The aim of the present study was to compare the efficiency of vitrification and slow freezing techniques for the cryopreservation of zebrafish ovarian tissue containing immature follicles. In Experiment 1, assessment of cell membrane integrity by trypan blue exclusion staining was used to select the best cryoprotectant solution for each cryopreservation method. Primary growth (PG) oocytes showed the best percentage of membrane integrity (63.5 ± 2.99%) when SF4 solution (2 M methanol + 0.1 M trehalose + 10% egg yolk solution) was employed. The vitrification solution, which presented the highest membrane integrity (V2; 1.5 M methanol + 5.5 M Me2SO + 0.5 M sucrose + 10% egg yolk solution) was selected for Experiment 2. Experiment 2 aimed to compare the vitrification and slow freezing techniques in the following parameters: morphology, oxidative stress, mitochondrial activity, and DNA damage. Frozen ovarian tissue showed higher ROS levels and lower mitochondrial activity than vitrified ovarian tissue. Ultrastructural observations of frozen PG oocytes showed rupture of the plasma membrane, loss of intracellular contents and a large number of damaged mitochondria, while vitrified PG oocytes had intact mitochondria and cell plasma membranes. We conclude that vitrification may be more effective than slow freezing for the cryopreservation of zebrafish ovarian tissue.
The aim of this work was to evaluate the effect of the food additives, sodium chloride, sodium metabisulfite, sodium nitrite and citric acid on the anti-melanotic activity in shrimp (Xyphopenaeus kroyeri) kept under refrigeration for 13 days post-capture. A sensory panel and color measurements (L*: luminosity, a*: red-green axis saturation and b*: yellow-blue axis saturation) was conducted during storage to evaluate the development stages of melanosis. Statistical differences were found in the colorimetric indexes (L*, a* and b*) and melanosis levels in all the treatments. The best results were found in 2.5% sodium metabisulfite. However, 2% sodium chloride had similar results and presented advantages such as low cost, maintaining firmness, general appearance, flavor, microbiological control, besides not causing allergic reactions. The sodium chloride is an excellent alternative to sodium metabisulfite.
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