Identification of homogeneously staining regions by G-banding and chromosome microdissection, and FISH marker selection using human Alu sequence primers in a scleractinian coral Coelastrea aspera Verrill, 1866 (Cnidaria)

Abstract

Karyotype analysis was performed on the scleractinian coral Coelastrea aspera Verrill, 1866, commonly found along temperate coasts in Japan (30–35°N) and in coastal waters in the Indian and Pacific oceans. G-banding of Coelastrea aspera was successfully performed, although the banding pattern was not as clear as that in mammals. The karyogram clearly revealed that this coral had a (hsr)homogeneously staining region in chromosome 11. This hsr consisted of (rRNA)ribosomal RNA related genes, which was demonstrated by (FISH)fluorescence in situ hybridization with probes generated using 28S (rDNA)ribosomal DNA primers and those generated through chromosome microdissection. In addition, we conducted (Ag-NOR)silver-stained nucleolus organizer region analysis and found Ag depositions in the interphase nuclei but not on rRNA gene loci and hsr(s) in the mitotic stage. The hsr of this coral was observed in approximately 50% of the metaphase spreads analyzed. This may explain the diversity of coral rDNA based on the molecular study of sequence analysis. Furthermore, it was discovered that human telomere and Alu repeated sequences were present in this Coelastrea aspera. Probes derived from human Alu sequences are expected to play an important role in the classification of corals. Overall, our data can be of great value in discriminating among scleractinian coral species and understanding their genetics, including chromosomal evolution.

Molecular Cytogenetic Analysis and Isolation of a 5S rRNA-Related Marker in the Scleractinian Coral <i>Platygyra contorta</i> Veron 1990 (Hexacorallia, Anthozoa, Cnidaria)

“…As a result of G-and C-banding analyses, we identified an hsr on P. contorta chromosome 12 after karyotyping. An hsr has been found previously in the corals C. aspera and E. aspera (Taguchi et al 2013(Taguchi et al , 2016. Conventional Cbanding revealed that the hsr portion of P. contorta was C-band positive (darkly stained), indicating the presence of specific proteins, such as centromere regions.…”

“…To solve the controversial taxonomic issue (Fukami et al 2004) and develop an understanding of coral genetics, we have been accumulating molecular cytogenetic data of scleractinian corals. So far, we have published three molecular cytogenetic reports using FISH on scleractinian corals, such as A. solitaryensis, E. aspera, and C. aspera (Taguchi et al 2013(Taguchi et al , 2014(Taguchi et al , 2016, which are commonly found on the western coast of Japan (Wallace 1999). The present study is our fourth report and concerns P. contorta; it is a different genus from our previous studies but is classified in the same family Merulinidae with C. aspera.…”

“…We arranged the P. contorta chromosomes in decreasing order of length using the G-and C-banding and identified chromosome 12 with an hsr. In our previous studies (Taguchi et al 2013(Taguchi et al , 2016, we revealed the presence of an hsr on chromosomes 11 and 13 through a FISH analysis of two other corals C. aspera and E. aspera, respectively, and now on chromosome 12 in P. contorta. Because the lengths of chromosomes 11, 12, and 13 were so similar, chromosome 12 may be arranged to be chromosome 11 or 13.…”

“…So far, we have reported molecular cytogenetic information on three species of stony corals, such as Acropora solitaryensis (family Acroporidae), Coleostrea aspera (family Merulinidae), and Echinophillia aspera (family Lobophylliidae). Our studies on these three species have led to several new findings, such as precise and consistent numbers of chromosomes, rRNA gene loci, and the presence of a homogenously staining region (hsr), consisting of rDNA and some coral repeated sequences shared with humans (Taguchi et al 2013(Taguchi et al , 2014(Taguchi et al , 2016.…”

Karyotypic features including organizations of the 5S, 45S rDNA loci and telomeres of Scadoxus multiflorus (Amaryllidaceae)

“…Besides these contradictory data, molecular cytogenetic approaches like (FISH)florescence in situ hybridization have not been applied in this species yet. Such methods being available since the late 1980s (Li et al 2016, Taguchi et al 2016) enable detection, characterization and localization of rDNA regions (Chirino et al 2015) and/or telomeres. The latter are known to be important to protect chromosomal ends of all eukaryotes against nucleolytic degradation, non-homologous end-joining and replication-mediated shortening.…”