Čeleď brukvovitých patří k největším rostlinným čeledím; zahrnuje 49 tribů, 321 rodů a 3 660 druhů. Zájem vědců o tuto rostlinnou skupinu vzrostl především díky ustanovení huseníčku rolního (Arabidopsis thaliana) modelovým druhem a sekvenování jeho genomu. To v r. 2000 odstartovalo mimo jiné bouřlivý rozvoj srovnávací fylogenomiky a cytogenomiky, včetně úspěšného zavedení metody malování chromozomů (chromosome painting) huseníčku a její aplikace na další zástupce brukvovitých (srovnávací malování chromozomů; comparative chromosome painting, CCP). Metoda CCP umožňuje studium chromozomové kolinearity, rozpoznání chromozomových přestaveb, porovnání struktury chromosomů nebo jejich částí mezi jednotlivými druhy a rekonstrukci struktury celých karyotypů. Brukvovité jsou jedinou rostlinnou čeledí, u níž je v tomto rozsahu metoda CCP použitelná. Srovnávací cytogenetické mapy brukvovitých tak představují zcela unikátní typ dat o evoluci rostlinných karyotypů a genomů., Whole-genome sequencing of the model plant Arabidopsis thaliana has stimulated a rapid development of comparative phylogenomics and cytogenomics, including the invention of chromosome painting in A. thaliana and comparative chromosome painting (CCP) in other species of the Brassicaceae (Cruciferae) family. This is the only plant family in which large-scale CCP is feasible. CCP provides unique insights into the karyotype and genome evolution in plants by comparing chromosome collinearity, identification of chromosome rearrangements, construction of comparative cytogenetic maps, and reconstruction of ancestral karyotype structures., and Terezie Mandáková.
In the course of cytogenetic studies on Alegoria castelnaui Fleutiaux & Sallé 1889 (Coleoptera: Tenebrionidae: Tenebrioninae: Ulomini) from Guadeloupe, a number of adult specimens were dissected. A larva was found in the abdomens of almost all of the females. The karyotype, 20,XX / 20,Xyp, and the presence of heterochromatin at multiple chromosomal locations, of the larvae and adults were similar, which excludes parasitism and indicates viviparous reproduction. The adverse habitat of the adults, i.e., putrid and fermenting pseudo-stems of banana trees rather than geo-climatic conditions, may explain the occurrence of viviparity in this species. This is the first example of (ovo-)viviparity in the Ulomini tribe and among New World Tenebrionidae. A. castelnaui is regularly collected on banana trees infested with the weevil Cosmopolites sordidus Germar, 1824, a major pest of banana trees around the word. The coexistence of these two species on banana trees may be coincidental but another Ulomini species, Eutochia pulla Erichson 1843, is described as an egg predator of C. sordidus in Africa and therefore, A. castelnaui could also be a predator of this pest.
The meadow spittlebug genus Philaenus (Auchenorrhyncha: Aphrophoridae) is known to display marked colour polymorphism. This study presents the results of a karyotype analysis of P. arslani from Lebanon using conventional chromosome staining, C-banding, fluorescent banding using base-specific fluorochromes (CMA3 and DAPI) and AgNOR-staining. This species has 2n = 18 + neo-XY, and differs from P. spumarius both in the number of chromosomes and sex chromosome system. During meiosis, the neo-XY bivalent is clearly heteromorphic being the largest in the complement. Furthermore, sex chromosomes show marked differences in C-banding pattern. The NOR-bearing chromosomes are the first and one of the middle-sized pairs of autosomes. NORs are G-C rich. Furthermore, some blocks of constitutive heterochromatin on the sex chromosomes are also G-C rich. All other C-bands are DAPI or DAPI/ CMA3 positive, thus containing A-T rich DNA. The significant difference in the karyotype of P. arslani and P. spumarius indicates chromosomal transformations during the evolution of the genus Philaenus.
In the present work, we have characterized the chromosomes of 13 Cassidinae beetles, belonging to four tribes, the broad aim being to increase the cytogenetic data and establish the mechanisms involved in chromosome evolution of this subfamily, which appear to be conserved karyotypically, i.e. 2n = 16 + Xyp. The analysis of mitotic and meiotic cells revealed a high diversity of diploid numbers (2n = 18, 2n = 22, 2n = 26, 2n = 32, 2n = 36, 2n = 40, 2n = 42), and the presence of sex chromosome system of the Xyp type in most species, with the exception of two representatives that exhibited Xyr and XY systems. C-banding showed constitutive heterochromatin predominantly localized in the pericentromeric region of the chromosomes, but differences regarding the number of chromosomes with positive C-bands, intensity of the blocks, and presence of additional bands in autosomes and/or sex chromosomes were observed among the species investigated. Our data revealed that the karyotype 2n = 16 + Xyp does not occur in all 13 tribes of the Cassidinae characterized cytogenetically, seeming to be only a shared feature among the species of the Cassidini. Variations in the C-band pattern, mainly in closely related species, suggest that the interspecific karyotype diversification occurred as a result of changes in the quantity and distribution of constitutive heterochromatin. The occurrence of the Xyp sex chromosome system in the tribe Mesomphaliini, which showed the highest diversity of simple and multiple systems among the coleopteran as a whole, reinforces the view that derived systems originated by chromosome rearrangements involving the Xyp ancestral system., Amália T. Lopes, Flávia R. Fernandes, Marielle C. Schneider., and Obsahuje bibliografii
To study 3D nuclear distributions of epigenetic hist one modifications such as H3(K9) acetylation, H3(K4) dimethylation, H3(K9) dimethylation, and H3(K27) trimethylation, and of histone methyltransferase Suv39H1, we used advanced image analysis methods, comb ined with Nipkow disk confocal microscopy. Total fluorescence intensity and distributions of fluorescently labelled proteins were analyzed in formaldehyde-fixed interphase nuclei. Our data showed reduced fluorescent signals of H3(K9) acetylation and H3(K4) dimethylation (di-me) at the nuclear periphery, while di-meH3(K9) was also abundant in chromatin regions closely associated with the nuclear envelope. Little overlapping (intermingling) was observed for di-meH3(K4) and H3(K27) trimethylation (tri-me), and for di-meH3(K9) and Suv39H1. The histone modifications studied were absent in the nucleolar compartment with the exception of H3(K9) dimethylation that was closely associated with perinucleolar regions which are formed by centromeres of acrocentric chromosomes. Using immunocytochemistry, no di-meH3(K4) but only dense di-meH3(K9) was found for the human acrocentric chromosomes 14 and 22. The active X chromosome was observed to be partially acetylated, while the inactive X was more condensed, located in a very peripheral part of the interphase nuclei, and lacked H3(K9) acetylation. Our results confirmed specific interphase patterns of histone modifications within the interphase nuclei as well as within their chromosome territories., M. Skalníková, E. Bártová, V. Ulman, P. Matula, D. Svoboda, A. Harničarová, M. Kozubek, S. Kozubek., and Obsahuje bibliografii a bibliografické odkazy
Screening of nuclear genome size was carried out on ca 2400 plants from over 120 mainly Central- European localities of the Juncus bufonius group. Besides the diploid level, corresponding to known diploid species (in this case J. ranarius, J. hybridus and J. sorrentini), two polyploid cytotypes were detected, conforming with the tetraploid and hexaploid levels treated by some authors as separate species: J. minutulus and J. bufonius s. str. The relationship between nuclear DNA content and the number of chromosomes was verified by chromosome counting. Polyploidy, as opposed to agmatoploidy can, therefore, account for the karyological variation. The 2C values of diploid, tetraploid and hexaploid individuals were ca 0.65, 1.18±2.8% and 1.84±1.6% pg 2C DNA, respectively. No other cytotype or statistically significant variation in nuclear genome size was found. To asses the utility of hitherto published morphological characters distinguishing J. minutulus from J. bufonius s. str., measurements of seven floral and three vegetative quantitative characters were obtained (no less than 10 measurements per flower, 30 per plant) for 358 mature plants of known ploidy level from 47 localities. Diverse ordination and clustering techniques did not indicate the presence of any grouping in the dataset. Canonical discriminant analysis and stepwise variable selection indicated that inner tepal length followed by mean capsule width and mean capsule length were the most useful characters for identifying the two ploidy levels; however, the estimated 10-fold cross-validation error rate of a simple k nearest neighbour classification analysis was 0.45. Other analyses corroborated this result. No new morphological character that would allow successful separation of tetraploids from hexaploids was discovered. This provides independent support for the opinion of some previous authors that J. bufonius L. is best treated as a single variable species comprising two cytotypes that are inseparable using hitherto suggested diagnostic characters until convincing proof to the contrary is available.
Natural occurrence of pentaploid loach, Misgurnus anguillicaudatus
discovered from Liangzi Lake area, Hubei Province, central China, is reported here for the first time. The evidences from karyotyping, DNA content analysis and nuclear volume measurements were described to confirm the pentaploid nature of the identified individual. This individual was phenotypically indistinguishable from its sympatric diploid and tetraploid counterparts. The chromosome number was 5n = 125, the mean erythrocyte nuclear DNA content was 2.62 and 1.25 times of their diploid and tetraploid counterparts, respectively. An origin of such polyploidy form either from genome addition of normal sperm nuclei to unreduced egg and the mating of tetraploid individual and hexaploid individual, respectively, is hypothesized.
The distribution patterns of the X0/XX and neo-XY/neo-XX chromosome races, subraces, and "hybrids" between subraces of the grasshopper P. sapporensis were analyzed. The origin of the observed variation is Robertsonian translocations between a sex chromosome and an autosome, and chromosome rearrangements. The fixation levels of inversions varied depending on geographic regions. No hybrid population is known implying that a strong reproductive isolation system exists in hybrids between the different chromosomal races. The probable reasons for the purity of X0 and neo-XY chromosome races and high chromosome polymorphism in contact zones between chromosomal subraces are discussed. The presence of isolating barriers between chromosome races indicates a review of the taxonomic structure of P. sapporensis is required. It is proposed to divide P. sapporensis into two sibling species, which differ in the chromosome mechanisms of the sex determination system.The analysis of the distribution of chromosomal races and subraces of P. sapporensis allows a reconstruction of the history of this species in the Okhotsk sea region.
The karyotype of bream Abramis brama was analysed by means of C-banding, replication banding, DAPI fluorescent staining and in situ hybridisation with 18S rDNA and telomeric probes. The use of the in vivo 5-bromodeoxyuridine incorporation technique enabled the induction of replication bands of the RBA type in the karyotype. C-bands corresponded to late replicated chromosome regions. 18S rDNA clusters were found on one chromosome pair. Telomeric sequences were observed only on ends of chromatids. The karyotype morphology and NOR phenotype of A. brama are very similar to those found in other species of the leuciscine cyprinids karyotyped so far.
This study reports for the first time the banding pattern on chromosomes of the Tatra vole, Microtus tatricus, as revealed by G-, C-, and Ag-NOR staining procedures. The banded karyotype of M. tatricus was compared with Microtus (Terricola) subterraneus, M. (Stenocranius) gregalis, and M. (Blanfordimys) aghanus. The karyotype of M. tatricus possesses highly derived features, e.g., the low diploid number of chromosomes or unique combinations of arms in the biarmed autosomes. It is almost impossible to find clear relationships of M. tatricus with other extant vole species from the point of view of comparative karyology. The karyotypic changes in voles are apparently not accompanied by adequate divergence in morphological and genetic traits.