Triploidy in the hematology of jundia juveniles (Siluriformes: Heptapteridae)

Zebrafish (Danio rerio) Gynogenetic Production by Heat Shock: Comparison Between Mitotic and Meiotic Treatment

Inbred species are useful resources for a variety of biomedical research applications. To create isogenic zebrafish, it is feasible to stop meiosis II (repeatedly) or mitosis (two times) in a haploid embryo by applying pressure or by delivering a heat shock, respectively. In this study, to improve the repeatability, we suggest a less complicated approach based on sperm ultraviolet-C (UV-C) exposure for a shorter period followed by heat shock at various temperatures, eliminating the use of pressure in meiotic therapy since heat shock is more accessible to laboratories. In this study, the survivability rates of meiotic (Mei) and mitotic (Mit) gynogenesis offspring produced by various combinations of irradiation (28.5, 105, and 210 mJ/cm2) and temperature (Mei: 40.40°C, 40.60°C, or 40.90°C; Mt: 41.40°C, 41.90°C, or 42.45°C) were compared with diploid (C) and haploid (H) controls. Our findings demonstrated that 40.60°C and 41.90°C were the most suitable temperatures to produce meiotic and mitotic gynogenesis, respectively, whereas 28.5 mJ/cm2 was more successful in ensuring haploid embryos. As a result, we deduced that meiotic gynogenesis produces more viable offspring than the mitotic approach and requires a lower temperature to maintain the second polar body.

Can Vitamin C Supplementation Improve the Antioxidant Capacity of Rhamdia quelen Fish Exposed to Atrazine?

Atrazine (ATZ) is one of the pesticides mostly widely used in Brazil; several studies have shown the toxic effects of this herbicide on aquatic organisms such as fish. Thus, it is absolutely necessary finding alternatives to protect the health of fish, mainly of species commercially important for aquaculture, which may be exposed to atrazine deriving from agricultural runoff. The aim of the current study was to investigate interactions between dietary supplementation with vitamin C (Vit C) antioxidant and exposure to ATZ in Rhamdia quelen fish exposed to this herbicide. R. quelen specimens were divided into four groups: (1) CTRL, (2) VitC, (3) ATZ, (4) ATZ + VitC. Groups 3 and 4 were exposed to ATZ (10 µg L^-1) for 96 h, after 30 days of VitC supplementation (1 g kg^-1). Liver samples were collected for biomarker assays. Group 4 was the only group presenting decreased protein carbonyl content. Non-protein thiol (NPSH) levels were significantly higher in groups VitC, ATZ and ATZ + VitC than in CTRL. Group ATZ + VitC presented significant increase in glutatione-peroxidase (GPx) activity in comparison to the other investigated groups. Ascorbic acid (AA) levels were significantly higher in group VitC and lower in group ATZ. Therefore, interactions between herbicide ATZ and dietary supplementation with Vit C have shown biochemical changes in R. quelen fish. Thus, dietary supplements with adequate amounts of Vit C can be added as antioxidants to the diet of fish bred in aquaculture systems in order to protect them from exposure to ATZ.

Effects of triploid induction on innate immunity and hematology in Astyanax altiparanae

Triploid induction is a promising biotechnique that could be used to enhance aquaculture yields in the near future. However, studies conducted with several fish species have demonstrated that the presence of an extra set of chromosomes may result in deleterious health effects. Furthermore, studies of fish immune responses still need to be conducted before these specimens can be readily commercialized. In the study presented herein, we evaluated the effects of triploid induction on hematology, erythrocyte morphometry and morphology, phagocytosis, and the expression levels of IL-1β and TGF-β using specimens of the Neotropical species, Astyanax altiparanae. In general, the cell counts of erythrocytes, leukocytes, and neutrophils in triploid fish were lower than those in diploid fish. The erythrocytes of triploid fish were larger than those found in diploid fish, but also demonstrated considerably higher frequencies of cellular and nuclear abnormalities. Although not statistically significant, triploid induction resulted in a phagocytic capacity (PC) 20% lower than that found with diploid fish. No notable differences were observed in phagocytic index (PI). Gene expression levels for the cytokine IL-1 were lower in tissues from the head kidney, liver, and spleen of triploid fish with respect to diploid fish. Gene expression levels of TGF-β were lower only in the spleen of triploids compared to diploids. In conclusion, triploid induction resulted in A. altiparanae specimens with immune impairments and potentially lower resistances to disease and low-quality environments.

Heat-induced triploids in Brycon amazonicus: a strategic fish species for aquaculture and conservation

Triploidization plays an important role in aquaculture and surrogate technologies. In this study, we induced triploidy in the matrinxã fish (Brycon amazonicus) using a heat-shock technique. Embryos at 2 min post fertilization (mpf) were heat shocked at 38°C, 40°C, or 42°C for 2 min. Untreated, intact embryos were used as a control. Survival rates during early development were monitored and ploidy status was confirmed using flow cytometry and nuclear diameter analysis of erythrocytes. The hatching rate reduced with heat-shock treatment, and heat-shock treatments at 42°C resulted in no hatching events. Optimal results were obtained at 40°C with 95% of larvae exhibiting triploidy. Therefore, we report that heat-shock treatments of embryos (2 mpf) at 40°C for 2 min is an effective way to induce triploid individuals in B. amazonicus.

Multidisciplinary haematology as prognostic device in environmental and xenobiotic stress-induced response in fish

The variations of haematological parameters hematocrit, hemoglobin concentration, leukocyte and erythrocyte count have been used as pollution and physiological indicators of organic dysfunction in both environmental and aquaculture studies. These parameters are commonly applied as prognostic and diagnostic tools in fish health status. However, there are both extrinsic and intrinsic factors to consider when performing a blood test, because a major limitation for field researchers is that the "rules" for animal or human haematology do not always apply to wildlife. The main objective of this review is to show how some environmental and xenobiotic factors are capable to modulating the haematic cells. Visualizing the strengths and limitations of a haematological analysis in the health assessment of wild and culture fish. Finally, we point out the importance of the use of mitochondrial activities as part of haematological evaluations associated to environment or aquaculture stress.

Pressure shock triploidization of Salmo trutta f. lacustris and Salvelinus umbla eggs and its impact on fish development

The study tested the efficiency of hydrostatic pressure triploidization methods for Salmo trutta f. lacustris and Salvelinus umbla and investigated the effects on survival rate, skeletal malformation, and on morphometrics and cellular composition of gills, spleen, liver, kidney, intestine, and blood. In Salmo trutta f. lacustris a 100% triploidy rate in combination with high larvae survival rate (80% in comparison to control) was obtained when treating eggs with a pressure of 66 × 10³ kPa 360 °C temperature minutes (CTM) post fertilization for 5 min, in Salvelinus umbla with a similar pressure after 270 CTM. Juvenile triploid Salmo trutta f. lacustris and Salvelinus umbla (145 days post hatch) had neither an increased rate of mortality, nor an increased rate of malformations. In triploid Salmo trutta f. lacustris and Salvelinus umbla the erythrocyte volume was 50% higher and the erythrocyte concentration in peripheral blood 25-35% lower relative to diploids. In triploids also the erythrocytes surface area: volume ratio was reduced. Gills of triploid Salmo trutta f. lacustris and Salvelinus umbla had increased width of primary lamellae and increased length of secondary lamellae which might compensate for unfavorable erythrocytes surface area: volume ratio. Length of the digestive tract and histology of kidney, liver, spleen, and gills were only investigated in Salmo trutta f. lacustris. In triploids the hematopoietic tissue of the kidney was decreased by 12%, the spleen index by 53%, and the erythroblast concentrations of the spleen by 42% relative to diploids, possibly indicating reduced erythropoiesis. Length of the digestive tract and cellular arrangement of intestine, liver, and gills were not affected. In summary, the used triploidization procedure seems a reliable method not counteracting the principles of animal welfare.

Protein and lipid metabolism adjustments in silver catfish (Rhamdia quelen) during different periods of fasting and refeeding

The fish may experience periods of food deprivation or starvation which produce metabolic changes. In this study, adult Rhamdia quelen males were subjected to fasting periods of 1, 7, 14, and 21 days and of refeeding 2, 4, 6, and 12 days. The results demonstrated that liver protein was depleted after 1 day of fasting, but recovered after 6 days of refeeding. After 14 days of fasting, mobilization in the lipids of the muscular tissue took place, and these reserves began to re-establish themselves after 4 days of refeeding. Plasmatic triglycerides increased after 1 day of fasting, and decreased following 2 days of refeeding. The glycerol in the plasma oscillated constantly during the different periods of fasting and refeeding. Changes in the metabolism of both protein and lipids during these periods can be considered as survival strategies used by R. quelen. The difference in the metabolic profile of the tissues, the influence of the period of fasting, and the type of reserves mobilized were all in evidence.

Hematological, morphological, biochemical and hydromineral responses in Rhamdia quelen sedated with propofol

Rhamdia quelen morphophysiological responses to propofol sedation were examined. The purpose was to investigate whether propofol would be a suitable drug to be used in fish transport procedures. Fish were exposed to 0, 0.4 or 0.8 mg L(-1) propofol for 1, 6 or 12 h in 40 L tanks, simulating open transport systems. Propofol was able to prevent the peak of cortisol levels experienced by the group exposed to 0 mg L(-1) propofol at 1 h. At 0.4 mg L(-1), propofol also preserved the stability of hematological (hematocrit, red blood cell count, hemoglobin, mean corpuscular volume, mean corpuscular hemoglobin and mean corpuscular hemoglobin concentration), morphological (red blood cell area), biochemical (cortisol, glucose, lactate, total protein, ammonia, urea, alkaline phosphatase, alanine aminotransferase and aspartate aminotransferase) and hydromineral (Na(+), Cl(-) and K(+) plasma levels) indicators of stress. Such results suggest that sedation with propofol at 0.4 mg L(-1) is suitable for R. quelen transport.