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‣ The discovery of Foxl2 paralogs in chondrichthyan, coelacanth and tetrapod genomes reveals an ancient duplication in vertebrates

Geraldo, M. T.; Valente, G. T.; Braz, A. S K; Martins, C.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 57-65
Português
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The Foxl2 (forkhead box L2) gene is an important member of the forkhead domain family, primarily responsible for the development of ovaries during female sex differentiation. The evolutionary studies conducted previously considered the presence of paralog Foxl2 copies only in teleosts. However, to search for possible paralog copies in other groups of vertebrates and ensure that all predicted copies were homolog to the Foxl2 gene, a broad evolutionary analysis was performed, based on the forkhead domain family. A total of 2464 sequences for the forkhead domain were recovered, and subsequently, 64 representative sequences for Foxl2 were used in the evolutionary analysis of this gene. The most important contribution of this study was the discovery of a new subgroup of Foxl2 copies (ortholog to Foxl2B) present in the chondrichthyan Callorhinchus milii, in the coelacanth Latimeria chalumnae, in the avian Taeniopygia guttata and in the marsupial Monodelphis domestica. This new scenario indicates a gene duplication event in an ancestor of gnathostomes. Furthermore, based on the analysis of the syntenic regions of both Foxl2 copies, the duplication event was not exclusive to Foxl2. Moreover, the duplicated copy distribution was shown to be complex across vertebrates...

‣ Ectoparasitos de roedores e marsupiais da reserva particular do Patrimônio Natural Nhumirim, no Pantanal da Nhecolândia, Corumbá, MS, Brasil

Ferreira, Rafael Penedo
Fonte: Florianópolis, SC. Publicador: Florianópolis, SC.
Tipo: Trabalho de Conclusão de Curso Formato: 40
Português
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TCC(graduação) - Universidade Federal de Santa Catarina. Centro de Ciências Biológicas. Biologia.; A maioria dos trabalhos com ectoparasitos têm sido realizados na região sudeste, principalmente nos estados do Rio de Janeiro e Minas Gerais. Os trabalhos deste tipo no Pantanal são raros e visam principalmente os mamíferos de médio e grande porte, de modo que os pequenos mamíferos ainda são subexplorados quanto à sua fauna de ectoparasitos. O objetivo deste trabalho foi realizar um levantamento de espécies ectoparasitas nos pequenos mamíferos não voadores da região sudeste do Pantanal. No período de novembro de 2011 a junho de 2012, nós encontramos 3482 artrópodes (pertencentes às ordens Siphonaptera, Phthiraptera e Acari) parasitando 97 roedores das espécies Clyomys laticeps, Holochilus chacarius, Oecomys mamorae e Thrichomys pachyurus e 26 marsupiais da espécie Monodelphis domestica. As pulgas pertenciam todas à espécie Polygenis (P.) bohlsi bohlsi e só foram encontradas em H. chacarius, T. pachyurus e M. domestica e este foi o primeiro registro da presença da mesma na região do Pantanal, assim como foi o primeiro registro desta pulga parasitando os três mamíferos supracitados. Os piolhos só foram encontrados em C. laticeps...

‣ Photoreactivation of UV-induced pyrimidine dimers and erythema in the marsupial Monodelphis domestica.

Ley, R D
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /04/1985 Português
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Post-UV treatment of the gray, short-tailed opossum Monodelphis domestica with photoreactivating light (320-400 nm) suppressed the appearance of UV-induced erythema as evidenced by an increase in the dose of UV required to elicit an erythemal response. The average erythema dose for animals held in the dark following UV exposure was 620 +/- 40 J/m2, whereas 2460 +/- 110 J/m2 were required for erythema induction with animals exposed to 90 min of photoreactivating light post-UV. Pre-UV exposure to photoreactivating light had no effect on the UV induction of erythema. The dose-response for the photoreversal of pyrimidine dimers in epidermal DNA of M. domestica was similar to that for the photoreactivation of erythema induction. These data not only support the notion that DNA is the primary chromophore involved in the induction of erythema but also identify pyrimidine dimers as the major DNA change responsible for its induction. These results also identify M. domestica as a useful whole-animal system with which to determine the role of pyrimidine dimers in other photobiological responses of mammalian skin.

‣ Albumin transfer across the choroid plexus of South American opossum (Monodelphis domestica).

Knott, G W; Dziegielewska, K M; Habgood, M D; Li, Z S; Saunders, N R
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 15/02/1997 Português
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1. Blood-cerebrospinal fluid (CSF) transfer of various exogenous albumins has been investigated in developing Monodelphis domestica (South American grey short-tailed opossum) and compared with the steady-state CSF: plasma ratios for endogenous (Monodelphis) albumin. Ratios for Monodelphis albumin and human albumin were similar and were the highest at postnatal day 5 (P5) (48.2 +/- 4.4 and 40.6 +/- 4.5%, respectively). The ratio for bovine albumin was similar to the steady-state ratio for Monodelphis albumin at P7-8 but became consistently lower than the Monodelphis albumin ratio at all other ages until P32-36 when all albumins tested attained a similar low ratio. The CSF:plasma ratio of chemically modified (succinylated) bovine albumin was always significantly lower than that of other albumins, except at the oldest age examined (P32-36). 2. Immunocytochemistry showed that within the brain, albumin was confined to the lumen and endothelial cells of blood vessels. In the choroid plexus only a small proportion (0.2-1.7% of the total cell number) of epithelial cells was positive for albumin, both endogenous and exogenous, at all ages studied (except the 3rd ventricle where cells were only positive from P8). The CSF was strongly positive for all albumins. The peak proportion of positive cells and of albumin concentrations in CSF occurred at P8. These findings suggest that the primary route for penetration of albumin into CSF is directly across the choroid plexus rather than via the brain. 3. Double-labelling immunocytochemistry revealed that the same epithelial cells contained both endogenous (Monodelphis) and exogenous (human) albumin. In contrast...

‣ Testis development in the opossum Monodelphis domestica.

Xie, Q; Mackay, S; Ullmann, S L; Gilmore, D P; Payne, A P
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /10/1996 Português
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Testis development in the grey short-tailed opossum, Monodelphis domestica, was investigated by light and electron microscopy in 180 animals. On the day of birth, half the karyotyped males were found to have histologically differentiated testes. By day (d) 1 testicular cords were clearly distinguished in all XY gonads and the tunica albuginea was fully developed. At this stage the large and pale primordial germ cells could be differentiated from dark pre-Sertoli cells. From d 3 the testis became progressively rounded and testicular cords were surrounded by peritubular cells. Leydig cells were then distinguishable by the expected ultrastructural features of steroidogenically active cells, showing abundant vesicles of SER, extensive mitochondria with tubular cristae and numerous lipid inclusions. Subsequently these cells formed clusters and were surrounded by envelope cells until wk 12. Testes were located in the abdomen, attached to the large mesonephroi, until d 24 after birth when they began their descent to the scrotal sac. From 7 wk the interstitial tissue became less cellular. At the prepubertal stage (12 wk), the seminiferous tubules lacked lumina. Leydig cell cytoplasm was electron-dense with increased amounts of SER forming parallel profiles. By 4 mo (pubertal stage)...

‣ First-generation linkage map of the gray, short-tailed opossum, Monodelphis domestica, reveals genome-wide reduction in female recombination rates.

Samollow, Paul B; Kammerer, Candace M; Mahaney, Susan M; Schneider, Jennifer L; Westenberger, Scott J; VandeBerg, John L; Robinson, Edward S
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /01/2004 Português
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The gray, short-tailed opossum, Monodelphis domestica, is the most extensively used, laboratory-bred marsupial resource for basic biologic and biomedical research worldwide. To enhance the research utility of this species, we are building a linkage map, using both anonymous markers and functional gene loci, that will enable the localization of quantitative trait loci (QTL) and provide comparative information regarding the evolution of mammalian and other vertebrate genomes. The current map is composed of 83 loci distributed among eight autosomal linkage groups and the X chromosome. The autosomal linkage groups appear to encompass a very large portion of the genome, yet span a sex-average distance of only 633.0 cM, making this the most compact linkage map known among vertebrates. Most surprising, the male map is much larger than the female map (884.6 cM vs. 443.1 cM), a pattern contrary to that in eutherian mammals and other vertebrates. The finding of genome-wide reduction in female recombination in M. domestica, coupled with recombination data from two other, distantly related marsupial species, suggests that reduced female recombination might be a widespread metatherian attribute. We discuss possible explanations for reduced female recombination in marsupials as a consequence of the metatherian characteristic of determinate paternal X chromosome inactivation.

‣ An analysis of the gene complement of a marsupial, Monodelphis domestica: Evolution of lineage-specific genes and giant chromosomes

Goodstadt, Leo; Heger, Andreas; Webber, Caleb; Ponting, Chris P.
Fonte: Cold Spring Harbor Laboratory Press Publicador: Cold Spring Harbor Laboratory Press
Tipo: Artigo de Revista Científica
Publicado em /07/2007 Português
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The newly sequenced genome of Monodelphis domestica not only provides the out-group necessary to better understand our own eutherian lineage, but it enables insights into the innovative biology of metatherians. Here, we compare Monodelphis with Homo sequences from alignments of single nucleotides, genes, and whole chromosomes. Using PhyOP, we have established orthologs in Homo for 82% (15,250) of Monodelphis gene predictions. Those with single orthologs in each species exhibited a high median synonymous substitution rate (dS = 1.02), thereby explaining the relative paucity of aligned regions outside of coding sequences. Orthology assignments were used to construct a synteny map that illustrates the considerable fragmentation of Monodelphis and Homo karyotypes since their therian last common ancestor. Fifteen percent of Monodelphis genes are predicted, from their low divergence at synonymous sites, to have been duplicated in the metatherian lineage. The majority of Monodelphis-specific genes possess predicted roles in chemosensation, reproduction, adaptation to specific diets, and immunity. Using alignments of Monodelphis genes to sequences from either Homo or Trichosurus vulpecula (an Australian marsupial), we show that metatherian X chromosomes have elevated silent substitution rates and high G+C contents in comparison with both metatherian autosomes and eutherian chromosomes. Each of these elevations is also a feature of subtelomeric chromosomal regions. We attribute these observations to high rates of female-specific recombination near the chromosomal ends and within the X chromosome...

‣ Evolutionary dynamics of transposable elements in the short-tailed opossum Monodelphis domestica

Gentles, Andrew J.; Wakefield, Matthew J.; Kohany, Oleksiy; Gu, Wanjun; Batzer, Mark A.; Pollock, David D.; Jurka, Jerzy
Fonte: Cold Spring Harbor Laboratory Press Publicador: Cold Spring Harbor Laboratory Press
Tipo: Artigo de Revista Científica
Publicado em /07/2007 Português
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The genome of the gray short-tailed opossum Monodelphis domestica is notable for its large size (∼3.6 Gb). We characterized nearly 500 families of interspersed repeats from the Monodelphis. They cover ∼52% of the genome, higher than in any other amniotic lineage studied to date, and may account for the unusually large genome size. In comparison to other mammals, Monodelphis is significantly rich in non-LTR retrotransposons from the LINE-1, CR1, and RTE families, with >29% of the genome sequence comprised of copies of these elements. Monodelphis has at least four families of RTE, and we report support for horizontal transfer of this non-LTR retrotransposon. In addition to short interspersed elements (SINEs) mobilized by L1, we found several families of SINEs that appear to use RTE elements for mobilization. In contrast to L1-mobilized SINEs, the RTE-mobilized SINEs in Monodelphis appear to shift from G+C-rich to G+C-low regions with time. Endogenous retroviruses have colonized ∼10% of the opossum genome. We found that their density is enhanced in centromeric and/or telomeric regions of most Monodelphis chromosomes. We identified 83 new families of ancient repeats that are highly conserved across amniotic lineages, including 14 LINE-derived repeats; and a novel SINE element...

‣ Evolution of mammalian CD1: marsupial CD1 is not orthologous to the eutherian isoforms and is a pseudogene in the opossum Monodelphis domestica

Baker, Michelle L; Miller, Robert D
Fonte: Blackwell Science Inc Publicador: Blackwell Science Inc
Tipo: Artigo de Revista Científica
Publicado em /05/2007 Português
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CD1 is a member of the major histocompatibility complex (MHC) class I family of proteins that present lipid antigens to T cells and natural killer (NK) T cells; it is found in both eutherian mammals and birds. In eutherians, duplication of the CD1 gene has resulted in multiple isoforms. A marsupial CD1 homologue was identified in a set of expressed sequence tags from the thymus of the bandicoot Isoodon macrourus. Southern blot and genomic sequence analyses revealed that CD1 is a single copy gene in both I. macrourus and a distantly related marsupial, the opossum Monodelphis domestica, which is currently the only marsupial species for which a whole genome sequence is available. We found that the opossum CD1 is located in a genomic region with a high degree of conserved synteny to the chromosomal regions containing human and mouse CD1. A phylogenetic analysis of mammalian CD1 revealed that marsupial CD1 is not orthologous to the eutherian CD1 isoforms, consistent with the latter having emerged by duplication after the separation of marsupials and eutherians 170–180 million years ago. The I. macrourus CD1 gene is actively transcribed and appears to encode a functional protein. In contrast, transcription of the M. domestica CD1 was not detected in any tissue and the predicted CD1 gene sequence contains a number of deletions that appear to render the locus a pseudogene.

‣ On the genomics of immunoglobulins in the gray, short-tailed opossum Monodelphis domestica

Wang, Xinxin; Olp, Jonathan J.; Miller, Robert D.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Português
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Annotated maps of the IGH, IGK, and IGL loci in the gray, short-tailed opossum Monodelphis domestica were generated from analyses of the available whole genome sequence for this species. Analyses of their content and organization confirmed a number of previous conclusions based on characterization of cDNAs encoding opossum immunoglobulin heavy and light chains and limited genomic analysis, including: i) the predominance of a single IGHV subgroup and clan; ii) the presence of a single IgG subclass; iii) the apparent absence of an IgD; and iv) the general organization and V gene complexity of the IGK and IGL light chain loci. In addition several unexpected discoveries were made including the presence of a partial germ-line joined IGHV segment, the first germline joined Ig V gene to be found in a mammal. In addition was the presence of a larger number of IGKV subgroups than had been previously identified. With this report, annotated maps of the Major Histocompatibility Complex, T cell receptor, and immunoglobulin loci have been completed for M. domestica, the only non-eutherian mammalian species for which this has been accomplished, strengthening the utility of this species as a model organism.

‣ Normal Organ Weights, Serum Chemistry, Hematology, and Cecal and Nasopharyngeal Bacterial Cultures in the Gray Short-Tailed Opossum (Monodelphis domestica)

Evans, Kristin D; Hewett, Terry A; Clayton, Cindy J; Krubitzer, Leah A; Griffey, Stephen M
Fonte: American Association for Laboratory Animal Science Publicador: American Association for Laboratory Animal Science
Tipo: Artigo de Revista Científica
Português
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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...

‣ An X chromosome MicroRNA Cluster in the Marsupial Species Monodelphis domestica

Devor, Eric J.; Huang, Lingyan; Wise, Amanda; Peek, Andrew S.; Samollow, Paul B.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
Português
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MicroRNAs (miRNAs) are an important class of posttranscriptional gene expression regulators. In the course of mapping novel marsupial-specific miRNAs in the genome of the gray short-tailed opossum, Monodelphis domestica, we encountered a cluster of 39 actual and potential miRNAs spanning 102 kb of the X chromosome. Analysis of the cluster revealed that 37 of the 39 miRNAs are predicted to form thermodynamically stable hairpins, and at least 3 members have been directly cloned from M. domestica tissues. The sequence characteristics of these miRNAs suggest that they all descended from a single common ancestor. Further, 2 distinct families appear to have diversified from the ancestral sequence through different duplication mechanisms: one through a series of simple tandem duplications and the other through a recurrent transposon-mediated duplication process.

‣ Spontaneous Development of Full Weight-Supported Stepping after Complete Spinal Cord Transection in the Neonatal Opossum, Monodelphis domestica

Wheaton, Benjamin J.; Callaway, Jennifer K.; Ek, C. Joakim; Dziegielewska, Katarzyna M.; Saunders, Norman R.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 02/11/2011 Português
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Spinal cord trauma in the adult nervous system usually results in permanent loss of function below the injury level. The immature spinal cord has greater capacity for repair and can develop considerable functionality by adulthood. This study used the marsupial laboratory opossum Monodelphis domestica, which is born at a very early stage of neural development. Complete spinal cord transection was made in the lower-thoracic region of pups at postnatal-day 7 (P7) or P28, and the animals grew to adulthood. Injury at P7 resulted in a dense neuronal tissue bridge that connected the two ends of the cord; retrograde neuronal labelling indicated that supraspinal and propriospinal innervation spanned the injury site. This repair was associated with pronounced behavioural recovery, coordinated gait and an ability to use hindlimbs when swimming. Injury at P28 resulted in a cyst-like cavity encased in scar tissue forming at the injury site. Using retrograde labelling, no labelled brainstem or propriospinal neurons were found above the lesion, indicating that detectable neuronal connectivity had not spanned the injury site. However, these animals could use their hindlimbs to take weight-supporting steps but could not use their hindlimbs when swimming. White matter...

‣ Visual acuity in the short-tailed opossum (Monodelphis domestica)

Dooley, James C.; Nguyen, Hoang; Seelke, Adele M. H.; Krubitzer, Leah
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Português
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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.

‣ Weight-Bearing Locomotion in the Developing Opossum, Monodelphis domestica following Spinal Transection: Remodeling of Neuronal Circuits Caudal to Lesion

Wheaton, Benjamin J.; Noor, Natassya M.; Whish, Sophie C.; Truettner, Jessie S.; Dietrich, W. Dalton; Zhang, Moses; Crack, Peter J.; Dziegielewska, Katarzyna M.; Saunders, Norman R.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 12/08/2013 Português
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Complete spinal transection in the mature nervous system is typically followed by minimal axonal repair, extensive motor paralysis and loss of sensory functions caudal to the injury. In contrast, the immature nervous system has greater capacity for repair, a phenomenon sometimes called the infant lesion effect. This study investigates spinal injuries early in development using the marsupial opossum Monodelphis domestica whose young are born very immature, allowing access to developmental stages only accessible in utero in eutherian mammals. Spinal cords of Monodelphis pups were completely transected in the lower thoracic region, T10, on postnatal-day (P)7 or P28 and the animals grew to adulthood. In P7-injured animals regrown supraspinal and propriospinal axons through the injury site were demonstrated using retrograde axonal labelling. These animals recovered near-normal coordinated overground locomotion, but with altered gait characteristics including foot placement phase lags. In P28-injured animals no axonal regrowth through the injury site could be demonstrated yet they were able to perform weight-supporting hindlimb stepping overground and on the treadmill. When placed in an environment of reduced sensory feedback (swimming) P7-injured animals swam using their hindlimbs...

‣ Rôle du système du trijumeau dans la locomotion chez le nouveau-né d’opossum (Monodelphis domestica)

Adadja, Thierry Ayiwanou
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Thèse ou Mémoire numérique / Electronic Thesis or Dissertation
Português
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L’opossum Monodelphis domestica naît très immature et grimpe sans aide de la mère, du sinus urogénital à une mamelle où il va s’attacher pour poursuivre son développement. Des informations sensorielles sont nécessaires pour guider le nouveau-né vers la mamelle et les candidats les plus probables sont le toucher, l’équilibre et l’olfaction. Pour tester l’action des différents systèmes sur la motricité chez l’opossum nouveau-né, des régions céphaliques du trijumeau, du vestibulaire et de l’olfaction ont été stimulées électriquement sur des préparations in vitro en comparaison avec une stimulation seuil T (intensité minimale de la stimulation à la moelle épinière cervicale induisant le mouvement des membres antérieurs). Par comparaison, un mouvement similaire était induit par des stimulations à ~2T du ganglion du trijumeau, à ~20 T du complexe vestibulaire, et à ~600 T des bulbes olfactifs. L’étude de l'innervation de la peau faciale et des voies relayant les informations du trijumeau vers la moelle épinière (ME) a été approfondie en utilisant de l’immunohistochimie pour les neurofilament-200 et du traçage rétrograde avec du Texas-Red couplé à des Dextrans Aminés. De nombreuses fibres nerveuses ont été révélées dans le derme de plusieurs régions de la tête. Quelques cellules du ganglion trigéminal projettent à la ME rostrale...

‣ Expression des cotransporteurs cation-chlorure KCC2 et NKCC1 au cours du développement de la moelle épinière de l’opossum Monodelphis domestica

Phan, Ha-Loan
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Thèse ou Mémoire numérique / Electronic Thesis or Dissertation
Português
Relevância na Pesquisa
49.020137%
L’inhibition est nécessaire à la génération d’outputs coordonnés entre muscles antagonistes lors de la locomotion. Une baisse de la concentration neuronale en ions chlorure au cours du développement des mammifères conduit à l’émergence de l’inhibition. Cette baisse repose sur l’équilibre entre deux cotransporteurs cation-chlorure, KCC2 et NKCC1. KCC2 expulse Cl- de la cellule alors que NKCC1 pompe Cl- dans la cellule. L’opossum Monodelphis domestica naît dans un état très immature. Le seul comportement locomoteur qu’il présente à la naissance consiste en des mouvements rythmiques et alternés des membres antérieurs pour grimper le long du ventre de la mère vers une tétine. Les membres postérieurs sont des bourgeons immobiles dont le développement est en grande partie postnatal. Pour cette raison, cette espèce constitue un modèle idéal pour l’étude du développement locomoteur. Afin d’étudier les mécanismes conduisant à l’émergence de l’inhibition durant le développement moteur, nous avons décrit l’expression développementale de KCC2 et NKCC1 chez l’opossum postnatal par immunohistochimie au niveau des renflements spinaux. Les motoneurones et afférences primaires ont été identifiés en utilisant un marquage rétrograde au TRDA. Le marquage pour KCC2 et NKCC1 est détecté dans la moelle épinière ventrale dans la matière grise et blanche présomptive dès la naissance...

‣ Gonadal sex differentiation in embryos and neonates of the marsupial, Monodelphis domestica: arrest of testis development in postterm embryos.

Baker, P J; Moore, H D; Burgess, A M; Mittwoch, U
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /04/1993 Português
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Growth and histological differentiation were studied in 8 litters of embryos and 4 litters of neonate grey short-tailed opossums, Monodelphis domestica. The embryonic litters included 2 that had passed their expected birth date, and whose weights exceeded the usual birthweights; we refer to these litters as 'postmature'. There was an abrupt increase in the growth rate of XY gonads after birth, but this was not seen in XX gonads. Although there was evidence of testicular differentiation in XY gonads on the day before the expected birth, testicular differentiation was found to be blocked in postmature litters. The growth of XX gonads in postmature embryos was not affected. In view of evidence that exogenous oestrogens feminise the gonads of genetic males in some species of marsupials including Monodelphis domestica, the question arises whether oestrogen is responsible for the failure of testes to continue their development in utero. We suggest that the ability of functional testes to develop in the presence of oestrogen may be a fundamental requirement distinguishing eutherian mammals from other vertebrates, including marsupials.

‣ A microsatellite-based, physically anchored linkage map for the gray, short-tailed Opossum ( Monodelphis domestica )

Samollow, Paul; Gouin, Nicolas; Miethke, Patricia; Mahaney, Susan M; Kenney, Margaret; VandeBerg, John L; Graves, Jennifer; Kammerer, C M
Fonte: Kluwer Academic Publishers Publicador: Kluwer Academic Publishers
Tipo: Artigo de Revista Científica
Português
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The genome of the gray, short-tailed opossum, Monodelphis domestica, will be the first of any marsupial to be fully sequenced. The utility of this sequence will be greatly enhanced by construction and integration of detailed genetic and physical maps. The

‣ Linkage mapping and physical localization of the major histocompatibility complex region of the marsupial Monodelphis domestica

Gouin, Nicolas; Deakin, Janine; Miska, K B; Miller, Robert D; Kammerer, C M; Graves, Jennifer; VandeBerg, John L; Samollow, Paul
Fonte: S Karger AG Publicador: S Karger AG
Tipo: Artigo de Revista Científica
Português
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We used genetic linkage mapping and fluorescence in situ hybridization (FISH) to conduct the first analysis of genic organization and chromosome localization of the major histocompatibility complex (MHC) of a marsupial, the gray, short-tailed opossum Monodelphis domestica. Family based linkage analyses of two M. domestica MHC Class I genes (UA1, UG) and three MHC Class II genes (DAB, DMA, and DMB) revealed that these genes were tightly linked and positioned in the central region of linkage group 3 (LG3). This cluster of MHC genes was physically mapped to the centromeric region of chromosome 2q by FISH using a BAC clone containing the UA1 gene. An interesting finding from the linkage analyses is that sex-specific recombination rates were virtually identical within the MHC region. This stands in stark contrast to the genome-wide situation, wherein males exhibit approximately twice as much recombination as females, and could have evolutionary implications for maintaining equality between males and females in the ability to generate haplotype diversity in this region. These analyses also showed that three non-MHC genes that flank the MHC region on human chromosome 6, myelin oligodendrocyte glycoprotein (MOG), bone morphogenetic protein 6 (BMP6)...