Genome fractionation and loss of heterozygosity in hybrids and polyploids: Mechanisms, consequences for selection, and link to gene function

Hybridization and genome duplication have played crucial roles in the evolution of many animal and plant taxa. The subgenomes of parental species undergo considerable changes in hybrids and polyploids, which often selectively eliminate segments of one subgenome. However, the mechanisms underlying these changes are not well understood, particularly when the hybridization is linked with asexual reproduction that opens up unexpected evolutionary pathways. To elucidate this problem, we compared published cytogenetic and RNAseq data with exome sequences of asexual diploid and polyploid hybrids between three fish species; Cobitis elongatoides, C taenia, and C tanaitica. Clonal genomes remained generally static at chromosome-scale levels but their heterozygosity gradually deteriorated at the level of individual genes owing to allelic deletions and conversions. Interestingly, the impact of both processes varies among animals and genomic regions depending on ploidy level and the properties of affected genes. Namely, polyploids were more tolerant to deletions than diploid asexuals where conversions prevailed, and genomic restructuring events accumulated preferentially in genes characterized by high transcription levels and GC-content, strong purifying selection and specific functions like interacting with intracellular membranes. Although hybrids were phenotypically more similar to C taenia, we found that they preferentially retained C elongatoides alleles. This demonstrates that favored subgenome is not necessarily the transcriptionally dominant one. This study demonstrated that subgenomes in asexual hybrids and polyploids evolve under a complex interplay of selection and several molecular mechanisms whose efficiency depends on the organism's ploidy level, as well as functional properties and parental ancestry of the genomic region.Web of Science38125274525

Noninvasive spot analysis of miniatures with portable and laboratory instruments: a methodology for specific use in miniature painting research

The methodology brings a comprehensive procedure of non-invasive materials analysis of painted miniature artworks, while it is divided into two subsequent parts. In the first part, it describes the use of portable devices for spectroscopic analysis of miniatures, and in the second, it deals with the application of a new methodological procedure for phase/structural materials analysis based on X-ray powder diffraction. The methodology thus includes the following procedures: (i) determination of the elemental composition of the colour layer by the x-ray fluorescence analysis, (ii) identification of binders and other organic compounds using infrared spectroscopy (FT-IR), and finally (iii) phase/mineralogical and structural analysis to describe in more detail the pigments used and processes of their degradation. As part of this last step, the limits of Raman spectroscopy (RS) and the advantages of powder X-ray diffraction and micro-diffraction (XRPD and micro-XRPD) are described, which include greater gentleness to the analysed objects. A very complete and above all non-invasive methodological procedure for the analysis of miniatures is thus offered, which uses the complementarity of individual methods and which can be partly applied already in situ (directly in collection institutions) and partly at specialized workplaces

Bodová neinvazivní analýza miniatur přenosnými a laboratorními nástroji: metodika pro specifické použití ve výzkumu miniaturního malířství

The methodology brings a comprehensive procedure of non-invasive materials analysis of painted miniature artworks, while it is divided into two subsequent parts. In the first part, it describes the use of portable devices for spectroscopic analysis of miniatures, and in the second, it deals with the application of a new methodological procedure for phase/structural materials analysis based on X-ray powder diffraction. The methodology thus includes the following procedures: (i) determination of the elemental composition of the colour layer by the x-ray fluorescence analysis, (ii) identification of binders and other organic compounds using infrared spectroscopy (FT-IR), and finally (iii) phase/mineralogical and structural analysis to describe in more detail the pigments used and processes of their degradation. As part of this last step, the limits of Raman spectroscopy (RS) and the advantages of powder X-ray diffraction and micro-diffraction (XRPD and micro-XRPD) are described, which include greater gentleness to the analysed objects. A very complete and above all non-invasive methodological procedure for the analysis of miniatures is thus offered, which uses the complementarity of individual methods and which can be partly applied already in situ (directly in collection institutions) and partly at specialized workplaces