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Monodelphis Domestica (Monodelphi + domestica)
Selected AbstractsEmx3 is required for the differentiation of dorsal telencephalic neuronsDEVELOPMENTAL DYNAMICS, Issue 8 2009Gudrun Viktorin Abstract emx3 is first expressed in prospective telencephalic cells at the anterior border of the zebrafish neural plate. Knockdown of Emx3 function by morpholino reduces the expression of markers specific to dorsal telencephalon, and impairs axon tract formation. Rescue of both early and late markers requires low-level expression of emx3 at the one- or two-somite stage. Higher emx3 expression levels cause dorsal telencephalic markers to expand ventrally, which points to a possible role of emx3 in specifying dorsal telencephalon and a potential new function for Wnt/beta-catenin pathway activation. In contrast to mice, where Emx2 plays a major role in dorsal telencephalic development, knockdown of zebrafish Emx2 apparently does not affect telencephalic development. Similarly, Emx1 knockdown has little effect. Previously, emx3 was thought to be fish-specific. However, we found all three emx orthologs in Xenopus tropicalis and opossum (Monodelphis domestica) genomes, indicating that emx3 was present in an ancestral tetrapod genome. Developmental Dynamics 238:1984,1998, 2009. © 2009 Wiley-Liss, Inc. [source] Early differentiation and migration of cranial neural crest in the opossum, Monodelphis domesticaEVOLUTION AND DEVELOPMENT, Issue 2 2003Janet L. Vaglia SUMMARY Marsupial mammals are born at a highly altricial state. Nonetheless, the neonate must be capable of considerable functional independence. Comparative studies have shown that in marsupials the morphogenesis of many structures critical to independent function are advanced relative to overall development. Many skeletal and muscular elements in the facial region show particular heterochrony. Because neural crest cells are crucial to forming and patterning much of the face, this study investigates whether the timing of cranial neural crest differentiation is also advanced. Histology and scanning electron microscopy of Monodelphis domestica embryos show that many aspects of cranial neural crest differentiation and migration are conserved in marsupials. For example, as in other vertebrates, cranial neural crest differentiates at the neural ectoderm/epidermal boundary and migrates as three major streams. However, when compared with other vertebrates, a number of timing differences exist. The onset of cranial neural crest migration is early relative to both neural tube development and somite formation in Monodelphis. First arch neural crest cell migration is particularly advanced and begins before any somites appear or regional differentiation exists in the neural tube. Our study provides the first published description of cranial neural crest differentiation and migration in marsupials and offers insight into how shifts in early developmental processes can lead to morphological change. [source] Changes in the oviducal epithelium during the estrous cycle in the marsupial Monodelphis domesticaJOURNAL OF ANATOMY, Issue 4 2007Annetrudi Kress Abstract The Monodelphis oviduct can be divided into four anatomical segments: preampulla (comprising fimbriae and infundibulum), ampulla, isthmus with crypts and uterotubal junction. Ovaries are enclosed in a periovarial sac, the bursa, and in some specimens tubules of an epoophoron could be identified. In both structures non-ciliated cells develop small translucent vesicles, which accumulate in the cell apices and presumably produce fluid as often seen in the bursa and in the tubules of the epooophoron. These vesicles do not stain with Alcian blue or PAS. The same applies also to the non-ciliated cells of the fimbriae. The oviducal epithelium of ampulla and the surface epithelium of the isthmus consisting of ciliated and non-ciliated, secretory cells undergo considerable changes during the estrous cycle. Proestrus shows low numbers of ciliated cells, some are in the process of neo-ciliogenesis, non-ciliated cells carry solitary cilia and few remnant secretory granules from the previous cycle may be found. At estrus the amount of ciliated cells in ampulla and isthmus has increased, most non-cililated cells lost the solitary cilia, developed longer microvilli and formed numerous secretory granules in their cell apices. At postestrus secretory products, often surrounded by membranes, are extruded into the oviducal lumen and contribute towards egg coat formation. First signs of deciliation processes are apparent. Solitary cilia reappear. At metestrus only few secretory cells are left with some secretory material. The lumen is often filled with shed cilia and cell apices. Proliferation of basal bodies within non-secretory cells indicate the formation of new ciliated cells. The non-ciliated epithelial cells of the isthmic crypts form no secretory granules but accumulate a great number of translucent vesicles, which in contrast to the secretory granules do not stain with Alcian blue or PAS. [source] Ultrastructure of the placenta of the tammar wallaby, Macropus eugenii: comparison with the grey short-tailed opossum, Monodelphis domesticaJOURNAL OF ANATOMY, Issue 2 2002Claudia Freyer Abstract The ultrastructure of the tammar placenta was studied throughout pregnancy. The uterine epithelium grows from a columnar to an enlarged, undulating epithelium between early gestation and mid-gestation when the shell coat that surrounds the marsupial conceptus ruptures. Trophectoderm and uterine epithelium do not form syncytia, nor does invasion of the endometrium occur at any stage of pregnancy. Uterine secretion is provided to both the bilaminar and the trilaminar side of the yolk sac placenta up to birth. Fenestrations, abundant vesicles and lumenal processes of maternal capillaries, as well as deep basal folds of the uterine epithelium, suggest that there is transfer of hemotrophes adjacent to both parts of the yolk sac. In contrast, in the grey short-tailed opossum, these structures are lacking. The yolk sacs of adjacent embryos fuse to form a common yolk sac cavity, thus losing most of the bilaminar yolk sac. The bilaminar and trilaminar components of the yolk sac placenta of the tammar are less different in structure and function than those of the grey short-tailed opossum, but both types are fully functional placentas. The extended secretory phase of the tammar uterus and the maternal recognition of early pregnancy appear to be derived characters of macropodid marsupials. [source] Early ontogeny and placentation of the grey short-tailed opossum, Monodelphis domestica (Didelphidae: Marsupialia): contribution to the reconstruction of the marsupial morphotypeJOURNAL OF ZOOLOGICAL SYSTEMATICS AND EVOLUTIONARY RESEARCH, Issue 3 2001Zeller This study provides new findings on the placenta of Monodelphis domestica and a reconstruction of the marsupial morphotype. To achieve this, early ontogeny and placentation of the grey short-tailed opossum, M. domestica, from 3 h after copulation until birth (day 15), were studied and compared with other mammals. Both the ultrastructure and histochemistry of egg membranes, foetal membranes, oviduct and uterus were examined. The results of this study provide the first detailed ultrastructural description of a trophoblastic syncytium in a marsupial. In addition, this is the first original documentation of an invasive trophectoderm and an inflammatory reaction at parturition in M. domestica. These findings were compared with literature data and included into the reconstruction of the marsupial morphotype. Based on marsupial phylogeny as proposed by Luckett (J. Mammal. Evol. 2, 255,283, 1994), characters that are consistent at least within didelphids and dasyurids were determined to be characters of the marsupial morphotype. These characters are a central yolk separated from the peripheral yolk-poor cytoplasm in the unfertilized oocyte, the presence of a zona pellucida, a mucoid coat and a shell coat, the absence of a corona radiata, oviductal mucoid secretion, no shell secretion distal to the isthmus of the oviduct, uterine shell secretion, a short tubal passage (1 day at maximum), the apposition of blastomeres to the zona pellucida prior to intercellular association, the absence of a morula stage, the polarity of the zygotic yolk, the localized segmentation of deutoplasm (yolk) during the first cleavage and subsequent extrusion of yolk vesicles during the first two cleavage stages. With regard to the marsupial morphotype, the non-polarized yolk distribution in the zygote [Hartman (J. Morphol. 27, 1,84, 1916); McCrady (Am. Anat. Mem. 16, 1,233, 1938)] is a derived character of Didelphis virginiana. Didelphis virginiana [Hartman (J. Morphol. 27, 1,84, 1916); Hartman (J. Morphol. 32, 1,139, 1919); McCrady (Am. Anat. Mem. 16, 1,233, 1938)] and Didelphis marsupialis (Hill, Q. J. Micr. Sci. 63, 91,139, 1918) share the synapomorphous reduction of deutoplasmolysis to a generalized extrusion of vesicles. The absence of separated yolk and consequently a cleavage without yolk extrusion (Renfree and Lewis, Reprod. Fert. Dev. 8, 725,742, 1996) are apomorphies of macropodids. This is possibly correlated with the association of blastomeres in early cleavage stages (Renfree and Lewis, Reprod. Fert. Dev. 8, 725,742, 1996). A yolk sac placenta and a vascularized allantochorion can be assumed for part of the ontogeny in the marsupial morphotype, irrespective of the formation of an allantoic placenta at near term stages. The character polarization of the mode of placentation and parturition needs further investigation. Frühe Ontogenie und Plazentation der grauen Hausspitzmausbeutelratte, Monodelphis domestica (Didelphidae: Marsupialia): Ein Beitrag zur Rekonstruktion des Grundplans der Marsupialia Die vorliegende Arbeit beschreibt die frühe Ontogenese und Plazentation von 3 Stunden nach der Kopulation bis zur Geburt der Beutelratte Monodelphis domestica. Es wird die Ultrastruktur und Histochemie der Eihäute, der Fetalmembranen, des Oviductes und des Uterus beschrieben. Erstmalig wird die Ultrastruktur eines trophoblastischen Syncytiums bei einem Beuteltier beschrieben. Weiterhin wird ein invasives Trophektoderm und eine Entzündungsreaktion zum Zeitpunkt der Geburt bei M. domestica festgestellt. Die Befunde dieser Studie und Literaturdaten werden verglichen und in eine Grundplanrekonstruktion integriert. Merkmale, die mindestens zwischen Vertretern der Didelphidae und Dasyuridae übereinstimmen, werden basierend auf dem phylogenetischen System der Marsupialia nach Luckett, J. Mammal. Evol. 2, 255,283, 1994, für den Grundplan der Marsupialia angenommen. Diese Merkmale sind zentral separierter Dotter und peripheres dotterarmes Zytoplasma in der unbefruchteten Eizelle, das Vorhandensein von Zona pellucida, Mucoidschicht und Schalenhaut, das Fehlen einer Corona radiata, die Mucoidsekretion durch den Oviduct, die Schalensekretion durch den Uterus und nicht distal der Isthmusregion des Oviductes, eine kurze Tubenwanderung (maximal einen Tag), die Anlagerung der Blastomeren an die Zona pellucida vor der interzellulären Verbindung, das Fehlen eines Morulastadiums, die Dotterpolarität in der Zygote, die lokale Dotterabtrennung bei der ersten Teilung und die anschließende Dotterextrusion während der ersten beiden Teilungen. In Bezug auf den Grundplan der Marsupialia ist die unpolare Dotterverteilung in der Zygote ein abgeleitetes Merkmal von Didelphis virginiana. Didelphis virginiana und Didelphis marsupialis teilen als Synapomorphie die Reduktion der Deutoplasmolyse auf eine generelle Vesikelextrusion. Das Fehlen separierten Dotters in der Oocyte und die resultierende Furchung ohne Dotterextrusion [Renfree and Lewis, Reprod. Fert. Dev. 8, 725,742, 1996] ist eine Apomorphie der Macropodidae. Hiermit hängt möglicherweise die frühe Zusammenlagerung der Blastomeren zusammen [Renfree and Lewis, Reprod. Fert. Dev. 8, 725,742, 1996]. Ein vaskularisiertes Allantochorion und eine Dottersackplazenta können für einen Teil der Ontogenese im Grundplan der Marsupialia angenommen werden. Ob das Allantochorion neben der Respiration auch dem Stoffaustausch diente ist unklar. Die Lesrichtung für den Modus der Plazentation und der Geburt bedarf weiterer Untersuchungen. [source] Determination of Wavelength-Specific UV Protection Factors of Sunscreens in Intact Skin by EPR Measurement of UV-Induced Reactive Melanin RadicalPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2007Leslie Lund ABSTRACT There remains an unmet need for skin tissue-based assays for the measurement of the UVA protection and efficacy of sunscreens. Here we describe development of a novel electron paramagnetic resonance assay that uses the photogeneration of reactive melanin radical as a measure of UV light penetration to melanocytes in situ in skin. We have used areas of focal melanocytic hyperplasia in the skin of Monodelphis domestica to model the human nevus. We show that we are able to use this assay to determine the monochromatic protection factors (mPF) of research and commercial sunscreens at specific narrow wavebands of UVB, UVA and blue visible light. Both commercial sunscreens, a sun protection factor (SPF) 4 and an SPF 30 product, had mPFs in the UVB range that correlated well with their claimed SPF. However, their mPF in the UVA ranges were only about one-third of claimed SPF. This technique can be used to design and assay sunscreens with optimally balanced UVA and UVB protection. [source] Brief communication: Forelimb compliance in arboreal and terrestrial opossumsAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 1 2010Daniel Schmitt Abstract Primates display high forelimb compliance (increased elbow joint yield) compared to most other mammals. Forelimb compliance, which is especially marked among arboreal primates, moderates vertical oscillations of the body and peak vertical forces and may represent a basal adaptation of primates for locomotion on thin, flexible branches. However, Larney and Larson (Am J Phys Anthropol 125 [2004] 42,50) reported that marsupials have forelimb compliance comparable to or greater than that of most primates, but did not distinguish between arboreal and terrestrial marsupials. If forelimb compliance is functionally linked to locomotion on thin branches, then elbow yield should be highest in marsupials relying on arboreal substrates more often. To test this hypothesis, we compared forelimb compliance between two didelphid marsupials, Caluromys philander (an arboreal opossum relying heavily on thin branches) and Monodelphis domestica (an opossum that spends most of its time on the ground). Animals were videorecorded while walking on a runway or a horizontal 7-mm pole. Caluromys showed higher elbow yield (greater changes in degrees of elbow flexion) on both substrates, similar to that reported for arboreal primates. Monodelphis was characterized by lower elbow yield that was intermediate between the values reported by Larney and Larson (Am J Phys Anthropol 125 [2004] 42,50) for more terrestrial primates and rodents. This finding adds evidence to a model suggesting a functional link between arboreality,particularly locomotion on thin, flexible branches,and forelimb compliance. These data add another convergent trait between arboreal primates, Caluromys, and other arboreal marsupials and support the argument that all primates evolved from a common ancestor that was a fine-branch arborealist. Am J Phys Anthropol, 2010. © 2009 Wiley-Liss, Inc. [source] Lung Development of Monotremes: Evidence for the Mammalian MorphotypeTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 2 2009Kirsten Ferner Abstract The reproductive strategies and the extent of development of neonates differ markedly between the three extant mammalian groups: the Monotremata, Marsupialia, and Eutheria. Monotremes and marsupials produce highly altricial offspring whereas the neonates of eutherian mammals range from altricial to precocial. The ability of the newborn mammal to leave the environment in which it developed depends highly on the degree of maturation of the cardio-respiratory system at the time of birth. The lung structure is thus a reflection of the metabolic capacity of neonates. The lung development in monotremes (Ornithorhynchus anatinus, Tachyglossus aculeatus), in one marsupial (Monodelphis domestica), and one altricial eutherian (Suncus murinus) species was examined. The results and additional data from the literature were integrated into a morphotype reconstruction of the lung structure of the mammalian neonate. The lung parenchyma of monotremes and marsupials was at the early terminal air sac stage at birth, with large terminal air sacs. The lung developed slowly. In contrast, altricial eutherian neonates had more advanced lungs at the late terminal air sac stage and postnatally, lung maturation proceeded rapidly. The mammalian lung is highly conserved in many respects between monotreme, marsupial, and eutherian species and the structural differences in the neonatal lungs can be explained mainly by different developmental rates. The lung structure of newborn marsupials and monotremes thus resembles the ancestral condition of the mammalian lung at birth, whereas the eutherian newborns have a more mature lung structure. Anat Rec, 2009. © 2008 Wiley-Liss, Inc. [source] The genome of a Gondwanan mammalBIOESSAYS, Issue 11 2007Marilyn B. Renfree Australia is thought of as the home of marsupials, but South America has 60 or so species of these interesting mammals. The genome of one of these, the South American grey short-tailed opossum, Monodelphis domestica, has just been sequenced and published in June.1 The high quality 6× coverage is the first marsupial genome completed, pipping the 2× coverage of the Australian tammar wallaby at the post by half a year. The opossum genome has an unusual structure with fewer chromosomes than the human genome (9 pairs versus 23 pairs) but a longer total length (3.4 billion versus 3 billion bases). The opossum autosomes, like those of all marsupials, are extremely large but, in contrast, the X chromosome is only 76 Mb long. The opossum genome has turned up several surprises and provided critical new information on the evolution of mammalian genomes2,6. BioEssays 29:1073,1076, 2007. © 2007 Wiley Periodicals, Inc. [source] | ||||||||||||||||||||||