Sex chromatin is a conspicuous body that occurs in polyploid nuclei of most lepidopteran females and consists of numerous copies of the W sex chromosome. It is also a cytogenetic tool used to rapidly assess the W chromosome presence in Lepidoptera. However, certain chromosomal features could disrupt the formation of sex chromatin and lead to the false conclusion that the W chromosome is absent in the respective species. Here we tested the sex chromatin presence in 50 species of Geometridae. In eight selected species with either missing, atypical, or normal sex chromatin patterns, we performed a detailed karyotype analysis by means of comparative genomic hybridization (CGH) and fluorescence in situ hybridization (FISH). The results showed a high diversity of W chromosomes and clarified the reasons for atypical sex chromatin, including the absence or poor differentiation of W, rearrangements leading to the neo-W emergence, possible association with the nucleolus, and the existence of multiple W chromosomes. In two species, we detected intraspecific variability in the sex chromatin status and sex chromosome constitution. We show that the sex chromatin is not a sufficient marker of the W chromosome presence, but it may be an excellent tool to pinpoint species with atypical sex chromosomes.
- MeSH
- Species Specificity MeSH
- In Situ Hybridization, Fluorescence MeSH
- Karyotype MeSH
- Moths genetics MeSH
- Sex Chromosomes genetics MeSH
- Sex Chromatin metabolism MeSH
- Comparative Genomic Hybridization MeSH
- Animals MeSH
- Check Tag
- Male MeSH
- Female MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Genome size and chromosome number of five Cimicidae species were compared with the similar data recently received from Cimex lectularius parasitizing human. The average nuclear DNA content (males) was 2C = 1.47 pg in C. hemipterus, 2C = 1.61 pg in C. hirundinis, 2C = 1.80 pg in C. lectularius from bats, 2C = 1.68 pg in C. pipistrelli, and 2C = 1.22 pg in Paracimex cf. chaeturus. In the genomes of all cimicid species analyzed, the average GC content ranged from 32.74% in C. pipistrelli to 35.87% in P. cf. chaeturus. Chromosome variability with two male cytotypes, 2n = 28 + X1 X2 Y and 28 + X1 X2 X3 Y, was confirmed in C. pipistrelli. In addition, intraspecific variability in chromosome number was revealed in C. lectularius from bats with 2n = 26 + X1 X2 Y and 26 + X1 X2 X3 Y. We suggest that the origin of intraspecific variability in chromosome number of C. lectularius from bats and C. pipistrelli is not only the result of simple fragmentation, but additive rearrangements like duplications are probably also involved. © 2019 International Society for Advancement of Cytometry.
- MeSH
- Cell Nucleus genetics metabolism MeSH
- Chiroptera MeSH
- Chromosomes genetics MeSH
- Cytogenetic Analysis MeSH
- Genome Size MeSH
- DNA Fragmentation MeSH
- Gonads cytology MeSH
- Humans MeSH
- Ploidies MeSH
- Sex Chromosomes genetics MeSH
- Flow Cytometry MeSH
- Bedbugs genetics metabolism MeSH
- Germ Cells chemistry metabolism MeSH
- Base Composition genetics MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Male MeSH
- Female MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Comparative Study MeSH
Canine babesiosis caused by Babesia canis sensu stricto became an emerging disease of dogs across Europe calling for attention also in countries where it was an only rare imported disease. An easy accessibility of molecular methods and the growing amount of sequencing data led to the description of intraspecific variability in 18S rDNA sequences designated as "genotypes". Using material from a homogenous cohort of dogs with microscopically confirmed canine babesiosis caused by B. canis, we evaluated Babesia intraspecific variability and amplification sensitivity of three different genes (18S rDNA, COI, Cytb) to assess their potential as diagnostic or phylogenetic markers. In raw sequencing data obtained, we observed at least 3 ambiguous positions in up to 86% of chromatograms within the ∼560 bp fragment of 18S rDNA suggesting the existence of several, not identical copies of this gene. Our COI haplotype analysis resulted in a star-like pattern indicating a recent origin of most haplotypes, but not supporting the existence of two dominant haplotypes. Similarly, the Cytb sequences obtained from samples with all variants of 18S rDNA were identical. We corroborate previous observations from three other European countries and bring the evidence of the existence of 18S rDNA paralogs in B. canis genome replacing currently used "genotype" theory.
- MeSH
- Babesia genetics MeSH
- Babesiosis blood diagnosis parasitology MeSH
- Phylogeny MeSH
- Genetic Variation * MeSH
- Genetic Markers MeSH
- Genome, Protozoan MeSH
- Genotype * MeSH
- Haplotypes MeSH
- Cohort Studies MeSH
- Mitochondria genetics MeSH
- Dog Diseases diagnosis parasitology MeSH
- DNA, Protozoan genetics MeSH
- Dogs MeSH
- RNA, Ribosomal, 18S genetics MeSH
- Sequence Analysis, DNA MeSH
- Animals MeSH
- Check Tag
- Dogs MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Geographicals
- Europe MeSH
Structural variations (SVs) such as copy number and presence-absence variations are polymorphisms that are known to impact genome composition at the species level and are associated with phenotypic variations. In the absence of a reference genome sequence, their study has long been hampered in wheat. The recent production of new wheat genomic resources has led to a paradigm shift, making possible to investigate the extent of SVs among cultivated and wild accessions. We assessed SVs affecting genes and transposable elements (TEs) in a Triticeae diversity panel of 45 accessions from seven tetraploid and hexaploid species using high-coverage shotgun sequencing of sorted chromosome 3B DNA and dedicated bioinformatics approaches. We showed that 23% of the genes are variable within this panel, and we also identified 330 genes absent from the reference accession Chinese Spring. In addition, 60% of the TE-derived reference markers were absent in at least one accession, revealing a high level of intraspecific and interspecific variability affecting the TE space. Chromosome extremities are the regions where we observed most of the variability, confirming previous hypotheses made when comparing wheat with the other grasses. This study provides deeper insights into the genomic variability affecting the complex Triticeae genomes at the intraspecific and interspecific levels and suggests a phylogeny with independent hybridization events leading to different hexaploid species.
- Publication type
- Journal Article MeSH
Over time, mountain biota has undergone complex evolutionary histories that have left imprints on its genomic arrangement, geographical distribution and diversity of contemporary lineages. Knowledge on these biogeographical aspects still lags behind for invertebrates inhabiting the Alpine region. In the present study, we examined three scorpion species of the subgenus Euscorpius (Alpiscorpius) from the European Alps using cytogenetic and molecular phylogenetic approaches to determine the variation and population structure of extant lineages at both chromosome and genetic level, and to provide an insight into the species diversification histories. We detected considerable intraspecific variability in chromosome complements and localization of the 18S rDNA loci in all studied species. Such chromosome differences were noticeable as the existence of three [in E. (A.) alpha and E. (A.) germanus] or four [in E. (A.) gamma] range-restricted karyotypic races. These races differed from one another either by 2n [in E. (A.) alpha 2n = 54, 60, 90; in E. (A.) gamma 2n = 58, 60, 88, 86-92], or by the karyotypic formula [in E. (A.) germanus 2n = 34m + 12sm; 36m + 10sm; 42m + 4sm]. Using mitochondrial (16S rRNA, COI) and nuclear (28S rDNA) genetic markers, we examined genetic variation and reconstructed phylogenetic relationships among the karyotypic races. Both approaches provided evidence for the existence of ten deeply divergent lineages exhibiting the features of local endemics and indicating the presence of cryptic species. Molecular dating analyses suggest that these lineages diversified during the Plio-Pleistocene and this process was presumably accompanied by dynamic structural changes in the genome organization.
- MeSH
- Alleles MeSH
- Time Factors MeSH
- Chromosomes genetics MeSH
- Species Specificity MeSH
- Phylogeny MeSH
- Genetic Variation * MeSH
- Genome MeSH
- Karyotyping MeSH
- Evolution, Molecular * MeSH
- DNA, Ribosomal genetics MeSH
- RNA, Ribosomal, 16S genetics MeSH
- Scorpions genetics MeSH
- Geography MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
BACKGROUND: Chromosomal rearrangements have the potential to limit the rate and pattern of gene flow within and between species and thus play a direct role in promoting and maintaining speciation. Wood white butterflies of the genus Leptidea are excellent models to study the role of chromosome rearrangements in speciation because they show karyotype variability not only among but also within species. In this work, we investigated genome architecture of three cryptic Leptidea species (L. juvernica, L. sinapis and L. reali) by standard and molecular cytogenetic techniques in order to reveal causes of the karyotype variability. RESULTS: Chromosome numbers ranged from 2n = 85 to 91 in L. juvernica and 2n = 69 to 73 in L. sinapis (both from Czech populations) to 2n = 51 to 55 in L. reali (Spanish population). We observed significant differences in chromosome numbers and localization of cytogenetic markers (rDNA and H3 histone genes) within the offspring of individual females. Using FISH with the (TTAGG) n telomeric probe we also documented the presence of multiple chromosome fusions and/or fissions and other complex rearrangements. Thus, the intraspecific karyotype variability is likely due to irregular chromosome segregation of multivalent meiotic configurations. The analysis of female meiotic chromosomes by GISH and CGH revealed multiple sex chromosomes: W1W2W3Z1Z2Z3Z4 in L. juvernica, W1W2W3Z1Z2Z3 in L. sinapis and W1W2W3W4Z1Z2Z3Z4 in L. reali. CONCLUSIONS: Our results suggest a dynamic karyotype evolution and point to the role of chromosomal rearrangements in the speciation of Leptidea butterflies. Moreover, our study revealed a curious sex determination system with 3-4 W and 3-4 Z chromosomes, which is unique in the Lepidoptera and which could also have played a role in the speciation process of the three Leptidea species.
- MeSH
- Biological Evolution * MeSH
- Histones genetics MeSH
- Insect Proteins genetics MeSH
- Karyotype MeSH
- Butterflies classification genetics MeSH
- Sex Chromosomes MeSH
- Sex Determination Processes * MeSH
- DNA, Ribosomal genetics MeSH
- Gene Flow MeSH
- Animals MeSH
- Check Tag
- Male MeSH
- Female MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
The North American spiny-cheek crayfish, Orconectes limosus (Cambaridae), endangered in its native range, is a widespread invasive species in European waters and conservationally important carrier of crayfish plague. However, its population structure is poorly known, and no informative genetic markers for the species are available. We tested cross-species transfer of microsatellite loci to spiny-cheek crayfish from 5 other crayfish species. Variability of 10 successfully amplifying loci derived from 4 species was then tested in 60 individuals of O. limosus originating from 3 natural populations: the river Danube at Bogyiszló in Hungary, a pond in Starý Klíèov, and the brook Eernovický, both in the Czech Republic. The allele number within the populations ranged from 4 to 10 alleles per locus, while heterozygosity levels varied from 0.650 to 0.900 for H(o) and from 0.660 to 0.890 for H(e). No linkage disequilibrium and no null alleles were detected. The selected markers are useful for assessing population structure, intraspecific variation, and paternity studies in spiny-cheek crayfish.
The literature suggests that small genomes promote invasion in plants, but little is known about the interaction of genome size with other traits or about the role of genome size during different phases of the invasion process. By intercontinental comparison of native and invasive populations of the common reed Phragmites australis, we revealed a distinct relationship between genome size and invasiveness at the intraspecific level. Monoploid genome size was the only significant variable that clearly separated the North American native plants from those of European origin. The mean Cx value (the amount of DNA in one chromosome set) for source European native populations was 0.490 ± 0.007 (mean ± SD), for North American invasive 0.506 ± 0.020, and for North American native 0.543 ± 0.021. Relative to native populations, the European populations that successfully invaded North America had a smaller genome that was associated with plant traits favoring invasiveness (long rhizomes, early emerging abundant shoots, resistance to aphid attack, and low C:N ratio). The knowledge that invasive populations within species can be identified based on genome size can be applied to screen potentially invasive populations of Phragmites in other parts of the world where they could grow in mixed stands with native plants, as well as to other plant species with intraspecific variation in invasion potential. Moreover, as small genomes are better equipped to respond to extreme environmental conditions such as drought, the mechanism reported here may represent an emerging driver for future invasions and range expansions.
Polyploidization has played an important role in the evolution of vertebrates, particularly at the base of Teleostei-an enormously successful ray-finned fish group with additional genome doublings on lower taxonomic levels. The investigation of post-polyploid genome dynamics might provide important clues about the evolution and ecology of respective species and can help to decipher the role of polyploidy per se on speciation. Few studies have attempted to investigate the dynamics of repetitive DNA sequences in the post-polyploid genome using molecular cytogenetic tools in fishes, though recent efforts demonstrated their usefulness. The demonstrably monophyletic freshwater loach family Botiidae, branching to evolutionary diploid and tetraploid lineages separated >25 Mya, offers a suited model group for comparing the long-term repetitive DNA evolution. For this, we integrated phylogenetic analyses with cytogenetical survey involving Giemsa- and Chromomycin A3 (CMA3)/DAPI stainings and fluorescence in situ hybridization with 5S/45S rDNA, U2 snDNA and telomeric probes in representative sample of 12 botiid species. The karyotypes of all diploids were composed of 2n = 50 chromosomes, while majority of tetraploids had 2n = 4x = 100, with only subtle interspecific karyotype differences. The exceptional karyotype of Botia dario (2n = 4x = 96) suggested centric fusions behind the 2n reduction. Variable patterns of FISH signals revealed cases of intraspecific polymorphisms, rDNA amplification, variable degree of correspondence with CMA3+ sites and almost no phylogenetic signal. In tetraploids, either additivity or loci gain/loss was recorded. Despite absence of classical interstitial telomeric sites, large blocks of interspersed rDNA/telomeric regions were found in diploids only. We uncovered different molecular drives of studied repetitive DNA classes within botiid genomes as well as the advanced stage of the re-diploidization process in tetraploids. Our results may contribute to link genomic approach with molecular cytogenetic analyses in addressing the origin and mechanism of this polyploidization event.
- MeSH
- Biological Evolution * MeSH
- Diploidy * MeSH
- Phylogeny MeSH
- Karyotyping MeSH
- Cypriniformes classification genetics MeSH
- DNA, Ribosomal genetics MeSH
- Tandem Repeat Sequences * MeSH
- Tetraploidy * MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
