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 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
isolation and characterization of melanopsin (opn4) from the australian marsupial sminthopsis crassicaudata (fat-tailed dunnart).melanopsin confers photosensitivity to a subset of retinal ganglion cells and is responsible for many non-image-forming tasks, like the detection of light for circadian entrainment. recently, two melanopsin genes, opn4m and opn4x, were described in non-mammalian vertebrates. however, only one form, opn4m, has been described in the mammals, although studies to date have been limited to the placentals and have not included the marsupials. we report here the isolation and characterization of an opn ...200717785267
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
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