Biology subjects

Pasquini, E.

Publications and source records attributed to Pasquini, E..

5 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↗

bioRxiv2024

Noxious stimulation induces self-protective behaviour in bumblebees

Self-grooming directed towards a noxiously-stimulated body part is one indicator that an animal may feel pain. In insects, the lack of evidence for such behaviour has been widely argued to reflect the absence of pain experiences. Here, we tested whether bumblebees (Bombus terrestris) selectively groom one of their antennae that was touched with a noxiously-heated (65 {square}C) probe. In the first two minutes after being touched with the noxiously-heated probe, bees groomed their touched antenna a) more than their untouched antenna, b) more than bees that were touched on the antenna with an unheated probe, and c) more than control (untouched) bees groomed either of their antennae. Our results clearly show that bumblebees can direct grooming towards a site of noxious stimulation. Our findings thus refute arguments that claim that insects do not feel pain because of their lack of displaying this behaviour.

animal behavior and cognition↗

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

Mitochondrial DNA released by senescent cells triggers immunosuppression in cancer

DNA is a potent damage-associated molecular pattern signaling that, once in the extracellular space, triggers the activation of the innate immune system. Here we find that senescent cells release mtDNA to both the cytosol and the extracellular space. In cells undergoing cellular senescence, the release of mtDNA precedes that of nuclear DNA resulting in the activation of the cGAS/STING pathway and establishment of cellular senescence. Intriguingly, by exploiting co-culture and in vivo cross-species experiments, we show that extracellular mtDNA released by senescent tumors cells is specifically captured by polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) in the tumor microenvironment (TME). Mechanistically we find that PMN-MDSCs uptake mtDNA to enhance their immunosuppressive ability. Pharmacological inhibition of mtDNA released from senescent tumor cells blocks the PMN-MDSCs immunosuppressive activity, improving the efficacy of therapy-induced senescence (TIS) in cancer. These results reveal the crucial role of mtDNA in initiating cellular senescence and immunosuppression independently of the SASP. Thus, targeting mtDNA release-mediated pathway may hold promise to reprogram the immune suppressive microenvironment in patients treated with chemotherapy.

cell biology↗

bioRxiv2020

Nectar non-protein amino acids (NPAAs) do not change nectar palatability but enhance learning and memory in honey bees

Floral nectar is a pivotal element of the intimate relationship between plants and pollinators and its chemical composition is likely to have been shaped by strong selective pressures. Nectars are composed of a plethora of nutritionally valuable compounds but also hundreds of secondary metabolites (SMs) whose ecological role is still not completely understood. Here we performed a set of behavioural experiments to study whether five ubiquitous nectar non-protein amino acids (NPAAs: {beta}-alanine, GABA, citrulline, ornithine and taurine) interact with gustation, feeding preference, and learning and memory in the pollinator Apis mellifera. We showed that harnessed foragers were unable to discriminate NPAAs from water when only accessing antennal chemo-tactile information and that freely moving bees did not exhibit innate feeding preferences for NPAA-laced sucrose solutions. Also, dietary consumption of NPAAs did not alter food consumption or longevity in caged bees over 10 days. Taken together our data suggest that ecologically relevant concentrations of NPAAs did not alter nectar palatability to bees. Olfactory conditioning assays showed that honey bees were more likely to learn a scent when it signalled a sucrose reward containing either {beta}-alanine or GABA, and that GABA also enhanced specific memory retention. Conversely, when ingested two hours prior to conditioning, GABA, {beta}-alanine, and taurine weakened bees acquisition performances but not specific memory retention, which was enhanced in the case of {beta}-alanine and taurine. Neither citrulline nor ornithine affected learning and memory. Our study suggests that NPAAs in nectars may represent a cooperative strategy adopted by plants to attract beneficial pollinators, while simultaneously enhancing pollen transfer among conspecific flowers. Future work should validate these results in more ecological scenarios and extend the study to as many nectar SMs as possible, alone and in combination, as well as to other species of pollinators.

animal behavior and cognition↗