Biology subjects

Ferrante, F.

Publications and source records attributed to Ferrante, F..

6 recordsLinked to original sources

bioRxiv2024

Unravelling the microplastic menace: different polymers work in synergy to increase bee vulnerability

Microplastics (MPs) are growing and ubiquitous environmental pollutants and represent one of the greatest contemporary challenges caused by human activities. Current research has predominantly examined the singular toxicological effects of individual polymers, neglecting the prevailing reality of organisms confronted with complex contaminant mixtures and potential synergistic effects. To fill this research gap, we investigated the lethal and sublethal effects of two common MPs, polystyrene (PS - 4.8-5.8 m) and poly(methyl methacrylate) (PMMA - 1-40 m), and their combination (MIX), on the pollinating insect Apis mellifera. For each treatment, we evaluated the oral toxicity of two ecologically relevant and one higher concentration (0.5, 5 and 50 mg/L) and analysed their effects on the immune system and worker survival. As immune activation can alter the cuticular hydrocarbon profile of honey bees, we used gas chromatography-mass spectrometry (GC-MS) to investigate whether MPs lead to changes in the chemical profile of foragers and behavioural assay to test whether such changes affect behavioural patterns of social recognition, undermining overall colony integrity. The results indicate a synergistic negative effect of PS and PMMA on bee survival and immune response, even at ecologically relevant concentrations. Furthermore, alterations in cuticle profiles were observed with both MPs at the highest and intermediate concentrations, with PMMA being mainly responsible. Both MPs exposure resulted in a reduction in the abundance of several cuticular compounds. Hive entry guards did not show increased inspection or aggressive behaviour towards exposed foragers, allowing them to enter the colony without being treated differently from uncontaminated foragers. These findings raise concerns not only for the health of individual bees, but also for the entire colony, which could be at risk if contaminated nestmates enter the colony undetected, allowing MPs to spread throughout the hive.

animal behavior and cognition↗

bioRxiv2023

In vivo binding free energy landscape reveals kinetic control of transcription factor function

Transcription factors (TFs) such as the central DNA-binding hub in Notch signal transduction, RBPJ, bind to specific DNA sequences to regulate gene transcription. How the efficiency of gene regulation depends on the TF-DNA binding kinetics and cofactor interactions is mostly unknown. We determined the DNA binding kinetics and the transcriptional activity of RBPJ and several mutant variants by live-cell single-molecule tracking and reporter assays, and measured their genome-wide chromatin occupation by ChIP-Seq. We observed that cofactor binding, in addition to DNA binding, was required for target site specificity. Importantly, the target site search time of RBPJ was longer than its residence time, indicating kinetic rather than thermodynamic binding stability. Impaired DNA binding, e.g. by mutation K195E related to Adams-Oliver-Syndrome, modulated not only dissociation, but also association to target sites. Impaired cofactor binding mainly altered the rates of unspecific binding and target site association. For other TFs, we also observed longer search than residence times, indicating that kinetic rather than thermodynamic stability of DNA binding might be a general feature of TFs in vivo. We propose that an effective in vivo binding energy landscape of TF-DNA interactions constitutes an instructive visualization of TF-DNA binding kinetics and the changes upon mutations.

biophysics↗

bioRxiv2023

Comprehensive Genomic Features indicative for Notch Responsiveness

Transcriptional specificity is often determined by transcription factor levels and/or chromatin context. In the Notch signal transduction pathway, transcription factor RBPJ is the central component and directly forms a coactivator complex together with the Notch intracellular domain (NICD). While the RBPJ protein levels remain constant in most tissues, dynamic expression of Notch target genes varies depending on the given cell-type and the Notch activity state. To elucidate dynamic RBPJ binding genome-wide, we investigated RBPJ occupancy by ChIP-Seq making use of Notch-dependent T cells. Surprisingly, only a small set of the total RBPJ sites show a dynamic binding behavior in response to Notch signaling. Compared to static RBPJ sites, dynamic sites differ in regard to their chromatin state, binding strength and enhancer positioning. Dynamic RBPJ sites are predominantly located distal to transcriptional start sites (TSS), while most static sites are found in promoter-proximal regions. Importantly, gene responsiveness is preferentially associated with dynamic RBPJ binding sites and this static and dynamic binding behavior is repeatedly observed in different cell types and species. Based on the above findings we used a machine-learning algorithm to predict Notch responsiveness with high confidence in different cellular contexts. This approach is potentially applicable to other transcription factors regulating signal-induced gene sets. Our results strongly support the notion that the combination of binding strength and enhancer positioning are indicative of Notch responsiveness.

genomics↗

bioRxiv2023

Microplastics reach the brain and interfere with honey bee cognition

Scientific research exploring the impact of microplastics (MPs) in terrestrial systems is still at an early stage but has already confirmed that exposure to plastics leads to various detrimental health effects in several organisms. Although recent studies have shown the toxicological effects of single MP polymers on honey bees, the effects of different polymer combinations and their consequences on cognitive and behavioural performance remain unknown. To fill this knowledge gap, we investigated the effects of MPs, both individually and in combination, on the cognitive abilities of the honey bee Apis mellifera. We evaluated the acute oral toxicity of Polystyrene (PS) and Plexiglass (PMMA) MPs, as well as a combination of the two (MIX), at three different concentrations (0.5, 5 and 50 mg/L-1) and analysed their effects on sucrose responsiveness and appetitive olfactory learning and memory. We also explored whether these MPs could reach and accumulate in the insect brain using Two-Photon Fluorescence Microscopy (TPFM) in combination with an optimized version of the DISCO clearing technique. The results revealed that PS reduced the responsiveness of foragers to sucrose, whereas PMMA had no significant impact; however, the combination of PMMA and PS had a pronounced negative effect on sucrose responsiveness. In addition, both PMMA and PS, as well as MIX, impaired bee learning formation and memory retrieval, with PS exhibiting the most severe effects. Regarding our brain imaging analysis performed with TFPM, we found that after only three days of oral exposure, MPs could penetrate and accumulate in the brain. These results raise concerns about the potential mechanical, cellular, and biochemical damage that MPs may cause to the central nervous system.

animal behavior and cognition↗

bioRxiv2023

Separate attentional processes in the two visual systems of jumping spiders

1By selectively focusing on a specific portion of the environment, animals can solve the problem of information overload, toning down irrelevant inputs and concentrate only on the relevant ones. This may be of particular relevance for animals such as the jumping spider, which possess a wide visual field of almost 360{degrees} and thus could benefit from a low-cost system for sharpening attention. Jumping spiders have a modular visual system composed of four pairs of eyes, of which only the two frontal eyes (i.e., AMEs) are motile, whereas the other secondary pairs remain immobile. We hypothesized that jumping spiders can exploit both primary and secondary eyes for stimulus detection and attentional shift, with the two systems working synergistically. In Experiment 1 we investigated AMEs attentional responses following a spatial cue presented to the secondary eyes. In Experiment 2, we tested for enhanced attention in the secondary eyes visual field congruent with the direction of the AMEs focus. In both experiments, we observed that animals were faster and more accurate in detecting a target when it appeared in a direction opposite to that of the initial cue. In contrast with our initial hypothesis, these results would suggest that attention is segregated across eyes, while each system works to compensate the other by attending to different spatial locations, rather than sharing a common attentional focus.

animal behavior and cognition↗

bioRxiv2022

The structure, binding, and function of a Notch transcription complex involving RBPJ and the epigenetic reader protein L3MBTL3

The highly conserved Notch pathway transmits signals between neighboring cells to elicit distinct downstream transcriptional programs. In given contexts, Notch is a major regulator of cell fate specification, proliferation, and apoptosis, such that aberrant Notch signaling leads to a pleiotropy of human diseases, including developmental disorders and cancers. The canonical pathway signals through the transcription factor CSL (RBPJ in mammals), which forms a transcriptional activation complex with the intracellular domain of the Notch receptor and the coactivator Mastermind. CSL can also function as a transcriptional repressor by forming complexes with one of several different corepressor proteins, such as FHL1 or SHARP in mammals and Hairless in Drosophila. Recently, we identified the malignant brain tumor (MBT) family member L3MBTL3 as a bona fide RBPJ binding corepressor that recruits the repressive lysine demethylase LSD1/KDM1A to Notch target genes. Here we define the RBPJ-interacting domain (RBP-ID) of L3MBTL3 and report the 2.06 [A] crystal structure of the complex formed between RBPJ, the RBP-ID of L3MBTL3 and DNA. The structure reveals the molecular interactions underlying L3MBTL3 complexation with RBPJ, which we comprehensively analyze with a series of L3MBTL3 and RBPJ mutations that span the binding interface. Compared to other RBPJ-binding proteins, we find that L3MBTL3 interacts with RBPJ via an unusual binding motif, which is sensitive to mutations throughout its RBPJ-interacting region. We also show that these disruptive mutations affect RBPJ and L3MBTL3 function in cells, providing further insights into Notch mediated transcriptional regulation.

biochemistry↗