Biology subjects

Burger, J.

Publications and source records attributed to Burger, J..

At least 19 recordsLinked to original sources

bioRxiv2026

Intravenously Delivered Lipid Nanoparticles Access Acute Spinal Cord Injury via Disrupted Vasculature

Trauma to the spinal cord disrupts the blood-spinal cord barrier and triggers a secondary injury cascade characterized by inflammation and progressive neuronal and glial cell death. Therapeutic cytokines and growth factors have shown promise as a treatment in preclinical studies, though their clinical translation is limited by short protein half-lives and the need for invasive intraspinal administration. Lipid nanoparticle-mediated delivery of mRNA offers an alternative strategy that enables transient protein production. Here, we investigated whether intravenously administered mRNA-lipid nanoparticles could leverage the injury-induced disruption of the blood-spinal cord barrier to access the injured spinal cord for local transgene expression. After spinal cord injury in a rat, lipid nanoparticles loaded with reporter mRNA were administered intravenously, and transgene expression was quantified in the spinal cord and peripheral organs. Intravenous delivery within a 6-hours post-injury resulted in local transgene expression in the injured spinal cord, demonstrating that mRNA-lipid nanoparticles cross the disrupted blood-spinal cord barrier. Transgene expression was observed in astrocytes, oligodendrocytes, microglia, and neurons, detected within 3 hours and remained elevated for up to 5 days post-injury. These findings demonstrate that systemic mRNA-lipid nanoparticles delivery exploit transient blood-spinal cord barrier disruption to achieve local gene expression in the injured spinal cord.

neuroscience↗

bioRxiv2026

Promises and limitations of current ancient human epigenetic clocks

Age-at-death estimation of archaeological human remains is central to palaeodemographic research yet remains particularly challenging for adults where osteological methods often produce imprecise age ranges. Epigenetic clocks can accurately predict chronological age in modern humans, but their applicability to ancient human DNA is unclear due to data limitation and indirect methylation inference. Here, we evaluate the performance of existing epigenetic clocks on reconstructed ancient human methylomes combining high-coverage genomic data and a correction framework adapted to mitigate damage-derived sequence bias. Across multiple CpG window sizes, neither direct clock application nor regression-based retraining produced reliable continuous age-at-death estimates. Reframing age inference as adult-subadult classification did not return statistically supported age classes either. In contrast, sex estimation based on X-chromosome methylation achieved perfect accuracy, before and after correction. Together, these results indicate that current palaeo-epigenetic approaches reliably recover global biological signals but are not sufficiently sensitive to capture gradual, age-related variation in humans. Estimating age-at-death from ancient methylomes will therefore require methodological advances beyond correction alone, including reference data and improved models for inferring damage-derived epigenetic signals.

genomics↗

bioRxiv2024

Local increases in admixture with hunter-gatherers followed the initial expansion of Neolithic farmers across continental Europe

The replacement of hunter-gatherer lifestyles by agriculture represents a pivotal change in human history. The initial stage of this Neolithic transition in Europe was instigated by the migration of farmers from Anatolia and the Aegean basin. In this study, we modeled the expansion of Neolithic farmers into Central Europe from Anatolia, along the Continental route of dispersal. We employed spatially explicit simulations of palaeogenomic diversity and high-quality palaeogenomic data from 67 prehistoric individuals to assess how population dynamics between indigenous European hunter-gatherers and incoming farmers varied across space and time. Our results demonstrate that admixture between the two groups increased locally over time at each stage of the Neolithic expansion along the Continental route. We estimate that the effective population size of farmers was about five times that of the hunter-gatherers. Additionally, we infer that sporadic long distance migrations of early farmers contributed to their rapid dispersal, while competitive interactions with hunter-gatherers were limited. TeaserThe first farmers of continental Europe increasingly admixed over time with indigenous hunter-gatherers.

genomics↗

bioRxiv2024

Targeted NAD+ Delivery for Intimal Hyperplasia and Re-endothelialization: A Novel Anti-restenotic Therapy Approach

Endovascular interventions often fail due to restenosis, primarily caused by smooth muscle cell (SMC) proliferation, leading to intimal hyperplasia (IH). Current strategies to prevent restenosis are far from perfect and impose significant collateral damage on the fragile endothelial cell (EC), causing profound thrombotic risks. Nicotinamide adenine dinucleotide (NAD+) is a co-enzyme and signaling substrate implicated in redox and metabolic homeostasis, with a pleiotropic role in protecting against cardiovascular diseases. However, a functional link between NAD+ repletion and the delicate duo of IH and EC regeneration has yet to be established. NAD+ repletion has been historically challenging due to its poor cellular uptake and low bioavailability. We have recently invented the first nanocarrier that enables direct intracellular delivery of NAD+ in vivo. Combining the merits of this prototypic NAD+-loaded calcium phosphate (CaP) nanoparticle (NP) and biomimetic surface functionalization, we created a biomimetic P-NAD+-NP with platelet membrane coating, which enabled an injectable modality that targets IH with excellent biocompatibility. Using human cell primary culture, we demonstrated the benefits of NP-assisted NAD+ repletion in selectively inhibiting the excessive proliferation of aortic SMC, while differentially protecting aortic EC from apoptosis. Moreover, in a rat balloon angioplasty model, a single-dose treatment with intravenously injected P-NAD+-NP immediately post angioplasty not only mitigated IH, but also accelerated the regeneration of EC (re-endothelialization) in vivo in comparison to control groups (i.e., saline, free NAD+ solution, empty CaP-NP). Collectively, our current study provides proof-of-concept evidence supporting the role of targeted NAD+ repletion nanotherapy in managing restenosis and improving re-endothelialization.

pathology↗

bioRxiv2022

An alpaca-derived nanobody neutralizes the SARS-CoV-2 omicron variant

The SARS-CoV2 Omicron variant sub-lineages spread rapidly through the world, mostly due to their immune-evasive properties. This has put a significant part of the population at risk for severe disease and underscores the need for anti-SARS-CoV-2 agents that are effective against emergent strains in vulnerable patients. Camelid nanobodies are attractive therapeutic candidates due to their high stability, ease of large-scale production and potential for delivery via inhalation. Here, we characterize the RBD-specific nanobody W25, which we previously isolated from an alpaca, and show superior neutralization activity towards Omicron lineage BA.1 in comparison to all other SARS-CoV2 variants. Structure analysis of W25 in complex with the SARS-CoV2 spike surface glycoprotein shows that W25 engages an RBD epitope not covered by any of the antibodies previously approved for emergency use. Furthermore, we show that W25 also binds the spike protein from the emerging, more infectious Omicron BA.2 lineage with picomolar affinity. In vivo evaluation of W25 prophylactic and therapeutic treatments across multiple SARS-CoV-2 variant infection models, together with W25 biodistribution analysis in mice, demonstrates favorable pre-clinical properties. Together, these data endorse prioritization of W25 for further clinical development.

microbiology↗

bioRxiv2022

Melon pan-genome and multi-parental framework for high-resolution trait dissection

Linking between genotype and phenotype is a fundamental goal in biology and requires robust data for both layers. The prominent increase in plant genome sequencing and comparisons of multiple related individuals, exposed the abundance of structural genomic variation and suggest that a single reference genome cannot represent the complete sequence diversity of a crop species, leading to the expansion of the pan-genome concept. For high-resolution forward genetics, this unprecedented access to genomic variation should be paralleled by availability and phenotypic characterization of genetic diversity, and effective integration between these layers. Here, we describe a multi-parental framework for trait dissection in melon, leveraging a novel pan-genome constructed for this crop. Melon (Cucumis melo L.) is an important crop from the Cucurbitaceae family, which display extensive phenotypic variation available for breeding. A diverse core set of 25 founder lines (MelonCore25) was sequenced using a combination of short and long-read technologies and their genomes were assembled de novo. The construction of a melon pan-genome exposed substantial variation in genome size and structure, including detection of ~300,000 structural variants and ~9 million SNPs. A half-diallel derived set of 300 F2 populations representing all possible MelonCore25 parental combinations was constructed as framework for trait dissection through integration with the pan-genome. We demonstrate the potential of this unified framework for genetic analysis of various melon traits, including rind color and mottling pattern, fruit sugar content and resistance to fungal diseases. We anticipate that utilization of this integrated resource will enhance genetic dissection of important traits and accelerate melon breeding. Significance statementPan-genomes aim to address the abundance of genome structural variation within species for improved genomic analyses. New pan-genome, constructed from de novo genome assemblies of 25 diverse melon (Cucumis melo L.) accessions is integrated with a half-diallel derived set of 300 F2 populations representing all possible parental combinations. The potential of this unified multi-parental trait dissection framework for melon genetics and breeding is presented.

genetics↗

bioRxiv2022

Was fishing village of Lepenski Vir built by Europe's first farmers?

Today, it is widely accepted that agriculture and settled village life arrived in Europe as a cultural package, carried by people migrating from Anatolia and the Aegean Basin. The putative fisher-forager site of Lepenski Vir in Serbia has long been acknowledged as an exception to this model. Here, the Mesolithic-Neolithic transition - possibly inspired by interaction with the new arrivals - was thought to have taken place autochthonously on site. Our reinterpretation, based on ancient genomes, as well as archaeological and isotopic evidence, revisits this conclusion, indicating that here too, house construction, early village society and agriculture were primarily associated with Europes first farmers, thus challenging the long-held interpretation of Lepenski Vir as a Mesolithic community that adopted Neolithic practices. A detailed timeline of population changes at the site suggests that Aegean incomers did not simply integrate into an established Mesolithic society, rather founded new lineages and households. Iron Gates foragers and their admixed descendants appear to have been buried largely separately, on the fringes of the settlement, their diet showing no major shift from aquatic to terrestrial food resources.

genomics↗

bioRxiv2022

Between fishing and farming: palaeogenomic analyses reveal cross-cultural interactions triggered by the arrival of the Neolithic in the Danube Gorges

While early Neolithic populations in Europe were largely descended from early Aegean farmers, there is also evidence of episodic gene flow from local Mesolithic hunter-gatherers into early Neolithic communities. Exactly how and where this occurred is still unknown. Here we report direct evidence for admixture between the two groups at the Danube Gorges in Serbia. Analysis of palaeogenomes recovered from skeletons revealed that second-generation mixed individuals were buried amidst individuals whose ancestry was either exclusively Aegean Neolithic or exclusively local Mesolithic. The mixed ancestry is also reflected in a corresponding mosaic of grave goods. With its deep sequence of occupation and its unique dwellings that suggest at least semi-sedentary occupation since the late Mesolithic, the area of the Danube Gorges has been at the center of the debate about the contribution of Mesolithic societies to the Neolithisation of Europe. As suggested by our data, which were processed exclusively with uncertainty-aware bioinformatic tools, it may have been precisely in such contexts that close interactions between these societies were established, and Mesolithic ancestry and cultural elements were assimilated.

genomics↗

bioRxiv2022

Structure and mechanism of a novel cytomegaloviral DCAF mediating interferon antagonism

Human cytomegalovirus (CMV) is a highly relevant and ubiquitously distributed human pathogen. Its rodent counterparts such as mouse and rat CMV serve as common infection models. Here, we conducted the first global proteome profiling of rat CMV-infected cells and uncovered a pronounced loss of the transcription factor STAT2, which is crucial for interferon signalling. Deletion mutagenesis documented that STAT2 is targeted by the viral protein E27. Cellular and in vitro analyses showed that E27 exploits host-derived Cullin4-RING ubiquitin ligases (CRL4) to induce poly-ubiquitylation and proteasomal degradation of STAT2. A cryo-electron microscopic structure determination revealed how E27 mimics molecular surface properties of cellular CRL4 substrate receptors called DDB1- and Cullin4-associated factors (DCAFs) to displace them from the catalytic core of CRL4. Moreover, structural analyses elucidated the mechanism of STAT2 recruitment and indicate that E27-binding additionally disturbs STAT2-dependent interferon signalling by occupying its IRF9 binding interface. For the first time, these data provide structural insights into cytomegalovirus-encoded interferon antagonism and establish an atomic model for STAT2 counteraction by CRL4 misappropriation with important implications for viral immune evasion.

biochemistry↗

bioRxiv2022

CD4 binding-site antibodies induced by a subtype B HIV-1 envelope trimer

In the last decade considerable advances have been made towards the design of HIV-1 vaccines that induce neutralizing antibodies (NAbs). Despite the progress, no vaccine is able to consistently elicited broadly neutralizing antibodies (bNAbs). Here we present a case study of a rabbit that was immunized with a subtype B native like envelope glycoprotein (Env) trimer, AMC016 SOSIP.v4.2, with a dense and intact glycan shield, followed by a trivalent combination of subtype B trimers. After the priming phase serum from this animal neutralized several heterologous subtype B neutralization resistant (tier 2) viruses. Subsequent immunization with the trivalent combination of subtype B trimers further increased the breadth and potency of the NAb response. EM based polyclonal epitope mapping revealed that a cross reactive CD4 binding-site (CD4bs) antibody response, that was present after priming with the monovalent trimer and boosting with the trivalent combination, was most likely responsible for the broad neutralization. While anecdotal, this study provides proof-of-concept that native-like Env trimers are capable of inducing CD4bs-directed bNAb responses and should guide efforts to improve the consistency with which such responses are generated.

immunology↗

bioRxiv2021

Underground Heterosis for Melons Yield

Heterosis, the superiority of hybrids over their parents, is a major genetic force associated with plant fitness and crop yield enhancement. Understanding and predicting heterosis is crucial for evolutionary biology, as well as for plant and animal breeding. We investigated root-mediated yield heterosis in melons (Cucumis melo) by characterizing common variety grafted onto 190 hybrid rootstocks resulting from crossing 20 diverse inbreds in a diallel-mating scheme. Hybrid rootstocks improved yield by more than 40% compared to their parents and the best hybrid outperformed the reference commercial variety by 65% under both optimal and minimal irrigation treatments. To characterize the genetics of the underground heterosis we conducted whole-genome re-sequencing of the 20 founder lines, and showed that parental genetic distance was no predictor for the level of heterosis. Through inference of the 190 hybrids genotypes from their parental genomes, followed by genome-wide association analysis, we mapped multiple root-mediated yield QTLs. The yield enhancement of the four best-performing hybrid rootstocks was validated in multiple experiments with four different scion varieties. While root biology is receiving increased attention, most of the research is conducted using plants not amenable to grafting and, as a result, it is difficult to separate root and shoot effects. Here, we use the rich genetic and genomic resources of Cucumis melo, where grafting is a common practice, to dissect a unique phenomenon of root-mediated yield heterosis, by directly evaluating in the field the contribution of the roots to fruit yield. Our grafting approach is inverted to the common roots genetics research path that focuses mainly on variation in root system architecture rather than the ultimate root-mediated whole-plant performance, and is a step towards discovery of candidate genes involved in root function and yield enhancement. HighlightWe show that yield heterosis is significant in melon and controlled independently above and underground. Using common-scion grafting approach, we find that heritable rootstock-mediated variation in a diallel population is associated with substantial fruit yield heterosis.

plant biology↗

bioRxiv2020

Immunofocusing and enhancing autologous Tier-2 HIV-1 neutralization by displaying Env trimers on two-component protein nanoparticles

The HIV-1 envelope glycoprotein trimer is poorly immunogenic because it is covered by a dense glycan shield. As a result, recombinant Env glycoproteins generally elicit inadequate antibody levels that neutralize clinically-relevant, neutralization-resistant (Tier-2) HIV-1 strains. Multivalent antigen presentation on nanoparticles is an established strategy to increase vaccine-driven immune responses. However, due to nanoparticle instability in vivo, the display of non-native Env structures, and the inaccessibility of many neutralizing antibody (NAb) epitopes, the effects of nanoparticle display have been modest for Env trimers. Here, we generated two-component self-assembling protein nanoparticles presenting twenty SOSIP trimers of the clade C Tier-2 genotype 16055. An immunization study in rabbits demonstrated that these nanoparticles induced 60-fold higher autologous Tier-2 NAb titers than the corresponding SOSIP trimers. Epitope mapping revealed that nanoparticle presentation focused antibody responses to an immunodominant apical epitope. Thus, these nanoparticles are a promising platform to improve the immunogenicity of Env trimers with apex-proximate NAb epitopes.

microbiology↗

bioRxiv2020

The mixed genetic origin of the first farmers of Europe

The precise genetic origins of the first Neolithic farming populations, as well as the processes and the timing of their differentiation, remain largely unknown. Based on demogenomic modeling of high-quality ancient genomes, we show that the early farmers of Anatolia and Europe emerged from a multiphase mixing of a Near Eastern population with a strongly bottlenecked Western hunter-gatherer population after the Last Glacial Maximum. Moreover, the population branch leading to the first farmers of Europe and Anatolia is characterized by a 2,500-year period of extreme genetic drift during its westward range expansion. Based on these findings, we derive a spatially explicit model of the population history of Southwest Asia and Europe during the late Pleistocene and early Holocene. One-Sentence SummaryEarly European farmers emerged from multiple post LGM mixtures and experienced extreme drift during their westward expansion.

evolutionary biology↗

bioRxiv2020

Kinship, acquired and inherited status, and population structure at the Early Bronze Age Mokrin necropolis in northern Serbia.

Twenty-four ancient genomes with an average sequencing coverage of 0.85{+/-}0.25 X were produced from the Mokrin necropolis, an Early Bronze Age (2,100-1,800 BC) Maros culture site in Serbia, to provide unambiguous identification of biological sex, population structure, and genetic kinship between individuals. Of the 24 investigated individuals, 15 were involved in kinship relationships of varying degrees, including 3 parent-offspring relationships. All observed parent-offspring pairs were mother and son. In addition to the absence of biological daughters, we observed a number of young women and girls with no biological relatives in our sample. These observations, together with the high mitochondrial diversity in our sample, are consistent with the practice of female exogamy in the population served by Mokrin. However, moderate-to-high Y-chromosomal diversity suggests a degree of male mobility greater than that expected under strict patrilocality. Individual status differences at Mokrin, as indicated by grave goods, support the inference that females could inherit status, but could not transmit status to all their sons. The case of a son whose grave good richness outstrips that of his biological mother suggests that sons had the possibility to acquire status during their lifetimes. The Mokrin sample resembles a genetically unstructured population, suggesting that the communitys social hierarchies were not accompanied by strict marriage barriers.

genomics↗

bioRxiv2020

Potent neutralizing antibodies from COVID-19 patients define multiple targets of vulnerability

The rapid spread of SARS-CoV-2 has a significant impact on global health, travel and economy. Therefore, preventative and therapeutic measures are urgently needed. Here, we isolated neutralizing antibodies from convalescent COVID-19 patients using a SARS-CoV-2 stabilized prefusion spike protein. Several of these antibodies were able to potently inhibit live SARS-CoV-2 infection at concentrations as low as 0.007 {micro}g/mL, making them the most potent human SARS-CoV-2 antibodies described to date. Mapping studies revealed that the SARS-CoV-2 spike protein contained multiple distinct antigenic sites, including several receptor-binding domain (RBD) epitopes as well as previously undefined non-RBD epitopes. In addition to providing guidance for vaccine design, these mAbs are promising candidates for treatment and prevention of COVID-19.

microbiology↗

bioRxiv2020

The architecture of protein synthesis in the developing neocortex at near-atomic resolution reveals Ebp1-mediated neuronal proteostasis at the 60S tunnel exit

Protein synthesis must be finely tuned in the nervous system, as it represents an essential feature of neurodevelopmental gene expression, and dominant pathology in neurological disease. However, the architecture of ribosomal complexes in the developing mammalian brain has not been analyzed at high resolution. This study investigates the architecture of ribosomes ex vivo from the embryonic and perinatal mouse neocortex, revealing Ebp1 as a 60S peptide tunnel exit binding factor at near-atomic resolution by multiparticle cryo-electron microscopy. The impact of Ebp1 on the neuronal proteome was analyzed by pSILAC and BONCAT coupled mass spectrometry, implicating Ebp1 in neurite outgrowth proteostasis, with in vivo embryonic Ebp1 knockdown resulting in dysregulation of neurite outgrowth. Our findings reveal Ebp1 as a central component of neocortical protein synthesis, and the 60S peptide tunnel exit as a focal point of gene expression control in the molecular specification of neuronal morphology. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/939488v1_ufig1.gif" ALT="Figure 1"> View larger version (59K): org.highwire.dtl.DTLVardef@1231351org.highwire.dtl.DTLVardef@1c940f7org.highwire.dtl.DTLVardef@1c81e2corg.highwire.dtl.DTLVardef@135008b_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2020

Melon ethylene-mediated transcriptome and methylome dynamics provide insights to volatile production

During climacteric ripening large-scale transcriptional modifications are governed by ethylene. While ripening-related chromatin modifications are also known to occur, a direct connection between these factors has not been demonstrated. We characterized ethylene-mediated transcriptome modification, genome methylation dynamics, and their relation to organoleptic modifications during fruit ripening in the climacteric melon and an ethylene repressed line where the fruit-specific ACC oxidase 1 (ACO1) gene was targeted by antisense. The ACO1 antisense line exhibited mainly reduced transcriptional repression of ripening-related genes associated with DNA CHH hypomethylation at the onset of ripening. Additionally, transcription of a small set of ethylene-induced genes, including known ripening-associated genes, was inhibited by ACO1 repression and this inhibition was associated with CG hypermethylation. In the ACO1 antisense line, the accumulation of aromatic compounds, which are mainly derived from the catabolism of amino acids, is known to be inhibited. One of the ethylene-mediated transcriptionally up-regulated genes, CmTHA1, encoding a threonine aldolase, exhibited differential cytosine methylation. Threonine aldolase catalyzes the conversion of L-threonine/L-allo threonine to glycine and acetaldehyde and thus is likely involved in threonine-dependent ethyl ester biosynthesis. Yeast mutant complementation and incubation of melon discs with labeled threonine verified CmTHA1 threonine aldolase activity, revealing an additional ethylene-dependent amino acid catabolism branch involved in climacteric melon ripening.

plant biology↗

bioRxiv2019

SLC2A knockout mice deficient in ascorbic acid synthesis recapitulate aspects of arterial tortuosity syndrome and display mitochondrial respiration defects

Arterial tortuosity syndrome (ATS) is a recessively inherited connective tissue disorder, mainly characterized by tortuosity and aneurysm formation of the major arteries. ATS is caused by loss-of-function mutations in SLC2A10, encoding the facilitative glucose transporter GLUT10. Former studies implicate GLUT10 in transport of dehydroascorbic acid, the oxidized form of ascorbic acid (AA). Mouse models carrying homozygous Slc2a10 missense mutations do not recapitulate the human phenotype. Since mice, in contrast to humans, are able to intracellularly synthesize AA, we generated a novel ATS mouse model, deficient for Slc2a10 as well as Gulo, which encodes for L-gulonolactone oxidase, an enzyme catalyzing the final step in AA biosynthesis in rodents. Gulo;Slc2a10 knock-out mice show mild phenotypic anomalies, which were absent in single knock-out controls. While Gulo;Slc2a10 knock-out mice do not fully phenocopy human ATS, histological and immunocytochemical analysis revealed compromised extracellular matrix formation. TGF{beta} signaling remained unaltered, while mitochondrial function was compromised in smooth muscle cells derived from Gulo;Slc2a10 knock-out mice. Altogether, our data add evidence that ATS is an ascorbate compartmentalization disorder, but additional factors underlying the observed phenotype in humans remain to be determined.

genetics↗