The Development of Endothermy during Pouch Life in the Eastern Barred Bandicoot (Perameles gunnii), a Marsupial

Viperidae snakes infected by mammalian-associated trypanosomatids and a free-living kinetoplastid

Trypanosomatids have achieved significant evolutionary success in parasitizing various groups, yet reptiles remain relatively unexplored. The utilization of advanced molecular tools has revealed an increased richness of trypanosomatids in vertebrate hosts. The aim of this study was to identify the trypanosomatid species infecting Bothrops moojeni and Crotalus durissus kept in captivity from 2000 to 2022. Blood samples were obtained from 106 snakes: 73C. durissus and 33 B. moojeni. Whole blood was collected for hemoculture, blood smears and centrifugated to obtain the blood clot that had its DNA extracted and submitted to Nested PCR (18S rDNA gene) to detect Trypanosomatidae. Positive samples were quantified and submitted to both conventional (Sanger) and next generation sequencing (NGS). Cloning of the amplified PCR product was performed for only one individual of C. durissus. To exclude the possibility of local vector transmission, attempts to capture sandflies were conducted using six CDC-LT type light traps. Molecular diagnosis revealed that 34% of the snakes presented trypanosomatid DNA, 47.94% in C. durissus and 3.9% in B. moojeni. The cloning process generated four colonies identified as a new MOTU named Trypanosomatidae sp. CROT. The presence of DNA of five trypanosomatids (Trypanosoma cruzi TcII/VI, Trypanosoma sp. DID, Trypanosoma cascavelli, Trypanosomatidae sp. CROT, Leishmania infantum and Leishmania sp.) and one free-living kinetoplastid (Neobodo sp.) was revealed through NGS and confirmed by phylogenetic analysis. The haplotypic network divided the T. cascavelli sequences into two groups, 1) marsupials and snakes and 2) exclusive to marsupials. Therefore, the diversity of Kinetoplastea is still underestimated. Snakes have the ability to maintain infection with T. cruzi and L. infantum for up to 20 years and the DNA finding of Neobodo sp. in the blood of a C. durissus suggests that this genus can infect vertebrates.

The hibernating South American marsupial, Dromiciops gliroides, displays torpor-sensitive microRNA expression patterns

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.

Marsupial uncoupling protein 1 sheds light on the evolution of mammalian nonshivering thermogenesis

Brown adipose tissue expressing uncoupling protein 1 (UCP1) is responsible for adaptive nonshivering thermogenesis giving eutherian mammals crucial advantage to survive the cold. The emergence of this thermogenic organ during mammalian evolution remained unknown as the identification of UCP1 in marsupials failed so far. Here, we unequivocally identify the marsupial UCP1 ortholog in a genomic library of Monodelphis domestica. In South American and Australian marsupials, UCP1 is exclusively expressed in distinct adipose tissue sites and appears to be recruited by cold exposure in the smallest species under investigation (Sminthopsis crassicaudata). Our data suggest that an archetypal brown adipose tissue was present at least 150 million yr ago allowing early mammals to produce endogenous heat in the cold, without dependence on shivering and locomotor activity.