Germ line-restricted supernumerary (B) chromosomes in &lt;i&gt;Eptatretus okinoseanus&lt;/i&gt;

Kubota, Shin; Nakai, Y.; Kuro-o, Masaki; Kohno, Sei-ichi

doi:10.1159/000133345

Cited by 18 publications

(9 citation statements)

References 8 publications

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“…We previously proposed that chromosome terminus elimination, in addition to whole chromosome elimination, contributes to somatic chromosome differentiation of two hagfish species, E. stoutii and E. okinoseanus type B, on the basis of C-banding patterns (Kubota et al 1992(Kubota et al , 1994Kohno et al 1998). However, no sequence has been identified from eliminated chromosome termini to date.…”

Section: Eliminated Dna Sequences In P Shenimentioning

confidence: 99%

Whole chromosome elimination and chromosome terminus elimination both contribute to somatic differentiation in Taiwanese hagfish Paramyxine sheni

Kojima

Kobayakawa

et al. 2010

Chromosome Res

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Chromosome elimination is a process in which some chromatins are discarded from the presumptive somatic cells during early embryogenesis. Eliminated chromatins in hagfish generally consist of repetitive sequences, and they are highly heterochromatinized in germ cells. In this study, we characterized four novel eliminated DNA families, EEPs1-4, from the Taiwanese hagfish Paramyxine sheni. Sequences of these four elements occupied 20-27% of eliminated DNA in total, and each family was arranged mainly in tandem in the germline genome with high copy numbers. Although most of these elements were eliminated, a minor fraction remained in somatic cells. Some eliminated DNA families are shared as eliminated sequences between Eptatretidae and Myxinidae. Fluorescence in situ hybridization (FISH) of these elements showed that not only heterochromatic chromosomes but also both ends of euchromatic chromosomes in germ cells are absent in somatic cells of P. sheni. It strongly suggests that chromosome terminus elimination, in addition to whole chromosome elimination, contributes to somatic chromosome differentiation. Telomere-FISH further showed that chromosome fragmentation and the subsequent de novo addition of telomeric repeats are the likely mechanisms underlying chromosome terminus elimination. These characteristics make it indispensable to study the evolution and mechanisms underlying chromosome elimination in hagfish.

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Section: Eliminated Dna Sequences In P Shenimentioning

confidence: 99%

Whole chromosome elimination and chromosome terminus elimination both contribute to somatic differentiation in Taiwanese hagfish Paramyxine sheni

Kojima

Kobayakawa

et al. 2010

Chromosome Res

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“…Subsequent investigations revealed that chromosome elimination (chromatin diminution) also occurs in six other species of hagfish, namely, Eptatretus stoutii, Eptatretus okinoseanus, Eptatretus cirrhatus, Paramyxine atami, Myxine glutinosa and Myxine garmani (Nakai et al 1991(Nakai et al , 1995. E. okinoseanus can be divided into two subtypes with respect to the amount and distribution of C-band-positive chromatin in the germ cells (Nakai et al 1991;Kubota et al 1992). In E. cirrhatus, there are also two subtypes with respect to the modal number of chromosomes in germ cells.…”

Section: Introductionmentioning

confidence: 99%

Highly repetitive DNA sequences that are restricted to the germ line in the hagfish Eptatretus cirrhatus : a mosaic of eliminated elements

1998

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The New Zealand hagfish, Eptatretus cirrhatus, is known to eliminate parts of its chromosomes during embryogenesis from presumptive somatic cells. Electrophoresis of germ line and somatic DNAs of this species, after treatment with the restriction endonucleases DraI and EcoRI, revealed three fragments of DNA that were restricted to the germ line. DNA filter hybridization experiments demonstrated that these fragments were present almost exclusively in the germ line DNA of E. cirrhatus and that they were highly and tandemly repeated. Thus, these DNA fragments appeared to be eliminated during embryogenesis. Moreover, one fragment (a DraI fragment) cross-hybridized with the germ line DNA from other species of hagfish, namely, Eptatretus okinoseanus and Paramyxine atami. Molecular cloning and sequence analysis revealed that the DraI fragment was composed mainly of closely related sequences of 85 bp in length and that this sequence was about 75% homologous to the sequence of EEEo2 (eliminated element of E. okinoseanus 2) which is a germ line-restricted and highly repetitive sequence that was isolated previously from E. okinoseanus. The other two fragments were composed of three families of closely related sequences that were 172 bp long (designated EEEc1), 61 bp long (EEEc2) and 54 bp long (EEEc3). Fluorescence in situ hybridization experiments revealed that each eliminated element was distributed on several chromosomes that are limited to germ cells. EEEo2 was dispersed on 12 C-band-positive chromosomes. EEEc1 and EEEc3 were dispersed on all C-band-positive and several C-band-negative chromosomes. By contrast, EEEc2 was located to terminal regions of several C-band-negative chromosomes. These results suggest that the eliminated chromosomes in hagfish are mosaics of highly repeated, germ line-restricted families of DNA sequences.

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“…Hemocytes are a second class of somatic cells showing B presence thus suggesting that B chromosomes in this species are not eliminated from somatic tissues as a strategy to become less harmful for the host soma but are preserving their transmission ability through the germ line (see Camacho, 2005). Examples of germ-line-restricted B chromosomes have been reported in the marsupial mammal Echymipera kalabu (Hayman et al, 1969) and the Japanese hagfi sh Eptatretus okinoseanus (Kubota et al, 1992).…”

Section: Resultsmentioning

confidence: 99%

Detection of B chromosomes in interphase hemolymph nuclei from living specimens of the grasshopper <i>Eyprepocnemis plorans</i>

Cabrero

Manrique-Poyato²,

Camacho³

2006

Cytogenet Genome Res

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The two most important evolutionary properties of B chromosomes are their transmission rate (which suggests their selfishness when significantly higher than 0.5) and their net effects on carrier fitness (usually negative for parasitic Bs). The study of transmission rate unavoidably requires the analysis of many controlled crosses in order to accurately measure population average transmission rate. Therefore, getting a marker closely associated to B presence is of crucial importance to alleviate the load of performing many useless crosses between lacking B individuals. After investigating several cytogenetic techniques on several tissues that may be sampled without drastically damaging live specimens of the grasshopper Eyprepocnemis plorans, we report here the excellent results provided by the CMA₃ fluorescence and C-banding techniques applied to hemocyte nuclei. These cells may be easily obtained from both males and females and provide information on B presence even during the interphase stage. The two cytogenetic techniques take advantage of the heterochromatic nature of the B chromosomes, so that Bs made predominantly of ribosomal DNA are revealed by CMA₃ as bright bodies in the interphase hemocytes, and Bs mostly made of satellite DNA are visualized by C-banding as intensely stained bodies in these cells.

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Germ line-restricted supernumerary (B) chromosomes in <i>Eptatretus okinoseanus</i>

Cited by 18 publications

References 8 publications

Whole chromosome elimination and chromosome terminus elimination both contribute to somatic differentiation in Taiwanese hagfish Paramyxine sheni

Whole chromosome elimination and chromosome terminus elimination both contribute to somatic differentiation in Taiwanese hagfish Paramyxine sheni

Highly repetitive DNA sequences that are restricted to the germ line in the hagfish Eptatretus cirrhatus : a mosaic of eliminated elements

Detection of B chromosomes in interphase hemolymph nuclei from living specimens of the grasshopper <i>Eyprepocnemis plorans</i>

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