Incipient sex chromosome differentiation in an isopod crustacean species, Asellus aquaticus

Rocchi, A.; Prantera, Giorgio; Lanza, Valentina; Castro, M. Di

doi:10.1007/bf00294998

Cited by 19 publications

(10 citation statements)

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“…The same staining properties are also shown by two interstitial heterochromatic regions located on a probable Y chromosome undergoing morphological differentiation, which is present in part of the males of a natural population (Rocchi et al 1980(Rocchi et al , 1984.…”

Section: Discussionsupporting

confidence: 51%

“…These areas display a high degree of polymorphism, involving not only their number but also their size (Rocchi et al 1980). Rocchi et al (1980Rocchi et al ( , 1984 found that some males of a Sarno River population had two interstitial heterochromatic areas on one of the chromosomes of a pair that possessed the same staining properties as telomeric heterochromatin. This chromosome is inherited through the male line as a normal Y chromosome and probably represents an early stage of morphological differentiation of a sex chromosome.…”

Section: Introductionmentioning

confidence: 98%

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Heterochromatin and ribosomal genes inAsellus aquaticus (Crust. Isop.)

1996

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In the present investigation chromosomal preparations of Asellus aquaticus were sequentially stained with chromomycin A3 to reveal the heterochromatic areas, hybridized in situ with rDNA probes in order to map the ribosomal genes and finally silver stained to check the transcriptional activity of these genes. The results indicate the existence of a substantial correspondence of location and size among the heterochromatic regions and the regions over which the in situ hybridization signals spread. The ribosomal genes, quite independently of their location in the secondary constriction, can be silver stained and thus appear to be transcriptionally active. The ribosomal sequences also hybridize to the entire heterochromatic areas observed on the probable Y chromosome identified in some males of a natural population. These rRNA genes are only rarely transcriptionally active.

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Section: Discussionsupporting

confidence: 51%

Section: Introductionmentioning

confidence: 98%

Heterochromatin and ribosomal genes inAsellus aquaticus (Crust. Isop.)

1996

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“…Crossing-over seldom takes place in the region between the two heterochromatic areas. These exchanges obviously give rise to heterochromosomes with a single heterochromatic region which are in fact found in a small percentage of both male and female individuals (Rocchi et a!., 1984). All this suggests that the heteromorphic pair has retained a high degree of genetic homology and Several different hypotheses have been advanced to account for the appearance of heterochromatic areas in different organisms.…”

Section: Discussionmentioning

confidence: 99%

Morphological differentiation of a sex chromosome and ribosomal genes in Asellus aquaticus (Crust. Isop.)

et al. 1992

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The karyotype of the isopod crustacean Asellus aquaticus does not normally display any\ud heteromorphic sex chromosome pair. Some of the males in a wild population of A. aquaticus\ud collected in the Sarno river near Naples do display a heteromorphic chromosome pair. The heteromorphism\ud is due to the presence of two intercalary heterochromatic areas on one chromosome.\ud This chromosome is inherited through the male line as a normal Y chromosome. The heteromorphic\ud pair has retained the capacity to recombine during meiosis. In-situ hybridization of ribosomal\ud probes, labelled with digoxigenin—dUTP, reveals that ribosomal sequences are associated\ud with both intercalary heterochromatic areas of the heterochromosome. The ribosomal genes are\ud normally telomeric and associated with heterochromatin. After digestion of genomic DNA with\ud BamHI, EcoRl and HindIII restriction endonucleases and hybridization with ribosomal probes, the\ud hybridization patterns of the males with the heterochromosome differ from those of the males without\ud the heterochromosome, as well as from those of the females, which are identical. The possible\ud origin of the morphological differentiation of the heterochromosome, and the causes of the differences\ud in the ribosomal DNA restriction patterns linked to the presence of this chromosome, are discussed

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“…The Y chromosome has two intercalary areas that harbour ribosomal variant sequences (Rocchi et a!., 1984;Volpi et al, 1992). Meiotic recombination within the heteromorphic pair often occurs in the subterminal regions distal to the heterochromatic bands, but is very rarely observed in the region situated between them.…”

Section: Sex Chromosome Differentiation In a Crustacean 271mentioning

confidence: 99%

Simple DNA repeats and sex chromosome differentiation in Asellus aquaticus (Crustacea, Isopoda)

et al. 1995

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The crustacean isopod species Asellus aquaticus does not usually have recognizable sex chromosomes. We previously identified a Y chromosome marked by two heterochromatic bands in some males of a population from the Sarno river near Naples. In this work we used oligonucleotide probes to test the presence and possible sex-specific distribution of five simple repeat motifs in the genome of male and female individuals from the Sarno population. The five oligonucleotide probes were hybridized to enzyme-restricted genomic DNAs and the chromosome location of two probes was tested using fluorescence in situ hybridization. Our results show that only the (TCC) repetitive simple sequence has a sex-specific hybridization pattern and presents a significant accumulation on the Y chromosome in the region included between the two heterochromatic areas. Moreover the GGAAT sequence is not present in the genome of A. aquaticus in any detectable quantity.

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Incipient sex chromosome differentiation in an isopod crustacean species, Asellus aquaticus

Cited by 19 publications

References 10 publications

Heterochromatin and ribosomal genes inAsellus aquaticus (Crust. Isop.)

Heterochromatin and ribosomal genes inAsellus aquaticus (Crust. Isop.)

Morphological differentiation of a sex chromosome and ribosomal genes in Asellus aquaticus (Crust. Isop.)

Simple DNA repeats and sex chromosome differentiation in Asellus aquaticus (Crustacea, Isopoda)

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