Presence and genetic variability of Piscine orthoreovirus genotype 1 (PRV-1) in wild salmonids in Northern Europe and North Atlantic Ocean

Piscine orthoreovirus genotype 1 (PRV-1) is widespread in farmed Atlantic salmon (Salmo salar L.) populations in northern Europe, Canada and Chile. PRV-1 occurs in wild fish in Norway and Canada; however, little information of its geographical distribution in wild populations is currently available, and the effect of PRV-1 infection in wild populations is currently unknown. In this study, we present the findings of a survey conducted on 1,130 wild salmonids sampled in Denmark, Sweden, Ireland, Faroe Islands, France, Belgium and Greenland between 2008 and 2017. PRV-1 is reported for the first time in wild salmonids in Denmark, Sweden, Faroe Island and Ireland. The annual PRV-1 prevalence ranged from 0% in France, Belgium and Greenland to 43% in Faroe Islands. In total, 66 samples tested positive for PRV-1, including Atlantic salmon broodfish returning to spawn and Atlantic salmon collected at the feeding ground north of Faroe Islands. The phylogenetic analysis of S1 sequences of the PRV-1 isolates obtained in this survey did not show systematic geographical distribution. This study sheds light on the spread and genetic diversity of the virus identified in populations of free-living fish and provides rationale for screening wild broodfish used in restocking programmes.

Otolith shape: a population marker for Atlantic herring Clupea harengus

Otolith shape variation of seven Atlantic herring Clupea harengus populations from Canada, the Faroe Islands, Iceland, Ireland, Norway and Scotland, U.K., covering a large area of the species' distribution, was studied in order to see if otolith shape can be used to discriminate between populations. The otolith shape was obtained using quantitative shape analysis, transformed with Wavelet and analysed with multivariate methods. Significant differences were detected among the seven populations, which could be traced to three morphological structures in the otoliths. The differentiation in otolith shape between populations was not only correlated with their spawning time, indicating a strong environmental effect, but could also be due to differing life-history strategies. A model based on the shape differences discriminates with 94% accuracy between Icelandic summer spawners and Norwegian spring spawners, which are known to mix at feeding grounds. This study shows that otolith shape could become an accurate marker for C. harengus population discrimination.

Effect of antenatal exposure to paroxetine (paxil) on growth and physical maturation of mice offspring

OBJECTIVE

Our purpose was to determine, in a placebo-controlled manner, whether antenatal exposure to paroxetine affected long-term growth and physical maturation of mice offspring.

METHODS

Forty-one CD-1 mice consumed paroxetine (n = 21) or a placebo (n = 20) for 2 weeks before conception and throughout gestation. The daily dose of paroxetine (Paxil; 30 mg/kg/d) was known to achieve concentrations in the serum equivalent to the upper therapeutic level in humans and in the fetal brain equivalent to that of the adult mouse. Growth and physical maturation of the offspring were compared by paired t-test, Welch's corrected test, and Fisher's exact test.

RESULTS

The maternal weight gain, litter sizes, number of fetal resorptions, and gestational age at delivery were not different between the paroxetine and the placebo-exposed offspring. Newborn pups exposed to paroxetine were more likely to have low birthweights (1.65 gm vs. 1.70 gm; P < 0.05) and narrower heads (7.7 mm vs. 8.1 mm; P < 0.05). Body weight, body length, and head circumference measurements increased in a manner that was indistinguishable between the two groups of offspring, regardless of gender. No differences in achievement of physical milestones (lower incisor eruption, eye opening, and development of external genitalia) were noted between the two groups. The reproductive capability and the perinatal outcomes of the second-generation offspring were unaffected by paroxetine exposure.

CONCLUSION

A clinically relevant dose of paroxetine, when given throughout gestation, did not affect long-term growth and physical maturation of mice offspring.

TBT in marine sediments and blue mussels (Mytilus edulis) from central-west Greenland

Concentrations of butyltin compounds were investigated in the bivalve Mytilus edulis (five sites) and marine sediments (three sites) near the largest town, Nuuk, in Greenland. In seven of the eight samples the extremely toxic compound tributyltin (TBT) was detected. The concentrations of tributyltin and degradation products in the bivalves were close to 1 microgram kg-1 wet weight (ww), calculated as Sn, which is lower than those found in Iceland and the Faeroe Islands. In sediments the concentration of TBT ranged from below the limit of detection of 1 microgram kg-1 to 171 micrograms kg-1 dry weight (dw), calculated as Sn, which is comparable to levels found in Europe.

The efficacy of ivermectin (pour-on) against the eyeworms, Thelazia gulosa and Thelazia skrjabini in naturally infected cattle

Sixteen crossbred beef cattle, 6-8 months of age, were used to determine the efficacy of ivermectin in a pour-on formulation against natural infections of Thelazia spp. Cattle were weighed on Day 0, ranked in descending order by bodyweight and sequentially paired. Within each pair, one animal was randomly assigned to an untreated control group, while the other animal was treated with a pour-on formulation of ivermectin applied topically at 1.0 ml per 10 kg bodyweight to achieve a dosage of 500 mg ivermectin kg-1 body weight. On Day 14 all animals in both treatment groups were slaughtered. The eyes and surrounding tissues were removed and examined for eyeworms. A total of 86 adult worms (74 Thelazia skrjabini and 12 Thelazia gulosa) were recovered from the untreated control animals. T. skrjabini was found in seven, and T. gulosa in three, of the eight untreated control animals. Two T. skrjabini, one from each of two animals, were found on the surface of the eyes of cattle that had received ivermectin treatment. The reduction in the geometric mean number for T. gulosa collected from treated animals was 100% (P > 0.1) relative to controls, and 97.02% (P = 0.0025) for T. skrjabini relative to controls.