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Ronald D. Ley - One of the best experts on this subject based on the ideXlab platform.

  • Photobiology of Monodelphis Domestica.
    Developmental and comparative immunology, 2000
    Co-Authors: Ronald D. Ley, Vivienne E. Reeve, Donna Frances Kusewitt
    Abstract:

    The gray, short-tailed opossum, Monodelphis Domestica, has been used for photobiologic studies since 1984. The presence of a light-activated DNA repair pathway in the tissues of Monodelphis has been used to identify pyrimidine dimers in DNA as initiating events for a number of ultraviolet radiation (UVR)-induced pathologies of the skin and cornea. Furthermore, Monodelphis, unlike common laboratory rodents, is susceptible to the induction of melanoma by UVR alone.

  • Ultraviolet Radiation A-induced Precursors of Cutaneous Melanoma in Monodelphis Domestica
    Cancer research, 1997
    Co-Authors: Ronald D. Ley
    Abstract:

    Two groups of 30 dorsally shaved opossums ( Monodelphis Domestica ) were exposed three times per week for 81 weeks to 250 J/m2 of UV radiation from FS40 sunlamps (∼150 J/m2 of UV radiation B; UV-B), or to 2.5 × 104 J/m2 of UV radiation A (UV-A) from filtered F40BLB fluorescent lamps (black lights). Animals were monitored for the apppearance of nonmelanoma skin tumors (NMSTs) and melanocytic hyperplasia (MH). After 81 weeks of exposures, the prevalence of NMSTs was 71% and 4% for animals exposed to UV-B and UV-A, respectively. The difference between the treatment groups was statistically significant ( P 0.05). Thus, a dose of UV-A that was relatively ineffective in producing NMSTs, compared to UV-B, was as effective as UV-B in the induction of MH. If, as shown previously, MH is the precursor lesion for melanoma in this model, these results suggest that the action spectra for the induction of melanoma and NMSTs in the opossum are different.

  • Photorepair of Ultraviolet Radiation (UVR)‐lnduced Pyrimidine Dimers in Lens Epithelial DNA of Monodelphis Domestica
    Photochemistry and photobiology, 1997
    Co-Authors: Gregory B. Tafoya, James M. Gale, Ronald D. Ley
    Abstract:

    — The repair of UV radiation-induced pyrimidine dimers has been measured in lens epithelial DNA of the marsupial Monodelphis Domestica using a pyrimidine dimerspecific endonuclease from Micrococcus luteus. Approximately 40% of the initially induced dimers were repaired during 90 min exposures to photoreactivating light. This capacity of the lens epithelium to photorepair pyrimidine dimers may provide a means with which to determine whether pyrimidine dimers in lens epithelial DNA are involved in UV radiation-induced pathologic changes of the lens.

  • S-100 Immunoreactivity in Melanomas of the South American Opossum Monodelphis Domestica
    Veterinary pathology, 1997
    Co-Authors: Donna Frances Kusewitt, Katarzyna B. Miska, Ronald D. Ley
    Abstract:

    S-100 immunoreactivity was determined 1) in foci of melanocytic hyperplasia, 2) in naturally occurring, ultraviolet radiation-induced, and 9,10-dimethyl-1,2-benzanthracene (DMBA)-induced primary melanomas, and 3) in metastatic melanoma lesions in the South American opossum Monodelphis Domestica. Preneoplastic lesions of melanocytic hyperplasia contained scattered cells with S-100-positive nuclei. All primary melanomas, with the exception of a single DMBA-induced tumor, contained cells with S-100-positive nuclei. The pattern of S-100 reactivity in tumors varied from large foci of S-100-positive cells to scattered individual S-100-positive cells. Lymph node metastases were S-100 positive, but metastatic masses in internal organs were usually S-100 negative. Although S-100 reactivity did not distinguish preneoplastic lesions from tumors or benign melanomas from malignant melanomas, identification of metastatic tumor cells clearly demonstrated malignancy.

  • Purification and characterization of fibroblast growth factors from the opossum, Monodelphis Domestica, brain.
    Neuroscience letters, 1992
    Co-Authors: Carol L. K. Sabourin, Ronald D. Ley
    Abstract:

    Abstract An extract from the brain of the opossum Monodelphis Domestica was fractionated by heparin affinity chromatography. A major peak of mitogenic activity (heparin binding growth factor 2, HBGF-2) eluted from heparin-Sepharose between 1.7 and 2.0 M NaCl. Antisera specific for bovine bFGF detected four polypeptides of 17.5–23 kDa in opossum brain HBGF-2 preparations. Opossum brain heparin binding growth factor 1 (HBGF-1), a minor peak of activity, eluted from heparin-Sepharose at 1.1 NaCl and contained a 16.2 kDa protein that cross-reacted with antiserum against bovine aFGF.

John L Vandeberg - One of the best experts on this subject based on the ideXlab platform.

  • Monodelphis Domestica as a fetal intra-cerebral inoculation model for Zika virus pathogenesis
    2019
    Co-Authors: John M. Thomas, Juan Garcia, Terry M, Lozano I, Quintanilla O, Carlo-silva D, M.l. Morales, John L Vandeberg
    Abstract:

    ABSTRACT Monodelphis Domestica, also known as the laboratory opossum, is a marsupial native to South America. At birth, these animals are developmentally equivalent to human embryos at approximately 5 weeks of gestation which, when coupled with other characteristics including the size of the animals, the development of a robust immune system during juvenile development, and the relative ease of experimental manipulation, have made M. Domestica a valuable model in many areas of biomedical research. However, their suitability as models for infectious diseases, especially diseases caused by viruses such as Zika virus (ZIKV), is currently unknown. Here, we describe the replicative effects of ZIKV using a fetal intra-cerebral model of inoculation. Using immunohistochemistry and in situ hybridization, we found that opossum embryos and fetuses are susceptible to infection by ZIKV administered intra-cerebrally, that the infection persists long term, and that the infection and viral replication consistently results in neural pathology and may occasionally result in global growth restriction. These results demonstrate the utility of M. Domestica as a new animal model for investigating ZIKV infection in vivo. This new model will facilitate further inquiry into viral pathogenesis, particularly for those viruses that are neurotropic, that may require a host with the ability to support sustained viral infection, and/or that may require intra-cerebral inoculations of large numbers of embryos or fetuses. AUTHOR SUMMARY Here we show that the laboratory opossum (Monodelphis Domestica) is a valuable new model for studying Zika virus pathogenesis. Newborns are at the developmental stage of 5-week human embryos. Zika virus inoculated on a single occasion into the brains of pups at the human developmental stages of 8-20 weeks post conception replicated in neuronal cells and persisted as a chronic infection until the experimental endpoint at 74-days post infection. In addition, we observed global growth restriction in one of 16 inoculated animals; global growth restriction has been observed in humans and other animal models infected with Zika virus. The results illustrate great potential for this new animal model for high throughput research on the neurological effects of Zika virus infection of embryos and fetuses.

  • genome wide histone state profiling of fibroblasts from the opossum Monodelphis Domestica identifies the first marsupial specific imprinted gene
    BMC Genomics, 2014
    Co-Authors: Kory C Douglas, John L Vandeberg, Xu Wang, Madhuri Jasti, Abigail Wolff, Andrew G Clark, Paul B. Samollow
    Abstract:

    Background Imprinted genes have been extensively documented in eutherian mammals and found to exhibit significant interspecific variation in the suites of genes that are imprinted and in their regulation between tissues and developmental stages. Much less is known about imprinted loci in metatherian (marsupial) mammals, wherein studies have been limited to a small number of genes previously known to be imprinted in eutherians. We describe the first ab initio search for imprinted marsupial genes, in fibroblasts from the opossum, Monodelphis Domestica, based on a genome-wide ChIP-seq strategy to identify promoters that are simultaneously marked by mutually exclusive, transcriptionally opposing histone modifications.

  • Laboratory opossum (Monodelphis Domestica) model for melanoma chemoprevention
    Journal of Cancer Science & Therapy, 2012
    Co-Authors: Hareesh B. Nair, John L Vandeberg
    Abstract:

    Melanoma is the most aggressive form of skin cancer. Developments in melanoma basic research and therapeutic interventions have advanced tremendously with help of animal models of this disease. Transgenic and knockout mice have provided a wide array of melanoma models, which are primarily used for studying molecular pathways and developing treatment strategies. To the best of our knowledge, there has been no natural animal model for research on chemoprevention of melanoma induced by UV light alone. In this editorial, we discuss the potential of the laboratory opossum (Monodelphis Domestica) as a natural model for research on chemoprevention of melanoma.

  • A new DNA marker, U15557, is linked to protease inhibitor and adenylate kinase-1 in the laboratory opossum, Monodelphis Domestica.
    Animal genetics, 2009
    Co-Authors: Andrey A. Perelygin, Paul B. Samollow, Susan M. Mahaney, L M Perelygina, L. M. Cherry, John L Vandeberg
    Abstract:

    Summary A 323-bp DNA fragment (U15557) was isolated, cloned, and sequenced after polymerase chain reaction (PCR) amplification from Monodelphis Domestica genomic DNA. AHindIII restriction fragment length polymorphism was identified in this species using the U15557 PCR. fragment as a hybridization probe. DNA samples exhibited either a 6.4kb band, a 7.2 kb band, or both bands simultaneously. Behaviour of these two variants in family studies was consistent with codominant autosomal inheritance. Linkage between this marker and the loci encoding protease inhibitor (PI) and adenylate kinase 1 (AK1) was found in M. Domestica.

  • Immunotolerance in the laboratory opossum (Monodelphis Domestica) to xenografted mouse melanoma.
    Contemporary topics in laboratory animal science, 2005
    Co-Authors: Zhiqiang Wang, John L Vandeberg
    Abstract:

    Monodelphis Domestica, a South American marsupial, has been developed as a laboratory animal model for allogeneic and xenogeneic cancer research by taking advantage of its underdeveloped immune system in the early days of life. The limited immunological capability during this period provides an opportunity to induce tolerance to grafted tumor tissue in juvenile and adult opossums. In this study, we injected multiple doses of mouse B16 melanoma cells into opossums at different developmental ages (i.e., suckling young, juveniles, and adults) to determine whether immunotolerance could develop as a result of repeated "desensitizing" injections. We found that establishment and growth of xenografted mouse melanoma cells could be established after full immune capability of the animals had been achieved. The tumors thus produced could sustain their growth for as long as 6 weeks before beginning to regress. Our results highlight the potential of the laboratory opossum as a natural mammalian model to study host immunotolerance to xenografted tumor cells.

Zdenek Halata - One of the best experts on this subject based on the ideXlab platform.

Leah Krubitzer - One of the best experts on this subject based on the ideXlab platform.

  • Cortical plasticity following stripe rearing in the marsupial Monodelphis Domestica: neural response properties of V1
    Journal of neurophysiology, 2016
    Co-Authors: James C. Dooley, Michaela S. Donaldson, Leah Krubitzer
    Abstract:

    These results are the first description of visual response properties of the most commonly studied marsupial model organism, the short-tailed opossum (Monodelphis Domestica). Further, these results...

  • Visual acuity in the short-tailed opossum (Monodelphis Domestica).
    Neuroscience, 2012
    Co-Authors: James C. Dooley, Hoang Nguyen, Adele M. H. Seelke, Leah Krubitzer
    Abstract:

    Monodelphis Domestica (short-tailed opossum) is an emerging animal model for studies of neural development due to the extremely immature state of the nervous system at birth and its subsequent rapid growth to adulthood. Yet little is known about its normal sensory discrimination abilities. In the present investigation, visual acuity was determined in this species using the optokinetic test (OPT), which relies on involuntary head tracking of a moving stimulus and can be easily elicited using a rotating visual stimulus of varying spatial frequencies. Using this methodology, we determined that the acuity of Monodelphis is 0.58 cycles per degree (cpd), which is similar to the acuity of rats using the same methodology, and higher than in mice. However, acuity in the short-tailed opossum is lower than in other marsupials. This is in part due to the methodology used to determine acuity, but may also be due to differences in diel patterns, lifestyle and phylogeny. We demonstrate that for the short-tailed opossum, the OPT is a rapid and reliable method of determining a baseline acuity and can be used to study enhanced acuities due to cortical plasticity.

  • normal organ weights serum chemistry hematology and cecal and nasopharyngeal bacterial cultures in the gray short tailed opossum Monodelphis Domestica
    Journal of The American Association for Laboratory Animal Science, 2010
    Co-Authors: Kristin D Evans, Leah Krubitzer, Terry Hewett, Cindy J Clayton, Stephen M Griffey
    Abstract:

    Gray short-tailed opossums (Monodelphis Domestica) currently are used in genetic, developmental, oncology, and neurologic research. Little is known about their natural flora or potential for pathogenic infectious disease. The present study aims to improve existing comparative normal blood and organ weight values available to researchers and to describe flora of clinically normal M. Domestica to obtain an understanding of potential pathogenic flora in clinically abnormal animals. For evaluation of serum hematology and serum chemistry, clinically normal animals were assigned to 1 of 6 groups stratified by age (younger than 1 y, 1 to 2 y, and 2 to 3 y) and sex. Hemoglobin and phosphorus levels were higher in male than female opossums, whereas monocyte and eosinophil counts were greater in females than males. Hemoglobin concentration decreased with increasing age. The youngest group had significantly higher levels of serum alkaline phosphatase and lower serum protein levels compared with older age groups. Liver and kidney weights of adult animals (1 to 3 y) were greater in female than male opossums. The predominant nasopharyngeal flora in 20 clinically normal animals from the 2- to 3-y-old group were Streptococcus viridans, Escherichia coli, and coagulase-negative Staphylococcus spp.; predominant cecal organisms were Escherichia coli and Citrobacter spp. The availability of reference hematologic values and flora for Monodelphis Domestica will aid researchers in comparisons and analysis of experimental data and in diagnosis and evaluation of potential pathogens in clinically ill animals.

  • Organization and connections of V1 in Monodelphis Domestica.
    The Journal of comparative neurology, 2000
    Co-Authors: Dianna M. Kahn, Kelly J. Huffman, Leah Krubitzer
    Abstract:

    We examined the internal organization and connections of the primary visual area, V1, in the South American marsupial Monodelphis Domestica. Multiunit electrophysiological recording techniques were used to record from neurons at multiple sites. Receptive field location, size, progressions, and reversals were systematically examined to determine the visuotopic organization of V1 and its boundaries with adjacent visual areas. As in other mammals, a virtually complete representation of the visual hemifield was observed in V1, which was coextensive with a region of dense myelination. The vertical meridian was represented at the rostrolateral boundary of the field, the upper visual quadrant was represented caudolaterally, whereas the lower visual quadrant was represented rostromedially. Injections of fluorescent tracers into V1 revealed dense connections with cortex immediately adjacent to the rostrolateral boundary, in peristriate cortex (PS or V2). Connections were also consistently observed with a caudotemporal area (CT), entorhinal cortex (EC), and multimodal cortex (auditory/visual, A/V). These results demonstrate that M. Domestica possess a highly differentiated neocortex with clear functional and architectonic cortical field boundaries, as well as discrete patterns of cortical connections. Some connections of V1 are similar to those observed in eutherian mammals, such as connections with V2 and extrastriate areas (e.g., CT), which suggests that there are general features of visual system organization that all mammals posses due to retention from a common ancestor. On the other hand, connections of V1 with EC and multimodal cortex may be a primitive feature of visual cortex that was lost in some lineages, may be a derived feature of marsupial neocortex, or may be a feature particular to mammals with small brains. J. Comp. Neurol. 428:337–354, 2000. © 2000 Wiley-Liss, Inc.

C Schulze - One of the best experts on this subject based on the ideXlab platform.