Biology subjects

Schwarz, S.

Publications and source records attributed to Schwarz, S..

At least 19 recordsLinked to original sources

bioRxiv2025

Phylodynamics and genome-wide association studies reveal the expansion of modern Streptococcus canis in Germany

Streptoccocus canis is a leading canine pathogen causing 22.4% of canine streptococcal infections. However, knowledge of factors contributing to S. canis expansion is limited. This study uses population genetics to structure a S. canis dataset of 585 isolates and identify genetic markers contributing to the success of each dominant lineage. The dataset is composed of canine, feline and bovine isolates primarily from Germany collected between the years 1996 and 2021. We performed Multi-Locus Sequence Typing (MLST) for an initial analysis and clustered the population with fastBAPS based on the whole genome. Dated phylogenies were inferred with BEAST and Genome-Wide Association Studies (GWAS) were conducted with Scoary. MLST showed that in Germany there are two dominant groups of canine S. canis, ST43 (n= 75) and ST9 (n= 51), which were grouped into BAPS-6 and BAPS-5, respectively. The BAPS-6 cluster emerged as early as 1988 with major expansion starting around 2010. We showed via GWAS that this cluster is associated with a putative Streptococcus anginosus derived integrative and conjugative element carrying a putative cysteine protease. Furthermore, the BAPS-5 cluster emerged around 1786 with a bovine/feline subcluster appearing around 1879. This subcluster is associated with a variant of the streptococcal lac operon, which appears to have resulted from an exchange with Streptococcus dysgalactiae. We present the largest population genetics study to date for S. canis where we show that its expansion is associated with genetic exchange with other streptococcal species leading to increased pathogenic potential (BAPS-6) or host adaptation (BAPS-5). ImportanceStreptococcus canis is a bacterium which poses considerable threat to the health of dogs through superficial infections. Current research could benefit from understanding the reasons for its expansion and spread into other hosts. We looked at the genomes of 585 S. canis isolates collected during a 25-year period and identified which parts of the population were the most successful. With powerful statistical methods, we found that two groups of S. canis were the most effective: a canine group which had become more pathogenic by acquiring DNA from Streptococcus anginosus, and another group which spread from dogs into cats and cows by acquiring genetic material for lactose consumption from Streptococcus dysgalactiae. For the first time, we link the expansion of major S. canis groups to genetic exchange events with closely related streptococcal species to understand S. canis evolution and spread.

microbiology↗

bioRxiv2025

Detection of vasculogenic mimicry in equine ocular, oronasal, and genital squamous cell carcinoma

Squamous cell carcinoma (SCC) is the most common malignant tumor disease in horses. It predominantly affects the ocular, oronasal, and anogenital region. Equine SCC is difficult to treat, also because important aspects of SCC development and metastasis are still unclear. We previously provided evidence that equine SCC cells can adopt a stem cell-like phenotype as a hallmark of malignant progression. Here, we investigated whether equine SCCs harbor endothelial-like tumor cells that form an alternative network of pseudo-vessels better known as vasculogenic mimicry (VM). Following histopathological diagnosis, 43 equine SCCs or precursor lesions (15 ocular, 14 genital, 14 oronasal tumors) were PCR-screened for equine papillomavirus (EcPV) infection. Subsequently, formalin-fixed paraffin-embedded-sections of all tumors were analyzed by Periodic Acid-Schiff (PAS) reaction and immunohistochemical (IHC) staining for endothelial cell marker CD31. Obtained micrographs were evaluated by a scientific board to unanimously identify sections of intact tumor tissue displaying PAS-positive, CD31-negative lumens harboring erythrocytes. Thirteen lesions exhibiting these features were subjected to triple immunofluorescence (IF) staining for CD31, pan-cytokeratin (KRT) and type 4 collagen (Col4) or alpha smooth muscle actin (SMA) to confirm the presence of VM, and to determine whether pericytes have a role in this phenomenon. All genital and 50% of oronasal lesions scored positive for EcPV type 2, whilst ocular lesions tested negative. One mandibular SCC harbored EcPV type 5. Six genital, three oronasal, and four ocular tumors unambiguously exhibited VM as revealed by CD31-/PAS+ vessel-like structures containing erythrocytes, the detection of CD31-negative cells lining their lumens, and the presence of Col4 and SMA in this lining. Detection of these two proteins in the context of VM suggests that VM-forming cancer cells recruit pericytes to enhance channel formation and stability. To our knowledge, this is the first report providing evidence of VM in equine cancer, and more generally, SCC in animals.

cancer biology↗

bioRxiv2025

Restoration of Susceptibility of blaNDM-bearing Escherichia. coli to Carbapenem Antibiotics by Exogenous N-acetylcysteine

The global spread of the New Delhi metallo-{beta}-lactamase (NDM) -producing carbapenem-resistant Enterobacteriaceae pose a serious threat to public health, as NDM and its variants enzymes efficiently hydrolyze almost {beta}-lactam antibiotics. The development of novel antibiotics or antibiotic adjuvants capable of eradicating antibiotic-resistance bacteria through multiple mechanisms represents a promising strategy for reversing antibiotic resistance and preventing the emergence of new resistance. In this study, we utilized high-performance liquid chromatography (HPLC) to demonstrate that N-acetylcysteine (NAC) is a prominent reducing metabolite in bacteria harboring NDM-5. Notably, NAC was able to restore carbapenem susceptibility in NDM-producing bacteria in vitro. Subsequently, we further investigated the underlying mechanisms involved. Our findings revealed that NAC exerts its effect through multiple mechanisms that collectively contribute to reversing meropenem resistance. Firstly, NAC may inhibit biofilm formation and reduces polysaccharide production in NDM-positive Escherichia coli. and this potential mechanism was verified by transcriptomic analysis, reverse transcription PCR (RT-PCR) and a biofilm restoration experiment involving the addition of citrate cycle intermediate metabolites. Secondly, RT-PCR analysis demonstrated that NAC significantly downregulates the expression of blaNDM-5. Additionally, NAC exhibited competitive inhibition of NDM activity in vitro. Thirdly, NAC was found to enhance the intracellular accumulation of meropenem, therapy increasing its bactericidal efficacy. These three independent mechanisms offer valuable insights for developing adjuvants. The discovery offers a promising prospect for combating the antibiotic resistance concern. This study paves the way for further exploration and potential clinical applications in the fight against antibiotic-resistant bacterial infections.

pharmacology and toxicology↗

bioRxiv2024

Latent learning without map-like representation of space in navigating ants

Desert ants are excellent navigators. Each individual learns long foraging routes meandering between the trees and bushes in their natural habitat. It is well-known how the insect brain memorizes and recognizes views, and how this recognition can guide their way. However, little is known about the rule that guide spatial learning in the first place. Here we recorded the paths of desert ants navigating in their natural habitat under various displacement conditions. We demonstrate that ants learn continuously the routes they travel and memorize them in one trial, without the need for reward or punishment, and even if these routes are meandering and do not lead to places of interest: a concept called latent learning, which is typically associated with the formation of map-like representation in vertebrates. Yet, the failure of ants to solve simple artificial navigation tasks -even with the goal being clearly visible- reveals that they relied on egocentric visual memories without map-like representation of the surrounding space. Our results unveil the rules governing the formation and recall of latent memories. A model shows that it can be implemented in the insects Mushroom bodies brain area through dynamic interactions between short- and long-lasting memories.

animal behavior and cognition↗

bioRxiv2024

Is this scenery worth exploring? Insight into the visual encoding of navigating ants.

Solitary foraging insects like desert ants rely heavily on vision for navigation. While ants can learn visual scenes, it is unclear what cues they use to decide if a scene is worth exploring at the first place. To investigate this, we recorded the motor behavior of Cataglyphis velox ants navigating in a virtual reality set-up and measured their lateral oscillations in response to various unfamiliar visual scenes under both closed-loop and open-loop conditions. In naturalistic-looking panorama, ants display regular oscillations as observed outdoors, allowing them to efficiently scan the scenery. Manipulations of the virtual environment revealed distinct functions served by dynamic and static cues. Dynamic cues, mainly rotational optic flow, regulated the amplitude of oscillations but not their regularity. Conversely, static cues had little impact on the amplitude but were essential for producing regular oscillations. Regularity of oscillations decreased in scenes with only horizontal, only vertical or no edges but was restored in scenes with both edge types together. The actual number of edges, the visual pattern heterogeneity across azimuths, the light intensity or the relative elevation of brighter regions did not affect oscillations. We conclude that ants use a simple but functional heuristic to determine if the visual world is worth exploring, relying on the presence of at least two different edge orientations in the scene. Summary statementUsing a virtual reality setup, we reveal that ants rely on a heuristic to trigger visual exploration in an unfamiliar scene. The simultaneous presence of vertical and horizontal edges is necessary and sufficient for the ants to produce lateral oscillations and scan the scene.

animal behavior and cognition↗

bioRxiv2024

Conformational dynamics of electrostatically charged Intrinsically Disordered Proteins

We experimentally and computationally study the dynamics of homogeneously electrically charged intrinsically disordered proteins (IDPs) in ionic solutions (aqueous solutions containing salt). Computationally, this is achieved by extending a recently introduced discrete elastic rod (DER) model to include electrostatic interactions. The respective model includes only three free parameters: bending stiffness, bond length, and hydrodynamic radius. These parameters were obtained by fitting the measured conformational dynamics of uncharged polypeptides as reported in a previous publication [8]. We compare our computational results with photo-electron transfer fluorescence correlation spectroscopy (PET-FCS) measurements of the conformational dynamics of the highly charged (-44 e-) intrinsically disordered protein Prothymosin . We here report on an agreement between the loop-closing rates obtained from our computational model and the respective experimental measurements, with rate values significantly slower than those observed for uncharged IDPs.

biophysics↗

bioRxiv2024

Peptide-stimulation of autologous T cells reverts immune checkpoint inhibitor resistance of hypermutated colorectal cancer cells

Two hypermutated colon cancer cases with patient-derived cell lines, peripheral and tumor-infiltrating T cells available were selected for detailed investigation of immunological response. T cells co-cultured with autologous tumor cells showed only low levels of pro-inflammatory cytokines and failed at tumor recognition. Similarly, treatment of co-cultures with immune checkpoint inhibitors (ICI) did not boost antitumor immune responses. Since proteinase inhibitor 9 (PI-9) was detected in tumor cells, a specific inhibitor (PI-9i) was used in addition to ICI in T cell cytotoxicity testing. However, only pre-stimulation with tumor-specific peptides (cryptic and neoantigenic) significantly increased recognition and elimination of tumor cells by T cells independently of ICI or PI-9i. We showed, that ICI resistant tumor cells can be targeted by tumor-primed T cells and also demonstrated the superiority of tumor-naive peripheral blood T cells compared to highly exhausted tumor-infiltrating T cells. Future precision immunotherapeutic approaches should include multimodal strategies to successfully induce durable anti-tumor immune responses.

cancer biology↗

bioRxiv2024

Kinases in motion: impact of protein and small molecule interactions on kinase conformations

Protein kinases act as central molecular switches in the control of cellular functions. Alterations in the regulation and function of protein kinases may provoke diseases including cancer. In this study we investigate the conformational states of such disease-associated kinases using the high sensitivity of the Kinase Conformation (KinCon)-reporter system. We [fi]rst track BRAF-kinase activity conformation changes upon melanoma drug binding. Second, we also use the KinCon reporter technology to examine the impact of regulatory protein interactions on LKB1-kinase tumor suppressor functions. Third, we explore the conformational dynamics of RIP-kinases in response to TNF-pathway activation and small molecule interactions. Finally, we show that CDK4/6 interactions with regulatory proteins alter conformations which remain unaffected in the presence of clinically applied inhibitors. Apart from its predictive value, the KinCon technology helps to identify cellular factors that impact drug efficacies. The understanding of the structural dynamics of full-length protein kinases when interacting with small molecule inhibitors or regulatory proteins is crucial for designing more effective therapeutic strategies.

biochemistry↗

bioRxiv2023

Compensation to visual impairments and behavioral plasticity in navigating ants

Desert ants are known to rely heavily on vision while venturing for food and returning to the nest. During these foraging trips, ants memorize and recognize their visual surroundings, which enables them to recapitulate individually learnt routes in a fast and effective manner. The compound eyes are crucial for such visual navigation; however, it remains unclear how information from both eyes are integrated and how ants cope with visual impairment. Here we manipulated the ants visual system by covering one of the two compound eyes and analyzed their ability to recognize familiar views in various situations. Monocular ants showed an immediate disruption of their ability to recapitulate their familiar route. However, they were able to compensate for the visual impairment in a few hours by restarting a route-learning ontogeny, as naive ants do. This re-learning process with one eye forms novel memories, without erasing the previous memories acquired with two eyes. Additionally, ants having learnt a route with one eye only are unable to recognize it with two eyes, even though more information is available. Together, this shows that visual memories are encoded and recalled in an egocentric and fundamentally binocular way, where the visual input as a whole must be matched to enable recognition. We show how this kind of visual processing fits with their neural circuitry. Significance StatementIf humans look at the world with both eyes, they have no problem to then recognize it with one eye only, and vice-versa. Thus, our way of encoding the world is robust to changes of the visual field. Yet ants do so very differently. Views learnt with two eyes can only be recognized with two eyes, and views learnt with one eye can only be recognized with one eyes (the same eye). However, this rigidity is compensated by a remarkable behavioral flexibility. Upon covering one eye, ants - which can no longer recognize their familiar surroundings - will restart a learning process to store these novel visual inputs in a parallel memory and resume their normal foraging activity.

animal behavior and cognition↗

bioRxiv2022

Rescue of the increased susceptibility to Mild Chronic Oxidative Stress of iNeurons carrying the MAPT Chromosome 17q21.3 H1/H1 risk allele by FDA-approved compounds

The microtubule associated protein tau (MAPT) chromosome 17q21.31 locus lies within a region of high linkage disequilibrium (LD) conferring two extended haplotypes commonly referred to as H1 and H2. The major haplotype, H1 has been genetically associated with an increased risk for multiple neurodegenerative disorders, including Progressive Supranuclear Palsy (PSP), Corticobasal Degeneration (CBD), APOE {varepsilon}4-negative Alzheimers disease (AD) and Parkinsons disease (PD). The mechanism causing this increased risk is largely unknown. Here, we investigated the role of Mild Chronic Oxidative Stress (MCOS) in neurogenin 2 (NGN2) induced neurons (iNeurons) derived from iPS (induced pluripotent stem cells) from carriers of both haplotypes. We identified that iNeurons of the H1 homozygous haplotype showed an increased susceptibility to MCOS compared to homozygous H2 carriers, leading to cell death through ferroptosis. We performed a cellular screen in H1 iNeurons using a FDA-approved Drug Library and identified candidate molecules that rescued the increased susceptibility to MCOS and prevented ferroptosis in H1 iNeurons. HighlightsO_LIMild Chronic Oxidative Stress induces neurotoxicity via ferroptosis on iNGN2 neurons C_LIO_LIAxonal degeneration, disordered microtubules, blebs precede neurotoxicity C_LIO_LIMAPT-17q21.3 locus H1/H1, risk allele for NDD is more vulnerable to MCOS C_LIO_LIFDA-approved drugs reverse MCOS induced ferroptosis on H1/H1 risk allele C_LI O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=158 SRC="FIGDIR/small/515284v1_ufig1.gif" ALT="Figure 1"> View larger version (43K): org.highwire.dtl.DTLVardef@eddb2eorg.highwire.dtl.DTLVardef@1d0c00dorg.highwire.dtl.DTLVardef@1f0b00eorg.highwire.dtl.DTLVardef@b68f1b_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2022

An intrinsic oscillator underlies visual navigation in ants.

Controlling behavior implies a constant balance between exploration - to gather information - and exploitation - to use this information to reach ones goal. However, how this tradeoff is achieved in navigating animals is unclear. Here we recorded the paths of two phylogenetically distant visually navigating ant species (Myrmecia croslandi and Iridomyrmex purpureus) using a trackball-treadmill directly in their habitat. We show that both species continuously produce regular lateral oscillations with bursts of forward movement when facing the general direction of travel, providing a remarkable tradeoff between visual exploration across directions and movement areas. This dynamical signature is conserved across navigational contexts but requires certain visual cues to be fully expressed. Rotational feedback regulates the extent of turns, but is not required to produce them, indicating that oscillations are generated intrinsically. Learnt visual information modulates the oscillations amplitudes to fit the task at hand in a continuous manner: an unfamiliar panorama enhances the amplitude of oscillations in both naive and experienced ants, favoring visual exploration; while a learnt familiar panorama reduces them, favoring exploitation through. The observed dynamical signature readily emerges from a simple neural-circuit model of the insects conserved pre-motor area known as the lateral accessory lobe, endorsing oscillations as a core, ancestral way of moving in insects. We discuss the importance and evolution of self-generated behaviors and how such an oscillator has been exapted to various modalities, behaviors and way of moving.

animal behavior and cognition↗

bioRxiv2022

Genome-wide association reveals host-specific genomic traits in Escherichia coli

Escherichia coli is an opportunistic pathogen that can colonize or infect various host species. There is a significant gap in our understanding to what extent genetic lineages of E. coli are adapted or restricted to specific hosts. In addition, genomic determinants underlying such host specificity are unknown.By analyzing a randomly sampled collection of 1198 whole-genome sequenced E. coli isolates from four countries (Germany, UK, Spain, and Vietnam), obtained from five host species (human, pig, cattle, chicken, and wild boar) over 16 years, from both healthy and diseased hosts, we demonstrate that certain lineages of E. coli are frequently detected in specific hosts. We report a novel nan gene cluster, designated nan-9, putatively encoding acetylesterases and determinants of uptake and metabolism of sialic acid, to be associated with the human host as identified through genome wide association studies. In silico characterization predicts nan-9 to be involved in sialic acid (Sia) metabolism. In vitro growth experiments with a representative {Delta}nan E. coli mutant strain, using sialic acids 5-N-acetyl neuraminic acid (Neu5Ac) and N-glycolyl neuraminic acid (Neu5Gc) as the sole carbon source, indicate an impaired growth behaviour compared to the wild-type. In addition, we identified several additional E. coli genes that are potentially associated with adaptation to human, cattle and chicken hosts, but not for the pig host. Collectively, this study provides an extensive overview of genetic determinants which may mediate host specificity in E. coli. Our findings should inform risk analysis and epidemiological monitoring of (antimicrobial resistant) E. coli.

genomics↗

bioRxiv2021

Aversive View Memory and Navigational Risk Sensitivity in the Desert Ant, Cataglyphis Velox

Many ants establish foraging routes through learning views of the visual panorama. Route models have focused primarily on attractive view use, which experienced foragers orient towards to return to known sites. However, aversive views have recently been uncovered as a key component of route learning. Here, Cataglyphis velox rapidly learned aversive views, when associated with a negative outcome, a period of captivity in brush, triggering an increase in hesitation behavior. These memories were based on the accumulation of experiences over multiple trips with each new experience regulating foragers hesitancy. Foragers were also sensitive to captivity time differences, suggesting they possess some mechanism to quantify duration. Finally, we analyzed foragers perception of risky (i.e. variable) versus stable aversive outcomes by associating two sites along the route with distinct captivity schedules, a fixed or variable duration, with the same mean across training. Foragers exhibited significantly less hesitation to the risky outcome compared to the fixed, indicating they perceived risky outcomes as less severe. Results align with a logarithmic relationship between captivity duration and hesitations, suggesting that aversive stimulus perception is a logarithm of its actual value. We conclude by characterizing how these behaviors can be executed within the mushroom bodies neural circuitry.

animal behavior and cognition↗

bioRxiv2021

Sequential defects in cardiac lineage commitment and maturation cause hypoplastic left heart syndrome

BackgroundComplex molecular programs in specific cell lineages govern human heart development. Hypoplastic left heart syndrome (HLHS) is the most common and severe manifestation within the spectrum of left ventricular outflow tract obstruction defects occurring in association with ventricular hypoplasia. The pathogenesis of HLHS is unknown, but hemodynamic disturbances are assumed to play a prominent role. MethodsTo identify perturbations in gene programs controlling ventricular muscle lineage development in HLHS, we performed: i) whole-exome sequencing of 87 HLHS parent-offspring trios, ii) nuclear transcriptomics of cardiomyocytes from ventricles of 4 patients with HLHS and 15 controls at different stages of heart development, iii) single cell RNA sequencing and iv) 3D modeling in iPSCs from 3 patients with HLHS and 3 controls. ResultsGene set enrichment and protein network analyses of damaging de-novo mutations and dysregulated genes from ventricles of patients with HLHS suggested alterations in specific gene programs and cellular processes critical during fetal ventricular cardiogenesis, including cell-cycle and cardiomyocyte maturation. Single-cell and 3D modeling with iPSCs demonstrated intrinsic defects in the cell-cycle/UPR/autophagy hub resulting in disrupted differentiation of early cardiac progenitor lineages leading to defective cardiomyocyte-subtype differentiation/maturation in HLHS. Additionally, premature cell-cycle exit of ventricular cardiomyocytes from HLHS patients prevented normal tissue responses to developmental signals for growth leading to multinucleation/polyploidy, accumulation of DNA damage, and exacerbated apoptosis, all potential drivers of left ventricular hypoplasia in absence of hemodynamic cues. ConclusionsOur results highlight that despite genetic heterogeneity in HLHS, many mutations converge on sequential cellular processes primarily driving cardiac myogenesis, suggesting novel therapeutic approaches.

developmental biology↗

bioRxiv2021

Synthetic cell-based materials extract positional information from morphogen gradients

Dynamic biomaterials composed of synthetic cellular structures have the potential to adapt and functionally differentiate guided by physical and chemical cues from their environment. Inspired by developing biological systems, which efficiently extract positional information from chemical morphogen gradients in the presence of environmental uncertainties, we here investigate the analogous question: how well can a synthetic cell determine its position within a synthetic multicellular structure? In order to calculate positional information in such systems, we created and analyzed a large number of replicas of synthetic cellular assemblies, which were composed of emulsion droplets connected via lipid bilayer membranes. The droplets contained cell-free two-node feedback gene circuits that responded to gradients of a genetic inducer acting as a morphogen. We found that in our system, simple anterior-posterior differentiation is possible, but positional information is limited by gene expression noise, and is also critically affected by the temporal evolution of the morphogen gradient and the life-time of the cell-free expression system contained in the synthetic cells. Using a 3D printing approach, we demonstrate morphogen-based differentiation also in larger tissue-like assemblies.

synthetic biology↗

bioRxiv2020

A lateralised design for the interaction of visual memories and heading representations in navigating ants

The navigational skills of ants, bees and wasps represent one of the most baffling examples of the powers of minuscule brains. Insects store long-term memories of the visual scenes they experience 1, and they use compass cues to build a robust representation of directions 2,3. We know reasonably well how long-term memories are formed, in a brain area called the Mushroom Bodies (MB) 4-8, as well as how heading representations are formed in another brain area called the Central Complex (CX) 9-12. However, how such memories and heading representations interact to produce powerful navigational behaviours remains unclear 7,13,14. Here we combine behavioural experiments with computational modelling that is strictly based on connectomic data to provide a new perspective on how navigation might be orchestrated in these insects. Our results reveal a lateralised design, where signals about whether to turn left or right are segregated in the left and right hemispheres, respectively. Furthermore, we show that guidance is a two-stage process: the recognition of visual memories - presumably in the MBs - does not directly drive the motor command, but instead updates a "desired heading" - presumably in the CX - which in turn is used to control guidance using celestial compass information. Overall, this circuit enables ants to recognise views independently of their body orientation, and combines terrestrial and celestial cues in a way that produces exceptionally robust navigation.

animal behavior and cognition↗

bioRxiv2020

Primate heart regeneration via migration and fibroblast repulsion by human heart progenitors

SUMMARYHuman heart regeneration is one of the most critical unmet clinical needs at a global level1. Muscular regeneration is hampered both by the limited renewing capacity of adult cardiomyocytes2-4 and the onset of cardiac fibrosis5,6, resulting in reduced compliance of the tissue. Primate have proven to be ideal models for pluripotent stem cell strategies for heart regeneration, but unravelling specific approaches to drive cell migration to the site of injury and inhibition of subsequent fibrosis have been elusive. Herein, by combining human cardiac progenitor lineage tracing and single-cell transcriptomics in injured non-human primate heart bio-mimics, we uncover the coordinated muscular regeneration of the primate heart via directed migration of human ventricular progenitors to sites of injury, subsequent fibroblast repulsion targeting fibrosis, and ultimate functional replacement of damaged cardiac muscle by differentiation and electromechanical integration. Single-cell RNAseq captured distinct modes of action, uncovering chemoattraction mediated by CXCL12/CXCR4 signalling and fibroblast repulsion regulated by SLIT2/ROBO1 guidance in organizing cytoskeletal dynamics. Moreover, transplantation of human cardiac progenitors into hypo-immunogenic CAG-LEA29Y transgenic porcine hearts following injury proved their chemotactic response and their ability to generate a remuscularized scar without the risk of arrhythmogenesis in vivo. Our study demonstrates that inherent developmental programs within cardiac progenitors are sequentially activated in the context of disease, allowing the cells to sense and counteract injury. As such, they may represent an ideal bio-therapeutic for functional heart rejuvenation.Competing Interest StatementThe authors have declared no competing interest.View Full Text

cell biology↗

bioRxiv2019

How do backward walking ants (Cataglyphis velox) cope with navigational uncertainty?

Current opinion in insect navigation assumes that animals need to align with the goal direction to recognise familiar views and approach it. Yet, ants sometimes drag heavy food items backward to the nest and it is still unclear to what extent they rely on visual memories while doing so. In this study displacement experiments and alterations of the visual scenery reveal that ants do indeed recognise and use the learnt visual scenery to guide their path while walking backward. In addition, the results show that backward homing ants estimate their directional certainty by combining visual familiarity with other cues such as their path integrator and the time spent backward. A simple model that combines path integration with repulsive and attractive visual memories captures the results.

animal behavior and cognition↗