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Chromosomal organization of the ribosomal RNA genes in the genus Chironomus (Diptera, Chironomidae).

Gunderina L, Golygina V, Broshkov A - Comp Cytogenet (2015)

Bottom Line: In the majority of studied species the location of rDNA sites coincided with the sites where active NORs (nucleolus organizer regions) were found.NORs were found in all chromosomal arms of species from the subgenus Chironomus with one of them always located on arm G.On the other hand, no hybridization sites were found on arm G in four studied species from the subgenus Camptochironomus.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Cytology and Genetics SB RAS, Academician Lavrentiev avenue 10, Novosibirsk, 630090, Russia.

ABSTRACT
Chromosomal localization of ribosomal RNA coding genes has been studied by using FISH (fluorescence in situ hybridization) in 21 species from the genus Chironomus Meigen, 1803. Analysis of the data has shown intra- and interspecific variation in number and location of 5.8S rDNA hybridization sites in 17 species from the subgenus Chironomus and 4 species from the subgenus Camptochironomus Kieffer, 1914. In the majority of studied species the location of rDNA sites coincided with the sites where active NORs (nucleolus organizer regions) were found. The number of hybridization sites in karyotypes of studied chironomids varied from 1 to 6. More than half of the species possessed only one NOR (12 out of 21). Two rDNA hybridization sites were found in karyotypes of five species, three - in two species, and five and six sites - in one species each. NORs were found in all chromosomal arms of species from the subgenus Chironomus with one of them always located on arm G. On the other hand, no hybridization sites were found on arm G in four studied species from the subgenus Camptochironomus. Two species from the subgenus Chironomus - Chironomusbalatonicus Devai, Wuelker & Scholl, 1983 and Chironomus "annularius" sensu Strenzke, 1959 - showed intraspecific variability in the number of hybridization signals. Possible mechanisms of origin of variability in number and location of rRNA genes in the karyotypes of species from the genus Chironomus are discussed.

No MeSH data available.


Related in: MedlinePlus

FISH of rDNA probes on polytene chromosomes of species from the subgenus Camptochironomus. a–cChironomustentans, where b and c specimens with heterozygous inversions in arm B that change the position of NOR in one of the homologues dCamptochironomusdilutus; eCamptochironomuspallidivittatusfCamptochironomussetivalva. Letters designate chromosomal arms. Bar = 10 µm.
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Figure 6: FISH of rDNA probes on polytene chromosomes of species from the subgenus Camptochironomus. a–cChironomustentans, where b and c specimens with heterozygous inversions in arm B that change the position of NOR in one of the homologues dCamptochironomusdilutus; eCamptochironomuspallidivittatusfCamptochironomussetivalva. Letters designate chromosomal arms. Bar = 10 µm.

Mentions: Karyotypes of most Chironomus species studied in this work have four polytene chromosomes, which corresponds to the haploid chromosome set n = 4 (Figs 1–4). The only exception is Chironomusnudiventris that have three chromosomes in its haploid set. The chromosome number in the karyotype of this species reduced via fusion of arms G (chromosome IV) and E (chromosome III, EF) to form the joint chromosome GEF (Fig. 3d, Table 3).


Chromosomal organization of the ribosomal RNA genes in the genus Chironomus (Diptera, Chironomidae).

Gunderina L, Golygina V, Broshkov A - Comp Cytogenet (2015)

FISH of rDNA probes on polytene chromosomes of species from the subgenus Camptochironomus. a–cChironomustentans, where b and c specimens with heterozygous inversions in arm B that change the position of NOR in one of the homologues dCamptochironomusdilutus; eCamptochironomuspallidivittatusfCamptochironomussetivalva. Letters designate chromosomal arms. Bar = 10 µm.
© Copyright Policy - creative-commons-attribution
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4488967&req=5

Figure 6: FISH of rDNA probes on polytene chromosomes of species from the subgenus Camptochironomus. a–cChironomustentans, where b and c specimens with heterozygous inversions in arm B that change the position of NOR in one of the homologues dCamptochironomusdilutus; eCamptochironomuspallidivittatusfCamptochironomussetivalva. Letters designate chromosomal arms. Bar = 10 µm.
Mentions: Karyotypes of most Chironomus species studied in this work have four polytene chromosomes, which corresponds to the haploid chromosome set n = 4 (Figs 1–4). The only exception is Chironomusnudiventris that have three chromosomes in its haploid set. The chromosome number in the karyotype of this species reduced via fusion of arms G (chromosome IV) and E (chromosome III, EF) to form the joint chromosome GEF (Fig. 3d, Table 3).

Bottom Line: In the majority of studied species the location of rDNA sites coincided with the sites where active NORs (nucleolus organizer regions) were found.NORs were found in all chromosomal arms of species from the subgenus Chironomus with one of them always located on arm G.On the other hand, no hybridization sites were found on arm G in four studied species from the subgenus Camptochironomus.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Cytology and Genetics SB RAS, Academician Lavrentiev avenue 10, Novosibirsk, 630090, Russia.

ABSTRACT
Chromosomal localization of ribosomal RNA coding genes has been studied by using FISH (fluorescence in situ hybridization) in 21 species from the genus Chironomus Meigen, 1803. Analysis of the data has shown intra- and interspecific variation in number and location of 5.8S rDNA hybridization sites in 17 species from the subgenus Chironomus and 4 species from the subgenus Camptochironomus Kieffer, 1914. In the majority of studied species the location of rDNA sites coincided with the sites where active NORs (nucleolus organizer regions) were found. The number of hybridization sites in karyotypes of studied chironomids varied from 1 to 6. More than half of the species possessed only one NOR (12 out of 21). Two rDNA hybridization sites were found in karyotypes of five species, three - in two species, and five and six sites - in one species each. NORs were found in all chromosomal arms of species from the subgenus Chironomus with one of them always located on arm G. On the other hand, no hybridization sites were found on arm G in four studied species from the subgenus Camptochironomus. Two species from the subgenus Chironomus - Chironomusbalatonicus Devai, Wuelker & Scholl, 1983 and Chironomus "annularius" sensu Strenzke, 1959 - showed intraspecific variability in the number of hybridization signals. Possible mechanisms of origin of variability in number and location of rRNA genes in the karyotypes of species from the genus Chironomus are discussed.

No MeSH data available.


Related in: MedlinePlus