POLG2 deficiency causes adult-onset syndromic sensory neuropathy, ataxia and parkinsonism

Objective: Mitochondrial dysfunction plays a key role in the pathophysiology of neurodegenerative disorders such as ataxia and Parkinson's disease. We describe an extended Belgian pedigree where seven individuals presented with adult-onset cerebellar ataxia, axonal peripheral ataxic neuropathy, and tremor, in variable combination with parkinsonism, seizures, cognitive decline, and ophthalmoplegia. We sought to identify the underlying molecular etiology and characterize the mitochondrial pathophysiology of this neurological syndrome. Methods: Clinical, neurophysiological, and neuroradiological evaluations were conducted. Patient muscle and cultured fibroblasts underwent extensive analyses to assess mitochondrial function. Genetic studies including genome-wide sequencing were conducted. Results: Hallmarks of mitochondrial dysfunction were present in patients' tissues including ultrastructural anomalies of mitochondria, mosaic cytochrome c oxidase deficiency, and multiple mtDNA deletions. We identified a splice acceptor variant in POLG2, c.970-1G>C, segregating with disease in this family and associated with a concomitant decrease in levels of POLG2 protein in patient cells. Interpretation: This work extends the clinical spectrum of POLG2 deficiency to include an overwhelming, adult-onset neurological syndrome that includes cerebellar syndrome, peripheral neuropathy, tremor, and parkinsonism. We therefore suggest to include POLG2 sequencing in the evaluation of ataxia and sensory neuropathy in adults, especially when it is accompanied by tremor or parkinsonism with white matter disease. The demonstration that deletions of mtDNA resulting from autosomal-dominant POLG2 variant lead to a monogenic neurodegenerative multicomponent syndrome provides further evidence for a major role of mitochondrial dysfunction in the pathomechanism of nonsyndromic forms of the component neurodegenerative disorders

The granite and glacial landscapes of the Peneda-Gerês National Park

Granite and glacial landforms are presented as the main geomorphological landscape features of the Peneda-Gerês National Park. The park was established in 1971 and it is the only national park and most important protected area in Portugal. The aesthetic attractiveness is supported mainly by the distinct granite landscape of the Gerês and Peneda Mountains, where the post-orogenic Variscan Gerês gran- ite facies occurs. The rugged relief is poorly covered by vegetation, differentiating it from the surrounding moun- tainous areas and the most distinctive landforms are bornhardts, locally named as “medas”. Typical glacial landforms, such as U-shaped valleys, cirques and moraines, express the sheltered character of a low-altitude glaciation, which is of great significance in the context of the Pleistocene glaciation in Southern Europe.This work is co-funded by the European Union through the European Regional Development Fund, based on COMPETE 2020 (Programa Operacional da Competitividade e Inter nacionalização), project ICT (UID/GEO/04683/2013) with reference POCI-01-0145- FEDER-007690 and Portuguese national funds pro vided by Fundação para a Ciência e Tecnologi

A dated phylogeny and collection records reveal repeated biome shifts in the African genus Coccinia (Cucurbitaceae)

Background: Conservatism in climatic tolerance may limit geographic range expansion and should enhance the effects of habitat fragmentation on population subdivision. Here we study the effects of historical climate change, and the associated habitat fragmentation, on diversification in the mostly sub-Saharan cucurbit genus Coccinia, which has 27 species in a broad range of biota from semi-arid habitats to mist forests. Species limits were inferred from morphology, and nuclear and plastid DNA sequence data, using multiple individuals for the widespread species. Climatic tolerances were assessed from the occurrences of 1189 geo-referenced collections and WorldClim variables. Results: Nuclear and plastid gene trees included 35 or 65 accessions, representing up to 25 species. The data revealed four species groups, one in southern Africa, one in Central and West African rain forest, one widespread but absent from Central and West African rain forest, and one that occurs from East Africa to southern Africa. A few individuals are differently placed in the plastid and nuclear (LFY) trees or contain two ITS sequence types, indicating hybridization. A molecular clock suggests that the diversification of Coccinia began about 6.9 Ma ago, with most of the extant species diversity dating to the Pliocene. Ancestral biome reconstruction reveals six switches between semi-arid habitats, woodland, and forest, and members of several species pairs differ significantly in their tolerance of different precipitation regimes. Conclusions: The most surprising findings of this study are the frequent biome shifts (in a relatively small clade) over just 6 - 7 million years and the limited diversification during and since the Pleistocene. Pleistocene climate oscillations may have been too rapid or too shallow for full reproductive barriers to develop among fragmented populations of Coccinia, which would explain the apparently still ongoing hybridization between certain species. Steeper ecological gradients in East Africa and South Africa appear to have resulted in more advanced allopatric speciation there

Les pointes de la Basse-Vallée du Tilemsi

Amblard-Rambert A., Gaussen J., Gaussen M. Les pointes de la Basse-Vallée du Tilemsi. In: Journal de la Société des Africanistes, 1960, tome 30, fascicule 2. pp. 123-143

SAHARAN DUST ON FUERTEVENTURA ISLAND (CANARIES): CHEMICAL AND MINERALOGICAL CHARACTERISTICS, AIR MASS TRAJECTORIES, AND PROBABLE SOURCES

International audienceFrom April 12 to 19, 1984, dust was [Windom, 1975; Chester et al., 1979; Sarnthein et collected by cascade impactor on Fuerteventura al., 1982] and, probably, to the mineral feeding Island, 100 km from the Saharan coast. The sam-of marine plankton. The dust outbreaks from ples were analyzed by X ray fluorescence spectro-northwestern Africa to the middle Atlantic and metry (elemental composition), by X ray diffrac-Western Europe have been much less studied. The tion (mineral constituents), and by scanning only samplings were carried out during oceanic electron microscope (SEM) and energy dispersive X cruises [Chester and Johnson, 1971; Parkin et ray analyzer (EDXA) examination (shape, surface al., 1972] and the results were compared to the features, and mineralogy of particles), with the marine sedimentation [Tetzlaff and Wolter, 198