Transcription of a protein-coding gene on B chromosomes of the Siberian roe deer (Capreolus pygargus)

• Published in: BMC biology 2013-08, Vol.11 (1), p.90-90, Article 90
• Main Authors: Trifonov, Vladimir A, Dementyeva, Polina V, Larkin, Denis M, O'Brien, Patricia C M, Perelman, Polina L, Yang, Fengtang, Ferguson-Smith, Malcolm A, Graphodatsky, Alexander S
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Analysis; Animals; Artificial chromosomes; Base Sequence; Capreolus pygargus; Cattle; Chromosome Mapping; Chromosomes; Chromosomes, Artificial, Bacterial - genetics; Chromosomes, Mammalian - genetics; Cloning; Cloning, Molecular; Comparative analysis; Deer; Deer - genetics; Deoxyribonucleic acid; DNA; DNA Copy Number Variations - genetics; Experiments; Female; Gene Dosage - genetics; Gene Library; Genes; Genetic aspects; Genetic transcription; Genomes; Genomics; Hybridization; In Situ Hybridization, Fluorescence; Male; Medical equipment and supplies industry; Medical test kit industry; Mitochondrial DNA; Molecular Sequence Data; Nucleotidyltransferases - genetics; Open Reading Frames - genetics; Physiological aspects; Polymerase Chain Reaction; Proteins; Ribosomal DNA; Sequence Analysis, DNA; Siberia; Species Specificity; Transcription, Genetic; Veterinary medicine
• ISSN: 1741-7007; 1741-7007
• DOI: 10.1186/1741-7007-11-90

Most eukaryotic species represent stable karyotypes with a particular diploid number. B chromosomes are additional to standard karyotypes and may vary in size, number and morphology even between cells of the same individual. For many years it was generally believed that B chromosomes found in some plant, animal and fungi species lacked active genes. Recently, molecular cytogenetic studies showed the presence of additional copies of protein-coding genes on B chromosomes. However, the transcriptional activity of these genes remained elusive. We studied karyotypes of the Siberian roe deer (Capreolus pygargus) that possess up to 14 B chromosomes to investigate the presence and expression of genes on supernumerary chromosomes. Here, we describe a 2 Mbp region homologous to cattle chromosome 3 and containing TNNI3K (partial), FPGT, LRRIQ3 and a large gene-sparse segment on B chromosomes of the Siberian roe deer. The presence of the copy of the autosomal region was demonstrated by B-specific cDNA analysis, PCR assisted mapping, cattle bacterial artificial chromosome (BAC) clone localization and quantitative polymerase chain reaction (qPCR). By comparative analysis of B-specific and non-B chromosomal sequences we discovered some B chromosome-specific mutations in protein-coding genes, which further enabled the detection of a FPGT-TNNI3K transcript expressed from duplicated genes located on B chromosomes in roe deer fibroblasts. Discovery of a large autosomal segment in all B chromosomes of the Siberian roe deer further corroborates the view of an autosomal origin for these elements. Detection of a B-derived transcript in fibroblasts implies that the protein coding sequences located on Bs are not fully inactivated. The origin, evolution and effect on host of B chromosomal genes seem to be similar to autosomal segmental duplications, which reinforces the view that supernumerary chromosomal elements might play an important role in genome evolution.