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B-chromosome ribosomal DNA is functional in the grasshopper Eyprepocnemis plorans.
PLoS One. 2012; 7(5):e36600.Plos

Abstract

B-chromosomes are frequently argued to be genetically inert elements, but activity for some particular genes has been reported, especially for ribosomal RNA (rRNA) genes whose expression can easily be detected at the cytological level by the visualization of their phenotypic expression, i.e., the nucleolus. The B(24) chromosome in the grasshopper Eyprepocnemis plorans frequently shows a nucleolus attached to it during meiotic prophase I. Here we show the presence of rRNA transcripts that unequivocally came from the B(24) chromosome. To detect these transcripts, we designed primers specifically anchoring at the ITS-2 region, so that the reverse primer was complementary to the B chromosome DNA sequence including a differential adenine insertion being absent in the ITS2 of A chromosomes. PCR analysis carried out on genomic DNA showed amplification in B-carrying males but not in B-lacking ones. PCR analyses performed on complementary DNA showed amplification in about half of B-carrying males. Joint cytological and molecular analysis performed on 34 B-carrying males showed a close correspondence between the presence of B-specific transcripts and of nucleoli attached to the B chromosome. In addition, the molecular analysis revealed activity of the B chromosome rDNA in 10 out of the 13 B-carrying females analysed. Our results suggest that the nucleoli attached to B chromosomes are actively formed by expression of the rDNA carried by them, and not by recruitment of nucleolar materials formed in A chromosome nucleolar organizing regions. Therefore, B-chromosome rDNA in E. plorans is functional since it is actively transcribed to form the nucleolus attached to the B chromosome. This demonstrates that some heterochromatic B chromosomes can harbour functional genes.

Authors+Show Affiliations

Departamento de Genética, Universidad de Granada, Granada, Spain.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

22570730

Citation

Ruiz-Estévez, Mercedes, et al. "B-chromosome Ribosomal DNA Is Functional in the Grasshopper Eyprepocnemis Plorans." PloS One, vol. 7, no. 5, 2012, pp. e36600.
Ruiz-Estévez M, López-León MD, Cabrero J, et al. B-chromosome ribosomal DNA is functional in the grasshopper Eyprepocnemis plorans. PLoS One. 2012;7(5):e36600.
Ruiz-Estévez, M., López-León, M. D., Cabrero, J., & Camacho, J. P. (2012). B-chromosome ribosomal DNA is functional in the grasshopper Eyprepocnemis plorans. PloS One, 7(5), e36600. https://doi.org/10.1371/journal.pone.0036600
Ruiz-Estévez M, et al. B-chromosome Ribosomal DNA Is Functional in the Grasshopper Eyprepocnemis Plorans. PLoS One. 2012;7(5):e36600. PubMed PMID: 22570730.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - B-chromosome ribosomal DNA is functional in the grasshopper Eyprepocnemis plorans. AU - Ruiz-Estévez,Mercedes, AU - López-León,Ma Dolores, AU - Cabrero,Josefa, AU - Camacho,Juan Pedro M, Y1 - 2012/05/03/ PY - 2012/03/02/received PY - 2012/04/09/accepted PY - 2012/5/10/entrez PY - 2012/5/10/pubmed PY - 2013/1/25/medline SP - e36600 EP - e36600 JF - PloS one JO - PLoS One VL - 7 IS - 5 N2 - B-chromosomes are frequently argued to be genetically inert elements, but activity for some particular genes has been reported, especially for ribosomal RNA (rRNA) genes whose expression can easily be detected at the cytological level by the visualization of their phenotypic expression, i.e., the nucleolus. The B(24) chromosome in the grasshopper Eyprepocnemis plorans frequently shows a nucleolus attached to it during meiotic prophase I. Here we show the presence of rRNA transcripts that unequivocally came from the B(24) chromosome. To detect these transcripts, we designed primers specifically anchoring at the ITS-2 region, so that the reverse primer was complementary to the B chromosome DNA sequence including a differential adenine insertion being absent in the ITS2 of A chromosomes. PCR analysis carried out on genomic DNA showed amplification in B-carrying males but not in B-lacking ones. PCR analyses performed on complementary DNA showed amplification in about half of B-carrying males. Joint cytological and molecular analysis performed on 34 B-carrying males showed a close correspondence between the presence of B-specific transcripts and of nucleoli attached to the B chromosome. In addition, the molecular analysis revealed activity of the B chromosome rDNA in 10 out of the 13 B-carrying females analysed. Our results suggest that the nucleoli attached to B chromosomes are actively formed by expression of the rDNA carried by them, and not by recruitment of nucleolar materials formed in A chromosome nucleolar organizing regions. Therefore, B-chromosome rDNA in E. plorans is functional since it is actively transcribed to form the nucleolus attached to the B chromosome. This demonstrates that some heterochromatic B chromosomes can harbour functional genes. SN - 1932-6203 UR - https://www.unboundmedicine.com/medline/citation/22570730/B_chromosome_ribosomal_DNA_is_functional_in_the_grasshopper_Eyprepocnemis_plorans_ L2 - https://dx.plos.org/10.1371/journal.pone.0036600 DB - PRIME DP - Unbound Medicine ER -