A new, transportable ergometer for the measurement of musculotendinous stiffness during wrist flexion.

We present here a new, dedicated mechanical device for monitoring quick-release movements of the wrist. The ergometer was designed to easily assess musculotendinous properties during wrist flexion. Maximal voluntary contractions (MVC) and quick-release (QR) movements during wrist flexion were performed on 14 subjects. A validation of the ergometer, using a test-retest methodology, was performed to assess its reliability and sensitivity. The device has been technically and biomechanically validated in a range of situations, including inertia measurement (mean inertia was found 0.0119+/-0.0012 N m s(2) rad(-1)) and appearance of the unloading reflex. Our results indicate that the device provides highly reliable, sensitive evaluation of wrist muscle stiffness (intraclass correlation coefficient for inertia, maximal voluntary contraction and stiffness index were 0.873, 0.994 and 0.930, respectively). Its portability facilitates measurement of the influence of repetitive, occupational activity on the musculotendinous complex of the wrist flexors.     

WOX14 promotes bioactive gibberellin synthesis and vascular cell differentiation in Arabidopsis

Procambial and cambial stem cells provide the initial cells that allow the formation of vascular tissues. WOX4 and WOX14 have been shown to act redundantly to promote procambial cell proliferation and differentiation. Gibberellins (GAs), which have an important role in wood formation, also stimulate cambial cell division. Here we show that the loss of WOX14 function phenocopies some traits of GA‐deficient mutants that can be complemented by exogenous GA application, whereas WOX14 overexpression stimulates the expression of GA3ox anabolism genes and represses GA2ox catabolism genes, promoting the accumulation of bioactive GA. More importantly, our data clearly indicate that WOX14 but not WOX4 promotes vascular cell differentiation and lignification in inflorescence stems of Arabidopsis.     

Genetic divergence within the monotypic tree genus <Emphasis Type="Italic">Platycarya</Emphasis> (Juglandaceae) and its implications for species’ past dynamics in subtropical China

Subtropical East Asia harbours a large plant diversity that is often attributed to allopatric speciation in this topographically complex region characterized by a relative climate stability. Here, we use observations of Platycarya, a widespread subtropical Asian tree genus, to explore the consequences of past climate stability on species’ evolutionary history in subtropical China. This genus has a controversial taxonomy: while it is now prevailingly treated as monotypic, two species have been originally described, Platycarya strobilacea and P. longipes. Previous information from species distribution models, fossil pollen data and genetic data based on chloroplast DNA (cpDNA) were integrated with newly obtained genetic data from the two putative species. We used both cpDNA (psbA-trnH and trnL-F intergenic spacers, including a partial trnL gene sequence) and nuclear markers. The latter included sequences of the internal transcribed spacer region (ITS1–5.8S–ITS2) of the nuclear ribosomal DNA and random genomic single nucleotide polymorphisms. Using these nuclear genetic markers, we found interspecific genetic divergence fitting with the ‘two species’ scenario and geographically structured intraspecific variation. Using cpDNA markers, we also found geographically structured intraspecific variation. Despite deep inter- and intraspecific genetic divergence, we detected genetic admixture in southwest China. Overall, our findings of genetic divergence within Platycarya support the hypothesis of allopatric speciation. However, episodes of population interconnection were identified, at least in southwest China, suggesting that the genus has had a dynamic population history.     

Lysosomal dysfunction in Parkinson disease: ATP13A2 gets into the groove

Mutations in ATP13A2 (PARK9) cause an autosomal recessive form of early-onset parkinsonism with pyramidal degeneration and dementia called Kufor-Rakeb Syndrome (KRS). The ATP13A2 gene encodes a transmembrane lysosomal P5-type ATPase (ATP13A2) whose physiological function in mammalian cells, and hence its potential role in Parkinson disease (PD), remains elusive. In this context, we have recently shown that KRS-linked mutations in ATP13A2 leads to several lysosomal alterations in ATP13A2 KRS patient-derived fibroblasts, including impaired lysosomal acidification, decreased proteolytic processing of lysosomal enzymes, reduced degradation of lysosomal substrates and diminished lysosomal-mediated clearance of autophagosomes (AP). Similar alterations are observed in stable ATP13A2-knockdown dopaminergic cell lines, which are associated with cell death. Restoration of ATP13A2 levels in ATP13A2-mutant/depleted cells is able to restore lysosomal function and attenuate cell death. Relevant to PD, we have determined that ATP13A2 levels are decreased in dopaminergic nigral neurons from sporadic PD patients. Interestingly in these patients, the main signal of ATP13A2 is detected in the Lewy bodies. Our results unravel an instrumental role of ATP13A2 in lysosomal function and in cell viability. Altogether, our results validate ATP13A2 as a likely therapeutic target against PD degeneration.     

High‐Throughput DNA sequencing of ancient wood

Reconstructing the colonization and demographic dynamics that gave rise to extant forests is essential to forecasts of forest responses to environmental changes. Classical approaches to map how population of trees changed through space and time largely rely on pollen distribution patterns, with only a limited number of studies exploiting DNA molecules preserved in wooden tree archaeological and subfossil remains. Here, we advance such analyses by applying high‐throughput (HTS) DNA sequencing to wood archaeological and subfossil material for the first time, using a comprehensive sample of 167 European white oak waterlogged remains spanning a large temporal (from 550 to 9,800 years) and geographical range across Europe. The successful characterization of the endogenous DNA and exogenous microbial DNA of 140 (~83%) samples helped the identification of environmental conditions favouring long‐term DNA preservation in wood remains, and started to unveil the first trends in the DNA decay process in wood material. Additionally, the maternally inherited chloroplast haplotypes of 21 samples from three periods of forest human‐induced use (Neolithic, Bronze Age and Middle Ages) were found to be consistent with those of modern populations growing in the same geographic areas. Our work paves the way for further studies aiming at using ancient DNA preserved in wood to reconstruct the micro‐evolutionary response of trees to climate change and human forest management.     

Immune gene variability influences roe deer natal dispersal

Dispersal is a key life‐history trait governing the response of individuals, populations and species to changing environmental conditions. In the context of global change, it is therefore essential to better understand the respective role of condition‐, phenotype‐ and genetic‐dependent drivers of dispersal behaviour. Although the importance of immune function and pathogen infestation in determining patterns of dispersal is increasingly recognised, no study to our knowledge has yet investigated the influence of immune gene variability on dispersal behaviour. Here, we filled this knowledge gap by assessing whether individual heterozygosity at five immune gene loci (one from the Major histocompatibility complex and four from encoding Toll‐like receptors) influences roe deer natal dispersal. We found that dispersal propensity was affected by immune gene diversity, suggesting potential pathogen‐mediated selection through over‐dominance. However, the direction of this effect differed between high and low quality individuals, suggesting that dispersal propensity is driven by two different mechanisms. In support of the condition‐dependent dispersal hypothesis, dispersal propensity increased with increasing body mass and, among high quality individuals only (standardized body mass > 18 kg), with increasing immune gene diversity. However, among poor quality individuals, we observed the opposite pattern such that dispersal propensity was higher for individuals with lower immune gene diversity. We suggest that these poor quality individuals expressed an emergency dispersal tactic in an attempt to escape a heavily infested environment associated with poor fitness prospects. Our results have potentially important consequences in terms of population genetics and demography, as well as host–pathogen evolution.     

Immunogenetic heterogeneity in a widespread ungulate: the European roe deer (Capreolus capreolus)

Understanding how immune genetic variation is shaped by selective and neutral processes in wild populations is of prime importance in both evolutionary biology and epidemiology. The European roe deer (Capreolus capreolus) has considerably expanded its distribution range these last decades, notably by colonizing agricultural landscapes. This range shift is likely to have led to bottlenecks and increased roe deer exposure to a new range of pathogens that until recently predominantly infected humans and domestic fauna. We therefore investigated the historical and contemporary forces that have shaped variability in a panel of genes involved in innate and acquired immunity in roe deer, including Mhc‐Drb and genes encoding cytokines or toll‐like receptors (TLRs). Together, our results suggest that genetic drift is the main contemporary evolutionary force shaping immunogenetic variation within populations. However, in contrast to the classical view, we found that some innate immune genes involved in micropathogen recognition (e.g. Tlrs) continue to evolve dynamically in roe deer in response to pathogen‐mediated positive selection. Most studied Tlrs (Tlr2, Tlr4 and Tlr5) had similarly high levels of amino acid diversity in the three studied populations including one recently established in southwestern France that showed a clear signature of genetic bottleneck. Tlr2 implicated in the recognition of Gram‐positive bacteria in domestic ungulates, showed strong evidence of balancing selection. The high immunogenetic variation revealed here implies that roe deer are able to cope with a wide spectrum of pathogens and to respond rapidly to emerging infectious diseases.     

ERK is involved in the reorganization of somatosensory cortical maps in adult rats submitted to hindlimb unloading

Sensorimotor restriction by a 14-day period of hindlimb unloading (HU) in the adult rat induces a reorganization of topographic maps and receptive fields. However, the underlying mechanisms are still unclear. Interest was turned towards a possible implication of intracellular MAPK signaling pathway since Extracellular-signal-Regulated Kinase 1/2 (ERK1/2) is known to play a significant role in the control of synaptic plasticity. In order to better understand the mechanisms underlying cortical plasticity in adult rats submitted to a sensorimotor restriction, we analyzed the time-course of ERK1/2 activation by immunoblot and of cortical reorganization by electrophysiological recordings, on rats submitted to hindlimb unloading over four weeks. Immunohistochemistry analysis provided evidence that ERK1/2 phosphorylation was increased in layer III neurons of the somatosensory cortex. This increase was transient, and parallel to the changes in hindpaw cortical map area (layer IV). By contrast, receptive fields were progressively enlarged from 7 to 28 days of hindlimb unloading. To determine whether ERK1/2 was involved in cortical remapping, we administered a specific ERK1/2 inhibitor (PD-98059) through osmotic mini-pump in rats hindlimb unloaded for 14 days. Results demonstrate that focal inhibition of ERK1/2 pathway prevents cortical reorganization, but had no effect on receptive fields. These results suggest that ERK1/2 plays a role in the induction of cortical plasticity during hindlimb unloading.