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Aim:
Temperature, food resources and top‐down regulation by antagonists are considered as major drivers of insect diversity, but their relative importance is poorly understood. Here, we used cavity‐nesting communities of bees, wasps and their antagonists to reveal the role of temperature, food resources, parasitism rate and land use as drivers of species richness at different trophic levels along a broad elevational gradient.
Location:
Mt. Kilimanjaro, Tanzania.
Taxon:
Cavity‐nesting Hymenoptera (Hymenoptera: Apidae, Colletidae, Megachilidae, Crabronidae, Sphecidae, Pompilidae, Vespidae).
Methods:
We established trap nests on 25 study sites that were distributed over similar large distances in terms of elevation along an elevational gradient from 866 to 1788 m a.s.l., including both natural and disturbed habitats. We quantified species richness and abundance of bees, wasps and antagonists, parasitism rates and flower or arthropod food resources. Data were analysed with generalized linear models within a multi‐model inference framework.
Results:
Elevational species richness patterns changed with trophic level from monotonically declining richness of bees to increasingly humped‐shaped patterns for caterpillar‐hunting wasps, spider‐hunting wasps and antagonists. Parasitism rates generally declined with elevation but were higher for wasps than for bees. Temperature was the most important predictor of both bee and wasp host richness patterns. Antagonist richness patterns were also well predicted by temperature, but in contrast to host richness patterns, additionally by resource abundance and diversity. The conversion of natural habitats through anthropogenic land use, which included biomass removal, agricultural inputs, vegetation structure and percentage of surrounding agricultural habitats, had no significant effects on bee and wasp communities.
Main conclusions:
Our study underpins the importance of temperature as a main driver of diversity gradients in ectothermic organisms and reveals the increasingly important role of food resources at higher trophic levels. Higher parasitism rates at higher trophic levels and at higher temperatures indicated that the relative importance of bottom‐up and top‐down drivers of species richness change across trophic levels and may respond differently to future climate change.
Despite decades of scientific effort, there is still no consensus on the determinants of broad-scale gradients of animal diver-sity. We argue that general drivers of diversity are unlikely to be found among the narrowly defined taxa which are typically analyzed in studies of broad-scale diversity gradients because ecological niches evolve largely conservatively. This causes constraints in the use of available niche space leading to systematic differences in diversity gradients among taxa. We instead advocate studies of phylogenetically diverse animal communities along broad environmental gradients. Such multi-taxa communities are less constrained in resource use and diversification and may be better targets for testing major classical hypotheses on diversity gradients. Besides increasing the spatial scale in analyses, expanding the phylogenetic coverage may be a second way to achieve higher levels of generality in studies of broad-scale diversity gradients
Global sustainability agendas focus primarily on halting deforestation, yet the biodiversity crisis resulting from the degradation of remaining forests is going largely unnoticed. Forest degradation occurs through the loss of key ecological structures, such as dying trees and deadwood, even in the absence of deforestation. One of the main drivers of forest degradation is limited awareness by policy makers and the public on the importance of these structures for supporting forest biodiversity and ecosystem function. Here, we outline management strategies to protect forest health and biodiversity by maintaining and promoting deadwood, and propose environmental education initiatives to improve the general awareness of the importance of deadwood. Finally, we call for major reforms to forest management to maintain and restore deadwood; large, old trees; and other key ecological structures.
The transcription factor ∆Np63 is a master regulator of epithelial cell identity and essential for the survival of squamous cell carcinoma (SCC) of lung, head and neck, oesophagus, cervix and skin. Here, we report that the deubiquitylase USP28 stabilizes ∆Np63 and maintains elevated ∆NP63 levels in SCC by counteracting its proteasome‐mediated degradation. Impaired USP28 activity, either genetically or pharmacologically, abrogates the transcriptional identity and suppresses growth and survival of human SCC cells. CRISPR/Cas9‐engineered in vivo mouse models establish that endogenous USP28 is strictly required for both induction and maintenance of lung SCC. Our data strongly suggest that targeting ∆Np63 abundance via inhibition of USP28 is a promising strategy for the treatment of SCC tumours.
Mushroom bodies (MBs) are multisensory integration centers in the insect brain involved in learning and memory formation. In the honeybee, the main sensory input region (calyx) of MBs is comparatively large and receives input from mainly olfactory and visual senses, but also from gustatory/tactile modalities. Behavioral plasticity following differential brood care, changes in sensory exposure or the formation of associative long-term memory (LTM) was shown to be associated with structural plasticity in synaptic microcircuits (microglomeruli) within olfactory and visual compartments of the MB calyx. In the same line, physiological studies have demonstrated that MB-calyx microcircuits change response properties after associative learning. The aim of this review is to provide an update and synthesis of recent research on the plasticity of microcircuits in the MB calyx of the honeybee, specifically looking at the synaptic connectivity between sensory projection neurons (PNs) and MB intrinsic neurons (Kenyon cells). We focus on the honeybee as a favorable experimental insect for studying neuronal mechanisms underlying complex social behavior, but also compare it with other insect species for certain aspects. This review concludes by highlighting open questions and promising routes for future research aimed at understanding the causal relationships between neuronal and behavioral plasticity in this charismatic social insect.
Erfolgreiche räumliche Orientierung ist für viele Tiere eine alltägliche Herausforderung. Cataglyphis‐Wüstenameisen sind bekannt für ihre Navigationsfähigkeiten, mit deren Hilfe sie nach langen Futtersuchläufen problemlos zum Nest zurückfinden. Wie aber nehmen naive Ameisen ihre Navigationssysteme in Betrieb? Nach mehrwöchigem Innendienst im dunklen Nest werden sie zu Sammlerinnen bei hellem Sonnenschein. Dieser Wechsel erfordert einen drastischen Wandel im Verhalten sowie neuronale Veränderungen im Gehirn. Erfahrene Ameisen orientieren sich vor allem visuell, sie nutzen einen Himmelskompass und Landmarkenpanoramen. Daher absolvieren naive Ameisen stereotype Lernläufe, um ihren Kompass zu kalibrieren und die Nestumgebung kennenzulernen. Während der Lernläufe blicken sie wiederholt zum Nesteingang zurück und prägen sich so ihren Heimweg ein. Zur Ausrichtung ihrer Blicke nutzen sie das Erdmagnetfeld als Kompassreferenz. Cataglyphis‐Ameisen besitzen hierfür einen Magnetkompass, der bislang unbekannt war.
Amphibians evolved in the Devonian period about 400 Mya and represent a transition step in tetrapod evolution. Among amphibians, high-throughput sequencing data are very limited for Caudata, due to their largest genome sizes among terrestrial vertebrates. In this paper we present the transcriptome from the fire bellied newt Cynops orientalis. Data here presented display a high level of completeness, comparable to the fully sequenced genomes available from other amphibians. Moreover, this work focused on genes involved in gametogenesis and sexual development. Surprisingly, the gsdf gene was identified for the first time in a tetrapod species, so far known only from bony fish and basal sarcopterygians. Our analysis failed to isolate fgf24 and foxl3, supporting the possible loss of both genes in the common ancestor of Rhipidistians. In Cynops, the expression analysis of genes described to be sex-related in vertebrates singled out an expected functional role for some genes, while others displayed an unforeseen behavior, confirming the high variability of the sex-related pathway in vertebrates.
Preventing malnutrition through consuming nutritionally appropriate resources represents a challenge for foraging animals. This is due to often high variation in the nutritional quality of available resources. Foragers consequently need to evaluate different food sources. However, even the same food source can provide a plethora of nutritional and non‐nutritional cues, which could serve for quality assessment. We show that bumblebees, Bombus terrestris , overcome this challenge by relying on lipids as nutritional cue when selecting pollen. The bees ‘prioritised’ lipid perception in learning experiments and avoided lipid consumption in feeding experiments, which supported survival and reproduction. In contrast, survival and reproduction were severely reduced by increased lipid contents. Our study highlights the importance of fat regulation for pollen foraging bumblebees. It also reveals that nutrient perception, nutrient regulation and reproductive fitness can be linked, which represents an effective strategy enabling quick foraging decisions that prevent malnutrition and maximise fitness.
Salvage logging, or logging after natural disturbances such as wildfires, insect outbreaks, and windstorms, is carried out to recover some of a forest's natural and/or economic capital. However, trade‐offs between management objectives and a lack of consensus on the ecological consequences of salvage logging impair science‐based decision making on the management of forests after natural disturbances. We conducted a global meta‐analysis of the impacts of salvage logging on regulating ecosystem services and on fuel loads, as a frequent post‐disturbance objective is preventing subsequent wildfires that could be fueled by the accumulation of dead trunks and branches. Salvage logging affected ecosystem services in a moderately negative way, regardless of disturbance type and severity, time elapsed since salvage logging, intensity of salvage logging, and the group of regulating ecosystem services being considered. However, prolonging the time between natural disturbance and salvage logging mitigated negative effects on regulating ecosystem services. Salvage logging had no overall effect on surface fuels; rather, different fuel types responded differently depending on the time elapsed since salvage logging. Delaying salvage logging by ~2–4 years may reduce negative ecological impacts without affecting surface fuel loads.
Folliculin Controls the Intracellular Survival and Trans-Epithelial Passage of Neisseria gonorrhoeae
(2020)
Neisseria gonorrhoeae, a Gram-negative obligate human pathogenic bacterium, infects human epithelial cells and causes sexually transmitted diseases. Emerging multi-antibiotic resistant gonococci and increasing numbers of infections complicate the treatment of infected patients. Here, we used an shRNA library screen and next-generation sequencing to identify factors involved in epithelial cell infection. Folliculin (FLCN), a 64 kDa protein with a tumor repressor function was identified as a novel host factor important for N. gonorrhoeae survival after uptake. We further determined that FLCN did not affect N. gonorrhoeae adherence and invasion but was essential for its survival in the cells by modulating autophagy. In addition, FLCN was also required to maintain cell to cell contacts in the epithelial layer. In an infection model with polarized cells, FLCN inhibited the polarized localization of E-cadherin and the transcytosis of gonococci across polarized epithelial cells. In conclusion, we demonstrate here the connection between FLCN and bacterial infection and in particular the role of FLCN in the intracellular survival and transcytosis of gonococci across polarized epithelial cell layers.
Chlamydia trachomatis is the main cause of sexually transmitted diseases worldwide. As obligate intracellular bacteria Chlamydia replicate in a membrane bound vacuole called inclusion and acquire nutrients for growth and replication from their host cells. However, like all intracellular bacteria, Chlamydia have to prevent eradication by the host's cell autonomous system. The chlamydial deubiquitinase Cdu1 is secreted into the inclusion membrane, facing the host cell cytosol where it deubiquitinates cellular proteins. Here we show that inactivation of Cdu1 causes a growth defect of C. trachomatis in primary cells. Moreover, ubiquitin and several autophagy receptors are recruited to the inclusion membrane of Cdu1‐deficient Chlamydia . Interestingly, the growth defect of cdu1 mutants is not rescued when autophagy is prevented. We find reduced recruitment of Golgi vesicles to the inclusion of Cdu1 mutants indicating that vesicular trafficking is altered in bacteria without active deubiquitinase (DUB). Our work elucidates an important role of Cdu1 in the functional preservation of the chlamydial inclusion surface.
The predicted 80 open reading frames (ORFs) of herpes simplex virus 1 (HSV-1) have been intensively studied for decades. Here, we unravel the complete viral transcriptome and translatome during lytic infection with base-pair resolution by computational integration of multi-omics data. We identify a total of 201 transcripts and 284 ORFs including all known and 46 novel large ORFs. This includes a so far unknown ORF in the locus deleted in the FDA-approved oncolytic virus Imlygic. Multiple transcript isoforms expressed from individual gene loci explain translation of the vast majority of ORFs as well as N-terminal extensions (NTEs) and truncations. We show that NTEs with non-canonical start codons govern the subcellular protein localization and packaging of key viral regulators and structural proteins. We extend the current nomenclature to include all viral gene products and provide a genome browser that visualizes all the obtained data from whole genome to single-nucleotide resolution. Here, using computational integration of multi-omics data, the authors provide a detailed transcriptome and translatome of herpes simplex virus 1 (HSV-1), including previously unidentified ORFs and N-terminal extensions. The study also provides a HSV-1 genome browser and should be a valuable resource for further research.
Cataglyphis ants are known for their outstanding navigational abilities. They return to their inconspicuous nest after far‐reaching foraging trips using path integration, and whenever available, learn and memorize visual features of panoramic sceneries. To achieve this, the ants combine directional visual information from celestial cues and panoramic scenes with distance information from an intrinsic odometer. The largely vision‐based navigation in Cataglyphis requires sophisticated neuronal networks to process the broad repertoire of visual stimuli. Although Cataglyphis ants have been subjected to many neuroethological studies, little is known about the general neuronal organization of their central brain and the visual pathways beyond major circuits. Here, we provide a comprehensive, three‐dimensional neuronal map of synapse‐rich neuropils in the brain of Cataglyphis nodus including major connecting fiber systems. In addition, we examined neuronal tracts underlying the processing of visual information in more detail. This study revealed a total of 33 brain neuropils and 30 neuronal fiber tracts including six distinct tracts between the optic lobes and the cerebrum. We also discuss the importance of comparative studies on insect brain architecture for a profound understanding of neuronal networks and their function.
Increasing natural pest control in agricultural fields is an important aim of ecological intensification. Combined effects of landscape context and local placement of agri‐environmental schemes (AES) on natural pest control and within‐field distance functions of natural pest control agents have rarely been addressed but might affect the distribution of biocontrol providers. Importantly, it is currently unknown whether ecosystem services provided by adjacent AES are consistent for different crop types during crop rotation.
In this study, we assessed whether crop rotation from oilseed rape to cereals altered within‐field distance functions of ground‐dwelling predators from adjacent agri‐environmental fields along a gradient in landscape context. Additionally, we recorded crop pests, predation rates, parasitoids as well as crop yields on a total of 30 study sites.
Distance functions varied between trophic levels: Carabid richness decreased while densities of carabid beetles, staphylinid beetles as well as crop yields increased towards the field centres. Distance functions of parasitoids and pests were modulated by the amount of semi‐natural habitat in the surrounding landscape, while the effects of adjacent AES were limited.
Distance decay functions found for ground‐dwelling predators in oilseed rape in the previous year were not always present in cereals. Increasing distance to the field edge also increased effects of crop rotation on carabid beetle assemblages, indicating a source habitat function of field edges.
Synthesis and applications. Distance functions of natural pest control are not universal and the effects of agri‐environmental schemes (AES) in different adjacent crops during crop rotation vary and depend on ecological contrasts. A network of semi‐natural habitats and spatially optimized AES habitats can benefit pest control in agricultural landscapes, but constraints as a result of crop type need to be addressed by annually targeted, spatially shifting agri‐environment schemes for different crops.
Primates often consume either bark or cambium (inner bark) as a fallback food tocomplete their diet during periods of food scarcity. Wild chimpanzees exhibit greatbehavioral diversity across Africa, as studies of new populations frequently reveal.Since 2014, we have been using a combination of camera traps and indirect signs tostudy the ecology and behavior of wild chimpanzees (Pan troglodytes verus) in ComoéNational Park, Ivory Coast, to document and understand the behavioral adaptations thathelp them to survive in a savanna–forest mosaic landscape. We found that Comoéchimpanzees peel the bark of the buttresses of kapok tree (Ceiba pentandra) trees to eatthe cambium underneath. Individuals of all sex/age classes across at least six neigh-boring communities peeled the bark, but only during the late rainy season andbeginning of the dry season, when cambium may represent an important fallback food.Baboons (Papio anubis) also target the same trees but mainly eat the bark itself. Mostof the bark-peeling wounds onCeibatrees healed completely within 2 years, seeminglywithout any permanent damage. We recorded chimpanzees visiting trees in early stagesof wound recovery but leaving them unpeeled. Only 6% of peeled trees (N= 53) werereexploited after a year, suggesting that chimpanzees waited for the rest of the trees toregrow the bark fully before peeling them again, thus using them sustainably. Manyhuman groups of hunter-gatherers and herders exploited cambium sustainably in thepast. The observation that similar sustainable bark-peeling behavior evolved in bothchimpanzees and humans suggests that it has an important adaptive value in harshenvironments when other food sources become seasonally scarce, by avoiding thedepletion of the resource and keeping it available for periods of scarcity.
Background
The novel coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2(SARS-CoV-2), has escalated rapidly to a global pandemic stretching healthcare systems worldwide to their limits. Surgeonshave had to immediately react to this unprecedented clinical challenge by systematically repurposing surgical wards.
Purpose
To provide a detailed set of guidelines developed in a surgical ward at University Hospital Wuerzburg to safelyaccommodate the exponentially rising cases of SARS-CoV-2 infected patients without compromising the care of emergencysurgery and oncological patients or jeopardizing the well-being of hospital staff.
Conclusions
The dynamic prioritization of SARS-CoV-2 infected and surgical patient groups is key to preserving life whilemaintaining high surgical standards. Strictly segregating patient groups in emergency rooms, non-intensive care wards andoperating areas prevents viral spread while adequately training and carefully selecting hospital staff allow them to confidentlyand successfully undertake their respective clinical duties.
The opportunistic human pathogen Staphylococcus aureus causes serious infectious diseases that range from superficial skin and soft tissue infections to necrotizing pneumonia and sepsis. While classically regarded as an extracellular pathogen, S. aureus is able to invade and survive within human cells. Host cell exit is associated with cell death, tissue destruction, and the spread of infection. The exact molecular mechanism employed by S. aureus to escape the host cell is still unclear. In this study, we performed a genome-wide small hairpin RNA (shRNA) screen and identified the calcium signaling pathway as being involved in intracellular infection. S. aureus induced a massive cytosolic Ca\(^{2+}\) increase in epithelial host cells after invasion and intracellular replication of the pathogen. This was paralleled by a decrease in endoplasmic reticulum Ca\(^{2+}\) concentration. Additionally, calcium ions from the extracellular space contributed to the cytosolic Ca2+ increase. As a consequence, we observed that the cytoplasmic Ca\(^{2+}\) rise led to an increase in mitochondrial Ca\(^{2+}\) concentration, the activation of calpains and caspases, and eventually to cell lysis of S. aureus-infected cells. Our study therefore suggests that intracellular S. aureus disturbs the host cell Ca\(^{2+}\) homeostasis and induces cytoplasmic Ca\(^{2+}\) overload, which results in both apoptotic and necrotic cell death in parallel or succession.
IMPORTANCE Despite being regarded as an extracellular bacterium, the pathogen Staphylococcus aureus can invade and survive within human cells. The intracellular niche is considered a hideout from the host immune system and antibiotic treatment and allows bacterial proliferation. Subsequently, the intracellular bacterium induces host cell death, which may facilitate the spread of infection and tissue destruction. So far, host cell factors exploited by intracellular S. aureus to promote cell death are only poorly characterized. We performed a genome-wide screen and found the calcium signaling pathway to play a role in S. aureus invasion and cytotoxicity. The intracellular bacterium induces a cytoplasmic and mitochondrial Ca\(^{2+}\) overload, which results in host cell death. Thus, this study first showed how an intracellular bacterium perturbs the host cell Ca\(^{2+}\) homeostasis."
Rational drug design of Axl tyrosine kinase type I inhibitors as promising candidates against cancer
(2020)
The high level of Axl tyrosine kinase expression in various cancer cell lines makes it an attractive target for the development of anti-cancer drugs. In this study, we carried out several sets of in silico screening for the ATP-competitive Axl kinase inhibitors based on different molecular docking protocols. The best drug-like candidates were identified, after parental structure modifications, by their highest affinity to the target protein. We found that our newly designed compound R5, a derivative of the R428 patented analog, is the most promising inhibitor of the Axl kinase according to the three molecular docking algorithms applied in the study. The molecular docking results are in agreement with the molecular dynamics simulations using the MM-PBSA/GBSA implicit solvation models, which confirm the high affinity of R5 toward the protein receptor. Additionally, the selectivity test against other kinases also reveals a high affinity of R5 toward ABL1 and Tyro3 kinases, emphasizing its promising potential for the treatment of malignant tumors.
Ants build complex nest structures by reacting to simple, local stimuli. While underground nests result from the space generated by digging, some leaf- and grass-cutting ants also construct conspicuous aboveground turrets around nest openings. We investigated whether the selection of specific building materials occurs during turret construction in Acromyrmex fracticornis grass-cutting ants, and asked whether single building decisions at the beginning can modify the final turret architecture. To quantify workers' material selection, the original nest turret was removed and a choice between two artificial building materials, thin and thick sticks, was offered for rebuilding. Workers preferred thick sticks at the very beginning of turret construction, showed varying preferences thereafter, and changed to prefer thin sticks for the upper, final part of the turret, indicating that they selected different building materials over time to create a stable structure. The impact of a single building choice on turret architecture was evaluated by placing artificial beams that divided a colony's nest entrance at the beginning of turret rebuilding. Splitting the nest entrance led to the self-organized construction of turrets with branched galleries ending in multiple openings, showing that the spatial location of a single building material can strongly influence turret morphology.
The amyotrophic lateral sclerosis (ALS) neurodegenerative disorder has been associated with multiple genetic lesions, including mutations in the gene for fused in sarcoma (FUS), a nuclear-localized RNA/DNA-binding protein. Neuronal expression of the pathological form of FUS proteins in Caenorhabditis elegans results in mislocalization and aggregation of FUS in the cytoplasm, and leads to impairment of motility. However, the mechanisms by which the mutant FUS disrupts neuronal health and function remain unclear. Here we investigated the impact of ALS-associated FUS on motor neuron health using correlative light and electron microscopy, electron tomography, and electrophysiology. We show that ectopic expression of wild-type or ALS-associated human FUS impairs synaptic vesicle docking at neuromuscular junctions. ALS-associated FUS led to the emergence of a population of large, electron-dense, and filament-filled endosomes. Electrophysiological recording revealed reduced transmission from motor neurons to muscles. Together, these results suggest a pathological effect of ALS-causing FUS at synaptic structure and function organization.