HPLC). The only 19-carbon metabolites identified in the youngest ages (5-26 days) and the major metabolites in adult testes were testosterone and androstenedione. At 30, 42 and 49 days of age, dihydrotestosterone and small amounts of androstanediol were present. Time-sequence studies indicated that dihydrotestosterone and androstanediol were formed from the 5alpha-reduction (and 3-keto reduction) of testosterone. In a second series of experiments, tissue fragments of a variety of urogenital tract tissues were incubated with [3H]-testosterone and the metabolites separated by HPLC. During the interval in which male urogenital tract differentiation takes place in this species (between Days 15 and 28), the major metabolite identified was dihydrotestosterone. We conclude that the timing of 5alpha-reductase expression in the testes of the grey short-tailed possum resembles that of rodents and the brushtail possum rather than that of the tammar wallaby and that dihydrotestosterone is probably the intracellular androgen responsible for virilisation of the urogenital tract in this species.
Adele M. H. Seelke - One of the best experts on this subject based on the ideXlab platform.
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photic preference of the short tailed Opossum monodelphis domestica
Neuroscience, 2014Co-Authors: Adele M. H. Seelke, James C. Dooley, Leah KrubitzerAbstract:The gray short-tailed Opossum (Monodelphis domestica) is a nocturnal South American marsupial that has been gaining popularity as a laboratory animal. How- ever, compared to traditional laboratory animals like rats, very little is known about its behavior, either in the wild or in a laboratory setting. Here we investigated the photic pref- erence of the short-tailed Opossum. Opossums were placed in a circular testing arena and allowed to move freely between dark (0 lux) and light (1.4, 40, or 400 lux) sides of the arena. In each of these conditions Opossums spent significantly more time in the dark than in the illuminated side and a greater proportion of time in the dark than would be expected by chance. In the high-contrast (400 lux) illu- mination condition, the mean bout length (i.e., duration of one trip on the light or dark side) was significantly longer on the dark side than on the light side. When we examined the number of bouts greater than 30 and 60 s in duration, we found a significant difference between the light and dark sides in all light contrast conditions. These data indicate that the short-tailed Opossum prefers the dark to the light, and can also detect very slight differences in light intensity. We conclude that although rats and Opossums share many similar characteristics, including ecological niche, their divergent evolutionary heritage results in vastly different behavioral capabilities. Only by observing the behavioral capabilities and preferences of Opossums will we be able to manipulate the experimental environment to best elicit and elucidate their behavior and alterations in behavior that can arise from experimental manipulations. 2014 IBRO. Published by Elsevier Ltd. All rights reserved.
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Photic preference of the short-tailed Opossum (Monodelphis domestica)
Neuroscience, 2014Co-Authors: Adele M. H. Seelke, James C. Dooley, Leah KrubitzerAbstract:The gray short-tailed Opossum (Monodelphis domestica) is a nocturnal South American marsupial that has been gaining popularity as a laboratory animal. However, compared to traditional laboratory animals like rats, very little is known about its behavior, either in the wild or in a laboratory setting. Here we investigated the photic preference of the short-tailed Opossum. Opossums were placed in a circular testing arena and allowed to move freely between dark (0 lux) and light (∼1.4, 40, or 400 lux) sides of the arena. In each of these conditions Opossums spent significantly more time in the dark than in the illuminated side and a greater proportion of time in the dark than would be expected by chance. In the high-contrast (∼400 lux) illumination condition, the mean bout length (i.e., duration of one trip on the light or dark side) was significantly longer on the dark side than on the light side. When we examined the number of bouts greater than 30 and 60s in duration, we found a significant difference between the light and dark sides in all light contrast conditions. These data indicate that the short-tailed Opossum prefers the dark to the light, and can also detect very slight differences in light intensity. We conclude that although rats and Opossums share many similar characteristics, including ecological niche, their divergent evolutionary heritage results in vastly different behavioral capabilities. Only by observing the behavioral capabilities and preferences of Opossums will we be able to manipulate the experimental environment to best elicit and elucidate their behavior and alterations in behavior that can arise from experimental manipulations.
Ellis C Greiner - One of the best experts on this subject based on the ideXlab platform.
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lack of sarcocystis neurona antibody response in virginia Opossums didelphis virginiana fed sarcocystis neurona infected muscle tissue
Journal of Parasitology, 2006Co-Authors: Ellis C GreinerAbstract:Serum was collected from laboratory-reared Virginia Opossums (Didelphis virginiana) to determine whether experimentally infected Opossums shedding Sarcocystis neurona sporocysts develop serum antibodies to S. neurona merozoite antigens. Three Opossums were fed muscles from nine-banded armadillos (Dasypus novemcinctus), and 5 were fed muscles from striped skunks (Mephitis mephitis). Serum was also collected from 26 automobile-killed Opossums to determine whether antibodies to S. neurona were present in these Opossums. Serum was analyzed using the S. neurona direct agglutination test (SAT). The SAT was modified for use with a filter paper collection system. Antibodies to S. neurona were not detected in any of the serum samples from Opossums, indicating that infection in the Opossum is localized in the small intestine. Antibodies to S. neurona were detected in filter-paper-processed serum samples from 2 armadillos naturally infected with S. neurona.
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besnoitia oryctofelisi n sp protozoa apicomplexa from domestic rabbits
Parasitology, 2003Co-Authors: C Sreekumar, D E Hill, L Venturini, M C Venturini, Ellis C GreinerAbstract:A species of Besnoitia from naturally infected rabbits from Argentina was propagated experimentally in mice, gerbils, rabbits, cats, and cell cultures. Cats fed tissue cysts from rabbits shed oocysts with a prepatent period of nine to 13 days. Sporulated oocysts were infective to gerbils, rabbits, outbred Swiss Webster and interferon gamma gene knockout mice. Bradyzoites were infective orally to gerbils and cats. Tachyzoites were successfully cultivated and maintained in vitro in bovine monocytes and African green monkey kidney cells. Schizonts were seen in the lamina propria of the small intestine of cats fed tissue cysts; the largest ones measured 52×45 μm. Schizonts were also present in mesenteric lymph nodes, livers, and other extra-intestinal organs of cats fed tissue cysts. Oocysts were 10–14×10–13 μm in size. This rabbit-derived species of Besnoitia resembled B. darlingi of the North American Opossum, Didelphis virginiana with an Opossum-cat cycle, but it was not transmissible to D. virginiana , and B. darlingi of Opossums was not transmissible to rabbits. Based on biological, serological, antigenic, and molecular differences between the rabbit and the Opossum Besnoitia , a new name, B. oryctofelisi is proposed for the parasite from domestic rabbits from Argentina.
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sporocyst size of isolates of sarcocystis shed by the virginia Opossum didelphis virginiana
Veterinary Parasitology, 2001Co-Authors: J B Dame, Ellis C GreinerAbstract:Abstract The Virginia Opossum (Didelphis virginiana) is a definitive host for multiple Sarcocystis species including Sarcocystis neurona, one of the causative agents of equine protozoal myeloencephalitis (EPM), a severe, neuromuscular disease of horses. Size and morphologic characteristics of isolates of Sarcocystis shed by the Opossum were examined to determine if differences were useful in discriminating between the isolates and/or species. Collections of sporocysts from 17 Opossums were molecularly characterized and measured using an ocular micrometer. The mean sporocyst size of isolates of S. neurona was 10.7 μm ×7.0 μm , Sarcocystis falcatula 11.0 μm ×7.1 μm , Sarcocystis speeri 12.2 μm ×8.8 μm , 1085-like isolate 10.9 μm ×6.8 μm , and 3344-like isolate 19.4 μm ×10.5 μm . The length and width of S. speeri were statistically different (p
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The striped skunk (Mephitis mephitis) is an intermediate host for Sarcocystis neurona
International journal for parasitology, 2001Co-Authors: Charles A. Yowell, Debra C. Sellon, Melissa T. Hines, Pamela E. Ginn, Ellis C GreinerAbstract:Striped skunks, initially negative for antibodies to Sarcocystisneurona, formed sarcocysts in skeletal muscles after inoculation with S. neurona sporocysts collected from a naturally infected Virginia Opossum (Didelphisvirginiana). Skunks developed antibodies to S.neurona by immunoblot and muscles containing sarcocysts were fed to laboratory-reared Opossums which then shed sporulated Sarcocystis sporocysts in their faeces. Mean dimensions for sporocysts were 11.0×7.5 μm and each contained four sporozoites and a residuum. Sarcocysts from skunks and sporocysts from Opossums fed infected skunk muscle were identified as S. neurona using PCR and DNA sequence analysis. A 2-month-old, S.neurona-naive pony foal was orally inoculated with 5×105 sporocysts. Commercial immunoblot for antibodies to S.neurona performed using CSF collected from the inoculated pony was low positive at 4 weeks p.i., positive at 6 weeks p.i., and strong positive at 8 weeks p.i. Gamma-interferon gene knockout mice inoculated with skunk/Opossum derived sporocysts developed serum antibodies to S.neurona and clinical neurologic disease. Merozoites of S.neurona present in the lung, cerebrum, and cerebellum of mice were detected by immunohistochemistry using polyclonal antibodies to S.neurona. Based on the results of this study, the striped skunk is an intermediate host of S.neurona.