Genetic diversity patterns of arbuscular mycorrhizal fungi associated with the mycoheterotroph Arachnitis uniflora Phil. (Corsiaceae)

Background and AimsArachnitis uniflora is a mycoheterotrophic plant that exploits arbuscular mycorrhizal fungi of neighbouring plants. We tested A. uniflora's specificity towards fungi across its large latitudinal range, as well as the role of historical events and current environmental, geographical and altitudinal variables on fungal genetic diversity. MethodsArachnitis uniflora mycorrhizas were sampled at 25 sites. Fungal phylogenetic relationships were reconstructed, genetic diversity was calculated and the main divergent lineages were dated. Phylogeographical analysis was performed with the main fungal clade. Fungal diversity correlations with environmental factors were investigated. Key Results Glomeraceae fungi dominated, with a main clade that likely originated in the Upper Cretaceous and diversified in the Miocene. Two other arbuscular mycorrhizal fungal families not previously known to be targeted by A. uniflora were detected rarely and appear to be facultative associations. High genetic diversity, found in Bolivia and both northern and southern Patagonia, was correlated with temperature, rainfall and soil features. Conclusions Fungal genetic diversity and its distribution can be explained by the ancient evolutionary history of the target fungi and by micro-scale environmental conditions with a geographical mosaic pattern

First molecular identification of canine Parvovirus type 2 (CPV2) in Chile reveals high occurrence of CPV2c antigenic variant

Canine parvovirus type 2 (CPV2) is one of the most important intestinal pathogens in dogs and puppies. CPV2 has been evolved into three genetic and antigenic variants (2a, 2b, and 2c), which are distributed worldwide. We reported the first study of genetic diversity of CPV2 in Chile. Sixty-five samples were collected from puppies presenting with severe gastroenteritis and different vaccination statuses. PCR, restriction fragment length polymorphism (RFLP), and partial sequencing of the coding region of the structural viral protein VP2 was performed. Thirty of a total of 65 samples tested positive by PCR out of which 19 were further classified as CPV2c and one as CPV2a using RFLP and Sanger sequencing. The phylogeny was in concordance with the RFLP analysis. This is the first report of the genetic characterization of CPV2 in Chile and reveals a high occurrence of CPV2c

3D extracellular matrix microenvironment in bioengineered tissue models of primary pediatric and adult brain tumors.

Dynamic alterations in the unique brain extracellular matrix (ECM) are involved in malignant brain tumors. Yet studies of brain ECM roles in tumor cell behavior have been difficult due to lack of access to the human brain. We present a tunable 3D bioengineered brain tissue platform by integrating microenvironmental cues of native brain-derived ECMs and live imaging to systematically evaluate patient-derived brain tumor responses. Using pediatric ependymoma and adult glioblastoma as examples, the 3D brain ECM-containing microenvironment with a balance of cell-cell and cell-matrix interactions supports distinctive phenotypes associated with tumor type-specific and ECM-dependent patterns in the tumor cells\u27 transcriptomic and release profiles. Label-free metabolic imaging of the composite model structure identifies metabolically distinct sub-populations within a tumor type and captures extracellular lipid-containing droplets with potential implications in drug response. The versatile bioengineered 3D tumor tissue system sets the stage for mechanistic studies deciphering microenvironmental role in brain tumor progression

Speed Effect on Joint Powers in Aging Gait

Ankle plantar flexor (A2), hip extensor (H1) and hip flexor (H3) joint power generation are important factors in human gait. It is well known gait speed and ageing alters joint kinetics during walking. Ageing gait has been associated with decreased ankle joint function and increased hip muscle activity. However, it is not known whether this effect of speed upon join kinetics is the same for older and young adults. This study investigated the effect of speed on A2, H1 and H3 joint powers in a group of young (YG) and older adults (OG) walking over a range of speeds. Participants walked at seven speed conditions. Peak joint powers were calculated and regressed as a function of gait speed. All joint powers were affected by speed. The OG increased H3 more than the YG, whereas the YG increased more A2 than the OG. At speeds over 1.5 ms-1 the OG increased cadence more than the YG, whereas the YG increased step length more than the OG. This shows that the OG relied more on hip flexor muscles and increases in cadence to reach a maximum walking speed

Relationship between ankle plantar flexor power and EMG muscle activity during gait

It is thought that the A2 ankle power burst observed in human gait is solely generated by rapid concentric contraction of the ankle plantar flexors. Recent work, however, suggests that the return of elastic energy may play a role. This study investigated the temporal relationship between the maximum electromyographic activity (EMG) of the ankle plantar flexors and A2. The natural gait of eight young adults were recorded across level ground. Collectively, the maximum EMG of the Soleus, Gastrocnemius and Peroneus Longus fell 92 ms before A2. The period between maximum EMG and A2 were longer than the electromechanical delay reported in the literature (e.g. 8 to 45 ms). It is reasonable to conclude, therefore, that it may be partly produced by the return of elastic energy stored in the musculotendinous units of the plantar flexors during the A1 absorption period

Aging modifies joint power and work when gait speeds are matched

It is well known that ankle joint power generation (A2) is reduced in healthy older adults (OG) during gait. No general consensus exists, however, as to what fundamental compensatory actions are made at the knee and hip joints by the OG to compensate for this loss of power. The failure to control gait speed may account for this lack of agreement. This study investigated the effect of aging on lower limb joint power and work during gait. The gait patterns of eight old (OG: 66.8±5.4yr) and 12 young adults (YG: 26.6±2.9yr) were recorded for a range of matched speeds (1.0ms-1, 1.3ms-1, 1.6ms-1). Speed did not differ between the groups. Combining speeds, the OG generated 17% less A2 power and 21% less A2 work (p<0.05). Compared to the YG, the OG generated 46% more H1 work, 30% more H2 peak power, 16% more H3 peak power, 30% more K3 peak power and 19% more K4 peak power (p<0.05). These actions by the OG were associated with less ankle plantar-flexion, more hip flexion and anterior pelvic tilt (p<0.05). The OG adopted a different gait pattern at the faster speeds by generating more H3 work than A2 work. This shows the OG rely on hip flexors to propel the leg into swing when ankle plantar-flexor function is reduced. This may partly explain how gait changes emerge with aging

Can explicit visual feedback of postural sway efface the effects of sensory manipulations on mediolateral balance performance?

Explicit visual feedback on postural sway is often used in balance assessment and training. However, up-weighting of visual information may mask impairments of other sensory systems. We therefore aimed to determine whether the effects of somatosensory, vestibular and proprioceptive manipulations on mediolateral balance are reduced by explicit visual feedback on mediolateral sway of the body center of mass and by the presence of visual information. We manipulated sensory inputs of the somatosensory system by transcutaneous electric nerve stimulation on the feet soles (TENS), of the vestibular system by galvanic vestibular stimulation (GVS) and of the proprioceptive system by muscle-tendon vibration (VMS) of hip abductors. The effects of these manipulations on mediolateral sway were compared to a control condition without manipulation under three visual conditions: explicit feedback of sway of the body center of mass (FB), eyes open (EO) and eyes closed (EC). Mediolateral sway was quantified as the sum of energies in the power spectrum and as the energy at the dominant frequencies in each of the manipulation signals. Repeated measures ANOVA were used to test effects of each of the sensory manipulations, of visual conditions and their interaction. Overall, sensory manipulations increased body sway when compared to the control conditions. Absence of normal visual information had no effect on sway, while explicit feedback reduced sway. Furthermore, interactions of visual information and sensory manipulation were found at specific dominant frequencies for GVS and VMS, with explicit feedback reducing the effects of the manipulations but not effacing these.status: publishe

Computational modelling in disorders of consciousness: closing the gap towards personalised models for restoring consciousness

Disorders of consciousness are complex conditions characterised by persistent loss of responsiveness due to brain injury. They present diagnostic challenges and limited options for treatment, and highlight the urgent need for a more thorough understanding of how human consciousness arises from coordinated neural activity. The increasing availability of multimodal neuroimaging data has given rise to a wide range of clinically- and scientifically-motivated modelling efforts, seeking to improve data-driven stratification of patients, to identify causal mechanisms for patient pathophysiology and loss of consciousness more broadly, and to develop simulations as a means of testing in silico potential treatment avenues to restore consciousness. As a dedicated Working Group of clinicians and neuroscientists of the international Curing Coma Campaign, here we provide our framework and vision to understand the diverse statistical and generative computational modelling approaches that are being employed in this fast-growing field. We identify the gaps that exist between the current state of the art in statistical and biophysical computational modelling in human neuroscience, and the aspirational goal of a mature field of modelling disorders of consciousness; which might drive improved treatments and outcomes in the clinic. Finally, we make several recommendations for how the field as a whole can work together to address these challenges