Comparative Cytogenetics最新文献

In this paper, we present new cytogenetic data for three species of the family Pentatomidae: Dichelops melacanthus (Dallas, 1851), Loxa viridis (Palisot de Beauvois, 1805), and Edessa collaris (Dallas, 1851). All studied species presented holocentric chromosomes and inverted meiosis for the sex chromosomes. D. melacanthus has 2n = 12 (10A + XY); L. viridis showed 2n = 14 (12A + XY); and E. collaris showed 2n = 14 (12A + XY). C-banding was performed for the first time in these species and revealed terminal and interstitial heterochromatic regions on the autosomes; DAPI/CMA₃ staining showed different fluorescent patterns. In all species, fluorescence in situ hybridization (FISH) with 18S rDNA probe identified signals on one autosomal bivalent, this being the first report of FISH application in the species D. melacanthus and L. viridis. The results obtained add to those already existing in the literature, enabling a better understanding of the meiotic behavior of these insects.

Chromosomal and molecular analyses of rapidly evolving organisms such as Polyommatus Latreille, 1804 blue butterflies are essential for understanding their taxonomy and evolutionary history, and the studies of populations from their type localities are crucially important for resolving problems of nomenclature and species identity. Here we present data on the topotypical population of the blue butterfly species described as Lycaena damone var. cyanea Staudinger, 1899. This taxon was described from Khankendi (Nagorno-Karabakh, Caucasus), and rediscovered at the type locality for the first time since it was collected there in 1869. The specimens were found on dry stony meadows with a predominance of Onobrychis radiata Bieberstein, 1810, on upper border of oak forests. Their haploid chromosome number (n) was established as n = 17. Chromosomal and mitochondrial DNA barcode analyses of the studied samples from type-locality provided an opportunity for the critical taxonomic re-examination of Caucasian species of the subgenus Agrodiaetus Hübner, 1822 of the genus Polyommatus Latreille, 1804. The obtained data support the interpretation of the P. (A.) cyaneus (Staudinger, 1899) and P. (A.) carmon (Herrich-Schäffer, 1851) as two different, not closely related species complexes as previously hypothesized by Hugo de Lesse. On the contrary, the treatment by Walter Forster who considered these taxa as two groups of conspecific populations was not supported by our data.

For the first time, cytogenetic features of grasshoppers from Iran have been studied. In this paper we conducted a comparative cytogenetic analysis of six species from the family Pamphagidae. The species studied belong to subfamilies Thrinchinae Stål, 1876 (Eremopeza bicoloripes (Moritz, 1928), E. saussurei (Uvarov, 1918)) and Pamphaginae (Saxetania paramonovi (Dirsh, 1927), Tropidauchen escalerai Bolívar, 1912, Tropidauchen sp., and Paranothrotes citimus Mistshenko, 1951). We report information about the chromosome number and morphology, C-banding patterns, and localization of ribosomal DNA clusters and telomeric (TTAGG)_n repeats. Among these species, only S. paramonovi had an ancestral Pamphagidae karyotype (2n=18+X0♂; FN=19♂). The karyotypes of the remaining species differed from the ancestral karyotypes. The karyotypes of E. bicoloripes and E. saussurei, despite having the same chromosome number (2n=18+X0♂) had certain biarmed chromosomes (FN=20♂ and FN=34♂ respectively). The karyotypes of T. escalerai and Tropidauchen sp. consisted of eight pairs of acrocentric autosomes, one submetacentric neo-X chromosome and one acrocentric neo-Y chromosome in males (2n=16+neo-X neo-Y♂). The karyotype of P. citimus consisted of seven pairs of acrocentric autosomes, submetacentric the neo-X₁ and neo-Y and acrocentric the neo-X₂ chromosomes (2n=14+neo-X₁ neo-X₂ neo-Y♂). Comparative analysis of the localization and size of C-positive regions, the position of ribosomal clusters and the telomeric DNA motif in the chromosomes of the species studied, revealed early unknown features of their karyotype evolution. The data obtained has allowed us to hypothesize that the origin and early phase of evolution of the neo-Xneo-Y♂ sex chromosome in the subfamily Pamphaginae, are linked to the Iranian highlands.

The karyotypes of four species of Cleridae (Coleoptera): Trichodes favarius (Illiger, 1802), Trichodes quadriguttatus Adams, 1817, Trichodes reichei (Mulsant et Rey, 1863), and Tilloidea transversalis (Charpentier, 1825) were reported for the first time with this study. The chromosome numbers of these four species were determined as 2n = 18, sex chromosome system Xy_p, and all chromosomes were metacentric (the except y chromosome). Together with this study, the chromosome data of only 17 species are available in this family. It is remarkable that all of them display the same chromosome number and similar karyotypes. This may make the effect of karyotypical features important in interpreting the evolutionary process of Cleridae.

The ancient insect order Odonata is divided into three suborders: Anisoptera and Zygoptera with approximately 3000 species worldwide each, and Anisozygoptera with only four extant species in the relict family Epiophlebiidae. An updated list of Odonata species studied regarding chromosome number, sex chromosome mechanism and the occurrence of m-chromosomes (= microchromosomes) is given. Karyotypes of 607 species (198 genera, 23 families), covering approximately 10% of described species, are reported: 423 species (125 genera, 8 families) of the Anisoptera, 184 species (72 genera, 14 families) of the Zygoptera, and one species of the Anisozygoptera. Among the Odonata, sex determination mechanisms in males can be of X(0), XY and X₁X₂Y types, and diploid chromosome numbers can vary from 6 to 41, with a clear mode at 2n = 25(60%) and two more local modes at 2n = 27(21%) and 2n = 23(13%). The karyotype 2n = 25(24A + X) is found in each of the three suborders and is the most typical (modal) in many families, including the best-covered Libellulidae, Corduliidae (Anisoptera), Lestidae, Calopterygidae, and Platycnemididae (Zygoptera). This chromosome set is considered ancestral for the Odonata in general. Chromosome rearrangements, among which fusions and fissions most likely predominated, led to independent origins of similar karyotypes within different phylogenetic lineages of the order. The karyotype 2n = 27(26A + X) prevails in Aeshnidae and Coenagrionidae, whereas the karyotype 2n = 23(22A + X) is modal in Gomphidae and Chlorocyphidae, in both pairs of families one being from the Anisoptera while the other from the Zygoptera.

The DNA-barcoding and chromosomal study of the eastern water bat, Myotis petax Hollister, 1912, from the earlier unexplored localities in the Russian Far East are carried out. The COI barcoding obtained for 18 from a total of 19 individuals captured in five localities in the Russian Far East showed the low nucleotide variability with the prevalence of the central, the most abundant haplotype. The chromosomal characteristics of eight M. petax specimens (2n = 44, NFa = 52) in the Russian Far East are clarified. The number and localization of NOR in karyotype of M. petax is described at the first time and differ from distributional patterns of NOR in the sibling species M. daubentonii Kuhl, 1819 that can be used as diagnostic feature. The considerable intraspecific variability in the distribution of heterochromatin material revealed is not typical of the genus Myotis, but it has been found in other species of the family Vespertilionidae.

The assembly of the microtubule-based spindle structure in plant meiosis remains poorly understood compared with our knowledge of mitotic spindle formation. One of the approaches in our understanding of microtubule dynamics is to study spindle assembly in meiosis of amphyhaploids. Using immunostaining with phH3Ser10, CENH3 and α-tubulin-specific antibodies, we studied the chromosome distribution and spindle organisation in meiosis of F₁ 2R(2D)xR wheat-rye hybrids (genome structure ABDR, 4× = 28), as well as in wheat and rye mitosis and meiosis. At the prometaphase of mitosis, spindle assembly was asymmetric; one half of the spindle assembled before the other, with simultaneous chromosome alignment in the spindle mid-zone. At diakinesis in wheat and rye, microtubules formed a pro-spindle which was subsequently disassembled followed by a bipolar spindle assembly. In the first meiosis of hybrids 2R(2D)xR, a bipolar spindle was not found and the kinetochore microtubules distributed the chromosomes. Univalent chromosomes are characterised by a monopolar orientation and maintenance of sister chromatid and centromere cohesion. Presence of bivalents did not affect the formation of a bipolar spindle. Since the central spindle was absent, phragmoplast originates from "interpolar" microtubules generated by kinetochores. Cell plate development occurred with a delay. However, meiocytes in meiosis II contained apparently normal bipolar spindles. Thus, we can conclude that: (1) cohesion maintenance in centromeres and between arms of sister chromatids may negatively affect bipolar spindle formation in the first meiosis; (2) 2R/2D rye/wheat chromosome substitution affects the regulation of the random chromosome distribution in the absence of a bipolar spindle.

An overview of the current knowledge of chromosome sets of the parasitoid superfamily Chalcidoidea is given. Karyotypes of approximately 240 members of this group, i.e. just above one percent of described species, are studied up to now. Techniques for obtaining and analyzing preparations of chalcid chromosomes are outlined, including the so-called "traditional" and "modern" methods of differential staining as well as fluorescence in situ hybridization (FISH). Among the Chalcidoidea, the haploid chromosome number can vary from n = 3 to n = 11, with a clear mode at n = 6 and a second local maximum at n = 10. In this group, most chromosomes are either metacentric or submetacentric, but acrocentrics and/or subtelocentrics also can predominate, especially within karyotypes of certain Chalcidoidea with higher chromosome numbers. The following main types of chromosomal mutations are characteristic of chalcid karyotypes: inversions, fusions, translocations, polyploidy, aneuploidy and B chromosome variation. Although karyotype evolution of this superfamily was mainly studied using phylogenetic reconstructions based on morphological and/or molecular characters, chromosomal synapomorphies of certain groups were also revealed. Taxonomic implications of karyotypic features of the Chalcidoidea are apparently the most important at the species level, especially among cryptic taxa.

The centromere is a chromosomal region where the kinetochore is formed, which is the attachment point of spindle fibers. Thus, it is responsible for the correct chromosome segregation during cell division. Telomeres protect chromosome ends against enzymatic degradation and fusions, and localize chromosomes in the cell nucleus. For this reason, centromeres and telomeres are parts of each linear chromosome that are necessary for their proper functioning. More and more research results show that the identity and functions of these chromosomal regions are epigenetically determined. Telomeres and centromeres are both usually described as highly condensed heterochromatin regions. However, the epigenetic nature of centromeres and telomeres is unique, as epigenetic modifications characteristic of both eu- and heterochromatin have been found in these areas. This specificity allows for the proper functioning of both regions, thereby affecting chromosome homeostasis. This review focuses on demonstrating the role of epigenetic mechanisms in the functioning of centromeres and telomeres in plants and animals.

To extend our knowledge on karyotype variation of the genus Vigna Savi, 1824, the chromosomal organization of rRNA genes and fluorochrome banding patterns of five wild Vigna species were studied. Sequential combined PI (propidium iodide) and DAPI (4',6-diamidino-2-phenylindole) (CPD) staining and fluorescence in situ hybridization (FISH) with 5S and 45S rDNA probes were used to analyze the karyotypes of V. luteola (Jacquin, 1771) Bentham, 1959, V. vexillata (Linnaeus, 1753) A. Richard, 1845, V. minima (Roxburgh, 1832) Ohwi & H. Ohashi, 1969, V. trilobata (Linnaeus, 1753) Verdcourt, 1968, and V. caracalla (Linnaeus, 1753) Verdcourt,1970. For further phylogenetic analysis, genomic in situ hybridization (GISH) with the genomic DNA of V. umbellata (Thunberg, 1794) Ohwi & H.Ohashi, 1969 onto the chromosomes of five wild Vigna species was also performed. Detailed karyotypes were established for the first time using chromosome measurements, fluorochrome bands, and rDNA-FISH signals. All species had chromosome number 2n = 2x = 22, and symmetrical karyotypes that composed of only metacentric or metacentric and submetacentric chromosomes. CPD staining revealed all 45S rDNA sites in the five species analyzed, (peri)centromeric GC-rich heterochromatin in V. luteola, V. trilobata and V. caracalla, interstitial GC-rich and pericentromeric AT-rich heterochromatin in V. caracalla. rDNA-FISH revealed two 5S loci in V. caracalla and one 5S locus in the other four species; one 45S locus in V. luteola and V. caracalla, two 45S loci in V. vexillata and V. trilobata, and five 45S loci in V. minima. The karyotypes of the studied species could be clearly distinguished by the karyotypic parameters, and the patterns of the fluorochrome bands and the rDNA sites, which revealed high interspecific variation among the five species. The V. umbellata genomic DNA probe produced weak signals in all proximal regions of V. luteola and all (peri)centromeric regions of V. trilobata. The combined data demonstrate that distinct genome differentiation has occurred among the five species during evolution. The phylogenetic relationships between the five wild species and related cultivated species of Vigna are discussed based on our present and previous molecular cytogenetic data.