Environmental enrichment and its effects on telencephalic neurogenesis and behaviour in isolated adult zebrafish, Danio rerio

Adult neurogenesis has been subject to increasing interest over the past decades. In fish, this ability to create new neurons is impressive compared to most other vertebrate taxa. Several factors are known to influence adult neurogenesis, like environmental enrichment, learning, exercise, stress and aging. In this study, zebrafish were isolated and exposed to two different environments, a barren environment (control group) and an enriched environment (enriched group). The enriched environment was aquaria supplied with gravel and plastic plants, while the barren aquaria were left empty. Neurogenesis in the zebrafish was determined by proliferating cell nuclear antigen (PCNA) – immunohistochemistry. After development of a suitable protocol, this method gave staining of a quality that allowed quantification of stained nuclei in the telencephalic tissue. Number of PCNA positive cells per telencephalic volume, response time to distributed food, locomotion activity, cortisol levels and growth rate were measured and compared between the groups. Environmental enrichment led to a strong tendency towards higher neurogenesis, which is in concert with several studies performed of mammals. Also, a significantly higher inter-individual variation in number of new telencephalic cells was observed in the enriched group, indicating that heterogenic environments leads to greater heterogeneity in neurogenesis within a population. Response time to the distributed food was not significantly different between the groups, although the enriched group tended to have longer response time. The control group had significantly higher locomotor activity than the enriched group. In both experimental groups, the effect of time was significant and led to a decrease in both response time and locomotor activity. Whole-body cortisol levels were significantly higher in the enriched group, although this was likely an effect of longer capture time in this environment. This is the first study to examine environmental enrichment and its effects on neurogenesis and behaviour in zebrafish

Direct and indirect effects of sex steroids on gonadotrope cell plasticity in the teleost fish pituitary

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Gnrh receptor gnrhr2bbα is expressed exclusively in lhb-expressing cells in Atlantic salmon male parr

Gonadotropin-releasing hormone (Gnrh) plays a major role in the regulation of physiological and behavioural processes related to reproduction. In the pituitary, it stimulates gonadotropin synthesis and release via activation of Gnrh receptors (Gnrhr), belonging to the G protein-coupled receptor superfamily. Evidence suggests that differential regulation of the two gonadotropins (Fsh and Lh) is achieved through activation of distinct intracellular pathways and, probably, through the action of distinct receptors. However, the roles of the different Gnrhr isoforms in teleosts are still not well understood. This study investigates the gene expression of Gnrhr in the pituitary gland of precociously maturing Atlantic salmon (Salmo salar) male parr. A total of six Gnrhr paralogs were identified in the Atlantic salmon genome and named according to phylogenetic relationship; gnrhr1caα, gnrhr1caβ, gnrhr1cbα, gnrhr1cbβ, gnrhr2bbα, gnrhr2bbβ. All paralogs, except gnrhr1caα, were expressed in male parr pituitary during gonadal maturation as evidenced by qPCR analysis. Only one gene, gnrhr2bbα, was differentially expressed depending on maturational stage (yearly cycle), with high expression levels in maturing fish, increasing in parallel with gonadotropin subunit gene expression. Additionally, a correlation in daily expression levels was detected between gnrhr2bbα and lhb (daily cycle) in immature fish in mid-April. Double fluorescence in situ hybridization showed that gnrhr2bbα was expressed exclusively in lhb gonadotropes in the pituitary, with no expression detected in fshb cells. These results suggest the involvement of receptor paralog gnrhr2bbα in the regulation of lhb cells, and not fshb cells, in sexually maturing Atlantic salmon male parr.publishedVersio

A Multi-Site Assessment of Anesthetic Overdose, Hypothermic Shock, and Electrical Stunning as Methods of Euthanasia for Zebrafish (Danio rerio) Embryos and Larvae

17 pages, 6 figures, 4 tables.-- This is an open access article distributed under the Creative Commons Attribution LicenseEuthanasia in zebrafish (Danio rerio) younger than 5 days post fertilization (dpf) is poorly described in the literature, and standardized protocols are lacking, most likely because larvae not capable of independent feeding are often not protected under national legislations. We assessed the euthanasia efficacy in laboratories in different countries of a one hour anesthetic overdose immersion with buffered lidocaine hydrochloride (1 g/L, with or without 50 mL/L of ethanol), buffered tricaine (1 g/L), clove oil (0.1%), benzocaine (1 g/L), or 2-phenoxyethanol (3 mL/L), as well as the efficacy of hypothermic shock (one hour immersion) and electrical stunning (for one minute), on zebrafish at <12 h post fertilization (hpf), 24 hpf, and 4 dpf. Based on the survival/recovery rates 24 h after treatment, the most effective methods were clove oil, lidocaine with ethanol, and electrical stunning. For 4 dpf larvae, signs of aversion during treatment demonstrated that all anesthetics, except lidocaine, induced aversive behavior. Therefore, the most suited euthanasic treatment was lidocaine hydrochloride 1 g/L, buffered with 2 g/L of sodium bicarbonate and mixed with 50 mL/L of ethanol, which euthanized both embryos and larvae in an efficient and stress-free manner. Electrical stunning also euthanized embryos and larvae efficiently and without signs of aversion; this method needs further assessment in other laboratories to draw firm conclusionsThis research was funded by the Francis Crick Institute, which receives its core funding from Cancer Research U.K., the U.K. Medical Research Council, and the Wellcome Trust. P.R.L. is funded by a Hallas-Møller Emerging Investigator grant from the Novo Nordisk FoundationPeer reviewe

Genome editing in food and feed production – implications for risk assessment. Scientific Opinion of the Scientific Steering Committee of the Norwegian Scientific Committee for Food and Environment

The Norwegian Scientific Committee for Food and Environment (VKM) initiated this work to examine the extent to which organisms developed by genome-editing technologies pose new challenges in terms of risk assessment. This report considers whether the risk assessment guidance on genetically modified organisms, developed by the European Food Safety Authority (EFSA), can be applied to evaluate potential risks of organisms developed by genome editing. Background Gene technology has allowed for the transfer of genes between organisms and species, and thereby to design altered genotypes with novel traits, i.e. GMOs. A new paradigm started in the early 2000s with the development of genome-editing techniques. Unlike traditional genetic modification techniques resulting in insertion of foreign DNA fragments at random locations in the genome, the new genome-editing techniques additionally open for a few single nucleotide edits or short insertions/deletions at a targeted site in an organism’s genome. These new techniques can be applied to most types of organisms, including plants, animals and microorganisms of commercial interest. An important question is how the novel, genome-edited organisms should be evaluated with respect to risks to health and the environment. The European Court of Justice decided in 2018 to include genome-edited organisms in the GMO definition and hence in the regulatory system already in place. This implies that all products developed by genome-editing techniques must be risk-assessed within the existing regulatory framework for GMOs. The European and Norwegian regulatory frameworks regulate the production, import and placing on the market of food and feed containing, consisting of or produced from GMOs, as well as the release of GMOs into the environment. The assessment draws on guidance documents originally developed by EFSA for risk assessment of GMOs, which were drawn up mainly to address risks regarding insertion of transgenes. The new genome-editing techniques, however, provide a new continuum of organisms ranging from those only containing a minor genetic alteration to organisms containing insertion or deletion of larger genomic regions. Risk assessment of organisms developed by genome editing The present discourse on how new genome-editing techniques should be regulated lacks an analysis of whether risk assessment methodologies for GMOs are adequate for risk assessment of organisms developed through the use of the new genome-editing techniques. Therefore, this report describes the use of genome-editing techniques in food and feed production and discusses challenges in risk assessment with the regulatory framework. Specifically, this report poses the question as to whether the EFSA guidance documents are sufficient for evaluating risks to health and environment posed by genome-edited plants, animals and microorganisms. To address these questions, the report makes use of case examples relevant for Norway. These examples, intended for food and feed, include oilseed rape with a modified fatty acid profile, herbicide-tolerant and pest-resistant crops, sterile salmon, virus-resistant pigs and hornless cattle. The report considers all aspects of the stepwise approach as described in the EFSA guidance documents. Conclusions The inherent flexibility of the EFSA guidance makes it suitable to cover health and environmental risk assessments of a wide range of organisms with various traits and intended uses. Combined with the embedded case-by-case approach the guidance is applicable to genome-edited organisms. The evaluation of the guidance demonstrates that the parts of the health and environmental risk assessment concerned with novel traits (i.e. the phenotype of the organism) may be fully applied to all categories of genome-edited organisms. ............acceptedVersionpublishedVersio

Genome editing in food and feed production – implications for risk assessment. Scientific Opinion of the Scientific Steering Committee of the Norwegian Scientific Committee for Food and Environment

The Norwegian Scientific Committee for Food and Environment (VKM) initiated this work to examine the extent to which organisms developed by genome-editing technologies pose new challenges in terms of risk assessment. This report considers whether the risk assessment guidance on genetically modified organisms, developed by the European Food Safety Authority (EFSA), can be applied to evaluate potential risks of organisms developed by genome editing. Background Gene technology has allowed for the transfer of genes between organisms and species, and thereby to design altered genotypes with novel traits, i.e. GMOs. A new paradigm started in the early 2000s with the development of genome-editing techniques. Unlike traditional genetic modification techniques resulting in insertion of foreign DNA fragments at random locations in the genome, the new genome-editing techniques additionally open for a few single nucleotide edits or short insertions/deletions at a targeted site in an organism’s genome. These new techniques can be applied to most types of organisms, including plants, animals and microorganisms of commercial interest. An important question is how the novel, genome-edited organisms should be evaluated with respect to risks to health and the environment. The European Court of Justice decided in 2018 to include genome-edited organisms in the GMO definition and hence in the regulatory system already in place. This implies that all products developed by genome-editing techniques must be risk-assessed within the existing regulatory framework for GMOs. The European and Norwegian regulatory frameworks regulate the production, import and placing on the market of food and feed containing, consisting of or produced from GMOs, as well as the release of GMOs into the environment. The assessment draws on guidance documents originally developed by EFSA for risk assessment of GMOs, which were drawn up mainly to address risks regarding insertion of transgenes. The new genome-editing techniques, however, provide a new continuum of organisms ranging from those only containing a minor genetic alteration to organisms containing insertion or deletion of larger genomic regions. Risk assessment of organisms developed by genome editing The present discourse on how new genome-editing techniques should be regulated lacks an analysis of whether risk assessment methodologies for GMOs are adequate for risk assessment of organisms developed through the use of the new genome-editing techniques. Therefore, this report describes the use of genome-editing techniques in food and feed production and discusses challenges in risk assessment with the regulatory framework. Specifically, this report poses the question as to whether the EFSA guidance documents are sufficient for evaluating risks to health and environment posed by genome-edited plants, animals and microorganisms. To address these questions, the report makes use of case examples relevant for Norway. These examples, intended for food and feed, include oilseed rape with a modified fatty acid profile, herbicide-tolerant and pest-resistant crops, sterile salmon, virus-resistant pigs and hornless cattle. The report considers all aspects of the stepwise approach as described in the EFSA guidance documents. Conclusions The inherent flexibility of the EFSA guidance makes it suitable to cover health and environmental risk assessments of a wide range of organisms with various traits and intended uses. Combined with the embedded case-by-case approach the guidance is applicable to genome-edited organisms. The evaluation of the guidance demonstrates that the parts of the health and environmental risk assessment concerned with novel traits (i.e. the phenotype of the organism) may be fully applied to all categories of genome-edited organisms. ............publishedVersio

Genome editing in food and feed production – implications for risk assessment. Opinion of the Steering Committee of the Norwegian Scientific Committee for Food and Environment

publishedVersio

Genome editing in food and feed production – implications for risk assessment

The Norwegian Scientific Committee for Food and Environment (VKM) initiated this work to examine the extent to which organisms developed by genome-editing technologies pose new challenges in terms of risk assessment. This report considers whether the risk assessment guidance on genetically modified organisms, developed by the European Food Safety Authority (EFSA), can be applied to evaluate potential risks of organisms developed by genome editing.acceptedVersio

Genome editing in food and feed production – implications for risk assessment. Opinion of the Steering Committee of the Norwegian Scientific Committee for Food and Environment

Source at https://vkm.no/I denne rapporten vurderer Vitenskapskomiteen for mat og miljø (VKM) utfordringer knyttet til helse- og miljørisikovurdering av genomredigerte organismer til mat- og fôrproduksjon. VKM har gått gjennom veiledningen for risikovurdering av genmodifiserte organismer (GMO) som Den europeiske myndighet for næringsmiddeltrygghet (EFSA) har utviklet, og vurdert om veiledningen også kan brukes til å vurdere risiko ved organismer som er utviklet ved genomredigering. VKM har selv tatt initiativ til denne rapporten.The Norwegian Scientific Committee for Food and Environment (VKM) initiated this work to examine the extent to which organisms developed by genome-editing technologies pose new challenges in terms of risk assessment. This report considers whether the risk assessment guidance on genetically modified organisms, developed by the European Food Safety Authority (EFSA), can be applied to evaluate potential risks of organisms developed by genome editing

Genome editing in food and feed production – implications for risk assessment

The Norwegian Scientific Committee for Food and Environment (VKM) initiated this work to examine the extent to which organisms developed by genome-editing technologies pose new challenges in terms of risk assessment. This report considers whether the risk assessment guidance on genetically modified organisms, developed by the European Food Safety Authority (EFSA), can be applied to evaluate potential risks of organisms developed by genome editing.acceptedVersio