DNA | Special Issue : Selected Papers from the Joint Meeting of the 23rd International Chromosome Conference (ICC) and the 24th International Colloquium in Animal Cytogenetics and Genomics (ICACG)

The Y or W sex chromosome of a heteromorphic pair is usually heterochromatinised and degenerated. However, whether chromosome degeneration constantly proceeds toward an extreme end is not fully understood. Here, we present a case of intermittent evolution of W chromosomes caused by interpopulation [...] Read more.

The Y or W sex chromosome of a heteromorphic pair is usually heterochromatinised and degenerated. However, whether chromosome degeneration constantly proceeds toward an extreme end is not fully understood. Here, we present a case of intermittent evolution of W chromosomes caused by interpopulation hybridisation in the Japanese soil-frog, Glandirana rugosa. This species includes two heteromorphic sex chromosome systems, which are separated into geographic populations, namely the XY and ZW groups. In this study, to uncover the evolutionary mechanisms of the heterogeneous W chromosomes, we genetically investigated the geographic differentiation of the ZW populations along with the closely located XY populations. Analysis of mitochondrial cytochrome b sequences detected three distinct clades, named ZW1, ZW2, and ZW3. High throughput analyses of nuclear genomic DNA showed that autosomal alleles of XY populations were deeply introgressed into the ZW3 sub-group. Based on the genotypes of sex-linked single nucleotide polymorphisms, W-borne androgen receptor gene expression, and WW developmental mortality, we concluded that the X chromosomes were recycled to W chromosomes. Upon inclusion of two cases from another group, Neo-ZW, we observed that the X chromosomes were recycled independently at least four times to the new W chromosomes: a repetition of degeneration and resurrection. Full article

(This article belongs to the Special Issue Selected Papers from the Joint Meeting of the 23rd International Chromosome Conference (ICC) and the 24th International Colloquium in Animal Cytogenetics and Genomics (ICACG))

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18 pages, 4792 KiB

Open AccessEditor’s ChoiceArticle

The Nature and Chromosomal Landscape of Endogenous Retroviruses (ERVs) Integrated in the Sheep Nuclear Genome

by Sarbast Ihsan Mustafa, Trude Schwarzacher and John S. Heslop-Harrison

DNA 2022, 2(1), 86-103; https://doi.org/10.3390/dna2010007 - 16 Mar 2022

Cited by 2 | Viewed by 3366

Abstract

Endogenous retroviruses (ERVs) represent genomic components of retroviral origin that are found integrated in the genomes of various species of vertebrates. These genomic elements have been widely characterized in model organisms and humans. However, composition and abundances of ERVs have not been categorized [...] Read more.

Endogenous retroviruses (ERVs) represent genomic components of retroviral origin that are found integrated in the genomes of various species of vertebrates. These genomic elements have been widely characterized in model organisms and humans. However, composition and abundances of ERVs have not been categorized fully in all domestic animals. The advent of next generation sequencing technologies, development of bioinformatics tools, availability of genomic databases, and molecular cytogenetic techniques have revolutionized the exploration of the genome structure. Here, we investigated the nature, abundance, organization and assembly of ERVs and complete genomes of Jaagsiekte sheep retrovirus (JSRV) from high-throughput sequencing (HTS) data from two Iraqi domestic sheep breeds. We used graph-based read clustering (RepeatExplorer), frequency analysis of short motifs (k-mers), alignment to reference genome assemblies and fluorescent in situ hybridization (FISH). Three classes of ERVs were identified with the total genomic proportions of 0.55% from all analyzed whole genome sequencing raw reads, while FISH to ovine metaphase chromosomes exhibited abundant centromeric to dispersed distribution of these ERVs. Furthermore, the complete genomes of JSRV of two Iraqi sheep breeds were assembled and phylogenetically clustered with the known enJSRV proviruses in sheep worldwide. Characterization of partial and complete sequences of mammalian ERVs is valuable in providing insights into the genome landscape, to help with future genome assemblies, and to identify potential sources of disease when ERVs become active. Full article

(This article belongs to the Special Issue Selected Papers from the Joint Meeting of the 23rd International Chromosome Conference (ICC) and the 24th International Colloquium in Animal Cytogenetics and Genomics (ICACG))

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7 pages, 1063 KiB

Open AccessArticle

Karyotype Organization of the Endangered Species Yellow Cardinal (Gubernatrix cristata)

by Sandra Eloisa Bülau, Rafael Kretschmer, Ivanete de Oliveira Furo, Edivaldo Herculano Correa de Oliveira and Thales Renato Ochotorena de Freitas

DNA 2021, 1(2), 77-83; https://doi.org/10.3390/dna1020008 - 27 Oct 2021

Cited by 3 | Viewed by 3552

Abstract

Karyotypic analyses have several applications in studies of chromosome organization, evolution, and cytotaxonomy. They are also essential to genome assembly projects. Here, we present for the first time the karyotype description of the endangered species yellow cardinal, Gubernatrix cristata (Passeriformes, Thraupidae), using conventional [...] Read more.

Karyotypic analyses have several applications in studies of chromosome organization, evolution, and cytotaxonomy. They are also essential to genome assembly projects. Here, we present for the first time the karyotype description of the endangered species yellow cardinal, Gubernatrix cristata (Passeriformes, Thraupidae), using conventional staining with Giemsa and 18S rDNA probes. This species has 78 chromosomes, with 12 pairs of macrochromosomes and 27 microchromosome pairs. The 18S rDNA clusters were found in four microchromosomes. Our results revealed that G. cristata has a typical avian karyotype (approximately 80 chromosomes). However, G. cristata has an apomorphic state in relation to the 18S rDNA distribution since the ancestral condition corresponds to only two microchromosomes with these sequences. Probably, duplications and translocations were responsible for increasing the number of 18S rDNA clusters in G. cristata. The results were compared and discussed with respect to other Thraupidae and Passeriformes members. Considering the globally threatened status of G. cristata, we believe that its karyotype description could be a starting point for future cytogenetics and sequencing projects. Full article

(This article belongs to the Special Issue Selected Papers from the Joint Meeting of the 23rd International Chromosome Conference (ICC) and the 24th International Colloquium in Animal Cytogenetics and Genomics (ICACG))

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9 pages, 540 KiB

Open AccessEditor’s ChoiceArticle

Incidence, Reproductive Outcome, and Economic Impact of Reciprocal Translocations in the Domestic Pig

by Nicole M. Lewis, Claudia C. Rathje, Carla Canedo-Ribeiro, Lisa M. Bosman, Lucas G. Kiazim, Rebecca L. Jennings, Rebecca E. O’Connor, Giuseppe Silvestri and Darren K. Griffin

DNA 2021, 1(2), 68-76; https://doi.org/10.3390/dna1020007 - 9 Oct 2021

Cited by 2 | Viewed by 3664

Abstract

Pigs (Sus scrofa) have vast economic importance, with pork accounting for over 30% of the global meat consumption. Chromosomal abnormalities, and in particular reciprocal translocations (RTs), are an important cause of hypoprolificacy (litter size reduction) in pigs. However, these do not [...] Read more.

Pigs (Sus scrofa) have vast economic importance, with pork accounting for over 30% of the global meat consumption. Chromosomal abnormalities, and in particular reciprocal translocations (RTs), are an important cause of hypoprolificacy (litter size reduction) in pigs. However, these do not necessarily present with a recognizable phenotype and may cause significant economic losses for breeders when undetected. Here, we present a reappraisal of the incidence of RTs across several European pig herds, using contemporary methodology, as well as an analysis modelling the economic impact of these abnormalities. Molecular cytogenetic investigation was completed by karyotyping and/or multiprobe FISH (fluorescence in situ hybridisation) between 2016–2021, testing 2673 animals. We identified 19 types of chromosome abnormalities, the prevalence of these errors in the database was 9.1%, and the estimated incidence of de novo errors was 0.90%. Financial modelling across different scenarios revealed the potential economic impact of an undetected RT, ranging from £69,802 for an individual affected terminal boar in a commercial farm selling weaned pigs, to £51,215,378 for a genetics company with an undetected RT in a dam line boar used in a nucleus farm. Moreover, the added benefits of screening by FISH instead of karyotyping were estimated, providing a strong case for proactive screening by this approach. Full article

(This article belongs to the Special Issue Selected Papers from the Joint Meeting of the 23rd International Chromosome Conference (ICC) and the 24th International Colloquium in Animal Cytogenetics and Genomics (ICACG))

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14 pages, 4283 KiB

Open AccessReview

3D Ultrastructural Imaging of Chromosomes Using Serial Block-Face Scanning Electron Microscopy (SBFSEM)

by Mohammed Yusuf, Atiqa Sajid, Ian K. Robinson and El-Nasir Lalani

DNA 2022, 2(1), 30-43; https://doi.org/10.3390/dna2010003 - 5 Feb 2022

Cited by 4 | Viewed by 4319

Abstract

To date, our understanding of how DNA is packaged in the cell nucleus, condensed from chromatin into chromosomes, and organized throughout the cell cycle remains sparse. Three dimensional (3D) ultrastructural imaging is an important tool for unravelling the organizational structure of chromosomes. For [...] Read more.

To date, our understanding of how DNA is packaged in the cell nucleus, condensed from chromatin into chromosomes, and organized throughout the cell cycle remains sparse. Three dimensional (3D) ultrastructural imaging is an important tool for unravelling the organizational structure of chromosomes. For large volume 3D imaging of biological samples, serial block-face scanning electron microscopy (SBFSEM) has been applied, whereby ultrastructural information is achieved by analyzing 3D reconstructions acquired from measured data sets. In this review, we summarize the contribution of SBFSEM for obtaining 3D images of chromosomes to investigate their ultrastructure and organization in the cell and its nucleus. Furthermore, this review highlights the potential of SBFSEM for advancing 3D chromosome research. Full article

(This article belongs to the Special Issue Selected Papers from the Joint Meeting of the 23rd International Chromosome Conference (ICC) and the 24th International Colloquium in Animal Cytogenetics and Genomics (ICACG))

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8 pages, 1383 KiB

Open AccessBrief Report

Direct Chromosome Preparation Method in Avian Embryos for Cytogenetic Studies: Quick, Easy and Cheap

by Suziane Alves Barcellos, Marcelo Santos de Souza, Victoria Tura, Larissa Rodrigues Pereira, Rafael Kretschmer, Ricardo José Gunski and Analía Del Valle Garnero

DNA 2022, 2(1), 22-29; https://doi.org/10.3390/dna2010002 - 26 Jan 2022

Cited by 4 | Viewed by 6041

Abstract

Avian cell culture is widely applied for cytogenetic studies, the improvement of which increasingly allows for the production of high-quality chromosomes, essential to perform both classical and molecular cytogenetic studies. Among these approaches, there are two main types: fibroblast and bone marrow culture. [...] Read more.

Avian cell culture is widely applied for cytogenetic studies, the improvement of which increasingly allows for the production of high-quality chromosomes, essential to perform both classical and molecular cytogenetic studies. Among these approaches, there are two main types: fibroblast and bone marrow culture. Despite its high cost and complexity, fibroblast culture is considered the superior approach due to the quality of the metaphases produced. Short-term bone marrow cultivation provides more condensed chromosomes but nonetheless is quicker and easier. In the search for a quicker, cheaper way to prepare metaphases without losing quality, the present work developed a novel, widely applicable protocol for avian chromosome preparation. Twenty-one bird embryos from distinct families were sampled: Icteridae, Columbidae, Furnariidae, Estrildidae, Thraupidae, Troglodytidae and Ardeidae. The protocol was based on a combination of modified fibroblast culture and bone marrow cultivation, taking the advantages of both. The results show that all species consistently presented good mitotic indexes and high-quality chromosomes. Overall, the application of this protocol for bird cytogenetics can optimize the time, considering that most fibroblast cultures take at least 3 days and often much longer. However, our protocol can be performed in 3 h with a much-reduced cost of reagents and equipment. Full article

(This article belongs to the Special Issue Selected Papers from the Joint Meeting of the 23rd International Chromosome Conference (ICC) and the 24th International Colloquium in Animal Cytogenetics and Genomics (ICACG))

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7 pages, 1933 KiB

Open AccessCommentary

Classification Problems of Repetitive DNA Sequences

by Eva Šatović-Vukšić and Miroslav Plohl

DNA 2021, 1(2), 84-90; https://doi.org/10.3390/dna1020009 - 2 Nov 2021

Cited by 3 | Viewed by 4009

Abstract

Repetitive DNA sequences, satellite DNAs (satDNAs) and transposable elements (TEs) are essential components of the genome landscape, with many different roles in genome function and evolution. Despite significant advances in sequencing technologies and bioinformatics tools, detection and classification of repetitive sequences can still [...] Read more.

Repetitive DNA sequences, satellite DNAs (satDNAs) and transposable elements (TEs) are essential components of the genome landscape, with many different roles in genome function and evolution. Despite significant advances in sequencing technologies and bioinformatics tools, detection and classification of repetitive sequences can still be an obstacle to the analysis of genomic repeats. Here, we summarize how specificities in repetitive DNA organizational patterns can lead to an inability to classify (and study) a significant fraction of bivalve mollusk repetitive sequences. We suggest that the main reasons for this inability are: the predominant association of satDNA arrays with Helitron/Helentron TEs; the existence of many complex loci; and the unusual, highly scattered organization of short satDNA arrays or single monomers across the whole genome. The specificities of bivalve genomes confirm the need for introducing diverse organisms as models in order to understand all aspects of repetitive DNA biology. It is expected that further development of sequencing techniques and synergy among different bioinformatics tools and databases will enable quick and unambiguous characterization and classification of repetitive DNA sequences in assembled genomes. Full article

(This article belongs to the Special Issue Selected Papers from the Joint Meeting of the 23rd International Chromosome Conference (ICC) and the 24th International Colloquium in Animal Cytogenetics and Genomics (ICACG))

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Selected Papers from the Joint Meeting of the 23rd International Chromosome Conference (ICC) and the 24th International Colloquium in Animal Cytogenetics and Genomics (ICACG)

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