Limits...
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 Chironomus with one NOR in karyotype. aChironomusborokensisbChironomusdorsaliscChironomusentisdChironomuslacunariuseChironomusluridusfChironomusnuditarsisgChironomusmelanescenshChironomusplumosusiChironomussororiusjChironomusriparius. Letters designate chromosomal arms. Bar = 10 µm.
© Copyright Policy - creative-commons-attribution
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4488967&req=5

Figure 2: FISH of rDNA probes on polytene chromosomes of species from the subgenus Chironomus with one NOR in karyotype. aChironomusborokensisbChironomusdorsaliscChironomusentisdChironomuslacunariuseChironomusluridusfChironomusnuditarsisgChironomusmelanescenshChironomusplumosusiChironomussororiusjChironomusriparius. Letters designate chromosomal arms. Bar = 10 µm.

Mentions: The species belonging to the subgenera Chironomus and Camptochironomus are similar in the number of rDNA loci in their karyotypes (one or two NORs) but differ considerably in their chromosomal positions. In species from the subgenus Chironomus NORs have been found in all chromosomal arms, whereas in species from the subgenus Camptochironomus NORs have been detected in arms A, B, C and D only. Unlike species belonging to the subgenus Chironomus with obligatory presence of one of the NORs in arm G (Figs 2–3), no NOR in this arm has been detected in all four Camptochironomus species (Fig. 4). In Camptochironomus NOR is most frequently found in arm B, being observed in three of the four examined species, namely, Camptochironomussetivalva, Camptochironomusdilutus, and Chironomustentans. In the Camptochironomussetivalva karyotype it is the only one NOR found, while Camptochironomusdilutus and Chironomustentans carried one additional NOR in arms C and D, respectively. Only one NOR has been found in arm A of Camptochironomuspallidivittatus (Fig. 4).


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 Chironomus with one NOR in karyotype. aChironomusborokensisbChironomusdorsaliscChironomusentisdChironomuslacunariuseChironomusluridusfChironomusnuditarsisgChironomusmelanescenshChironomusplumosusiChironomussororiusjChironomusriparius. 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 2: FISH of rDNA probes on polytene chromosomes of species from the subgenus Chironomus with one NOR in karyotype. aChironomusborokensisbChironomusdorsaliscChironomusentisdChironomuslacunariuseChironomusluridusfChironomusnuditarsisgChironomusmelanescenshChironomusplumosusiChironomussororiusjChironomusriparius. Letters designate chromosomal arms. Bar = 10 µm.
Mentions: The species belonging to the subgenera Chironomus and Camptochironomus are similar in the number of rDNA loci in their karyotypes (one or two NORs) but differ considerably in their chromosomal positions. In species from the subgenus Chironomus NORs have been found in all chromosomal arms, whereas in species from the subgenus Camptochironomus NORs have been detected in arms A, B, C and D only. Unlike species belonging to the subgenus Chironomus with obligatory presence of one of the NORs in arm G (Figs 2–3), no NOR in this arm has been detected in all four Camptochironomus species (Fig. 4). In Camptochironomus NOR is most frequently found in arm B, being observed in three of the four examined species, namely, Camptochironomussetivalva, Camptochironomusdilutus, and Chironomustentans. In the Camptochironomussetivalva karyotype it is the only one NOR found, while Camptochironomusdilutus and Chironomustentans carried one additional NOR in arms C and D, respectively. Only one NOR has been found in arm A of Camptochironomuspallidivittatus (Fig. 4).

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