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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

Localization of ribosomal DNA clusters in the mourning gecko (Lepidodactylus lugubris).A partial metaphase of the LLU male A painted with human rDNA probe. Arrows indicate NORs in p-arms of two small but different in size chromosomes and in the distal part of the q-arm of a large chromosome. Scale bar, 10 μm.
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pone.0132380.g003: Localization of ribosomal DNA clusters in the mourning gecko (Lepidodactylus lugubris).A partial metaphase of the LLU male A painted with human rDNA probe. Arrows indicate NORs in p-arms of two small but different in size chromosomes and in the distal part of the q-arm of a large chromosome. Scale bar, 10 μm.

Mentions: We applied FISH with the human 28S ribosomal probe to detect ribosomal DNA clusters in male A, female A and female B. Our results showed the presence of three blocks in the karyotypes of all animals studied: two larger blocks were localized in p-arms of two small (LLU13-LLU19) acrocentric chromosomes and a smaller signal was detected in the subtelomeric region of a medium size chromosome (LLU6-LLU10). It is noteworthy that all three ribosomal cluster bearing chromosomes differed in size, assuming that only one of three homologs retained the ribosomal block in each case (Fig 3). We applied dual colour FISH with differently labeled GJA or HPL probes and a ribosomal probe to determine the NOR-bearing chromosomes precisely. We found that the largest NOR-bearing chromosome was one of the three LLU8 homologs, while LLU15 and LLU18 (only one homolog of each) carried the block in p-arms (Fig 4 and S2 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)

Localization of ribosomal DNA clusters in the mourning gecko (Lepidodactylus lugubris).A partial metaphase of the LLU male A painted with human rDNA probe. Arrows indicate NORs in p-arms of two small but different in size chromosomes and in the distal part of the q-arm of a large chromosome. Scale bar, 10 μm.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0132380.g003: Localization of ribosomal DNA clusters in the mourning gecko (Lepidodactylus lugubris).A partial metaphase of the LLU male A painted with human rDNA probe. Arrows indicate NORs in p-arms of two small but different in size chromosomes and in the distal part of the q-arm of a large chromosome. Scale bar, 10 μm.
Mentions: We applied FISH with the human 28S ribosomal probe to detect ribosomal DNA clusters in male A, female A and female B. Our results showed the presence of three blocks in the karyotypes of all animals studied: two larger blocks were localized in p-arms of two small (LLU13-LLU19) acrocentric chromosomes and a smaller signal was detected in the subtelomeric region of a medium size chromosome (LLU6-LLU10). It is noteworthy that all three ribosomal cluster bearing chromosomes differed in size, assuming that only one of three homologs retained the ribosomal block in each case (Fig 3). We applied dual colour FISH with differently labeled GJA or HPL probes and a ribosomal probe to determine the NOR-bearing chromosomes precisely. We found that the largest NOR-bearing chromosome was one of the three LLU8 homologs, while LLU15 and LLU18 (only one homolog of each) carried the block in p-arms (Fig 4 and S2 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