Small mammals in the diet of Barn Owls (Tyto furcata) in an urban area in Rio de Janeiro state, Brazil, with a new record of the dwarf mouse opossum (Cryptonanus)

Several studies emphasize the use of owl pellets in small mammal inventories in natural areas harboring high richness of rare species, but few Brazilian Atlantic forest localities have been surveyed by this method. The present study documents the species composition and abundance of small mammals in the diet of Tyto furcata in an urban area of the municipality of Campos dos Goytacazes, Rio de Janeiro, Brazil, remarking on a new record of the dwarf mouse opossum genus Cryptonanus in the Atlantic forest. We analyzed 265 pellets regurgitated by a pair of T. furcata from November 2016 to September 2017 found in a nesting box. Analysis of the samples enabled finding a total of 596 individuals of four small mammal species. Mus musculus was predominant among the prey items (98.3%), while the native rodents Necromys lasiurus (1.3%) and Holochilus brasiliensis (0,17%) were much rarer. A single specimen of Cryptonanus sp. was identified among the diet items based on distinctive dental characters. The identification of this genus in the present study represents the second record in the state of Rio de Janeiro, and the sixth in the Atlantic Forest biome, suggesting that this marsupial occupies a wider ecological and biogeographic range. The present study underscores the relevance of owl pellets for small mammal surveys, even in urban and highly disturbed areas.

On the biochemical associations of FoxO3a and SirT1 with the stress resistance of cells from the slow senescing Snell dwarf Mouse

Tailskin fibroblasts from multiple genotypes of slow aging mice have been shown to be resistant to a broad spectrum of toxicants. The molecular determinants for this in vitro effect, as well as for the delayed/ decelerated senescence of these mice, are uncertain. Here, we have extended this phenomenon of in vitro cellular stress resistance to neurons derived from the cerebral cortex of the Snell Dwarf Mouse. We further investigated the role of the transcription factor FoxO3a and the protein deacetylase SirT1, proteins known to positively mediate cellular stress-resistance, in this paradigm. We found that Snell Dwarfs have a greater proportion of nuclear-localized FoxO3a within their cerebrums than their littermate controls and that the same is true for their unstressed fibroblasts in vitro; yet, Snell Dwarf fibroblasts did not differ in FoxO3a properties in response to the application of three different concentrations of two disparate stresses. Similar results were obtained for SirT1, although SirT1 content did increase under the mild cellular stress of serum deprivation. Taken together, these results depict stress resistance in non-fibroblast cell types of incontrovertible physiological import explanted from slow aging mice. Also, these results strongly suggest that neither FoxO3a nor SirT1 robustly regulate the stress-resistance of Snell Dwarf Mouse cells in vitro, and thus might not play a role in other slow aging mammalian in vitro models in which stress resistance has been documented. That cerebral neurons ex vivo and unstressed fibroblasts in vitro display FoxO3a concentrations suggestive of increased activity introduce the possibility that FoxO3a might partially mediate the in vivo retardation of senescence of these mice.

On the biochemical associations of FoxO3a and SirT1 with the stress resistance of cells from the slow senescing Snell dwarf Mouse

Tailskin fibroblasts from multiple genotypes of slow aging mice have been shown to be resistant to a broad spectrum of toxicants. The molecular determinants for this in vitro effect, as well as for the delayed/ decelerated senescence of these mice, are uncertain. Here, we have extended this phenomenon of in vitro cellular stress resistance to neurons derived from the cerebral cortex of the Snell Dwarf Mouse. We further investigated the role of the transcription factor FoxO3a and the protein deacetylase SirT1, proteins known to positively mediate cellular stress-resistance, in this paradigm. We found that Snell Dwarfs have a greater proportion of nuclear-localized FoxO3a within their cerebrums than their littermate controls and that the same is true for their unstressed fibroblasts in vitro; yet, Snell Dwarf fibroblasts did not differ in FoxO3a properties in response to the application of three different concentrations of two disparate stresses. Similar results were obtained for SirT1, although SirT1 content did increase under the mild cellular stress of serum deprivation. Taken together, these results depict stress resistance in non-fibroblast cell types of incontrovertible physiological import explanted from slow aging mice. Also, these results strongly suggest that neither FoxO3a nor SirT1 robustly regulate the stress-resistance of Snell Dwarf Mouse cells in vitro, and thus might not play a role in other slow aging mammalian in vitro models in which stress resistance has been documented. That cerebral neurons ex vivo and unstressed fibroblasts in vitro display FoxO3a concentrations suggestive of increased activity introduce the possibility that FoxO3a might partially mediate the in vivo retardation of senescence of these mice.