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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

Example of Gekko japonicus painting probes localization onto chromosomes of Lepidodactylus lugubris.Painting probes specific to chromosomes GJA1 (green) and GJA2 (red) each paints two triplets of LLU (female B) chromosomes: GJA1—LLU3 and LLU16; GJA2 – LLU7 and LLU13. Scale bar, 10 μm.
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pone.0132380.g002: Example of Gekko japonicus painting probes localization onto chromosomes of Lepidodactylus lugubris.Painting probes specific to chromosomes GJA1 (green) and GJA2 (red) each paints two triplets of LLU (female B) chromosomes: GJA1—LLU3 and LLU16; GJA2 – LLU7 and LLU13. Scale bar, 10 μm.

Mentions: We hybridized the full sets of chromosome specific probes of G. japonicus and H. platyurus as well as some H. turcicus probes (HTU16, HTU19+20, and HTU21 were used to resolve some ambiguous results) onto chromosomes of L. lugubris male A, female A and female B. As some of the paint probes contained more than one chromosome, the identification of specific chromosome homologies in some cases required painting with probes from one or other of the three species so that those chromosomes within the probe that were not homologous could be eliminated. Most chromosomes were found to be conserved in toto between L. lugubris, H. platyurus, G. japonicas, and H. turcicus (resulting in three homologs per metaphase painted by the same probe). The probe containing chromosome HPL15 painted the distal part of LLU10 (the same results were obtained using the probe GJA12) (S1 Fig). The probe containing a mixture of chromosomes HPL7, 8, 9, 10 painted four LLU triplets completely (LLU4, 8, 9, 11) and additionally the proximal part of LLU10. The probe containing a mixture of chromosomes GJA7, 8, 9 painted LLU5, 8, 11 and additionally the proximal part of LL10 (S1 Fig). To discriminate a chromosome that underwent fission in LLU, we applied a probe containing chromosomes GJA7 and 8 and found signals only on LLU5 and 11. Thus we concluded that the chromosome homologous to GJA9 (HPL9) underwent fission in LLU. We did not reveal any homology for HPL21 (HTU19). The probes specific to chromosomes GJA1 and GJA2 painted two triplets each in LLU (similar results were obtained in HPL [14]). The probe containing GJA chromosomes 4 and 5 painted three triplets in LLU (LLU1, 6, 20). Results of painting are presented in Table 1, Fig 1A, Fig 2 and S1 Fig.


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)

Example of Gekko japonicus painting probes localization onto chromosomes of Lepidodactylus lugubris.Painting probes specific to chromosomes GJA1 (green) and GJA2 (red) each paints two triplets of LLU (female B) chromosomes: GJA1—LLU3 and LLU16; GJA2 – LLU7 and LLU13. Scale bar, 10 μm.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0132380.g002: Example of Gekko japonicus painting probes localization onto chromosomes of Lepidodactylus lugubris.Painting probes specific to chromosomes GJA1 (green) and GJA2 (red) each paints two triplets of LLU (female B) chromosomes: GJA1—LLU3 and LLU16; GJA2 – LLU7 and LLU13. Scale bar, 10 μm.
Mentions: We hybridized the full sets of chromosome specific probes of G. japonicus and H. platyurus as well as some H. turcicus probes (HTU16, HTU19+20, and HTU21 were used to resolve some ambiguous results) onto chromosomes of L. lugubris male A, female A and female B. As some of the paint probes contained more than one chromosome, the identification of specific chromosome homologies in some cases required painting with probes from one or other of the three species so that those chromosomes within the probe that were not homologous could be eliminated. Most chromosomes were found to be conserved in toto between L. lugubris, H. platyurus, G. japonicas, and H. turcicus (resulting in three homologs per metaphase painted by the same probe). The probe containing chromosome HPL15 painted the distal part of LLU10 (the same results were obtained using the probe GJA12) (S1 Fig). The probe containing a mixture of chromosomes HPL7, 8, 9, 10 painted four LLU triplets completely (LLU4, 8, 9, 11) and additionally the proximal part of LLU10. The probe containing a mixture of chromosomes GJA7, 8, 9 painted LLU5, 8, 11 and additionally the proximal part of LL10 (S1 Fig). To discriminate a chromosome that underwent fission in LLU, we applied a probe containing chromosomes GJA7 and 8 and found signals only on LLU5 and 11. Thus we concluded that the chromosome homologous to GJA9 (HPL9) underwent fission in LLU. We did not reveal any homology for HPL21 (HTU19). The probes specific to chromosomes GJA1 and GJA2 painted two triplets each in LLU (similar results were obtained in HPL [14]). The probe containing GJA chromosomes 4 and 5 painted three triplets in LLU (LLU1, 6, 20). Results of painting are presented in Table 1, Fig 1A, Fig 2 and S1 Fig.

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