Daniel Normen Düring

Bio: Daniel Normen Düring is an academic researcher from University of Zurich. The author has contributed to research in topics: Zebra finch & Vocal learning. The author has an hindex of 7, co-authored 14 publications receiving 390 citations. Previous affiliations of Daniel Normen Düring include Max Planck Society & Free University of Berlin.

The songbird syrinx morphome: a three-dimensional, high-resolution, interactive morphological map of the zebra finch vocal organ

Abstract: Like human infants, songbirds learn their species-specific vocalizations through imitation learning. The birdsong system has emerged as a widely used experimental animal model for understanding the underlying neural mechanisms responsible for vocal production learning. However, how neural impulses are translated into the precise motor behavior of the complex vocal organ (syrinx) to create song is poorly understood. First and foremost, we lack a detailed understanding of syringeal morphology. To fill this gap we combined non-invasive (high-field magnetic resonance imaging and micro-computed tomography) and invasive techniques (histology and micro-dissection) to construct the annotated high-resolution three-dimensional dataset, or morphome, of the zebra finch (Taeniopygia guttata) syrinx. We identified and annotated syringeal cartilage, bone and musculature in situ in unprecedented detail. We provide interactive three-dimensional models that greatly improve the communication of complex morphological data and our understanding of syringeal function in general. Our results show that the syringeal skeleton is optimized for low weight driven by physiological constraints on song production. The present refinement of muscle organization and identity elucidates how apposed muscles actuate different syringeal elements. Our dataset allows for more precise predictions about muscle co-activation and synergies and has important implications for muscle activity and stimulation experiments. We also demonstrate how the syrinx can be stabilized during song to reduce mechanical noise and, as such, enhance repetitive execution of stereotypic motor patterns. In addition, we identify a cartilaginous structure suited to play a crucial role in the uncoupling of sound frequency and amplitude control, which permits a novel explanation of the evolutionary success of songbirds.

Universal mechanisms of sound production and control in birds and mammals

Abstract: As animals vocalize, their vocal organ transforms motor commands into vocalizations for social communication. In birds, the physical mechanisms by which vocalizations are produced and controlled remain unresolved because of the extreme difficulty in obtaining in vivo measurements. Here, we introduce an ex vivo preparation of the avian vocal organ that allows simultaneous high-speed imaging, muscle stimulation and kinematic and acoustic analyses to reveal the mechanisms of vocal production in birds across a wide range of taxa. Remarkably, we show that all species tested employ the myoelastic-aerodynamic (MEAD) mechanism, the same mechanism used to produce human speech. Furthermore, we show substantial redundancy in the control of key vocal parameters ex vivo, suggesting that in vivo vocalizations may also not be specified by unique motor commands. We propose that such motor redundancy can aid vocal learning and is common to MEAD sound production across birds and mammals, including humans.

Differential coexpression of FoxP1, FoxP2, and FoxP4 in the Zebra Finch (Taeniopygia guttata) song system

Abstract: Heterozygous disruptions of the Forkhead transcription factor FoxP2 impair acquisition of speech and language. Experimental downregulation in brain region Area X of the avian ortholog FoxP2 disrupts song learning in juvenile male zebra finches. In vitro, transcriptional activity of FoxP2 requires dimerization with itself or with paralogs FoxP1 and FoxP4. Whether this is the case in vivo is unknown. To provide the means for future functional studies we cloned FoxP4 from zebra finches and compared regional and cellular coexpression of FoxP1, FoxP2, and FoxP4 mRNA and protein in brains of juvenile and adult male zebra finches. In the telencephalic song nuclei HVC, RA, and Area X, the three investigated FoxPs were either expressed alone or occurred in specific combinations with each other, as shown by double in situ hybridization and triple immunohistochemistry. FoxP1 and FoxP4 but not FoxP2 were expressed in RA and in the HVCRA and HVCX projection neurons. In Area X and the surrounding striatum the density of neurons expressing all three FoxPs together or FoxP1 and FoxP4 together was significantly higher than the density of neurons expressing other combinations. Interestingly, the proportions of Area X neurons expressing particular combinations of FoxPs remained constant at all ages. In addition, FoxP-expressing neurons in adult Area X express dopamine receptors 1A, 1B, and 2. Together, these data provide the first evidence that Area X neurons can coexpress all avian FoxP subfamily members, thus allowing for a variety of regulatory possibilities via heterodimerization that could impact song behavior in zebra finches.

Expansion Light Sheet Microscopy Resolves Subcellular Structures in Large Portions of the Songbird Brain

Abstract: Expansion microscopy and light sheet imaging (ExLSM) provide a viable alternative to existing tissue clearing and large volume imaging approaches. The analysis of intact volumes of brain tissue presents a distinct challenge in neuroscience. Recent advances in tissue clearing and light sheet microscopy have re-addressed this challenge and blossomed into a plethora of protocols with diverse advantages and disadvantages. While refractive index matching achieves near perfect transparency and allows for imaging at large depths, the resolution of cleared brains is usually limited to the micrometer range. Moreover, the often long and harsh tissue clearing protocols hinder preservation of native fluorescence and antigenicity. Here we image large expanded brain volumes of zebra finch brain tissue in commercially available light sheet microscopes. Our expansion light sheet microscopy (ExLSM) approach presents a viable alternative to many clearing and imaging methods because it improves on tissue processing times, fluorophore compatibility, and image resolution.

Tissue Clearing and Light Sheet Microscopy: Imaging the Unsectioned Adult Zebra Finch Brain at Cellular Resolution.

Abstract: The inherent complexity of brain tissue, with brain cells intertwining locally and projecting to distant regions, has made three-dimensional visualization of intact brains a highly desirable but challenging task in neuroscience. The natural opaqueness of tissue has traditionally limited researchers to techniques short of single cell resolution such as computer tomography or magnetic resonance imaging. By contrast, techniques with single-cell resolution required mechanical slicing into thin sections, which entails tissue distortions that severely hinder accurate reconstruction of large volumes. Recent developments in tissue clearing and light sheet microscopy have made it possible to investigate large volumes at micrometer resolution. The value of tissue clearing has been shown in a variety of tissue types and animal models. However, its potential for examining the songbird brain remains unexplored. Songbirds are an established model system for the study of vocal learning and sensorimotor control. They share with humans the capacity to adapt vocalizations based on auditory input. Song learning and production are controlled in songbirds by the song system, which forms a network of interconnected discrete brain nuclei. Here, we use the CUBIC and iDISCO+ protocols for clearing adult songbird brain tissue. Combined with light sheet imaging, we show the potential of tissue clearing for the investigation of connectivity between song nuclei, as well as for neuroanatomy and brain vasculature studies.

Diffusible iodine‐based contrast‐enhanced computed tomography (diceCT): an emerging tool for rapid, high‐resolution, 3‐D imaging of metazoan soft tissues

Abstract: Morphologists have historically had to rely on destructive procedures to visualize the three-dimensional (3-D) anatomy of animals. More recently, however, non-destructive techniques have come to the forefront. These include X-ray computed tomography (CT), which has been used most commonly to examine the mineralized, hard-tissue anatomy of living and fossil metazoans. One relatively new and potentially transformative aspect of current CT-based research is the use of chemical agents to render visible, and differentiate between, soft-tissue structures in X-ray images. Specifically, iodine has emerged as one of the most widely used of these contrast agents among animal morphologists due to its ease of handling, cost effectiveness, and differential affinities for major types of soft tissues. The rapid adoption of iodine-based contrast agents has resulted in a proliferation of distinct specimen preparations and scanning parameter choices, as well as an increasing variety of imaging hardware and software preferences. Here we provide a critical review of the recent contributions to iodine-based, contrast-enhanced CT research to enable researchers just beginning to employ contrast enhancement to make sense of this complex new landscape of methodologies. We provide a detailed summary of recent case studies, assess factors that govern success at each step of the specimen storage, preparation, and imaging processes, and make recommendations for standardizing both techniques and reporting practices. Finally, we discuss potential cutting-edge applications of diffusible iodine-based contrast-enhanced computed tomography (diceCT) and the issues that must still be overcome to facilitate the broader adoption of diceCT going forward.

The Natural Biotic Environment of Caenorhabditis elegans .

Abstract: Organisms evolve in response to their natural environment. Consideration of natural ecological parameters are thus of key importance for our understanding of an organism’s biology. Curiously, the natural ecology of the model species Caenorhabditis elegans has long been neglected, even though this nematode has become one of the most intensively studied models in biological research. This lack of interest changed ∼10 yr ago. Since then, an increasing number of studies have focused on the nematode’s natural ecology. Yet many unknowns still remain. Here, we provide an overview of the currently available information on the natural environment of C. elegans. We focus on the biotic environment, which is usually less predictable and thus can create high selective constraints that are likely to have had a strong impact on C. elegans evolution. This nematode is particularly abundant in microbe-rich environments, especially rotting plant matter such as decomposing fruits and stems. In this environment, it is part of a complex interaction network, which is particularly shaped by a species-rich microbial community. These microbes can be food, part of a beneficial gut microbiome, parasites and pathogens, and possibly competitors. C. elegans is additionally confronted with predators; it interacts with vector organisms that facilitate dispersal to new habitats, and also with competitors for similar food environments, including competitors from congeneric and also the same species. Full appreciation of this nematode’s biology warrants further exploration of its natural environment and subsequent integration of this information into the well-established laboratory-based research approaches.

Long Noncoding RNAs in Cancer and Therapeutic Potential.

Abstract: Long noncoding RNAs (lncRNAs) are the major elements of the mammalian transcriptome that is emerging as a central player controlling diverse cellular mechanisms. Most of the well-studied lncRNAs so far are found to be crucial in regulating cellular processes such as cell cycle, growth, and apoptosis that ensure homeostasis. Owing to their location and distribution in the genome, lncRNAs influence the transcription of a wide range of proteins directly or indirectly by transcriptional and posttranscriptional alterations, which opens up the "LncRNA-cancer paradigm" in a context-dependent manner, i.e., either oncogenic or tumor suppressive. Thus, this chapter is a consolidation of lncRNA association in exhibiting or suppressing the typical cancer hallmarks such as continuous proliferation, surpassing apoptosis, genomic instability, drug resistance, invasion, and metastasis studied till date. In addition, special focus has been given on the efficient application of lncRNAs as potential targets for therapeutics that holds a great promise for future cancer therapy.

The whistle and the rattle: The design of sound producing muscles (rattlesnakeytoadfishycalcium transientsymuscle mechanicsyswimbladder)

Abstract: Vertebrate sound producing muscles often operate at frequencies exceeding 100 Hz, making them the fastest vertebrate muscles. Like other vertebrate muscle, these sonic muscles are ''synchronous,'' necessitating that calcium be released and resequestered by the sarcoplasmic reticulum during each contraction cycle. Thus to operate at such high frequencies, vertebrate sonic muscles require extreme adap- tations. We have found that to generate the ''boatwhistle'' mating call ('200 Hz), the swimbladder muscle fibers of toadfish have evolved (i) a large and very fast calcium transient, (ii) a fast crossbridge detachment rate, and (iii) probably a fast kinetic off-rate of Ca 21 from troponin. The fibers of the shaker muscle of rattlesnakes have independently evolved similar traits, permitting tail rattling at '90 Hz. Skeletal muscle fibers perform a wide range of activities, and different fiber types are accordingly designed to operate at different speeds and frequencies (1). A number of modifica- tions appear to underlie this diversity. For example, in loco- motory muscle, compared with slow twitch fibers, fast twitch fibers have a faster myosin with a higher maximum velocity of shortening (Vmax) (2, 3), a greater content of sarcoplasmic reticulum (SR), and its associated Ca 21 pumps (4, 5), a different isoform of the SR Ca 21 pump (SERCA1 in fast versus SERCA2 in slow) (6, 7) and a greater concentration of parvalbumin (a soluble protein that binds both calcium and magnesium) (5, 8). There is also evidence that fast fibers have a briefer myoplasmic free Ca 21 concentration ((Ca 21 )) tran- sient (9, 10) and less sensitive force-pCa relationship (11, 12). To understand the physiological modifications that underlie very rapid contractions, we have studied two of the fastest vertebrate muscles known. Both of these ''sonic'' muscles are used to produce sounds at the frequency at which the muscle contracts. The ''boatwhistle'' mating call of the male toadfish (Opsanus tau) is generated by '200 Hz contractions (25°C) of the muscles encircling the fish's gas-filled swimbladder (13- 15). The familiar ''rattle'' of the venomous western diamond- back rattlesnake (Crotalus atrox) is generated by '90 Hz contractions (35°C) of the shaker muscles at the base of the tail (16-19). The operational frequencies of these sonic muscles are 1-2 orders of magnitude higher than those of the loco- motory muscles in the same animals (0.5-5 Hz) (20). For fibers to operate at such high frequencies, they must activate and relax rapidly. Based on morphological and bio- chemical evidence from swimbladder of a very large SR Ca 21 pump density, a high density of SR Ca 21 release sites, and a large parvalbumin concentration, it has been proposed that an important modification of these sonic fibers is unusually rapid Ca 21 cycling (5, 21). By measuring myoplasmic free (Ca 21 ), we found that these fibers do indeed have unusual Ca 21 tran- sients—in fact the largest and fastest ever recorded. How- ever, our results showed that a fast Ca 21 transient alone is not sufficient for high frequency operation. By measuring Vmax, an index of crossbridge detachment rate, and the force-pCa relationship in skinned fibers, a possible index of troponin kinetics, we found that rapid activation and relax- ation likely also require a modification of the crossbridge kinetic rate, and probably a modification of the kinetics of Ca 21 -troponin binding. In reaching these conclusions, we first compared the above measurements in three fiber types from toadfish, ranging from slow twitch swimming fibers to the superfast twitch swimbladder fibers. We then compared the properties of rattlesnake shaker fibers with those of swimbladder.