Multitemas n. As coletas ocorreram entre abril de e agosto de Revista Brasileira de Zoologia, Curitiba, v. Journal of Mammalogy, Champaing, US, v. Ecology of a small mammal community in Atlantic Forest area in southeastern Brazil.
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Abstract Background The white-eared opossum Didelphis albiventris is widely distributed throughout Brazil and South America. It has been used as an animal model for studying different scientific questions ranging from the restoration of degraded green areas to medical aspects of Chagas disease, leishmaniasis and resistance against snake venom.
As a marsupial, D. Opossum joeys are born after only 13 days, and the final stages of organogenesis occur when the neonates are inside the pouch, depending on lactation. As neither the genome of this opossum species nor its transcriptome has been completely sequenced, the use of D. In this work, we sequenced the D.
Results The D. The de novo assembly of these transcripts generated 85, transcripts. The enriched GO terms were mainly related to the immune system, blood tissue development and differentiation, vision, hearing, digestion, the CNS and limb development. Conclusions The elucidation of opossum transcriptomes provides an out-group for better understanding the distinct characteristics associated with the evolution of mammalian species.
This study provides the first transcriptome sequences and catalogue of genes for a marsupial species at different neonatal stages, allowing the study of the mechanisms involved in organogenesis. Background Marsupials are one of the three large modern groups of mammals and are considered the closest external group to eutherian mammals placentals.
They comprise a group of extant species found in the Americas, mostly in South America and Australasia [ 1 ]. The most intriguing characteristic of marsupials is related to the way they develop: after a very short period of intrauterine development, they are born with only a few early developed structures including the external nostrils, the mouth and the forelimbs , while all other structures are still in early stages of development.
In general, lactation plays a major role in the development of marsupial joeys [ 2 ], whereas the placenta is short-lived, and most marsupial placentas are either non-invasive, as in the tammar wallaby [ 3 , 4 ], or invasive in only the last few days of pregnancy, as in the South American grey short-tailed opossum [ 3 , 5 ]. In the pouch, marsupial neonates are in an altricial developmental stage equivalent to E10—12 of mouse embryos or 10 weeks of human development [ 6 ].
Marsupials can be considered an excellent model for understanding the mechanisms that govern cellular differentiation during organogenesis due their close phylogenetic relationship to eutherians and the availability of neonates in the pouch overcoming the difficulty of access when studying in utero development. For instance, different aspects of neocortex development, expansion and evolution have recently been revealed using embryos and neonates of the grey short-tailed opossum Monodelphis domestica and the tammar wallaby Macropus eugenii as models [ 13 , 14 ].
Studies using grey short-tailed opossum neonates revealed new insights into bronchioalveolar [ 15 ] and chondrocranial development in mammals [ 16 ]. Morphological and morphometric study of the skin of marsupial neonates suggested the participation of this organ in gaseous exchange on the basis of the investigation of species such as the eastern quoll Dasyurus viverrinus , grey short-tailed opossum Monodelphis domestica , southern brown bandicoot Isoodon obesulus , long-nosed bandicoot Perameles nasuta , brush-tail possum Trichosurus vulpecula , koala Phascolarctos cinereus , long-nosed potoroo Potorous tridactylus , brush-tailed rock wallaby Petrogale penicillata , red-necked pademelon Thylogale thetis and black-striped wallaby Macropus dorsalis [ 17 ].
Marsupials, especially didelphids, have been employed as models for the study of mammalian evolution [ 18 , 19 , 20 ]. The present work adds to a growing number of new marsupial genome and transcriptome datasets that have been released in the last few years, which have mainly been developed to the study of the marsupial placenta, lactation and immune system, in species such as the grey short-tailed opossum Monodelphis domestica [ 21 , 22 ], the Tasmanian devil Sarcophilus harrisii [ 23 , 24 ], the tammar wallaby Macropus eugenii [ 12 , 25 , 26 ], the koala Phascolarctos cinereus [ 27 , 28 , 29 ], the long-nosed bandicoot Perameles nasuta [ 30 , 31 ], the fat-tailed dunnart Sminthopsis crassicaudata [ 32 ], the monito del monte Dromiciops gliroides [ 33 ], and the Tasmanian tiger Thylacinus cynocephalus [ 34 ].
Based on these previous findings and genomic data availability limitations, the goal of this work was to sequence the transcriptome of the white-eared opossum Didelphis albiventris during the first days of its postnatal development. This is the first transcriptome obtained from a South American marsupial species during distinct stages of neonatal development.
For this work, we used neonates harvested at birth and at 5 and 10 days old. These marsupials are widely distributed in South America including Cerrado, Caatinga and Pantanal areas [ 38 , 39 , 40 , 41 , 42 ], and they have been used as model organisms to understand human infections such as Chagas disease [ 43 , 44 ] and leishmaniasis [ 45 ].
The seeds of many plant species including pioneers may aid in the restoration of degraded environments after they are eaten by opossums, as they remain viable after passing through the intestine [ 46 ].
They are also resistant to intoxication by millipedes [ 50 ], which are toxic to many vertebrates. Our group has been trying to establish D. This opossum exhibits complete heterodont dentition that is closer to that of humans than is that of rodents, the typical model for these studies [ 8 , 51 , 52 , 53 , 54 , 55 ].
We can characterize the morphological stages of early tooth development dental lamina, bud, cap, and bell stages in this species [ 8 , 51 , 52 , 53 , 54 , 55 ]. However, the use of sequences from M.
Analysis of the D. Results RNA-seq and transcriptome assembly of D. The analysis of all RNA-seq samples was performed; on average, over Using the Trinity tool, 85, transcripts were assembled, considering a minimum fragment overlap of 35 bp and contigs with a length of at least bp. Table 1 RNA-seq data Full size table Sequence composition among biological replicates Principal component analysis PCA showed that the biological replicates for each developmental stage could be grouped together, forming 3 distinct clusters corresponding to the different sets of biological conditions Fig.
Homogeneity of the biological triplicates determined by PCA a and the colourmap matrix b based on transcript expression values between P0, P5 and P In the colourmap matrix, the differences between the samples are indicated as follows: green dots represent the most different samples, and the red dots represent the least different samples b.
The expression levels of each transcript throughout the three developmental stages were represented as a colourmap matrix, allowing the observation that the expression of several transcripts did not change considerably across samples P0, P5 and P It was also possible to observe that some transcripts varied between the samples, showing either increasing or decreasing expression across the sample types Fig.
Differentially expressed genes between opossum postnatal stages We identified 14, differentially expressed DE transcripts between the P0, P5 and P10 biological stages. The most striking difference was observed between P0 and P10, as 11, DE transcripts were identified between these stages Fig. Additionally, transcripts were found to be DE between all analysed developmental stages Fig. The transcripts are described as exhibiting an increase or decrease in the expression level at the older stage compared to the younger stage.
Images were generated using Venny 2.
La cabeza es relativamente grande, con el hocico acuminado provisto de largas fimbrias vibrisas extremadamente sensibles al tacto. Otras dos bandas de tono similar cruzan los ojos , negros y redondos, que reflejan tonos rojizos cuando les da la luz directamente. Las orejas desnudas, estrechas y completamente negras en los adultos. La cola , con capacidad prensil es larga, de mayor longitud que el cuerpo.
Didelphis albiventris Lund, 1840