Sex chromatin is a conspicuous body that occurs in polyploid nuclei of most lepidopteran females and consists of numerous copies of the W sex chromosome. It is also a cytogenetic tool used to rapidly assess the W chromosome presence in Lepidoptera. However, certain chromosomal features could disrupt the formation of sex chromatin and lead to the false conclusion that the W chromosome is absent in the respective species. Here we tested the sex chromatin presence in 50 species of Geometridae. In eight selected species with either missing, atypical, or normal sex chromatin patterns, we performed a detailed karyotype analysis by means of comparative genomic hybridization (CGH) and fluorescence in situ hybridization (FISH). The results showed a high diversity of W chromosomes and clarified the reasons for atypical sex chromatin, including the absence or poor differentiation of W, rearrangements leading to the neo-W emergence, possible association with the nucleolus, and the existence of multiple W chromosomes. In two species, we detected intraspecific variability in the sex chromatin status and sex chromosome constitution. We show that the sex chromatin is not a sufficient marker of the W chromosome presence, but it may be an excellent tool to pinpoint species with atypical sex chromosomes.

• Klíčová slova
• Geometridae, Lepidoptera, W chromosome, comparative genomic hybridization, intraspecific chromosomal variability, neo-sex chromosomes, sex chromatin, sex chromosome evolution,
• MeSH
• druhová specificita MeSH
• hybridizace in situ fluorescenční MeSH
• karyotyp MeSH
• můry genetika   MeSH
• pohlavní chromozomy genetika   MeSH
• sexchromatin metabolismus   MeSH
• srovnávací genomová hybridizace MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Repetitive DNAs comprise large portion of eukaryote genomes. In genome projects, the assembly of repetitive DNAs is challenging due to the similarity between repeats, which generate ambiguities for alignment. Fluorescence in situ hybridization (FISH) is a powerful technique for the physical mapping of various sequences on chromosomes. This technique is thus very helpful in chromosome-based genome assemblies, providing information on the fine architecture of genomes and their evolution. However, various protocols are currently used for FISH mapping, most of which are relatively laborious and expensive, or work properly only with a specific type of probes or sequences, and there is a need for a universal and affordable FISH protocol. Here we tested a FISH protocol for mapping of different DNA repeats, such as multigene families (rDNAs, U snDNAs, histone genes), satellite DNAs, microsatellites, transposable elements, DOP-PCR products, and telomeric motif (TTAGG)n, on the chromosomes of various insects and other arthropods. Different cell types and stages obtained from diverse tissues were used. The FISH procedure proved high quality and reliable results in all experiments performed. We obtained data on the chromosomal distribution of DNA repeats in representatives of insects and other arthropods. Thus, our results allow us to conclude that the protocol is universal and requires only time adjustment for chromosome/DNA denaturation. The use of this FISH protocol will facilitate studies focused on understanding the evolution and role of repetitive DNA in arthropod genomes.

• Klíčová slova
• Arthropoda, Chromosomes, Cytogenetics, DNA repeats, FISH protocol, Genome structure, Insecta,
• MeSH
• členovci genetika   MeSH
• DNA genetika   MeSH
• fluorescence MeSH
• hmyz genetika   MeSH
• hybridizace in situ fluorescenční metody   MeSH
• mapování chromozomů metody   MeSH
• molekulární evoluce MeSH
• multigenová rodina genetika   MeSH
• repetitivní sekvence nukleových kyselin genetika   MeSH
• telomery genetika   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• DNA MeSH

Spiders are an intriguing model to analyse sex chromosome evolution because of their peculiar multiple X chromosome systems. Y chromosomes were considered rare in this group, arising after neo-sex chromosome formation by X chromosome-autosome rearrangements. However, recent findings suggest that Y chromosomes are more common in spiders than previously thought. Besides neo-sex chromosomes, they are also involved in the ancient X1X2Y system of haplogyne spiders, whose origin is unknown. Furthermore, spiders seem to exhibit obligatorily one or two pairs of cryptic homomorphic XY chromosomes (further cryptic sex chromosome pairs, CSCPs), which could represent the ancestral spider sex chromosomes. Here, we analyse the molecular differentiation of particular types of spider Y chromosomes in a representative set of ten species by comparative genomic hybridisation (CGH). We found a high Y chromosome differentiation in haplogyne species with X1X2Y system except for Loxosceles spp. CSCP chromosomes exhibited generally low differentiation. Possible mechanisms and factors behind the observed patterns are discussed. The presence of autosomal regions marked predominantly or exclusively with the male or female probe was also recorded. We attribute this pattern to intraspecific variability in the copy number and distribution of certain repetitive DNAs in spider genomes, pointing thus to the limits of CGH in this arachnid group. In addition, we confirmed nonrandom association of chromosomes belonging to particular CSCPs at spermatogonial mitosis and spermatocyte meiosis and their association with multiple Xs throughout meiosis. Taken together, our data suggest diverse evolutionary pathways of molecular differentiation in different types of spider Y chromosomes.

• Klíčová slova
• Arthropoda, X1X20, X1X2Y, Y chromosome, achiasmatic pairing, in situ hybridisation, karyotype evolution, male-specific region, neo-sex chromosome, repetitive DNA,
• MeSH
• biologická evoluce * MeSH
• genom * MeSH
• karyotyp MeSH
• meióza * MeSH
• pavouci genetika   MeSH
• pohlavní chromozomy genetika   MeSH
• sexuální diferenciace * MeSH
• srovnávací genomová hybridizace metody   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The Erythrinidae family (Teleostei: Characiformes) is a small Neotropical fish group with a wide distribution throughout South America, where Hoplias malabaricus corresponds to the most widespread and cytogenetically studied taxon. This species possesses significant genetic variation, as well as huge karyotype diversity among populations, as reflected by its seven major karyotype forms (i.e., karyomorphs A-G) identified up to now. Although morphological differences in their bodies are not outstanding, H. malabaricus karyomorphs are easily identified by differences in 2n, morphology and size of chromosomes, as well as by distinct evolutionary steps of sex chromosomes development. Here, we performed comparative genomic hybridization (CGH) to analyse both the intra- and inter-genomic status in terms of repetitive DNA divergence among all but one (E) H. malabaricus karyomorphs. Our results indicated that they have close relationships, but with evolutionary divergences among their genomes, yielding a range of non-overlapping karyomorph-specific signals. Besides, male-specific regions were uncovered on the sex chromosomes, confirming their differential evolutionary trajectories. In conclusion, the hypothesis that H. malabaricus karyomorphs are result of speciation events was strengthened.

• Klíčová slova
• CGH, fish cytogenetics, intraspecific variability, multiple sex chromosomes, sex chromosome turnover, sex-determining region, speciation, species complex,
• Publikační typ
• časopisecké články MeSH

Abstract: Fishes exhibit the greatest diversity of species among vertebrates, offering a number of relevant models for genetic and evolutionary studies. The investigation of sex chromosome differentiation is a very active and striking research area of fish cytogenetics, as fishes represent one of the most vital model groups. Neotropical fish species show an amazing variety of sex chromosome systems, where different stages of differentiation can be found, ranging from homomorphic to highly differentiated sex chromosomes. Here, we draw attention on the impact of recent developments in molecular cytogenetic analyses that helped to elucidate many unknown questions about fish sex chromosome evolution, using excellent characiform models occurring in the Neotropical region, namely the Erythrinidae family and the Triportheus genus. While in Erythrinidae distinct XY and/or multiple XY-derived sex chromosome systems have independently evolved at least four different times, representatives of Triportheus show an opposite scenario, i.e., highly conserved ZZ/ZW system with a monophyletic origin. In both cases, recent molecular approaches, such as mapping of repetitive DNA classes, comparative genomic hybridization (CGH), and whole chromosome painting (WCP), allowed us to unmask several new features linked to the molecular composition and differentiation processes of sex chromosomes in fishes.

• Klíčová slova
• alternative evolutionary models, conventional and molecular cytogenetics, independent and common origins, simple and multiple sex chromosomes,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

In the article we summarize the most common recent cytogenetic methods used in analysis of karyotypes in Heteroptera. We seek to show the pros and cons of the spreading method compared with the traditional squashing method. We discuss the suitability of gonad, midgut and embryo tissue in Cimex lectularius Linnaeus, 1758 chromosome research and production of figures of whole mitosis and meiosis, using the spreading method. The hotplate spreading technique has many advantages in comparison with the squashing technique. Chromosomal slides prepared from the testes tissue gave the best results, tissues of eggs and midgut epithelium are not suitable. Metaphase II is the only division phase in which sex chromosomes can be clearly distinguished. Chromosome number determination is easy during metaphase I and metaphase II. Spreading of gonad tissue is a suitable method for the cytogenetic analysis of holokinetic chromosomes of Cimex lectularius.

• Klíčová slova
• holokinetic chromosomes, karyogram, midgut, spreading method, squashing method, testes,
• Publikační typ
• časopisecké články MeSH