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"Griffiths, S."
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Root ethylene mediates rhizosphere microbial community reconstruction when chemically detecting cyanide produced by neighbouring plants
Background
Stress-induced hormones are essential for plants to modulate their microbiota and dynamically adjust to the environment. Despite the emphasis of the role of the phytohormone ethylene in the plant physiological response to heterospecific neighbour detection, less is known about how this activated signal mediates focal plant rhizosphere microbiota to enhance plant fitness. Here, using 3 years of peanut (
Arachis hypogaea
L.), a legume, and cyanide-containing cassava (
Manihot esculenta
Crantz) intercropping and peanut monocropping field, pot and hydroponic experiments in addition to exogenous ethylene application and soil incubation experiments, we found that ethylene, a cyanide-derived signal, is associated with the chemical identification of neighbouring cassava and the microbial re-assemblage in the peanut rhizosphere.
Results
Ethylene production in peanut roots can be triggered by cyanide production of neighbouring cassava plants. This gaseous signal alters the microbial composition and re-assembles the microbial co-occurrence network of peanut by shifting the abundance of an actinobacterial species,
Catenulispora
sp., which becomes a keystone in the intercropped peanut rhizosphere. The re-assembled rhizosphere microbiota provide more available nutrients to peanut roots and support seed production.
Conclusions
Our findings suggest that root ethylene acts as a signal with a dual role. It plays a role in perceiving biochemical cues from interspecific neighbours, and also has a regulatory function in mediating the rhizosphere microbial assembly, thereby enhancing focal plant fitness by improving seed production. This discovery provides a promising direction to develop novel intercropping strategies for targeted manipulations of the rhizosphere microbiome through phytohormone signals.
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Video abstract.
Journal Article
Gradient boosted decision trees reveal nuances of auditory discrimination behavior
Animal psychophysics can generate rich behavioral datasets, often comprised of many 1000s of trials for an individual subject. Gradient-boosted models are a promising machine learning approach for analyzing such data, partly due to the tools that allow users to gain insight into how the model makes predictions. We trained ferrets to report a target word’s presence, timing, and lateralization within a stream of consecutively presented non-target words. To assess the animals’ ability to generalize across pitch, we manipulated the fundamental frequency (F0) of the speech stimuli across trials, and to assess the contribution of pitch to streaming, we roved the F0 from word token to token. We then implemented gradient-boosted regression and decision trees on the trial outcome and reaction time data to understand the behavioral factors behind the ferrets’ decision-making. We visualized model contributions by implementing SHAPs feature importance and partial dependency plots. While ferrets could accurately perform the task across all pitch-shifted conditions, our models reveal subtle effects of shifting F0 on performance, with within-trial pitch shifting elevating false alarms and extending reaction times. Our models identified a subset of non-target words that animals commonly false alarmed to. Follow-up analysis demonstrated that the spectrotemporal similarity of target and non-target words rather than similarity in duration or amplitude waveform was the strongest predictor of the likelihood of false alarming. Finally, we compared the results with those obtained with traditional mixed effects models, revealing equivalent or better performance for the gradient-boosted models over these approaches.
Journal Article
The Level of the Transcription Factor Pax6 Is Essential for Controlling the Balance between Neural Stem Cell Self-Renewal and Neurogenesis
Neural stem cell self-renewal, neurogenesis, and cell fate determination are processes that control the generation of specific classes of neurons at the correct place and time. The transcription factor Pax6 is essential for neural stem cell proliferation, multipotency, and neurogenesis in many regions of the central nervous system, including the cerebral cortex. We used Pax6 as an entry point to define the cellular networks controlling neural stem cell self-renewal and neurogenesis in stem cells of the developing mouse cerebral cortex. We identified the genomic binding locations of Pax6 in neocortical stem cells during normal development and ascertained the functional significance of genes that we found to be regulated by Pax6, finding that Pax6 positively and directly regulates cohorts of genes that promote neural stem cell self-renewal, basal progenitor cell genesis, and neurogenesis. Notably, we defined a core network regulating neocortical stem cell decision-making in which Pax6 interacts with three other regulators of neurogenesis, Neurog2, Ascl1, and Hes1. Analyses of the biological function of Pax6 in neural stem cells through phenotypic analyses of Pax6 gain- and loss-of-function mutant cortices demonstrated that the Pax6-regulated networks operating in neural stem cells are highly dosage sensitive. Increasing Pax6 levels drives the system towards neurogenesis and basal progenitor cell genesis by increasing expression of a cohort of basal progenitor cell determinants, including the key transcription factor Eomes/Tbr2, and thus towards neurogenesis at the expense of self-renewal. Removing Pax6 reduces cortical stem cell self-renewal by decreasing expression of key cell cycle regulators, resulting in excess early neurogenesis. We find that the relative levels of Pax6, Hes1, and Neurog2 are key determinants of a dynamic network that controls whether neural stem cells self-renew, generate cortical neurons, or generate basal progenitor cells, a mechanism that has marked parallels with the transcriptional control of embryonic stem cell self-renewal.
Journal Article
The protective effect of inflammatory monocytes during systemic C. albicans infection is dependent on collaboration between C-type lectin-like receptors
Invasive candidiasis, mainly caused by Candida albicans, is a serious healthcare problem with high mortality rates, particularly in immunocompromised patients. Innate immune cells express pathogen recognition receptors (PRRs) including C-type lectin-like receptors (CLRs) that bind C. albicans to initiate an immune response. Multiple CLRs including Dectin-1, Dectin-2 and Mincle have been proposed individually to contribute to the immune response to C. albicans. However how these receptors collaborate to clear a fungal infection is unknown. Herein, we used novel multi-CLR knockout (KO) mice to decipher the individual, collaborative and collective roles of Dectin-1, Dectin-2 and Mincle during systemic C. albicans infection. These studies revealed an unappreciated and profound role for CLR co-operation in anti-fungal immunity. The protective effect of multiple CLRs was markedly greater than any single receptor, and was mediated through inflammatory monocytes via recognition and phagocytosis of C. albicans, and production of C. albicans-induced cytokines and chemokines. These CLRs were dispensable for mediating similar responses from neutrophils, likely due to lower expression of these CLRs on neutrophils compared to inflammatory monocytes. Concurrent deletion of Dectin-1 and Dectin-2, or all three CLRs, resulted in dramatically increased susceptibility to systemic C. albicans infection compared to mice lacking a single CLR. Multi-CLR KO mice were unable to control fungal growth due to an inadequate early inflammatory monocyte-mediated response. In response to excessive fungal growth, the multi-CLR KO mice mounted a hyper-inflammatory response, likely leading to multiple organ failure. Thus, these data reveal a critical role for CLR co-operation in the effective control of C. albicans and maintenance of organ function during infection.
Journal Article
Analysis of vocal communication in the genus Falco
Vocal learning occurs in three clades of birds: hummingbirds, parrots, and songbirds. Examining vocal communication within the Falconiformes (sister taxon to the parrot/songbird clade) may offer information in understanding the evolution of vocal learning. Falcons are considered non-vocal learners and variation in vocalization may only be the result of variation in anatomical structure, with size as the major factor. We measured syringes in seven
Falco
species in the collection at the American Museum of Natural History and compiled data on weight, wing length, and tail length. Audio recordings were downloaded from several libraries and the peak frequency and frequency slope per harmonic number, number of notes in each syllable, number of notes per second, duration of each note, and inter-note duration was measured. Mass, wing length, and syringeal measurements were strongly, positively correlated, and maximum frequency is strongly, negatively correlated with the size. Frequency slope also correlates with size, although not as strongly. Both note and inter-note length vary significantly among the seven species, and this variation is not correlated with size. Maximum frequency and frequency slope can be used to identify species, with the possibility that bird sounds could be used to identify species in the field in real time.
Journal Article
Policy mixes for more sustainable smart home technologies
Smart home technologies refer to devices that provide some degree of digitally connected, automated, or enhanced services to household occupants. Smart homes have become prominent in recent technology and policy discussions about energy efficiency, climate change, and the sustainability of buildings. Nevertheless, do they truly promote sustainability goals? Based on an extensive original dataset involving expert interviews, supplemented with a review of the literature, this study elaborates on an array of social, technical, political, and environmental risks facing smart home innovation, with clear implications for research, policy, and technology development. Only with a more thoughtful and coordinated mix of policies in place will smart home adoption begin to fulfill some of the sustainability objectives their advocates continually promise.
Journal Article
Marisa Mori and the Futurists
This book introduces a compelling new personality to the modernist canon, Marisa Mori (1900-1985), who became the only female contributor to The Futurist Cookbook (1932) with her recipe for “Italian Breasts in the Sun.” Offering something more complex than a traditional biographical account, Jennifer S. Griffiths charts Mori’s studies with Felice Casorati, her meeting with the Futurists in 1931, and her complex engagement with Magic Realist and Futurist themes throughout the 1930s. She provides a feminist critique of the art, converging on issues of gender, culture, and history to offer new critical perspectives on Italian modernism. Contributing to a growing body of knowledge on the women who participated in the Italian Futurist movement, this book highlights Mori’s artistic contributions before, during, and after her Futurist decade. It also details her fascination with the expressive potential of the female nude, analyses how her work evidences an early interest in the politics of the body, and situates her most significant artworks in their critical context looking through the historical, political, and cultural framework of interwar Fascism. Mori worked outside the major European capitals, fluctuated between traditional figurative subjects and abstract experimentation, and occupied a marginal place in a history that privileges the masculine, the urban, and the abstract; thus her art can help to re-think and re-situate the margins of modernism. It explores a woman artist’s struggle for modernity among the Italian Futurists in an age of Fascism.
eBook
Resource-dependent biodiversity and potential multi-trophic interactions determine belowground functional trait stability
Background
For achieving long-term sustainability of intensive agricultural practices, it is pivotal to understand belowground functional stability as belowground organisms play essential roles in soil biogeochemical cycling. It is commonly believed that resource availability is critical for controlling the soil biodiversity and belowground organism interactions that ultimately lead to the stabilization or collapse of terrestrial ecosystem functions, but evidence to support this belief is still limited. Here, we leveraged field experiments from the Chinese National Ecosystem Research Network (CERN) and two microcosm experiments mimicking high and low resource conditions to explore how resource availability mediates soil biodiversity and potential multi-trophic interactions to control functional trait stability.
Results
We found that agricultural practice-induced higher resource availability increased potential cross-trophic interactions over 316% in fields, which in turn had a greater effect on functional trait stability, while low resource availability made the stability more dependent on the potential within trophic interactions and soil biodiversity. This large-scale pattern was confirmed by fine-scale microcosm systems, showing that microcosms with sufficient nutrient supply increase the proportion of potential cross-trophic interactions, which were positively associated with functional stability. Resource-driven belowground biodiversity and multi-trophic interactions ultimately feedback to the stability of plant biomass.
Conclusions
Our results indicated the importance of potential multi-trophic interactions in supporting belowground functional trait stability, especially when nutrients are sufficient, and also suggested the ecological benefits of fertilization programs in modern agricultural intensification.
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Video Abstract
Journal Article