Biology subjects

Menzel, R.

Publications and source records attributed to Menzel, R..

11 recordsLinked to original sources

bioRxiv2024

Landmark knowledge overrides optic flow in honeybee waggle dance distance estimation

Honeybees encode in their waggle dances the vector (distance and direction) of an outbound flight to a food source or a new nest side. Optic flow has been identified as the major source of information in the distance estimation. Additional components of distance estimation were also identified, e.g. the sequence of experienced landmarks. Here we address the question of whether bees also use the landscape memory developed during exploratory orientation flights to estimate distance. We took advantage of the fact that flights in a narrow tunnel lead to further distance measures due to higher optic flow. We find that this effect is lost when bees had explored the area in which the tunnel is located and when they have somewhat restricted visual access to the surrounding environment through the mesh on top of the tunnel. These data are interpreted in the context of other findings about the structure of navigational memory in bees that develops during exploratory orientation flights. In particular, the data suggest that bees embed distance measures into a representation of navigational space that stores previously experienced landscape features. Summary statementThe distance code in the honeybee waggle dance is embedded in the landscape memory that bees establish during their exploratory and their foraging flights.

animal behavior and cognition↗

bioRxiv2023

Behavioral and genetic correlates of heterogeneity in learning performance in individual honeybees, Apis mellifera

Learning an olfactory discrimination task leads to heterogeneous results in honeybees with bees performing very well and others at low rates. Here we investigated this behavioral heterogeneity and asked whether it is associated with particular gene expression patterns. Bees were individually conditioned in a sequential conditioning protocol involving several phases of olfactory learning and retention tests. The rate of CS+ odor learning was found to correlate highest with a cumulative performance score extracted from all learning and retention tests. The cumulative score was used to sort the tested bees into high and low performers. Microarray analysis of gene expression in the mushroom body area of the brains of these bees disclosed a list of genes, which were differentially expressed between the high and low performers. These candidate genes are implicated in diverse biological functions, such as neurotransmission, memory formation, cargo trafficking and development.

animal behavior and cognition↗

bioRxiv2022

Generalization and Transfer of Navigation Memory in Honeybees

AO_SCPLOWBSTRACTC_SCPLOWFlying insects like the honeybee learn multiple features of the environment for efficient navigation. Here we ask whether the memory of such features is generalized to novel test conditions. Foraging bees from colonies located in 5 different home areas were tested in a common area for their search flights. Harmonic radar was used to track the search flights of the bees. The test area resembled partly or not at all the layout of landmarks in the respective home areas. Random search as the only guide for searching was excluded by two model calculations. The generalization and transfer effect was quantified by a partial least squares regression analysis of the guiding effect of the ground structures in the test area. Classification was performed with a support vector machine in order to account for optimal hyperplanes. A rank order of well separated clusters was found that partly resemble the graded differences between the ground structures of the home areas and the test area. We conclude that foragers guide their search flights by a generalization and transfer process that is based on their acquired navigation memory. The conclusion is discussed in the context of the learning and generalization process in an insect, the honeybee. SO_SCPLOWUMMARYC_SCPLOW SO_SCPLOWTATEMENTC_SCPLOWA new test procedure is applied to address the question whether a flying insect, the honeybee, uses a navigation memory that can be generalized to novel environmental conditions.

animal behavior and cognition↗

bioRxiv2022

Honey Bees Get Map Coordinates from the Dance

Honeybees (Apis mellifera carnica) communicate the rhumb line to a food source (its direction and distance from the hive) by means of a waggle dance. We ask whether bees recruited by the dance use it only as a flying instruction or also translate it into a location vector in a map-like memory, so that information about spatial relations of environmental cues informs their attempts to find the source. The flights of recruits captured on exiting the hive and released at distant sites were tracked by radar. The recruits performed first a straight flight in the direction of the rhumb line. However, the vector portions of their flights and the ensuing tortuous search portions were strongly and differentially affected by the release site. Searches were biased toward the true location of the food and away from the location specified by translating the rhumb line origin to the release site. We conclude that by following the dance a recruit gets two messages, a polar flying instruction (the rhumb line) and its conversion to Cartesian map coordinates.

animal behavior and cognition↗

bioRxiv2022

Aryl hydrocarbon receptor-dependent and -independent pathways mediate curcumin anti-aging effects

The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor whose activity can be modulated by polyphenols such as curcumin. AhR and curcumin have evolutionarily conserved effects on aging. Here, we investigated whether and how the AhR mediates the anti-aging effects of curcumin across species. Using a combination of in vivo, in vitro, and in silico analyses, we demonstrated that curcumin has AhR-dependent or -independent effects in a context-specific manner. We found that in Caenorhabditis elegans, AhR mediates curcumin-induced lifespan extension, most likely through a ligand-independent inhibitory mechanism related to its antioxidant activity. Curcumin also showed AhR-independent anti-aging activities such as protection against aggregation-prone proteins and oxidative stress in C. elegans and promotion of the migratory capacity of human primary endothelial cells. These AhR-independent effects are largely mediated by the Nrf2/SKN-1 pathway. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=113 SRC="FIGDIR/small/479676v1_ufig1.gif" ALT="Figure 1"> View larger version (27K): org.highwire.dtl.DTLVardef@15ccf21org.highwire.dtl.DTLVardef@22886eorg.highwire.dtl.DTLVardef@12b211eorg.highwire.dtl.DTLVardef@8b4474_HPS_FORMAT_FIGEXP M_FIG C_FIG

molecular biology↗

bioRxiv2022

In-vivo egfp expression in the honeybee Apis mellifera induced by electroporation and viral expression vector.

In this study we describe egfp expression induced by two techniques: in vivo electroporation and viral transduction in several cell types of the adult honeybee brain. Non-neuronal and neuronal cell types were identified and the expression persisted at least during three days. Kenyon cells, optic lobe neurons and protocerebral lobe neurons were electroporated. Astrocyte-like glia cells, fibrous lamellar glia cells and cortex glia cells were identified. Viral transduction targeted one specific type of glia cells that could not be identified. EGFP positive cells were rather variable after electroporation, and viral transduction resulted in more homogenous groups of positive cells. We propose that these techniques remain a good alternative to transgenic animals because they potentially target only somatic cells.

neuroscience↗

bioRxiv2021

Single neuron activity predicts behavioral performance of individual animals during memory retention

In 1972 Rescorla and Wagner formulated their model of classical Pavlovian conditioning postulating that the associative strength of a stimulus is expressed directly in the behavior it elicits1. Many biologists and psychologists were inspired by this model, and numerous experiments thereafter were interpreted assuming that the magnitude of the conditioned response (CR) reflects an associative effect at the physiological level. However, a correlation between neural activity and the expression of the CR in individual animals has not yet been reported. Here we show that, following differential odor conditioning, the change in activity of single mushroom body output neurons (MBON) of the honeybee predicts the behavioral performance of the individual during memory retention. The encoding of the stimulus-reward association at the mushroom body output occurs about 600 ms before the initiation of the CR. We conclude that the MB provides a stable representation of the stimulus-reward associative strength, and that this representation is required for behavioral decision-making during memory retention.

neuroscience↗

bioRxiv2020

InsectBrainDatabase - A unified platform to manage, share, and archive morphological and functional data

Insect neuroscience generates vast amounts of highly diverse data, of which only a small fraction are findable, accessible and reusable, despite open data mandates by funding bodies. We have therefore developed the InsectBrainDatabase (IBdb), an open platform for depositing, sharing and managing a wide range of insect neuroanatomical and functional data. It facilities biological insight by enabling effective cross-species comparisons, by intimately linking data on structure and function, and by serving as hub for information on insect neuroethology. The IBdb provides novel visualization and search tools, which are also available in a unique private mode of the database, before data is made public. This allows users to manage and visualize unpublished data, creating a strong incentive for data contribution and eliminating additional effort when publicly depositing the data at a later stage. These design principles could also serve as a blueprint for similar databases in other fields.

neuroscience↗

bioRxiv2020

Ahr-bacterial diet interaction modulates aging and associated pathologies in C. elegans

Genetic and environmental factors concurrently shape the aging process. The nematode Caenorhabditis elegans has been instrumental in the past 30 years to identify most genes and interventions nowadays known to modulate aging (Lopez-Otin et al. 2013, Tigges et al. 2014, Dato et al. 2017). The aryl-hydrocarbon-receptor (AhR) was discovered as a dioxin-binding transcription factor involved in the metabolism of different environmental toxicants and xenobiotics (Poland et al. 1976). Since then, the variety of pathophysiological processes regulated by the AhR has rapidly grown, ranging from the immune response to cell death and metabolic pathways, and we disclosed it promotes aging phenotypes across species (Eckers et al. 2016, Esser et al. 2018). Interestingly, many AhR modulators may impact on aging and age-associated pathologies, but, whether their effects are actually AhR-dependent has never been explored. Here, we show for the first time that lack of C. elegans AHR-1 affects health and lifespan in a context-dependent manner. Using known mammalian AhR modulators we found that, similar to mammals, ahr-1 has protective effects against environmental insults and identified a new role for AhR-bacterial diet interaction in animal lifespan, stress resistance, and age-associated pathologies. We narrowed down the dietary factor involved in the observed AhR-dependent features to a bacterially-extruded metabolite likely involved in tryptophan metabolism. This is the first study clearly establishing C. elegans as a good model organism to investigate evolutionarily conserved functions of AhR-modulators and -regulated processes, indicating it can be exploited to contribute to the discovery of novel information about AhR in mammals. Significance StatementThe roundworm C. elegans has been instrumental for the identification of many of the genetic and environmental factors known to concurrently shape the aging process. The aryl-hydrocarbon-receptor (AhR) was originally discovered as a dioxin-binding transcription factor involved in the metabolism of environmental toxicants and, in the past, we found it promotes aging phenotypes across species. Many AhR modulators may impact on aging and age-associated pathologies, but, whether their effects are actually AhR-dependent has never been explored. We show here for the first time that C. elegans AhR has protective effects against environmental insults such as UVB radiations and the xenobiotic BaP and identified a new critical role for AhR-bacterial diet interaction in animal lifespan, stress resistance, and age-associated pathologies.

physiology↗

bioRxiv2020

Biogenic Amine Neurotransmitters Promote Eicosanoid Production And Protein Homeostasis

Multicellular organisms use multiple pathways to restore protein homeostasis (proteostasis) in response to adverse physiological conditions, changing environment, and developmental aging. The nervous system can regulate proteostasis in different tissues, but it is unclear how it mobilizes proteostasis pathways to offset physiological decline. Here we show that C. elegans employs the humoral biogenic amine neurotransmitters dopamine, serotonin, and tyramine to regulate proteostasis and the activity of the Ubiquitin Proteasome System (UPS) in epithelial tissues. Mutants for biogenic amine synthesis show decreased poly-ubiquitination and turnover of a GFP-based UPS substrate. Using RNA-seq, we determined the expression profile of genes regulated by biogenic amine signaling. We find that biogenic amines promote the expression of a subset of cytochrome P450 monooxygenases involved in eicosanoid production from polyunsaturated fatty acids (PUFAs). Mutants for these P450s share the same UPS phenotype observed in biogenic amine mutants. The production of n-3 PUFAs is required for UPS substrate turnover, whereas mutants that accumulate n-3 PUFAs show accelerated turnover of this GFP-based substrate. Our results suggest that neurosecretory sensory neurons release biogenic amines to modulate the lipid signaling profile, which in turn activates stress response pathways to maintain proteostasis.

neuroscience↗

bioRxiv2019

Innovation in solitary bees is driven by exploration, shyness and activity levels

Behavioural innovation is widely considered an important mechanism by which animals respond to novel environmental challenges, including those induced by human activities. Despite its functional and ecological relevance, much of our current understanding of the innovation process comes from studies in vertebrates. Understanding innovation processes in insects has lagged behind partly because they are not perceived to have the cognitive machinery required to innovate. This perception is however challenged by recent evidence demonstrating sophisticated cognitive capabilities in insects despite their small brains. Here, we study the innovation capacity of a solitary bee (Osmia cornuta) in the laboratory by exposing naive individuals to an obstacle removal task. We also studied the underlying cognitive and non-cognitive mechanisms through a battery of experimental tests designed to measure learning, exploration, shyness and activity levels. We found that solitary bees can innovate, with 11 of 29 individuals (38%) being able to solve a new task consisting in lifting a lid to reach a reward. The propensity to innovate was uncorrelated with learning capacities, but increased with exploration, boldness and activity. These results provide solid evidence that non-social insects can innovate, and highlight the importance of interpreting innovation in the light of non-cognitive processes.

animal behavior and cognition↗