Biology subjects

Muller, J.

Publications and source records attributed to Muller, J..

At least 19 recordsLinked to original sources

bioRxiv2026

Reversing PROTAC-induced ASH2L degradation reactivates proliferation in senescent cells

Nucleosomes control access to gene promoters. Histone H3 lysine 4 tri-methylation, catalyzed by 6 KMT2 complexes, correlates with accessible promoters and gene expression. The catalytic activity of KMT2 enzymes depends on an obligatory core complex with ASH2L being an essential subunit. We find that PROTAC induced depletion of ASH2L reduces H3K4me3, deregulates gene expression and prevents proliferation. Upon prolonged ASH2L loss, cells develop a senescent phenotype, a process linked to aging and disease. Competing the PROTAC reactivates ASH2L, reestablishes H3K4me3 at promoters and reverts gene expression changes. Cells reenter the cell cycle and resume proliferation, thereby reverting senescence. Structure-function studies demonstrate that these molecular and cellular consequences are primarily due to the loss of ASH2L functions associated with KMT2 complexes. Together, these findings indicate that stress inflicted by the loss of KMT2 catalytic activities promotes a reversible senescence phenotype, suggesting that the functions of KMT2 complexes are implicated in aging. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=127 SRC="FIGDIR/small/722411v1_ufig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@10ace2forg.highwire.dtl.DTLVardef@667c81org.highwire.dtl.DTLVardef@78039dorg.highwire.dtl.DTLVardef@13563be_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2025

Bumped kinase inhibitor BKI-1708 interferes in cytokinesis and drives baryzoite stage conversion in the cyst-forming apicomplexan parasites Toxoplasma gondii, Neospora caninum and Besnoitia besnoiti

Bumped kinase inhibitors (BKIs) have demonstrated safety and promising efficacy against various apicomplexan pathogens both in vitro and in vivo. However, in the closely related cyst-forming coccidians T. gondii, Neospora caninum and Besnoitia besnoiti, in vitro treatments with a range of BKIs induced the conversion of intracellular tachyzoites into atypical multinucleated complexes (MNCs), also named "baryzoites". In this study, baryzoites of T. gondii, N. caninum and B. besnoiti generated through exposure of tachyzoites to 2.5 {micro}M BKI-1708 were comparatively assessed. TEM showed that baryzoites contained multiple nuclei, clustered together and separated from the cytoplasmic organelles of newly formed zoites. These zoites do not have outer tachyzoite plasma membrane, were unable to complete cytokinesis, remained intracellular, and were enclosed by a parasitophorous vacuole membrane. TEM demonstrated the presence of an electron-dense cyst wall-like components only in T. gondii baryzoites. Species-specific differences in antigen expression were observed by immunofluorescence using specific antibodies. Comparative proteomic analysis revealed consistent downregulation of ribosomal proteins, proteins associated with secretory organelles, as well as of transcription and translation factors in all baryzoites. Bradyzoite-specific markers were upregulated only in T. gondii baryzoites. In addition, common orthologues of two alveolin-domain filament proteins (IMC7 and IMC12) and a hypothetical protein (TGME49_236950, NCLIV_050850, BESB_060040) were detected at higher abundance in all treated parasites. Overall, baryzoites exhibit distinct phenotypic and proteomic profiles, with ambiguous expression of tachyzoite and bradyzoite antigens, and lacking complete cellular division under drug pressure, suggesting a reversible response to stress rather than progression into a fully differentiated form. SignificanceApicomplexan parasites cause serious diseases worldwide, yet treatment options remain limited. A promising group of drugs are BKIs. We investigated how BKI-1708 affects threclosely related T. gondii, N. caninum, and B. besnoiti. Instead of killing the parasites, the drug induced the formation of multinucleated structures termed "baryzoites". These baryzoites exhibited ambiguous characteristics during the actively growing and dormant stages of the parasite life cycle and were unable to complete normal cell division. Moreover, we observed other key similarities and differences among species including downregulation of ribosomal proteins and transcription/translation factors, while only T. gondii displayed cyst wall formation. Microscopy and proteomics demonstrated that baryzoites represent a distinct stage that is formed upon drug pressure and promotes parasite survival during prolonged drug exposure. These findings highlight the unexpected ways parasites adapt to drug treatment and provide new insights into how BKIs exert their activities.

systems biology↗

bioRxiv2025

A Cell Type Enrichment Analysis Tool for Brain DNA Methylation Data (CEAM)

DNA methylation signatures are highly cell type-specific, yet most epigenome-wide association studies (EWAS) are performed on bulk tissue, potentially obscuring critical cell type-specific patterns. Existing computational tools for detecting cell type-specific DNAm changes are often limited by the accuracy of cell type deconvolution algorithms. Here, we introduce CEAM (Cell-type Enrichment Analysis for Methylation), a robust and interpretable framework for cell type enrichment analysis in DNA methylation data. CEAM applies over-representation analysis with cell type-specific CpG panels from Illumina EPIC arrays derived from nuclei-sorted cortical post-mortem brains from neurologically healthy aged individuals. The constructed CpG panels were systematically evaluated using both simulated datasets and published EWAS results from Alzheimers disease, Lewy body disease, and multiple sclerosis. CEAM demonstrated resilience to shifts in cell type composition, a common confounder in EWAS, and remained accurate across a wide range of differentially methylated positions, underscoring its flexibility. Application to existing EWAS findings generated in neurodegenerative diseases revealed enrichment patterns concordant with established disease biology, confirming CEAMs biological relevance. The workflow is publicly available as an interactive Shiny app (https://um-dementia-systems-biology.shinyapps.io/CEAM/) enabling rapid, interpretable analysis of cell type-specific DNAm changes from bulk EWAS.

genomics↗

bioRxiv2024

Bifidobacterium pseudocatenulatum capsular exopolysaccharide enhances systemic anti-tumour immunity in pre-clinical breast cancer

Gut microbes have merged as powerful regulators of cancer responses, with Bifidobacterium species and strains playing a key role in promoting anti-tumour immunity. While they represent promising candidates for cancer therapeutics, the specific underlying microbial mechanisms driving their efficacy remains poorly understood. In this study, we demonstrate the broad potential of Bifidobacterium species to inhibit breast cancer progression across multiple pre-clinical mouse models. We identify a novel strain, Bifidobacterium pseudocatenulatum 210, which induces systemic anti-tumour immunity and enhances responses to standard-of-care therapies via its cell surface capsular exopolysaccharide (EPS). B. pseudocatenulatum 210 EPS promotes dendritic cell activation and increases systemic cDC1 infiltration, leading to robust CD8+ T cell-mediated anti-tumour activity. Our findings position Bifidobacterium EPS as a novel class of therapeutic compounds with significant potential for cancer treatment.

cancer biology↗

bioRxiv2024

Development of sound production in Danionella cerebrum

Acoustic signaling, integral to intraspecific communication and reproductive behavior, undergoes notable changes during an animals ontogenetic development. The onset and progression of this maturation in fish remains poorly understood. Here, we investigate the ontogeny of acoustic communication in the micro glassfish Danionella cerebrum (DC), one of the smallest known vertebrates and an emerging model organism in neuroscience. Adult DC males produce audible clicks that appear in sequences with a repetition rate of 60 or 120 Hz, caused by consecutive unilateral or alternating bilateral compressions, respectively. To investigate the maturation of this ability, we performed long-term sound recordings and morphological studies of the DC sound production apparatus throughout its ontogenetic development. We found that DC start producing clicks during the second month of their lives and continually increase their abundance and structured repetition over the course of the following one to two months. The sound production machinery, including specialized bone and cartilage structures, start to form in male DC after approximately four weeks and prior to full maturation of the reproductive organs. While the DC clicks increase in amplitude with age and body size, click repetition rates of 60 and 120 Hz are stable throughout development. This suggests a fully developed central pattern generator in juvenile males, yet a continued maturation of the drumming apparatus capable of creating louder sounds.

animal behavior and cognition↗

bioRxiv2024

Gemcitabine and ATR inhibitors synergize to kill PDAC cells by blocking DNA damage response

The DNA-damaging agent gemcitabine (GEM) is a first-line treatment for pancreatic cancer but chemoresistance is frequently observed. Several clinical trials investigate the efficacy of GEM in combination with targeted drugs including kinase inhibitors but the experimental evidence for such rational is often unclear. Here, we phenotypically screened 13 human pancreatic adenocarcinoma (PDAC) cell lines against GEM in combination with 140 clinical kinase inhibitors and observed strong synergy for the ATR inhibitor Elimusertib in most cell lines. Dose-dependent phosphoproteome profiling of four ATR inhibitors following DNA damage induction by GEM revealed a strong block of the DNA damage response pathway including phosphorylated pS468 of CHEK1 as the underlying mechanism of drug synergy. The current work provides a strong rationale for why the combination of GEM and ATR inhibition may be useful for the treatment of PDAC patients and constitutes a rich phenotypic and molecular resource for further investigating effective drug combinations.

cancer biology↗

bioRxiv2024

(p)ppGpp-mediated GTP homeostasis ensures the survival and antibiotic tolerance of Staphylococcus aureus during starvation by preserving the proton motive force

Upon nutrient limitation bacteria enter a nongrowing state, which allow bacterial survival and antibiotic tolerance. The mechanisms whether and how the messenger molecule (p)ppGpp contributes to the transition in Firmicutes is debated. Here we show for Staphylococcus aureus that (p)ppGpp-dependent restriction of the GTP pool is essential for the culturability of starved cells and for antibiotic tolerance. Elevated GTP levels in a starving (p)ppGpp-deficient mutant lead to a division-incompetent, dormant state characterized by reduced metabolic activity and alterations in membrane function and architecture. GTP level control of nucleotide sensitive promoters result in transcriptional downregulation of gene of the TCA cycle and electron transport chain. Increasing transcription of qoxABCD, a terminal oxidase of the respiratory chain, through mutation of the transcriptional start site partially restored the culturability of the (p)ppGpp-deficient mutant. Furthermore, we showed that the maintenance of proton motive force under nutritional stress contributes to antibiotic tolerance, supporting the idea of applying (p)ppGpp or PMF inhibitors to combat antibiotic-tolerant bacteria.

microbiology↗

bioRxiv2023

Quantifying the strength of viral fitness tradeoffs between hosts: A meta-analysis of pleiotropic fitness effects

The range of hosts a given virus can infect is widely presumed to be limited by fitness tradeoffs between alternative hosts. These fitness tradeoffs may arise naturally due to antagonistic pleiotropy if mutations that increase fitness in one host tend to decrease fitness in alternate hosts. Yet there is also growing recognition that positive pleiotropy may be more common than previously appreciated. With positive pleiotropy, mutations have concordant fitness effects such that a beneficial mutation can simultaneously increase fitness in different hosts, providing a genetic mechanism by which selection can overcome fitness tradeoffs. How readily evolution can overcome fitness tradeoffs therefore depends on the overall distribution of mutational fitness effects between hosts, including the relative frequency of antagonistic versus positive pleiotropy. We therefore conducted a systematic meta-analysis of the pleiotropic fitness effects of viral mutations reported in different hosts. Our analysis indicates that while both antagonistic and positive pleiotropy are common, fitness effects are overall positively correlated between hosts and unconditionally beneficial mutations are not uncommon. Moreover, the relative frequency of antagonistic versus positive pleiotropy may simply reflect the underlying frequency of beneficial and deleterious mutations in individual hosts. Given a mutation is beneficial in one host, the probability that it is deleterious in another host is roughly equal to the probability that any mutation is deleterious, suggesting there is no natural tendency towards antagonistic pleiotropy. The widespread prevalence of positive pleiotropy suggests that many fitness tradeoffs may be readily overcome by evolution given the right selection pressures. Lay summary Evolutionary theory suggests that fitness tradeoffs between alternative environments constrain the potential for organisms to simultaneously adapt to multiple environments. Likewise, fitness tradeoffs between alternative hosts are widely believed to limit the ability of viruses to adapt to multiple hosts and thereby expand their host range. How strongly viruses are constrained by such tradeoffs will largely depend on the fitness effects of new mutations. Fitness tradeoffs may inevitably constrain viral evolution if mutations that increase fitness in one host tend to decrease fitness in alternative hosts. However, mutations can sometimes increase fitness in multiple hosts, allowing viruses to adapt to new hosts without paying fitness costs. Geneticists refer to these two scenarios as antagonistic and positive pleiotropy depending on whether mutations have opposite or concordant fitness effects. Because the relative frequency of antagonistic versus positive pleiotropy is centrally important to viral evolution, we conducted a systematic meta-analysis of the fitness effects of mutations reported in different hosts. Our analysis reveals that cases of positive pleiotropy where mutations have beneficial effects in more than one host may be sufficiently common for evolution to resolve many apparent fitness tradeoffs between hosts.

evolutionary biology↗

bioRxiv2023

Transformation of cereal grains: Botanical and chemical analysis of food residues encrusted on pottery from the Funnel Beaker settlement of Oldenburg LA 77, northern Germany

An integrated botanical and chemical approach is used to study surface residues on Funnel Beaker ceramics from the site of Oldenburg LA 77, in northern Germany. Organic residues were discovered adhering to fragments of thick-walled, undecorated ceramic vessels (n=19) and ceramic discs (n=2). The surface residues were studied using scanning electron microscopy (SEM), to examine remains of cereals and other plant tissues that survived food preparation and cooking, and using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and direct time-resolved mass spectrometry (DTMS), to chemically identify specific food components. The SEM results show a reoccurring presence of cereal grain (emmer and barley) and one case of co-occurrence of emmer and fat-hen seeds. The SEM evidence for the use of sprouted emmer grain and milk-ripe barley from the Oldenburg residues greatly enhances our understanding of Neolithic foodways in northwestern Europe. The ATR-FTIR results showed that roughly a third of the surface residues contain traces of the original foods prepared or processed and DTMS results confirm that most of the residues primarily contain polysaccharides and a minimal amount of plant protein and that they lack lipids. Only one residue presents minor indications for a (partly) animal origin. The ceramic vessels were thus used almost exclusively for the processing or cooking of cereal grains. This study offers an intimate view of the cuisine and cooking practices (and in some cases their seasonal timing) in an early agricultural village located in a marginal farming region on the south coast of the Baltic Sea.

plant biology↗

bioRxiv2023

The Endothelium Modulates the Prothrombotic Phenotype of Factor V Leiden: Evidence from an Ex Vivo Model

BackgroundClinical expressivity of the thrombophilic factor V Leiden (FVL) mutation is highly variable. Increased activated protein C (APC) formation in response to thrombin formation has been observed in asymptomatic FVL carriers in vivo. Here we further explored this association using a recently developed endothelial colony forming cell (ECFC)-based ex-vivo model. MethodsECFCs and citrated plasma were obtained from FVL carriers with/without previous venous thromboembolism (VTE+/-, n=7 each) and seven healthy controls. Coagulation was activated by tissue factor in defibrinated recalcified plasma added to confluent cell cultures. Thrombin and APC concentration were measured over time and the respective areas under the curve (AUC) calculated. Additionally, inhibition kinetics of exogenously added APC and APC sensitivity of the prothrombinase complex were measured in plasma. Expression of thrombomodulin and endothelial protein C receptor (EPCR) on ECFCs was assessed using cell-based enzyme-linked immunosorbent assays. ResultsIn autologous plasma on ECFCs, the APC response to thrombin formation (AUC APC/AUC thrombin), was higher in FVL VTE-than FVL VTE+ patients (0.138 versus 0.028, P=0.026). APC inactivation kinetics, APC sensitivity, and thrombomodulin/EPCR expression on ECFCs did not differ between these cohorts and compared to healthy controls. Cross-over experiments with plasma from FVL VTE- and FVL VTE+ patients on non-FVL ECFCs yielded indistinguishable results. In contrast, in normal plasma on FVL VTE-ECFCs the APC response remained significantly higher than on FVL VTE+ ECFCs (0.052 versus 0.022, P=0.011). ConclusionsConsistent with results from previous in vivo experiments, APC response rates to thrombin formation were higher in asymptomatic FVL carriers compared to those with previous VTE. Our observations suggest that this increased APC response is driven by the endothelium. Further studies are warranted to elucidate yet unknown endothelial mechanisms that might modulate the clinical expressivity of FVL.

pathology↗

bioRxiv2023

Admixture as a source for HLA variation in Neolithic European farming communities

The northern European Neolithic is characterized by two major demographic events: immigration of early farmers (EF) from Anatolia (5500 BCE) and their admixture (from [~]4200 BCE) with western hunter-gatherers (WHG) forming late farmers (LF). The influence of this admixture event on variation in the immune-relevant human leukocyte antigen (HLA) region is understudied. Here, we conducted population and immunogenetic analyses on 83 individuals from six EF and LF sites located in present-day Germany. We observed significant shifts in HLA allele frequencies from EF to LF. The HLA diversity increased from EF to LF, likely due to admixture with WHG. However, it was considerably lower than in modern populations. Both EF and LF exhibited a relatively narrow HLA allele spectrum compared to today. This coincides with sparse traces of pathogen DNA, potentially indicating a lower pathogen pressure at the time. We additionally noted that LF resulted from sex-biased admixture from male WHG. TEASERMore restricted HLA allele spectrum and lower diversity in Neolithic farmers than in modern populations

genetics↗

bioRxiv2023

Life and death in Trypillia times: Interdisciplinary analyses of the exceptional human remains from the settlement of Kosenivka, Ukraine (3700-3600 BCE)

We present an interdisciplinary analysis of finds from the Trypillia settlement of Kosenivka, Ukraine (ca. 3700-3600 BCE, Trypillia C1), that links information on human, faunal, and botanical remains with archaeological data to provide exceptionally detailed insights into life and death at a Trypillia mega-site. We obtained osteological, palaeopathological, and histotaphonomic data from human bone fragments; performed carbon and nitrogen stable isotopic analysis of human and animal bone to calculate food webs with the software FRUITS; and modelled newly generated radiocarbon dates to refine the sites chronology. The biological profile of seven identified individuals, some of whom suffered from disease symptoms common in the Chalcolithic, represents a demographic cross-section of the population. The analysis of perimortem cranial trauma suffered by two individuals suggest cases of interpersonal conflict. Food web calculations demonstrate the large contribution of cereals to the protein component of the human diet, which is supported by dental observations, and we suggest that livestock were a major manure producer for crop cultivation. The most probable scenario for the formation of the Kosenivka find assemblage is a deathly fire event. This makes the site a rare example where the archaeological and osteological results can be used to reconstruct a minimum number of house inhabitants. Following a literature review, we contextualise our analysis by discussing the general lack of human remains from Early and Middle Trypillia sites. The individuals from Kosenivka form part of the less than 0.05% of the total estimated Trypillia population that is represented skeletally; its members were deposited within settlements in the Middle Trypillia stage (until C1), preceding the shift to extramural burials in its late phase (C2). Our detailed results indicate the huge explanatory potential that has yet to be unlocked in the rare and often poorly preserved bioarchaeological archives of the Cucuteni-Trypillia phenomenon.

evolutionary biology↗

bioRxiv2023

Nanobodies against SARS-CoV-2 reduced virus load in the brain of challenged mice and neutralized Wuhan, Delta and Omicron Variants

In this work, we developed llama-derived nanobodies (Nbs) directed to the receptor binding domain (RBD) and other domains of the Spike (S) protein of SARS-CoV-2. Nanobodies were selected after the biopanning of two VHH-libraries, one of which was generated after the immunization of a llama (lama glama) with the bovine coronavirus (BCoV) Mebus, and another with the full-length pre-fused locked S protein (S-2P) and the RBD from the SARS-CoV-2 Wuhan strain (WT). Most of the neutralizing Nbs selected with either RBD or S-2P from SARS-CoV-2 were directed to RBD and were able to block S- 2P/ACE2 interaction. Three Nbs recognized the N-terminal domain (NTD) of the S-2P protein as measured by competition with biliverdin, while some non-neutralizing Nbs recognize epitopes in the S2 domain. One Nb from the BCoV immune library was directed to RBD but was non-neutralizing. Intranasal administration of Nbs induced protection ranging from 40% to 80% against COVID-19 death in k18-hACE2 mice challenged with the WT strain. Interestingly, protection was not only associated with a significant reduction of virus replication in nasal turbinates and lungs, but also with a reduction of virus load in the brain. Employing pseudovirus neutralization assays, we were able to identify Nbs with neutralizing capacity against the Alpha, Beta, Delta and Omicron variants. Furthermore, cocktails of different Nbs performed better than individual Nbs to neutralize two Omicron variants (B.1.529 and BA.2). Altogether, the data suggest these Nbs can potentially be used as a cocktail for intranasal treatment to prevent or treat COVID-19 encephalitis, or modified for prophylactic administration to fight this disease.

immunology↗

bioRxiv2023

Generation of human cerebral organoids with a structured outer subventricular zone

Mammalian outer radial glia (oRG) emerge as cortical progenitor cells that directly support the development of an enlarged outer subventricular zone (oSVZ) and, in turn, the expansion of the neocortex. The in vitro generation of oRG is essential to model and investigate the underlying mechanisms of human neocortical development and expansion. By activating the STAT3 pathway using LIF, which is not produced in guided cortical organoids, we developed a cerebral organoid differentiation method from human pluripotent stem cells (hPSCs) that recapitulates the expansion of a progenitor pool into the oSVZ. The structured oSVZ is composed of progenitor cells expressing specific oRG markers such as GFAP, LIFR, HOPX, which closely matches human oRG in vivo. In this microenvironment, cortical neurons showed faster maturation with enhanced metabolic and functional activity. Incorporation of hPSC-derived brain vascular LIF- producing pericytes in cerebral organoids mimicked the effects of LIF treatment. These data indicate that the cellular complexity of the cortical microenvironment, including cell-types of the brain vasculature, favors the appearance of oRG and provides a platform to routinely study oRG in hPSC-derived brain organoids.

developmental biology↗

bioRxiv2021

Bacterial growth, communication and guided chemotaxis in 3D bioprinted hydrogel environments

Bioprinting of engineered bacteria is of great interest for applications of synthetic biology in the context of living biomaterials, but so far only few viable approaches are available for the printing of gels hosting live Escherichia coli bacteria. Here we develop a gentle bioprinting method based on an alginate/agarose bioink that enables precise printing of E.coli into three-dimensional hydrogel structures up to 10 mm in height. Addition of a calcium peroxide-based oxygen generation system enables maturation of fluorescent proteins deep within the printed structures. We utilize spatial patterning with the bioprinter to control different types of chemical interaction between bacteria. We first show quorum sensing-based chemical communication between engineered sender and receiver bacteria placed at different positions inside the bioprint, and then demonstrate the fabrication of barrier structures defined by non-motile bacteria that can guide the movement of chemotactic bacteria inside a gel.

bioengineering↗

bioRxiv2021

Synergy between vesicular and non-vesicular gliotransmission regulates synaptic plasticity and working memory

Astrocytes are an active element of brain signalling, capable of release of small molecule gliotransmitters by vesicular and channel-mediated mechanisms. However, specific physiological roles of astroglial exocytosis of glutamate and D-Serine remain controversial. Our data demonstrate that cortical astrocytes can release glutamate and D-Serine by combination of SNARE-dependent exocytosis and non-vesicular mechanisms dependent on TREK-1 and Best1 channels. Astrocyte-derived glutamate and D-serine elicited complex multicomponent phasic response in neocortical pyramidal neurons, which is mediated by extra-synaptic GluN2B receptors. Impairment of either pathway of gliotransmission (in the TREK1 KO, Best-1 KO or dnSNARE mice) strongly affected the NMDAR-dependent long-term synaptic plasticity in the hippocampus and neocortex. Moreover, impairment of astroglial exocytosis in dnSNARE mice led to the deficit in the spatial working memory which was rescued by environmental enrichment. We conclude that synergism between vesicular and non-vesicular gliotransmission is crucial for astrocyte-neuron communication and astroglia-driven regulation of synaptic plasticity and memory. HighlightsO_LIAstrocytes in situ release glutamate via exocytosis and channel-mediated release. C_LIO_LIAstroglia-derived glutamate and D-Serine activate phasic NMDAR currents in neurons C_LIO_LIBoth vesicular and non-vesicular gliotransmission are required for synaptic plasticity C_LIO_LIImpaired exocytosis of gliotransmitters causes deficit in working memory C_LI

neuroscience↗

bioRxiv2021

Climate, latitude, and land cover predict flying insect biomass across a German malaise trap network

O_LIAmong the many concerns for biodiversity in the Anthropocene, recent reports of flying insect loss are particularly alarming, given their importance as pollinators and as a food source for many predators. Few insect monitoring programs cover large spatial scales required to provide more generalizable estimates of insect responses to global change drivers. C_LIO_LIWe ask how climate and surrounding habitat affect flying insect biomass and day of peak biomass using data from the first year of a new standardized distributed monitoring network at 84 locations across Germany comprising spatial gradient of land-cover types from protected to urban areas. C_LIO_LIFlying insect biomass increased linearly with monthly temperature across Germany. However, the effect of temperature on flying insect biomass flipped to negative in the hot months of June and July when local temperatures most exceeded long-term averages. C_LIO_LILand-cover explained little variation in insect biomass, but biomass was lowest in forested sites. Grasslands, pastures and orchards harbored the highest insect biomass. The date of peak biomass was primarily driven by surrounding land-cover type, with grasslands especially having earlier insect biomass phenologies. C_LIO_LIStandardized, large-scale monitoring is pivotal to uncover underlying processes of insect decline and to develop climate-adapted strategies to promote insect diversity. In a temperate climate region, we find that the benefits of temperature on flying insect biomass diminish in a German summer at locations where temperatures most exceeded long-term averages. These results highlighting the importance of local adaptation in climate change-driven impacts on insect communities. C_LI

ecology↗

bioRxiv2021

Choosing optimal trigger points for ex situ, in toto conservation of single population threatened species

Many endangered species exist in only a single population, and almost all species that go extinct will do so from their last remaining population. Understanding how to best conserve these single population threatened species (SPTS) is therefore a distinct and important task for threatened species conservation science. As a last resort, managers of SPTS may consider taking the entire population into captivity - ex situ, in toto conservation. In the past, this choice has been taken to the great benefit of the SPTS, but it has also lead to catastrophe. Here, we develop a decision-support tool for planning when to trigger this difficult action. Our method considers the uncertain and ongoing decline of the SPTS, the possibility that drastic ex situ action will fail, and the opportunities offered by delaying the decision. Specifically, these benefits are additional time for ongoing in situ actions to succeed, and opportunities for the managers to learn about the system. To illustrate its utility, we apply the decision tool to four retrospective case-studies of declining SPTS. As well as offering support to this particular decision, our tool illustrates why trigger points for difficult conservation decisions should be formulated in advance, but must also be adaptive. A trigger-point for the ex situ, in toto conservation of a SPTS, for example, will not take the form of a simple threshold abundance.

ecology↗