Plants often release a blend of volatile organic compounds in response to damage by herbivorous insects that may serve as cues to locate those herbivores by natural enemies. The blend of compounds ...emitted by plants may be more variable than is generally assumed. The quantity and the composition of the blends may vary with the species of the herbivore, the plant species and genotype within species, the environmental conditions under which plants are grown, and the number of herbivore species attacking the plant. Although it is often assumed that induced emission of these compounds is an adaptive tactic on the part of plants, the evidence that such responses minimize fitness losses of plants remains sparse because the necessary data on plant fitness rarely have been collected. The application of techniques of evolutionary quantitative genetics may facilitate the testing of widely held hypotheses about the evolution of induced production of volatile compounds under natural conditions.
Parkinson's disease prevalence is rapidly increasing in an aging global population. With this increase comes exponentially rising social and economic costs, emphasizing the immediate need for ...effective disease‐modifying treatments. Motor dysfunction results from the loss of dopaminergic neurons in the substantia nigra pars compacta and depletion of dopamine in the nigrostriatal pathway. While a specific biochemical mechanism remains elusive, oxidative stress plays an undeniable role in a complex and progressive neurodegenerative cascade. This review will explore the molecular factors that contribute to the high steady‐state of oxidative stress in the healthy substantia nigra during aging, and how this chemical environment renders neurons susceptible to oxidative damage in Parkinson's disease. Contributing factors to oxidative stress during aging and as a pathogenic mechanism for Parkinson's disease will be discussed within the context of how and why therapeutic approaches targeting cellular redox activity in this disorder have, to date, yielded little therapeutic benefit. We present a contemporary perspective on the central biochemical contribution of redox imbalance to Parkinson's disease etiology and argue that improving our ability to accurately measure oxidative stress, dopaminergic neurotransmission and cell death pathways in vivo is crucial for both the development of new therapies and the identification of novel disease biomarkers.
Dopamine neurons within the healthy human substantia nigra exhibit mild oxidative stress during aging, resulting from their unique biochemical properties and a number of age‐dependent biochemical changes specific to this neuronal population (grey). An exacerbation of these pathways, combined with additional environmental toxins and genetic mutations, worsens redox balance within nigral dopamine neurons in Parkinson's disease, causing excessive oxidative stress and dopamine neuron death (red).
Glutathione peroxidase 4 (GPx4) is an antioxidant enzyme reported as an inhibitor of ferroptosis, a recently discovered non-apoptotic form of cell death. This pathway was initially described in ...cancer cells and has since been identified in hippocampal and renal cells. In this Perspective, we propose that inhibition of ferroptosis by GPx4 provides protective mechanisms against neurodegeneration. In addition, we suggest that selenium deficiency enhances susceptibility to ferroptotic processes, as well as other programmed cell death pathways due to a reduction in GPx4 activity. We review recent studies of GPx4 with an emphasis on neuronal protection, and discuss the relevance of selenium levels on its enzymatic activity.
The relationship between neurons and perineuronal nets (PNNs) is attracting attention as a central mechanism controlling brain plasticity. In the cortex, PNNs primarily surround inhibitory ...parvalbumin interneurons, playing roles as both a regulator of synaptic plasticity and a protective barrier. PNNs have a delayed developmental trajectory and are key components in the closure of critical periods of heightened neuroplasticity. In animal models, manipulating PNNs outside this critical window can enhance cognition, suggesting a potentially therapeutic approach for attenuating cognitive decline. However, the crucial role of PNNs in plasticity and protection means that such therapeutic modulation must strike a careful balance: manipulation of PNNs to promote plasticity may have unintended negative consequences resulting from excessive plasticity or from exposure of neurons to neurotoxins.
Perineuronal nets (PNNs) are extracellular matrix structures serving multiple functions, including regulating synaptic plasticity, stabilizing synapses, and protecting neurons from oxidative stress and neurotoxins.Through their physiological roles, PNNs are also involved in cognition – including encoding, maintaining, and updating memories.Removal of PNNs can render neurons vulnerable to damage – particularly in neurodegenerative conditions involving increased oxidative stress or neurotoxins.Removal or digestion of PNNs in animal models increases plasticity, leading to enhanced memory interference from competing information during the encoding process.Environmental factors, such as physical activity, drugs, and nutrition, can influence brain plasticity, and some of these effects may be mediated by changes in PNN structure.Defining molecular targets that modify PNN structure may aid development of interventions for individuals experiencing cognitive decline linked to aberrant neural plasticity, such as in dementia.
An eco-evolutionary feedback loop is defined as the reciprocal impacts of ecology on evolutionary dynamics and evolution on ecological dynamics on contemporary timescales. We experimentally tested ...for an eco-evolutionary feedback loop in the green peach aphid,Myzus persicae, by manipulating initial densities and evolution. We found strong evidence that initial aphid density alters the rate and direction of evolution, as measured by changes in genotype frequencies through time. We also found that evolution of aphids within only 16 days, or approximately three generations, alters the rate of population growth and predicts density compared to nonevolving controls. The impact of evolution on population dynamics also depended on density. In one evolution treatment, evolution accelerated population growth by up to 10.3% at high initial density or reduced it by up to 6.4% at low initial density. The impact of evolution on population growth was as strong as or stronger than that caused by a threefold change in intraspecific density. We found that, taken together, ecological condition, here intraspecific density, alters evolutionary dynamics, which in turn alter concurrent population growth rate (ecological dynamics) in an eco-evolutionary feedback loop. Our results suggest that ignoring evolution in studies predicting population dynamics might lead us to over- or underestimate population density and that we cannot predict the evolutionary outcome within aphid populations without considering population size.
Abstract
The
13
C/
12
C ratio of C
3
plant matter is thought to be controlled by the isotopic composition of atmospheric CO
2
and stomatal response to environmental conditions, particularly mean ...annual precipitation (MAP). The effect of CO
2
concentration on
13
C/
12
C ratios is currently debated, yet crucial to reconstructing ancient environments and quantifying the carbon cycle. Here we compare high-resolution ice core measurements of atmospheric CO
2
with fossil plant and faunal isotope records. We show the effect of pCO
2
during the last deglaciation is stronger for gymnosperms (−1.4 ± 1.2‰) than angiosperms/fauna (−0.5 ± 1.5‰), while the contributions from changing MAP are −0.3 ± 0.6‰ and −0.4 ± 0.4‰, respectively. Previous studies have assumed that plant
13
C/
12
C ratios are mostly determined by MAP, an assumption which is sometimes incorrect in geological time. Atmospheric effects must be taken into account when interpreting terrestrial stable carbon isotopes, with important implications for past environments and climates, and understanding plant responses to climate change.
The apolipoprotein B mRNA-editing enzyme, catalytic polypeptide-like (APOBEC) mutational signature has only recently been detected in a multitude of cancers through next-generation sequencing. In ...contrast, APOBEC has been a focus of virology research for over a decade. Many lessons learnt regarding APOBEC within virology are likely to be applicable to cancer. In this review, we explore the parallels between the role of APOBEC enzymes in HIV and cancer evolution. We discuss data supporting the role of APOBEC mutagenesis in creating HIV genome heterogeneity, drug resistance, and immune escape variants. We hypothesize similar functions of APOBEC will also hold true in cancer.
We present a detailed study of magnetic reconnection in a quasi-two-dimensional pulsed-power driven laboratory experiment. Oppositely directed magnetic fields (B=3 T), advected by supersonic, ...sub-Alfvénic carbon plasma flows (V_{in}=50 km/s), are brought together and mutually annihilate inside a thin current layer (δ=0.6 mm). Temporally and spatially resolved optical diagnostics, including interferometry, Faraday rotation imaging, and Thomson scattering, allow us to determine the structure and dynamics of this layer, the nature of the inflows and outflows, and the detailed energy partition during the reconnection process. We measure high electron and ion temperatures (T_{e}=100 eV, T_{i}=600 eV), far in excess of what can be attributed to classical (Spitzer) resistive and viscous dissipation. We observe the repeated formation and ejection of plasmoids, consistent with the predictions from semicollisional plasmoid theory.
Metal biochemistry drives a diverse range of cellular processes associated with development, health and disease. Determining metal distribution, concentration and flux defines our understanding of ...these fundamental processes. A comprehensive analysis of biological systems requires a balance of analytical techniques that inform on metal quantity (sensitivity), chemical state (selectivity) and location (spatial resolution) with a high degree of certainty. A number of approaches are available for imaging metals from whole tissues down to subcellular organelles, as well as mapping metal turnover, protein association and redox state within these structures. Technological advances in micro- and nano-scale imaging are striving to achieve multi-dimensional and in vivo measures of metals while maintaining the native biochemical environment and physiological state. This Tutorial Review discusses state-of-the-art imaging technology as a guide to obtaining novel insight into the biology of metals, with sensitivity, selectivity and spatial resolution in focus.
Repurposing of CO2 to valuable hydrocarbons is crucial for energy security and a balanced carbon cycle. Reverse water gas shift chemical looping (RWGS-CL) is capable of efficient CO2 to CO conversion ...at a low temperature of ∼600 °C with unprecedented rates using the La0.75Sr0.25FeO3 (LSF) perovskite-type oxide amalgamated with silica. The LSF/SiO2 composite (25% LSF by mass) promotes a notable extent of oxygen vacancies in the active phase, a key parameter for CO2 conversion. In each of eight RWGS-CL cycles, CO generation yields of LSF/SiO2 surpass those of LSF alone by about 200%, producing 2.6 mmol of CO gLSF –1 at a peak rate of 0.8 mmol CO gLSF –1 min–1. This significant improvement is concomitant with a decreased average LSF crystallite size retained at these low thermochemical reaction temperatures. Evidence of this enhancement points to perovskite particle size reduction by silica, lattice strain induced by the support, and curtailed quantities of secondary phases that limit accessibility to active surfaces. In this contribution, an appropriate stable platform for improving earth abundancy in perovskite-based redox materials is demonstrated for industrial-scale low-temperature CO2 thermochemical conversion.
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