acrocentric
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Rainbowfishes (Melanotaeniidae) are the largest monophyletic group of freshwater fishes occurring in Australia and New Guinea, with 112 species currently recognised. Despite their high taxonomic diversity, rainbowfishes remain poorly studied from a cytogenetic perspective. Using conventional (Giemsa staining, C banding, chromomycin A3 staining) and molecular (fluorescence in situ hybridisation with ribosomal DNA (rDNA) and telomeric probes) cytogenetic protocols, karyotypes and associated chromosomal characteristics of five species were examined. We covered all major lineages of this group, namely, Running River rainbowfish Melanotaenia sp., red rainbowfish Glossolepisincisus, threadfin rainbowfish Iriatherina werneri, ornate rainbowfish Rhadinocentrus ornatus, and Cairns rainbowfish Cairnsichthys rhombosomoides. All species had conserved diploid chromosome numbers 2n = 48, but karyotypes differed among species; while Melanotaenia sp., G. incisus, and I. werneri possessed karyotypes composed of exclusively subtelo/acrocentric chromosomes, the karyotype of R. ornatus displayed six pairs of submetacentric and 18 pairs of subtelo/acrocentric chromosomes, while C. rhombosomoides possessed a karyotype composed of four pairs of submetacentric and 20 pairs of subtelo/acrocentric chromosomes. No heteromorphic sex chromosomes were detected using conventional cytogenetic techniques. Our data indicate a conserved 2n in Melanotaeniidae, but morphologically variable karyotypes, rDNA sites, and heterochromatin distributions. Differences were observed especially in taxonomically divergent species, suggesting interspecies chromosome rearrangements.
- MeSH
- fylogeneze MeSH
- karyotyp * MeSH
- polymorfismus genetický * MeSH
- ribozomální DNA genetika MeSH
- ryby klasifikace genetika MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The karyotype and other chromosomal characteristics the crucian carp (Carassius carassius (Linnaeus, 1758)) were revealed by means of conventional banding protocols (C, CMA3, AgNOR). The diploid chromosome number (2n) in this species was 100. Its karyotype was composed of 10 pairs of metacentric, 18 pairs of submetacentric and 22 pairs of subtelo- to acrocentric chromosomes without any microchromosomes. C-banding identified blocks of telomeric heterochromatin on seven chromosome pairs. The NORs were situated on the p arms of the 14(th) pair of submetacentric chromosomes and on the p arms of the 32(nd) pair of subtelo-acrocentric chromosomes; AgNOR-positive signals corresponded to the CMA3-positive signals. These chromosome characteristics may suggest a paleo-allotetraploid origin of Carassius carassius genome.
- Publikační typ
- časopisecké články MeSH
The karyotype of Greek cobitid fish Cobitisstrumicae Karaman, 1955, from Lake Volvi, Greece, a representative of one of its two major intraspecific phylogenetic lineages, was analysed by means of sequential Giemsa-staining, C-banding, silver-staining, CMA3 fluorescence banding and also by in situ hybridization (FISH) with rDNA probe. The diploid chromosome number was 2n = 50, karyotype composed of 10 pairs of metacentric to submetacentric and 15 pairs of subtelocentric to acrocentric chromosomes. The nucleolus organizer regions (NORs) as revealed by Ag- and CMA3 staining and FISH were situated in the telomeric region of the fourth submetacentric chromosome pair. The chromosomes contained very low content of C-positive heterochromatin. No heteromorphic sex chromosomes were detected. This first karyotype report for any species of lineage Bicanestrinia Băcescu, 1962 shows a simple karyotype dominated by acrocentric chromosomes and possessing single NOR-bearing chromosome pair. Cytotaxonomic implications of this finding for the taxonomy of the genus Cobitis Linnaeus, 1758 are further discussed.
- Publikační typ
- časopisecké články MeSH
Karyotypic data from Australian native freshwater fishes are scarce, having been described from relatively few species. Golden perch (Macquaria ambigua) and Murray cod (Maccullochella peelii) are two large-bodied freshwater fish species native to Australia with significant indigenous, cultural, recreational and commercial value. The arid landscape over much of these fishes' range, coupled with the boom and bust hydrology of their habitat, means that these species have potential to provide useful evolutionary insights, such as karyotypes and sex chromosome evolution in vertebrates. Here we applied standard and molecular cytogenetic techniques to characterise karyotypes for golden perch and Murray cod. Both species have a diploid chromosome number 2n = 48 and a male heterogametic sex chromosome system (XX/XY). While the karyotype of golden perch is composed exclusively of acrocentric chromosomes, the karyotype of Murray cod consists of two submetacentric and 46 subtelocentric/acrocentric chromosomes. We have identified variable accumulation of repetitive sequences (AAT)10 and (CGG)10 along with diverse methylation patterns, especially on the sex chromosomes in both species. Our study provides a baseline for future cytogenetic analyses of other Australian freshwater fishes, especially species from the family Percichthyidae, to better understand their genome and sex chromosome evolution.
- MeSH
- druhová specificita MeSH
- fylogeneze MeSH
- karyotyp * MeSH
- metafáze MeSH
- metylace DNA genetika MeSH
- mikrosatelitní repetice genetika MeSH
- okounovití genetika MeSH
- Perciformes genetika MeSH
- pohlavní chromozomy genetika MeSH
- pruhování chromozomů MeSH
- sladká voda * MeSH
- telomery genetika MeSH
- zeměpis MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
In terms of cytogenetics, entelegyne araneomorphs are the best studied clade of spiders. The typical karyotype of entelegyne males consists of acrocentric chromosomes, including 2 non-homologous X chromosomes. The present study is focused on the karyotype, nucleolus organising regions (NORs) and sex chromosome behaviour during meiosis of the entelegyne Wadicosa fidelis (Lycosidae). Preparations stained by Giemsa were used to study karyotype and meiosis. NORs were visualised by silver staining and fluorescence in situ hybridisation with 18S rDNA probe. The male karyotype consists of 28 acrocentric elements, including 2 X chromosomes. In contrast to the majority of other spiders, the male sex chromosomes pair during the major part of meiosis. Following an initial period of parallel pairing, the attachment of male sex chromosomes is restricted to centromeric areas and continues until metaphase II. Our study revealed an enormous number of NORs in the population from Galilee and indicates a considerable variability of NOR numbers in this population. The distal regions of 9 or 10 autosomal pairs contain NORs. The obtained data indicate the rapid spread of NORs in the karyotype of W. fidelis, which was presumably caused by ectopic recombinations and subsequent hybridisations of individuals with different NOR genotypes that produced heterozygotes.
- MeSH
- centromera genetika MeSH
- chromozom X genetika MeSH
- detekce genetických nosičů MeSH
- DNA sondy genetika MeSH
- druhová specificita MeSH
- karyotyp MeSH
- meióza MeSH
- metafáze MeSH
- organizátor jadérka genetika MeSH
- pavouci genetika MeSH
- polymorfismus genetický * MeSH
- rekombinace genetická MeSH
- RNA ribozomální 18S genetika MeSH
- spermatogeneze MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
To study 3D nuclear distributions of epigenetic histone 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, combined 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 dimeH3( 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.
- MeSH
- acetylace účinky léků MeSH
- centromera genetika metabolismus MeSH
- chromozom X genetika metabolismus MeSH
- financování organizované využití MeSH
- histony metabolismus MeSH
- interfáze fyziologie genetika MeSH
- interpretace obrazu počítačem metody využití MeSH
- konfokální mikroskopie metody využití MeSH
- metylace účinky léků MeSH
