Stereoselective bioaccumulation,transformation, and toxicity of triadimefon in Scenedesmus obliquus

In this study the stereoselective bioaccumulation and transformation of triadimefon and the toxicity of triadimefon and its metabolite triadimenol to the green algae Scenedesmus obliquus were studied. In growth inhibition experiments, triadimenol was more toxic than triadimefon, and (1S,2R)‐triadimenol, which has the largest fungicidal activity, presented the highest toxicity to the algae. In bioaccumulation experiments, triadimefon was rapidly taken up by algae cells, and the decrease in the concentration of triadimefon was accompanied by an increase in triadimenol. The transformation of S‐(+)‐ triadimefon was faster than that of the R‐(−)‐enantiomer, resulting in four triadimenol stereoisomers at different forming rates: B2 (1S, 2S) > B1 (1R, 2R) > A2 (1S, 2R) > A1 (1R, 2S). Thus, it is necessary to explore the enantioselective toxicology and ecological fate of these chiral pesticides in an environmental risk assessment. Also, their metabolites should be paid specific attention to since they may pose higher ecological risks.     

Effects of aluminium and cortisol on in vitro calcium deposition on otoliths in rainbow trout

Aluminium (1–100 μM) reduced in vitro calcium deposition on otoliths concentration-dependently in rainbow trout, but cortisol (1 and 10 μg ml⁻¹) had no effect.     

The bold and the shy: individual differences in rainbow trout

Boldness and shyness were investigated as 'personality' traits in hatchery-reared rainbow trout Oncorhynchus mykiss . Bold fish spent more time in an open area and were more active than shy fish and these behaviours could be used as indicators of boldness and shyness. These differences were related to learning ability in a simple conditioning task. Bold fish learned the task more quickly than shy fish.     

Absence of developmental incompatibility in hybrids between rainbow trout and two subspecies of cutthroat trout

We examined the developmental rate of hybrids between rainbow trout (Salmo gairdneri) and two subspecies of cutthroat trout: westslope cutthroat trout (Salmo clarki lewisi) and Yellowstone cutthroat trout (Salmo clarki bouvieri). These taxa show considerable genetic divergence at 42 structural loci encoding enzymes; the mean Nei's d between the rainbow trout and the two species of cutthroat trout is 0.22. We used four measures of developmental rate: time of hatching and yolk resorption, rate of increase in activity of four enzymes, and time of initial detection of seven isozyme loci. The two cutthroat trout subspecies reached hatching and yolk resorption earlier than rainbow trout. Cutthroat trout had higher relative enzyme activities than rainbow trout from deposition of eye pigment to hatching. There was no difference in the rate of increase in enzyme activity or time of initial expression of these loci between these species. Hybrids showed developmental rates intermediate or similar to that of the parental species using all measures. Our results indicate an absence of regulatory and developmental incompatibility between these taxa.This research was supported by NSF Grants ISP-8011449 and BSR-8300039. M.M.F. was supported by a postgraduate scholarship from the Natural Sciences and Engineering Research Council of Canada.     

Histology and carbohydrate histochemistry of the alimentary canal in the rainbow trout Oncorhynchus mykiss

A histological and histochemical analyses were carried out on the entire alimentary canal of the rainbow trout Oncorhynchus mykiss . In particular the oesophageal region showed presence of terminal β‐D‐galactose(1–3)‐N‐acetylgalactosamine and α‐N‐acetylgalactosamine. In the anterior and posterior regions of the stomach, lining epithelium and gastric pits exhibited the presence of β‐gal and α‐GalNAc. In addition sialoglycoconjugates having sialic acid–β–galactose(1–3)‐N‐acetylgalactosamine and sialic acid‐N‐acetylgalactosamine as terminal tri‐ and di‐saccharides, were demonstrated. In proximal and distal intestine goblet cells showed the presence of sialoglyconjugates, having sialic acid‐β‐gal(1–3)‐GalNAc and sialic acid‐GalNAc as terminal sequences, belonging to N‐linked chains. In the enterocytes of the entire intestine, terminal GlcNAc, α‐Gal, α‐fucose were found.     

Effect of genetic origin of the fish on in vitro proliferation of muscle myosatellite cells of rainbow trout

In two rainbow trout Oncorhynchus mykiss strains fed 5% of body mass for 1 week, no significant differences were observed between the two strains in the in vitro proliferation rate of myosatellite cells isolated from white axial muscle and studied for 8 days following the incorporation of 5-bromo-2'-deoxyuridine. Nonetheless, the differentiation process and formation of myotubes started first in the strain displaying the fastest growth and the myotubes attained a more developed stage in these fish: more numerous and bigger myotubes. When the two strains were submitted to starvation for 1 week, the fast growing strain showed a faster response to the culture medium and a significantly higher proliferation rate than the slow growing one.     

Biochemical polymorphisms in muscle and liver extracts and in the serum of the rainbow trout Salmo gairdneri

The frequency of polymorphic phenotypes determined by starch gel electrophoresis from six enzyme systems was investigated on 664 rainbow trout (stock I) originating equally from six full-sib families. The enzyme systems studied were CA, AKP, G-6-PD, SOD, AEP, and 6-PGD.
On material deriving from six parental matings totalling 212 offspring (stock II) the mode of inheritance of the first four enzymes (AEP and 6-PGD were not polymorphic) and the additional systems IDH, PGM, Alb, and Psta, not analysed in stock I, were investigated.
The G-6-PD system showed no polymorphism in the family material. The CA, PGM, Alb, and Psta systems were easily identifiable. Their mode of inheritance with two alleles each can be considered as proven. For SOD three alleles, in four out of six possible progeny types, were found, for which the postulated mode of inheritance was confirmed.
For IDH the mode of inheritance found by Allendorff & Utter (1973) was confirmed. This pattern shows two disomic gene loci, one of which is monomorphic, while the other carries four different alleles.
The number of alleles and their mode of inheritance for the AEP system, which was not clearly identifiable, could not be elucidated.     

Evaluation of in vitro endocytosis and antibody synthesis by rainbow trout head kidney cells treated with bovine lactoferrin

Bovine lactoferrin (LF) was evaluated for its capacity to modulate the in vitro endocytosis (phagocytosis and pinocytosis) and antibody synthesis by head kidney cells of rainbow trout Oncorhynchus mykiss . Phagocytic activity and phagocytic index of head kidney macrophages, determined by measurement of ingested yeast, were influenced by bovine LF starting from the LF concentration of 1 and 0·1 μg ml⁻¹, respectively. Endocytosis, determined by the evaluation of droplet uptake of neutral red dye solution, was significantly enhanced by 10 μg ml⁻¹ of LF. In contrast, antibody synthesis by head kidney cells, evaluated by immunoenzymatic assay, from fish immunized against human‐γ‐globulins (HGG) in vivo was not affected by bovine LF. Although these results showed that bovine LF had no effect on specific immunoglobulin production in vitro , an enhancement of the acquired immune response may be assumed in LF‐treated fish in vivo , as observed in higher vertebrates.     

Influence of temperature on silver accumulation and depuration in rainbow trout

To assess the influence of water temperature on silver uptake, rainbow trout Oncorhynchus mykiss ( c . 50 g; held at 13° C) were exposed to 0·1 μM AgNO₃ in ion‐poor water for 1 week at 4 and 16° C without previous temperature acclimation. To assess the influence of temperature on elimination of previously accumulated Ag, rainbow trout were exposed to 0·1 μM AgNO₃ in ion‐poor water for 1 week at 12° C, then were randomly divided amongst two Ag‐free water containers, differing only in temperature (3 and 16° C), for 2 months. In the uptake study greater accumulation of Ag was seen in the gills, plasma and especially the livers and bile of 'warm' rainbow trout (16° C) compared to 'cold' rainbow trout (4° C), which can be explained by the higher metabolic rates of the warmer fish. In the depuration study there was no net elimination of Ag from the livers and bile but there was biphasic elimination of Ag from the gills and plasma of 'warm' and 'cold' fish, but with few differences between them. This indicated that temperature‐dependent processes were less important in Ag elimination than in Ag uptake. Toxicokinetic modelling of Ag uptake by livers indicated four‐fold greater uptake of Ag by 'warm' rainbow trout compared to 'cold' rainbow trout (one compartment uptake model). Elimination of previously accumulated Ag from the plasma was best fitted by a two compartment rate‐constant based model, with approximately half the plasma Ag load eliminated within 24 h, followed by slower elimination of Ag over 2 months.     

Isolation and culture of somatotrophs from the pituitary of the rainbow trout: Immunological and physiological characterization

Summary The aim of the present paper was to obtain somatotroph- and gonadotroph-enriched populations from collagenase dispersed pituitaries of male rainbow trout. Inasmuch as the percentage of immunoreactive gonadotrophs and somatotrophs present in pituitaries was higher at spermiation than at the beginning of spermatogenesis, we tried such a cell separation with fish at this stage of spermatogenesis. Cells were fractionated using their differences in buoyant density with centrifugation in Percoll solutions. The use of Percoll linear gradients (1.110 to 1.027 g/ml) showed that somatotroph cells have a density of between 1.102 and 1.064 g/ml whereas gonadotrophs are spread over the range of the gradient. It was thus possible, by using linear or discontinuous Percoll gradients, to obtain 95 to 67% (mean 80%) enriched somatotropic cell fractions while no enriched gonadotropic cell fractions were collected. The fractionated cells kept their ability to be cultured and to be responsive to specific secretagogues. Somatostatine induced a 80 to 85% decrease in growth hormone release per somatotroph in the initial cell suspension as well as in the different cell fractions. On the other hand, the basal growth hormone release per cell was lower in the fractions containing cells with a density lower than 1.062 g/ml. Inversely, the gonadotrophs have a basal release per cell independent of their density, and this is also available for their responsiveness to salmon gonadotropin-releasing hormone.     

Circadian rhythms of demand-feeding and locomotor activity in rainbow trout

Under free-running conditions, most rainbow trout displayed circadian feeding rhythms, although the expression of circadian rhythmicity depended on the experimental condition: 16·7% of fish under constant dim light (LL dim), 66·1% under a 45 :45 min light-dark cycle (LD pulses), and 83·8% under constant light (LL). Under LD pulses, the period length of the free-running rhythms for feeding was significantly shorter (21·9 ± 0·7 h, n =8) than under LL (26·2 ± 0·3 h, n =10). Period length for locomotor activity under LL was 25·8 ± 0·6 h ( n =4). Under LD conditions, the daily demand-feeding profile was always confined to the light phase and chiefly composed of two main episodes, directly after lights on (light elicited) and in anticipation to lights off (endogenous). Contrasting to feeding, the diel locomotor activity profile varied remarkably: a diurnal activity pattern at the bottom, while a clearly nocturnal pattern at the surface. These results contribute to a better understanding of feeding and locomotor rhythms of rainbow trout, providing evidence for the existence of a biological clock involved in their circadian control. This finding contrasts with the previously recorded lack of an endogenous oscillator in the pineal organ driving the rhythmic secretion of melatonin, which suggests different locations from the pineal for the circadian pacemakers in this species.     

Contrasting seasonal modulation of the stress response in male and female rainbow trout

Between June and September the magnitude of the plasma cortisol response of maturing male and female rainbow trout to confinement was indistinguishable. A progressive increase in confinement-induced cortisol levels in both sexes occurred during May to September, associated with the seasonal rise in water temperature. Between September and January a reduction of >50% in the magnitude of the cortisol response to confinement in male fish (but no decline in females) coincided with declining water temperature and significant increases in plasma 11-ketotestosterone and elevated plasma testosterone levels. Plasma oestradiol-17β levels were significantly greater in females than males throughout the study period and this difference was maximal between September and January. However, plasma testosterone was also elevated in females during this period and levels overall were higher than those in male fish. Previous studies have shown oestradiol-17β and testosterone to have diametrically opposed effects on stress responsiveness in trout, with the former enhancing, and the latter suppressing, the cortisol response to a stressor. The relative roles of androgens, estrogen and water temperature in modulating the stress responsiveness of rainbow trout are discussed.     

虹鳟肝组织新转录本分析及基因结构优化

目的虹鳟热应激下肝RNA-seq数据中新转录本的分析及已注释基因结构优化。方法以虹鳟肝为材料提取总RNA,构建cDNA文库,并利用Illumina双端测序Hiseq 2500平台进行测序。运用Cufflinks软件对测序数据进行组装,将其与虹鳟参考基因组进行序列比对。结果发掘新转录本6555个,其中30个新转录本在热应激前后差异表达(P<0.05)。与GO数据库比对对新转录本进行功能注释,获得3097个新转录本的注释。与KEGG数据库比对,共有3617个新转录本注释到284条代谢通路中。对19 424个已注释基因的结构进行优化,延伸了14 719个基因的5′端和14 796个基因的3′端。结论通过对发掘的6555个新转录本分析,并对19 424个已注释基因结构优化,为虹鳟基因组注释信息的完善提供了有力的借鉴,并为进一步了解虹鳟热应激的机制提供更有力的理论基础。     

Characterization of sugar moieties and oligosaccharide sequences in the distal intestinal epithelium of the rainbow trout by means of lectin histochemistry

Lectin histochemical study was performed on the distal intestinal mucosa of the rainbow trout. A panel of 25 biotinylated leetins for detection of sugar residues and oligosaccharide sequences of glycoconjugates on Bouin's solution-fixed paraffin embedded sections were used as probes. The avidin-biotin-peroxidase complex (ABC) was used to visualize the binding sites of lectins. A rich supply of carbohydrates was detected in this gut mucosal region. Marked differences in lectin labelling of goblet cells and enterocytes (absorptive cells) probably reflect various functional activities. The results are compared with those (scarce) obtained from other teleosts. Species differences in carbohydrate residue composition may be related to various feeding habits. The roles of posterior intestinal glycoconjugates in host-parasite interaction, macromolecular ingestion and immunological implications are discussed.     

Effects of food deprivation on 24 h-changes in brain and liver carbohydrate and ketone body metabolism of rainbow trout

Plasma glucose, lactate and acetoacetate, brain glycogen and acetoacetate, and liver acetoacetate, glycogen and lactate in fed rainbow trout exhibited daily changes. However, no daily changes were observed in the activities of the brain enzymes glycogen synthetase, 6-phosphofructo 1-kinase, and lactate dehydrogenase. Depending on the length of the previous fasting period most daily changes observed in the metabolic parameters of fed fish disappeared, except for liver acetoacetate levels, which displayed daily changes in both fed and fasted fish. These results suggest that feeding is an important factor regulating most daily changes in the brain and liver carbohydrate and ketone body metabolism of rainbow trout.     

Cortisol and immune characteristics in rainbow trout (Oncorhynchus mykiss) selected for high or low tolerance to stress

The influence of exposure to stressors on cortisol and the non-specific immune traits lysozyme and serum haemolytic activity were examined in second generation rainbow trout ( Oncorhynchus mykiss ) selected for either high or low serum cortisol level following a confinement stress. Lysozyme and serum haemolytic activity were also assessed, together with levels of specific antibodies against Aeromonas salmonicida A-layer, Vibrio salmonicida O-antigen and Vibrio anguillarum O-antigen, following injection of vaccines against these pathogens.
Significant differences in mean cortisol levels between the two selection lines were observed, but in only one of two stress experiments was the 'high-stress' line found to have the higher cortisol level; in the other experiment the 'high-stress' line had significantly lower cortisol levels than the 'low-stress' line. Lysozyme levels were in four of four assessments higher in the high-stress line than in the low-stress line, whereas components of serum haemolytic activity tended to be lower in the high-stress line than in the low-stress line. Levels of specific antibodies against all three bacterial pathogens were elevated following the injection of the vaccines. Only antibody production against A. salmonicida A-layer was significantly different between the two lines, the higher production of antibody being in the high-stress line.     

Temperature and oxygen tension influence the development of muscle cellularity in embryonic rainbow trout

Muscle cellularity at a developmental stage around the time of hatching was examined in rainbow trout which had been reared from the eyed stage at three different temperature regimes (5, 10 and 15° C) and different O₂ tensions [70% of air saturation value (ASV) at 5° C, 100% of ASV at all temperatures, and 150% of ASV at 10 and 15° C]. It was found that, as has been shown for other species, there was a difference in muscle fibre numbers and fibre cross-sectional areas between some of the regimes. There was a decrease in fibre number at the intermediate and higher temperature, and a decrease in fibre size at the high temperature. The temperature effects observed were modified by the applied changes in O₂ tension. An increased O₂ tension at 10° C led to an increase in fibre size whereas a decrease in O₂ tension at the low temperature resulted in a decrease in fibre number. The largest total white muscle cross-sectional area was achieved at 10° C under high O₂ conditions. Temperature and O₂ tension therefore had a clear effect on muscle cellularity and there was a significant interaction between the two parameters.     

Stress from air emersion fails to alter chloride cell numbers in the gills of rainbow trout

Air emersion stress caused an elevation in blood plasma cortisol of rainbow trout Oncorhynchus mykiss but this acute stressor did not elicit chloride cell proliferation in the gill tissue within 2 weeks following the disturbance.