Effect Of Triploidy Research Articles

Transcriptome sequencing and histology reveal dosage compensation in the liver of triploid pre-smolt Atlantic salmon

Triploid Atlantic salmon (Salmo salar L.) is seen as one of the best solutions to solve key issues in the salmon farming industry, such as the impact of escapees on wild stocks and pre-harvest sexual maturation. However, the effects of triploidy on salmon smoltification are poorly understood at the molecular level, even though smoltification is a very sensitive period that has a major influence on survival rate and performance of farmed salmon. In this study, we have compared the liver transcriptomes of diploid and triploid Atlantic salmon at three ontogeny stages: fry, parr and smolt. In diploid fish, a total of 2,655 genes were differentially expressed between fry and parr, whereas 506 genes had significantly different transcript levels between parr and smolts. In triploids, 1,507 and 974 genes were differentially expressed between fry and parr, and between parr and smolts, respectively. Most of these genes were down-regulated and 34 genes were differentially expressed between ploidies at the same stage. In both ploidy groups, the top differentially expressed genes with ontogeny stage belonged to common functional categories that can be related to smoltification. Nucleotide and energy metabolism were significantly down-regulated in fry when compared to parr, while immune system processes were significantly down-regulated in parr when compared to smolts. The close resemblance of enriched biological processes and pathways between ploidy groups suggests that triploidy is regulated by genome dosage compensation in Atlantic salmon. Histological analysis revealed that areas of vacuolization (steatosis) were present only in fry and parr stages, in contrast to a compact cellular histology with glycogen granules after smoltification. There was no significant difference in vacuolization between ploidy groups at the fry stage but the liver of diploid parr had a 33.5% higher vacuolization area compared to their triploid counterparts. Taken together, our data provide novel insights into the changes that occur at the molecular and histological level in the liver of both diploid and triploid Atlantic salmon prior to and during smoltification.

The effect of triploidy on the performance, gut microbiome and behaviour of juvenile Atlantic salmon (Salmo salar) raised at low temperature

Triploid Atlantic salmon (Salmo salar) aquaculture has been extensively considered for many years, but its development has so far remained very limited. This is mostly due to poorer farming performances of triploid fish (3 N) in comparison with their diploid (2 N) counterparts, with temperature seen as a key explanatory factor. Furthermore, there are many inconsistencies between studies and considerable knowledge gaps exist in triploid physiology and performance, especially at early life stages. The present work is a pilot experiment in which the temperature was kept constantly low (8 °C) during 149 days from 81 to 229 days post hatching (dph). We used a multi-trait approach with an emphasis on behaviour to investigate the performance of 3 N and 2 N Atlantic salmon. Specifically, we compared growth, survival, prevalence of malformation, gut microbiome, and behavioural traits such as swimming activity in response to a stressor, and boldness. Reared at a cold and constant temperature, juvenile triploid and diploid fish showed similar growth from 81 to 165 dph but a difference occurred at 221 dph. Interestingly, triploids outperformed diploids in terms of survival. The prevalence of deformity was low in both diploid and triploid fish and no lower jaw skeletal abnormalities were observed in live fish at the end of the experiment. Triploid and diploid fish displayed very similar swimming activity and boldness traits as well as a very similar gut microbiome. This multi-trait approach reveals that when raised at low temperature, triploid and diploid fish performed equally well, with even a better survival for triploids towards the end of the experiment. Our study emphasizes the need for developing different rearing protocols for diploid and triploid Atlantic salmon. Applying a lower temperature at early developmental stages in ectotherms inevitably slows their developmental rate and may allow fine tuning of key developmental structures, decreasing deformities at early and later life stages of triploids. Further research comparing different temperature profiles is needed to find the best compromise between growth performance and low malformation rate and to examine the long-term effect of low temperatures applied at an early stage of development. This is a crucial step to improve both triploid salmon performance and welfare.

Metabolic differentiation of diploid and triploid European sea bass juveniles

The effects of triploidy were studied on indices of growth and metabolism in juvenile European sea bass. Ploidy affected flesh quality of Dicentrachus labrax, as protein and water contents were significantly higher in triploid than in diploid fish and triploid fish exhibited significantly lower lipid content. Compared to 2n fish, triploid fish exhibited 53.4% and 28.6% more DNA and RNA, respectively, 17.2% higher RNA/DNA ratio and 28.7% more protein/DNA ratio. The activities of the aerobic metabolism enzyme CCO and the glycolytic LDH of the muscle tissue were significantly higher in the triploid fish. Nevertheless, the ratio of these two enzymes was lower in the triploids, indicating metabolic difference in the potential for aerobic metabolism. The increased activity of LDH may reflect a potential shift towards anaerobic metabolism required under demanding conditions, for example, during burst swimming, confirming the effects of ploidy on the aerobic swimming capacity of fish. The increased CCO activity of triploids observed in the present work indicates an effect of ploidy on the capacity for aerobic metabolism of triploid fish.

Effect of triploidy on liver gene expression in coho salmon (Oncorhynchus kisutch) under different metabolic states

BackgroundTriploid coho salmon are excellent models for studying gene dosage and the effects of increased cell volume on gene expression. Triploids have an additional haploid genome in each cell and have fewer but larger cells than diploid coho salmon to accommodate the increased genome size. Studying gene expression in triploid coho salmon provides insight into how gene expression may have been affected after the salmonid-specific genome duplication which occurred some 90 MYA. Triploid coho salmon are sterile and consequently can live longer and grow larger than diploid congeners in many semelparous species (spawning only once) because they never reach maturity and post-spawning mortality is averted. Triploid fishes are also of interest to the commercial sector (larger fish are more valuable) and to fisheries management since sterile fish can potentially minimize negative impacts of escaped fish in the wild.ResultsThe vast majority of genes in liver tissue had similar expression levels between diploid and triploid coho salmon, indicating that the same amount of mRNA transcripts were being produced per gene copy (positive gene dosage effects) within a larger volume cell. Several genes related to nutrition and compensatory growth were differentially expressed between diploid and triploid salmon, indicating that some loci are sensitive to cell size and/or DNA content per cell. To examine how robust expression between ploidies is under different conditions, a genetic/metabolic modifier in the form of different doses of a growth hormone transgene was used to assess gene expression under conditions that the genome has not naturally experienced or adapted to. While many (up to 1400) genes were differentially expressed between non-transgenic and transgenic fish, relatively few genes were differentially expressed between diploids and triploids with similar doses of the transgene. These observations indicate that the small effect of ploidy on gene expression is robust to large changes in physiological state.ConclusionsThese findings are of interest from a gene regulatory perspective, but also valuable for understanding phenotypic effects in triploids, transgenics, and triploid transgenics that could affect their utility in culture conditions and their fitness and potential consequences of release into nature.

Effect of triploidy on digestive enzyme activity of early stages of turbot (Scophthalmus maximus).

In the present work, growth and digestive enzyme activities of total acid and alkaline proteases, pepsin, trypsin, lipase, and α-amylase, as well as partial characterization of enzyme activity, were studied in diploid and triploid turbot. Growth was similar between both groups. Acid protease activity increased consistently during the experiment, for both diploid (2n) and triploid (3n) fish. The alkaline protease activity was always higher for triploids throughout the experiment. Proteolytic acid activity (pH2) was generally higher for diploids, at all temperatures tested. Higher activity was at pH2 and 3 for 2n and 3n fish, respectively. Regarding temperature, acid and alkaline protease activity was higher at 37°C and 60°C, respectively, for both groups. The general increase in pancreatic enzymes (trypsin and amylase) before 35days after hatching (DAH) and posterior decrease until 60 DAH. There was a marked effect on enzyme activity when changing from live prey to pellets (35 DAH), especially on triploids.

Changes in water temperature and oxygen: the effect of triploidy on performance and metabolism in large farmed Atlantic salmon

Changes in water temperature and oxygen: the effect of triploidy on performance and metabolism in large farmed Atlantic salmon

Water temperature and oxygen: The effect of triploidy on performance and metabolism in farmed Atlantic salmon (Salmo salar L.) post-smolts

The use of sterile triploids in Atlantic salmon aquaculture would mitigate the environmental risks associated with introgressive hybridization between escaped farmed and wild Atlantic salmon. However, production of farmed triploid salmon is limited due to reports of poorer growth and higher mortality when compared to diploids, in particular under sub-optimal environmental conditions. To address these concerns, we monitored triploid and diploid Atlantic salmon post-smolts at temperatures between 3 and 18°C and 100% oxygen saturation (O2 sat), and additional periods of 60% O2 sat (hypoxia) at 6 or 18°C, respectively. Feed intake and oxygen consumption rate were monitored throughout the experimental period. Muscle and blood samples were collected at 100 and 60% O2 sat at 6 and 18°C for analysis of white muscle energy phosphates (creatine phosphate, adenosine triphosphate) and carbohydrate fuels (glucose, glycogen) as well as blood clinical chemistry (whole blood: hematocrit; plasma: Na+, K+, Cl−, glucose, lactate, pH, triacylglycerol). Mortality was similar between ploidies, but higher in triploids compared to diploids during reduced O2 sat at 18°C. Compared to diploids, triploids had higher feed intake (% biomass) at ≤9°C, but lower feed intake at ≥15°C. Feed intake peaked at 12 and 15°C for triploids and diploids, respectively. Triploids progressively reduced feed intake with increasing temperature after peak feeding, indicating reduced scope for specific dynamic action with increasing water temperature. During hypoxia, triploids had lower feed intake than diploids at 6 and 18°C. The difference in feed intake was not associated with any ploidy effect on body weight gain or feed conversion ratio, but triploids had greater body length growth compared to diploids. At ≥15°C triploids consumed less oxygen than diploids. In the white musculature, the only observed difference between ploidies was a lower level of glycogen in triploids compared to diploids at 18°C and 100% O2 sat. In the blood plasma, the concentration of ions was lower and glucose level higher in triploids compared to diploids at 18°C and 60% O2 sat. The results of this study indicate that triploid Atlantic salmon post-smolts can substitute diploids, but are less tolerant to high seawater temperature and low O2 sat. For sea-cage farming of triploid salmon post-smolts, this would favour production areas with maximum temperatures of 15°C and sufficient oxygen. Statement of RelevanceThis study demonstrates that triploid Atlantic salmon post-smolts have lower temperature optima for feeding and growth than diploids, a similar physiological response to high temperatures, but higher mortality under suboptimal conditions. Consequently triploid Atlantic salmon post-smolts may be well suited for commercial farming in geographical regions with moderate water temperatures in the summer and autumn months.

Effect of triploidy in the expression of immune-related genes in coho salmonOncorhynchus kisutch(Walbaum) infected withPiscirickettsia salmonis

Effect of triploidy in the expression of immune-related genes in coho salmon<i>Oncorhynchus kisutch</i>(Walbaum) infected with<i>Piscirickettsia salmonis</i>

The effect of triploidy on vaccine side-effects in Atlantic salmon

Abstract Vaccination against bacterial diseases is an important aspect of commercial salmon production, but is known to have a number of unwanted side-effects including reduced growth, abdominal adhesions, and vertebral deformities. Our study objective was to compare these side-effects between diploid and sterile triploid salmon, the use of which would prevent genetic interactions between escaped farmed and wild salmon. A full factorial cross of vaccinated and unvaccinated, diploid and triploid, yearling (1 +) and under-yearling (0 +) mixed sex salmon were reared in triplicate in freshwater before common rearing in sea cages for 12–15 months. To further examine how ploidy may influence welfare with respect to vertebral deformities, a set of wild caught salmon were examined. Unvaccinated fish were larger (9% at termination) than vaccinated fish, but there was no effect of vaccination on skeletal deformities. In general, triploids grew as well or better in freshwater, but poorer in seawater compared to diploids, resulting in diploids being 12% larger than triploids at termination irrespective of smolt regime. In addition, triploids had a higher prevalence of fish with a least one deformed vertebra in 1 + smolts compared to diploids (34 vs 8%, respectively). However, vertebral compressions and fusions were observed in both ploidy, but were not apparent in the wild caught adult salmon control fish. Ploidy effects on the response to vaccination were limited to triploids having significantly higher vaccine-induced abdominal adhesion scores in 0 + smolts compared to diploids. Triploidy also prevented males becoming larger than females in vaccinated 0 + smolts in contrast to all other ploidy, vaccination, smolt regime combinations where males became the largest (8–12% at termination). Finally, notable levels of sexual maturation occurred in the male 0 + smolts, but fewer triploids matured as post-smolts or grilse in comparison to diploids. Based on our results, for best welfare practices the timing of vaccination may need to be altered when producing 0 + triploid smolts.

The effect of triploidy on the efficacy and physiological response to anesthesia with MS 222 and isoeugenol in Atlantic salmon post-smolts

Sterile triploid fish are increasingly being used in salmon aquaculture and fisheries. For production, welfare, and experimental reasons, it is important to understand the efficacy of anesthetics and the physiological response to anesthesia in triploid fish. The efficacy (time to anesthesia and recovery) of 30, 40, 50, and 80 mg Finquel® (MS 222) L−1 and 12.5, 20, and 30 mg (active ingredient) Aqui-S® (isoeugenol) L−1 and the acute hematocrit and plasma (cortisol, glucose, osmolality, lactate) response to 30, 50, and 80 mg Finquel® L−1 and 12.5 mg Aqui-S® L−1 was therefore measured in diploid and triploid post-smolt Atlantic salmon, Salmo salar. Ploidy had no effect on the efficacy of Finquel® or Aqui-S®. Although triploidy had significant transient effects on all physiological parameters measured following anesthesia, the differences were small and likely biologically negligible with respect to the ability of Atlantic salmon to recover from the range of anesthetics tested.

The effect of triploidy on the culture performance, deformity prevalence, and heart morphology in Atlantic salmon

The study objective was to compare the effect of ploidy on growth, downgrading, discards, and fish quality at slaughter, the prevalence of skeletal deformities (external examination: spinal, jaw and operculum; radiology: spinal), and heart morphology from a large production of diploid and triploid Atlantic salmon (Salmo salar) reared in triplicate (n=20000ploidy−1). Triploids were 15% heavier and 7% longer than diploids at seawater transfer but diploids were 10% heavier and 1% longer than triploids at slaughter. Triploidy had no effect on gutted mass for each quality classification but significantly reduced the percentage of fish classified as superior whilst increasing the amount of production and discard quality (mean %±SE (n=3ploidy−1): superior, 89.6±1.8 vs 83.7±1.4; production, 2.4±0.5 vs 6.5±0.1; discards, 0.9±0.2 vs 2.1±0.2 for diploids and triploids, respectively). As a result, less money was received per triploid fish compared to diploids (the average price fish−1 cage−1 (n=3 ploidy−1) ranged between 62.3–81.1 and 63.5–67.4 Norwegian kroner for diploids and triploids, respectively). Total discards and downgrading were increased by triploidy due to deformities and triploids also had more fish discarded due to “small fish” compared to diploids. Radiography demonstrated triploids had more fish with one or more deformed vertebrae (mean %, 22.0 vs 42.7 and 24.4 vs 48.9 in diploid and triploid, parr and post-smolts, respectively). Diploid seawater mortality was significantly lower than triploids (1.2–1.5 and 1.8–2.2% cage-1, respectively). Triploid food conversion ratios (FCR) and specific growth rates (SGR) were inferior to diploids during the latter half of seawater phase (range: FCR, 1.36–1.47 and 1.55–1.67; SGR, 0.49–0.53 and 0.44–0.46 for diploids and triploids, respectively). Triploids had a lower angle of the bulbus arteriosus at slaughter (mean angle±SE (n=3 ploidy−1): 46.5±0.1 and 39.1±1.3 in diploids and triploids, respectively). There was no effect of triploidy on ventricle mass, ventricle roundness, or the compact:spongy myocardium ratio. Sex had a significant effect on body length and ventricle mass with males 3% longer and having hearts 5.8% heavier than females. Overall the present data would suggest triploids are suitable for culture purposes but at a higher economic cost to the producer. In addition, future work should focus on reducing the prevalence of deformities in order to improve triploid quality and welfare.

Effects of triploidy on growth and protein degradation in skeletal muscle during recovery from feed deprivation in juvenile rainbow trout (Oncorhynchus mykiss)

Identifying physiological differences between diploid and triploid rainbow trout will help define how ploidy affects mechanisms that impact growth and nutrient utilization. Juvenile diploid and triploid female rainbow trout (Oncorhynchus mykiss) were either continually fed or fasted for one week, followed by four weeks of refeeding, and indices of growth and proteolysis-related gene expression in skeletal muscle were measured. Fasting reduced growth, and based on gene expression analysis, increased capacity for protein degradation. Regardless of feeding treatment, triploids displayed slightly greater feed intake and specific growth rates than diploids. Continually fed triploids displayed lower expression of several autophagy-related genes than diploids, suggesting that reduced rates of protein degradation contributed to their faster growth. Reduced expression of ubiquitin ligases fbxo32 and fbxo25 and autophagy-related genes during refeeding implicates reduced proteolysis in recovery growth. At one week of refeeding triploids exhibited greater gains in eviscerated body weight and length, whereas diploids exhibited greater gains in gastrointestinal tract weights. During refeeding two autophagy-related genes, atg4b and lc3b, decreased within one week to continually fed levels in the triploids, but in diploids overshot in expression at one and two weeks of refeeding then rebounding above continually fed levels by week four, suggesting a delayed return to basal levels of proteolysis.

Growth Performance of Triploid Red Tilapia Reared Under Laboratory Conditions

Triploidy could reduce breeding activity in tilapia without the use of hormones. In this study, the effect of triploidy on survival, growth, and gender of a line of red hybrid tilapia (Oreochromis mossambicus X Oreochromis niloticus) was assessed relative to the performance of diploid siblings. Triploidy was induced by preventing second polar body extrusion by applying either heat or cold shock. Growth was similar for both ploidies during the first 90 days of culture. However, at the age of 120 days, the average body weight of triploids produced by heat shock (215.5 ± 3.61 g) was significantly higher than that of cold shock (192.7 ± 2.6 g) and the diploid control (191.9 ± 1.74 g). Survival among triploids was inferior to diploids. Percentage of males in the triploid population was 82.9% in the heat-shocked treatment group, 54.8% in the cold-shock treatment, and 50% in the diploid control. Maximum attainable weight of red tilapia was calculated by applying the Ford-Walford growth plot: 650 g (heat-shocked triploids), 490 g (cold-shocked triploids), and 440 g in the diploid control.

The effect of triploidy and vaccination on neutrophils and B-cells in the peripheral blood and head kidney of 0+ and 1+ Atlantic salmon (Salmo salar L.) post-smolts

Sterile triploid fish are being used in aquaculture to prevent early unwanted sexual maturation and the genetic interaction between wild and cultured fish; however, triploid fish are typically considered to be more susceptible to disease than diploid counterparts. Proportions of leucocytes from the head kidney and peripheral blood were identified using monoclonal antibodies and flow cytometry in triploid and diploid, vaccinated and unvaccinated, out-of-season (0+) and 1+ Atlantic salmon (Salmo salar L.) three weeks post seawater transfer. Triploid 1+ fish were significantly (P<0.05) heavier than diploid fish at the time of sampling, whereas triploid 0+ had a significantly lower condition factor than diploids. Ploidy had a significant effect on the proportion of B-cells in the blood of both 0+ and 1+ fish, and the head kidney of 1+ fish, with triploids having lower proportions of B-cells to diploids in both smolt groups. In addition, a significant ploidy×vaccination interaction effect was observed in the response of neutrophils in the blood (vaccinated diploids had a higher mean proportion than diploid unvaccinated) and B-cells in the head kidney (in vaccinated fish, triploids had a lower mean proportion than diploids) in 0+ smolts. Vaccination was found to significantly increase the proportion of B-cells in the head kidney of 1+ smolts in both ploidy. Size (fish weight) was positively correlated with neutrophil proportions in 1+ fish. Our findings are discussed in relation to the physiological differences related to ploidy. The results suggest that ploidy as well as smelting regime influences the immune system of Atlantic salmon post-smolts.

Effect of triploidy on growth and ionoregulatory performance in ocean-type Chinook salmon: A quantitative genetics approach

The use of triploid salmon for aquaculture is attractive as they do not mature sexually, limiting losses associated with poor flesh quality in mature fish and posing less genetic risk to wild stocks if they escape. Inconsistent survival and growth performance in triploid fish, however, has limited their implementation. In our study, ocean-type Chinook salmon (Oncorhynchus tshawytscha) were bred using replicated 3×3 factorial mating designs to create 18 families to test whether triploidization resulted in changes in growth and ionoregulation performance in freshwater and seawater. Eggs were pressure shocked after fertilization to create triploid offspring in a subset of each family. In spring, freshwater fish were sampled for size and gill Na+, K+-ATPase activity. Plasma chloride and cortisol were measured following a 24-h saltwater challenge. Growth performance was monitored for a further four months following transfer to sea water. We found significant effects of ploidy and sire (paternal effect) on smolt weight, as well as on gill Na+, K+-ATPase activity, although the latter did not correspond with performance in a 24-h saltwater challenge. Following four months of ocean growth, diploid animals were consistently larger, with greater circulating levels of insulin-like growth factor-1 than triploid sibs, although specific growth rates did not differ. Conversely, gill Na+, K+-ATPase activity at that time was significantly higher in triploid than diploid fish. When the phenotypic variance for the various traits was partitioned, triploids exhibited significantly greater additive genetic variance and maternal effects across all traits relative to diploid fish — indicating that gene dosage effects were primarily additive. The strong family effect indicates that genotype has a substantial role in determining the effects of ploidy manipulation on ionoregulatory and growth performance in Chinook salmon.

Effects of triploidy after intracytoplasmic sperm injection on in vitro fertilization cycle outcome

To evaluate the impact on the rates of clinical pregnancy and live birth of polyploidy after intracytoplasmic sperm injection (ICSI). Retrospective cohort study. University-based IVF center. One hundred forty-three patients undergoing their first IVF-embryo transfer cycle requiring ICSI. None. Patients were divided into two groups on the basis of the proportion of post-ICSI triploid fertilization that was observed at the time of fertilization assessment: group 1 included patients with <or=20% three-pronuclear (3PN) zygotes, and group 2 included patients with >20% 3PN zygotes. The primary outcomes compared between groups were pregnancy and implantation rates; secondary outcome measures included clinical-pregnancy rate and live-birth rate per embryo transfer. Pregnancy, implantation, clinical-pregnancy, and live-birth rates were significantly higher in the cohort of patients who had <or=20% of embryos appearing triploid, compared with the group who had >20% of zygotes appearing triploid (relative risk [RR] for pregnancy, 2.4 [95% confidence interval {CI}, 1.22-4.77]; RR for implantation, 2.6 [95% CI, 1.17-5.56]; RR for clinical pregnancy, 2.8 [95% CI, 1.16-6.85]; and RR for live birth, 2.6 [95% CI, 1.06-6.38]). The proportion of 3PN zygotes after ICSI had a statistically significant inverse relationship to clinical-pregnancy rate. The proportion of triploid zygotes after ICSI serves as a negative prognostic indicator for IVF cycle outcome. This finding suggests that triploidy proportion is a surrogate marker of oocyte competence that represents the integrity of the oocytes in the entire recruited cohort. Such findings therefore may influence recommendations for embryo transfer number and freezing of supernumerary embryos.

Effect of triploidy on quality traits of shi drum (Umbrina cirrosa L.) until the second rearing year

Carcass and flesh morphometric, reological and chemical traits of triploid (3n) and diploid (2n) shi drum (Umbrina cirrosa L.) were evaluated through 7 months. Three age groups, 17-, 21- and 24-month-old fish, were investigated. The effects of ploidy were statistically evaluated and the weight of fish was included in the model as a covariate because triploids grew less than diploids. As expected, fish weight was found to be significantly correlated with all the investigated morphometric traits, but showed a negative correlation with some chemical (pH) and colour traits (lightness) of raw fillet. In comparison with controls, triploid shi drums were characterized by different morphological traits that involved a slender body shape. In triploids, a reduction in condition factor, backbone weight, dressing index and an increase in the agility index were also recorded. When the commercial size (i.e. over 300 g) was achieved, triploids exhibited larger coelomatic and fillet (dorsal white muscle) fat deposition than diploids. Among reological traits, colour and texture were affected by ploidy; raw fillet lightness and cooked flesh tenderness were higher among triploids in all the investigated age groups. As fish were fed with a restricted feeding regimen, fillet fat deposition was supposed to be limited. Thus, the effects of ploidy on reological traits may be only partially explained by lipid fillet amount and are supposed to be more related to different fibre muscle architecture.

The activity of several components of the innate immune system in diploid and triploid turbot

The use of triploid fish may be of interest in research, e.g. study of how this condition affects the size and activity of cells. In addition, triploid fish are sterile and production of triploids in fish species that are marketed after reaching sexual maturity may be of economic interest. In the present study, the effects of triploidy on the activity of several components of the innate immune system of turbot ( Psetta maxima L) were determined. Triploid turbot had bigger cells (erythrocytes and neutrophils) but the number of blood erythrocytes, leucocytes and thrombocytes was lower than in diploid fish. The differential cell count was similar in both types of fish. The respiratory burst and the phagocytic activities were higher in neutrophils of triploid turbot. However, because the number of neutrophils was higher in diploids, the total respiratory burst activity and the phagocytosis per microliter of blood was similar in both types of fish. No differences were found in serum complement, lysozyme or bactericidal activities. The results indicate that the activities of the humoral components of the innate immune system tested are similar in diploid and triploid fish and that the lower leucocyte number found in triploids is compensated for by higher cell activity.

Effects of triploidy on feed efficiency, morphometric indexes and chemical composition of shi drum, Umbrina cirrosa L.

Effects of triploidy on feed efficiency, morphometric indexes and chemical composition of shi drum, Umbrina cirrosa L.

Effect of triploidy on paternal and maternal variance components in brown trout, Salmo trutta L.

The covariation between diploid and triploid progenies from common breeders and the effect of triploidy on the parental variances were investigated in brown trout (Salmo trutta L.) using two progeny testing experiments, sampling, sires and dams respectively, from the same population. The traits studied were body weight, growth, condition factor and red spotting of the skin. Triploidization generated some interactions with the parental breeding value, but their effect was minor (less than 20% of the genetic variance, in most cases) as compared with the amount of variation common to both ploidy levels. These interactions were mainly caused by a scale effect, triploidy reducing the variance attributable to sires and increasing the variance attributable to dams. Actual lack of correlation (genetic correlation significantly less than 1) between diploid and triploid familial performances was observed in a single instance out of 18. The modification of respective parental variance components by triploidy, already observed in the rainbow trout Oncorhynchus mykiss (Walbaum), appears as a logical consequence of the genetic make-up of triploids, and should be taken into account in selective breeding.