Cytology of polytene chromosomes in chironomus, Mycetophila and Rhagoletis. II. Chromosomal rearrangements, puffing and nucleolar-organizer.

Abstract Background DNA tandem repeats (TRs) are often abundant and occupy discrete regions in eukaryotic genomes. These TRs often cause or generate chromosomal rearrangements, which, in turn, drive chromosome evolution and speciation. Tracing the chromosomal distribution of TRs could therefore provide insights into the chromosome dynamics and speciation among closely related taxa. The basic chromosome number in the genus Senna is 2n = 28, but dysploid species like Senna tora have also been observed. Objective To understand the dynamics of these TRs and their impact on S. tora dysploidization. Methods We performed a comparative fluorescence in situ hybridization (FISH) analysis among nine closely related Senna species and compared the chromosomal distribution of these repeats from a cytotaxonomic perspective by using the ITS1-5.8S-ITS2 sequence to infer phylogenetic relationships. Results Of the nine S. tora TRs, two did not show any FISH signal whereas seven TRs showed similar and contrasting patterns to other Senna species. StoTR01_86, which was localized in the pericentromeric regions in all S. tora, but not at the nucleolar organizer region (NOR) site, was colocalized at the NOR site in all species except in S. siamea. StoTR02_7_tel was mostly localized at chromosome termini, but some species had an interstitial telomeric repeat in a few chromosomes. StoTR05_180 was distributed in the subtelomeric region in most species and was highly amplified in the pericentromeric region in some species. StoTR06_159 was either absent or colocalized in the NOR site in some species, and StoIGS_463, which was localized at the NOR site in S. tora, was either absent or localized at the subtelomeric or pericentromeric regions in other species. Conclusions These data suggest that TRs play important roles in S. tora dysploidy and suggest the involvement of 45S rDNA intergenic spacers in “carrying” repeats during genome reshuffling.

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Cytogenetical analyses in three fish species of the genus Pimelodus(Siluriformes: Pimelodidae) from rio São Francisco: considerations about the karyotypical evolution in the genus

Neotropical Ichthyology ◽

10.1590/s1679-62252005000200006 ◽

2005 ◽

Vol 3 (2) ◽

pp. 285-290 ◽

Cited By ~ 25

Author(s):

Caroline Garcia ◽

Orlando Moreira Filho

Keyword(s):

Chromosome Pair ◽

Chromosomal Rearrangements ◽

Nucleolar Organizer ◽

Differential Staining ◽

Nucleolar Organizer Regions ◽

C Banding ◽

Heteromorphic Sex Chromosomes ◽

Chromosomal Markers ◽

Staining Techniques ◽

Species Specific

Karyotypes and other chromosomal markers were investigated in three species of the catfish genus Pimelodus, namely P. fur, P. maculatus and Pimelodus sp., from municipality of Três Marias, Minas Gerais, Brazil, using differential staining techniques (C-banding, Silver nitrate and CMA3 staining). The diploid chromosome number was 2n = 56 in P. maculatus and Pimelodus sp., while in P. fur 2n = 54. The karyotype of P. fur consisted in 32M + 8SM + 6ST + 8A with fundamental number (NF) of 100, that of P. maculatus 32M + 12SM + 12A with NF = 112, and that of Pimelodus sp. had 32M + 12Sm + 6ST + 6A with NF = 106.The nucleolar organizer regions (NORs) in all three species were invariably detected in telomeres of longer arm of the 20th chromosome pair. These sites were also positive after CMA3 and C-banding. No heteromorphic sex chromosomes were detected and C-banding pattern was species specific. Inferences about the karyotype differentiation in Pimelodus and putative chromosomal rearrangements are hypohesized.

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Chromosomal variability in the wild ornamental species of Symphysodon (Perciformes: Cichlidae) from Amazon

Neotropical Ichthyology ◽

10.1590/s1679-62252008000200005 ◽

2008 ◽

Vol 6 (2) ◽

pp. 181-190 ◽

Cited By ~ 11

Author(s):

Débora R. Mesquita ◽

Jorge I. R. Porto ◽

Eliana Feldberg

Keyword(s):

Chromosomal Rearrangements ◽

Nucleolar Organizer ◽

Pericentromeric Region ◽

Nucleolar Organizer Regions ◽

Large Variability ◽

Heterochromatic Block ◽

Chromosomal Heteromorphism ◽

Chromosomal Variability ◽

In The Wild ◽

Ornamental Species

Cytogenetic studies were conducted on three discus species which inhabit the Amazon in Brazil: Symphysodon haraldi from Manacapuru, S. aequifasciatus from Tefé and S. discus from Barcelos. All individuals showed 2n=60 chromosomes, most of them biarmed. No sexual chromosomal heteromorphism was verified. However, different karyotypic formulae, owing to the presence of subtelocentric chromosomes, were verified for S. aequifasciatus and S. discus. One of the karyotypic formulae from S. aequifasciatus (cytotype 2) differs from the others, due to one of the homologues in the first chromosome pair being significantly larger than the other. A large variability was observed toward the nucleolar organizer regions (NOR) of S. haraldi and S. aequifasciatus. Although the number of silver-stained blocks varied from 2 to 5, confirming different NOR patterns, at least seven homologue pairs were involved with NORs. In S. discus only two marks were observed, however two chromosome pairs were involved, characterizing a multiple NOR system for the three species. The heterochromatic blocks were mainly located in the pericentromeric region of all chromosomes but, in some of them, they are also located in the proximal regions, both in the short and long arms. Moreover, in the cytotype 2 from S. aequifasciatus, an interstitial heterochromatic block was observed on the long arm of the largest homologue of the first pair. A direct comparison of karyotypes from more related genera (Heros, Uaru, Mesonauta and Pterophyllum), makes it clear that a succession of chromosomal rearrangements, mainly pericentric inversions, translocations and fissions/fusions occurred resulting in the present diploid number and intraspecific karyological variability found in Symphysodon.

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Polytene chromosomes of Simulium (Psaroniocompsa) daltanhani (Diptera: Simuliidae) from Central Amazonia, Brazil

Zootaxa ◽

10.11646/zootaxa.1676.1.6 ◽

2008 ◽

Vol 1676 (1) ◽

pp. 57 ◽

Cited By ~ 2

Author(s):

NEUSA HAMADA ◽

ELENY DA SILVA PEREIRA ◽

PETER H. ADLER

Keyword(s):

Banding Pattern ◽

Polytene Chromosomes ◽

Nucleolar Organizer ◽

Species Group ◽

Chromosomal Complement ◽

Central Amazonia ◽

Similar Banding Pattern ◽

Chromosome I

Last-instar larvae of Simulium (Psaroniocompsa) daltanhani Hamada and Adler from a stream in Central Amazonia were analyzed cytologically by mapping their polytene chromosomes. Simulium daltanhani has the nucleolar organizer in the short arm of chromosome I, heterogametic females, and an absence of autosomal polymorphisms. The chromosomes carry multiple rearrangements relative to other analyzed members of the S. quadrifidum species group in the subgenus Psaroniocompsa. One-third of the chromosomal complement is rearranged relative to the sequence of S. ulyssesi, the species with the most similar banding pattern among studied members of the S. quadrifidum group.

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Cytogenetic characterization of a genetic sexing strain in Ceratitis capitata

Genome ◽

10.1139/g91-092 ◽

1991 ◽

Vol 34 (4) ◽

pp. 606-611 ◽

Cited By ~ 8

Author(s):

A. Zacharopoulou ◽

M. E. Riva ◽

A. Malacrida ◽

G. Gasperi

Keyword(s):

Y Chromosome ◽

Ceratitis Capitata ◽

Chromosomal Rearrangements ◽

Polytene Chromosomes ◽

Chromosome 2 ◽

Genetic Sexing ◽

Cytogenetic Characterization ◽

Cytological Characteristics ◽

Genetic Sexing Strain

A genetic sexing strain of Ceratitis capitata, carrying a null mutation for ADH activity linked to the Y chromosome, was analysed cytogenetically. In addition to an insertion of a large part of the Y chromosome into chromosome 2, this strain carries two other chromosomal rearrangements, a deletion in the second chromosome and a reciprocal translocation involving chromosomes 2 and 4. The progeny of the T(2;4) translocation heterozygote with unbalanced chromosome constitution can survive up to the larval and (or) to the adult stage. These cytological characteristics are discussed in relation to the genetic sexing behaviour of this line.Key words: Ceratitis capitata, polytene chromosomes, genetic sexing.

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Physicochemical characteristics of the Dombrovska pit lake (Ukraine) formed in an opencast potassium salt mine and the genome response of Chironomus salinarius Kieffer (Chironomidae, Diptera) to these conditions

Environmental Science and Pollution Research ◽

10.1007/s11356-020-10465-0 ◽

2020 ◽

Vol 28 (1) ◽

pp. 446-458

Author(s):

Paraskeva Michailova ◽

Ewa Szarek-Gwiazda ◽

Andrzej Kownacki

Keyword(s):

Potassium Salt ◽

Major Ions ◽

Genome Instability ◽

Polytene Chromosomes ◽

Benthic Fauna ◽

Nucleolar Organizer ◽

Salt Mine ◽

Pit Lake ◽

Functional Changes ◽

Chironomus Salinarius

AbstractThis study focuses on the Dombrovska pit lake, near the city of Kalush in Ukraine, which is a former potassium salt mine filled with brine and freshwater. The water level is still increasing and as a result the salinity is decreasing. We analyzed the benthic fauna communities and the genome instability by assessing the rearrangements in the polytene chromosomes of Chironomus salinarius and the physicochemical parameters of the near-bottom water (pH, conductivity, mineralization, major ions, NO3−, NH4+, metals Cd, Pb, Cu, Mn, and Fe) and sediment (pH, organic matter and metals Cd, Pb, Cu, Zn, Mn, and Fe) at four sites. The water mineralization ranged from 17.3 to 26.2 g dm−3 which are classified as mesohaline and polyhaline waters, respectively. The biodiversity of the benthic fauna was low, and the dominant species was C. salinarius. The density of C. salinarius varied spatially and changed from 637 ind./m2 at a depth of 5 m to 8167 ind./m2 at a depth of 2.5 m. The genome instability was analyzed by examining the structural and functional changes in the salivary gland chromosomes of C. salinarius. The exposure of C. salinarius damaged the chromosomes and the activities of key structures, such as the Balbiani ring and nucleolar organizer, were partially or completely suppressed.

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Karyotypic Differences Between Two Species of Pomatoceros, P. Triqueter and P. Lamarckii (Polychaeta: Serpulidae)

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315400044362 ◽

1998 ◽

Vol 78 (4) ◽

pp. 1113-1126 ◽

Cited By ~ 6

Author(s):

D.R. Dixon ◽

P.L. Pascoe ◽

L.R.J. Dixon

Keyword(s):

Chromosomal Rearrangements ◽

Organizer Region ◽

Nucleolar Organizer Region ◽

Nucleolar Organizer ◽

Species Variation ◽

Species Status ◽

Separate Species ◽

Polychaete Species ◽

Species Integrity ◽

South West England

Consistent with most other closely-related polychaete species which have been analysed cytogenetically to-date, Pomatoceros triqueter and P. lamarckii share an identical chromosome number (2n=24) and have a number of other karyotypic features in common. However, commensurate with their separate species status, their karyotypes differ at least in four chromosome positions as a result of structural chromosomal rearrangements. With a rDNA probe using the FISH technique, we have been able to demonstrate that the nucleolar organizer region (NOR) occurs at the same site on the same pair of chromosomes in the two species, which indicates that an inversion event is unlikely to have been the cause of the species variation in this particular case. Taken together, these karyotypic differences may be indicative of a chromosomal barrier to the formation of fertile offspring; an important feature for maintaining species integrity where the two forms occur sympatrically, such as in parts of south-west England.

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Three-dimensional organization of Drosophila melanogaster interphase nuclei. II. Chromosome spatial organization and gene regulation.

The Journal of Cell Biology ◽

10.1083/jcb.104.6.1471 ◽

1987 ◽

Vol 104 (6) ◽

pp. 1471-1483 ◽

Cited By ~ 76

Author(s):

M Hochstrasser ◽

J W Sedat

Keyword(s):

Gene Regulation ◽

Drosophila Melanogaster ◽

Nuclear Envelope ◽

Spatial Organization ◽

Polytene Chromosomes ◽

Three Dimensional ◽

Nucleolar Organizer ◽

Cell Types ◽

Functional Changes ◽

Specific Subset

In the preceding article we compared the general organization of polytene chromosomes in four different Drosophila melanogaster cell types. Here we describe experiments aimed at testing for a potential role of three-dimensional chromosome folding and positioning in modulating gene expression and examining specific chromosome interactions with different nuclear structures. By charting the configurations of salivary gland chromosomes as the cells undergo functional changes, it is shown that loci are not repositioned within the nucleus when the pattern of transcription changes. Heterologous loci show no evidence of specific physical interactions with one another in any of the cell types. However, a specific subset of chromosomal loci is attached to the nuclear envelope, and this subset is extremely similar in at least two tissues. In contrast, no specific interactions between any locus and the nucleolus are found, but the base of the X chromosome, containing the nucleolar organizer, is closely linked to this organelle. These results are used to evaluate models of gene regulation that involve the specific intranuclear positioning of gene sequences. Finally, data are presented on an unusual class of nuclear envelope structures, filled with large, electron-dense particles, that are usually associated with chromosomes.

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NORs on human acrocentric chromosome p-arms are active by default and can associate with nucleoli independently of rDNA

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2001812117 ◽

2020 ◽

Vol 117 (19) ◽

pp. 10368-10377

Author(s):

Marjolein van Sluis ◽

Chelly van Vuuren ◽

Hazel Mangan ◽

Brian McStay

Keyword(s):

Cell Lines ◽

Ribosome Biogenesis ◽

Chromosomal Rearrangements ◽

Three Dimensional ◽

Nucleolar Organizer ◽

Factor Loading ◽

Interindividual Variation ◽

Nucleolar Organizer Regions ◽

Metaphase Chromosomes ◽

Acrocentric Chromosomes

Nucleoli, the sites of ribosome biogenesis and the largest structures in human nuclei, form around nucleolar organizer regions (NORs) comprising ribosomal DNA (rDNA) arrays. NORs are located on the p-arms of the five human acrocentric chromosomes. Defining the rules of engagement between these p-arms and nucleoli takes on added significance as describing the three-dimensional organization of the human genome represents a major research goal. Here we used fluorescent in situ hybridization (FISH) and immuno-FISH on metaphase chromosomes from karyotypically normal primary and hTERT-immortalized human cell lines to catalog NORs in terms of their relative rDNA content and activity status. We demonstrate that a proportion of acrocentric p-arms in cell lines and from normal human donors have no detectable rDNA. Surprisingly, we found that all NORs with detectable rDNA are active, as defined by upstream binding factor loading. We determined the nucleolar association status of all NORs during interphase, and found that nucleolar association of acrocentric p-arms can occur independently of rDNA content, suggesting that sequences elsewhere on these chromosome arms drive nucleolar association. In established cancer lines, we characterize a variety of chromosomal rearrangements involving acrocentric p-arms and observe silent, rDNA-containing NORs that are dissociated from nucleoli. In conclusion, our findings indicate that within human nuclei, positioning of all 10 acrocentric chromosomes is dictated by nucleolar association. Furthermore, these nucleolar associations are buffered against interindividual variation in the distribution of rDNA.

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Polytene chromosomes of an Indian Himalayan black fly Simulium (Nevermannia) praelargum (Diptera: Simuliidae)

Current Zoology ◽

10.1093/czoolo/56.4.437 ◽

2010 ◽

Vol 56 (4) ◽

pp. 437-444 ◽

Cited By ~ 1

Author(s):

Willie Henry ◽

Subrata Kumar Dey ◽

Rakesh Varma ◽

Sachin Thapa ◽

William S Procunier

Keyword(s):

High Resolution ◽

Polytene Chromosome ◽

Polytene Chromosomes ◽

Nucleolar Organizer ◽

Metacentric Chromosome ◽

Double Bubble ◽

High Quality ◽

Chromosomal Markers ◽

Total Complement ◽

Chromosome Maps

Abstract High quality polytene chromosome maps (n=3) of a Himalayan Simuliid Simulium praelargum Datta, 1973 are presented and represent the first cytological description of a taxon found in the feuerborni group, subgenus Nevermannia. Polytene chromosomes one (I) and two (II) are metacentric, chromosome three (III) is submetacentric with the length of each chromosome occupying 37.25 %, 31.36 % and 31.34 % of the total complement length, respectively. Typical simuliid diagnostic intergeneric chromosomal markers are found within the polytene complement of this species. The nucleolar organizer (N.O.) is found at the base of the short arm of chromosome one (IS), the Ring of Balbiani (R.B.), double bubble (D.B.) and triad occur in the short arm of chromosome two (IIS), the Parabalbiani Ring (P.B.) and grey band (gb) occur in the long arm of chromosome two (IIL) and the Blister (BL) and Capsule (Ca) occur in the short arm of chromosome three (IIIS).Terminal bands at the end of IIIS are heterochromatinized and present atypically with respect to other simuliid fauna. Populations studied so far are unique among the Simuliidae in that they exhibit chromosome structural monomorphism. These high resolution polytene chromosome maps will form the basis for future cytological characterization and phylogenetic comparisons amongst members of the feuerborni group.

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