Effect of fish length and nutritional condition on the fecundity of distressed Atlantic cod Gadus morhua from the Baltic Sea

The disappearance of larger individuals and the decrease in individual body condition suffered by Atlantic cod Gadus morhua in the eastern Baltic during the past two decades can be expected to affect the stock reproductive output. To investigate this, female G. morhua were collected during the spawning and pre-spawning period in 2015-2016. The current individual potential fecundity (F_P ) of eastern Baltic G. morhua was estimated and analysed in relation to total length (L_T ) and indices of nutritional status such as body condition (K) and hepato-somatic index (I_H ) using generalized linear models. In addition, the current prevalence of atresia and its potential relation to K were investigated. Moreover, a calibration curve to estimate F_P from oocyte diameter, based on the autodiametric oocyte counting method, was established for the first time for eastern Baltic G. morhua and can be used for future fecundity studies on this stock. The results showed that F_P was mainly positively related to fish length, but K and I_H also contributed significantly to the variation in F_P . The model predicted that fish with K = 1·2 have a F_P 51% higher than fish of the same L_T with K = 0·8. The prevalence of fecundity regulation by atresia was 5·8%, but it was found only in fish in the pre-spawning maturity stage and with low K. Temporal changes in biological features such as the length composition and individual body condition of eastern Baltic G. morhua, should be accounted for when estimating stock reproductive potential.

Water temperature and dietary histidine affect cataract formation in Atlantic salmon (Salmo salar L.) diploid and triploid yearling smolt

The aim of the present study was to investigate cataract development in diploid (2N) and triploid (3N) Atlantic salmon smolts and post-smolts at two water temperatures (10 and 16 °C) given diets with different histidine supplementation (LH, 10.4 and HH, 13.1 g kg^-1 ) before and after seawater transfer. In freshwater, a severe cataract outbreak was recorded in both ploidies reared at 16 °C. The cataract score was significantly higher in triploids compared to diploids, and the severity was lower in both ploidies fed the HH diet. The cataract development at 10 °C was minor. Low gill Na⁺ , K⁺ -ATPase activity in fish reared at 16 °C before seawater transfer was followed by osmoregulatory stress with elevated plasma electrolyte concentrations and high mortality in sea water. Both diploids and triploids reared at 10 °C developed cataracts during the seawater period, with higher severities in triploids than diploids and a reduced severity in the fish fed the HH diet. The findings of this study demonstrate the importance of environmental conditions in the husbandry of Atlantic salmon, and particularly triploids, with regard to smoltification and adjusted diets to mitigate cataract development in fresh and sea water.

Fecundity regulation by atresia in turbot Scophthalmus maximus in the Baltic Sea

Down-regulation of fecundity through oocyte resorption was assessed in Baltic Sea turbot Scophthalmus maximus at three locations in the period from late vitellogenesis in April to spawning during June to July. The mean ± s.d. total length of the sampled fish was 32.7 ± 3.1 cm and mean ± s.d. age was 6.2 ± 1.5 years. Measurements of atresia were performed using the 'profile method' with the intensity of atresia adjusted according to the 'dissector method' (10.6% adjustment; coefficient of determination was 0.675 between methods). Both prevalence (portion of fish with atresia) and intensity (calculated as the average proportion of atretic cells in fish displaying atresia) of atresia were low in prespawning fish, but high from onset of spawning throughout the spawning period. Atretic oocytes categorized as in early alpha and in late alpha state occurred irrespective of maturity stage from late prespawning individuals up to late spawning fish, showing that oocytes may become atretic throughout the spawning period. Observed prevalence of atresia throughout the spawning period was almost 40% with an intensity of c. 20%. This indicates extensive down-regulation, i.e. considerably lower realized (number of eggs spawned) v. potential fecundity (number of developing oocytes), suggesting significant variability in reproductive potential. The extent of fecundity regulation in relation to fish condition (Fulton's condition factor) is discussed, suggesting an association between levels of atresia and fish condition.

The effect of dietary lipid content and stress on egg quality in farmed Atlantic cod Gadus morhua

The present study assessed differences in fecundity and egg quality from Atlantic cod Gadus morhua fed isoproteic diets containing 13% fat (low fat, LF) or 20% fat (high fat, HF) and either stressed or left unstressed as a control over the spawning season. Each diet was fed to triplicate groups of G. morhua from June 2009, through to first maturation and spawning. In January 2010 sub-groups of G. morhua were moved to land-based spawning tanks where the experimental trial was carried out. At the start of the experiment, G. morhua fed the high-fat diet were significantly larger than G. morhua fed low-fat diet. These differences were maintained through the spawning season, although with a loss of mass in both dietary groups. Relative fecundity through the season was significantly lower in stressed G. morhua fed LF compared to unstressed G. morhua fed the same diet. Stressed G. morhua had a higher variability in weekly amount of eggs spawned, spawning occurred more irregularly, and the spawning period lasted longer than in unstressed G. morhua. Several egg quality variables were also affected: eggs from G. morhua fed LF and exposed to stress had lower fertilization and hatching rates compared to the unstressed G. morhua fed the same diet as well as all G. morhua fed HF. Gadus morhua fed a low-fat diet appeared less tolerant to stress than fish fed a high-fat diet.

Effects of egg size, parental origin and feeding conditions on growth of larval and juvenile cod Gadus morhua

An experimental study was performed to disentangle parental and environmental effects on the growth of Atlantic cod Gadus morhua larvae and juveniles. Eggs were collected during the spawning season from spawning pairs (families) kept separately in specially designed spawning compartments. Newly hatched larvae were released simultaneously into two mesocosms of 2,500 and 4,400 m(3). Larval growth was monitored by sampling over a 10 week period, after which juveniles were transferred to on-growing tanks, where they were tagged and kept for up to 2 years. Maternal origin was determined by individual microsatellite genotyping of the larvae (n = 3949, 24 families) and juveniles (n = 600). The results showed significant positive correlations between egg size and larval size during the whole mesocosm period. Correlations, however, weakened with time and were no longer significant at the first tank-rearing sampling at an age of 9 months. Significant family-specific differences in growth were observed. The coefficient of variation (c.v.) was calculated in order to examine variation in standard length of larvae during the mesocosm period. Inter-family c.v. was on average 69% of intra-family c.v. Differences in zooplankton densities between the two mesocosms were reflected in larval growth, condition factor and c.v. Low food abundance appeared to reduce c.v. and favour growth of larvae that showed relatively slow growth at high food abundance. It is suggested that genetically determined variation in growth potential is maintained by environmental variability.

FDG imaging of a pulmonary artery sarcoma

Fluorine-18-2-fluro-2-deoxy-D-glucose-positron emission tomographic tumor imaging was employed to aid in the diagnosis of a patient with a right hilar mass. Based on preoperative imaging and intraoperative findings, a right pneumonectomy was performed for what proved to be a pulmonary artery sarcoma.

Is there a role for abdominal computed tomographic scans in appendicitis?

OBJECTIVE

To better define the effectiveness of abdominal computed tomographic scanning (ACTS) in adult patients with suspected appendicitis.

DESIGN

Retrospective analysis.

SETTING

A community teaching hospital.

PATIENTS

Ninety-seven patients with appendicitis in the differential diagnosis, whose clinical findings were insufficient to perform surgery or to discharge from the hospital, during a 14-month period.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Accuracy of ACTS, rate of appendectomies that show no appendicitis (negative appendectomy rate), and frequency of ACTS as a definitive diagnostic test.

RESULTS

Forty-nine of the 50 patients with appendicitis were correctly diagnosed by ACTS. Forty-three of the 47 patients without appendicitis were correctly diagnosed by ACTS. Positive predictive value was 92%, negative predictive value was 98%, and accuracy was 96%. The ACTS group had a negative appendectomy rate of 5.8% (3/52), lower than the hospital rate of 14% for the preceding 3 years. The ACTS established an alternative diagnosis in 16 patients, allowed 10 other patients to be discharged early or not admitted, and was the critical diagnostic test in 30 of the patients with appendicitis. Therefore, the ACTS played a definitive role in the treatment of 56 (57.7%) of the 97 patients.

CONCLUSIONS

The ACTS was an accurate test in the diagnosis of appendicitis and was of significant benefit in 57.7% of the patients studied. However, it was difficult to predict which patients were most likely to benefit. Expanded selective use of ACTS for patients with clinically indeterminate appendicitis may result in a lower negative appendectomy rate and fewer patient admissions for observation.

Ethanol-induced formation of solid calcium phosphates

Conventional transmission electron microscopy requires an effective dehydration of the tissue specimens under investigation. This dehydration, for which ethanol most often is used, may influence the solubility of the slightly soluble calcium phosphates. To study the behavior of calcium phosphates in ethanol, stable neutral aqueous solutions containing the ions were mixed with ethanol in various ratios at 20 degrees C. After 24 hours, the precipitates formed wee identified by x-ray diffraction to be either apatite, brushite, or amorphous calcium phosphate. The results are discussed with reference to possible formation of calcium phosphate artifacts.

A comparison of some effects of fluoride on apatite formation in vitro and in vivo

In a liquid (22 degrees C) saturated with and in contact with powdered bone apatite, the fluoride ion activity was adjusted to 1-10 parts/10(6). Due to the fluorapatite (FAP) supersaturation produced hereby, a rapid formation of this salt occurred leading to a decrease of the concentration of the ions involved. When no more fluoride was available in the liquid, the concentrations of calcium and phosphate increased again, due to dissolution of presumably hydroxyapatite (HAP). Fifty four rats were given either 10, 20, or 40 mg NaF per kg body weight intraperitoneally. The animals were sacrificed from 5 min to 96 h after the injection. The fluoride concentration in plasma increased to a peak, after which it decreased. Plasma calcium decreased and remained low until the fluoride had attained normal levels. The intensity of mineralization of the growing dental hard tissue was monitored on microradiographs. Corresponding to the plasma fluoride peak and the decrease of plasma calcium, a hypermineralized layer was formed while a hypomineralized zone was formed during plasma calcium increase after disappearance of fluoride. Similarities and dissimilarities between the in vitro and the in vivo experiments are discussed.

Calcium fluoride formation on enamel and its influence on uptake of fluoride in the apatitic lattice

Human dental enamel was exposed to a pH 4 buffer containing 150 parts/10(6) fluoride. It was found that due to the arising degrees of saturation with respect to calcium fluoride and apatites, surface enamel dissolved coincident with a formation of calcium fluoride. The calcium fluoride redissolved while it kept the liquid saturated with respect to this salt. During this second period, fluorapatite was formed while hydroxyapatite dissolved. Finally, all calcium fluoride was dissolved and the unreacted fluoride was taken up in the apatitic lattice. The results are discussed with reference to the conditions of the oral cavity and enamel solubility experiments.