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Comparative Chromosome Painting and NOR Distribution Suggest a Complex Hybrid Origin of Triploid Lepidodactylus lugubris (Gekkonidae).

Trifonov VA, Paoletti A, Caputo Barucchi V, Kalinina T, O'Brien PC, Ferguson-Smith MA, Giovannotti M - PLoS ONE (2015)

Bottom Line: Also, we applied a 28S ribosomal DNA probe and Ag-staining to detect nucleolus organizer regions (NORs).The NORs were found to be located on one out of three homologs on each of LLU8, LLU15 and LLU18, thus further confirming a hybrid origin of triploid individuals.The pattern of NOR localizations and homologous regions in males and females, as well as the absence of other detectable karyotypic differences, suggest that males arise spontaneously in all female populations and do not arise from independent hybridizations with different species.

View Article: PubMed Central - PubMed

Affiliation: Institute of Molecular and Cellular Biology SB RAS, Novosibirsk, Russia; Novosibirsk State University, Novosibirsk, Russia.

ABSTRACT
Parthenogenesis, unisexuality and triploidy are interesting but poorly studied phenomena occurring in some reptile species. The mourning gecko (Lepidodactylus lugubris) represents a complex of diploid and triploid parthenogenetic mostly all-female populations (males occur quite rarely) widely distributed in coastal areas of the Indian and Pacific Oceans. Here, we study karyotypes of a male and two female L. lugubris (LLU) triploid individuals (3n = 66) using comparative painting with Gekko japonicus, Hemidactylus turcicus and H. platyurus chromosome specific probes to visualize the homologous regions and to reveal genus specific rearrangements. Also, we applied a 28S ribosomal DNA probe and Ag-staining to detect nucleolus organizer regions (NORs). Our results suggest that the karyotype of L. lugubris underwent a chromosome fission and a fusion after its divergence from a common ancestor of the Gekko-Hemidactylus group. The NORs were found to be located on one out of three homologs on each of LLU8, LLU15 and LLU18, thus further confirming a hybrid origin of triploid individuals. It seems that three different bisexual populations might have contributed to the origin of this triploid parthenogenetic population. We postulate that the heterozygosity in NOR localization is maintained in the triploid clone studied by the absence of recombination as described in whiptail lizards. The pattern of NOR localizations and homologous regions in males and females, as well as the absence of other detectable karyotypic differences, suggest that males arise spontaneously in all female populations and do not arise from independent hybridizations with different species.

No MeSH data available.


Related in: MedlinePlus

AgNOR staining of Lepidodactylus lugubris chromosomes.(A) LLU female B and (B) LLU male D. There is a polymorphism in NOR activity revealed by Ag-staining: only a single chromosome carries an active NOR in female B, but all three NORs are revealed in male D. Scale bar, 10 μm.
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pone.0132380.g005: AgNOR staining of Lepidodactylus lugubris chromosomes.(A) LLU female B and (B) LLU male D. There is a polymorphism in NOR activity revealed by Ag-staining: only a single chromosome carries an active NOR in female B, but all three NORs are revealed in male D. Scale bar, 10 μm.

Mentions: AgNOR staining revealed some variability in the number of active NOR sites. In particular, a single active NOR on LLU15p was detected in females A, B and in the male A, whereas three active NORs were detected in the other three males (B, C and D) on LLU8q, LLU15p and LLU18p (Fig 5).


Comparative Chromosome Painting and NOR Distribution Suggest a Complex Hybrid Origin of Triploid Lepidodactylus lugubris (Gekkonidae).

Trifonov VA, Paoletti A, Caputo Barucchi V, Kalinina T, O'Brien PC, Ferguson-Smith MA, Giovannotti M - PLoS ONE (2015)

AgNOR staining of Lepidodactylus lugubris chromosomes.(A) LLU female B and (B) LLU male D. There is a polymorphism in NOR activity revealed by Ag-staining: only a single chromosome carries an active NOR in female B, but all three NORs are revealed in male D. Scale bar, 10 μm.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4492922&req=5

pone.0132380.g005: AgNOR staining of Lepidodactylus lugubris chromosomes.(A) LLU female B and (B) LLU male D. There is a polymorphism in NOR activity revealed by Ag-staining: only a single chromosome carries an active NOR in female B, but all three NORs are revealed in male D. Scale bar, 10 μm.
Mentions: AgNOR staining revealed some variability in the number of active NOR sites. In particular, a single active NOR on LLU15p was detected in females A, B and in the male A, whereas three active NORs were detected in the other three males (B, C and D) on LLU8q, LLU15p and LLU18p (Fig 5).

Bottom Line: Also, we applied a 28S ribosomal DNA probe and Ag-staining to detect nucleolus organizer regions (NORs).The NORs were found to be located on one out of three homologs on each of LLU8, LLU15 and LLU18, thus further confirming a hybrid origin of triploid individuals.The pattern of NOR localizations and homologous regions in males and females, as well as the absence of other detectable karyotypic differences, suggest that males arise spontaneously in all female populations and do not arise from independent hybridizations with different species.

View Article: PubMed Central - PubMed

Affiliation: Institute of Molecular and Cellular Biology SB RAS, Novosibirsk, Russia; Novosibirsk State University, Novosibirsk, Russia.

ABSTRACT
Parthenogenesis, unisexuality and triploidy are interesting but poorly studied phenomena occurring in some reptile species. The mourning gecko (Lepidodactylus lugubris) represents a complex of diploid and triploid parthenogenetic mostly all-female populations (males occur quite rarely) widely distributed in coastal areas of the Indian and Pacific Oceans. Here, we study karyotypes of a male and two female L. lugubris (LLU) triploid individuals (3n = 66) using comparative painting with Gekko japonicus, Hemidactylus turcicus and H. platyurus chromosome specific probes to visualize the homologous regions and to reveal genus specific rearrangements. Also, we applied a 28S ribosomal DNA probe and Ag-staining to detect nucleolus organizer regions (NORs). Our results suggest that the karyotype of L. lugubris underwent a chromosome fission and a fusion after its divergence from a common ancestor of the Gekko-Hemidactylus group. The NORs were found to be located on one out of three homologs on each of LLU8, LLU15 and LLU18, thus further confirming a hybrid origin of triploid individuals. It seems that three different bisexual populations might have contributed to the origin of this triploid parthenogenetic population. We postulate that the heterozygosity in NOR localization is maintained in the triploid clone studied by the absence of recombination as described in whiptail lizards. The pattern of NOR localizations and homologous regions in males and females, as well as the absence of other detectable karyotypic differences, suggest that males arise spontaneously in all female populations and do not arise from independent hybridizations with different species.

No MeSH data available.


Related in: MedlinePlus