Delineating geographic boundaries of the woolly mouse opossums, Micoureus demerarae and Micoureus paraguayanus (Didelphimorphia: Didelphidae)

First Genomic Evidence of a Henipa-like Virus in Brazil

The viral genus Henipavirus includes two highly virulent zoonotic viruses of serious public health concern. Hendra henipavirus and Nipah henipavirus outbreaks are restricted to Australia and Southeast Asia, respectively. The Henipavirus genus comprises mostly bat-borne viruses, but exceptions have already been described as novel viruses with rodents and shrews as reservoir animals. In the Americas, scarce evidence supports the circulation of these viruses. In this communication, we report a novel henipa-like virus from opossums (Marmosa demerarae) from a forest fragment area in the Peixe-Boi municipality, Brazil, after which the virus was named the Peixe-Boi virus (PBV). The application of next-generation sequencing and metagenomic approach led us to discover the original evidence of a henipa-like virus genome in Brazil and South America and the original description of a henipa-like virus in marsupial species. These findings emphasize the importance of further studies to characterize PBV and clarify its ecology, impact on public health, and its relationship with didelphid marsupials and henipaviruses.

Species diversity of Marmosa subgenus Micoureus (Didelphimorphia, Didelphidae) and taxonomic evaluation of the white-bellied woolly mouse opossum, Marmosa constantiae

Marmosa subgenus Micoureus contains six currently recognized species, distributed from southern Belize to northern Argentina. Although recent studies have demonstrated the monophyly of the subgenus, the species have not been recently revised. Except for M. phaea, we evaluated the species diversity in this subgenus of mouse opossums using integrated morphological, morphometric and molecular data, with emphasis on M. constantiae. We used a total of 700 specimens for morphological and morphometric analyses. For phylogenetic, species delimitation, molecular variance and population structuring analyses (the latter two only for M. constantiae), we used the mitochondrial cytochrome b gene. Morphometric variation patterns were evaluated through Principal Component Analysis and Discriminant Function Analysis. Our results indicate that there are seven species in our samples. Among the species analysed morphologically, some can be discriminated by craniodental measurements and all can be discriminated through morphology. Marmosa constantiae is polyphyletic, composed of two lineages, one of which is correctly named M. budini. Marmosa constantiae (s.s.) has a well-known genetic structure, with no clear geographic structure and no consistent morphological patterns. Several records of M. demerarae in the literature correspond to M. constantiae. Marmosa demerarae may thus represent a complex formed of at least two species.

Comparative cytogenetics of some marsupial species (Didelphimorphia, Didelphidae) from the Amazon basin

We investigated the karyotype of 18 didelphid species captured at 13 localities in the Brazilian Amazon, after conventional staining, C-banding, Ag-NOR and fluorescent in situ hybridization (FISH) using the 18S rDNA probe. Variations were found in the X chromosome, heterochromatin distribution and the 18S rDNA sequence. The main variation observed was in the position of the centromere in the X chromosome of Caluromys philander Linnaeus, 1758 and Marmosa murina Linnaeus, 1758. For both species, the X chromosome showed a geographical segregation in the pattern of variation between eastern and western Brazil, with a possible contact area in the central Amazon. C-banding on the X chromosome revealed two patterns for the species of Marmosops Matschie, 1916, apparently without geographic or specific relationships. The nucleolus organizer region (NOR) of all species was confirmed with the 18S rDNA probe, except on the Y chromosome of Monodelphis touan Shaw, 1800. The distribution of this marker varied only in the genus Marmosa Gray, 1821 [M. murina Thomas, 1905 and M. demerarae Thomas, 1905]. Considering that simple NORs are seen as a plesiomorphic character, we conclude that the species Marmosa spp. and Didelphis marsupialis Linnaeus, 1758 evolved independently to the multiple condition. By increasing the sample, using chromosomal banding, and FISH, we verified that marsupials present intra- and interspecific chromosomal variations, which suggests the occurrence of frequent chromosomal rearrangements in the evolution of this group. This observation contrasts with the chromosomal conservatism expected for didelphids.

Highly conserved d-loop sequences in woolly mouse opossums Marmosa (Micoureus)

This study reports the occurrence of highly conserved d-loop sequences in the mitochondrial genome of the woolly mouse opossum genus Marmosa subgenus Micoureus (Mammalia, Didelphimorphia, Didelphidae). Sixty-six sequences of Marmosa (Micoureus) demerarae, Marmosa (Micoureus) constantiae, and Marmosa (Micoureus) paraguayanus were amplified using universal d-loop primers and virtually no genetic differences were detected within and among species. These sequences matched the control region of the mitochondrial marsupial genome. Analyses of qualitative aspects of these sequences revealed that their structural composition is very similar to the d-loop region of other didelphid species. However, the total lack of variability has not been reported from other closely related species. The data analyzed here support the occurrence of highly conserved d-loop sequences, and we found no support for the hypothesis that these sequences are d-loop-like nuclear pseudogenes. Furthermore, the control and flanking regions obtained with different primers corroborate the lack of variability of the d-loop sequences in the mitochondrial genome of Marmosa (Micoureus).