Territorial choruses of giant otter groups (Pteronura brasiliensis) encode information on group identity

Group living animals often engage in corporate territorial defence. Territorial group vocalizations can provide information about group identity, size and composition. Neighbouring groups may use this information to avoid unfavourable direct conflicts. Giant otters are highly social and territorial animals with an elaborate vocal repertoire. They produce long-range screams when they are alert or excited, i.e. in an alarm, isolation or begging context. Long-range screams are not only produced by one individual at a time (‘single screams’) but also by multiple group members simultaneously, resulting in a highly conspicuous ‘group chorus’. Wild giant otters regularly produce group choruses during interactions with predators, when they detect intruders in their territory or before group reunions after separation. Since single screams and especially group choruses probably contribute to the groups’ corporate territorial defence, we hypothesized that group identity is encoded in single screams and group choruses. We analysed vocalizations from five wild and three captive giant otter groups and found statistical evidence for a group signature in group choruses. Results for single screams were less conclusive, which might have been caused by the comparatively lower sample size. We suggest that giant otters may gain information on group identity by listening to group choruses. Group identity likely constitutes important social information for giant otters since territory boundaries of neighbouring groups can overlap and direct inter-group conflicts are severe. Therefore, group chorusing may contribute to the mutual avoidance of members from different groups

Apoptosis in the Neuronal Lineage of the Mouse Olfactory Epithelium: Regulationin Vivoandin Vitro

AbstractThe olfactory epithelium (OE) of the mouse provides a unique system for understanding how cell birth and cell death interact to regulate neuron number during development and regeneration. We have examined cell death in the OE in normal adult mice; in adult mice subjected to unilateral olfactory bulbectomy (surgical removal of one olfactory bulb, the synaptic target of olfactory receptor neurons (ORNs) of the OE); and in primary cell cultures derived from embryonic mouse OE.In vivo,cells at all stages in the neuronal lineage—proliferating neuronal precursors, immature ORNs, and mature ORNs—displayed signs of apoptotic cell death; nonneuronal cells did not. Bulbectomy dramatically increased the number of apoptotic cells in the OE on the bulbectomized side. Shortly following bulbectomy, increased cell death involved neuronal cells of all stages. Later, cell death remained persistently elevated, but this was due to increased apoptosis by mature ORNs alone.In vitro,apoptotic death of both ORNs and their precursors could be inhibited by agents that prevent apoptosis in other cells: aurintricarboxylic acid (ATA), a membrane-permeant analog of cyclic AMP (CPT-cAMP), and certain members of the neurotrophin family of growth factors (brain-derived neurotrophic factor, neurotrophin 3, and neurotrophin 5), although no neurotrophin was as effective at promoting survival as ATA or CPT-cAMP. Consistent with observed effects of neurotrophins, immunohistochemistry localized the neurotrophin receptors trkB and trkC to fractions of ORNs scattered throughout neonatal OE. These results suggest that apoptosis may regulate neuronal number in the OE at multiple stages in the neuronal lineage and that multiple factors—potentially including certain neurotrophins—may be involved in this process

Multicolor Time-lapse Imaging of Transgenic Zebrafish: Visualizing Retinal Stem Cells Activated by Targeted Neuronal Cell Ablation

High-resolution time-lapse imaging of living zebrafish larvae can be utilized to visualize how biological processes unfold (for review see 1). Compound transgenic fish which express different fluorescent reporters in neighboring cell types provide a means of following cellular interactions 2 and/or tissue-level responses to experimental manipulations over time. In this video, we demonstrate methods that can be used for imaging multiple transgenically labeled cell types serially in individual fish over time courses that can span from minutes to several days. The techniques described are applicable to any study seeking to correlate the "behavior" of neighboring cells types over time, including: 1) serial 'catch and release' methods for imaging a large number of fish over successive days, 2) simplified approaches for separating fluorophores with overlapping excitation/emission profiles (e.g., GFP and YFP), 3) use of hypopigmented mutant lines to extend the time window available for high-resolution imaging into late larval stages of development, 4) use of membrane targeted fluorescent reporters to reveal fine morphological detail of individual cells as well as cellular details in larger populations of cells, and 5) a previously described method for chemically-induced ablation of transgenically targeted cell types; i.e., nitroreductase (NTR) mediated conversion of prodrug substrates, such as metronidazole (MTZ), to cytotoxic derivatives 3,5

Measurement of Interfacial Shear Mechanical Properties in Thermal Barrier Coating Systems by a Barb Pullout Method

A test technique has been developed to facilitate evaluation of the fracture characteristics of coatings and interfaces in thermal barrier coating (TBC) systems. The methodology has particular application in analyzing delamination crack growth, where crack propagation occurs under predominantly mode II loading. The technique has been demonstrated by quantitatively measuring the effective delamination fracture resistance of an electron-beam physical vapor deposition TBC

Studies of MCP-PMTs in the miniTimeCube neutrino detector

This report highlights two different types of cross-talk in the photodetectors of the miniTimeCube neutrino experiment. The miniTimeCube detector has 24 $8 \times 8$-anode Photonis MCP-PMTs Planacon XP85012, totalling 1536 individual pixels viewing the 2-liter cube of plastic scintillator