Molecular genetic tools have had a profound impact on neuroscience, but until recently their application has largely been confined to a few model species, most notably mouse, zebrafish, Drosophila ...melanogaster and Caenorhabditis elegans. With the development of new genome engineering technologies such as CRISPR, it is becoming increasingly feasible to apply these molecular tools in a wider range of species, including nonhuman primates. This will lead to many opportunities for brain research, but it will also pose challenges. Here we identify some of these opportunities and challenges in light of recent and foreseeable technological advances and offer some suggestions. Our main focus is on the creation of new primate disease models for understanding the pathological mechanisms of brain disorders and for developing new approaches to effective treatment. However, we also emphasize that primate genetic models have great potential to address many fundamental questions about brain function, providing an essential foundation for future progress in disease research.
The data-driven discovery of partial differential equations (PDEs) consistent with spatiotemporal data is experiencing a rebirth in machine learning research. Training deep neural networks to learn ...such data-driven partial differential operators requires extensive spatiotemporal data. For learning coarse-scale PDEs from computational fine-scale simulation data, the training data collection process can be prohibitively expensive. We propose to transformatively facilitate this training data collection process by linking machine learning (here, neural networks) with modern multiscale scientific computation (here, equation-free numerics). These equation-free techniques operate over sparse collections of small, appropriately coupled, space-time subdomains (“patches”), parsimoniously producing the required macro-scale training data. Our illustrative example involves the discovery of effective homogenized equations in one and two dimensions, for problems with fine-scale material property variations. The approach holds promise towards making the discovery of accurate, macro-scale effective materials PDE models possible by efficiently summarizing the physics embodied in “the best” fine-scale simulation models available.
To characterize the trabeculated connective tissue microarchitecture of the lamina cribrosa (LC) in terms of total connective tissue volume (CTV), connective tissue volume fraction (CTVF), ...predominant beam orientation, and material anisotropy in monkeys with early experimental glaucoma (EG).
The optic nerve heads from three monkeys with unilateral EG and four bilaterally normal monkeys were three dimensionally reconstructed from tissues perfusion fixed at an intraocular pressure of 10 mm Hg. A three-dimensional segmentation algorithm was used to extract a binary, voxel-based representation of the porous LC connective tissue microstructure that was regionalized into 45 subvolumes, and the following quantities were calculated: total CTV within the LC, mean and regional CTVF, regional predominant beam orientation, and mean and regional material anisotropy.
Regional variation within the laminar microstructure was considerable within the normal eyes of all monkeys. The laminar connective tissue was generally most dense in the central and superior regions for the paired normal eyes, and laminar beams were radially oriented at the periphery for all eyes considered. CTV increased substantially in EG eyes compared with contralateral normal eyes (82%, 44%, 45% increases; P<0.05), but average CTVF changed little (-7%, 1%, and -2% in the EG eyes). There were more laminar beams through the thickness of the LC in the EG eyes than in the normal controls (46%, 18%, 17% increases).
The substantial increase in laminar CTV with little change in CTVF suggests that significant alterations in connective and nonconnective tissue components in the laminar region occur in the early stages of glaucomatous damage.
Summary
The increasing demand for food production and predicted climate change scenarios highlight the need for improvements in crop sustainability. The efficient use of water will become ...increasingly important for rain‐fed agricultural crops even in fertile regions that have historically received ample precipitation. Improvements in water‐use efficiency in Zea mays have been limited, and warrant a renewed effort aided by molecular breeding approaches. Progress has been constrained by the difficulty of measuring water‐use in a field environment. The stable carbon isotope composition (δ13C) of the leaf has been proposed as an integrated signature of carbon fixation with a link to stomatal conductance. However, additional factors affecting leaf δ13C exist, and a limited number of studies have explored this trait in Z. mays. Here we present an extensive characterization of leaf δ13C in Z. mays. Significant variation in leaf δ13C exists across diverse lines of Z. mays, which we show to be heritable across several environments. Furthermore, we examine temporal and spatial variation in leaf δ13C to determine the optimum sampling time to maximize the use of leaf δ13C as a trait. Finally, our results demonstrate the relationship between transpiration and leaf δ13C in the field and the greenhouse. Decreasing transpiration and soil moisture are associated with decreasing leaf δ13C. Taken together these results outline a strategy for using leaf δ13C and reveal its usefulness as a measure of transpiration efficiency under well‐watered conditions rather than a predictor of performance under drought.
Significance Statement
This study identifies sources of variation in stable carbon isotopes of maize leaves, and establishes the framework for connecting leaf δ13C and transpiration efficiency.
Plasmodium parasites cause malaria and are responsible annually for hundreds of thousands of deaths. Kinesins are a superfamily of microtubule-dependent ATPases that play important roles in the ...parasite replicative machinery, which is a potential target for antiparasite drugs. Kinesin-5, a molecular motor that cross-links microtubules, is an established antimitotic target in other disease contexts, but its mechanism in Plasmodium falciparum is unclear. Here, we characterized P. falciparum kinesin-5 (PfK5) using cryo-EM to determine the motor's nucleotide-dependent microtubule-bound structure and introduced 3D classification of individual motors into our microtubule image processing pipeline to maximize our structural insights. Despite sequence divergence in PfK5, the motor exhibits classical kinesin mechanochemistry, including ATP-induced subdomain rearrangement and cover neck bundle formation, consistent with its plus-ended directed motility. We also observed that an insertion in loop5 of the PfK5 motor domain creates a different environment in the well-characterized human kinesin-5 drug-binding site. Our data reveal the possibility for selective inhibition of PfK5 and can be used to inform future exploration of Plasmodium kinesins as antiparasite targets.
BMP9 (bone morphogenetic protein 9) is a circulating endothelial quiescence factor with protective effects in pulmonary arterial hypertension (PAH). Loss-of-function mutations in BMP9, its receptors, ...and downstream effectors have been reported in heritable PAH.
To determine how an acquired deficiency of BMP9 signaling might contribute to PAH.
Plasma levels of BMP9 and antagonist soluble endoglin were measured in group 1 PAH, group 2 and 3 pulmonary hypertension (PH), and in patients with severe liver disease without PAH.
BMP9 levels were markedly lower in portopulmonary hypertension (PoPH) versus healthy control subjects, or other etiologies of PAH or PH; distinguished PoPH from patients with liver disease without PAH; and were an independent predictor of transplant-free survival. BMP9 levels were decreased in mice with PH associated with CCl
-induced portal hypertension and liver cirrhosis, but were normal in other rodent models of PH. Administration of ALK1-Fc, a BMP9 ligand trap consisting of the activin receptor-like kinase-1 extracellular domain, exacerbated PH and pulmonary vascular remodeling in mice treated with hypoxia versus hypoxia alone.
BMP9 is a sensitive and specific biomarker of PoPH, predicting transplant-free survival and the presence of PAH in liver disease. In rodent models, acquired deficiency of BMP9 signaling can predispose to or exacerbate PH, providing a possible mechanistic link between PoPH and heritable PAH. These findings describe a novel experimental model of severe PH that provides insight into the synergy between pulmonary vascular injury and diminished BMP9 signaling in the pathogenesis of PAH.
Background: PTSD self-report measures are frequently used in mental health services but very few have been evaluated in clinical samples that include civilians. The PCL-5 was developed to assess for ...DSM-5 PTSD.
Objective: The aim of this study was to evaluate the psychometric properties of the PCL-5 in a sample of trauma-exposed mental health service users who were evidencing symptoms of PTSD.
Method: Reliability and validity of the PCL-5 were investigated in a sample of 273 participants who reported past diagnosis for PTSD or who had screened positively for traumatic stress symptoms. Diagnostic utility was evaluated in comparison to the Clinician-Administered PTSD Scale for DSM-5 (CAPS-5).
Results: The PCL-5 demonstrated high internal consistency, good convergent and divergent validity, acceptable stability and good diagnostic utility. However, operating characteristics differed from those found in other samples. Scores of 43-44 provided optimal efficiency for diagnosing PTSD. A post hoc regression analysis showed that depression explained more of the variance in PCL-5 total score than the CAPS-5.
Conclusion: Whilst the PCL-5 is psychometrically sound it appears to have difficulty differentiating self-reported depression and anxiety symptoms from PTSD in trauma-exposed mental health service users and clinicians should take care to assess full symptomatology when individuals screen positively on the PCL-5. Clinicians and researchers should also take care not to assume that operating characteristics of self-report PTSD measures are valid for mental health service users, when these have been established in other populations.
* The PCL-5 demonstrated good psychometric properties in this sample of trauma-exposed mental health service users.
* An optimal cut off score of 43-44 was higher than reported in other studies evaluating the PCL-5.
* A post-hoc analysis suggested that the PCL-5 has difficulty differentiating self-reported depression and anxiety symptoms from PTSD.
* Clinicians should undertake further assessment to establish differential diagnosis when PCL-5 scores are raised.
Mechanical alloying was employed to produce a nanostructured Mo25Nb25Ta25W25 multi-principal element alloy (MPEA) with enhanced mechanical properties. Overall, a 400% increase in hardness was ...achieved, as compared to similar cast alloys, via mechanical alloying and optimized long-term annealing treatments. Furthermore, advanced characterization, including aberration-corrected scanning transmission electron microscopy, was conducted to elucidate processing-structure-property relationships in which it was determined that, although the introduction of impurities via mechanical alloying is common and thought to be deleterious, impurities can lead to an impressive enhancement of mechanical properties. More specifically, in this study, Fe and N impurities resulted in the formation of nanoscale, ceramic secondary phases. The observed strengthening was attributed, at least in part, to the ceramic impurity phases. Overall, we suggest that a deliberate doping strategy may be employed in the future to tailor MPEA chemistry and thereby achieve superior mechanical properties.
Dynein-2 is a large multiprotein complex that powers retrograde intraflagellar transport (IFT) of cargoes within cilia/flagella, but the molecular mechanism underlying this function is still ...emerging. Distinctively, dynein-2 contains two identical force-generating heavy chains that interact with two different intermediate chains (WDR34 and WDR60). Here, we dissect regulation of dynein-2 function by WDR34 and WDR60 using an integrative approach including cryo-electron microscopy and CRISPR/Cas9-enabled cell biology. A 3.9 Å resolution structure shows how WDR34 and WDR60 use surprisingly different interactions to engage equivalent sites of the two heavy chains. We show that cilia can assemble in the absence of either WDR34 or WDR60 individually, but not both subunits. Dynein-2-dependent distribution of cargoes depends more strongly on WDR60, because the unique N-terminal extension of WDR60 facilitates dynein-2 targeting to cilia. Strikingly, this N-terminal extension can be transplanted onto WDR34 and retain function, suggesting it acts as a flexible tether to the IFT “trains” that assemble at the ciliary base. We discuss how use of unstructured tethers represents an emerging theme in IFT train interactions.
Synopsis
Dynein-2 is the molecular motor responsible for intraflagellar transport (IFT) from the tip of cilia to the base. Here, a combination of cryo-electron microscopy, crystallography, genome editing, and live-cell imaging defines the contribution of heterodimeric intermediate chains (WDR34 and WDR60) to dynein-2 cellular function.
WDR34 and WDR60 use distinct interactions to engage equivalent sites of the two dynein-2 motor subunits.
Cilia can assemble in the absence of either WDR34 or WDR60, but not when both subunits are missing.
Dynein-2 function depends more strongly on WDR60, whose unique N-terminal extension facilitates dynein-2 targeting to cilia.
This N-terminal extension can be transplanted onto WDR34 and retain function, suggesting it acts as a flexible tether to IFT complexes assembling at the ciliary base.
The N-terminal extension of dynein-2 intermediate chain WDR60 tethers dynein-2 to intraflagellar transport complexes in cilia.
Cytoplasmic dynein powers intracellular movement of cargo toward the microtubule minus end. The first step in a variety of dynein transport events is the targeting of dynein to the dynamic ...microtubule plus end, but the molecular mechanism underlying this spatial regulation is not understood. Here, we reconstitute dynein plus-end transport using purified proteins from S. cerevisiae and dissect the mechanism using single-molecule microscopy. We find that two proteins-homologs of Lis1 and Clip170-are sufficient to couple dynein to Kip2, a plus-end-directed kinesin. Dynein is transported to the plus end by Kip2, but is not a passive passenger, resisting its own plus-end-directed motion. Two microtubule-associated proteins, homologs of Clip170 and EB1, act as processivity factors for Kip2, helping it overcome dynein's intrinsic minus-end-directed motility. This reveals how a minimal system of proteins transports a molecular motor to the start of its track.DOI: http://dx.doi.org/10.7554/eLife.02641.001.
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