Maternal stress and early life stress affect development. Zebrafish (Danio rerio) are ideally suited to study this, as embryos develop externally into free-feeding larvae. The objective of this study was therefore to assess the effects of increased levels of cortisol, mimicking thereby maternal stress, on larval physiology and behaviour. We studied the effects in two common zebrafish strains, that is, AB and Tupfel long-fin (TL), to assess strain dependency of effects. Fertilized eggs were exposed to a cortisol-containing medium (1.1 μmol/l) or control medium from 0 to 6 h following fertilization, after which at 5-day following fertilization, larval behaviour and baseline hypothalamus–pituitary–interrenal cells axis functioning were measured. The data confirmed earlier observed differences between AB larvae and TL larvae: a lower hypothalamus–pituitary–interrenal axis activity in TL larvae than AB larvae, and slower habituation to repeated acoustic/vibrational stimuli in TL larvae than AB larvae. Following cortisol treatment, increased baseline levels of cortisol were found in AB larvae but not TL larvae. At the behavioural level, increased thigmotaxis or ‘wall hugging’ was found in AB larvae, but decreased thigmotaxis in TL larvae; however, both AB larvae and TL larvae showed decreased habituation to repeated acoustic/vibrational stimuli. The data emphasize that strain is a critical factor in zebrafish research. The habituation data suggest a robust effect of cortisol exposure, which is likely an adaptive response to increase the likelihood of detecting or responding to potentially threatening stimuli. This may enhance early life survival. Along with other studies, our study underlines the notion that zebrafish may be a powerful model animal to study the effects of maternal and early life stress on life history.
In this study we have assessed the effects of increased cortisol levels during early embryonic development on immune function in zebrafish (Danio rerio) larvae. Fertilized eggs were exposed to either a cortisol-containing, a dexamethasone-containing (to stimulate the glucocorticoid receptor selectively) or a control medium for 6 h post-fertilization (0-6 hpf). First, we measured baseline expression of a number of immune-related genes (socs3a, mpeg1.1, mpeg1.2, and irg1l) 5 days post-fertilization (dpf) in larvae of the AB and TL strain to assess the effectiveness of our exposure procedure and potential strain differences. Cortisol and dexamethasone strongly up-regulated baseline expression of these genes independent of strain. The next series of experiments were therefore carried out in larvae of the AB strain only. We measured neutrophil/macrophage recruitment following tail fin amputation (performed at 3 dpf) and phenotypical changes as well as survival following LPS-induced sepsis (150 µg/ml; 4-5 dpf). Dexamethasone, but not cortisol, exposure at 0-6 hpf enhanced neutrophil recruitment 4 h post tail fin amputation. Cortisol and dexamethasone exposure at 0-6 hpf led to a milder phenotype (e.g., less tail fin damage) and enhanced survival following LPS challenge compared to control exposure. Gene-expression analysis showed accompanying differences in transcript abundance of tlr4bb, cxcr4a, myd88, il1β, and il10. These data show that early-life exposure to cortisol, which may be considered to be a model or proxy of maternal stress, induces an adaptive response to immune challenges, which seems mediated via the glucocorticoid receptor.
The Protection of Personal Information Act (POPIA) 2013 came into force in South Africa on 1 July 2020. It seeks to strengthen the processing of personal information, including health information. While POPIA is to be welcomed, there are concerns about the impact it will have on the processing of health information. To ensure that the National Health Laboratory Service [NHLS] is compliant with these new strict processing requirements and that compliance does not negatively impact upon its current screening, treatment, surveillance and research mandate, it was decided to consider the development of a NHLS POPIA Code of Conduct for Personal Health. As part of the process of developing such a Code and better understand the challenges faced in the processing of personal health information in South Africa, 19 semi-structured interviews with stakeholders were conducted between June and September 2020. Overall, respondents welcomed the introduction of POPIA. However, they felt that there are tensions between the strengthening of data protection and the use of personal information for individual patient care, treatment programmes, and research. Respondents reported a need to rethink the management of personal health information in South Africa and identified 5 issues needing to be addressed at a national and an institutional level: an understanding of the importance of personal information; an understanding of POPIA and data protection; improve data quality; improve transparency in data use; and improve accountability in data use. The application of POPIA to the processing of personal health information is challenging, complex, and likely costly. However, personal health information must be appropriately managed to ensure the privacy of the data subject is protected, but equally that it is used as a resource in the individual’s and wider public interest.
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