Forschung

Drittmittelprojekt: DFG, 199.050 EUR

Kliniken/Institute:
Institut für Zoologie

Projektdetails:
The role of NMDA receptors in neuronal plasticity is well established. However, their role in intracellular voltage-signaling and sensory processing is less well characterized, yet they are implicated in amplifying action potential firing rates. To understand the cellular basis for this NMDA dependent amplification of firing rate, its influence on sensory processing and the carried sensory information we will perform in vivo and in vitro recordings of neurons in the dorsal nucleus of the lateral lemniscus (DNLL) - an auditory brainstem structure important for binaural hearing. We will determine the synaptic interactions of excitation and inhibition with NMDA receptor conductances to understand their contributions to intracellular voltage-signaling in vitro. Using in vivo pharmacology we will answer what impact NMDA receptors have on sound driven firing rates. Thereby, the DNLL serves on the one hand as a read out nucleus where the impact of NMDA receptors on relaying binaural information will be quantified. On the other hand we will assay in vivo the direct binaural interactions at the level of the DNLL to understand the influence of NMDA receptors on interactions between inhibition and excitation. We hypothesize that these interactions might be crucial in terminating a long lasting inhibition that is regarded as a cellular correlate for the suppression of sound sources during echoes.

Resultate:

Felmy F.: The nuclei of the lateral lemniscus. The Oxford Handbook of auditory brainstem. Edited by Karl Kandler. 2019

 

Kladisios N., Fischer L., Felmy F.: Minimal Number of Required Inputs for Temporally Precise Action Potential Generation in Auditory Brainstem Nuclei. Front Cell Neurosci. 2020 Nov 5;14:592213

 

Siveke I., Lingner A., Ammer J.J., Gleiss S.A., Grothe B., Felmy F.: A Temporal Filter for Binaural Hearing Is Dynamically Adjusted by Sound Pressure Level. Front Neural Circuits. 2019 Feb 13; 13:8.

 

Siveke I., Ammer J.J., Gleiss S.A., Grothe B., Leibold C., Felmy F.: Electrogenic N-methyl-D-aspartate receptor signaling enhances binaural responses in the adult brainstem. European Journal of Neuroscience, 2018, 47, 858-865

Drittmittelprojekt: Alexander von Humboldt Stiftung Mohammed Bin Zayed Species Conservation

Kliniken/Institute:
Institut für Zoologie

Projektdetails:
The genus Eleutherodactylus, with over 194 known species and a distribution centered in the Caribbean West Indian islands, is the most speciose lineage of the Eleutherodactylidae family. These frogs represent over 80% of the Caribbean amphibian diversity with most of the species being single-island endemics. With the aid of multiple collaborators, this long term research project seeks to: 1) uncover cryptic diversity and define the species limits in the genus Eleutherodactylus by integrating genomic and phenotypic information; 2) elucidate the phylogenetic relationships among the species and related taxa; 3) compare the phenotypes, geographic distributions and evolutionary history across species to identify the factors responsible for the evolutionary diversification of amphibians in an insular scenario; and 4) generalize the results towards the long term conservation of these species.

Kooperationspartner:

Dr. Roberto Alonso Bosch, University of Havana, Cuba

MSc. Manuel Iturriaga Monsibay, Institute of Ecology and Systematics, Cuba

Prof. Dr. Miguel Vences, Technische Universität Braunschweig, Germany

Dr. Carles Vilà, Estación Biológica de Doñana, CSIC, Spain

Dr. Alejandro Gonzalez Voyer, Instituto de Ecología, UNAM, Mexico

Álvaro Dugo Cota, Estación Biológica de Doñana, CSIC, Spain

Drittmittelprojekt: DFG, 179.800 EUR

Kliniken/Institute:
Institut für Zoologie

Projektdetails:
Neurons in the ventral part of the ventral nucleus of the lateral lemniscus (VNLL) show highly precise temporal discharge patterns with high firing rates and low latencies upon monaural (contralateral) stimulation with amplitude-modulated sounds. Therefore, they are believed to play an important role in the processing of conspecific vocalization such as human speech. In this project we evaluate the hypothesis that the markedly biphasic shape of these neurons' excitatory synaptic currents is a key feature in understanding their response properties. To this end, we will quantitatively describe the synaptic dynamics of the afferent synapses and study the supra-threshold integration of these currents using a combination of electrophysiological recordings and a computational model of these neurons. Finally, we will quantify the information transfer and stimulus discriminability of the response patterns using conductance trains derived from human speech signals in experiments and model.

Resultate:

Kladisios N., Fischer L., Jenzen F., Rebhan M., Leibold C., Felmy F.: Synaptic Mechanisms underlying Temporally Precise Information Processing in the VNLL, an auditory brainstem nucleus. Journal of Neuroscience, 2022, Vol., 42, 6536-50

 

Felmy F., Meyer E.M.M.: Lateral lemniscus. The Senses, 2nd Edition, Chapter 2.27

 

Felmy F.: The nuclei of the lateral lemniscus. The Oxford Handbook of auditory brainstem. Edited by Karl Kandler. 2019

 

Fischer L., Leibold C., Felmy F.: Resonance Properties in Auditory Brainstem Neurons. Front Cell Neurosci. 2018 Jan 24; 12:8.

Kooperationspartner:

Prof. Dr. Christian Leibold, LMU-München

Drittmittelprojekt: DFG, 27.210 EUR

Kliniken/Institute:
Institut für Zoologie

Projektdetails:
The genetics of colouration has been studied in mammals, birds, fish and reptiles but studies on amphibian are scarce. Besides extensive variability in colour pattern nothing is known about the underlying genetic components involved in creating colour diversity within and among amphibian species. In this context the diversity of colouration patterns linked to predator avoidance strategies in Neotropical poison frogs is an exciting opportunity to study the genetics of ecological adaptation. Poison frogs differ in colouration patterns among populations and strong evidence exists that colouration is adaptive, probably driven by predator selection. The objective of this project is to characterize the colour pigments and the colouration genes for the extremely colour polymorphic Neotropical strawberry poison frog Oophaga pumilio. In this frog bright aposematic as well as duller cryptic colour morphs are present in different Panamanian populations.
For our project we will collect skin samples from three populations diverged in colour patterns: a red one, a green one and a blue one. We will perform RNAseq analysis on dorsal skin-derived cDNA. cDNA samples will be send to a sequencing service that will perform next generation sequencing to analyse differences in expression levels in genes involved in colouration. We expect that genes involved in the carotenoid /pteridin uptake, synthesis or storage differ in their expression level among colour morphs. We will confirm results for loci with significant expression differences by performing quantitative Real time-RT-PCR (RT=reverse transcription). Thus, we will determine the key gene expression differences underlying colour variation in this species. Our study will lead to a better understanding of causes and consequences of adaptive colouration.

Resultate:

Rodríguez A, Mundy N, Ibáñez R, Pröhl H (2020) Being red, blue and green: the genetic basis of coloration differences in the strawberry poison frog (Oophaga pumilio). BMC Genomics: 21. 10.1186/s12864-020-6719-5.

Kooperationspartner:

Dr. Nicolas Mundy, University of Cambridge, UK

Dr. Roberto Ibañéz, STRI, Panama

Drittmittelprojekt: EU-DEVELAGE, DAAD-Procope, University of Montpellier, 352.000 EUR

Kliniken/Institute:
Institut für Zoologie

Projektdetails:
A - Healthy Aging in Mouse Lemurs

Mouse lemurs belong to the basal primates (strepsirrhines) and represent the smallest nonhuman primates in the world. With a life span much shorter than in larger-bodied primates and the presence of tangles and beta-amyloid plaques in the brain of some, but not all, aged mouse lemurs, they may provide a unique natural primate model for aging research, relatively inexpensive to maintain and to breed. The potential of the mouse lemur as a primate model for AD-like diseases will depend on easily detectable phenotypic markers of AD-like diseases comparable to humans. The longterm aim of this project is thus to establish and validate behavioural, hormonal, cognitive, genetic, immunhistochemical and brain imaging tools to phenotype subjects, to apply them to discriminate between "wildtype" phenotypes and AD-like carriers and to validate thereby the primate brain aging model, mouse lemur. Within an EU-funded project, we aimed at establishing a behavioural test battery, comparable to CANTAB (CAmbridge Neuropsychological Test Automated Battery) in humans, to objectivly assess cognitive performances. Cognition can then be linked to potential markers of personality, longterm stress (hormones) and heredity. Furthermore, the use of MRI is developed to evaluate potential age-related brain atrophies and to link them to cognitive performance. Findings will be explored in an integrative approach to identify to which extent cognitive phenotypes are linked to behavioral/hormonal/genetic/ neurological phenotypes and may predict age-related cognitive dysfunctions. This approach will not only give first comparable insight into the behavioural syndromes and cognitive skills and its deficiencies during aging in the model mouse lemur, and thereby to cognition in a previously fairly neglected group of primates, the strepsirrhines, it will also shed light on fundamental cognitive building blocks from which our own unique human-specific intelligence derived.

B- Ocular Pathologies in Mouse Lemurs: a Comparison of Colonies with Different Life Cycles

Seasonal reproduction in mouse lemurs is strongly dependent on the photoperiod. The reduction of photoperiodically induced artificial seasonal cycles is suggested to accelerate their aging process. Two of the world?s largest self-sustaining breeding colonies with in total about 350 animals in all age classes are located in our labs at the University of Veterinary Medicine at Hannover in Germany and at the University of Montpellier in France. They are maintained and bred on a natural and an artificially accelerated photoperiod regime, respectively.
The short-term aim of this project is to standardize technical approaches to compare these colonies to examine to what extent different photoperiod regimes affect stress-related behavioural traits and ophthalmologic deficiencies. Further, validated opthalmologic techniques are applied to assess age-dependent dysfunction in the eye of mouse lemurs and to exclude animals with visual dysfunctions from vision-based cognitive research. The long-term aim of this project is to further explore the use of this primate model for aging research.

Resultate:

e.g.

 

Dubicanac M.; Joly M.; Strüve J.; Nolte I.; Mestre-Frances N.; Verdier J-M.; Zimmermann E (2017): Intraocular pressure in the smallest primate aging model, the gray mouse lemur. Vet. Ophthalmology, DOI:10.1111/vop.12434.

 

Lehman, S. M.; Radespiel, U.; Zimmermann, E.:

The Dwarf and Mouse Lemurs of Madagascar. Cambridge Studies in Biological and Evolutionary Anthropology, Band 73; Cambridge: Cambridge University Press, 2016, 592 S.

ISBN 9781107075597

http://www.cambridge.org/us/catalogue/catalogue.asp?isbn=9781107075597

 

Joly M, Ammersdörfer S, Schmidtke D, Zimmermann E (2014): Touchscreen-Based Cognitive Tasks Reveal Age-Related Impairment in a Primate Aging Model, the Grey Mouse Lemur (Microcebus murinus). PLoS One; DOI: 10.1371/journal.pone.0109393

 

Schopf C., Zimmermann E., Tünsmeyer J., Kästner S.B.R., Hubka P., Kral A. (2014): Hearing and Age-Related Changes in the Gray Mouse Lemur. Journal of the Association for Research in Otolaryngology; DOI 10.1007/s10162-014-0478-4

 

Schmidtke D., Ammersdörfer S., Joly M., Zimmermann E. (2018): First comparative approach to touchscreen-based visual object-location paired-associates learning in humans (Homo sapiens) and a nonhuman primate (Microcebus murinus). Journal of Comparative Psychology; DOI 10.1037/com0000116

Kooperationspartner:

Prof. Dr. J.-M. Verdier, École Pratique des Hautes Études (EPHE), Université PSL Paris, F

Dr. Marine Joly, Psychology, Portsmouth, GB

Prof. Dr. A. Kral, VIANNA, HNO, MHH

Prof. Dr. A. Bleich, Institut für Versuchstierkunde und Zentrales Tierlaboratorium der Medizinischen Hochschule Hannover

Dr. M. Heistermann, German Primate Center, Göttingen

Prof. Dr. G. Kovac, University of Toronto, CAN

Prof. Dr. Nadine Mestre-Francés, Université de Montpellier, F