Protection against Atlantic halibut nodavirus in turbot is induced by recombinant capsid protein vaccination but not following DNA vaccination

Fish nodaviruses (betanodaviruses) are small, non-enveloped icosahedral single-stranded positive-sense RNA viruses that can cause viral encephalopathy and retinopathy (VER) in a number of cultured marine teleost species, including Atlantic halibut (Hippoglossus hippoglossus). A recombinant protein vaccine and a DNA vaccine were produced, based on the same capsid-encoding region of the Atlantic halibut nodavirus (AHNV) genome, and tested for protection in juvenile turbot (Scophthalmus maximus). Vaccine efficacy was demonstrated in the fish vaccinated with recombinant capsid protein but not in the DNA-vaccinated fish, despite the fact that in vivo expression of the DNA vaccine-encoded antigen was confirmed by RNA in situ hybridisation and immunohistochemistry. Combined DNA and recombinant vaccine administration did not improve the effect of the latter. Surprisingly, fish vaccinated with 50 microg recombinant protein demonstrated a threefold lower survival rate than the two groups that received 10 microg recombinant protein. Neither the recombinant protein vaccine nor the DNA vaccine induced anti-viral antibodies 9 weeks after immunisation, while antibodies reactive with the recombinant protein were detectable mainly in fish vaccinated with 50 microg recombinant protein. The study also demonstrates evidence of viral replication inside the myocytes of intramuscularly challenged fish.     

Epitope mapping of pneumococcal surface protein A of strain Rx1 using monoclonal antibodies and molecular structure modelling

Pneumococcal surface protein A (PspA) is an antigenic variable vaccine candidate of Streptococcus pneumoniae. Epitope similarities between PspA from the American vaccine candidate strain Rx1 and Norwegian clinical isolates were studied using PspA specific monoclonal antibodies (mAbs) made against clinical Norwegian strains. Using recombinant PspA/Rx1 fragments and immunoblotting the epitopes for mAbs were mapped to two regions of amino acids, 1-67 and 67-236. The discovered epitopes were visualized by modelling of the PspA:Fab part of mAb in three dimensions. Flow cytometric analysis showed that the epitopes for majority of mAbs were accessible for antibody binding on live pneumococci. Also, the epitopes for majority of the mAbs are widely expressed among clinical Norwegian isolates.     

Keeping close to the river,shore and surface: the first marine migration of brown trout (Salmo trutta) and Arctic charr (Salvelinus alpinus) post-smolts

Acoustic telemetry was utilized to track 49 brown trout (Salmo trutta) and 37 Arctic charr (Salvelinus alpinus) first-time migrants of wild origin [post-smolts; mean L_F (fork length): 169 and 172 mm] in a large fjord in northern Norway. The S. trutta were registered at sea for more than twice the time of the S. alpinus (medians of 54 and 22 days, respectively). Both species were mostly detected near river mouths (>80% of detections) and almost exclusively spent their time (>95%) within the interior 18 km of the fjord. They were surface oriented, with most detections at <1 m depth and S. trutta deeper on average (median mean depths of 0.7 and 0.5 m, respectively). This study concludes that post-smolts of both species stay closer to the surface and to river mouths than larger veteran migrants. This study emphasizes the importance of river mouths and upper water layers for the survival of both species during their first marine migration.     

A deep dive into fat: Investigating blubber lipidomic fingerprint of killer whales and humpback whales in northern Norway

In cetaceans, blubber is the primary and largest lipid body reservoir. Our current understanding about lipid stores and uses in cetaceans is still limited, and most studies only focused on a single narrow snapshot of the lipidome. We documented an extended lipidomic fingerprint in two cetacean species present in northern Norway during wintertime. We were able to detect 817 molecular lipid species in blubber of killer whales (Orcinus orca) and humpback whales (Megaptera novaeangliae). The profiles were largely dominated by triradylglycerols in both species and, to a lesser extent, by other constituents including glycerophosphocholines, phosphosphingolipids, glycerophosphoethanolamines, and diradylglycerols. Through a unique combination of traditional statistical approaches, together with a novel bioinformatic tool (LION/web), we showed contrasting fingerprint composition between species. The higher content of triradylglycerols in humpback whales is necessary to fuel their upcoming half a year fasting and energy‐demanding migration between feeding and breeding grounds. In adipocytes, we assume that the intense feeding rate of humpback whales prior to migration translates into an important accumulation of triacylglycerol content in lipid droplets. Upstream, the endoplasmic reticulum is operating at full capacity to supply acute lipid storage, consistent with the reported enrichment of glycerophosphocholines in humpback whales, major components of the endoplasmic reticulum. There was also an enrichment of membrane components, which translates into higher sphingolipid content in the lipidome of killer whales, potentially as a structural adaptation for their higher hydrodynamic performance. Finally, the presence of both lipid‐enriched and lipid‐depleted individuals within the killer whale population in Norway suggests dietary specialization, consistent with significant differences in δ¹⁵N and δ¹³C isotopic ratios in skin between the two groups, with higher values and a wider niche for the lipid‐enriched individuals. Results suggest the lipid‐depleted killer whales were herring specialists, while the lipid‐enriched individuals might feed on both herrings and seals.     

Effect of genetic polymorphisms involved in folate metabolism on the concentration of serum folate and plasma total homocysteine (p-tHcy) in healthy subjects after short-term folic acid supplementation: a randomized,double blind,crossover study

Data on the effect of combined genetic polymorphisms, involved in folate metabolism, on the concentration of serum folate after folic acid supplementation are scarce. Therefore, we investigated the impact of seven gene polymorphisms on the concentration of serum folate and p-tHcy in healthy subjects after short-term folic acid supplementation. In a randomized, double blind, crossover study, apparently healthy subjects were given either 0.8 mg folic acid per day (n = 46) or placebo (n = 45) for 14 days. The washout period was 14 days. Fasting blood samples were collected on day 1, 15, 30 and 45. Data on subjects on folic acid supplementation (n = 91) and on placebo (n = 45) were used for the statistical analysis. The concentration of serum folate increased higher in subjects with higher age (53.5 ± 7.0 years) than in subjects with lower age (24.3 ± 3.2 years) after folic acid supplementation (p = 0.006). The baseline concentration of serum folate in subjects with polymorphism combination, reduced folate carrier protein, RFC1-80 GA and methylenetetrahydrofolate reductase, MTHFR677 CT+TT, was lower than RFC1-80 AA and MTHFR677 CT+TT (p = 0.002). After folic acid supplementation, a higher increase in the concentration of serum folate was detected in subjects with polymorphism combination RFC1-80 GA and MTHFR677 CC than RFC1-80 GG and MTHFR CT+TT combination (p < 0.0001). The baseline concentration of plasma total homocysteine (p-tHcy) was altered by combined polymorphisms in genes associated with folate metabolism. After folic acid supplementation, in subjects with combined polymorphisms in methylenetetrahydrofolate dehydrogenase, MTHFD1-1958 and MTHFR-677 genes, the concentration of p-tHcy was changed (p = 0.002). The combination of RFC1-80 and MTHFR-677 polymorphisms had a profound affect on the concentration of serum folate in healthy subjects before and after folic acid supplementation.     

Plastic reproductive allocation as a buffer against environmental stochasticity – linking life history and population dynamics to climate

Empirical work suggest that long‐lived organisms have adopted risk sensitive reproductive strategies where individuals trade the amount of resources spent on reproduction versus survival according to expected future environmental conditions. Earlier studies also suggest that climate affects population dynamics both directly by affecting population vital rates and indirectly through long‐term changes in individual life histories. Using a seasonal and state‐dependent individual‐based model we investigated how environmental variability affects the selection of reproductive strategies and their effect on population dynamics. We found that: (1) dynamic, i.e. plastic, reproductive strategies were optimal in a variable climate. (2) Females in poor and unpredictable climatic regimes allocated fewer available resources in reproduction and more in own somatic growth. This resulted in populations with low population densities, and a high average female age and body mass. (3) Strong negative density dependence on offspring body mass and survival, along with co‐variation between climatic severity and population density, resulted in no clear negative climatic effects on reproductive success and offspring body mass. (4) Time series analyses of population growth rates revealed that populations inhabiting benign environments showed the clearest response to climatic perturbations as high population density prohibited an effective buffering of adverse climatic effects as individuals were not able to gain sufficient body reserves during summer. Regularly occurring harsh winters ‘harvested’ populations, resulting in persistent low densities, and released them from negative density dependent effects, resulting in high rewards for a given resource allocation.     

Life table parameters and capture success ratio studies of Typhlodromips swirskii (Acari: Phytoseiidae) to the factitious prey Suidasia medanensis (Acari: Suidasidae)

The predatory mite Typhlodromips swirskii (Athias–Henriot) is commonly used to suppress pest populations of thrips and whitefly in commercial greenhouses. Many generalist phytoseiid mites can be reared on astigmatid factitious prey. This study investigated the life table parameters of T. swirskii to the astigmatid mite Suidasia medanensis (Oudemans) and the capture success ratio of T. swirskii to different life stages of the prey. Juvenile development time and survival was 5.01 ± 0.10 days and 93 %, respectively. The intrinsic (r _m ) and finite (λ) rates of increase were 0.222 and 1.249, respectively, with average oviposition rate of 1.71 ± 0.07 eggs/female/day. The capture success ratio of T. swirskii to S. medanensis was: eggs > freeze killed adults > nymphs > live adults. Typhlodromips swirskii was concluded to exhibit good population growth rates with S. medanensis as prey and, a prey population with predominance of eggs and nymphs to be advantageous to the predator due to an unidentified defence mechanism of adult prey.