Cervids are characterized by their greatest karyotypic diversity among mammals. A great diversity of chromosome numbers in notably similar morphological groups leads to the existence of several complexes of cryptic species and taxonomic uncertainties. Some deer lineages, such as those of Neotropical deer, stand out for a rapid chromosomal reorganization and intraspecific chromosome polymorphisms, which have not been properly explored yet. For that reason, we contribute to the study of deer karyotype diversity and taxonomy by producing and characterizing new molecular cytogenetic markers for the gray brocket deer (Subulo gouazoubira), a deer species that retained the hypothetical ancestral karyotype of Cervidae. We used bacterial artificial chromosome (BAC) clones derived from the cattle genome (Bos taurus) as markers, which were hybridized on S. gouazoubira metaphase chromosomes. In total, we mapped 108 markers, encompassing all gray brocket deer chromosomes, except the Y chromosome. The detailed analysis of fluorescent in situ hybridization results showed 6 fissions and 1 fusion as interchromosomal rearrangements that have separated cattle and gray brocket deer karyotypes. Each group of BAC probes derived from bovine chromosome pairs 1, 2, 5, 6, 8, and 9 showed hybridization signals on 2 different chromosomes, while pairs 28 and 26 are fused in tandem in a single acrocentric chromosome in S. gouazoubira. Furthermore, the BAC markers detected the occurrence of intrachromosomal rearrangements in the S. gouazoubira chromosomes homologous to pair 1 and the X chromosome of cattle. We present a karyotypic map of the 108 new markers, which will be of great importance for future karyotypic evolution studies in cervids and, consequently, help in their conservation and taxonomy resolution.
Telomere biology is closely linked to the process of aging. The restoration of telomere length by maintaining telome-rase activity in certain cell types of human adults allows for the proliferative capacity of the cells and preserves the regeneration potential of the tissue. The absence of telome-rase, that leads to telomere attrition and irreversible cell cycle arrest in most somatic cells, acts as a protective mechanism against uncontrolled cancer growth. Nevertheless, there have been numerous studies indicating noncanonical functions of telomerase besides those involved in telomere lengthening. Eusocial insects serve as a great system for aging research. This is because eusocial reproductives, such as queens and kings, have a significantly extended lifespan compared to nonreproductive individuals of the same species. We report that the somatic tissues of honeybee queens (Apis mellifera) are associated with upregulated telomerase activity; however, this upregulation does not fully correlate with the rate of DNA replication in the tissues. This indicates a noncanonical role of telomerase in the somatic tissues of honeybee queens.
The prenatal finding of a small supernumerary marker chromosome (sSMC) is a challenge for genetic counseling. Our analytic algorithm is based on sSMC frequencies and multicolor FISH to accelerate the procedure. The chromosomal origin, size, and degree of mosaicism of the sSMC then determine the prognosis. We illustrate the effectiveness on 4 prenatally identified de novo mosaic sSMCs derived from chromosomes 13/21, X, 3, and 17. Three sSMC carriers had a good prognosis and apparently healthy children were born, showing no abnormality till the last examination at the age of 4 years. One case had a poor prognosis, and the parents decided to terminate the pregnancy. Our work contributes to the laboratory and clinical management of prenatally detected sSMCs. FISH is a reliable method for fast sSMC evaluation and prognosis assessment; it prevents unnecessary delays and uncertainty, allows informed decision making, and reduces unnecessary pregnancy terminations.
- MeSH
- algoritmy MeSH
- chromozomální aberace * MeSH
- dospělí MeSH
- genetické asociační studie MeSH
- genetické poradenství MeSH
- heterozygot * MeSH
- hybridizace in situ fluorescenční MeSH
- karyotypizace MeSH
- kojenec MeSH
- lidé MeSH
- předškolní dítě MeSH
- prenatální diagnóza * MeSH
- prognóza MeSH
- těhotenství MeSH
- věk matky MeSH
- Check Tag
- dospělí MeSH
- kojenec MeSH
- lidé MeSH
- mužské pohlaví MeSH
- předškolní dítě MeSH
- těhotenství MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- kazuistiky MeSH
Recently, the reticulated giraffe (G. reticulata) was identified as a distinct species, which emphasized the need for intensive research in this interesting animal. To shed light on the meiotic process as a source of biodiversity, we analysed the frequency and distribution of meiotic recombination in 2 reticulated giraffe males. We used immunofluorescence detection of synaptonemal complex protein (SYCP3), meiotic double strand breaks (DSB, marked as RAD51 foci) in leptonema, and crossovers (COs, as MLH1 foci) in pachynema. The mean number of autosomal MLH1 foci per cell (27), which resulted from a single, distally located MLH1 focus observed on most chromosome arms, is one of the lowest among mammalian species analysed so far. The CO/DSB conversion ratio was 0.32. The pseudoautosomal region was localised in the Xq and Yp termini by FISH and showed an MLH1 focus in 83% of the pachytene cells. Chromatin structures corresponding to the nucleolus organiser regions were observed in the pachytene spermatocytes. The results are discussed in the context of known data on meiosis in Cetartiodactyla, depicting that the variation in CO frequency among species of this taxonomic group is mostly associated with their diploid chromosome number.
- MeSH
- fluorescenční protilátková technika MeSH
- hybridizace in situ fluorescenční MeSH
- meióza genetika MeSH
- MutL homolog 1 genetika MeSH
- organizátor jadérka genetika MeSH
- rekombinace genetická * MeSH
- rekombinasa Rad51 genetika MeSH
- synaptonemální komplex genetika MeSH
- žirafy genetika MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
The sibling species Microtus thomasi and M. atticus represent probably the highest karyotypic diversity within the genus Microtus and are an interesting model for chromosomal evolution studies. In addition to variation in autosomes, they show a high intraspecific variation in the size and morphology of both sex chromosomes. We analyzed individuals with different sex chromosome constitutions using 3 painting probes, 2 from Y chromosome variants and 1 from the small arm of the submetacentric X chromosome. Our comparative painting approach uncovered 12 variants of Y and 14 variants of X chromosomes, which demonstrates that the polymorphism of sex chromosomes is substantially larger than previously reported. We suggest that 2 main processes are responsible for this sex chromosome polymorphism: change of morphology from acrocentric to submetacentric or metacentric chromosomes and increase in size due to accumulation of repetitive DNA sequences, generating heterochromatic blocks. Strong genetic drift in small and fragmented populations of these 2 species could be related to the origin and maintenance of the large polymorphism of sex chromosomes. We proposed that a similar polymorphism variation combined with random drift fixing the biggest sex chromosomes could have occurred in the origin of some of the actual Microtus species with giant sex chromosomes.
- MeSH
- Arvicolinae genetika MeSH
- biologická evoluce MeSH
- chromozom X genetika MeSH
- chromozom Y genetika MeSH
- druhová specificita MeSH
- genová přestavba genetika MeSH
- heterochromatin genetika MeSH
- karyotypizace metody MeSH
- polymorfismus genetický genetika MeSH
- pruhování chromozomů metody MeSH
- repetitivní sekvence nukleových kyselin genetika MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
FISH is a useful method to identify individual chromosomes in a karyotype and to discover their structural changes accompanying genome evolution and speciation. DNA probes for FISH should be chromosome specific and/or exhibit specific patterns of distribution along each chromosome. Such probes are not available in many plants including meadow fescue (Festuca pratensis Huds.), an important forage grass species. In the present study, various DNA repeats identified in Illumina shotgun sequences specific to chromosome 4F of F. pratensis were used as probes for FISH to develop the molecular karyotype of meadow fescue and to reveal a long-range molecular organization of its chromosomes. Five tandem repeats produced specific patterns on individual chromosomes. Their use in combination with probes for rRNA genes enabled the establishment of the molecular karyotype of meadow fescue. Most of the mobile genetic elements were dispersed along all the chromosomes except for the DNA transposon CACTA, which was localized preferentially to telomeric and subtelomeric regions, and a putative LTR element, which was localized to (peri)centromeric regions. Cytogenetic mapping of the 5 tandem repeats in other accessions of meadow fescue showed a highly similar distribution and confirmed the versatility and robustness of these probes.
Festulolium are hybrids between fescue (Festuca) and ryegrass (Lolium) species and combine high seed yield of ryegrasses with abiotic stress tolerance of fescues. Chromosomes of Festuca and Lolium present in Festulolium freely pair and recombine, which results in highly variable progeny where every single plant has a unique chromosome constitution. Thus, the stability of the genomic composition in Festulolium cultivars is an important issue. In this work, we used in situ hybridization to examine the genomic composition (understood as the proportion of parental genomes present) over 3 consecutive generations of propagation via outcrossing (the first one being the generation used for cultivar registration) of 3 Festulolium cultivars. Our analysis revealed that the genome composition largely differs among the plants from individual cultivars but appears to be relatively stable over the generations. A gradual shift in the genome composition towards Lolium observed in the early generations of hybrids appears to reach a plateau where the proportions of parental genomes become stabilized. Nevertheless, the proportion remains unbalanced to a certain extent (always in favor of the Lolium genome) in each cultivar. Our observations indicate a possibility to modulate genomic composition in hybrids by breeders' selection without a compromise on stability.
Chromosome segregation in mammalian oocytes is prone to errors causing aneuploidy with consequences such as precocious termination of development or severe developmental disorders. Aneuploidy also represents a serious problem in procedures utilizing mammalian gametes and early embryos in vitro. In our study, we focused on congression defects during meiosis I and observed whole nondisjoined bivalents in meiosis II as a direct consequence, together with a substantially delayed first polar body extrusion. We also show that the congression defects are accompanied by less stable attachments of the kinetochores. Our results describe a process by which congression defects directly contribute to aneuploidy.
- MeSH
- aneuploidie * MeSH
- časosběrné zobrazování metody MeSH
- kinetochory metabolismus MeSH
- konfokální mikroskopie MeSH
- meióza genetika MeSH
- mikrotubuly metabolismus MeSH
- myši inbrední C57BL MeSH
- myši MeSH
- nondisjunkce genetická * MeSH
- oocyty metabolismus MeSH
- segregace chromozomů genetika MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- myši MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Bovine embryos are now routinely used in agricultural systems as a means of disseminating superior genetics worldwide, ultimately with the aim of feeding an ever-growing population. Further investigations, common for human IVF embryos, thus have priority to improve cattle IVF, as has screening for aneuploidy (abnormal chromosome number). Although the incidence and consequences of aneuploidy are well documented in human preimplantation embryos, they are less well known for the embryos of other animals. To address this, we assessed aneuploidy levels in thirty-one 2-cell bovine embryos derived from early- and late-cleaving zygotes. Contemporary approaches ( Whole Genome Amplification and next-generation sequencing) allowed aneuploidy assessment for all chromosomes in oocytes from donors aged 4-7 years. We also quantified mitochondrial DNA (mtDNA) levels in all blastomeres assessed, thereby testing the hypothesis that they are related to levels of aneuploidy. The overall incidence of aneuploidy in this cohort of bovine embryos was 41.1% and correlated significantly with the timing of cleavage (77.8% in late-cleaving vs. 31.8% in early-cleaving embryos). Moreover, based on mtDNA sequence read counts, we observed that the median mtDNA quantity is significantly lower in late-cleaving embryos. These findings further reinforce the use of the bovine system as a model for human IVF studies.
- MeSH
- aneuploidie * MeSH
- blastomery metabolismus MeSH
- buněčné dělení * MeSH
- časové faktory MeSH
- cytokineze MeSH
- embryo savčí cytologie embryologie metabolismus patologie MeSH
- fertilizace in vitro metody veterinární MeSH
- mitochondriální DNA analýza MeSH
- sekvenční analýza DNA metody veterinární MeSH
- skot MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- skot MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Geckos in general show extensive variability in sex determining systems, but only male heterogamety has been demonstrated in the members of their legless family Pygopodidae. In the pioneering study published more than 45 years ago, multiple sex chromosomes of the type X1X1X2X2/X1X2Y were described in Burton's legless lizard (Lialisburtonis) based on conventional cytogenetic techniques. We conducted cytogenetic analyses including comparative genomic hybridization and fluorescence in situ hybridization (FISH) with selected cytogenetic markers in this species and the previously cytogenetically unstudied Papua snake lizard (Lialis jicari) to better understand the nature of these sex chromosomes and their differentiation. Both species possess male heterogamety with an X1X1X2X2/X1X2Y sex chromosome system; however, the Y and one of the X chromosomes are not small chromosomes as previously reported in L. burtonis, but the largest macrochromosomal pair in the karyotype. The Y chromosomes in both species have large heterochromatic blocks with extensive accumulations of GATA and AC microsatellite motifs. FISH with telomeric probe revealed an exclusively terminal position of telomeric sequences in L. jicari (2n = 42 chromosomes in females), but extensive interstitial signals, potentially remnants of chromosomal fusions, in L.burtonis (2n = 34 in females). Our study shows that even largely differentiated and heteromorphic sex chromosomes might be misidentified by conventional cytogenetic analyses and that the application of more sensitive cytogenetic techniques for the identification of sex chromosomes is beneficial even in the classical examples of multiple sex chromosomes.
- MeSH
- hybridizace in situ fluorescenční MeSH
- karyotyp MeSH
- mikrosatelitní repetice genetika MeSH
- plazi genetika MeSH
- pohlavní chromozomy genetika MeSH
- srovnávací genomová hybridizace MeSH
- telomery genetika MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
