Molekulární cytogenetika paprskoploutvých ryb: od repetitivních sekvencí po analýzu celého genomu

Paprskoploutvé ryby, Actinopterygii, skupina s nejvyšší taxonomickou diverzitou mezi všemi obratlovci, představují v posledním období atraktivní objekt evolučních studií. S pokrokem v oblasti molekulární cytogenetiky a cytogenomiky roste i význam těchto metod ve studiu uspořádání a evoluce rybích genomů jako základu této diverzity. Má dizertační práce se zabývá studiem evoluce genomu vybraných skupin ryb, a to jak bazálních linií parskoploutvých (Lepisosteidae a Amiidae) a kostnatých (Pantodontidae), tak i "vyšších" kostnatých ryb z čeledí Cobitidae a Coregonidae. Využila jsem metody konvenční a molekulární cytogenetiky společně s fylogenetickými a statistickými přístupy. V rámci své dizertační práce popisuji cytogenetickou variabilitu blízce příbuzných druhů síhů (Coregonus), a roli repetitivních úseků genomu v ekologické speciaci. V kontrastu s recentní cytotaxonomickou diverzitou síhů, jsme odhalili relativně dlouhodobou karyotypovou stabilitu ve spojení s asexuálním rozmnožováním u sekavců rodu Cobitis. V další publikaci detailně popisujeme překvapivé uspořádání AT/GC bazí na chromozomech a v genomu kostlínů (Atractosteus a Lepisosteus) a bioinformaticky analyzujeme jejich uspořádání v genomu těchto bazálních paprskoploutvých ryb v kontextu hlavních linií obratlovců. V návaznosti na práci o...Actinopterygian fishes exhibit the greatest taxonomical diversity of all vertebrates, making this group attractive to address numerous evolutionary questions. The role of molecular cytogenetics and cytogenomics further increase because recent advances in these fields provide more comprehensive view of fish genome organization and evolutionary dynamics, responsible for this amazing diversity. My Thesis investigates the genome organization of selected fish lineages, namely basal lineages of Actinopterygians (Lepisosteidae and Amiidae) and Teleosts (Pantodontidae), together with "modern" fishes Cobitidae and Coregonidae. I have integrated conventional and molecular cytogenetic techniques together with phylogenetic and statistical approaches. Publications included into the Thesis describe e.g. the cytogenetic variability and dynamics in closely related fish species of the genus Coregonus and the impact of repetitive sequences on the ecological speciation. In contrast to the recent cytotaxonomical diversity of Coregonids, we have detected a karyotype stability associated with asexual reproduction in spined loaches of the genus Cobitis. In the subsequent publication, we describe a surprising AT/GC genome organization in gars (Atractosteus and Lepisosteus) and summarize the knowledge of genome...Department of ZoologyKatedra zoologieFaculty of SciencePřírodovědecká fakult

Present and Future Salmonid Cytogenetics

Salmonids are extremely important economically and scientifically; therefore, dynamic developments in their research have occurred and will continue occurring in the future. At the same time, their complex phylogeny and taxonomy are challenging for traditional approaches in research. Here, we first provide discoveries regarding the hitherto completely unknown cytogenetic characteristics of the Anatolian endemic flathead trout, Salmo platycephalus, and summarize the presently known, albeit highly complicated, situation in the genus Salmo. Secondly, by outlining future directions of salmonid cytogenomics, we have produced a prototypical virtual karyotype of Salmo trutta, the closest relative of S. platycephalus. This production is now possible thanks to the high-quality genome assembled to the chromosome level in S. trutta via soft-masking, including a direct labelling of repetitive sequences along the chromosome sequence. Repetitive sequences were crucial for traditional fish cytogenetics and hence should also be utilized in fish cytogenomics. As such virtual karyotypes become increasingly available in the very near future, it is necessary to integrate both present and future approaches to maximize their respective benefits. Finally, we show how the presumably repetitive sequences in salmonids can change the understanding of the overall relationship between genome size and G+C content, creating another outstanding question in salmonid cytogenomics waiting to be resolved

Out of Asia Minor into Danube Drainage: Phylogeography and colonisation pathways in the loach fish Cobitis strumicae

The spiny loach Cobitis strumicae is a small bottom-dwelling freshwater fish whose progenitor colonised the Balkan Peninsula from the Near East through the Asia Minor. The current geographic distribution of C. strumicae forms a ring around the Stara Planina (Balkan mountains), inhabitting Danube Basin and coastal rivers of Black Sea and Aegean Sea. Using one marker of mitochondrial DNA (gene for cytochrom b) and one marker of nuclear DNA (S7 gene, first intron), we reconstructed the species distribution and phylogenetic relationship of 44 populations throughout C. strumicae distribution. We also analysed its sister species, C. punctilineata, which lives inside the distribution area of C. strumicae. Aplication of four phylogenetic approaches confirm the monophyly and species statut and endemicity of C. punctilineata, and, moreover, the evidence of secondary hybridization with C. strumicae was found. The network analysis using median-joining method showed deep divergence between the both species. Phylogenetic analyses for cyt b gene confirmed the monophyly of C. strumicae, with internal substructure into at least two well divided lineages, which suggests the process of local speciation. Phylogenetic analyses of S7 gene did not support the monophyly of C. strumicae. Instead, the two separated..

Evidence of Interspecific Chromosomal Diversification in Rainbowfishes (Melanotaeniidae, Teleostei)

Rainbowfishes (Melanotaeniidae) are the largest monophyletic group of freshwater fishes occurring in Australia and New Guinea, with 112 species currently recognised. Despite their high taxonomic diversity, rainbowfishes remain poorly studied from a cytogenetic perspective. Using conventional (Giemsa staining, C banding, chromomycin A3 staining) and molecular (fluorescence in situ hybridisation with ribosomal DNA (rDNA) and telomeric probes) cytogenetic protocols, karyotypes and associated chromosomal characteristics of five species were examined. We covered all major lineages of this group, namely, Running River rainbowfish Melanotaenia sp., red rainbowfish Glossolepis incisus, threadfin rainbowfish Iriatherina werneri, ornate rainbowfish Rhadinocentrus ornatus, and Cairns rainbowfish Cairnsichthys rhombosomoides. All species had conserved diploid chromosome numbers 2n = 48, but karyotypes differed among species; while Melanotaenia sp., G. incisus, and I. werneri possessed karyotypes composed of exclusively subtelo/acrocentric chromosomes, the karyotype of R. ornatus displayed six pairs of submetacentric and 18 pairs of subtelo/acrocentric chromosomes, while C. rhombosomoides possessed a karyotype composed of four pairs of submetacentric and 20 pairs of subtelo/acrocentric chromosomes. No heteromorphic sex chromosomes were detected using conventional cytogenetic techniques. Our data indicate a conserved 2n in Melanotaeniidae, but morphologically variable karyotypes, rDNA sites, and heterochromatin distributions. Differences were observed especially in taxonomically divergent species, suggesting interspecies chromosome rearrangements

Molecular cytogenetics of selected actinopterygian fishes: insight from repetitive sequences to whole genome analyses

Actinopterygian fishes exhibit the greatest taxonomical diversity of all vertebrates, making this group attractive to address numerous evolutionary questions. The role of molecular cytogenetics and cytogenomics further increase because recent advances in these fields provide more comprehensive view of fish genome organization and evolutionary dynamics, responsible for this amazing diversity. My Thesis investigates the genome organization of selected fish lineages, namely basal lineages of Actinopterygians (Lepisosteidae and Amiidae) and Teleosts (Pantodontidae), together with "modern" fishes Cobitidae and Coregonidae. I have integrated conventional and molecular cytogenetic techniques together with phylogenetic and statistical approaches. Publications included into the Thesis describe e.g. the cytogenetic variability and dynamics in closely related fish species of the genus Coregonus and the impact of repetitive sequences on the ecological speciation. In contrast to the recent cytotaxonomical diversity of Coregonids, we have detected a karyotype stability associated with asexual reproduction in spined loaches of the genus Cobitis. In the subsequent publication, we describe a surprising AT/GC genome organization in gars (Atractosteus and Lepisosteus) and summarize the knowledge of genome..

MARKETING FINANCIJSKIH USLUGA U VREMENU DRUŠTVENIH MREŽA: SLUČAJ MARKETINGA OSIGURANJA

Online social network sites (OSNSs) pose a new trend in social communication that gains an enormous popularity in short time. Consequently, the chance for marketing of products and companies is opening. As well, the question about the possibility of using this channel also for the financial sector, including insurance companies, arises. This idea is followed up by the main goal of the paper: to explore Online Social Network Sites’ (OSNS) role in retail commercial insurance marketing and uncover consumers’ perceptions about the acceptability of insurance company communication and distribution into the environment of OSNSs. The paper contains theoretical analysis of the usability of OSNS as a communication and distribution channel for insurance companies. Besides the theoretical analysis, also the survey of consumers’ perception was conducted. Our results indicate that OSNSs represent a possible channel for insurance company marketing mainly in the area of the communication. However, the distribution of commercial insurance by OSNSs is also not an omissible area. These findings are widely applicable also for other financial services’ marketing.Društvene mreže (OSNS) predstavljaju novi trend u društvenoj komunikaciji, i u kratkom vremenu su stekle golemu popularnost. Stoga se otvara mogućnost za marketing proizvoda i tvrtki. Također se pojavljuje i pitanje mogućnosti korištenja ovog kanala u financijskom sektoru, uključujući osiguravateljne kuće. Ovu ideju slijedi glavni cilj rada: istražiti ulogu društvenih mreža u marketingu komercijanog osiguranja na malo i otkriti percepciju potrošača glede prihvatljivosti komunikacije i prisutnosti osiguravateljne kuće na društvenim mrežama. U ovom radu se teorijski analizira upotrebljivost društvenih mreža kao komunikacijskog i distribucijskog kanala za osiguravateljne kuće. Osim teorijske analize, provedeno je i istraživanje o percepciji potrošača. Naši rezultati pokazuju da su društvene mreže mogući kanal za marketing osiguravateljnih tvrtki uglavnom u području komunikacije. Ipak, mogućnost distribucije komercijalnog osiguranja društvenim mrežama nije zanemariva. Ovi rezultati su primjenljivi i na marketing drugih financijskih usluga

Cytogenetic Characterization of Seven Novel satDNA Markers in Two Species of Spined Loaches (Cobitis) and Their Clonal Hybrids

Interspecific hybridization is a powerful evolutionary force. However, the investigation of hybrids requires the application of methodologies that provide efficient and indubitable identification of both parental subgenomes in hybrid individuals. Repetitive DNA, and especially the satellite DNA sequences (satDNA), can rapidly diverge even between closely related species, hence providing a useful tool for cytogenetic investigations of hybrids. Recent progress in whole-genome sequencing (WGS) offers unprecedented possibilities for the development of new tools for species determination, including identification of species-specific satDNA markers. In this study, we focused on spined loaches (Cobitis, Teleostei), a group of fishes with frequent interspecific hybridization. Using the WGS of one species, C. elongatoides, we identified seven satDNA markers, which were mapped by fluorescence in situ hybridization on mitotic and lampbrush chromosomes of C. elongatoides, C. taenia and their triploid hybrids (C. elongatoides × 2C. taenia). Two of these markers were chromosome-specific in both species, one had centromeric localization in multiple chromosomes and four had variable patterns between tested species. Our study provided a novel set of cytogenetic markers for Cobitis species and demonstrated that NGS-based development of satDNA cytogenetic markers may provide a very efficient and easy tool for the investigation of hybrid genomes, cell ploidy, and karyotype evolution

Karyotype of Sabanejewia bulgarica (Drensky, 1928) (Teleostei, Cobitidae) from the Danube Delta, Romania

The karyotype of the freshwater fish Sabanejewia bulgarica (Drensky, 1928), from the Danube Delta, was studied by conventional Giemsa staining and the C-banding technique. The diploid chromosome number was 2n = 50. The karyotype contained 2 pairs of metacentric (the first one was much larger than the second one), 6 pairs of submetacentric and 17 pairs of subtelocentric to acrocentric chromosomes. Pericentromeric blocks of heterochromatin were revealed in most of the chromosome pairs. The karyotype phenotype of S. bulgarica was the same as found for S. balcanica from Northern Carpathian Mountains