Unique Functional Roles Research Articles

Extinctions of Threatened Frogs may Impact Ecosystems in a Global Hotspot of Anuran Diversity

Human activity is accelerating rates of extinction around the world, and there is therefore an urgent need to understand the potential consequences of species loss on functional diversity and ecosystem functioning. It is frequently assumed that the extinction of threatened species, which are usually rare species, may have limited effects on ecosystem functioning, especially within highly diverse regions, given the low abundance of individuals of each species and the potentially high functional redundancy among them. However, these rare species may contribute unique and irreplaceable functional roles, and therefore their extinction could have disproportionate impacts on ecosystems. We assess the functional importance of highly threatened anurans (frogs and toads) and then explore how the loss of these threatened species would impact spatial patterns of β-diversity in Ecuador, a hotspot of anuran biodiversity and endemism. We found that highly threatened species are, on average, more functionally distinct at an assemblage level than are less threatened anurans. We then show that the potential extinction of these highly endangered species would drive the taxonomic, phylogenetic, and, especially, functional homogenization of anuran assemblages across the Ecuadorian Andes. We suggest this could lead to profound alterations in the stability of local ecosystem functioning. Finally, we highlight the limited scope of the existing network of protected areas in Ecuador to effectively cover anuran assemblages predicted to become increasingly functionally homogenous. Our study underscores the potential losses of functional diversity that accompany species extinctions and the importance of considering the many facets of biodiversity in conservation decision-making.

A lower affinity to cytosolic proteins reveals VDAC3 isoform-specific role in mitochondrial biology.

Voltage-dependent anion channel (VDAC) is the major pathway for the transport of ions and metabolites across the mitochondrial outer membrane. Among the three known mammalian VDAC isoforms, VDAC3 is the least characterized, but unique functional roles have been proposed in cellular and animal models. Yet, a high-sequence similarity between VDAC1 and VDAC3 is indicative of a similar pore-forming structure. Here, we conclusively show that VDAC3 forms stable, highly conductive voltage-gated channels that, much like VDAC1, are weakly anion selective and facilitate metabolite exchange, but exhibit unique properties when interacting with the cytosolic proteins α-synuclein and tubulin. These two proteins are known to be potent regulators of VDAC1 and induce similar characteristic blockages (on the millisecond time scale) of VDAC3, but with 10- to 100-fold reduced on-rates and altered α-synuclein blocking times, indicative of an isoform-specific function. Through cysteine scanning mutagenesis, we found that VDAC3's cysteine residues regulate its interaction with α-synuclein, demonstrating VDAC3-unique functional properties and further highlighting a general molecular mechanism for VDAC isoform-specific regulation of mitochondrial bioenergetics.

Multiple mitochondrial thioesterases have distinct tissue and substrate specificity and CoA regulation, suggesting unique functional roles

Acyl-CoA thioesterases (Acots) hydrolyze fatty acyl-CoA esters. Acots in the mitochondrial matrix are poised to mitigate β-oxidation overload and maintain CoA availability. Several Acots associate with mitochondria, but whether they all localize to the matrix, are redundant, or have different roles is unresolved. Here, we compared the suborganellar localization, activity, expression, and regulation among mitochondrial Acots (Acot2, -7, -9, and -13) in mitochondria from multiple mouse tissues and from a model of Acot2 depletion. Acot7, -9, and -13 localized to the matrix, joining Acot2 that was previously shown to localize there. Mitochondria from heart, skeletal muscle, brown adipose tissue, and kidney robustly expressed Acot2, -9, and -13; Acot9 levels were substantially higher in brown adipose tissue and kidney mitochondria, as was activity for C4:0-CoA, a unique Acot9 substrate. In all tissues, Acot2 accounted for about half of the thioesterase activity for C14:0-CoA and C16:0-CoA. In contrast, liver mitochondria from fed and fasted mice expressed little Acot activity, which was confined to long-chain CoAs and due mainly to Acot7 and Acot13 activities. Matrix Acots occupied different functional niches, based on substrate specificity (Acot9 versus Acot2 and -13) and strong CoA inhibition (Acot7, -9, and -13, but not Acot2). Interpreted in the context of β-oxidation, CoA inhibition would prevent Acot-mediated suppression of β-oxidation, while providing a release valve when CoA is limiting. In contrast, CoA-insensitive Acot2 could provide a constitutive siphon for long-chain fatty acyl-CoAs. These results reveal how the family of matrix Acots can mitigate β-oxidation overload and prevent CoA limitation.

Pan-specific and partially selective dye-labeled peptidic inhibitors of the polycomb paralog proteins

Epigenetic regulation of gene expression is in part controlled by post-translational modifications on histone proteins. Histone methylation is a key epigenetic mark that controls gene transcription and repression. There are five human polycomb paralog proteins (Cbx2/4/6/7/8) that use their chromodomains to recognize trimethylated lysine 27 on histone 3 (H3K27me3). Recognition of the methyllysine side chain is achieved through multiple cation-pi interactions within an ‘aromatic cage’ motif. Despite high structural similarity within the chromodomains of this protein family, they each have unique functional roles and are linked to different cancers. Selective inhibition of different CBX proteins is desirable for both fundamental studies and potential therapeutic applications. We report here on a series of peptidic inhibitors that target certain polycomb paralogs. We have identified peptidic scaffolds with sub-micromolar potency, and will report examples that are pan-specific and that are partially selective for individual members within the family. These results highlight important structure-activity relationships that allow for differential binding to be achieved through interactions outside of the methyllysine-binding aromatic cage motif.

Thymically-derived Foxp3+ regulatory T cells are the primary regulators of type 1 diabetes in the non-obese diabetic mouse model.

Regulatory T cells (Tregs) are an immunosuppressive population that are identified based on the stable expression of the fate-determining transcription factor forkhead box P3 (Foxp3). Tregs can be divided into distinct subsets based on whether they developed in the thymus (tTregs) or in the periphery (pTregs). Whether there are unique functional roles that distinguish pTregs and tTregs remains largely unclear. To elucidate these functions, efforts have been made to specifically identify and modify individual Treg subsets. Deletion of the conserved non-coding sequence (CNS)1 in the Foxp3 locus leads to selective impairment of pTreg generation without disrupting tTreg generation in the C57BL/6J background. Using CRISPR-Cas9 genome editing technology, we removed the Foxp3 CNS1 region in the non-obese diabetic (NOD) mouse model of spontaneous type 1 diabetes mellitus (T1D) to determine if pTregs contribute to autoimmune regulation. Deletion of CNS1 impaired in vitro induction of Foxp3 in naïve NOD CD4+ T cells, but it did not alter Tregs in most lymphoid and non-lymphoid tissues analyzed except for the large intestine lamina propria, where a small but significant decrease in RORγt+ Tregs and corresponding increase in Helios+ Tregs was observed in NOD CNS1-/- mice. CNS1 deletion also did not alter the development of T1D or glucose tolerance despite increased pancreatic insulitis in pre-diabetic female NOD CNS1-/- mice. Furthermore, the proportions of autoreactive Tregs and conventional T cells (Tconvs) within pancreatic islets were unchanged. These results suggest that pTregs dependent on the Foxp3 CNS1 region are not the dominant regulatory population controlling T1D in the NOD mouse model.

Neocortical Cell Classes: Essential Contributions fromElectrophysiology.

Neocortical cells form classes that likely take on unique functional roles in the cortical microcircuit. A new study finds that, with sufficient sampling, the electrophysiological signature of cells distinguishes four cell classes across primate frontal and parietal cortex.

Interrogating Indus inscriptions to unravel their mechanisms of meaning conveyance

This study conducts an epigraphic analysis of the yet undeciphered inscriptions of the ancient Indus Valley civilization and seeks to prove that just like proto-cuneiform administrative tablets of ancient Mesopotamia, or modern fiscal stamps and ration tokens, Indus seals and tablets too were formalized data-carriers that used both document-specific and linguistic syntaxes to convey messages. Analyzing various combinatorial patterns of Indus signs (e.g., typical co-occurrence restrictions present between some signs; tendency of some signs to form collocations; syntactic order(s) maintained between certain signs; strong positional preferences demonstrated by some signs; and the capability of certain signs to occur alone in inscriptions), this paper argues that Indus signs represented different content-morphemes and functional-morphemes—not phonograms used for spelling words—the majority of the inscriptions were logographic. Categorizing several Indus logograms into nine functional classes, it explores the way each sign-class has played unique functional roles for conveying complete messages through the brief inscriptions. By glossing the signs of the inscriptions using the names of their respective functional classes the study unravels the formulaic phrase-structures maintained by the majority of the inscriptions, where signs identified as phrase-final signs typically occur at the terminal positions of the semantic phrases, while signs used as connective-morphemes join semantically autonomous constituents in certain subordinating and coordinating ways, to form longer composite inscriptions. The study identifies certain Indus signs as numerical and metrological signs, which frequently collocate with specific lexemes, and clearly quantifying them in certain ways. This article also analyses the underlying relationships between certain metrological and phrase-final signs; examines the compositional nature of Indus collocations; and argues that some of the repeated sign-sequences were probable examples of linguistic reduplication. Analyzing the occasional occurrences of certain attributive quantifier signs as substantive lexemes, this paper suggests that in some inscriptional contexts those quantifier signs possibly represented certain commonly used metonyms of Indus civilization. Finally, this study explores the compositional semantics of Indus inscriptions without assigning any sound value to the signs and without speculating about whether the script encoded the speech of any specific ancient language.

RNA regulons are essential in intestinal homeostasis.

Intestinal epithelial cells are among the most rapidly proliferating cell types in the human body. There are several different subtypes of epithelial cells, each with unique functional roles in responding to the ever-changing environment. The epithelium's ability for rapid and customized responses to environmental changes requires multitiered levels of gene regulation. An emerging paradigm in gastrointestinal epithelial cells is the regulation of functionally related mRNA families, or regulons, via RNA-binding proteins (RBPs). RBPs represent a rapid and efficient mechanism to regulate gene expression and cell function. In this review, we will provide an overview of intestinal epithelial RBPs and how they contribute specifically to intestinal epithelial stem cell dynamics. In addition, we will highlight key gaps in knowledge in the global understanding of RBPs in gastrointestinal physiology as an opportunity for future studies.

Phylogenetic and CRISPR/Cas9 Studies in Deciphering the Evolutionary Trajectory and Phenotypic Impacts of Rice ERECTA Genes.

The ERECTA family genes (ERfs) have been found to play diverse functions in Arabidopsis, including controlling cell proliferation and cell growth, regulating stomata patterning, and responding to various stresses. This wide range of functions has rendered them as a potential candidate for crop improvement. However, information on their functional roles, particularly their morphological impact, in crop genomes, such as rice, is limited. Here, through evolutionary prediction, we first depict the evolutionary trajectory of the ER family, and show that the ER family is actually highly conserved across different species, suggesting that most of their functions may also be observed in other plant species. We then take advantage of the CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats–associated nuclease 9) system to assess their morphological impact on one of the most important crops, rice. Loss-of-function mutants of OsER1 and OsER2 display shortened plant stature and reduced panicle size, suggesting they possibly also functioned in regulating cell proliferation and cell growth in rice. In addition to functions similar to that in Arabidopsis, we also find clues that rice ERfs may play unique functional roles. The OsER2 displayed more severe phenotypic changes than OsER1, indicating putative differentiation in their functions. The OsERL might be of essential in its function, and the proper function of all three rice ER genes might be dependent of their genetic background. Future investigations relating to these functions are key to exploiting ERfs in crop development.

Demonstration of the potential of environmental DNA as a tool for the detection of avian species

Birds play unique functional roles in the maintenance of ecosystems, such as pollination and seed dispersal, and thus monitoring bird species diversity is a first step towards avoiding undesirable consequences of anthropogenic impacts on bird communities. In the present study, we hypothesized that birds, regardless of their main habitats, must have frequent contact with water and that tissues that contain their DNA that persists in the environment (environmental DNA; eDNA) could be used to detect the presence of avian species. To this end, we applied a set of universal PCR primers (MiBird, a modified version of fish/mammal universal primers) for metabarcoding avian eDNA. We confirmed the versatility of MiBird primers by performing in silico analyses and by amplifying DNAs extracted from bird tissues. Analyses of water samples from zoo cages of birds with known species composition suggested that the use of MiBird primers combined with Illumina MiSeq could successfully detect avian species from water samples. Additionally, analysis of water samples collected from a natural pond detected five avian species common to the sampling areas. The present findings suggest that avian eDNA metabarcoding would be a complementary detection/identification tool in cases where visual census of bird species is difficult.

Keratan sulfate, a complex glycosaminoglycan with unique functional capability.

From an evolutionary perspective keratan sulfate (KS) is the newest glycosaminoglycan (GAG) but the least understood. KS is a sophisticated molecule with a diverse structure, and unique functional roles continue to be uncovered for this GAG. The cornea is the richest tissue source of KS in the human body but the central and peripheral nervous systems also contain significant levels of KS and a diverse range of KS-proteoglycans with essential functional roles. KS also displays important cell regulatory properties in epithelial and mesenchymal tissues and in bone and in tumor development of diagnostic and prognostic utility. Corneal KS-I displays variable degrees of sulfation along the KS chain ranging from non-sulfated polylactosamine, mono-sulfated and disulfated disaccharide regions. Skeletal KS-II is almost completely sulfated consisting of disulfated disaccharides interrupted by occasional mono-sulfated N-acetyllactosamine residues. KS-III also contains highly sulfated KS disaccharides but differs from KS-I and KS-II through 2-O-mannose linkage to serine or threonine core protein residues on proteoglycans such as phosphacan and abakan in brain tissue. Historically, the major emphasis on the biology of KS has focused on its sulfated regions for good reason. The sulfation motifs on KS convey important molecular recognition information and direct cell behavior through a number of interactive proteins. Emerging evidence also suggest functional roles for the poly-N-acetyllactosamine regions of KS requiring further investigation. Thus further research is warranted to better understand the complexities of KS.

Interrogating Indus Inscriptions Through Their Context, Structure and Compositional Semantics, to Understand Their Inner Logic of Message Conveyance

This study conducts an epigraphic analysis of the yet undeciphered inscriptions of the ancient Indus Valley civilization and seeks to prove that just like proto-cuneiform administrative tablets of ancient Mesopotamia, or modern fiscal stamps and ration tokens, Indus seals and tablets too were formalized data-carriers that used both document-specific and linguistic syntaxes to convey messages. Analyzing various combinatorial patterns of Indus signs (e.g., typical co-occurrence restrictions present between some signs; tendency of some signs to form collocations; syntactic order(s) maintained between certain signs; strong positional preferences demonstrated by some signs; and the capability of certain signs to occur alone in inscriptions), this paper argues that Indus signs represented different content-morphemes and functional-morphemes — not phonograms used for spelling words — the majority of the inscriptions were logographic. Categorizing several Indus logograms into nine functional classes, it explores the way each sign-class has played unique functional roles for conveying complete messages through the brief inscriptions. By glossing the signs of the inscriptions using the names of their respective functional classes the study unravels the formulaic phrase-structures maintained by the majority of the inscriptions, where signs identified as phrase-final signs typically occur at the terminal positions of the semantic phrases, while signs used as connective-morphemes join semantically autonomous constituents in certain subordinating and coordinating ways, to form longer composite inscriptions. The study identifies certain Indus signs as numerical and metrological signs, which frequently collocate with specific lexemes, and clearly quantifying them in certain ways. This article also analyses the underlying relationships between certain metrological and phrase-final signs; examines the compositional nature of Indus collocations; and argues that some of the repeated sign-sequences were probable examples of linguistic reduplication. Analyzing the occasional occurrences of certain attributive quantifier signs as substantive lexemes, this paper suggests that in some inscriptional contexts those quantifier signs possibly represented certain commonly used metonyms of Indus civilization. Finally, this study explores the compositional semantics of Indus inscriptions without assigning any sound value to the signs and without speculating about whether the script encoded the speech of any specific ancient language.

Extracellular matrix directs phenotypic heterogeneity of activated fibroblasts

Activated fibroblasts are key players in the injury response, tumorigenesis, fibrosis, and inflammation. Dichotomous outcomes in response to varied stroma-targeted therapies in cancer emphasize the need to disentangle the roles of heterogeneous fibroblast subsets in physiological and pathophysiological settings. In wound healing, fibrosis, and myriad tumor types, fibroblast activation protein (FAP) and alpha-smooth muscle actin (αSMA) identify distinct, yet overlapping, activated fibroblast subsets. Prior studies established that FAPHi reactive fibroblasts and αSMAHi myofibroblasts can exert opposing influences in tumorigenesis. However, the factors that drive this phenotypic heterogeneity and the unique functional roles of these subsets have not been defined. We demonstrate that a convergence of ECM composition, elasticity, and transforming growth factor beta (TGF-β) signaling governs activated fibroblast phenotypic heterogeneity. Furthermore, FAPHi reactive fibroblasts and αSMAHi myofibroblasts exhibited distinct gene expression signatures and functionality in vitro, illuminating potentially unique roles of activated fibroblast subsets in tissue remodeling. These insights into activated fibroblast heterogeneity will inform the rational design of stroma-targeted therapies for cancer and fibrosis.

Nitric Oxide-Dependent Feedback Loop Regulates Transient Receptor Potential Vanilloid 4 (TRPV4) Channel Cooperativity and Endothelial Function in Small Pulmonary Arteries.

BackgroundRecent studies demonstrate that spatially restricted, local Ca2+ signals are key regulators of endothelium‐dependent vasodilation in systemic circulation. There are drastic functional differences between pulmonary arteries (PAs) and systemic arteries, but the local Ca2+ signals that control endothelium‐dependent vasodilation of PAs are not known. Localized, unitary Ca2+ influx events through transient receptor potential vanilloid 4 (TRPV4) channels, termed TRPV4 sparklets, regulate endothelium‐dependent vasodilation in resistance‐sized mesenteric arteries via activation of Ca2+‐dependent K+ channels. The objective of this study was to determine the unique functional roles, signaling targets, and endogenous regulators of TRPV4 sparklets in resistance‐sized PAs.Methods and ResultsUsing confocal imaging, custom image analysis, and pressure myography in fourth‐order PAs in conjunction with knockout mouse models, we report a novel Ca2+ signaling mechanism that regulates endothelium‐dependent vasodilation in resistance‐sized PAs. TRPV4 sparklets exhibit distinct spatial localization in PAs when compared with mesenteric arteries, and preferentially activate endothelial nitric oxide synthase (eNOS). Nitric oxide released by TRPV4‐endothelial nitric oxide synthase signaling not only promotes vasodilation, but also initiates a guanylyl cyclase‐protein kinase G‐dependent negative feedback loop that inhibits cooperative openings of TRPV4 channels, thus limiting sparklet activity. Moreover, we discovered that adenosine triphosphate dilates PAs through a P2 purinergic receptor‐dependent activation of TRPV4 sparklets.ConclusionsOur results reveal a spatially distinct TRPV4‐endothelial nitric oxide synthase signaling mechanism and its novel endogenous regulators in resistance‐sized PAs.

Lipidomics of equine amniotic fluid: Identification of amphiphilic (O-acyl)-ω-hydroxy-fatty acids

Amniotic fluid is essential for the growth and maturation of the fetus prior to parturition. While our knowledge of human amniotic fluid is extensive, current data for equine amniotic fluid is limited. We therefore undertook a detailed lipidomics analysis of equine amniotic fluid. Using a non-targeted high-resolution mass spectrometric lipidomics analysis of equine amniotic fluid, we were able to characterize a diverse array of individual lipids. This non-biased analytical approach detected, for the first time, the presence of (O-acyl)-ω-hydroxy-fatty acids (OAHFA) with up to 52 carbon chain lengths in amniotic fluid. The identities of these lipid amphiphiles were validated both by high-resolution mass spectrometry and by tandem mass spectrometry (<2 ppm mass error) which identified the fatty acid and hydroxy-fatty acid components of individual OAHFAs. The only previous identification of OAHFAs has been in sperm and meibomian glands, and their sebaceous secretions, suggesting that these lipids may have unique functional roles in highly specialized compartments. The amphiphilic and surfactant properties of these unique lipids could provide an interface between amniotic lipids and fetal skin and/or lungs. The potential roles of OAHFAs as well as their source in amniotic fluid remain to be explored based upon these novel lipidomics findings but our study of the developmental time course of amniotic OAHFAs suggest that they may act as lubricants in delivery and/or a role in the development of fetal lung function around parturition.

Analyses of PDE-regulated phosphoproteomes reveal unique and specific cAMP-signaling modules in T cells

Specific functions for different cyclic nucleotide phosphodiesterases (PDEs) have not yet been identified in most cell types. Conventional approaches to study PDE function typically rely on measurements of global cAMP, general increases in cAMP-dependent protein kinase (PKA), or the activity of exchange protein activated by cAMP (EPAC). Although newer approaches using subcellularly targeted FRET reporter sensors have helped define more compartmentalized regulation of cAMP, PKA, and EPAC, they have limited ability to link this regulation to downstream effector molecules and biological functions. To address this problem, we have begun to use an unbiased mass spectrometry-based approach coupled with treatment using PDE isozyme-selective inhibitors to characterize the phosphoproteomes of the functional pools of cAMP/PKA/EPAC that are regulated by specific cAMP-PDEs (the PDE-regulated phosphoproteomes). In Jurkat cells we find multiple, distinct PDE-regulated phosphoproteomes that can be defined by their responses to different PDE inhibitors. We also find that little phosphorylation occurs unless at least two different PDEs are concurrently inhibited in these cells. Moreover, bioinformatics analyses of these phosphoproteomes provide insight into the unique functional roles, mechanisms of action, and synergistic relationships among the different PDEs that coordinate cAMP-signaling cascades in these cells. The data strongly suggest that the phosphorylation of many different substrates contributes to cAMP-dependent regulation of these cells. The findings further suggest that the approach of using selective, inhibitor-dependent phosphoproteome analysis can provide a generalized methodology for understanding the roles of different PDEs in the regulation of cyclic nucleotide signaling.

Transposable elements in Drosophila.

ABSTRACTTransposable elements (TEs) are mobile genetic elements that can mobilize within host genomes. As TEs comprise more than 40% of the human genome and are linked to numerous diseases, understanding their mechanisms of mobilization and regulation is important. Drosophila melanogaster is an ideal model organism for the study of eukaryotic TEs as its genome contains a diverse array of active TEs. TEs universally impact host genome size via transposition and deletion events, but may also adopt unique functional roles in host organisms. There are 2 main classes of TEs: DNA transposons and retrotransposons. These classes are further divided into subgroups of TEs with unique structural and functional characteristics, demonstrating the significant variability among these elements. Despite this variability, D. melanogaster and other eukaryotic organisms utilize conserved mechanisms to regulate TEs. This review focuses on the transposition mechanisms and regulatory pathways of TEs, and their functional roles in D. melanogaster.

The role of RNA uptake in platelet heterogeneity.

The role of platelets in regulating vascular homeostasis has expanded beyond mediation of haemostasis and thrombosis. The discovery of platelet RNA and the presence of subpopulations of platelets containing varying amounts of RNA suggest a role for platelet transcripts in vascular function. As the RNA in anucleated platelets is biologically functional and may transfer to other vascular cells, we hypothesised that platelet RNA diminishes over the lifespan of the platelet with diminishing platelet size due to horizontal cellular transfer. The purpose of this study is to determine if platelet RNA variance is the result of horizontal cellular transfer between platelets and other vascular cells. Utilising platelet sorting and RNA sequencing, we found that smaller platelets contained a more diverse set of transcripts than larger platelets. Further investigation using fluorescence imaging, gene expression analyses and in vitro and in vivo modelling revealed that platelets take up RNA from other vascular cells in a complex manner, revealing a dynamic role for platelets in modulating vascular homeostasis through bidirectional RNA transfer. The resultant RNA profile heterogeneity suggests unique functional roles for platelets dependent on size and complexity. This study expands our basic understanding of platelet function and heterogeneity and is the first to evaluate endogenous vascular RNA uptake and its relation to platelet processes. Our findings describe a novel endogenous phenomenon that can help elucidate the platelet's role in these non-thrombotic and haemostatic fields, as well as present potential for diagnostic and therapeutic development.

Differential Inputs to the Perisomatic and Distal-Dendritic Compartments of VIP-Positive Neurons in Layer 2/3 of the Mouse Barrel Cortex.

The recurrent network composed of excitatory and inhibitory neurons is fundamental to neocortical function. Inhibitory neurons in the mammalian neocortex are molecularly diverse, and individual cell types play unique functional roles in the neocortical microcircuit. Recently, vasoactive intestinal polypeptide-positive (VIP+) neurons, comprising a subclass of inhibitory neurons, have attracted particular attention because they can disinhibit pyramidal cells through inhibition of other types of inhibitory neurons, such as parvalbumin- (PV+) and somatostatin-positive (SOM+) inhibitory neurons, promoting sensory information processing. Although VIP+ neurons have been reported to receive synaptic inputs from PV+ and SOM+ inhibitory neurons as well as from cortical and thalamic excitatory neurons, the somatodendritic localization of these synaptic inputs has yet to be elucidated at subcellular spatial resolution. In the present study, we visualized the somatodendritic membranes of layer (L) 2/3 VIP+ neurons by injecting a newly developed adeno-associated virus (AAV) vector into the barrel cortex of VIP-Cre knock-in mice, and we determined the extensive ramification of VIP+ neuron dendrites in the vertical orientation. After immunohistochemical labeling of presynaptic boutons and postsynaptic structures, confocal laser scanning microscopy revealed that the synaptic contacts were unevenly distributed throughout the perisomatic (<100 μm from the somata) and distal-dendritic compartments (≥100 μm) of VIP+ neurons. Both corticocortical and thalamocortical excitatory neurons preferentially targeted the distal-dendritic compartment of VIP+ neurons. On the other hand, SOM+ and PV+ inhibitory neurons preferentially targeted the distal-dendritic and perisomatic compartments of VIP+ neurons, respectively. Notably, VIP+ neurons had few reciprocal connections. These observations suggest different inhibitory effects of SOM+ and PV+ neuronal inputs on VIP+ neuron activity; inhibitory inputs from SOM+ neurons likely modulate excitatory inputs locally in dendrites, while PV+ neurons could efficiently interfere with action potential generation through innervation of the perisomatic domain of VIP+ neurons. The present study, which shows a precise configuration of site-specific inputs, provides a structural basis for the integration mechanism of synaptic inputs to VIP+ neurons.

Unexpected high vulnerability of functions in wilderness areas: evidence from coral reef fishes.

High species richness is thought to support the delivery of multiple ecosystem functions and services under changing environments. Yet, some species might perform unique functional roles while others are redundant. Thus, the benefits of high species richness in maintaining ecosystem functioning are uncertain if functions have little redundancy, potentially leading to high vulnerability of functions. We studied the natural propensity of assemblages to be functionally buffered against loss prior to fishing activities, using functional trait combinations, in coral reef fish assemblages across unfished wilderness areas of the Indo-Pacific: Chagos Archipelago, New Caledonia and French Polynesia. Fish functional diversity in these wilderness areas is highly vulnerable to fishing, explained by species- and abundance-based redundancy packed into a small combination of traits, leaving most other trait combinations (60%) sensitive to fishing, with no redundancy. Functional vulnerability peaks for mobile and sedentary top predators, and large species in general. Functional vulnerability decreases for certain functional entities in New Caledonia, where overall functional redundancy was higher. Uncovering these baseline patterns of functional vulnerability can offer early warning signals of the damaging effects from fishing, and may serve as baselines to guide precautionary and even proactive conservation actions.