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Zoological Research
Kunming Institute of Zoology, Chinese Academy of Sciences
ISSN: 2095-8137
Vol. 32, No. 5, 2011, pp. 521-527
Bioline Code: zr11074
Full paper language: Chinese
Document type: Research Article
Document available free of charge

Zoological Research, Vol. 32, No. 5, 2011, pp. 521-527

 en Possible genetic reproductive isolation between two tilapiine genera and species: Oreochromis niloticus check for this species in other resources and Sarotherodon melanotheron check for this species in other resources
LI, Si-Fa; ZHAO, Yan; FAN, Wu-Jiang; CAI, Wan-Qi & XU, Ying-Fang

Abstract

Successful crossbreeding between Oreochromis niloticus check for this species in other resources and Sarotherodon melanotheron check for this species in other resources to produce a commercial hybrid has been difficult. The karyotypes and isoenzyme of these two species and their reciprocal hybrids (O. niloticus ♀ × S. melanotheron ♂, S. melanotheron ♀ × O. niloticus ♂, the last not included in the isoenzyme study) were investigated via metaphase chromosomes obtained from head kidney cells and electropherogram of lactate dehydrogenase (LDH) isoenzymes from the liver, kidney, white muscle, heart, and eye balls. The diploid chromosome number (2n=44) and the fundamental number (NF=50) of the four tilapia genotypes were the same. However, the karyotype of O. niloticus had three pairs of sub-metacentric (sm), twelve pairs of sub-telocentric (st), and seven pairs of telocentric (t) chromosomes, while S. melanotheron had one pair of metacentric (m), two pairs of sm, 12 pairs of st, and seven pairs of t chromosomes. The reciprocal hybrids both showed a mixed karyotype range between their parents: 0.5 pair of m, 2.5 pairs of sm, 12 pairs of st, and seven pairs of t chromosomes. In view of the electropherogram of isozymes, only the LDH of the kidney showed significant clear bands, with five bands in O. niloticus, three bands in S. melanotheron, and duplicated six bands in the hybrids. The bands varied depending on their activities and mobilities. We considered that the differences in karyotype and isoenzyme were related to the genetic mechanism for post-mating isolation, and provided some additional basic genetic background of their taxonomy.

Keywords
Tilapiine, Oreochromis niloticus, Sarotherodon melanotheron, Karyotype, Isoenzyme, Reproductive isolation, Taxonomy

 
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