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antithrombin iii (at3) polymorphism in the marsupial monodelphis domestica: identification and genetics.antithrombin iii polymorphism was observed in the gray short-tailed opossum, monodelphis domestica, by either one-dimensional polyacrylamide gel electrophoresis (page; ph 7.9), two-dimensional page (agarose, ph 5.4; 12% t, ph 7.9), or isoelectric focusing (ph 4.2-4.9) followed by immunoblotting with rabbit antiserum to human antithrombin iii. family studies demonstrated an inheritance of three codominant autosomal alleles, at3a, at3b, and at3c, and a population study revealed frequencies of 0.70 ...19921296573
purification and characterization of fibroblast growth factors from the opossum, monodelphis domestica, brain.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 contain ...19921380142
identification of a transforming ras oncogene in an ultraviolet radiation-induced corneal tumor of monodelphis domestica.chronic exposure of the gray, short-tailed oppossum, monodelphis domestica to ultraviolet radiation (uvr) induces mesenchymal tumors of the cornea. high molecular weight dna samples from 6 uvr-induced corneal tumors were assayed for their ability to transform nih 3t3 cells to tumorigenicity. nih 3t3 cells transfected with dna from 5 of the corneal tumors produced 14 tumors in nude mice. cell lines were established from these tumors. dna from 13 of 14 tumor cell lines contained repetitive opossum ...19921561240
milk composition in an american marsupial (monodelphis domestica).1. twenty one sequential milk samples from an american marsupial (monodelphis domestica) were analyzed. 2. the solids fraction was relatively low initially (10% w/w) and then increased to about 30% at mid-lactation where it remained until lactation ceased. 3. during the first 50 days of lactation the relative proportions of protein, fat and carbohydrate were 36, 28 and 34%, respectively, of the solids fraction. 4. sodium and magnesium concentrations were constant; however levels of potassium and ...19911769214
production of interleukin-1 in a south american opossum (monodelphis domestica).a homologous thymocyte costimulatory assay using thymocytes from a south american opossum (monodelphis domestica) detected and measured interleukin-1 (il-1). opossum il-1 was obtained from lipopolysaccharide-stimulated macrophage and skin cultures and its molecular weight was determined to be 15,000 to 17,000. opossum il-1 did not stimulate proliferation of murine thymocytes; conversely, neither human nor murine il-1 stimulated opossum thymocytes. anti-human il-1 antibodies were also not reactiv ...19911773863
cellular immune response of a marsupial, monodelphis domestica.marsupials are interesting subjects for studies of comparative and developmental immunology because they separated from eutherian mammals over 100 million years ago and because the newborns are still in a fetal state. we studied cellular immunity in a fully pedigreed colony of the marsupial, m. domestica (commonly called the gray short-tailed opossum). peripheral blood lymphocytes were separated on nylon wool columns into adherent cells bearing surface immunoglobulin (b cells) and nonadherent ce ...19911829419
macroscopic and histologic study to differentiate large glands and bulbi in the perianal body region of the male gray short-tailed opossum, monodelphis domestica.on either side of the cloaca of the male monodelphis domestica, there is a large pack of globular structures lying between the external skin and the ischial arch. the structures within each of these bilateral complexes can be classified into three groups. group 1 comprises different kinds of glands. there are two large glands, "paraproctic glands" according to schaffer (1940), whose spacious cavity is bounded by a secretory epithelium. the secretion is holocrine in a way that cells are shed into ...19911883869
chicken gnrh ii occurs together with mammalian gnrh in a south american species of marsupial (monodelphis domestica).two molecular forms of gonadotropin-releasing hormone (gnrh) were demonstrated in hypothalamic extracts of m. domestica using high performance liquid chromatography and radioimmunoassay with specific gnrh antisera. one form eluted in the same position as synthetic mammalian gnrh and was quantified equally by two mammalian gnrh antisera, while the second form coeluted with synthetic chicken gnrh ii and was quantified equally with two chicken gnrh ii antisera. the finding of chicken gnrh ii in a s ...19902199949
thermogenic capabilities of the opossum monodelphis domestica when warm and cold acclimated: similarities between american and australian marsupials.1. monodelphis domestica is a small marsupial mammal from south america. its thermogenic abilities in the cold were determined when the opossums were both warm (wa) and cold (ca) acclimated. maximum heat production of m. domestica was obtained at low temperatures in helium-oxygen. 2. basal metabolic rate (bmr) in the wa animals was 3.2 w/kg and mean body temperature was 32.6 degrees c at 30 degrees c. these values were lower than those generally reported for marsupials. nevertheless, these m. do ...19882450718
the morphogenesis of the posterior neural tube and tail in monodelphis domesticus.the process of secondary neuralation has been studied in the brazilian opossum, monodelphis domesticus. secondary neuralation in this mammal was found to have qualities of secondary neuralation that were present in both the chick and the mouse. in this study, four stages of secondary neuralation were found beginning with the medullary cord stage. other stages in the differentiation of the secondary neural tube were: differentiation of the neuroepithelium, cavitation of the medullary cord, and pr ...19892505824
immune response of a marsupial (monodelphis domestica) to sheep red blood cells.a study of the humoral immune response of a marsupial, monodelphis domestica, was performed using sheep red blood cells as the immunogen and a hemolytic titration as the assay. the primary response to a single intramuscular injection was similar to that observed in other mammalian species, except that the titers remained high for as long as 37 weeks after the initial injection. the secondary response was weaker than the primary response and diminished as early as 15 weeks after the initial injec ...19892767312
immunocytochemical localization of luteinizing hormone-releasing hormone (lhrh) in the brain and nervus terminalis of the adult and early neonatal gray short-tailed opossum (monodelphis domestica).luteinizing hormone-releasing hormone (lhrh) was detected by immunocytochemical procedures in cells and fibers in the brain and in the nervus terminalis of the adult and neonatal gray, short-tailed opossum (monodelphis domestica). as in several species of eutherian mammals, lhrh-immunoreactive cells and fibers were seen in the medial septal nuclei, nucleus, and tract of the diagonal band and olfactory tubercle. surprisingly, few lhrh-immunoreactive cells were found in the hypothalamus or in the ...19883056990
transplantation, growth, and regression of mouse melanoma xenografts in neonatal marsupials.marsupials are useful for cancer research since they are born in a fetal stage of development with little immunologic competence. in this study, mouse melanoma xenografts were grown in neonatal gray opossums (monodelphis domestica) injected at 12-32 days of age. tumors appeared between 1 and 3 weeks postinjection and at least 73% of tumor-bearing animals rejected their tumors. initiation of tumor growth was rare in animals over 24 days of age and, in most cases, tumors size peaked at about 50 da ...19883179772
passively acquired immunity in the newborn of a marsupial (monodelphis domestica).a colony of fully pedigreed monodelphis domestica has been used to investigate the maternal-fetal relationship in this unique marsupial species. to determine how immunity is transferred from mothers to young in m. domestica, we hyperimmunized females with sheep red blood cells (srbc) before and during gestation. offspring from these females were collected at various times after birth, and saline extracts of the neonates were assayed for hemolysins against srbc. antibodies were present in extract ...19863752338
water balance in monodelphis domestica (didelphidae) from the semiarid caatinga of brazil.1. water conservation and energy metabolism in a semiarid-area, neotropical marsupial (monodelphis domestica) were studied in the laboratory. 2. the rate of energy consumption in this species is low, corresponding with results reported for australian and other neotropical marsupials. 3. evaporative water loss rate is low and comparable to that of several desert small rodents, when body size differences are taken into account; however, the ratio of metabolic water production-to-evaporative water ...19836132710
effect of inbreeding on juvenile mortality in some small mammal species.in breeding records for 12 species of small mammals from 9 families in 3 orders, individuals with an inbreeding coefficient of 0 were classified as non-inbred, those with inbreeding coefficients greater than 0 as inbred. juvenile mortality was defined as all deaths prior to 1/2 of the age of sexual maturity for each species. it was significantly higher for inbred than for noninbred animals in 11 of the 12 species using a 1-tailed sign test, and by fisher's exact test in 3 species. monodelphis do ...19827043080
care and breeding of the gray, short-tailed opossum (monodelphis domestica)husbandry procedures were developed for the gray short-tailed opossum (monodelphis domestica) based on experience with several colonies that were self-sustaining for up to 4 years (five generations). individual adult animals (80-155 g) were maintained in modified single rat or guinea pig cages, although larger cages with floor areas of at least 2,000 cm2 were required for breeding. diets consisted primarily of ground meat, dried milk powder, wheat germ, and vitamin supplements. switching males i ...19827144118
[the cellular aspects of the development of synovial joints and articular cartilage].there have been many reports on the histological development of mammalian diarthrodial or synovial joints. while these are useful for comparative purposes, they tell us little of the cellular basis of joint morphogenesis which must underlie a number of morphogenetic defects. the process of joint morphogenesis is complex and can be subdivided into a number of facets and this report will focus on 2 of them. first, the process of joint cavitation in the chick metatarsophalangeal joint, where we pro ...19957478442
development and migration of olfactory neurones in the nervous system of the neonatal opossum.the neonatal opossum (monodelphis domestica) was used to assess how different populations of cells are generated in the olfactory region, and how they migrate along pathways to the central nervous system. developing nerve cells were immunocytochemically labelled using antisera directed against two specific markers of olfactory receptor neurones: olfactory marker protein (omp) and the dipeptide carnosine. in new-born opossums both carnosine and omp are already co-expressed in primary olfactory ne ...19957479995
does early monocular enucleation in a marsupial affect the surviving uncrossed retinofugal pathway?monocular enucleations have been done during early stages (postnatal days 3 to 9) of visual system development of monodelphis domestica, in order to determine whether in this marsupial, as in several eutherian mammals, there are any interactions between the pathways from the two eyes in establishing the uncrossed retinofugal projection. we have examined the distribution and the number of retrogradely labelled ganglion cells that project to the same side of the brain from the surviving eyes short ...19957649832
why do spermatozoa of american marsupials form pairs? a clue from the analysis of sperm-pairing in the epididymis of the grey short-tailed opossum, monodelphis domestica.in order to understand the evolutionary significance of sperm-pairing in american marsupials, an ultrastructural investigation was made of this process in the south american grey short-tailed opossum, monodelphis domestica. one epididymis from each animal (5) was fixed for light and electron microscopy and divided into 18 segments. the contralateral tract was divided into similar segments and assessments made of the total number of spermatozoa and the proportion of sperm-pairs. the mean total sp ...19937689796
hprt activity in embryos of a south american opossum monodelphis domestica.marsupial females show preferential paternal x-inactivation. however, the time at which x-inactivation occurs in early development has not yet been determined. a double microassay which measures the activities of x-linked hypoxanthine phosphoribosyl transferase (hprt) and the autosomally-coded adenine phosphoribosyl transferase (aprt) from the same sample was performed on a collection of embryos from a south american opossum monodelphis domestica. the embryos ranged in age from the 2-cell stage ...19947878225
projection of visuotopically organized afferents to the dorsal thalamus in the opossum, monodelphis domestica.retrogradely transported dyes, fluorogold and fast blue were injected into both sides of the dorsal thalamus in the monodelphis opossum. projection of the presumed primary visual cortical area, superior colliculus and parabigeminal nucleus to the dorsal lateral geniculate nucleus and the lateral posterior--lateral intermedius nuclear complex were described. they show close similarities to the homologous projections in the north american opossum, insectivores and some rodents. in comparison with ...19947887182
recent advances in cutaneous melanoma oncogenesis research.the oncogenic transformation of epidermal melanocytes produces primary cutaneous melanoma. in this article, previously published cytogenetic, biochemical, molecular biology, and cell biology studies of cutaneous melanoma oncogenesis are reviewed. a variety of laboratory animal models have been developed for studies of the induction of melanoma, including mice, the laboratory opossum monodelphis domestica, sinclair swine, and xiphophorus fish. some of the advantages and disadvantages of these ani ...19947919546
cloning of a marsupial dna photolyase gene and the lack of related nucleotide sequences in placental mammals.photoreactivating enzyme, dna photolyase, reduces lethal, mutagenic and carcinogenic effects of ultraviolet light (uv) by catalyzing near uv or visible light-dependent repair of cyclobutane pyrimidine dimers (cpds) in dna. the enzyme activity has been detected in a wide variety of organisms ranging from bacteria to nonplacental mammals. however, the evidence for photoreactivation in placental mammals, including humans, is controversial. as a first step to identify the presence and activity of th ...19947937136
immunocytochemical localization of vacuolar h-atpase in the opossum (monodelphis domestica) kidney: comparison with the rat.with two different antibodies (a monoclonal antibody to the c terminus of the 31-kd subunit of h-atpase and a polyclonal rabbit antiserum to whole bovine h-atpase) the vacuolar-type h-atpase pump in the different nephron segments of the gray short-tailed (monodelphis domestica) opossum kidney has been immunocytochemically localized. there was moderate staining of the brush border and subvillar invaginations in the proximal convoluted tubules (pct) of the opossum kidney only with the rabbit antis ...19948025229
spatial behavior in the brazilian short-tailed opossum (monodelphis domestica): comparison with the norway rat (rattus norvegicus) in the morris water maze and radial arm maze.the spatial behavior displayed in a swimming pool and radial arm maze by the brazilian gray, short-tailed opossum (monodelphis domestica) was compared with that of the laboratory rat (rattus norvegicus). the performance of the opossums was clearly different from that of the rats in both tasks. the opossums failed to learn to find a hidden platform in the swimming pool (place task), but they did learn to swim to a visible platform. the opossums did learn working and reference memory components of ...19948026166
igg transport across the gut of the suckling opossum (monodelphis domestica).we investigated igg transport across the gut of suckling opossums to see whether it is likely to be fc gamma r-mediated. enterocytes isolated from the proximal and distal regions of the small intestine of suckling aged 12-52 days, and reacted with indicator srbc at ph 6.0 or 7.2, bound opossum igg in rosette assays. considerable overall variation was observed in the numbers of enterocytes forming rosettes. no binding was seen with rabbit igg at these ages, or with opossum and rabbit igg when ent ...19948050619
ultrastructural characteristics of in vivo and in vitro fertilization in the grey short-tailed opossum, monodelphis domestica.to establish the mode of fertilization in a marsupial, a morphological investigation was made of the gametes of the south american grey short-tailed opossum. monodelphis domestica, at the time of fertilization in vivo and in vitro. oestrus was induced in females by the introduction of an unfamiliar male. to obtain oocytes recently fertilized in vivo, females were killed 18-24 hours after the first mating and the region of the oviduct containing eggs excised and fixed. unfertilized mature oocytes ...19938214640
linkage between complement components 6 and 7 and glutamic pyruvate transaminase in the marsupial monodelphis domestica.the sixth and seventh components of complement were found to be polymorphic and tightly linked in the laboratory opossum (monodelphis domestica), as they are in eutherian mammals. in addition, strong evidence for linkage of the c6-c7 haplotype to the gene for glutamic pyruvate transaminase (gpt) was obtained for females but not for males. this result, combined with previous observations, established as a generality that recombination is severely reduced in females of this species by comparison w ...19938259924
characterization of the k-ras gene of the marsupial monodelphis domestica.a cdna clone isolated from a plasmid library contains the complete coding sequence for the k-ras gene of the marsupial monodelphis domestica, a south american opossum. the nucleotide sequence of the coding region of the opossum k-ras gene is very similar to the k-ras coding sequences of placental mammals. the coding region of the opossum gene is 95% identical to the human gene at the nucleotide level; the human and opossum genes are 99% identical at the level of encoded amino acids. transcribed ...19938312604
aldehyde dehydrogenase (aldh) isozymes in the gray short-tailed opossum (monodelphis domestica): tissue and subcellular distribution and biochemical genetics of aldh3.polyacrylamide gel isoelectric focusing (page-ief), cellulose acetate electrophoresis, and histochemical techniques were used to examine the tissue and subcellular distribution, genetics and biochemical properties of aldehyde dehydrogenase (aldh) isozymes in a didelphid marsupial, the gray short-tail opossum (monodelphis domestica). at least 14 zones of activity were resolved by page-ief and divided into five isozyme groups and three aldh classes, based upon comparisons with properties previousl ...19911859355
topical toremifene: a new approach for cutaneous melanoma?the distribution of topically applied toremifene (0.5-1 mg/day for 5 days) in the ultraviolet b (uvb)-induced monodelphis domestica opossum melanoma model was examined. the mean concentration of toremifene measured in the skin was 1200 nmol/g, or > 500 times that detected in any other tissues (blood, brain, liver, testicles, heart, uterus, eyes). in plasma, toremifene could be detected in only one animal of six (0.04 nmol/ml). intraperitoneal administration of 0.5 mg toremifene daily for 5 days ...19938339391
uva does not photoreactivate pyrimidine dimers in cultured human fibroblasts.pyrimidine dimers were induced in duplicates of cultured human skin fibroblasts by irradiation with various doses of uvb radiation. subsequently, one set of cells was further exposed to either 5 or 10 j/cm2 of uva radiation to assess the photoreactivating activity of this spectral range in a human cell system. following irradiation, pyrimidine dimers were quantified in all cells by determining the number of endonuclease-sensitive sites (ess). no difference in the yield of ess was observed betwee ...19938162334
genetic analysis of ultraviolet radiation-induced skin hyperplasia and neoplasia in a laboratory marsupial model (monodelphis domestica).monodelphis domestica, the laboratory opossum, develops hyperplasia and neoplasia of shaved skin after repeated exposure to ultraviolet radiation (uvr). we exposed monodelphis from genetically diverse families within our colony to determine whether there are any heritable components to the risk of two distinct skin lesion phenotypes-melanocytic nevus (mn) and advanced hyperkeratosis (hk). from about 5 months of age, animals were shaved and exposed three times a week to a dose of about 125 j/m2 o ...19948141607
gnrh neurons and other cell populations migrating from the olfactory neuroepithelium.cell migration from the olfactory neuroepithelium to the brain has been widely studied during vertebrate development. immunocytochemical analysis has revealed that many of the migrating cells contain gnrh (gonadotropin-releasing hormone). the gnrh positive cells migrate from the medial olfactory placode, steam along the nasal septum, cross the basal forebrain and reach the hypothalamic and septal areas from where they control the release of hypophyseal gonadotropic peptides. a peculiar feature o ...19947864581
humoral immune response in a marsupial monodelphis domestica: anti-isotypic and anti-idiotypic responses detected by species-specific monoclonal anti-immunoglobulin reagents.we examined the humoral immune response of the laboratory opossum (monodelphis domestica) as a model marsupial species. to evaluate antibody responses, igm and igg preparations were purified from the sera of naïve monodelphis. these two immunoglobulin (ig) preparations were used to generate specific murine monoclonal antibodies for use in elisa-based serology. individual monodelphis were then immunized with a multideterminant protein antigen, a murine monoclonal antibody (mab) igg preparation de ...19958595822
early development of the optic chiasm in the gray short-tailed opossum, monodelphis domestica.we have studied the early development of the uncrossed retinofugal projection in the gray short-tailed opossum. axons that form the adult uncrossed retinofugal projection arise from the temporal crescent of the retina and reach the optic chiasm on postnatal day 7. the sites at which the uncrossed fibres segregate from the crossed fibres and the pattern of this segregation are very different from those seen in eutherian mammals. in the opossum, the uncrossed fibres segregate from the crossed fibr ...19947860795
structure and chemical coding of human, canine and opossum gallbladder ganglia.immunohistochemistry and cholinesterase histochemistry were used to evaluate the structure and neurotransmitter content of the ganglionated plexuses of the human, canine, and opossum (monodelphis domestica) gallbladders. in each species, the ganglionated plexus consisted of small (mean approximately 4 neurons/ganglion), irregularly dispersed ganglia that were interconnected by bundles of nerve fibers. the density of ganglia was about ten-fold higher in the opossum than in the human or the dog. i ...19968625395
evolution of transthyretin in marsupials.the evolution of the expression and the structure of the gene for transthyretin, a thyroxine-binding plasma protein formerly called prealbumin, was studied in three marsupial species: the south american polyprotodont monodelphis domestica, the australian polyprotodont sminthopsis macroura and the australian diprotodont petaurus breviceps. the transthyretin gene was found to be expressed in the choroid plexus of all three species. in liver it was expressed in p. breviceps and in m. domestica, but ...19957851414
expression of fibroblast growth factors in ultraviolet radiation-induced corneal tumors and corneal tumor cell lines from monodelphis domestica.chronic exposure of the gray, short-tailed opossum, monodelphis domestica, to ultraviolet radiation (uvr) induces highly vascularized mesenchymal tumors of the cornea. cell lines derived from these uvr-induced corneal tumors and the corneal tumors themselves were examined for the presence of mrna coding for basic and acidic fibroblast growth factors (fgf), transforming growth factors-beta and -alpha (tgf-beta and tgf-alpha), epidermal growth factor (egf), and tumor necrosis factor-alpha (tnf-alp ...19937683886
oligodendrocyte/myelin-immunoreactivity in the developing olfactory system.immunocytochemistry was used to characterize oligodendrocyte maturation in the developing mammalian olfactory system. postnatal day 10-16, 20, 30 and adult rats were examined, as well as postnatal day 20, 30, 40 and adult monodelphis domestica (the grey, short-tailed opossum). in rats, oligodendrocyte/myelin-immunoreactivity first appears in the accessory olfactory bulb by day 11, with labeling rapidly increasing throughout the entire bulb over the next five days. an adult pattern of immunoreact ...19957675203
repair and recovery following spinal cord injury in a neonatal marsupial (monodelphis domestica).1. repair and recovery following spinal cord injury (complete spinal cord crush) has been studied in vitro in neonatal opossum (monodelphis domestica), fetal rat and in vivo in neonatal opossum. 2. crush injury of the cultured spinal cord of isolated entire central nervous system (cns) of neonatal opossum (p4-10) or fetal rats (e15-e16) was followed by profuse growth of fibres and recovery of conduction of impulses through the crush. previous studies of injured immature mammalian spinal cord hav ...19957586707
uv-induced melanoma. a karyotype with a single translocation is stable after allografting and metastasis.metastatic melanoma cell lines were derived from a lymph node of a laboratory opossum, monodelphis domestica, which had been exposed to mid-wavelength ultraviolet radiation (uvb) initially as a suckling young, and subsequently as a shaved juvenile and adult. the melanoma cell lines were dendritic and pigmented in vitro and contained a t(6;8)(p13;q13) as the only cytogenetic abnormality. the translocation was detected in 15% of primary cultures (passage 2) from the affected lymph node and in 100% ...19957553587
the gray opossum (monodelphis domestica): a marsupial model for xenogeneic neoplasms.marsupials are born in what is essentially a fetal stage of development and are largely unprotected by endocrine or immune systems during early neonatal life. in this study, gray opossums (monodelphis domestica) were injected during neonatal life, prepubertally and in adulthood with b16 melanoma from the syngeneic c57bl/6 mouse. ten days following injection, tumors were found in animals injected on days 4, 6 and 13 of postnatal life but not in prepubertal or adult animals. because xenogeneic tum ...19854005833
culture of preantral ovarian follicles in the grey, short-tailed opossum, monodelphis domestica.a culture system designed to support the development of individual preantral mouse ovarian follicles has been employed to study follicle growth in the new world marsupial species monodelphis domestica. preantral follicles were isolated mechanically and cultured individually in microdrops under oil. preliminary results indicate that follicle growth was positively correlated to the concentration of follicle-stimulating hormone (fsh) provided, with 1.0-1.5 iu fsh ml-1 producing the best results. in ...19968870078
photorepair of ultraviolet radiation-induced pyrimidine dimers in corneal dna.the induction and photorepair of pyrimidine dimers in dna have been measured in the ultraviolet-irradiated, corneal epithelium of the marsupial, monodelphis domestica, using damage-specific nucleases from micrococcus luteus in conjunction with agarose gel electrophoresis. we observed that fs-40 sunlamps (280-400 nm) induced 7.2 +/- 1.0 x 10(-5) pyrimidine dimers per kilobase (kb) of dna per j/m2. following 100 j/m2, 50% and greater than 90% of the dimers were photorepaired during a 10- and 30-mi ...19883386657
monodelphis domestica (grey short-tailed opossum): an accessible model for studies of early neocortical development.the development of the neocortex of the marsupial monodelphis domestica has been studied from birth until adulthood. monodelphis is born after a gestational period of 14 days, a time when the neocortex is still at a two-layered "embryonic" stage of development, that is equivalent to a 13-14 day rat embryo or 6 week human embryo. the cortical plate does not begin to appear until 3 to 5 days postnatal. thus the whole of neocortical development is a postnatal phenomenon in this species, as has been ...19892596703
skilled forelimb movements in prey catching and in reaching by rats (rattus norvegicus) and opossums (monodelphis domestica): relations to anatomical differences in motor systems.traditional anatomical/behavioral classifications suggest that rats and opossums have simple motor systems and are impoverished with respect to their ability to make prehensile movements. nevertheless, the motor system in rats and opossums represent extremes in relative size and complexity suggesting that a behavioral analysis of the movement competencies of these species will provide insights into the significance of such anatomical differences. this paper examines the movements that the two sp ...19968883828
organization and postnatal development of zebrin ii antigenic compartmentation in the cerebellar vermis of the grey opossum, monodelphis domestica.the mammalian cerebellar cortex consists of a number of parasagittal purkinje cell compartments that can be demonstrated cytochemically. the afferent inputs to the cerebellum are also compartmentalized, and a complex but reproducible relationship exists between the afferents and the intrinsic maps. developmental studies in the rat have shown that many of the main features of compartmentation are already established at birth, and are therefore not easily manipulated experimentally. the compartmen ...19902298942
plasma protease inhibitor (pi) system in the laboratory opossum, monodelphis domestica.protease inhibitor (pi) polymorphism was observed in the laboratory opossum, monodelphis domestica, by either one-dimensional acid polyacrylamide gel electrophoresis (page; ph 4.6) or isoelectric focusing (ph 3.5-5.0) followed by immunoblotting with rabbit antiserum to human alpha 1-antitrypsin; but acid page produced superior resolution of the pi proteins. family studies demonstrated an inheritance of nine codominant autosomal alleles, pid, pie, pif, pig, pih, pii, pij, pik, and pim, and a popu ...19968978911
prolactin-like biological activity in the pituitary glands of the marsupial monodelphis domestica and of the amphibian rana pipiens detected by a colorimetric nb2 lymphoma cell proliferation assay.an inexpensive and reliable colorimetric microplate version of the nb2 lymphoma cell proliferation bioassay for prolactin (prl) was developed and optimized. the useful range of the assay is between 0.1 and 12.8 ng/ml in terms of rat pituitary prl. the assay can accommodate up to 20 microl sample/well. the physiological relevance of the assay was verified by measuring thyrotropin-releasing hormone (trh)-induced secretion of prl in pituitary cultures and in serum samples of neonatal rats. through ...19979034132
recombination activating gene-1 of the opossum monodelphis domestica. 19979038106
genetics of alcohol dehydrogenase and aldehyde dehydrogenase from monodelphis domestica cornea: further evidence for identity of corneal aldehyde dehydrogenase with a major soluble protein.a didelphid marsupial, the gray short-tailed opossum (monodelphis domestica), was used as a model species to study the biochemical genetics of alcohol dehydrogenases (adhs) and aldehyde dehydrogenase (aldh) in corneal tissue. isoelectric point variants of corneal aldh (designated aldh3) and a major soluble protein in corneal extracts were observed among eight families of animals used in studying the genetics of these proteins. both phenotypes exhibited identical patterns following page-ief and w ...19902272517
reflexes, fictive respiration and cell division in the brain and spinal cord of the newborn opossum, monodelphis domestica, isolated and maintained in vitro.1. the entire central nervous system (cns) was isolated from 1- to 4-day-old newborn south american opossums (monodelphis domestica). at this stage the cns has only an embryonic forebrain (two-layered) and no cerebellum and corresponds to a 14-day rat embryo. its eyes, ears and hind-limbs are only at an early stage of formation. the isolated cns preparations continue to develop and to produce electrical signals for up to 4 days in oxygenated krebs' fluid at 23 degrees c. 2. the longitudinal axis ...19902230634
characterization and distribution of estrogen receptors in the diencephalon of the gray short-tailed opossum.the brazilian gray short-tailed opossum is a pouchless marsupial whose young are born sexually undifferentiated making this animal ideal for developmental studies. previously, etgen and fadem (dev. brain res., 49 (1989) 131-133; gen. comp. endocrinol., 66 (1987) 441-446) detected estrogen receptor (er) in the hypothalamus-preoptic area, and compared males and females in the adult and during development. in this study we characterized the er and determined its distribution in specific diencephali ...19912015504
ontogeny of androgen receptor-like immunoreactivity in the reproductive tract of male monodelphis domestica.the distribution of nuclear androgen receptor-like immunoreactivity was studied in the reproductive tract of the developing and adult gray short-tailed brazilian opossum (monodelphis domestica), using the well-characterized rabbit polyclonal androgen receptor antibody, pg21. androgen receptor-like immunoreactivity was first detected on the fifth day of postnatal age, in the mesenchymal tissues of the ductus deferens, gubernaculum testis, inguinal, and scrotal areas; the urogenital sinus; and the ...19979096865
nonshivering thermogenesis in marsupials: absence of thermogenic response to beta 3-adrenergic agonists.the status of nonshivering thermogenesis (nst) in marsupials remains controversial. although morphological studies have failed to find evidence for the presence of brown adipose tissue (bat) in adults or juveniles of species from all extant families of marsupial, a number of studies have investigated the metabolic response of marsupials to noradrenaline (na) and yielded conflicting results. in eutherian mammals, na stimulates nst in bat by acting on beta 3-receptors, and in the experiments repor ...19979172391
novel strategies for eutherian x marsupial somatic cell hybrids: mapping the genome of monodelphis domestica.two hundred thirty-seven independent somatic cell hybrids have been obtained between opossum (monodelphis domestica) splenocytes, bone marrow cells, or primary fibroblasts, and hprt-deficient or tk-deficient chinese hamster, mouse, american mink, or common vole fibroblast lines. because extreme segregation and fragmentation of marsupial chromosomes commonly occurs in eutherian x marsupial somatic cells hybrids, we developed a rapid primary screening method that enables the identification of prim ...19979186503
characterization of a marsupial sperm protamine gene and its transcripts from the north american opossum (didelphis marsupialis).a synthetic oligonucleotide primer, designed from marsupial protamine protein-sequence data [balhorn, r., corzett, m., matrimas, j. a., cummins, j. & faden, b. (1989) analysis of protamines isolated from two marsupials, the ring-tailed wallaby and gray short-tailed opossum, j. cell. biol. 107] was used to amplify, via the polymerase chain reaction, protamine sequences from a north american opossum (didelphis marsupialis) cdna. using the amplified sequences as probes, several protamine cdna clone ...19938344286
localization of cells containing estrogen receptor-like immunoreactivity in the brazilian opossum brain.the brazilian opossum (monodelphis domestica) is a small, pouchless marsupial whose young are born in an immature, sexually undifferentiated state. etgen and fadem, and handa and coworkers have biochemically detected and characterized estrogen receptors in the forebrain of the brazilian opossum. in this study, we have examined the distribution of estrogen receptor-like immunoreactive (er-li) cells in the brains of gonadectomized male and female brazilian opossums using abbott h222 rat monoclonal ...19911855151
ontogeny of cells containing estrogen receptor-like immunoreactivity in the brazilian opossum brain.in this study, we have used the brazilian short-tailed opossum (monodelphis domestica) as a model to study the ontogeny of estrogen receptors in the mammalian brain. monodelphis is a small, pouchless marsupial which breeds well under laboratory conditions and whose young are born in an immature sexually undifferentiated state. the abbott h222 monoclonal rat estrogen receptor antibody (gift of abbott laboratories) was utilized in an indirect immunohistochemical procedure to detect estrogen recept ...19911790590
monodelphis domesticus: a model for early developmental wound healing.fetuses heal significantly differently than adults; amniotic fluid and the fetal environment have profound effects on the fetus' response to excisional wounding. the brazilian gray short-tailed opossum (monodelphis domesticus) is presented as a new model for early developmental wound healing. this is a small, docile, pouchless marsupial whose young, at birth, are equivalent to an 8-week gestational age human, which allows investigations of early developmental wound healing exclusive of the amnio ...19911772223
procedures for whole-mount immunohistochemistry and in situ hybridization of immature mammalian cns.whole-mount labeling techniques for staining in invertebrates or lower vertebrates cannot simply be applied to the mammalian central nervous system (cns) because of its large size. such techniques if possible would offer advantages over conventional methods based on sections since an immediate and 3-dimensional view of the stained components in a transparent cns is provided. it thereby becomes possible to survey and count large number of cells and fibers in their natural relationships. the aim o ...19989473657
hindiii rflp for nras in monodelphis domestica. 19911684857
the differentiation of the skin and its appendages. i. normal development of papillary ridges.in the present study, the normal development of papillary ridges was studied in the volar pads of both fore and hindpaws of the opossum, monodelphis domesticus. at birth, the developmental state of the opossum's paws is equivalent to that of a six-week human embryo. the development of papillary ridges in the opossum occurs entirely postnatally and the hindpaw lags behind the forepaw by at least four days in most developmental parameters. papillary ridge formation is preceded by four events: skin ...19921554108
uv-induced melanoma cell lines and their potential for proteome analysis: a review.we have established cell lines from benign cutaneous melanocytic lesions and from melanoma-affected lymph nodes of monodelphis domestica, the laboratory opossum (a south american marsupial now widely maintained in captive colonies for experimental purposes). unlike melanoma cell lines currently available from humans and other mammals, the opossum lines are derived from cells transformed in vivo by experimentally controlled exposure to ultraviolet b (uvb) radiation of known spectral composition. ...19989723165
specific chromosomal defects associated with ultraviolet radiation-induced cutaneous tumors in monodelphis domestica (marsupialia, mammalia).cytogenetic analysis of eight ultraviolet radiation (uvr)-induced cutaneous tumors and one spontaneously transformed fibroblast cell line of monodelphis domestica showed that two of the tumor cell lines were of murine origin and that the remaining six marsupial tumor cell lines had hyperdiploid stemline numbers ranging from 21 to 31. each tumor cell line showed structural and numerical abnormalities. the single transformed fibroblast cell line also showed a hyperdiploid chromosome number with st ...19921486565
evidence that cortical granule formation is a periovulatory event in marsupials.formation of cortical granules was examined in superovulated oocytes from three marsupial species, brushtail possums (trichosurus vulpecula) tammar wallabies (macropus eugeniii) and grey short-tailed opossums (monodelphis domestica) and in oocytes obtained during natural cycles in macropus eugenii. superovulation was induced by pregnant mares' serum gonadotrophin/gonadotrophin-releasing hormone (pmsg/gnrh) protocols and natural ovulation by removal of pouch young. oocytes were collected after ov ...19921404089
marsupial light chains: complexity and conservation of lambda in the opossum monodelphis domestica.the ig lambda chains in the south american opossum, monodelphis domestica, were analyzed at the expressed cdna and genomic organization level, the first described for a nonplacental mammal. the v lambda segment repertoire in the opossum was found to be comprised of at least three diverse v lambda families. each of these families appears to be related to distinct v lambda families present in placental mammals, suggesting the divergence of these genes before the separation of metatherians and euth ...19989862702
energetics of offspring production: a comparison of a marsupial (monodelphis domestica) and a eutherian (mesocricetus auratus).this study compares the energetic cost of reproduction during gestation and lactation of a eutherian, the golden hamster (mesocricetus auratus), and a similar-sized (60,120 g) marsupial, the gray short-tailed opossum (monodelphis domestica). food consumption was monitored in 20 reproductively active (ra) opossums and 16 ra hamsters from conception to weaning at equivalent intervals in 19 non-reproductive (nr) opossums and 21 nr hamsters, all maintained within their zone of thermoneutrality (30 d ...199910093907
epidermal urocanic acid and suppression of contact hypersensitivity by ultraviolet radiation in monodelphis domestica.a single specific epidermal photoreceptor for the immunosuppressive action of uv radiation has not been defined, although separate evidence is accruing in favour of each of two candidates, trans-urocanic acid and dna. in monodelphis domestica, specific photoreactivation repair of uv radiation-induced pyrimidine dimers has been shown to abrogate the suppression of contact hypersensitivity (chs), thus suggesting that dna is the target for this impairment. however, the both haired and hairless mice ...19968620096
identification of evolutionary conserved regulatory sequences in the 5' untranscribed region of the neural-specific ubiquitin c-terminal hydrolase (pgp9.5) gene.the structure at the 5' end of the gene encoding neural-specific protein gene product 9.5 (pgp9.5) has been compared between two evolutionary distant species: the human and monodelphis domestica. in contrast to the highly conserved coding sequences of the gene, only a 48% identity was found across a 1-kb stretch of 5' untranslated and untranscribed dna. promoter function studies performed on the human sequence identified a 233-bp cpg-rich minimal promoter. truncation mutagenesis revealed the pre ...19968522974
development of motoneurons and primary sensory afferents in the thoracic and lumbar spinal cord of the south american opossum monodelphis domestica.the postnatal development of the primary sensory afferent projection to the thoracic (t4) and lumbar (l4) spinal cord of the marsupial species monodelphis domestica was studied by using anterograde and retrograde neuronal tracers. large numbers of primary afferents and motoneurons were labelled by application of the carbocyanine dye dii into individual dorsal root ganglia (drg) afferents in short-term organ cultures. dorsal root axons had entered the cord at birth, but most primary afferent inne ...199910531537
localization of the 5-ht1a receptors in the brain of opossum monodelphis domestica.this paper describes the distribution of 5-ht1a receptors in the brain of opossum monodelphis domestica. they were visualized by immunohistological staining with an antibody against the amino acid sequence (170-186) of this receptor that was previously successfully used in the rat and monkey. as in eutherians, high levels of immunostaining were present in the septum, hippocampus, raphe nuclei and some other brain stem nuclei. neocortex, several thalamic nuclei and hypothalamus showed moderate de ...199910574559
isolation and comparison of the igm heavy chain constant regions from australian (trichosurus vulpecula) and american (monodelphis domestica) marsupials.cdnas encoding igm heavy chain constant region (cmu) were isolated from two metatherians (marsupials)--the australian common brushtail possum (trichosurus vulpecula) and the south american grey short-tailed opossum (monodelphis domestica). analysis of the sequences suggested that they correspond to the secreted form of cmu in both species. the domain size and structure of the marsupial cmu sequences were compared with other cmu sequences and a high degree of conservation throughout vertebrate ev ...199910579393
distribution of unipolar brush cells and other calretinin immunoreactive components in the mammalian cerebellar cortex.we have compared the distribution of unipolar brush cells (ubcs) in the cerebellum of brazilian opossum (monodelphis domestica), mouse, guinea pig, rabbit, cat, and rhesus monkey, using an antiserum to calretinin which is present in those cells. the morphology and calretinin staining intensity of the ubcs remains constant across species. as a general trend, in all species studied, ubcs are particularly enriched in the vestibulocerebellum. interspecies differences, however, were noted in the dist ...199910590511
allelic expression of igf2 in marsupials and birds.genomic imprinting, the parent-of-origin- specific expression of genes, has been observed in a variety of eutherian mammals. one gene that has been shown to be imprinted in all eutherians examined is the igf2 gene. this gene encodes a potent fetal-specific growth factor that is expressed almost exclusively from the paternal chromosome. several other imprinted genes in the igf2 pathway are imprinted as well, suggesting that igf2 is a focal point for the selective pressure leading to imprinted gen ...200010603082
injection of a boar sperm factor causes calcium oscillations in oocytes of the marsupial opossum, monodelphis domestica.at fertilisation, the sperm triggers an abrupt and transient increase in intracellular calcium ([ca2+]i) in the oocyte cytoplasm. in eutherian mammals, oocytes exhibit multiple [ca2+]i transients which are necessary for egg activation. we investigated [ca2+]i in the marsupial opossum, monodelphis domestica. embryo development in this therian mammal is quite distinct from that in most eutheria. oestrus was induced in an adult female opossum by introduction of a male into her cage. injection of a ...199910717944
ontogeny of oxytocin-like immunoreactivity in the brazilian opossum brain.the neuropeptide oxytocin (ot) has been shown to function as a neurotransmitter and/or neuromodulator in addition to its hormonal function in the periphery in the adult central nervous system (cns). previously, we have studied the postnatal neurogenesis of the paraventricular and supraoptic nuclei and ontogeny of arginine vasopressin-like immunoreactivity in the brazilian opossum brain, monodelphis domestica. in this study, we have described the ontogeny of oxytocin-like immunoreactivity (ot-ir) ...19958719325
ontogeny of cholecystokinin binding sites in the hindbrain of the laboratory rat.studies in our laboratory have revealed a robust, transient expression of cholecystokinin binding sites in the facial motor nucleus during development in the brazilian opossum, monodelphis domestica. to investigate the ubiquity of this phenomenon, we have performed receptor autoradiography on the hindbrains of embryonic and neonatal rat pups. cholecystokinin binding sites are present at very low levels in the embryonic day-16 rat hindbrain, but binding sites are abundant prior to birth. the grea ...19968724646
development of olfactory glomeruli: temporal and spatial interactions between olfactory receptor axons and mitral cells in opossums and rats.mitral cells are the primary output neurons of the vertebrate olfactory bulb and are major recipients of sensory input from the periphery. the morphogenesis of mitral cell dendrites was followed to elucidate their early spatial and temporal interactions with olfactory receptor neurons and glia during the construction of olfactory glomeruli. monodelphis domestica, a marsupial born at an extremely immature stage, and rats were examined. mitral cells were retrogradely labeled by application of the ...19968725290
cloning of the mhc class ii drb cdna from the brushtail possum (trichosurus vulpecula).the cell-surface glycoproteins encoded by the major histocompatibility complex (mhc) bind to processed foreign antigens and present them to t lymphocytes. two classes of mhc molecules and their corresponding gene sequences have been extensively studied in eutherian mammals and birds, but data on the marsupial mhc are limited. marsupials split from eutherian mammals about 125 million years ago and represent a distinct branch in mammalian evolution. here the cdna cloning of mhc class ii genes of t ...200111222910
evidence for extended action of gonadal hormones on the organization of sexually dimorphic behavior and morphology in gray short-tailed opossums (monodelphis domestica).male and female gray short-tailed opossums were gonadectomized (gdx), or treated with the estrogen receptor antagonist tamoxifen citrate (tx), or corn oil (oil) (control) during the 5th postnatal week, a time period equivalent to the 3rd postnatal week in rats and associated with high levels of circulating gonadal hormones and neural aromatase activity in this marsupial species. in adulthood following gonadectomy (for animals not previously gonadectomized) and replacement therapy with estradiol ...200111243739
characterisation of the kappa light chain of the brushtail possum (trichosurus vulpecula).two full length cdna sequences encoding the kappa light chain of the australian marsupial, trichosurus vulpecula, the brushtail possum, were isolated from a mesenteric lymph node cdna library. the constant regions (ckappa) of the two light chains were identical, but the variable (vkappa) and joining (jkappa) regions were different. at the amino acid level, possum ckappa was most similar to ckappa of an american marsupial, monodelphis domestica (75%), with similarity to eutherian ckappa ranging f ...200111292532
subclasses of vomeronasal receptor neurons: differential expression of g proteins (gi alpha 2 and g(o alpha)) and segregated projections to the accessory olfactory bulb.differential expression of g proteins (gi alpha 2 and g(o alpha) and the separate central projections of gi alpha 2- and g(o alpha)-immunoreactive (ir) vomeronasal receptor neurons were investigated in the mouse and rat using immunocytochemical methods. in the vomeronasal organ (vno), receptor neurons with their cell bodies located in the middle layer (middle 1/3) of the vomeronasal sensory epithelium express gi alpha 2. axons of these gi alpha 2-ir neurons can be followed from vno to the anteri ...19968782871
topography of muscle spindles and golgi tendon organs in shoulder muscles of "monodelphis domestica".the topography of muscle spindles and golgi tendon organs in the rotator cuff and surrounding shoulder muscles of a small laboratory marsupial (monodelphis domestica) were studied using light microscopy of serial sections. the shoulder joint of monodelphis has a large degree of freedom of movement allowing this animal to use the upper extremities for a wide range of activities like climbing and manipulating food. thus, similar to the situation in man the shoulder joint is mainly secured by muscl ...200111396793
karyotype relationships between distantly related marsupials from south america and australia.reciprocal chromosome painting and g-banding were used to compare the karyotypes of three australian marsupials (sminthopsis crassicaudata, macropus eugenii, trichosurus vulpecula) and one south american marsupial (monodelphis domestica). the results revealed only a limited number of rearrangements between these species and that the four karyotypes can be described as different combinations of fifteen conserved segments. five chromosomes are totally conserved between m. domestica (pairs 1, 2, 5, ...200111419794
immunohistochemical demonstration of adenohypophyseal hormones during postnatal ontogenesis in the gray short-tailed opossum, monodelphis domestica (marsupialia).antibodies against human fsh, lh, tsh, acth, gh, prl, and msh were applied to paraffin sections of newborn (< 1) and pouch-young individuals with the age of 1, 2, 3, 4, 5, 6, 7, 8, 10, 11, 13, 14 days, respectively (d1, d2,...). in the pouch-young, the antibody reactions occurred only in the pars distalis of the adenohypophysis. the d < 1 individuals included, the reactions were strong for acth, moderate/strong for gh, and moderate for msh. reactivity for tsh was recorded first in d2 specimens, ...19958835137
permeability and route of entry for lipid-insoluble molecules across brain barriers in developing monodelphis domestica.1. we have studied the permeability of blood-brain barriers to small molecules such as [(14)c]sucrose, [(3)h]inulin, [(14)c]l-glucose and [(3)h]glycerol from early stages of development (postnatal day 6, p6) in south american opossums (monodelphis domestica), using a litter-based method for estimating steady-state cerebrospinal fluid (csf)/plasma and brain/plasma ratios of markers that were injected i.p. 2. steady-state ratios for l-glucose, sucrose and inulin all showed progressive decreases du ...200111691876
animal models of ultraviolet radiation (uvr)-induced cutaneous melanoma.the incidence of cutaneous melanoma continues to increase in many parts of the world including the united states. the american cancer society predicts that there will be approximately 53,600 new cases of melanoma in the united states during 2002 and that there will be 7,400 deaths from melanoma during the same time period. increased understanding of the underlying mechanisms and risk factors involved in the induction of this deadly disease will require the use of suitable animal models of melano ...200212045011
the cerebellum at birth in therian mammals, with special reference to rodents.the stage of cerebellar development at birth was assessed in 23 species of placental mammals. serial histological sections were examined and five stages in the differentiation of the cerebellar cortical layers were defined. a wide diversity of conditions at birth was found. the available evidence (after parsimony reconstruction) suggests that the last common ancestor of placentals was born with an altricial cerebellum in which the molecular layer was just present between the external granular la ...200212119530
the critical period for repair of cns of neonatal opossum (monodelphis domestica) in culture: correlation with development of glial cells, myelin and growth-inhibitory molecules.a comparison was made of neurite growth across spinal cord lesions in the isolated central nervous system (cns) of newborn opossums (monodelphis domestica) at various stages of development. the aim was to define the critical period at which growth after injury ceases to occur, with emphasis on growth-inhibitory proteins, myelin and glial cells. in postnatal opossums 3-6 days old (p3-6), repair was observed 5 days after lesions were made in culture at the cervical level (c7) by crushing with forc ...19958542069
species differences in the ovarian distribution of 3beta-hydroxysteroid dehydrogenase/delta5-->4 isomerase (3beta-hsd) in two marsupials: the brushtail possum trichosurus vulpecula and the grey, short-tailed opossum monodelphis domestica.the ovarian distribution of the steroidogenic enzyme 3beta-hydroxysteroid dehydrogenase/delta(5-->4) isomerase (3beta-hsd) was investigated by immunocytochemistry in two marsupial species throughout the reproductive cycle, using a rabbit polyclonal antibody raised against human placental 3beta-hsd. in the polyoestrous and polyovular south american opossum monodelphis domestica, immunostaining was positive for 3beta-hsd in the adrenal cortex, the ovarian interstitial tissue, the corpus luteum and ...200312622697
ontogeny of arginine vasopressin-like immunoreactivity in the brazilian opossum brain.the neuropeptide arginine vasopressin is involved in many centrally mediated functions and brain development. in this study, we have examined the ontogeny of arginine vasopressin-like immunoreactivity (avp-ir) in the brazilian opossum (monodelphis domestica) brain to further understand the involvement of avp in the forming central nervous system. monodelphis is a small pouchless marsupial and its pups are born in an extremely immature state before neurogenesis is completed. in the adult brain, c ...19958575082
why does the central nervous system not regenerate after injury?spinal cord injuries in humans and in other mammals are never followed by regrowth. in recent years, considerable progress has been made in analyzing mechanisms that promote and inhibit regeneration. the focus of this review is changes that occur in the transition period in development when the central nervous system (cns) changes from being able to regenerate to the adult state of failure. in our experiments we have used the neonatal opossum (monodelphis domestica), which corresponds to a 14-da ...199910416756
mapping the distribution of the interstitial telomeric (ttaggg)n sequences in eight species of brazilian marsupials (didelphidae) by fish and the correlation with constitutive heterochromatin. do its represent evidence for fusion events in american marsupials?the c-band pattern and the distribution of the (ttaggg)(n) sequence after fluorescence in situ hybridization (fish), were studied in eight species of didelphidae marsupials: four species with 2n = 14 (marmosops parvidens, marmosops incanus, marmosa murina and metachirus nudicaudatus), two species with 2n = 18 (monodelphis domestica and m. americana), and two with 2n = 22 (didelphis marsupialis and lutreolina crassicaudata). the hybridization signals were observed at both termini telomeres of all ...200212826754
ultrastructural study of ensheathing cells in early development of olfactory axons.ultrastructural observations in the grey short-tailed opossum (monodelphis domestica) and rat revealed that ensheathing cells were intimately related to the early formation of olfactory axons. whilst the axons were still in the olfactory epithelium, they were enveloped by ensheathing cell processes which formed a cradle-like structure on the basal side of the epithelium. continued downgrowth of the axons towards the lamina propria resulted in an evagination with the ensheathing cell process or c ...19968873986
photorepair of ultraviolet radiation (uvr)-induced pyrimidine dimers in lens epithelial dna of monodelphis domestica.the repair of uv radiation-induced pyrimidine dimers has been measured in lens epithelial dna of the marsupial monodelphis domestica using a pyrimidine dimer-specific 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 ...19979066292
development of the anterior commissure in the opossum: midline extracellular space and glia coincide with early axon decussation.while the anterior commissure has been shown to be an important route of information transfer in the forebrain, relatively little is known about its anatomical development. glial substrates and extracellular spaces have been associated with the maturation of other large-fiber tracts, such as the corpus callosum and retinofugal pathway. the present study examined early stages in the maturation of the commissure in the gray short-tailed opossum, monodelphis domestica. monodelphis offspring are bor ...19979087892
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