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Comparative cytogenetics in ancestral teleost fishes: karyotype characterisation from two species of Australian Saratoga, Scleropages leichardti and Scleropages jardini (Osteoglossidae)

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Despite substantial progress fish cytogenetics, there are still several gaps in our knowledge about genome evolution and organization in one of the early branching lineages of teleosts - the Osteoglossomorpha. Here, we present comparative cytogenetic study of its two Sahulan species Scleropages leichardti (Günther, 1864) and S. jardinii (Saville-Kent, 1892). To characterise their karyotypes we applied both conventional (Giemsa staining, C-banding, Ag-NOR staining and CMA3/DAPI fluorescence) and molecular (FISH with rDNA and microsatellite probes, CGH) cytogenetics techniques. Karyotype analyses showed differences in diploid chromosome number between S. leichardti (2n = 44) and S. jardinii (2n = 48), with morphology and variability on the sub-chromosomal level, such as different accumulation of heterochromatin. Moreover, we uncovered heterogeneous composition of AT/GC rich regions on chromosomes of both species. Among actinopterygians, cytogenetically detectable AT/GC heterogeneity has so far only been documented in gars (Lepisosteiformes, another early branching teleost lineage). We argue that this genome feature is ancestral to all teleosts and has been lost in most recent lineages. Our data provided valuable insights into early karyotype evolution and genome compartmentalization in actinopterygians.

Acknowledgements: The study has been supported by the project No. MSM200451701 from the Czech Academy of Sciences and by CAPES/Alexander von Humboldt Foundation (Process 88881.136128/2017-01) and the project EXCELLENCE CZ.02.1.01/0.0/0.0/15_003/0000460 OP RDE and RVO: 67985904.

Jul 05, 2018 11:30 AM - 11:45 AM(UTC)
Venue : 2B7 - Building 2
20180705T1130 20180705T1145 UTC Comparative cytogenetics in ancestral teleost fishes: karyotype characterisation from two species of Australian Saratoga, Scleropages leichardti and Scleropages jardini (Osteoglossidae)

Despite substantial progress fish cytogenetics, there are still several gaps in our knowledge about genome evolution and organization in one of the early branching lineages of teleosts - the Osteoglossomorpha. Here, we present comparative cytogenetic study of its two Sahulan species Scleropages leichardti (Günther, 1864) and S. jardinii (Saville-Kent, 1892). To characterise their karyotypes we applied both conventional (Giemsa staining, C-banding, Ag-NOR staining and CMA3/DAPI fluorescence) and molecular (FISH with rDNA and microsatellite probes, CGH) cytogenetics techniques. Karyotype analyses showed differences in diploid chromosome number between S. leichardti (2n = 44) and S. jardinii (2n = 48), with morphology and variability on the sub-chromosomal level, such as different accumulation of heterochromatin. Moreover, we uncovered heterogeneous composition of AT/GC rich regions on chromosomes of both species. Among actinopterygians, cytogenetically detectable AT/GC heterogeneity has so far only been documented in gars (Lepisosteiformes, another early branching teleost lineage). We argue that this genome feature is ancestral to all teleosts and has been lost in most recent lineages. Our data provided valuable insights into early karyotype evolution and genome compartmentalization in actinopterygians.

Acknowledgements: The study has been supported by the project No. MSM200451701 from the Czech Academy of Sciences and by CAPES/Alexander von Humboldt Foundation (Process 88881.136128/2017-01) and the project EXCELLENCE CZ.02.1.01/0.0/0.0/15_003/0000460 OP RDE and RVO: 67985904.

2B7 - Building 2 GSA2018_APCC6 GSACC62018@canberra.edu.au
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Laboratory of Fish Genetics, Institute of Animal Physiology and Genetics, Czech Academy of Sciences, Czech Republic
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