Short communication. Evaluation of presumptive caudal fin blastema cells as candidate donors in intraspecies zebrafish (Danio rerio) chimaeras

The blastema is a regenerative tissue with remarkable pluripotency. The aim of this work done on zebrafish (Danio rerio) was to define technical procedures required for obtaining and integrating blastema cells into embryos at the mid blastula transition stage (MBT) and the effect on survival, as well as the capacity to produce pigmented chimaeras. Wild type blastema cells were injected into gold type MBT embryos (E). Wild MBT blastomere cells were also injected into gold type MBT embryos as a control (C1). A second control group, C2, was not subjected to any manipulation. Survival was evaluated at 24, 48 and 72 h after performing the chimaerism, and the rate of adult chimaeras evaluated. The results showed significant differences in embryo survival between the E and C1 groups in embryo survival at 24 and 48 h postchimaerism (24 h: E-83.49% vs C1-54.8%, p < 0.05; 48 h: E-98.83% vs C1-85.13%, p < 0.05). There was no significant difference, at any time, between E and C2. The results at 72 h for E and the controls (E-89.41%; C1-84.12% and C2-92.55%) indicate that insertion of blastema cells does not have a negative effect on embryo development. The results in adults (E: 0 chimaeras from 7 specimens; C1: 5 chimaeras from 17 specimens) suggest that the dedifferentiation grade of the blastema cells may not be enough to generate germ-line chimaeras, but their condition of potentially dedifferentiating cells may be an advantage when using them as donor nuclei in somatic cloning by nuclear transplant. Additional key words: biodiversity, chimaerism, embryo, zebrafish.