Synaptonemal Complex of Two Fish Species of the genus Nothobranchius (Cyprinodontidae)

The karyotype of males of two species of the genus Nothobranchius with the lowest diploid numbers was investigated: Nothobranchius rachovi (2N = 16) and Nothobranchius krysanovi (2N = 18). For the first time, whole mounts of spread syneptonemal complexes (SC) of these species were obtained and investigated. When the SC was painted with silver nitrate and immunostained with rabbit antibodies against the SCP3 protein, eight and nine homomorphic SCs were detected in the nuclei of class I spermatocytes of N. krysanovi and N. rachovi, respectively. The sex chromosomes were not identified.