Biology subjects

Gruber, D.

Publications and source records attributed to Gruber, D..

6 recordsLinked to original sources

bioRxiv2026

Sperm whale foraging combines persistent search with flexible prey-capture tactics

Predators searching patchy environments must coordinate movements across scales, yet this behavioural hierarchy is not yet technically possible to observe in the deep ocean. Here we show that sperm-whale foraging is organized across two nested levels: directionally persistent search paths and flexible prey-capture tactics. We combine acoustic recordings with reconstructed three-dimensional trajectories from 34 sensor-tag deployments on 20 individual whales in both the eastern Caribbean and the mid-Atlantic. Complete foraging paths exhibit heavy-tailed step lengths and superdiffusive displacement, consistent with Levy-like search. Within these paths, echolocation buzzes resolve into two recurrent acoustic-kinematic tactics. Type A involves brief ramp-ups, slower and more oscillatory movement, and longer post-buzz pauses. Type B involves prolonged ramp-ups, faster and vertically persistent movement, greater roll, slightly straighter approaches, and an energy-model estimate approximately seven times higher. Every sampled whale used both tactics and switched between them within dives, showing that the contrast is not driven by specialization among individuals. An Azorean deployment with prey-field echograms links the tactics to local prey conditions, while independent Dominica deployments recover their core kinematic contrast. Together, these results reveal a foraging hierarchy in which flexible capture actions unfold within persistent, deliberate large-scale search.

animal behavior and cognition↗

bioRxiv2025

Bad bugs, new drugs: The antimicrobial peptide C14R is active against the ESKAPE pathogens

The global rise of antimicrobial resistance among the ESKAPE pathogens represents a major challenge to public health. Here, we report the broad-spectrum antibacterial activity of the synthetic antimicrobial and pore-forming peptide C14R against all six ESKAPE species. Using a radial diffusion assay and resazurin-based viability testing, C14R exhibited potent bactericidal effect with minimum inhibitory concentrations (MICs), defined as the lowest concentration of an antimicrobial agent that completely inhibits visible growth of planktonic microorganisms, ranging from 3.4 g/mL (Enterococcus faecium, vancomycin-resistant) to 45.2 g/mL (Klebsiella quasipneumoniae, ESBL). C14R also inhibited biofilm formation by Gram-positive pathogens, with minimum biofilm inhibitory concentrations (MBICs), referring to the minimal concentration required to prevent the development of biofilms, of 15.0 g/mL (Staphylococcus aureus, MRSA) and 22.0 g/mL (E. faecium, VRE), whereas Gram-negatives biofilms showed higher tolerance. Together, these findings demonstrate that C14R retains high activity against multidrug-resistant ESKAPE strains, highlighting its potential as a lead compound for the development of next-generation antimicrobial drugs to expand the portfolio of available antibiotics and brace health systems against emerging severe infections. Author summaryAntibiotic-resistant infections are a growing threat worldwide. A small group of hospital-associated bacteria is especially problematic because they often evade multiple drugs and cause hard-to-treat infections. In this study, we tested the designed antimicrobial peptide C14R as a novel and effective way to fight these bacteria. Peptides are short protein fragments with the ability to puncture and disrupt microbial membranes. We evaluated C14R against six hospital related priority species (so called ESKAPE pathogens) and measured its ability to stop growth and to limit biofilm formation. C14R killed every species we tested and reduced biofilm of two bacteria. Our findings identify C14R as a promising lead for new treatments, particularly for difficult infections and those involving biofilms.

microbiology↗

bioRxiv2025

gFET-based aptasensors technology allows sensitive and specific quantification of the ESKAPE pathogens

The rapid rise of antimicrobial resistance among the ESKAPE pathogens, Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter spp., requires diagnostic technologies capable of fast, simplified and sensitive microbial detection. Conventional culture-based diagnostics remain too time-consuming to guide early therapeutic interventions. Here, we present a graphene field-effect transistor (gFET) aptasensor platform enabling rapid, label-free and highly sensitive quantification of all six ESKAPE pathogens. Each gFET device was functionalized with a specific DNA aptamer selected from literature sources and immobilized via a mixed pyrene-based linker strategy on reduced graphene oxide (rGO). Exposure of the functionalized sensors to logarithmically diluted bacterial suspensions (10-105 CFU mL-) produced characteristic and concentration-dependent shifts in source-drain current ({Delta}IDS). For all pathogen-specific aptamers, {Delta}IDS correlated linearly with bacterial load (R2 = 0.90-1.00), while non-target bacteria generated only low-level, unspecific fluctuations. Limits of detection ranged from 10 to 1000 bacterial cells depending on the aptamer. Together, these results demonstrate that aptamer-functionalized rGO-FETs provide a robust, scalable and highly specific electronic biosensing architecture capable of distinguishing clinically relevant multidrug-resistant pathogens with excellent analytical performance. Author summaryAntimicrobial-resistant bacteria pose a growing threat to global health, especially the so-called ESKAPE pathogens, which frequently cause hospital-acquired infections and are increasingly difficult to treat. Current diagnostic methods can take several days, delaying the start of effective therapy. In our work, we developed a fast and highly sensitive biosensor that uses electrically conductive GO and short DNA molecules, called aptamers, to recognize specific bacteria. When a pathogen binds to its matching aptamer on the sensor surface, the electrical signal of the graphene changes in a measurable way. We tested ESKAPE species and showed that all of the investigated aptamers detect only their intended bacterial targets, even at very low concentrations. Importantly, the sensors respond within minutes and do not require any labelling or complex sample preparation. Our technology demonstrates how graphene-based aptasensors can support rapid and accurate detection of dangerous bacterial pathogens and could ultimately help clinicians make faster decisions in treating infections.

microbiology↗

bioRxiv2025

The phonology of sperm whale coda vowels

In previous research, sperm whale codas (structured series of clicks used for communication) have been shown to resemble human vowels acoustically. Based on the number of formants, two different coda quality categories have been described: a-codas and i-codas. In the present paper, we demonstrate that sperm whale codas not only resemble human vowels acoustically, but also pattern like them across several dimensions. First, traditional count- and timing-based coda types interact with coda "vowel" quality (a vs. i). Second, a-codas are generally longer than i-codas. Third, the duration of i-codas has a bimodal distribution, showing a contrast between short i-codas and long[i] -codas. Fourth, the baseline coda length differs across whales. And fifth, edge clicks mismatching their coda often match an adjacent coda, a phenomenon that resembles human coarticulation. All five properties have close parallels in the phonetics and phonology of human languages. Sperm whale coda vocalizations thus represent one of the closest parallels to human phonology of any known animal communication system. SIGNIFICANCE STATEMENTSperm whales communicate using series of clicks known as codas. The codas acoustically resemble human vowels. In addition, they pattern in ways similar to human sound systems. For example, different coda types are correlated with particular click qualities, and their durations are intentionally controlled. This shows that sperm whale vocalizations are highly complex and likely constitute one of the most sophisticated communication systems in the animal kingdom. By studying it, we may be able to gain a broader understanding of animal intelligence and social behaviors, determine the impact of human activities on whale habitat, develop strategies to protect whales from threats such as noise pollution and ship traffic, and advance legislation which facilitates that protection.

animal behavior and cognition↗

bioRxiv2023

Contextual and Combinatorial Structure in Sperm Whale Vocalisations

Sperm whales (Physeter macrocephalus) are long-lived and highly social mammals that engage in complex group behaviours, including navigation, foraging, and child-rearing. During these behaviours, sperm whales communicate primarily using sequences of short bursts of clicks with varying inter-click intervals, known as codas. Past research has identified around 150 discrete coda types globally, with 21 in the Caribbean. A subset of these have been shown to encode information about caller and clan identity. However, almost everything else about the sperm whale communication system, including basic questions about its structure and information-carrying capacity, remains unknown. In this study, we show that codas exhibit contextual and combinatorial structure with key similarities to aspects of human language and other primate communication systems. First, we report previously undescribed variations in coda structure that are sensitive to the conversational context in which they occur. We call these rubato and ornamentation, by analogy to musical terminology. These variations are systematically controlled and imitated across individual whales. Second, we show that coda types are not defined by arbitrary sequences of inter-click intervals, but instead form a combinatorial coding system in which rubato and ornamentation combine with two categorical, context-independent features that we call rhythm and tempo to give rise to a large inventory of distinguishable codas. In a dataset of 8,719 codas from the sperm whales of the Eastern Caribbean clan, this sperm whale phonetic alphabet makes it possible to systematically explain observed variability in coda structure. Sperm whale vocalisations are more expressive and structured than previously believed, and are built from a repertoire comprising nearly an order of magnitude more distinguishable codas. These results show contextsensitive and combinatorial vocalisation systems extend beyond humans, and can appear in an organism with a divergent evolutionary lineage and vocal apparatus.

animal behavior and cognition↗

bioRxiv2020

Plankton Planet: 'seatizen' oceanography to assess open ocean life at the planetary scale

In every liter of seawater there are between 10 and 100 billion life forms, mostly invisible, called plankton, which form the largest and most dynamic ecosystem on our planet, at the heart of global ecological and economic processes. While physical and chemical parameters of planktonic ecosystems are fairly well measured and modelled at the planetary scale, but biological data are still scarce due to the extreme cost and relative inflexibility of the classical vessels and instruments used to explore marine biodiversity. Here we introduce Plankton Planet, an initiative whose goal is to merge the creativity of researchers, makers, and mariners to (i) develop frugal scientific instrumentation and protocols to assess the genetic and morphological diversity of plankton life, and (ii) organize their systematic deployment through fleets of volunteer sailors, fishermen, or cargo-ships to generate comparable and open-access plankton data across global and long-term spatio-temporal scales. As proof-of-concept, we show how 20 crews of sailors ("planktonauts") were abl to sample plankton biomass from the world surface ocean in a single year, generating the first citizen-based, planetary dataset of plankton biodiversity based on DNA barcodes. The quality of this dataset is comparable to that generated by Tara Oceans and is not biased by the multiplication of samplers. This dataset has unveiled significant genetic novelty and can be used to explore the taxonomic and ecological diversity of plankton at both regional and global scales. This pilot project paves the way for construction of a miniaturized, modular, evolvable, affordable and open-source citizen field-platform that will allow systematic assessment of the eco/morpho/genetic variation of aquatic ecosystems across the dimensions of the Earth system.

ecology↗