Isosaxalin

25987881

The Rhinella margaritifera species group consists of 17 species of toads distributed in tropical and subtropical South America and eastern Central America. The identity of some of its species is poorly understood and there are numerous undescribed cryptic species. Among them, the status of Rhinella margaritifera is one of the most problematic. Its range includes lowland rainforests separated by the Andes, the Chocoan rainforest to the west and the Amazonian rainforest to the east. This distribution is puzzling because the Andes are an old and formidable barrier to gene flow and therefore should generate vicariant speciation between disjunct lowland populations. Herein we clarify the taxonomy of populations of the Rhinella margaritifera complex from Central America and the Choco region of South America. The morphological and genetic variation of Rhinella margaritifera was examined from 39 populations from Choco, 24 from the upper Amazon region of Ecuador, and 37 from Panama, including the holotype of the Panamanian Rhinella alata. Phylogenetic analyses were performed based on mitochondrial genes 12S rRNA, 16S rRNA, and cytochrome c oxidase I (COI) and the nuclear gene Tyrosinase (Tyr). The genetic and morphological data show that Panamanian and Chocoan populations are conspecific. In the phylogeny, populations from Choco and Panama form a well-supported clade. The morphology of the holotype of Rhinella alata falls within the variation range of Panamanian and Chocoan populations. Based on all this evidence, we assign the populations from western Ecuador and Panama to Rhinella alata and demonstrate that the unusual distribution pattern of “Rhinella margaritifera” on both sides of the Andes was an artifact of incorrectly defined species boundaries.

Andes, Biogeography, Choco, Morphology, Panama, Phylogeny, Rhinella alata

Systematics of the Rhinella margaritifera complex ( Anura, Bufonidae) from western Ecuador and Panama with insights in the biogeography of Rhinella alata

Sueny P. dos Santos,1 Roberto IbaNez,2,3 and Santiago R. Ron1

2015;

30179155

Catching primal functional changes in early, ‘very far from disease onset’ (VFDO) stages of Huntington’s disease is likely to be the key to a successful therapy. Focusing on VFDO stages, we assessed neuronal microcircuits in premanifest Hdh150 knock-in mice. Employing in vivo two-photon Ca2+ imaging, we revealed an early pattern of circuit dysregulation in the visual cortex – one of the first regions affected in premanifest Huntington’s disease – characterized by an increase in activity, an enhanced synchronicity and hyperactive neurons. These findings are accompanied by aberrations in animal behavior. We furthermore show that the antidiabetic drug metformin diminishes aberrant Huntingtin protein load and fully restores both early network activity patterns and behavioral aberrations. This network-centered approach reveals a critical window of vulnerability far before clinical manifestation and establishes metformin as a promising candidate for a chronic therapy starting early in premanifest Huntington’s disease pathogenesis long before the onset of clinical symptoms.

Research organism: C. elegans, Mouse

Metformin reverses early cortical network dysfunction and behavior changes in Huntington’s disease

Isabelle Arnoux,#1,† Michael Willam,#2,† Nadine Griesche,#3,† Jennifer Krummeich,2 Hirofumi Watari,1 Nina Offermann,3 Stephanie Weber,3 Partha Narayan Dey,4 Changwei Chen,5 Olivia Monteiro,5 Sven Buettner,3 Katharina Meyer,3 Daniele Bano,3 Konstantin Radyushkin,6 Rosamund Langston,5,6 Jeremy J Lambert,5 Erich Wanker,7 Axel Methner,#4,‡ Sybille Krauss,#3,‡ Susann Schweiger,#2,‡ and Albrecht Stroh#1,‡

2018;