Biology subjects

Janousek, B.

Publications and source records attributed to Janousek, B..

4 recordsLinked to original sources

bioRxiv2025

Sex chromosome pairing and multivalent associations during meiosis in diploid and polyploid Silene latifolia

Sex chromosomes undergo various modifications that affect their synapsis during meiosis. While most of the genome achieves full synapsis by the end of pachytene, the non-recombining regions of XY (or ZW) chromosomes often remain asynaptic, and fail to form physical associations at metaphase I. Despite significant progress in animal models, the meiotic behaviour dynamics of plant sex chromosomes remain largely unexplored. In this study, we employed super-resolution microscopy to analyse 3D chromosome organization and the localization of key meiotic proteins. Namely, we studied the dynamics of ASY1, ZYP1, and HEI10, across the leptotene to pachytene stages, and compared sex chromosome behaviour in dioecious Silene latifolia with related gynodioecious S. vulgaris. Our findings show that both exhibits a class I crossover (CO) frequency comparable to mammals, indicating moderate COs per bivalent and their similar genetic determinants. We document variation in sex chromosome configurations, from rod bivalents in diploids to open-ring tetravalents in autopolyploids, and characterize Y chromosome behaviour across XXY, XXXY, and XXYY karyotypes. These results reveal pronounced variation in pairing and synaptic patterns, even within a shared genetic background. We discuss how these patterns reflect the evolutionary trajectory of the non-recombining region and provide the most detailed cytogenetic analysis of sex chromosome pairing in a plant with evolutionary young sex chromosomes.

cell biology↗

bioRxiv2025

Contrasting patterns of subtelomeric satellite superfamily in the Cannabaceae family

Satellite DNA (satDNA) is a rapidly evolving component of plant genomes, often found in centromeric, telomeric, and heterochromatic regions. Due to their variability and species- or population-specific distribution, satDNA serves as valuable cytogenetic markers for studying chromosomal rearrangements and karyotype evolution in closely related species. In dioecious species Cannabis sativa, Humulus lupulus, and Humulus japonicus, previous studies have identified species-specific subtelomeric repeats CS-1, HSR1, and HJSR. While these satellites have been used to differentiate sex chromosomes from autosomes, their evolutionary origins, sequence variation and pattern of conservation among related species remain largely unexplored. In this study, we combine bioinformatics analysis with molecular cloning to analyze sequence similarity among these shared satellites and determine their inter-specific chromosomal localization using fluorescence in situ hybridization (FISH). Our results reveal that HSR1 and HJSR satellites are shared among all studied species suggested oaring from a common ancestor. In contrast, CS-1 satellite exhibit higher sequence divergence. Although all satellites are predominantly localized in subtelomeric regions, CS-1 in H. lupulus and HSR in C. sativa are localized in pericentromeric regions. These findings provide new insight into the evolutionary dynamics of satDNA in Cannabaceae family and its role in genome organization.

plant biology↗

bioRxiv2021

Adaptation of the autosomal part of the genome on the presence of dioecy

We have attempted to answer the question of whether the presence of sex chromosomes in the genome can affect the evolution of the autosomal part of the genome. As a model, we used dioecious plants from the section Otites of the genus Silene. We have observed a rise in adaptive evolution in the autosomal and pseudoautosomal parts of the genome, which are associated with the evolution of dioecy. This rise is caused neither by the accumulation of sexually antagonistic genes in the pseudoautosomal region nor by the co-evolution of genes acting in mitochondria (in spite of the fact that the dioecy evolved in this case most likely from cytoplasmic male sterility). Thus, this rise in the amount of positively selected codons is most likely caused by the adaptive evolution of genes involved in the specialization of the autosomal part of the genome on the dioecy as described in sex-allocation theory.

evolutionary biology↗

bioRxiv2018

Evolution of sex determination and heterogamety changes in section Otites of the genus Silene

Switches in heterogamety occasionally occur both in animals and plants, although plant sex determination systems are mostly more recently evolved than those of animals, and have had less time for switches to occur. However, our previous research revealed a switch in heterogamety in section Otites of the plant genus Silene.\n\nHere we analyse in detail the evolution of genetic sex determination in section Otites, which is estimated to have evolved about 0.55 MYA. Our study confirms female heterogamety in S. otites and newly reveals female heterogamety in S. borysthenica. Sequence analyses and genetic mapping show that the sex-linked regions of these two species are the same, but the region in S. colpophylla, a close relative with male heterogamety, is different. The sex chromosome pairs of S. colpophylla and S. otites each correspond to an autosome of the other species, and both differ from the XY pair in S. latifolia, in a different section of the genus. Our phylogenetic analysis suggests a possible change from female to male heterogamety within Silene section Otites, making these species suitable for detailed studies of the events involved.

evolutionary biology↗