Molecular cytogenetic characterization of the Amazon River dolphin Inia geoffrensis

Classical and molecular cytogenetic (18S rDNA, telomeric sequence, and LINE-1 retrotransposon probes) studies were carried out to contribute to an understanding of the organization of repeated DNA elements in the Amazon River dolphin (boto, Inia geoffrensis). Twenty-seven specimens were examined, ea...

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Bibliographic Details
Published in:	Genetica Vol. 140; no. 7-9; pp. 307 - 315
Main Authors:	Bonifácio, Heidi L, da Silva, Vera M. F, Martin, Anthony R, Feldberg, Eliana
Format:	Journal Article
Language:	English
Published:	Dordrecht Springer-Verlag 01-09-2012 Springer Netherlands Springer Nature B.V
Subjects:	Animal Genetics and Genomics Animals Aquatic mammals Biomedical and Life Sciences Brackish Cetacea Chromosomes Cytogenetics DNA, Ribosomal - genetics dolphins Dolphins - genetics Euchromatin - genetics Euchromatin - metabolism Evolutionary Biology heterochromatin Human Genetics Inia geoffrensis Karyotypes Karyotyping Life Sciences Marine Microbial Genetics and Genomics nucleolus organizer region Nucleolus Organizer Region - genetics Plant Genetics and Genomics ribosomal DNA Rivers telomeres X chromosome Amazon River South America, Amazon R FISH 18S rDNA Heterochromatin polymorphism Boto LINE-1 retrotransposon
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Summary:	Classical and molecular cytogenetic (18S rDNA, telomeric sequence, and LINE-1 retrotransposon probes) studies were carried out to contribute to an understanding of the organization of repeated DNA elements in the Amazon River dolphin (boto, Inia geoffrensis). Twenty-seven specimens were examined, each presenting 2n = 44 chromosomes, the karyotype formula 12m + 14sm + 6st + 10t + XX/XY, and fundamental number (FN) = 74. C-positive heterochromatin was observed in terminal and interstitial positions, with the occurrence of polymorphism. Interstitial telomeric sequences were not observed. The nucleolar organizer region (NOR) was located at a single site on a smallest autosomal pair. LINE-1 was preferentially distributed in the euchromatin regions, with the greatest accumulation on the X chromosome. Although the karyotype structure in cetaceans is considered to be conserved, the boto karyotype demonstrated significant variations in its formula, heterochromatin distribution, and the location of the NOR compared to other cetacean species. These results contribute to knowledge of the chromosome organization in boto and to a better understanding of karyoevolution in cetaceans.
Bibliography:	http://dx.doi.org/10.1007/s10709-012-9680-7 ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	0016-6707 1573-6857
DOI:	10.1007/s10709-012-9680-7