Chromosomal mapping reveals a dynamic organization of the histone genes in aphids (Hemiptera: Aphididae) (original) (raw)
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Chromosome mapping of H3 and H4 histone gene clusters in 35 species of acridid grasshoppers
Chromosome Research, 2009
We analyse chromosome location of H3 and H4 histone gene clusters by fluorescence in-situ hybridization (FISH) in 35 species of Acrididae grasshoppers belonging to seven subfamilies. As in other organisms, H3 and H4 co-localized in the same chromosome region in the 11 species where double FISH was performed with the H3 and H4 DNA probes. Chromosome location of H3-H4 histone gene clusters showed high regularity in the species analysed, with all of them carrying a single H3-H4 cluster in an autosome which, in most cases, was located interstitially in the proximal chromosome third. In 17 out of the 21 species with 2n♂ = 23 acrocentric chromosomes, the H3-H4-carrying autosome was about eighth in order of decreasing size. Two of the four exceptions changed H3-H4 localization to proximal (Pezotettix giornae) or distal (Tropidopola graeca) in the eighth-sized autosome, but the remainder (the two Eyprepocnemis species) showed the H3-H4 cluster distally located in the second-sized autosome. All 14 species with 2n♂ = 17 chromosomes (including three long metacentric autosome pairs, five acrocentric autosome pairs and an acrocentric X chromosome) carried an interstitial H3-H4 cluster in the short arm of the smallest of the three long metacentric pairs. These results suggest that chromosome location of H3-H4 histone gene clusters seem to be highly conservative in Acrididae grasshoppers. The change in H3-H4 location from the acrocentric medium-sized autosome in the 2n♂ = 23 karyotype to the long metacentric autosome in the 2n♂ = 17 karyotype is most parsimoniously explained by common ancestry, i.e. by the involvement of the H3-H4-carrying acrocentric in the centric fusion that gave rise to the smallest of the three long metacentric autosomes of 2n♂ = 17 species.
Genetica, 2000
Despite the interest in aphid biology, information on chromatin organization of their holocentric chromosomes is still limited to few species. In order to fill this gap, we have performed an extensive survey on pea aphid mitotic chromosomes using both classical and molecular cytogenetic techniques. Our results after silver, CMA3 and DAPI-staining, C-banding and fluorescent in situ hybridization (FISH) using 28S rDNA and 5S rDNA as probes evidenced a tendency of repetitive DNAs to be concentrated on the X chromosomes. FISH experiments with the telomeric probe (TTAGG)n revealed bright hybridization signals on each telomere of all Acyrthosiphon pisum chromosomes. No interstitial signals were seen.
Caryologia, 2009
Heterochromation and rDNA localization in the holocentric chromosomes of the aphid Aphis fabae has been investigated at a cytological level after C-banding, Giemsa, DAPI NOR staining.C-banding technique showed that heterochromatic areas result mainly clustered on the X chromosomes but, contrary to what observed in other aphid species, in A. fabae C-positive bands are clearly distinguishable also on each autosomal chromosome pair, thus allowing the identification of homologues and a reliable reconstruction of the karyotype. Moreover, silver staining localized rDNA genes on one telomere of each X chromosome; these are the only brightly fluorescent C-positive regions revealed after CMA3 staining, whereas all other heterochromatic bands are DAPI positive. Both CMA3 and silver staining evidenced a noticeable amount of rDNA heteromorphism.