Reduced physiological plasticity in a fish adapted to stable temperatures

Publisher Copyright: Copyright © 2022 the Author(s).Plasticity can allow organisms to maintain consistent performance across a wide range of environmental conditions. However, it remains largely unknown how costly plasticity is and whether a trade-off exists between plasticity and performance under optimal conditions. Biological rates generally increase with temperature, and to counter that effect, fish use physiological plasticity to adjust their biochemical and physiological functions. Zebrafish in the wild encounter large daily and seasonal temperature fluctuations, suggesting they should display high physiological plasticity. Conversely, laboratory zebrafish have been at optimal temperatures with low thermal fluctuations for over 150 generations. We treated this domestication as an evolution experiment and asked whether this has reduced the physiological plasticity of laboratory fish compared to their wild counterparts. We measured a diverse range of phenotypic traits, from gene expression through physiology to behavior, in wild and laboratory zebrafish acclimated to 15 temperatures from 10 °C to 38 °C. We show that adaptation to the laboratory environment has had major effects on all levels of biology. Laboratory fish show reduced plasticity and are thus less able to counter the direct effects of temperature on key traits like metabolic rates and thermal tolerance, and this difference is detectable down to gene expression level. Rapid selection for faster growth in stable laboratory environments appears to have carried with it a trade-off against physiological plasticity in captive zebrafish compared with their wild counterparts.Peer reviewe

C-reactive protein and complement as acute phase reactants in common carp Cyprinus carpio during CyHV-3 infection

Cyprinid herpesvirus 3 (CyHV-3) is the aetiological agent of a highly virulent and lethal disease of common carp Cyprinus carpio and its ornamental koi varieties. However, specific knowledge about immune mechanisms behind the infection process is very limited. We aimed to evaluate the effect of the CyHV-3 infection on the profile of 2 major components of the common carp immune acute phase response: the C-reactive protein (CRP) and the complement system. Common carp were infected with CyHV-3 by bath immersion. Fish were sampled before the infection and at 6, 12, 24, 72, 120 and 336 h post-infection for serum and head kidney, liver, gill and spleen tissues. CRP levels and complement activity were determined from the serum, whereas CRP- and complement-related genes (crp1, crp2, c1rs, bf/c2, c3, masp2) expression profiles were analysed in the tissues by quantitative PCR. Both CRP levels and complement activity increased significantly up to 10- and 3-fold, respectively, in the serum of infected fish during the challenge. Analysis revealed distinct organ- and time-dependent expression profile patterns for all selected genes. These results suggest that CRP and complement behave as acute phase reactants to CyHV-3 infection in common carp with an organ- and time-dependent response

Feeding common carp Cyprinus carpio with b-glucan supplemented diet stimulates C-reactive protein and complement immune acute phase responses following PAMPs injection

The effect of β-glucan as a feed additive on the serum and gene profile of C-reactive protein (CRP) and complement acute phase responses was ascertained in common carp Cyprinus carpio. In addition effects of subsequent intraperitoneal injections of pathogen-associated molecular patterns (PAMPs), i.e. LPS or poly(I:C), to mimic bacterial or viral infection respectively, were studied. Carp were first orally fed with β-glucan (MacroGard®) with a daily β-glucan intake of 6 mg per kg body weight or with control food for 25 days and then injected with PBS containing either LPS (4 mg/kg) or poly(I:C) (5 mg/kg) or PBS alone. Fish were sampled during the 25 days of the feeding period and up to 7 days post-PAMPs injections for serum and liver, head kidney and mid-gut tissues. Oral administration of β-glucan for 25 days significantly increased serum CRP levels and alternative complement activity (ACP). In addition, the subsequent LPS and poly(I:C) challenges significantly affected CRP and complement related gene expression profiles (crp1, crp2, c1r/s, bf/c2, c3 and masp2), with the greatest effects observed in the β-glucan fed fish. However, in fish fed β-glucan the PAMPs injections had less effects on CRP levels and complement activity in the serum than in control fed fish, suggesting that the 25 days of β-glucan immunostimulation was sufficient enough to reduce the effects of LPS and poly(I:C) injections. Results suggest that MacroGard® stimulated CRP and complement responses to PAMPs immunological challenges in common carp thus highlighting the beneficial β-glucan immunostimulant properties

The Korowai Framework: Assessing GE through the Values the ART Confederation Associates with Ngarara

The aim of this thesis is to assess genetic engineering (GE) through the values that the Confederation of Te Ati Awa, Ngati Raukawa ki te tonga and Ngati Toarangatira (the ART Confederation) associates with ngarara. The Korowai Framework was developed to conduct this assessment. Interviews were conducted with 14 participants from across the ART Confederation on the values they associate with ngarara and their interpretations of GE. The values associated with ngarara that were identified in the interviews, were used constitute the kaupapa of the Korowai Framework. The key values identified are: mauri, whakapapa, tohu, tapu, and kaitiakitanga. It emerged from the interviews that ngarara appeal to us to be conscious of our intricately bound connection to and dependency on living systems. The assessment through the Korowai Framework found that the outcomes of GE do not uphold the values associated with ngarara. Participants articulated significant concerns that GE confounds the ART Confederation's control over their relationship with the world around them. This thesis has demonstrated that the Korowai Framework can be used as a tool for the Confederation to get to the decision making table with a comprehensive evidence based understanding of the people's position on GE from which they can negotiate. It demonstrates that robust and legitimate assessment of GE can be conducted using theories, methodologies, kaupapa, tikanga, and frameworks that are specific to the ART Confederation

Differential effects of Alloherpesvirus CyHV-3 and Rhabdovirus SVCV on apoptosis in fish cells

Whilst Herpesviridae, which infect higher vertebrates, actively influence host immune responses to ensure viral replication, it is mostly unknown if Alloherpesviridae, which infect lower vertebrates, possess similar abilities. An important antiviral response is clearance of infected cells via apoptosis, which in mammals influences the outcome of infection. Here, we utilise common carp infected with CyHV-3 to determine the effect on the expression of genes encoding apoptosis-related proteins (p53, Caspase 9, Apaf-1, IAP, iNOS) in the pronephros, spleen and gills. The influence of CyHV-3 on CCB cells was also studied and compared to SVCV (a rhabdovirus) which induces apoptosis in carp cell lines. Although CyHV-3 induced iNOS expression in vivo, significant induction of the genetic apoptosis pathway was only seen in the pronephros. In vitro CyHV-3 did not induce apoptosis or apoptosis-related expression whilst SVCV did stimulate apoptosis. This suggests that CyHV-3 possesses mechanisms similar to herpesviruses of higher vertebrates to inhibit the antiviral apoptotic process

Dietary b-glucan (MacroGard®) enhances survival of first feeding turbot (Scophthalmus maximus) larvae by altering immunity, metabolism and microbiota

Reflecting the natural biology of mass spawning fish aquaculture production of fish larvae is often hampered by high and unpredictable mortality rates. The present study aimed to enhance larval performance and immunity via the oral administration of an immunomodulator, β-glucan (MacroGard®) in turbot (Scophthalmus maximus). Rotifers (Brachionus plicatilis) were incubated with or without yeast β-1,3/1,6-glucan in form of MacroGard® at a concentration of 0.5 g/L. Rotifers were fed to first feeding turbot larvae once a day. From day 13 dph onwards all tanks were additionally fed untreated Artemia sp. nauplii (1 nauplius ml/L). Daily mortality was monitored and larvae were sampled at 11 and 24 dph for expression of 30 genes, microbiota analysis, trypsin activity and size measurements. Along with the feeding of β-glucan daily mortality was significantly reduced by ca. 15% and an alteration of the larval microbiota was observed. At 11 dph gene expression of trypsin and chymotrypsin was elevated in the MacroGard® fed fish, which resulted in heightened tryptic enzyme activity. No effect on genes encoding antioxidative proteins was observed, whilst the immune response was clearly modulated by β-glucan. At 11 dph complement component c3 was elevated whilst cytokines, antimicrobial peptides, toll like receptor 3 and heat shock protein 70 were not affected. At the later time point (24 dph) an anti-inflammatory effect in form of a down-regulation of hsp 70, tnf-α and il-1β was observed. We conclude that the administration of MacroGard® induced an immunomodulatory response and could be used as an effective measure to increase survival in rearing of turbot

Molecular ontogeny of larval immunity in European eel at increasing temperatures

Temperature is a major factor that modulates the development and reactivity of the immune system. Only limited knowledge exists regarding the immune system of the catadromous European eel, Anguilla anguilla, especially during the oceanic early life history stages. Thus, a new molecular toolbox was developed, involving tissue specific characterisation of 3 housekeeping genes, 9 genes from the innate and 3 genes from the adaptive immune system of this species. The spatial pattern of immune genes reflected their function, e.g. complement component c3 was mainly produced in liver and il10 in the head kidney. Subsequently, the ontogeny of the immune system was studied in larvae reared from hatch to first-feeding at four temperatures, spanning their thermal tolerance range (16, 18, 20, and 22 °C). Expression of some genes (c3 and igm) declined post hatch, whilst expression of most other genes (mhc2, tlr2, il1β, irf3, irf7) increased with larval age. At the optimal temperature, 18 °C, this pattern of immune-gene expression revealed an immunocompromised phase between hatch (0 dph) and teeth-development (8 dph). The expression of two of the studied genes (mhc2, lysc) was temperature dependent, leading to increased mRNA levels at 22 °C. Additionally, at the lower end of the thermal spectrum (16 °C) immune competency appeared reduced, whilst close to the upper thermal limit (22 °C) larvae showed signs of thermal stress. Thus, protection against pathogens is probably impaired at temperatures close to the critical thermal maximum (CTmax), impacting survival and productivity in hatcheries and natural recruitment