Biology subjects

Witt, M.

Publications and source records attributed to Witt, M..

5 recordsLinked to original sources

bioRxiv2025

Parrots and Humans Prefer Pitch Sequences of Intermediate Complexity

A well-established inverted U-shape relationship exists between stimulus complexity and human music preference, with preferences peaking at intermediate levels. We investigated whether preference for intermediate complexity is unique to humans or shared with other species. We compared the acoustic preferences of humans and budgerigars, known for their vocal learning and pattern recognition abilities, using a three-option place preference paradigm. Participants were presented with choices between computationally well-defined stimuli varying in complexity: pitch sequences with tones arranged either randomly (high complexity), into repeating patterns with changes (medium), or into a fully repetitive pattern (low). Our results demonstrate that both humans and budgerigars prefer stimuli with intermediate complexity, spontaneously exhibiting an inverted U-shape relationship between complexity and preference without any specific goal or external reward. Because a U-shape relationship has been argued to maximize learning, this preference may be of potential utility for vocal learning, however, further testing could determine whether it is also present for acoustic patterns in vocal non-learning species. Because vertebrates show inverted U-shape responses in a variety of non-auditory contexts, our findings may be rooted in general processes, but may depend on vocal learning to translate to acoustic contexts. This provides exciting opportunities to further investigate the fundamentals of vocal learning within and beyond the auditory and/or musical domain. Significance statementAppreciating music is part of what it means to be human, but it is unclear why. Comparing budgerigars - a vocal-learning parrot species - and humans, we focused on a sweet spot of musical enjoyment: We like to hear music thats not too complex and not too simple. Using a place preference setup, we showed that both species prefer to listen to pitch sequences with medium complexity relative to low or high complexity. This shared pattern suggests a fundamental cognitive principle that guides animals to stimuli that maximize learning, promoting vocal communication. Because both budgerigars and humans are vocal learners and music is a socially transmitted behavior, the appreciation of music thus may be rooted in the requirements of vocal learning.

animal behavior and cognition↗

bioRxiv2023

Emerging dynamic regimes and tipping points from finite empirical principles

The dynamics of biogeochemical, ecological, and astronomical systems are transient. Yet, predicting the occurrence of dynamical shifts remains a challenge due to inferential uncertainties from datasets and the limitations of asymptotic-dependent theories. To address this problem, we developed a theoretical framework that builds on the finite nature of observations. This framework assesses the relative importance of processes, defined as the mechanisms that contribute to the rate of change of the systems dynamic variables, and it predicts the critical values that would trigger a shift into a new regime. The number of observable dynamic regimes within the framework increases exponentially with the number of processes. Observers, however, only experience dynamic regimes associated with relevant processes-- those exceeding a tipping point--within their reference framework. A case study of the framework was tested for a classic predator-prey system with four processes parameterized for bacteria (prey) and lytic bacteriophages (predator). The analysis recovered the sixteen dynamic regimes predicted by the framework, including two non-trivial quasi-equilibrium dynamics. An adaptive Boolean model, which used only relevant observable processes, validated the accuracy of the framework, recovering the dynamics of the full model. The observational framework introduced here provides a strategy for identifying the processes and conditions that lead to tipping points, representing a conceptual paradigm shift in transient dynamics, placing the focus on the specific, finite context of the observer, rather than the intrinsic, asymptotic states of the system. SIGNIFICANCESudden shifts in ecological, climate, and biological systems--so-called tipping points or critical transitions--are notoriously difficult to predict. This study introduces a mathematical framework that redefines these transitions as outcomes shaped by the observers empirical limits. By accounting for finite observation time and resolution, the framework uncovers a rich spectrum of dynamic regimes that classical theories overlook. Its conceptual rigor and practical value are demonstrated in a predator-prey system. This new approach reframes how to forecast regime shifts in complex systems and offers a tool with broad relevance, from microbial ecosystems to planetary climate.

ecology↗

bioRxiv2023

Plasma Glycomic Markers of Accelerated Biological Aging During Chronic HIV Infection

People with HIV (PWH) experience an increased vulnerability to premature aging and inflammation-associated comorbidities, even when HIV replication is suppressed by antiretroviral therapy (ART). However, the factors that contribute to or are associated with this vulnerability remain uncertain. In the general population, alterations in the glycomes of circulating IgGs trigger inflammation and precede the onset of aging-associated diseases. Here, we investigate the IgG glycomes of cross-sectional and longitudinal samples from 1,216 women and men, both living with virally suppressed HIV and those without HIV. Our glycan-based machine learning models indicate that living with chronic HIV significantly accelerates the accumulation of pro-aging-associated glycomic alterations. Consistently, PWH exhibit heightened expression of senescence-associated glycan-degrading enzymes compared to their controls. These glycomic alterations correlate with elevated markers of inflammatory aging and the severity of comorbidities, potentially preceding the development of such comorbidities. Mechanistically, HIV-specific antibodies glycoengineered with these alterations exhibit reduced anti-HIV IgG-mediated innate immune functions. These findings hold significant potential for the development of glycomic-based biomarkers and tools to identify and prevent premature aging and comorbidities in people living with chronic viral infections.

microbiology↗

bioRxiv2023

Diffusion Tensor Imaging: Influence of segmentation on fiber tracking in the supraspinatus muscle - an inter-operator reliability analysis

The ability of muscle to generate force depends on its architecture and quality. MR-based diffusion tensor imaging of muscle (mDTI) is an innovative approach for showing the fiber arrangement for the whole muscle volume. For accurate calculations of fiber metrics, muscle segmentation prior to tractography seems mandatory. Since segmentation is known to be operator dependent, it is important to understand how segmentation affects tractography. The aim of this study was to compare the results of deterministic fiber tracking based on muscle models generated by two independent operators. In addition, this study compares the results with a segmentation-free approach. Fifteen subjects underwent mDTI of the right shoulder. The results showed that mDTI can be successfully applied to complex joints such as the human shoulder. Furthermore, operators segmentation did not influence the results of fiber tracking and showed excellent intraclass correlation estimates ([≥] 0.975). As an exploratory approach, the segmentation-free fiber tracking showed significant differences in terms of mean fascicle length. Based on these findings, we assume that tractography does not require a detailed muscle segmentation. Furthermore, it implies that mDTI and automatic segmentation approaches or even a segmentation-free analysis can be considered for evaluation of muscle changes.

physiology↗

bioRxiv2020

The Chemical Structure of Widespread Microbial Aryl Polyene Lipids

Biosynthetic gene clusters (BGC) involved in aryl polyene (APE) biosynthesis are supposed to represent the most widespread BGC in the bacterial world.[1-3] Still, only hydrolysis products[4-8] and not the full-length product(s) have been identified, hindering studies on their biosynthesis and natural function. Here, we apply subsequent chromatographic separations to purify the aryl polyene-containing lipids (APELs) from the entomopathogenic bacterium Xenorhabdus doucetiae. Structure elucidation using a combination of isotope labeling, nuclear magnetic resonance techniques, and tandem mass spectrometry reveals an array of APELs featuring an all-trans C26:5 conjugated fatty acyl and a galactosamine-phosphate-glycerol moiety. In combination with extensive genetic studies, this research broadens the bacterial natural product repertoire and paves the way for future functional characterization of this almost universal microbial compound class. Due to their protective function against reactive oxygen species,[5,9] APELs might be important for virulence or symbiosis, mediating organismic interactions in several ecological niches.

microbiology↗