simple and multiple sex chromosomes Dotaz Zobrazit nápovědu
Geckos in general show extensive variability in sex determining systems, but only male heterogamety has been demonstrated in the members of their legless family Pygopodidae. In the pioneering study published more than 45 years ago, multiple sex chromosomes of the type X1X1X2X2/X1X2Y were described in Burton's legless lizard (Lialisburtonis) based on conventional cytogenetic techniques. We conducted cytogenetic analyses including comparative genomic hybridization and fluorescence in situ hybridization (FISH) with selected cytogenetic markers in this species and the previously cytogenetically unstudied Papua snake lizard (Lialis jicari) to better understand the nature of these sex chromosomes and their differentiation. Both species possess male heterogamety with an X1X1X2X2/X1X2Y sex chromosome system; however, the Y and one of the X chromosomes are not small chromosomes as previously reported in L. burtonis, but the largest macrochromosomal pair in the karyotype. The Y chromosomes in both species have large heterochromatic blocks with extensive accumulations of GATA and AC microsatellite motifs. FISH with telomeric probe revealed an exclusively terminal position of telomeric sequences in L. jicari (2n = 42 chromosomes in females), but extensive interstitial signals, potentially remnants of chromosomal fusions, in L.burtonis (2n = 34 in females). Our study shows that even largely differentiated and heteromorphic sex chromosomes might be misidentified by conventional cytogenetic analyses and that the application of more sensitive cytogenetic techniques for the identification of sex chromosomes is beneficial even in the classical examples of multiple sex chromosomes.
- MeSH
- hybridizace in situ fluorescenční MeSH
- karyotyp MeSH
- mikrosatelitní repetice genetika MeSH
- plazi genetika MeSH
- pohlavní chromozomy genetika MeSH
- srovnávací genomová hybridizace MeSH
- telomery genetika MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
The Neotropical fish, Hoplias malabaricus, is one of the most cytogenetically studied fish taxon with seven distinct karyomorphs (A-G) comprising varying degrees of sex chromosome differentiation, ranging from homomorphic to highly differentiated simple and multiple sex chromosomes. Therefore, this fish offers a unique opportunity to track evolutionary mechanisms standing behind the sex chromosome evolution and differentiation. Here, we focused on a high-resolution cytogenetic characterization of the unique XX/XY1Y2 multiple sex chromosome system found in one of its karyomorphs (G). For this, we applied a suite of conventional (Giemsa-staining, C-banding) and molecular cytogenetic approaches, including fluorescence in situ hybridization FISH (with 5S and 18S rDNAs, 10 microsatellite motifs and telomeric (TTAGGG) n sequences as probes), comparative genomic hybridization (CGH), and whole chromosome painting (WCP). In addition, we performed comparative analyses with other Erythrinidae species to discover the evolutionary origin of this unique karyomorph G-specific XY1Y2 multiple sex chromosome system. WCP experiments confirmed the homology between these multiple sex chromosomes and the nascent XX/XY sex system found in the karyomorph F, but disproved a homology with those of karyomorphs A-D and other closely related species. Besides, the putative origin of such XY1Y2 system by rearrangements of several chromosome pairs from an ancestral karyotype was also highlighted. In addition, clear identification of a male-specific region on the Y1 chromosome suggested a differential pattern of repetitive sequences accumulation. The present data suggested the origin of this unique XY1Y2 sex system, revealing evidences for the high level of plasticity of sex chromosome differentiation within the Erythrinidae.
- MeSH
- hybridizace in situ fluorescenční MeSH
- karyotyp MeSH
- malování chromozomů MeSH
- mikrosatelitní repetice MeSH
- molekulární evoluce * MeSH
- pohlavní chromozomy genetika MeSH
- repetitivní sekvence nukleových kyselin MeSH
- ryby genetika metabolismus MeSH
- srovnávací genomová hybridizace MeSH
- telomery MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
DNA profilování – včetně určování pohlaví jedince – za pomoci mikrosatelitních markerů je v současnosti běžně užívaná genetická metoda studia člověka. Efektivní technikou produkující genetické údaje je amplifikace několika mikrosatelitních lokusů v jedné PCR reakci. Na tomto místě prezentujeme PCR-multiplex systém pro analýzu čtyř Y-STR polymorfních míst. Jedná se o DYS449, DYS456, DYS458 a DYS464. Tyto lokusy jsme vybrali s ohledem na jejich dokumentovanou vysokou diverzitu v euroamerické populaci (10) a s ohledem na jejich absenci v komerčně dostupných analytických soupravách. Celý PCR-multiplex systém je designován pro fragmentační analýzu metodou kapilárové elektroforézy na semi-automatickém genetickém analyzátoru za použití značení pouze jednou fluorescentní barvou. Hlavními oblastmi využití těchto polymorfismů by měly být forenzní a lidská populační genetika.
DNA profiling – inclusive sex determination – with microsatellite markers is currently a commonly used genetic method of studying humans. An efficient technique of producing the genetic data is amplification of multiple microsatellites in a single PCR reaction. Here we introduce a novel PCRmultiplex system for analysis of four polymorphic Y-STRs. Specifically, these are DYS449, DYS456, DYS458, and DYS464. These loci were chosen because of their reported high diversity in Euroamerican population (10), as well as their absence in the commercial analytical kits at the time of beginning of this study. Our objective was to design this PCR-multiplex for use of fragmentation analysis by electrophoresing samples on a capillary semi-automated genetic analyzer applying only one fluorescent dye. The PCR system we propose, may be notably used in fields such as forensic and human population genetics.
