Marie Altmanová

• PhD.
• Researcher at Charles University in Prague

Background: Tandemly repeated satellite DNA sequences are an important part of animal genomes. They are involved in chromosome interactions and the maintenance of the integral structure of the nucleus, regulation of chromatin conformation and gene expression, and chromosome condensation and movement during cell division. Satellite DNAs located in t...

Obligatory parthenogenesis in vertebrates is restricted to squamate reptiles and evolved through hybridisation. Parthenogens can hybridise with sexual species, resulting in individuals with increased ploidy levels. We describe two successive hybridisations of the parthenogenetic butterfly lizards (genus Leiolepis) in Vietnam with a parental sexual...

Among vertebrates, obligate parthenogenesis occurs exclusively in squamate reptiles. Premeiotic endoreplication in a small subset of developing oocytes has been documented as the mechanism of production of unreduced eggs in minutely explored obligate parthenogenetic lineages, namely in teiids and geckos. The situation in the lacertid genus Darevski...

Sex chromosomes of teleost fishes often have low levels of differentiation and undergo frequent turnovers. Annual Nothobranchius killifishes comprise representatives with male-heterogametic XY or X1X2Y sex chromosome systems, scattered across their phylogeny, nested within species lacking cytologically detectable sex chromosomes. They thus provide...

Among vertebrates, obligate parthenogenesis occurs exclusively in squamate reptiles. Premeiotic endoreplication in a small subset of developing oocytes has been documented as the mechanism of production of unreduced eggs in minutely explored obligate parthenogenetic lineages, namely in teiids and geckos. The situation in the lacertid genus Darevski...

Chameleons are well-known lizards with unique morphology and physiology, but their sex determination has remained poorly studied. Madagascan chameleons of the genus Furcifer have cytogenetically distinct Z and W sex chromosomes and occasionally Z1Z1Z2Z2/Z1Z2W multiple neo-sex chromosomes. To identify the gene content of their sex chromosomes, we mi...

Background Crocodilians are one of the oldest extant vertebrate lineages, exhibiting a combination of evolutionary success and morphological resilience that has persisted throughout the history of life on Earth. This ability to endure over such a long geological time span is of great evolutionary importance. Here, we have utilized the combination o...

Karyotype divergence may strongly affect the degree of hybridization between species. Western Palearctic slow worms (Anguis) are legless lizards forming different types of secondary contact zones. To identify the level of chromosomal variation in slow worms, we examined karyotype in multiple populations of all species except one and Pseudopus apodu...

Chameleons are well-known lizards with unique morphology and physiology, but their sex determination has remained poorly studied. Madagascan chameleons of the genus Furcifer have cytogenetically distinct Z and W sex chromosomes and occasionally Z 1 Z 1 Z 2 Z 2 /Z 1 Z 2 W multiple neo-sex chromosomes. To identify the gene content of their sex chromo...

Satellite DNA (satDNA) is a rapidly evolving class of tandem repeats, with some monomers being involved in centromere organization and function. To identify repeats associated with (peri)centromeric regions, we investigated satDNA across Southern and Coastal clades of African annual killifishes of the genus Nothobranchius. Molecular cytogenetic and...

Meiosis is a conservative process in all sexual organisms which ensures fertility and is central for producing genetic diversity by recombination and random segregation of parental chromosomes. Yet unexplored mechanisms may disrupt it and cause loss of sex followed by the emergence of clonal modes of reproduction. Interspecific hybridization is the...

Using African annual killifishes of the genus Nothobranchius from temporary savannah pools with rapid karyotype and sex chromosome evolution, we analysed the chromosomal distribution of telomeric (TTAGGG)n repeat and Nfu‐SatC satellite DNA (satDNA; isolated from Nothobranchius furzeri) in 15 species across the Nothobranchius killifish phylogeny, an...

Crocodilians have maintained very similar karyotype structures and diploid chromosome numbers for around 100 million years, with only minor variations in collinearity. Why this karyotype structure has largely stayed unaltered for so long is unclear. In this study, we analyzed the karyotypes of six species belonging to the genera Crocodylus and Oste...

Crocodilians are one of the oldest extant vertebrate lineages, which exhibits a combination of evolutionary success and morphological resilience that have persisted throughout the history of life on Earth. Such an ability to endure over such a long geological time span is of great evolutionary importance. Here, we performed a comprehensive analysis...

There is a growing need of alternative experimental models that avoid or minimize the use of animals due to ethical, economical, and scientific reasons. Surprisingly, the stable embryonic cell lines representing Nothobranchius spp., emerging vertebrate models in aging research, regenerative medicine, ecotoxicology, or genomics, have been not derive...

Repetitive DNA may have significant impact on genome evolution. African annual killifishes of the genus Nothobranchius (Teleostei: Nothobranchiidae), which has adapted to temporary water pools in African savannahs, possess genomes with high repeat content. They are also characterized by rapid karyotype and sex chromosome evolution but the role of g...

Satellite DNA (satDNA) is rapidly evolving class of tandem repeats with some motifs being involved in centromere organization and function. Rapid co-evolution of centromeric satDNA and associated proteins has been mostly attributed to the so-called centromere drive. To identify repeats associated with centromeric regions and test for the role of me...

Karyotype divergence may strongly affect the rate of hybridization between species in their secondary contact zones. Slow worms ( Anguis , Anguidae) are morphologically relatively cryptic legless lizards representing two evolutionary lineages, A. cephallonica from the southernmost Balkans, and the A. fragilis species complex (comprising two sister-...

Homomorphic sex chromosomes and their turnover are common in teleosts. We investigated the evolution of nascent sex chromosomes in several populations of two sister species of African annual killifishes, Nothobranchius furzeri and N. kadleci, focusing on their under-studied repetitive landscape. We combined bioinformatic analyses of the repeatome w...

Obligate parthenogenesis evolved in reptiles convergently several times, mostly through interspecific hybridization. The obligate parthenogenetic complexes typically include both diploid and triploid lineages. Offspring of the parthenogenetic hybrids are genetic copies of their mothers; however, the cellular mechanism enabling the production of unr...

Repetitive DNA represents an important driver of sex chromosome differentiation. Yet, repetitive sequences tend to be misrepresented or overlooked in genomic studies. We analysed repetitive DNA landscape of sex chromosomes in several populations of a turquoise killifish Nothobranchius furzeri and its sister species N. kadleci (Teleostei: Nothobranc...

Changes in chromosomal structure involving chromosomal rearrangements or copy number variation of specific sequences can play an important role in speciation. Here, we explored the chromosomal structure of two hybridizing passerine species; the common nightingale (Luscinia megarhynchos) and the thrush nightingale (Luscinia luscinia), using conventi...

Transitions from environmental sex determination (ESD) to genotypic sex determination (GSD) require an intermediate step of sex reversal, i.e., the production of individuals with a mismatch between the ancestral genotypic and the phenotypic sex. Among amniotes, the sole well-documented transition in this direction was shown in the laboratory in the...

Despite decades of cytogenetic and genomic research of dynamic sex chromosome evolution in teleost fishes, multiple sex chromosomes have been largely neglected. In this review, we compiled available data on teleost multiple sex chromosomes, identified major trends in their evolution and suggest further trajectories in their investigation. In a comp...

Although crocodilians have attracted enormous attention in other research fields, from the cytogenetic point of view, this group remains understudied. Here, we analyzed the karyotypes of eight species formally described from the Alligatoridae family using differential staining, fluorescence in situ hybridization with rDNA and repetitive motifs as a...

Dragon lizards (Squamata: Agamidae) comprise about 520 species in six subfamilies distributed across Asia, Australasia and Africa. Only five species are known to have sex chromosomes. All of them possess ZZ/ZW sex chromosomes, which are microchromosomes in four species from the subfamily Amphibolurinae, but much larger in Phrynocephalus vlangalii f...

Dragon lizards (Squamata: Agamidae) comprise about 520 species in six subfamilies distributed across Asia, Australasia and Africa. Only five species are known to have sex chromosomes. All of them possess ZZ/ZW sex chromosomes, which are microchromosomes in four species from the subfamily Amphibolurinae, but much larger in Phrynocephalus vlangalii f...

Lacertid lizards are a widely radiated group of squamate reptiles with long-term stable ZZ/ZW sex chromosomes. Despite their family-wide homology of Z-specific gene content, previous cytogenetic studies revealed significant variability in the size, morphology, and heterochromatin distribution of their W chromosome. However, there is little evidence...

Chameleons are well-known, highly distinctive lizards characterized by unique morphological and physiological traits, but their karyotypes and sex determination system have remained poorly studied. We studied karyotypes in six species of Madagascan chameleons of the genus Furcifer by classical (conventional stain, C-banding) and molecular (comparat...

Homologous and differentiated ZZ/ZW sex chromosomes (or derived multiple neo-sex chromosomes) were often described in caenophidian snakes, but sex chromosomes were unknown until recently in non-caenophidian snakes. Previous studies revealed that two species of boas (Boa imperator, B. constrictor) and one species of python (Python bivittatus) indepe...

Monitor lizards are unique among ectothermic reptiles in that they have high aerobic capacity and distinctive cardiovascular physiology resembling that of endothermic mammals. Here, we sequence the genome of the Komodo dragon Varanus komodoensis, the largest extant monitor lizard, and generate a high-resolution de novo chromosome-assigned genome as...

Amniotes possess variability in sex determination, ranging from environmental sex determination to genotypic sex determination with differentiated sex chromosomes. Differentiated sex chromosomes have emerged independently several times. Their noteworthy convergent characteristic is the evolutionary stability, documented among amniotes in mammals, b...

An experimental approach using monoclonal anti-5-methylcytosine antibodies and indirect immunofluorescence was elaborated for detecting 5-methylcytosine-rich chromosome regions in reptilian chromosomes. This technique was applied to conventionally prepared mitotic metaphases of 2 turtle species and 12 squamate species from 8 families. The hypermeth...

We developed new tools to build a high-quality chromosomal map of the Komodo dragon ( Varanus komodoensis ) available for cross-species phylogenomic analyses. First, we isolated chromosomes by flow sorting and determined the chromosome content of each flow karyotype peak by FISH. We then isolated additional Komodo dragon chromosomes by microdissect...

Despite their long history with the basal split dating back to the Eocene, all species of monitor lizards (family Varanidae) studied so far share the same chromosome number of 2n = 40. However, there are differences in the morphology of the macrochromosome pairs 5–8. Further, sex determination, which revealed ZZ/ZW sex microchromosomes, was studied...

The advanced snakes (Caenophidia), the important amniote lineage encompassing more than 3000 living species, possess highly conserved female heterogamety across all families. However, we still lack any knowledge on the gene(s) and the molecular mechanism controlling sex determination. Triploid individuals spontaneously appear in populations of dipl...

Snakes are historically important in the formulation of several central concepts on the evolution of sex chromosomes. For over 50 years, it was believed that all snakes shared the same ZZ/ZW sex chromosomes, which are homomorphic and poorly differentiated in “basal” snakes such as pythons and boas, while heteromorphic and well differentiated in “ad...

Polyploidization has played an important role in the evolution of vertebrates, particularly at the base of Teleostei–an enormously successful ray-finned fish group with additional genome doublings on lower taxonomic levels. The investigation of post-polyploid genome dynamics might provide important clues about the evolution and ecology of respectiv...

FISH with 5S rDNA and U2 snDNA probes in the rest of examined botiid species. U2 snDNA (red, arrows) and 5S rDNA (green, arrowheads) probes (B,F,H) or a single U2 snDNA (red, arrows) probe (A,C,D,E,G) mapped on (A) B. almorhae, (B) Ch. macracanthus, (C) L. elongata, (D) L. guilinensis, (E) P. fasciatus, (F) S. pulchra, (G) S. superciliaris, (H) S....

PNA FISH with telomeric probe in the rest of examined botiid species. (A) B. udomritthiruji, (B) S. pulchra, (C) S. superciliaris, (D) S. zebra, (E) Y. lecontei. For better contrast, pictures were pseudocoloured in green (telomeric repeat probe) and red (DAPI). For better distinction between individual chromosomes, we included also the separate ima...

Selected sequential experiments clarifying conjugated or independent location of distinct cytogenetic markers. Metaphases are arranged sequentially in Ch. macracanthus (A,D), L. elongata (B,E), L. guilinensis (C,F), L. microphthalma (G,I) and S. superciliaris (H,J) after CMA3/DAPI staining (D,E,F,I,J) and corresponding dual-colour FISH with 28S rDN...

Karyotype and mitotic chromosomes of B. dario after different cytogenetic protocols. (A) Karyotype arranged from Giemsa-stained chromosomes, (B) CMA3/DAPI staining. (C) Dual-colour FISH with 28S rDNA (red, arrows) and 5S rDNA (green, arrowheads) probes. (D) Uni-colour FISH with U2 snDNA (red, arrows) probe. (E) PNA FISH with telomeric probe. Due to...

CMA3/DAPI staining in the rest of examined botiid species. (A) B. udomritthiruji, (B) L. elongata, (C) P. fasciatus, (D) S. superciliaris, (E) S. zebra, (F) Y. lecontei. For better contrast, pictures were pseudocoloured in red (for CMA3) and green (for DAPI). Open arrows indicate CMA3-positive sites. The metaphase spread of S. superciliaris (D) is...

Dual-colour (5S/45S) rDNA FISH in the rest of examined botiid species. 28S rDNA (red, arrows) and 5S rDNA (green, arrowheads) probes mapped on (A) L. elongata, (B) L. microphthalma, (C) S. superciliaris, (D) S. zebra, (E) Y. lecontei. Chromosomes were counterstained with DAPI (blue). Note the significant spreading of 5S rDNA sites in Y. lecontei (E...

The reconstruction of the evolutionary dynamics of karyotypes and sex determining systems in squamate reptiles is precluded by the lack of data in many groups including most chameleons (Squamata: Acrodonta: Chamaeleonidae). We performed cytogenetic analysis in 16 species of chameleons from 8 genera covering the phylogenetic diversity of the family...

Once believed to be restricted only to endotherms (mammals and birds), several poikilothermic amniote lineages have recently been documented to possess long-term evolutionary stability in their sex chromosomes. However, many important lineages were not included in these tests. Previously, based on molecular evidence, we documented the homology of w...

Advanced snakes (Caenophidia) are an important group including around 90% of the recent species of snakes. The basal splitting of the clade is still rather controversial, and it is not fully understood when the differentiation of sex chromosomes started in snake evolution. To help resolve these questions, we performed cytogenetic analysis on the Ja...

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 o...

The Komodo dragon (Varanus komodoensis) is the largest lizard in the world. Surprisingly, it has not yet been cytogenetically examined. Here, we present the very first description of its karyotype and sex chromosomes. The karyotype consists of 2n = 40 chromosomes, 16 macrochromosomes and 24 microchromosomes. Although the chromosome number is consta...

Iguanas (Pleurodonta) are predominantly distributed in the New World, but one previously cytogenetically understudied family, Opluridae, is endemic to Madagascar and the adjacent Grand Comoro archipelago. The aim of our contribution is to fill a gap in the cytogenetic understanding of this biogeographically puzzling lineage. Based on examination of...

Sex chromosomes are believed to be stable in endotherms, but young and evolutionary unstable in most ectothermic vertebrates. Within lacertids, the widely radiated lizard group, sex chromosomes have been reported to vary in morphology and heterochromatinization, which may suggest turnovers during the evolution of the group. We compared the partial...

Background: Loaches of the family Nemacheilidae are one of the most speciose elements of Palearctic freshwater ichthyofauna and have undergone rapid ecological adaptations and colonizations. Their cytotaxonomy is largely unexplored; with the impact of cytogenetical changes on this evolutionary diversification still unknown. An extensive cytogeneti...

Amniotes possess variability in sex determining mechanisms, however, this diversity is still only partially known throughout the clade and sex determining systems still remain unknown even in such a popular and distinctive lineage as chameleons (Squamata: Acrodonta: Chamaeleonidae). Here, we present evidence for female heterogamety in this group. T...

Amniotes possess variability in sex determining mechanisms, however, this diversity is still only partially known throughout the clade and sex determining systems still remain unknown even in such a popular and distinctive lineage as chameleons (Squamata: Acrodonta: Chamaeleonidae). Here, we present evidence for female heterogamety in this group. T...

Telomeres are nucleoprotein complexes protecting the physical ends of linear eukaryotic chromosomes and therefore helping to ensure their stability and integrity. Additionally, telo-meric sequences can be localized in non-terminal regions of chromosomes, forming so-called interstitial telomeric sequences (ITSs). ITSs are traditionally considered to...

The green anole, Anolis carolinensis (ACA), is the model reptile for a vast array of biological disciplines. It was the first non-avian reptile to have its genome fully sequenced. During the genome project, the XX/XY system of sex chromosomes homologous to chicken chromosome 15 (GGA15) was revealed and 106 X-linked genes were identified. We selecte...

Among amniote vertebrates, geckos represent a clade with exceptional variability in sex determination; however, only a minority of species of this highly diverse group has been studied in this respect. Here, we describe for the first time a female heterogamety in the genus Paroedura, the group radiated in Madagascar and adjacent islands. We identif...

Numbers of identified independent origins of multiple sex chromosomes, numbers of species with known multiple neo-sex chromosomes, numbers of karyotyped species and numbers of species with known sex chromosomes across amniote lineages

List of species with multiple sex chromosomes

Many poikilothermic vertebrate lineages, especially among amphibians and fishes, possess a rapid turnover of sex chromosomes, while in endotherms there is a notable stability of sex chromosomes. Reptiles in general exhibit variability in sex-determining systems; as typical poikilotherms, they might be expected to have a rapid turnover of sex chromo...

It is notable that the occurrence of multiple sex chromosomes differs significantly between major lineages of amniote vertebrates. In this respect, birds are especially conspicuous, as multiple sex chromosomes have not been observed in this lineage so far. On the other hand, in mammals, multiple sex chromosomes have evolved many times independently...

Vertebrates possess diverse sex determining systems, which differ in evolutionary stability among particular groups. It has been suggested that poikilotherms possess more frequent turnovers of sex chromosomes than homoiotherms, whose effective thermoregulation can prevent the emergence of the sex-reversals induced by environmental temperature. Squa...