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Gabriel M. Martin - One of the best experts on this subject based on the ideXlab platform.

  • The Palmar and Plantar Anatomy of Dromiciops gliroides Thomas, 1894 (Marsupialia, Microbiotheria) and its Relationship to Australian Marsupials
    Journal of Mammalian Evolution, 2019
    Co-Authors: Gabriel M. Martin
    Abstract:

    The monito del monte Dromiciops gliroides Thomas, 1894 , is a marsupial endemic to the temperate rainforests of Argentina and Chile. Studies on its phylogenetic relationships show the species is more closely related to Australian marsupials than to any other American taxon. The study of the palmar and plantar anatomy in this species through direct observation of more than 86 specimens and comparisons with American and Australian marsupials show the pattern of D. gliroides is derived from the ancestral mammalian pattern. Dromiciops gliroides show the presence of a single palmar/plantar pad in the position of interdigital pad 1 and the lack of a thenar pad (or the complete fusion between both pads), a pattern that appears closer to some Australian diprotodont marsupials. Also shared with several Australian marsupials is the transverse orientation of pad ridges, a condition that is not shared with most arboreal/scansorial American marsupials (e.g., Caluromys spp., Marmosa spp., Marmosops spp.).

  • Dental anomalies in Caluromys (Marsupialia, Didelphimorphia, Didelphidae, Caluromyinae) and a reassessment of malformations in New World marsupials (Didelphimorphia, Microbiotheria and Paucituberculata)
    Mammalia, 2018
    Co-Authors: Gabriel M. Martin, Maria Amelia Chemisquy
    Abstract:

    Abstract Dental anomalies have been documented in almost all mammalian orders, and include supernumerary or missing teeth, teeth with aberrant occlusal surfaces and/or roots and teeth in unusual positions. Our objectives were the description and categorization of dental anomalies in all species of the genus Caluromys. We studied 462 crania, recorded and classified dental anomalies in four categories: variations in occlusal/root morphology; teeth in unusual positions; supernumerary/missing teeth; presence of unshed deciduous premolars. We found anomalies in all species, with a percentage ranging from 11% to 6.3%. Caluromys derbianus produced anomalous M4/m4 and flipped crowns, the other two species produced higher numbers of missing teeth. We infer that flipped crowns might have consequences in mastication, while other anomalies seem to be less functionally important, especially those at the end of the toothrow. Comparisons with other New World marsupials show caluromyines have more anomalies in M4/m4 shape (similar to microbiotherids) and flipped crowns, while didelphids have more supernumerary teeth, and caenolestids have more missing teeth.

  • Variability and variation in Dromiciops Thomas, 1894 (Marsupialia, Microbiotheria, Microbiotheriidae)
    Journal of Mammalogy, 2017
    Co-Authors: Gabriel M. Martin
    Abstract:

    The genus Dromiciops Thomas is the only living representative of the order Microbiotheria. Throughout the history of the taxon, it was considered to comprise a continental and an insular form (D. australis and D. gliroides), a single species (D. gliroides), or, as recently described, 3 different species (D. bozinovici, D. mondaca, and D. gliroides). I analyzed the morphometric and morphologic variability (differences in morphological characters within a sample or species) and variation (differences in morphological characters among samples or species) in Dromiciops. Comparisons to test for secondary sexual dimorphism were made within and between continental and insular samples for localities with the largest samples available. Due to the lack of sexual dimorphism, males and females were analyzed together to test for: 1) differences between continental and insular samples; 2) differences between the arrangement of recently described species using a larger series of available specimens; and 3) clinal variation. Results support Dromiciops as composed of 1 valid species (D. gliroides), without clinal variation. Based on the samples I examined, several characters previously used as diagnostic for the 3 species previously recognized (e.g., incisive and palatal fenestrae, mandibular height) vary intraspecifically and are not valid as diagnostic.

  • Paleobiology and Adaptations of Paleogene Metatherians
    A Brief History of South American Metatherians, 2015
    Co-Authors: Francisco J. Goin, Gabriel M. Martin, Ana Natalia Zimicz, Michael O. Woodburne, Laura Chornogubsky
    Abstract:

    Diversity, dietary, and body mass analyses suggest that the early Eocene represents the major radiation event in South America metatherian evolutionary history. During this period, representatives of all orders typical of the Paleogene reached their greatest diversity (i.e., “basal ameridelphians”; Polydolopimorphia Polydolopiformes, and Bonapartheriiformes Bonapartherioidea); frugivory was the dominant trophic niche. By the middle late Eocene occurs a functional and taxonomic turnover. Among the Polydolopimorphia, frugivore types declined and were replaced by larger-sized frugivores/folivores (Polydolopiformes) and smaller-sized granivores (Bonapartheriiformes). The Sparassodonta showed a diversity increase and occupied the large-sized hypercarnivore niches. The Eocene–Oligocene boundary constitutes another extinction and turnover event marked by the disappearance of “basal ameridelphians”, the Polydolopiformes and Bonapartheriiformes Bonapartherioidea. Lineages that survive into the Deseadan are the Sparassodonta, Paucituberculata, Microbiotheria, and Bonapartheriiformes Argyrolagoidea. Dominant trophic types were those of carnivores and granivores. Environmental factors probably modeled the Paleogene metatherian faunal dynamics in South America. Mean annual temperatures (MAT) and precipitations seem the main factors modeling the taxonomic and trophic diversity, respectively. The adaptive radiation of the early Eocene seems associated with the maximum thermal event of the late Paleocene-early Eocene. The turnover event of the late Eocene seems associated with a sharp drop in the rainfall regime. The extinction and turnover event of the Eocene–Oligocene boundary also seem associated with a strong drop in ambient temperatures. The diversity in evolution of Paleogene metatherians shows a pattern similar to that of living marsupials at the latitudinal level. For a given mean temperature, the number of species in extinct associations is very close to that of the living ones.

  • Phylogeny and Diversity of South American Metatherians
    A Brief History of South American Metatherians, 2015
    Co-Authors: Francisco J. Goin, Gabriel M. Martin, Ana Natalia Zimicz, Michael O. Woodburne, Laura Chornogubsky
    Abstract:

    The Metatheria include not only marsupials but all therians more related to Marsupialia than to the Eutheria. Marsupialia is considered as a metatherian crown group including all extant marsupials, their common ancestor and all of their descendants. “Ameridelphia” is not a natural group. Australidelphia includes the Microbiotheria and all Australasian marsupials. Several authors also argue that the Polydolopimorphia are Australidelphians as well. Relationships of Sparassodonta with other Metatheria are a matter of discussion. To several authors, they are more closely related to South American and Australian groups than to basal North American and/or Asian metatherians. Our concept of Didelphimorphia includes the Peradectoidea (Peradectidae and Caroloameghiniidae) and the Didelphoidea (Didelphidae and Sparassocynidae). In several analyses, the Paucituberculata appear as more closely related to the Australidelphia than to the Didelphimorphia. The relationships of the Microbiotheria within the Australidelphia have been subject of much discussion. They have been considered either as sister-taxa of all other Australidelphia, at the base of Diprotodontia, as a sister-taxon of Dasyuromorpha, as a sister-taxon of Phalangeriformes + Diprotodontia, or even related with part of the former.

Roberto F. Nespolo - One of the best experts on this subject based on the ideXlab platform.

  • The Biogeography of Dromiciops in Southern South America: middle Miocene transgressions, speciation and associations with Nothofagus
    2020
    Co-Authors: J. F. Quintero-galvis, Pablo Saenz-agudelo, G. Amico, S. Vazquez, J. Celis-diez, Aaron B. A. Shafer, Roberto F. Nespolo
    Abstract:

    AimSeveral geological events affecting Southern South America during the middle Miocene climatic optimum acted as important drivers of diversification to the biota. This is the case of Microbiotheria, for which Dromiciops is considered the sole surviving lineage, the sister group of Eomarsupialia (Australian marsupials). Three main Dromiciops genetic lineages are known, whose divergence was initially attributed to recent Pleistocene glaciations. Using fossil-calibrated dating on nuclear and mitochondrial genes, here we reevaluate this hypothesis and report an older (Miocenic) biogeographic history for the genus. LocationSouthern South America. MethodsPhylogenetic reconstruction using sequences from two mitochondrial DNA and four nuclear DNA genes in 159 specimens, from 31 sites across Chile and Argentina. Divergence time estimation using fossil calibration. ResultsOur phylogenetic analysis resolved four well supported clades with discrete geographic distributions. The oldest and most differentiated clade corresponds to that of the northern distribution (35.2{degrees}S to 39.3{degrees}S), which would be a different species (D. bozinovici, sensu Delia et al. 2016). According to our estimations, this species shared a common ancestor with D. gliroides (southern clades) about 13 million years ago (95% CI: 6.4-25.3). The southern clades (39.6{degrees}S to 42.0{degrees}S), showed a divergence time ranging from 9.57 to 6.5 Mya. Strong genetic structure was detected from north to south but not across the Andes, or between Chiloe island/ mainland. Demographic equilibrium is inferred to the northern clade, and recent demographic expansions was detected in the central and southern clades. Main conclusionsThe whole diversification of Dromiciops occurred within the Miocene, being the Middle Miocene transgression (MMT), the massive marine flooding that covered several lowlands of the western face of los Andes between 38-48{degrees} S, the most likely diversifying force. This was the result of an increase in global sea levels due to the Miocene climatic optimum, which shaped the biogeographic origin of several species, including Nothofagus forests, the habitat main of Dromiciops.

  • Strategies of biochemical adaptation for hibernation in a South American marsupial Dromiciops gliroides: 1. Mitogen-activated protein kinases and the cell stress response.
    Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology, 2018
    Co-Authors: Sanoji Wijenayake, Roberto F. Nespolo, Bryan E. Luu, Jing Zhang, Shannon N. Tessier, Julian F. Quintero-galvis, Juan Diego Gaitán-espitia, Kenneth B. Storey
    Abstract:

    Hibernation is a period of torpor and heterothermy that is typically associated with a strong reduction in metabolic rate, global suppression of transcription and translation, and upregulation of various genes/proteins that are central to the cellular stress response such as protein kinases, antioxidants, and heat shock proteins. The current study examined cell signaling cascades in hibernating monito del monte, Dromiciops gliroides, a South American marsupial of the Order Microbiotheria. Responses to hibernation by members of the mitogen-activated protein kinase (MAPK) pathways, and their roles in coordinating hibernator metabolism were examined in liver, kidney, heart and brain of control and versus hibernating (4days continuous torpor) D. gliroides. The targets evaluated included key protein kinases in their activated phosphorylated forms (p-ERK/MAPK 1/2, p-MEK1, p-MSK1, p-p38, p-JNK) and related target proteins (p-CREB 2, p-ATF2, p-c-Jun and p-p53). Liver exhibited a strong coordinated response by MAPK members to hibernation with significant increases in protein phosphorylation levels of p-MEK1, p-ERK/MAPK1/2, p-MSK1, p-JNK and target proteins c-Jun, and p-ATF2, all combining to signify a strong activation of MAPK signaling during hibernation. Kidney also showed activation of MAPK cascades with significant increases in p-MEK1, p-ERK/MAPK1/2, p-p38, and p-c-Jun levels in hibernating animals. By contrast, responses by heart and brain indicated reduced MAPK pathway function during torpor with reduced phosphorylation of targets including p-ERK/MAPK 1/2 in both tissues as well as lower p-p38 and p-JNK content in heart. Overall, the data indicate a vital role for MAPK signaling in regulating the cell stress response during marsupial hibernation.

  • the hibernating south american marsupial dromiciops gliroides displays torpor sensitive microrna expression patterns
    Scientific Reports, 2016
    Co-Authors: Hanane Hadjmoussa, Roberto F. Nespolo, Jaso Moggridge, Ya E Luu, Julia F Quinterogalvis, Juan Diego Gaitanespitia, Kenneth Storey
    Abstract:

    When faced with adverse environmental conditions, the marsupial Dromiciops gliroides uses either daily or seasonal torpor to support survival and is the only known hibernating mammal in South America. As the sole living representative of the ancient Order Microbiotheria, this species can provide crucial information about the evolutionary origins and biochemical mechanisms of hibernation. Hibernation is a complex energy-saving strategy that involves changes in gene expression that are elicited in part by microRNAs. To better elucidate the role of microRNAs in orchestrating hypometabolism, a modified stem-loop technique and quantitative PCR were used to characterize the relative expression levels of 85 microRNAs in liver and skeletal muscle of control and torpid D. gliroides. Thirty-nine microRNAs were differentially regulated during torpor; of these, 35 were downregulated in liver and 11 were differentially expressed in skeletal muscle. Bioinformatic analysis predicted that the downregulated liver microRNAs were associated with activation of MAPK, PI3K-Akt and mTOR pathways, suggesting their importance in facilitating marsupial torpor. In skeletal muscle, hibernation-responsive microRNAs were predicted to regulate focal adhesion, ErbB, and mTOR pathways, indicating a promotion of muscle maintenance mechanisms. These tissue-specific responses suggest that microRNAs regulate key molecular pathways that facilitate hibernation, thermoregulation, and prevention of muscle disuse atrophy.

  • aerobic power huddling and the efficiency of torpor in the south american marsupial dromiciops gliroides
    Biology Open, 2012
    Co-Authors: Marcela Franco, Pablo Cortés, Carolina Contreras, Mark A Chappell, Mauricio Sotogamboa, Roberto F. Nespolo
    Abstract:

    During periods of cold, small endotherms depend on a continuous supply of food and energy to maintain euthermic body temperature (T(b)), which can be challenging if food is limited. In these conditions, energy-saving strategies are critical to reduce the energetic requirements for survival. Mammals from temperate regions show a wide arrange of such strategies, including torpor and huddling. Here we provide a quantitative description of thermoregulatory capacities and energy-saving strategies in Dromiciops gliroides, a Microbiotherid marsupial inhabiting temperate rain forests. Unlike many mammals from temperate regions, preliminary studies have suggested that this species has low capacity for control and regulation of body temperature, but there is still an incomplete picture of its bioenergetics. In order to more fully understand the physiological capacities of this "living fossil", we measured its scope of aerobic power and the interaction between huddling and torpor. Specifically, we evaluated: (1) the relation between basal (BMR) and maximum metabolic rate (MMR), and (2) the role of huddling on the characteristics of torpor at different temperatures. We found that BMR and MMR were above the expected values for marsupials and the factorial aerobic scope (from [Formula: see text]CO(2)) was 6.0±0.45 (using [Formula: see text]CO(2)) and 6.2±0.23 (using [Formula: see text]O(2)), an unusually low value for mammals. Also, repeatability of physiological variables was non-significant, as in previous studies, suggesting poor time-consistency of energy metabolism. Comparisons of energy expenditure and body temperature (using attached data-loggers) between grouped and isolated individuals showed that at 20°C both average resting metabolic rate and body temperature were higher in groups, essentially because animals remained non-torpid. At 10°C, however, all individuals became torpid and no differences were observed between grouped and isolated individuals. In summary, our study suggests that the main response of Dromiciops gliroides to low ambient temperature is reduced body temperature and torpor, irrespective of huddling. Low aerobic power and low time-consistency of most thermoregulatory traits of Dromiciops gliroides support the idea of poor thermoregulatory abilities in this species.

  • Bioenergetics and intestinal phenotypic flexibility in the microbiotherid marsupial (Dromiciops gliroides) from the temperate forest in South America.
    Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2011
    Co-Authors: Pablo Cortés, Marcela Franco, Pablo Sabat, Silvia A. Quijano, Roberto F. Nespolo
    Abstract:

    Abstract The microbiotherid marsupial Dromiciops gliroides inhabits the temperate forests of the Southern hemisphere, facing seasonal nutritional and energetic bottlenecks due to its apparently facultative insectivory/frugivory. In order to understand the physiological processes behind this ecological pattern, we studied the morpho-physiological changes that D. gliroides exhibits after dietary acclimation, in a sample of 21 wild-caught individuals fed over 1 month with ad libitum diet of: (1) fruit, (2) insects or (3) a mix of insects and fruit. In addition, we measured oxygen consumption (VO 2 ) at resting conditions. We also performed enzyme assays (sucrase, maltase, trehalase and aminopeptidase N) and measurements of organ morphology. We found that D. gliroides cannot fulfil its nutrient requirements only from insects or fruit. It needs a mixed diet in order to maintain its body mass and energy balance. However, as a response of diet acclimation, individuals showed several-fold changes in the activities of aminopeptidase-N, maltase and sucrase (but not trehalase). This result, both the magnitude of change and the simultaneous effects on three enzymes suggests that D. gliroides could exhibit adaptive phenotypic plasticity in the activity of intestinal enzymes. This study suggests also that D. gliroides , the only living representative of the Microbiotheria order, exhibits physiological adaptations to a generalist diet.

Robin M. D. Beck - One of the best experts on this subject based on the ideXlab platform.

  • The Skull of Epidolops ameghinoi from the Early Eocene Itaboraí Fauna, Southeastern Brazil, and the Affinities of the Extinct Marsupialiform Order Polydolopimorphia
    Journal of Mammalian Evolution, 2017
    Co-Authors: Robin M. D. Beck
    Abstract:

    The skull of the polydolopimorphian marsupialiform Epidolops ameghinoi is described in detail for the first time, based on a single well-preserved cranium and associated left and right dentaries plus additional craniodental fragments, all from the early Eocene (53–50 million year old) Itaboraí fauna in southeastern Brazil. Notable craniodental features of E. ameghinoi include absence of a masseteric process, very small maxillopalatine fenestrae, a prominent pterygoid fossa enclosed laterally by a prominent ectopterygoid crest, an absent or tiny transverse canal foramen, a simple, planar glenoid fossa, and a postglenoid foramen that is immediately posterior to the postglenoid process. Most strikingly, the floor of the hypotympanic sinus was apparently unossified, a feature found in several stem marsupials but absent in all known crown marsupials. “Type II” marsupialiform petrosals previously described from Itaboraí plausibly belong to E. ameghinoi ; in published phylogenetic analyses, these petrosals fell outside (crown-clade) Marsupialia. “IMG VII” tarsals previously referred to E. ameghinoi do not share obvious synapomorphies with any crown marsupial clade, nor do they resemble those of the only other putative polydolopimorphians represented by tarsal remains, namely the argyrolagids. Most studies have placed Polydolopimorphia within Marsupialia, related to either Paucituberculata, or to Microbiotheria and Diprotodontia. However, diprotodonty almost certainly evolved independently in polydolopimorphians, paucituberculatans and diprotodontians, and Epidolops does not share obvious synapomorphies with any marsupial order. Epidolops is dentally specialized, but several morphological features appear to be more plesiomorphic than any crown marsupial. It seems likely Epidolops that falls outside Marsupialia, as do morphologically similar forms such as Bonapartherium and polydolopids. Argyrolagids differ markedly in their known morphology from Epidolops but share some potential apomorphies with paucituberculatans. It is proposed that Polydolopimorphia as currently recognised is polyphyletic, and that argyrolagids (and possibly other taxa currently included in Argyrolagoidea, such as groeberiids and patagoniids) are members of Paucituberculata. This hypothesis is supported by Bayesian non-clock phylogenetic analyses of a total evidence matrix comprising DNA sequence data from five nuclear protein-coding genes, indels, retroposon insertions, and morphological characters: Epidolops falls outside Marsupialia, whereas argyrolagids form a clade with the paucituberculatans Caenolestes and Palaeothentes , regardless of whether the Type II petrosals and IMG VII tarsals are used to score characters for Epidolops or not. There is no clear evidence for the presence of crown marsupials at Itaboraí, and it is possible that the origin and early evolution of Marsupialia was restricted to the “Austral Kingdom” (southern South America, Antarctica, and Australia).

  • The Skull of Epidolops ameghinoi from the Early Eocene Itaboraí Fauna, Southeastern Brazil, and the Affinities of the Extinct Marsupialiform Order Polydolopimorphia
    Journal of Mammalian Evolution, 2017
    Co-Authors: Robin M. D. Beck
    Abstract:

    The skull of the polydolopimorphian marsupialiform Epidolops ameghinoi is described in detail for the first time, based on a single well-preserved cranium and associated left and right dentaries plus additional craniodental fragments, all from the early Eocene (53–50 million year old) Itaboraí fauna in southeastern Brazil. Notable craniodental features of E. ameghinoi include absence of a masseteric process, very small maxillopalatine fenestrae, a prominent pterygoid fossa enclosed laterally by a prominent ectopterygoid crest, an absent or tiny transverse canal foramen, a simple, planar glenoid fossa, and a postglenoid foramen that is immediately posterior to the postglenoid process. Most strikingly, the floor of the hypotympanic sinus was apparently unossified, a feature found in several stem marsupials but absent in all known crown marsupials. “Type II” marsupialiform petrosals previously described from Itaboraí plausibly belong to E. ameghinoi ; in published phylogenetic analyses, these petrosals fell outside (crown-clade) Marsupialia. “IMG VII” tarsals previously referred to E. ameghinoi do not share obvious synapomorphies with any crown marsupial clade, nor do they resemble those of the only other putative polydolopimorphians represented by tarsal remains, namely the argyrolagids. Most studies have placed Polydolopimorphia within Marsupialia, related to either Paucituberculata, or to Microbiotheria and Diprotodontia. However, diprotodonty almost certainly evolved independently in polydolopimorphians, paucituberculatans and diprotodontians, and Epidolops does not share obvious synapomorphies with any marsupial order. Epidolops is dentally specialized, but several morphological features appear to be more plesiomorphic than any crown marsupial. It seems likely Epidolops that falls outside Marsupialia, as do morphologically similar forms such as Bonapartherium and polydolopids. Argyrolagids differ markedly in their known morphology from Epidolops but share some potential apomorphies with paucituberculatans. It is proposed that Polydolopimorphia as currently recognised is polyphyletic, and that argyrolagids (and possibly other taxa currently included in Argyrolagoidea, such as groeberiids and patagoniids) are members of Paucituberculata. This hypothesis is supported by Bayesian non-clock phylogenetic analyses of a total evidence matrix comprising DNA sequence data from five nuclear protein-coding genes, indels, retroposon insertions, and morphological characters: Epidolops falls outside Marsupialia, whereas argyrolagids form a clade with the paucituberculatans Caenolestes and Palaeothentes , regardless of whether the Type II petrosals and IMG VII tarsals are used to score characters for Epidolops or not. There is no clear evidence for the presence of crown marsupials at Itaboraí, and it is possible that the origin and early evolution of Marsupialia was restricted to the “Austral Kingdom” (southern South America, Antarctica, and Australia).

  • An ‘ameridelphian’ marsupial from the early Eocene of Australia supports a complex model of Southern Hemisphere marsupial biogeography
    Naturwissenschaften, 2012
    Co-Authors: Robin M. D. Beck
    Abstract:

    Recent molecular data strongly support the monophyly of all extant Australian and New Guinean marsupials (Eomarsupialia) to the exclusion of extant South American marsupials. This, together with available geological and fossil evidence, has been used to argue that the presence of marsupials in Australia is simply the result of a single dispersal event from South America during the latest Cretaceous or Palaeocene, without subsequent dispersals between the two continents. Here, I describe an isolated ankle bone (calcaneus) of a metatherian from the early Eocene Tingamarra Local Fauna in northeastern Australia. Strikingly, this specimen, QM F30060, lacks the ‘continuous lower ankle joint pattern’ (CLAJP), presence of which is a highly distinctive apomorphy of the marsupial clade Australidelphia, which includes Eomarsupialia, the living South American Microbiotherian Dromiciops and the Tingamarran fossil marsupial Djarthia . Comparisons with a range of marsupials and stem-metatherians strongly suggest that the absence of the CLAJP in QM F30060 is plesiomorphic, and that this specimen represents the first unequivocal non-australidelphian (‘ameridelphian’) metatherian known from Australia. This interpretation is confirmed by phylogenetic analyses that place QM F30060 within (crown-group) Marsupialia, but outside Australidelphia. Based on these results, the distribution of marsupials within Gondwana cannot be explained by simply a single dispersal event from South America and Australia. Either there were multiple dispersals by marsupials (and possibly also stem-metatherians) between South America and Australia, in one or both directions, or, alternatively, there was a broadly similar metatherian fauna stretching across southern South America, Antarctica and Australia during the Late Cretaceous–early Palaeogene.

Kenneth Storey - One of the best experts on this subject based on the ideXlab platform.

  • the hibernating south american marsupial dromiciops gliroides displays torpor sensitive microrna expression patterns
    Scientific Reports, 2016
    Co-Authors: Hanane Hadjmoussa, Roberto F. Nespolo, Jaso Moggridge, Ya E Luu, Julia F Quinterogalvis, Juan Diego Gaitanespitia, Kenneth Storey
    Abstract:

    When faced with adverse environmental conditions, the marsupial Dromiciops gliroides uses either daily or seasonal torpor to support survival and is the only known hibernating mammal in South America. As the sole living representative of the ancient Order Microbiotheria, this species can provide crucial information about the evolutionary origins and biochemical mechanisms of hibernation. Hibernation is a complex energy-saving strategy that involves changes in gene expression that are elicited in part by microRNAs. To better elucidate the role of microRNAs in orchestrating hypometabolism, a modified stem-loop technique and quantitative PCR were used to characterize the relative expression levels of 85 microRNAs in liver and skeletal muscle of control and torpid D. gliroides. Thirty-nine microRNAs were differentially regulated during torpor; of these, 35 were downregulated in liver and 11 were differentially expressed in skeletal muscle. Bioinformatic analysis predicted that the downregulated liver microRNAs were associated with activation of MAPK, PI3K-Akt and mTOR pathways, suggesting their importance in facilitating marsupial torpor. In skeletal muscle, hibernation-responsive microRNAs were predicted to regulate focal adhesion, ErbB, and mTOR pathways, indicating a promotion of muscle maintenance mechanisms. These tissue-specific responses suggest that microRNAs regulate key molecular pathways that facilitate hibernation, thermoregulation, and prevention of muscle disuse atrophy.

Fontúrbel, Francisco E. - One of the best experts on this subject based on the ideXlab platform.

  • PATRONES DE USO, SELECCION DE HABITAT Y RESPUESTAS A LA FRAGMENTACION DEL MONITO DEL MONTE (DROMICIOPS GLIROIDES THOMAS) EN UN PAISAJE DEL SUR DE CHILE
    2013
    Co-Authors: Fontúrbel, Francisco E.
    Abstract:

    El monito del monte (Dromiciops gliroides Thomas 1894) es un marsupial arborícola, endémico de los bosques lluviosos templados de Sudamérica, donde desempeñaría un importante rol ecológico como dispersor de semillas. Es considerado como especie prioritaria para la conservación por ser el único representante viviente del orden Microbiotheria, un linaje Gondwánico cercanamente relacionado con los marsupiales australianos. Actualmente está considerado como especie amenazada, figurando como "Rara" en la legislación chilena, y como Vulnerable A1c según la UICN, debido a las bajas abundancias reportadas y a la rápida pérdida y fragmentación de su hábitat. En esta investigación, desarrollada en la localidad de Cascadas entre marzo y mayo de 2008, se determinó que las bajas abundancias anteriormente reportadas se deben a un artefacto de muestreo. Los métodos tradicionales para la captura de pequeños mamíferos no funcionan bien para capturar a D. gliroides, mientras que los métodos más eficientes para capturar a esta especie no tienen un buen desempeño para la captura de roedores, siendo mutualmente excluyentes. Mediante métodos de muestreo mejorados, se estimaron densidades poblacionales de hasta 43 individuos/ha, sugiriendo que ésta no es una especie numéricamente escasa. A partir de datos de telemetría de cinco individuos, se estimaron los tamaños de ámbito de hogar de D. gliroides en 2.34±1.89 ha (media±1 DE), con movimientos lineales de 100-200m. Los ámbitos de hogar bidimensionales de los animales rastreados mostraron un alto nivel de solapamiento (50%) entre vecinos, mientras que a nivel de las áreas núcleo éste fue menor (23%), sugiriendo que cada individuo posee su propio espacio, pero que comparte un área mayor, y los recursos de ésta, con otros individuos. Usando intervalos de confianza de Bonferroni y un análisis composicional, se determinó que esta especie prefiere los ambientes de bosque maduro, seguido de los ambientes de renoval, y no ingresa a los ambientes de pradera. También se determinó que claramente evitan los ambientes de matorral. Los resultados obtenidos sugieren que D. gliroides sería una especie tolerante a la perturbación, pudiendo vivir en renovales boscosos que mantengan una cierta estructura y complejidad espacial. Adicionalmente, también parece ser una especie dependiente de la textura del hábitat, puesto que necesita de un cierto grado de densidad y complejidad en la estructura del bosque, la que parece ofrecerle refugio, alimento, conectividad, maniobrabilidad y protección contra los depredadores. Por ende, se esperaría la existencia de un umbral de perturbación, debajo el cual D. gliroides fuera capaz de persistir en ambientes perturbados, pero se vería negativamente afectado cuando las perturbaciones humanas reducen críticamente o eliminan elementos ambientales clave de los cuales depende

  • Ecological consistency across space: A synthesis of the ecological aspects of Dromiciops gliroides in Argentina and Chile
    'Springer Science and Business Media LLC', 2012
    Co-Authors: Fontúrbel, Francisco E., Franco Marcela, Rodríguez-cabal, Mariano A., Rivarola M. Daniela, Amico, Guillermo C.
    Abstract:

    Dromiciops gliroides is an arboreal marsupial found in the temperate forests of South America (36- 43 °S). This species is the sole extant representative of the order Microbiotheria, and is a key seed disperser of many native plant species, including the keystone mistletoe Tristerix corymbosus. Here, we synthesized the current knowledge on the ecological aspects of this species, and compared the available information from Argentina and Chile. Population density (23±2 (mean ± SE) individual/ha) and home range (1.6±0.6 ha) appear to be relatively similar across a marked ecological gradient in the mainland, but lower densities (7±2 individual/ha) and smaller home ranges (0.26±0.04 ha) were detected at island sites.We detected regional variation in body condition in Chile, but there were no significant differences across a wider E-W gradient. Movement patterns fit a random walk model; such behavior might have important consequences in shaping plant's spatial patterns. Although our data su

  • PATRONES DE USO, SELECCION DE HABITAT Y RESPUESTAS A LA FRAGMENTACION DEL MONITO DEL MONTE (DROMICIOPS GLIROIDES THOMAS) EN UN PAISAJE DEL SUR DE CHILE
    2008
    Co-Authors: Fontúrbel, Francisco E.
    Abstract:

    El monito del monte (Dromiciops gliroides Thomas 1894) es un marsupial arborícola, endémico de los bosques lluviosos templados de Sudamérica, donde desempeñaría un importante rol ecológico como dispersor de semillas. Es considerado como especie prioritaria para la conservación por ser el único representante viviente del orden Microbiotheria, un linaje Gondwánico cercanamente relacionado con los marsupiales australianos. Actualmente está considerado como especie amenazada, figurando como "Rara" en la legislación chilena, y como Vulnerable A1c según la UICN, debido a las bajas abundancias reportadas y a la rápida pérdida y fragmentación de su hábitat. En esta investigación, desarrollada en la localidad de Cascadas entre marzo y mayo de 2008, se determinó que las bajas abundancias anteriormente reportadas se deben a un artefacto de muestreo. Los métodos tradicionales para la captura de pequeños mamíferos no funcionan bien para capturar a D. gliroides, mientras que los métodos más eficientes para capturar a esta especie no tienen un buen desempeño para la captura de roedores, siendo mutualmente excluyentes. Mediante métodos de muestreo mejorados, se estimaron densidades poblacionales de hasta 43 individuos/ha, sugiriendo que ésta no es una especie numéricamente escasa. A partir de datos de telemetría de cinco individuos, se estimaron los tamaños de ámbito de hogar de D. gliroides en 2.34±1.89 ha (media±1DE), con movimientos lineales de 100-200m. Los ámbitos de hogar bidimensionales de los animales rastreados mostraron un alto nivel de solapamiento (50%) entre vecinos, mientras que a nivel de las áreas núcleo éste fue menor (23%), sugiriendo que cada individuo posee su propio espacio, pero que comparte un área mayor, y los recursos de ésta, con otros individuos. Usando intervalos de confianza de Bonferroni y un análisis composicional, se determinó que esta especie prefiere los ambientes de bosque maduro, seguido de los ambientes de renoval, y no ingresa a los ambientes de pradera. También se determinó que claramente evitan los ambientes de matorral. Los resultados obtenidos sugieren que D. gliroides sería una especie tolerante a la perturbación, pudiendo vivir en renovales boscosos que mantengan una cierta estructura y complejidad espacial. Adicionalmente, también parece ser una especie dependiente de la textura del hábitat, puesto que necesita de un cierto grado de densidad y complejidad en la estructura del bosque, la que parece ofrecerle refugio, alimento, conectividad, maniobrabilidad y protección contra los depredadores. Por ende, se esperaría la existencia de un umbral de perturbación, debajo el cual D. gliroides fuera capaz de persistir en ambientes perturbados, pero se vería negativamente afectado cuando las perturbaciones humanas reducen críticamente o eliminan elementos ambientales clave de los cuales depende.El monito del monte (Dromiciops gliroides Thomas 1894) es un marsupial arborícola, endémico de los bosques lluviosos templados de Sudamérica, donde desempeñaría un importante rol ecológico como dispersor de semillas. Es considerado como especie prioritar