Morphology of antennal hair field afferents, descending interneurons and mesothoracic motoneurons, and in situ calcium imaging of retrogradely labeled retractor coxae neurons in the stick insect.

The phasmid species Carausius morosus serves as an established animal for studying terrestrial locomotion and antennal movements for tactile exploration of the near-range environment, but neuroanatomical data is only limited available. In the first part of this thesis, fluorescent dye stainings of antennal hair field sensilla, which are important antennal joint angle sensors, and stainings of all antennal motor nerves were performed to receive detailed insights into the neuroanatomical organization of the stick insects’ antennal sensorimotor system. It was shown that afferents of all seven antennal hair fields (HF) send collaterals into the dorsal lobe, a deutocerebral neuropil region in the brain, and further descend through the circumoesophageal connective to the suboesophageal ganglion (SOG), where these afferents terminate. Moreover, double stainings of HFs located on different antennal segments and of HFs with different direction properties showed similar staining patterns, but differences were found in a spatially different formation of synaptic boutons within the entire depth of the dorsal lobe and within the SOG. In the dorsal lobe, HF afferents and projections of antennal motoneurons overlap, which could be an indication for direct synaptic contacts. Interestingly, stainings of the antennal nerve of the flagellum revealed another deutocerebral neuropil separated from the dorsal lobe, the ventral area of flagellum afferents described for crickets. Besides, thoracic connectives were stained to reveal somata of descending interneurons (DIN) located in the brain and SOG. Axonal backfills of cervical (neck) connectives revealed up to 410 cell bodies of DINs (brain: 205, SOG: 205), and backfills of connectives between the pro- and mesothoracic ganglia stained up to 173 DINs (brain: 83, SOG: 90). Furthermore, in double stainings of connectives and scapal HF sensilla it was observed that neurites of DINs seem to be in vicinity to afferents of HFs, which suggests that antennal HF signals are transmitted via a fast cephalothoracic pathway to thoracic motor centers. In the second part, the morphology of leg motoneurons, dorsal unpaired median neurons (DUM), and sensory neurons in the stick insect mesothoracic ganglion were examined. For this, cut ends of lateral nerves were retrogradely labeled with fluorescent dyes. Numbers of motoneurons and details of their structure by far exceed previously published data. Somata of excitatory motoneurons form clusters in the lateral ganglion cortex and their dendrites branch mainly in the dorsal neuropil. Nine DUM neurons were identified, six of which have axons in nervus lateralis 5, which innervates the retractor coxae muscles. Most sensory fibers terminate in the ventral association center (VAC). Twenty-three small cell bodies located close to the soma of the fast extensor tibiae motoneuron (FETi) likely belong to strand receptors. Stained structures are compared with previously published data from stick insects and other orthopteran insects. In the third part, a calcium (Ca2+) imaging method is introduced for retrograde loading cut ends of stick insect retractor coxae motoneuron axons with a Ca2+-sensitive fluorescent indicator. Intracellular Ca2+ changes were induced either by the application of the muscarinic acetylcholine agonist pilocarpine into the thoracic cavity and by tactile stimulation of the animal’s abdomen. The measured intracellular Ca2+ dynamics are very similar and temporarily uniform across primary and secondary motoneuron neurites. Calculated integrals of measured intracellular Ca2+ changes and integrals of retractor coxae spike activity revealed a linear correlation. This suggests that the observed changes in intracellular Ca2+ result from activation of voltage-gated Ca2+ channels by membrane depolarizations. Moreover, Ca2+ changes of lateral DUM neurites could be measured. A first analysis of pilocarpine-induced Ca2+ transients in presumed three different DUM neurites revealed regular and in-phase Ca2+ oscillations. These DUM neurite Ca2+ elevations have no fixed phase relation to either the protractor coxae nor the retractor coxae spike activity

Scientific opportunies for bERLinPro 2020+, report with ideas and conclusions from bERLinProCamp 2019

The Energy Recovery Linac (ERL) paradigm offers the promise to generate intense electron beams of superior quality with extremely small six-dimensional phase space for many applications in the physical sciences, materials science, chemistry, health, information technology and security. Helmholtz-Zentrum Berlin started in 2010 an intensive R\&D programme to address the challenges related to the ERL as driver for future light sources by setting up the bERLinPro (Berlin ERL Project) ERL with 50 MeV beam energy and high average current. The project is close to reach its major milestone in 2020, acceleration and recovery of a high brightness electron beam. The goal of bERLinProCamp 2019 was to discuss scientific opportunities for bERLinPro 2020+. bERLinProCamp 2019 was held on Tue, 17.09.2019 at Helmholtz-Zentrum Berlin, Berlin, Germany. This paper summarizes the main themes and output of the workshop

A connectome and analysis of the adult Drosophila central brain.

The neural circuits responsible for animal behavior remain largely unknown. We summarize new methods and present the circuitry of a large fraction of the brain of the fruit fly Drosophila melanogaster. Improved methods include new procedures to prepare, image, align, segment, find synapses in, and proofread such large data sets. We define cell types, refine computational compartments, and provide an exhaustive atlas of cell examples and types, many of them novel. We provide detailed circuits consisting of neurons and their chemical synapses for most of the central brain. We make the data public and simplify access, reducing the effort needed to answer circuit questions, and provide procedures linking the neurons defined by our analysis with genetic reagents. Biologically, we examine distributions of connection strengths, neural motifs on different scales, electrical consequences of compartmentalization, and evidence that maximizing packing density is an important criterion in the evolution of the fly's brain

Central projections of antennal hair fields and descending interneurons in stick insect brain and suboesophageal ganglion

Goldammer J, Dürr V. Central projections of antennal hair fields and descending interneurons in stick insect brain and suboesophageal ganglion. In: Proc. Göttingen Neurobiol. Conf. 2011: T20-4A

Proprioceptive input to a descending pathway conveying antennal postural information. Terminal organisation of antennal hair field afferents

Goldammer J, Dürr V. Proprioceptive input to a descending pathway conveying antennal postural information. Terminal organisation of antennal hair field afferents. Arthropod Structure & Development. 2018;47(5):465-481.Like several other arthropod species, stick insects use their antennae for tactile exploration of the near-range environment and for spatial localisation of touched objects. More specifically, Carausius morosus continuously moves its antennae during locomotion and reliably responds to antennal contact events with directed movements of a front leg. Here we investigate the afferent projection patterns of antennal hair fields (aHF), proprioceptors known to encode antennal posture and movement, and to be involved in antennal movement control. We show that afferents of all seven aHF of C. morosus have terminal arborisations in the dorsal lobe (DL) of the cerebral (=supraoesophageal) ganglion, and descending collaterals that terminate in a characteristic part of the gnathal (=suboesophageal) ganglion. Despite differences of functional roles among aHF, terminal arborisation patterns show no topological arrangement according to segment specificity or direction of movement. In the DL, antennal motoneuron neurites show arborizations in proximity to aHF afferent terminals. Despite the morphological similarity of single mechanoreceptors of aHF and adjacent tactile hairs on the pedicel and flagellum, we find a clear separation of proprioceptive and exteroceptive mechanosensory neuropils in the cerebral ganglion. Moreover, we also find this functional separation in the gnathal ganglio

Proprioceptive input to a descending pathway conveying antennal postural information: Terminal organisation of antennal hair field afferents

Like several other arthropod species, stick insects use their antennae for tactile exploration of the near range environment and for spatial localisation of touched objects. More specifically, Carausius morosus continuously moves its antennae during locomotion and reliably responds to antennal contact events with directed movements of a front leg. Here we investigate the afferent projection patterns of antennal hair fields (aHF), proprioceptors known to encode antennal posture and movement, and to be involved in antennal movement control. We show that afferents of all seven aHF of C. morosus have terminal arborisations in the dorsal lobe (DL) of the cerebral (=supraoesophageal) ganglion, and descending collaterals that terminate in a characteristic part of the gnathal (=suboesophageal) ganglion. Despite differences of functional roles among aHF, terminal arborisation patterns show no topological arrangement according to segment specificity or direction of movement. In the DL, antennal motoneuron neurites show arborizations in proximity to aHF afferent terminals. Despite the morphological similarity of single mechanoreceptors of aHF and adjacent tactile hairs on the pedicel and flagellum, we find a clear separation of proprioceptive and exteroceptive mechanosensory neuropils in the cerebral ganglion. Moreover, we also find this functional separation in the gnathal ganglion. (C) 2018 Elsevier Ltd. All rights reserved

Soma clusters of descending interneurons of the stick insect brain and gnathal ganglion

Goldammer J, Büschges A, Dürr V. Soma clusters of descending interneurons of the stick insect brain and gnathal ganglion. Bielefeld University; 2023.Research data underlying the publication Goldammer, Büschges and Dürr (in revision): Descending interneurons of the stick insect connecting brain neuropiles with the prothoracic ganglion. PLoS On

Descending interneurons of the stick insect connecting brain neuropiles with the prothoracic ganglion

Goldammer J, Buschges A, Dürr V. Descending interneurons of the stick insect connecting brain neuropiles with the prothoracic ganglion. PLoS ONE . 2023;18(8): e0290359.Stick insects respond to visual or tactile stimuli with whole-body turning or directed reach-to-grasp movements. Such sensory-induced turning and reaching behaviour requires interneurons to convey information from sensory neuropils of the head ganglia to motor neuropils of the thoracic ganglia. To date, descending interneurons are largely unknown in stick insects. In particular, it is unclear whether the special role of the front legs in sensory-induced turning and reaching has a neuroanatomical correlate in terms of descending interneuron numbers. Here, we describe the population of descending interneurons with somata in the brain or gnathal ganglion in the stick insect Carausius morosus, providing a first map of soma cluster counts and locations. By comparison of interneuron populations with projections to the pro- and mesothoracic ganglia, we then estimate the fraction of descending interneurons that terminate in the prothoracic ganglion. With regard to short-latency, touch-mediated reach-to-grasp movements, we also locate likely sites of synaptic interactions between antennal proprioceptive afferents to the deutocerebrum and gnathal ganglion with descending or ascending interneuron fibres. To this end, we combine fluorescent dye stainings of thoracic connectives with stainings of antennal hair field sensilla. Backfills of neck connectives revealed up to 410 descending interneuron somata (brain: 205 in 19 clusters; gnathal ganglion: 205). In comparison, backfills of the prothorax-mesothorax connectives stained only up to 173 somata (brain: 83 in 16 clusters; gnathal ganglion: 90), suggesting that up to 60% of all descending interneurons may terminate in the prothoracic ganglion (estimated upper bound). Double stainings of connectives and antennal hair field sensilla revealed that ascending or descending fibres arborise in close proximity of afferent terminals in the deutocerebrum and in the middle part of the gnathal ganglia. We conclude that two cephalothoracic pathways may convey cues about antennal movement and pointing direction to thoracic motor centres via two synapses only. Copyright: © 2023 Goldammer et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

Calcium imaging of CPG-evoked activity in efferent neurons of the stick insect

The stick insect is a well-established experimental animal to study the neural basis of walking. Here, we introduce a preparation that allows combining calcium imaging in efferent neurons with electrophysiological recordings of motor neuron activity in the stick insect thoracic nerve cord. The intracellular free calcium concentration in middle leg retractor coxae motor neurons and modulatory octopaminergic DUM neurons was monitored after backfilling lateral nerve nl5 that contains the axons of these neurons with the calcium indicator Oregon Green BAPTA-1. Rhythmic spike activity in retractor and protractor motor neurons was evoked by pharmacological activation of central pattern generating neuronal networks and recorded extracellularly from lateral nerves. A primary goal of this study was to investigate whether changes in the intracellular free calcium concentration observed in motor neurons during oscillatory activity depend on action potentials. We show that rhythmic spike activity in leg motor neurons induced either pharmacologically or by tactile stimulation of the animal is accompanied by a synchronous modulation in the intracellular free calcium concentration. Calcium oscillations in motor neurons do not appear to depend on calcium influx through voltage-sensitive calcium channels that are gated by action potentials because Calcium oscillations persist after pharmacologically blocking action potentials in the motor neurons. Calcium oscillations were also apparent in the modulatory DUM neurons innervating the same leg muscle. However, the timing of calcium oscillations varied not only between DUM neurons and motor neurons, but also among different DUM neurons. Therefore, we conclude that the motor neurons and the different DUM neurons receive independent central drive

A comparative radiation hybrid map of sheep chromosome 10

Comparative radiation hybrid (RH) maps of individual ovine chromosomes are essential to identify genes governing traits of economic importance in sheep, a livestock species for which whole genome sequence data are not yet available. The USUoRH5000 radiation hybrid panel was used to generate a RH map of sheep chromosome 10 (OAR10) with 59 markers that span 1,422 cR over an estimated 92 Mb of the chromosome, thus providing markers every 2 Mb (equivalent to every 24 cR). The markers were derived from 46 BAC end sequences (BESs), a single EST, and 12 microsatellites. Comparative analysis showed that OAR10 shares remarkable conservation of gene order along the entire length of cattle chromosome 12 and that OAR10 contains four major homologous synteny blocks, each related to segments of the homologous human chromosome 13. Extending the comparison to the horse, dog, mouse, and chicken genome showed that these blocks share conserved synteny across species