Current Biology最新文献

The CRY2 photoreceptor is known to form homotetramers that bind to transcription regulators to affect gene expression in response to light. A new study provides evidence that the CRY2 monomer binds different transcription regulators to affect gene expression in darkness, suggesting that photoreceptors change activity in response to light.

Eukaryotic cells typically express multiple tubulin isoforms that form the microtubule cytoskeleton. A new study of the evolution and functional diversification of pools of tubulin isoforms suggests that these proteins are part of a co-evolving network that includes the extensive microtubule interactome.

There is increasing evidence that ecosystems are affected by multiple global change factors,^1,2,3 impeding the sustainability of multiple soil functions.⁴ Biodiversity can buffer ecosystem functions against environmental changes, a concept largely supported by insurance and portfolio theories.^5,6 However, the role of soil biodiversity, especially the diversity of abundant and rare microbial taxa, in regulating soil multifunctionality resistance under an increasing number of global change factors remains poorly explored. Here, we assessed the effects of the diversity of abundant and rare microbial taxa on soil multifunctionality resistance under different numbers of global change factors using 650 microcosms. The increasing number of global change factors reduced the effects of the diversity of abundant and rare microbial taxa on soil multifunctionality resistance and shifted their relative importance. The diversity of abundant taxa showed stronger positive effects on soil multifunctionality resistance under one or two global change factors. However, the diversity of rare taxa had stronger effects under multiple co-acting global change factors. The resistance of abundant and rare microbial taxa was significantly associated with their respective diversity effects on soil multifunctionality resistance. These effects were represented by standardized slopes that evaluated the relationships between microbial diversity and multifunctionality resistance under varying numbers of global change factors. Our findings indicate a shift in the relative importance of the diversity of abundant and rare microbial taxa in regulating soil multifunctionality resistance with an increasing number of global change factors, providing new insights into the relationship between soil biodiversity and ecosystem stability under environmental disturbances.

Humans and other animals learn the abstract structure of a task and then use this structure to rapidly generalize to new situations. A recent study reveals how the brain builds and uses abstract task representations.

The United States Endangered Species Act (ESA) of 1973 set a precedent for biodiversity conservation across the globe.¹ A key requirement of protections afforded by the ESA is the accurate delimitation of imperiled species. We present a comparative reference-based taxonomic approach to species delimitation that integrates genomic and morphological data for objectively assessing the distinctiveness of species targeted for protection by governmental agencies. We apply this protocol to the Snail Darter (Percina tanasi), a freshwater fish from the Tennessee River that was discovered in 1973 and declared an endangered species under the ESA in 1975.² Concurrently, the Snail Darter's habitat was slated to be destroyed through the construction of the Tellico Dam by the Tennessee Valley Authority (TVA),^3,4 inspiring nationwide protests advocating for the suspension of the federal project. This David versus Goliath struggle between supporters of the 3-inch fish and the TVA culminated in the first major legal conflict over protections afforded by the ESA, the US Supreme Court case Hill v. TVA, 437 U.S. 153 (1978), with a 6 to 3 ruling in favor of protecting the Snail Darter and interrupting the completion of the Tellico Dam. Here, we integrate multiple lines of evidence in a comparative framework to demonstrate that despite its legacy, the Snail Darter is not a distinct species but is a population of the Stargazing Darter (Percina uranidea) described in 1887. These results illustrate how a reference-based framework for species delimitation dramatically aids the proper direction of efforts toward protecting biodiversity.

Human and non-human primate studies clearly implicate the dorsolateral prefrontal cortex (dlPFC) as critical for advanced cognitive functions.^1,2 It is thought that intracortical synaptic architectures within the dlPFC are the integral neurobiological substrate that gives rise to these processes.^3,4,5,6,7 In the prevailing model, each cortical column makes up one fundamental processing unit composed of dense intrinsic connectivity, conceptualized as the "canonical" cortical microcircuit.^3,8 Each cortical microcircuit receives sensory and cognitive information from upstream sources, which are represented by sustained activity within the microcircuit, referred to as persistent or recurrent activity.^4,9 Via recurrent connections within the microcircuit, activity propagates for a variable length of time, thereby allowing temporary storage and computations to occur locally before ultimately passing a transformed representation to a downstream output.^4,5,10 Competing theories regarding how microcircuit activity is coordinated have proven difficult to reconcile in vivo, where intercortical and intracortical computations cannot be fully dissociated.^5,9,11,12 Here, using high-density calcium imaging of macaque dlPFC, we isolated intracortical computations by interrogating microcircuit networks ex vivo. Using peri-sulcal stimulation to evoke recurrent activity in deep layers, we found that activity propagates through stochastically assembled intracortical networks wherein orderly, predictable, low-dimensional collective dynamics arise from ensembles with highly labile cellular memberships. Microcircuit excitability covaried with individual cognitive performance, thus anchoring heuristic models of abstract cortical functions within quantifiable constraints imposed by the underlying synaptic architecture. Our findings argue against engram or localist architectures, together demonstrating that generation of high-fidelity population-level signals from distributed, labile networks is an intrinsic feature of dlPFC microcircuitry.

Social play in adults is considered rare in non-human species. A new study has found that play among adult chimpanzees is common and linked to cooperation and social bond maintenance. The societal function of adult social play may thus have deep evolutionary roots.

Integrative studies of diverse neuronal networks that govern social behavior are hindered by a lack of methods to record neural activity comprehensively across the entire brain. The recent development of the miniature fish Danionella cerebrum as a model organism offers one potential solution, as the small size and optical transparency of these animals make it possible to visualize circuit activity throughout the nervous system.^1,2,3,4 Here, we establish the feasibility of using Danionella as a model for social behavior and socially reinforced learning by showing that adult fish exhibit strong affiliative tendencies and that social interactions can serve as the reinforcer in an appetitive conditioning paradigm. Fish exhibited an acute ability to identify conspecifics and distinguish them from closely related species, which was mediated by both visual and particularly olfactory cues. These behaviors were abolished by pharmacological and genetic interference with oxytocin signaling, demonstrating the conservation of key neural mechanisms observed in other vertebrates.^{5,6,7,8,9,10,11} Our work validates Danionella as a tool for understanding the social brain in general and its modulation by neuropeptide signaling in particular.

A critical goal of vision is to detect changes in light intensity, even when these changes are blurred by the spatial resolution of the eye and the motion of the animal. Here, we describe a recurrent neural circuit in Drosophila that compensates for blur and thereby selectively enhances the perceived contrast of moving edges. Using in vivo, two-photon voltage imaging, we measured the temporal response properties of L1 and L2, two cell types that receive direct synaptic input from photoreceptors. These neurons have biphasic responses to brief flashes of light, a hallmark of cells that encode changes in stimulus intensity. However, the second phase was often much larger in area than the first, creating an unusual temporal filter. Genetic dissection revealed that recurrent neural circuitry strongly shapes the second phase of the response, informing the structure of a dynamical model. By applying this model to moving natural images, we demonstrate that rather than veridically representing stimulus changes, this temporal processing strategy systematically enhances them, amplifying and sharpening responses. Comparing the measured responses of L2 to model predictions across both artificial and natural stimuli revealed that L2 tunes its properties as the model predicts to temporally sharpen visual inputs. Since this strategy is tunable to behavioral context, generalizable to any time-varying sensory input, and implementable with a common circuit motif, we propose that it could be broadly used to selectively enhance sharp and salient changes.

Mechanical forces influence mitochondrial dynamics through previously unexplored mechanisms. A new study demonstrates that actomyosin tension inhibits mitochondrial fission by phosphorylating a key component of the fission complex and that this event regulates the nuclear accumulation of critical transcription factors.