B chromosome ancestry revealed by histone genes in the migratory locust
- 303 Downloads
In addition to the standard set of chromosomes (A), about 15% of eukaryote genomes carry B chromosomes. In most cases, B chromosomes behave as genomic parasites being detrimental for the individuals carrying them and prospering in natural populations because of transmission advantages (drive). B chromosomes are mostly made up of repetitive DNA sequences, especially ribosomal DNA (rDNA), satellite DNA and mobile elements. In only two cases have B chromosomes been shown to carry protein-coding genes. Although some B chromosomes seem to have derived from interspecific hybridisation, the most likely source of B chromosomes is the host genome itself, but the specific A chromosome being the B ancestor has not been identified in any B-containing species. Here, we provide strong evidence for B chromosome ancestry in the migratory locust, based on the location of genes for the H3 and H4 histones in the B chromosome and a single A chromosome pair (i.e. the eighth in order of decreasing size). The high DNA sequence similarity of A and B chromosome H3–H4 genes supports B-origin from chromosome 8. The higher variation shown by B sequences, compared to A sequences, suggests that B chromosome sequences are most likely inactive and thus less subjected to purifying selection. Estimates of time of divergence for histone genes from A and B chromosomes suggest that B chromosomes are quite old (>750,000 years), showing the B-chromosome ability to persist in natural populations for long periods of time.
KeywordsHistone Gene Grasshopper Species Putative Amino Acid Sequence Migratory Locust Similar Substitution Rate
We thank Tatiana López for technical assistance and David Martinez for English corrections. This study was supported by grants from the Spanish Ministerio de Ciencia y Tecnología (CGL2006-06307) and Plan Andaluz de Investigación (CVI-1664). This research was partially performed by FEDER funds.
- Cabrero J, Viseras E, Camacho JPM (1984) The B chromosomes of Locusta migratoria.1. Detection of negative correlation between mean chiasma frequency and the rate of accumulation of the Bs. A reanalysis of the available data about the transmission of these B chromosomes. Genetica 64:155–164CrossRefGoogle Scholar
- Camacho JPM, Cabrero J, Viseras E, López-León MD, Navas-Castillo J, Alché JD (1991) G-Banding in two species of grasshopper and its relationship to C, N, and fluorescence banding techniques. Genome 34:638–643Google Scholar
- Hall TA (1999) BioEdit: a user-friendly biological sequence alignment editor and analysis program for Windows 95/98/NT. Nucl Acids Symp Ser 41:95–98Google Scholar
- Hsiang W (1958) Cytological studies on migratory locust hybrid, Locusta migratoria migratoria L. X Locusta migratoria manilensis Meyen. Acta Zool Sin 10:53–59Google Scholar
- Jago ND (1983) The breakup of Pangaea and prediction of numbers of subfamily elements, living and extinct, in Acridoidea. Proc Pan Am Acrid Soc 2:139–162Google Scholar
- Li W-H (1997) Molecular evolution. Sinauer, SunderlandGoogle Scholar
- Santos JL (1980) Variación de la heterocromatina constitutiva en el cariotipo de los Acridoidea y su efecto en el comportamiento cromosómico en meiosis. Ph.D. thesis, Universidad Complutense de Madrid, SpainGoogle Scholar
- Teruel M (2009) Origen, expresión y efectos fenotípicos de un parásito genómico. PhD. Thesis, Universidad de Granada, SpainGoogle Scholar
- Viseras E, Camacho JPM, Cano MI, Santos JL (1990) Relationship between mitotic instability and accumulation of B chromosomes in males and females of Locusta migratoria. Genome 33:23–29Google Scholar
- White TJ, BrunsT LS, Taylor J (1990) Amplification and direct sequencing of fungal ribosomal RNA for phylogenetics. In: Innis MA, Gelfand DH, Sninsky JJ, White TJ (eds) PCR protocols: a guide to methods and amplications. Academic, San Diego, pp 315–322Google Scholar