Gnathonemus petersii (Gunther, 1862)

Ozouf-Costaz, Catherine, Coutanceau, Jean-Pierre, Bonillo, Céline, Belkadi, Laurent, Fermon, Yves, Agnese, Jean-François, Guidi-Rontani, Chantal & Paugy, Didier, 2015, First insights into karyotype evolution within the family Mormyridae, Cybium 39 (3), pp. 227-236 : 231

Gnathonemus petersii

The karyotype is composed of 2n = 48 chromosomes (2sm + 18 m + 28a), FN = 68. C-bands are small and essentially located in centromeric regions but at least four chromosome pairs also exhibit intercalated bands in their long arms, in particular the large (sm) pair, and several acrocentric pairs ( Fig. 3 ). In several metaphase plates, the 18S rDNA genes could be localized in pericentromeric position in a large sm chromosome and not in its homologous ( Fig. 4A, B ). The telomeric probe hybridized on almost all chromosomes, but generally not at their four telomeres. No interstitial telomeric signal (ITS) could be recorded ( Fig. 4C ). The microsatellite (GAA) 10 is abundant and mainly located in telomeric positions with an intercalary band in pericentromeric position in the large sm pair ( Fig. 4D ).

Figures

Figure 3. - Karyotypes of G. petersii, GNPE, M. moorii, MAMO, I. opdenboschi, IVOP, Brienomyrus sp., BR SP, S. walkeri, STWA, and P. microphthalmus, PEMI, after conventional Giemsa staining and C-banding. Scale bar = 10 µm.

Figure 4. - Metaphase plates of G. petersii (A, B, C, D), M. moorii (E, F, G, H) and I. opdenboschi (I, J, K, L), showing FISH patterns of the 18S rDNA probe, indirectly DIG-labelled, detected with rhodamine; DAPI counterstaining on the same metaphase plate; patterns of the Atto 488 labeled (TTAGGG)7 probe; patterns of the Cy3 labeled (GAA)10 satellite probe. Scale bars = 10 µm.