title: Chilling curves for Piaractus mesopotamicus (Holmberg, 1887) embryos stored at -8°C.
abstract: The present study investigates the effect of different slow chilling curves on the storage of pacu (Piaractus mesopotamicus) embryos submitted to chilling at -8°C. Embryos at the blastopore closure stage were divided into two groups: G1 - embryos exposed to cryoprotectant solution containing methanol (10%) and sucrose (0.5 M), treated as follows: (T1) taken directly from room temperature to the refrigerator without being submitted to the curve; (T2) chilling curve of 0.5°C/min; and (T3) chilling curve of 1°C/min; and G2 - the cryoprotectant solution alone was submitted to these same temperatures, receiving the embryos only after temperature had decreased, corresponding to treatments T4, T5 and T6, respectively. Treatments were kept at -8°C for a period of 6 h. Embryo development was evaluated for each treatment, with six replicates in an entirely randomized design. Survival among embryos not submitted to refrigeration was 94.3 ± 8.05%. Percentage of total larvae (TL) and addled eggs (AE) did not differ statistically between the groups, although percentage of swimming larvae (SL) exhibited higher values in G1 for the 1°C/min curve. Furthermore, when comparing the three chilling curves, a decrease of 1°C/min resulted in the highest TL percentage (90.85%), followed by the 0.5°C/min curve (78.52%). Thus, the use of 1°C/min chilling curves is recommended for P. mesopotamicus embryos stored for 6 h at -8°C.
authors.affiliation: Aquaculture Centre, São Paulo State University (UNESP), Via de Acesso Prof. Paulo Donato Castellane, s/n, CEP 14884-900, Jaboticabal, SP, Brazil.
authors.forename: Taís da S
authors.initials: Tda S
authors.lastname: Lopes
authors.forename: Danilo Pedro
authors.initials: DP
authors.lastname: Streit
authors.forename: Darci Carlos
authors.initials: DC
authors.lastname: Fornari
authors.forename: Diego
authors.initials: D
authors.lastname: de Oliveira
authors.forename: Ricardo Pereira
authors.initials: RP
authors.lastname: Ribeiro
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Romagosa
mesh_terms: D000818:Animals; D002470:Cell Survival; D060126:Characidae / Q000196:embryology*; D003080:Cold Temperature; D015925:Cryopreservation; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000502:physiology*; D047108:Embryonic Development; D007814:Larva / Q000254:growth & development; D013997:Time Factors