Ancient DNA of the pygmy marmoset type specimen Cebuella pygmaea (Spix, 1823) resolves a taxonomic conundrum

The pygmy marmoset, the smallest of the anthropoid primates, has a broad distribution in Western Amazonia. Recent studies using molecular and morphological data have identified two distinct species separated by the Napo and Solimões-Amazonas rivers. However, reconciling this new biological evidence with current taxonomy, i.e., two subspecies, Cebuella pygmaea pygmaea (Spix, 1823) and Cebuella pygmaea niveiventris (Lönnberg, 1940), was problematic given the uncertainty as to whether Spix’s pygmy marmoset (Cebuella pygmaea pygmaea) was collected north or south of the Napo and Solimões-Amazonas rivers, making it unclear to which of the two newly revealed species the name pygmaea would apply. Here, we present the first molecular data from Spix’s type specimen of Cebuella pygmaea, as well as novel mitochondrial genomes from modern pygmy marmosets sampled near the type locality (Tabatinga) on both sides of the river. With these data, we can confirm the correct names of the two species identified, i.e., C. pygmaea for animals north of the Napo and Solimões-Amazonas rivers and C. niveiventris for animals south of these two rivers. Phylogenetic analyses of the novel genetic data placed into the context of cytochrome b gene sequences from across the range of pygmy marmosets further led us to re-evaluate the geographical distribution for the two Cebuella species. We dated the split of these two species to 2.54 million years ago. We discuss additional, more recent, subdivisions within each lineage, as well as potential contact zones between the two species in the headwaters of these rivers

Action to protect the independence and integrity of global health research

Storeng KT, Abimbola S, Balabanova D, et al. Action to protect the independence and integrity of global health research. BMJ GLOBAL HEALTH. 2019;4(3): e001746

Leukodystrophies: a proposed classification system based on pathological changes and pathogenetic mechanisms

Leukodystrophies are genetically determined disorders characterized by the selective involvement of the central nervous system white matter. Onset may be at any age, from prenatal life to senescence. Many leukodystrophies are degenerative in nature, but some only impair white matter function. The clinical course is mostly progressive, but may also be static or even improving with time. Progressive leukodystrophies are often fatal, and no curative treatment is known. The last decade has witnessed a tremendous increase in the number of defined leukodystrophies also owing to a diagnostic approach combining magnetic resonance imaging pattern recognition and next generation sequencing. Knowledge on white matter physiology and pathology has also dramatically built up. This led to the recognition that only few leukodystrophies are due to mutations in myelin- or oligodendrocyte-specific genes, and many are rather caused by defects in other white matter structural components, including astrocytes, microglia, axons and blood vessels. We here propose a novel classification of leukodystrophies that takes into account the primary involvement of any white matter component. Categories in this classification are the myelin disorders due to a primary defect in oligodendrocytes or myelin (hypomyelinating and demyelinating leukodystrophies, leukodystrophies with myelin vacuolization); astrocytopathies; leuko-axonopathies; microgliopathies; and leuko-vasculopathies. Following this classification, we illustrate the neuropathology and disease mechanisms of some leukodystrophies taken as example for each category. Some leukodystrophies fall into more than one category. Given the complex molecular and cellular interplay underlying white matter pathology, recognition of the cellular pathology behind a disease becomes crucial in addressing possible treatment strategies

Geometric morphometrics and finite element analyses reveal the Haast's eagle (Harpagornis moorei) to be a mixed predator-scavenger

The extinct Haast’s eagle (Harpagornis moorei) was 30-40% heavier than the largest extant eagle. There have been speculations about its evolutionary history and ecology, though there is still no consensus on its feeding behaviour. This study aims at understanding the evolution and ecology of Harpagornis by combining 3D geometric morphometrics and finite element analysis (FEA) on three-dimensional models constructed from CT-data of skulls and talons of Accipitridae. Statistical analyses revealed the presence of two independent modules (beak and neurocranium) and of a strong allometric effect in the skull. Size-free shape analysis of the two modules revealed that Harpagornis’ beak was similar to the eagles, while it’s neurocranial morphology was more like a vulture. In most cranial FEA loading cases, there seems to be a dichotomy between Cathartidae on the one side and Accipitridae on the other. FEA on the skull, nevertheless, indicates that Harpagornis and the scavenging species of our dataset are well adapted to perform a pull-back motion. The talon results suggest Harpagornis was an active hunter. Harpagornis’ talon occupies a position in morphospace close to its closest living relative Hieraaetus (smallest extant eagle), suggesting a phylogenetic constraint on talon shape. However, FEA showed that the talon of Harpagornis undergoes similar stresses to that of other hunting raptors which rely on large-sized prey (e.g. Aquila audax). Neurocranial morphology and FEA, however, clearly indicate a feeding behaviour more similar to vultures, possibly because of the large size of its prey (e.g., giant Moa). Harpagornis’ neurocranial adaptation probably allowed a stronger and faster pull back motion to quickly remove large chunks of meat from the prey, similarly to vultures. Moreover, our results document a rapid evolutionary change, which might have allowed Harpagornis to exploit large sized prey. Harpagornis moorei therefore represents an extreme example of how freedom from competition in island ecosystems can rapidly influence morphological adaptation