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Behavioural flexibility plays a major role in the way animals cope with novel situations, and physiological stress responses are adaptive and highly efficient mechanisms to cope with unpredictable events. Previous studies investigating the role of stress responses in mediating behavioural flexibility were mostly done in laboratory rodents using stressors and cognitive challenges unrelated to the ecology of the species. To better understand how stress mediates behavioural flexibility in a natural context, direct manipulations of the stress response and cognitive tests in ecologically relevant contexts are needed. To this aim, we pharmacologically blocked glucocorticoid receptors (GR) in adult Neolamprologus pulcher using a minimally invasive application of a GR antagonist. GR blockade prevents the recovery after a stressful event, which we predicted to impair behavioural flexibility. After the application of the GR antagonist, we repeatedly exposed fish to a predator and tested their behavioural flexibility using a detour task, i.e. fish had to find a new, longer route to the shelter when the shortest route was blocked. While the latencies to find the shelter were not different between treatments, GR blocked fish showed more failed attempts during the detour tasks than control fish. Furthermore, weak performance during the detour tasks was accompanied by an increase of fear related behaviours. This suggests that blocking GR changed the perception of fear and resulted in an impaired behavioural flexibility. Therefore, our results support a potential link between the capacity to recover from stressors and behavioural flexibility in N. pulcher with potential consequences for an effective and adaptive coping with changing environments., Competing Interests: Declaration of competing interest We declare no conflict of interest., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Stress is a collective term for certain conditions and sequences of physiological events enabling living organisms to overcome unpredictable and uncontrollable situations. The context-dependent nature, multidimensional course and large individual variability make stress responses difficult to measure. In avian species, a plethora of studies on short-term stress responses have been conducted by measuring the corticosteroid response to a standardized stress protocol. Here we aimed to test the viability of the leukocyte coping capacity (LCC), measuring oxygen radical production by leukocytes, to assess short-term stress in birds. We collected blood samples from captive house sparrows (Passer domesticus) in the two seasons of winter and spring, right after capture and 30min thereafter. In order to assess the overall physiological stress response to a standardized stressor, i.e. handling and temporary constraint, we measured LCC and additionally combined it with measures of total circulating glucocorticoids (GCs) and oxidative stress. All three methodologies detected significant changes due to the stressor albeit they were not correlated with each other and revealed different information. There was no significant change in oxidative stress levels between the two time points although the amount of relative oxidative damage as well as the anti-oxidative capacity changed significantly. We observed a significant seasonal difference in GC stress response with no difference between sexes. On the contrary, LCC measures revealed with a high individual consistency, that individuals experienced a similar magnitude of stress in both seasons with a significant difference between sexes. Total GC-levels have to be interpreted with caution regarding the assessment of short-term stress reactions. We therefore suggest to supplementary combine classical approaches for measuring stress with the immunological tool of LCC. Our results reveal LCC as a strong and reliable tool to assess short-term stress in captive house sparrows and as promising for other bird species. Collectively the study highlights the necessity to incorporate a range of physiological systems and their endpoints to measure and to assess stress reactions effectively., (Copyright © 2017 Elsevier Inc. All rights reserved.)

The potency assay for the freeze-dried live attenuated rubella vaccine is a cell culture based biological assay. The aim of our study was to perform the robustness testing of the rubella vaccine potency assay prior to validation. Seven intra-assay operating conditions that could have an effect on the assay performance were identified and their influence on the overall assay variability investigated by fractional factorial design of experiments (DoE). The robustness testing through DoE showed that the rubella vaccine potency assay is a robust assay. Critical operating conditions can be identified using DoE, which indicates that it is a suitable approach in bioassay robustness studies., (Copyright 2010 Elsevier Ltd. All rights reserved.)

The aim of this study was the molecular characterization of a historical mumps isolate (an alleged individual sample). After RNA extraction and cDNA synthesis, selective nested PCR amplification with specific primers, automated DNA sequencing and RFLP analyses were performed. The relative ratios of the detected virus sequences were determined by GeneScan electrophoresis. Phylogenetic tree based on the 316 nucleotide region of the SH gene of the mumps virus was generated by the neighbor-joining method. Results obtained by the described molecular approach show: (a) there are two mumps virus variants, A and B, detected in the fourth passage of wild type virus in the amniotic cavity of embryonated chicken eggs (ECE); (b) variants A and B belong to different genotypes; (c) variants A and B differ in the HN and NP genes which code for amino acid sequences comprising immunogenic epitopes; (d) variant B contains one or more minor variants. We discuss whether the observed differences between the two variants are a consequence of natural heterogeneity or of laboratory contamination in the early passages.