Chromosome Science
Online ISSN : 2185-0852
Print ISSN : 1344-1051
ISSN-L : 1344-1051
Volume 13, Issue 1+2
Displaying 1-5 of 5 articles from this issue
Regular Article
  • Dibyendu Talukdar
    2011 Volume 13 Issue 1+2 Pages 3-10
    Published: 2011
    Released on J-STAGE: June 03, 2011
    JOURNAL FREE ACCESS
    Karyotype analysis of three improved grass pea (Lathyrus sativus L.) varieties, namely Nirmal, BioL-203 and BioR-231 was carried out using root tip metaphase cells after staining with orcein and with two DNA base specific fluorochromes, Chromomycin A3 (CMA) and 4-6'diamidino 2-phenyle indole (DAPI). It was revealed that the three varieties were diploids showing 2n=14 with metacentric and submetacentric chromosomes. The three varieties showed minor variations in conventional orcein staining, but were distinctly different from each other in GC-specific CMA and AT-specific DAPI-banding patterns. CMA-stained regions fluoresced as bright bands mainly in terminal secondary constriction and peri-centromeric regions, while DAPI-stained parts were highlighted both as bands and pairs of dots in terminal regions of different pairs. The study revealed conspicuous differences among seven pairs of chromosomes and presence of one pair of chromosomes with secondary constriction, pair 1 in BioR-231 and pair 2 in both BioL-203 and Nirmal, containing GC-rich repeats. Among the varieties, Nirmal contained the highest percentage of GC-rich sequences exhibiting 12 CMA-positive bands, and it was followed by BioL-203 (10 bands) and BioR-231(eight bands). In DAPI-banding, the highest number of bands (12) was scored in BioL-203, followed by BioR-231 (10) and Nirmal (eight). The variation in banding patterns suggests the presence of karyomorphological polymorphism in the present materials.
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  • Shinji Kikuchi, Hisashi Tsujimoto, Hidenori Sassa, Takato Koba
    2011 Volume 13 Issue 1+2 Pages 11-16
    Published: 2011
    Released on J-STAGE: June 03, 2011
    JOURNAL FREE ACCESS
    Jatropha is considered a promising crop for the production of biodiesel; however, a standard karyotype based on fluorescent in situ hybridization (FISH) analysis has not yet been constructed. In this paper, we describe the isolation of a tandem repeat sequence, JcSat1 (Jatropha curcas satellite 1). The sequence consists of a repeat unit of 358-360 bp including a telomere repeat sequence and is located in the subtelomeric heterochromatin. The intensity of JcSat1 signal varied between loci, allowing the identification of six out of eleven pairs of Jatropha chromosomes. FISH analysis of the nuclei of meiotic cells revealed the non-Rabl distribution of JcSat1 and the telomere bouquet structure. Our results suggest that JcSat1 together with other chromosome markers, such as ribosomal DNAs, will help in the identification of each Jatropha chromosome and analysis of the chromosome dynamics during mitosis and meiosis.
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  • Rama Srinivas Talluri
    2011 Volume 13 Issue 1+2 Pages 17-20
    Published: 2011
    Released on J-STAGE: June 03, 2011
    JOURNAL FREE ACCESS
    The occurrence of nucleolar dominance has been recorded in many interspecific hybrids where in the rRNA genes inherited from one of the parents are transcribed and those derived from the other parent are silent. In a total of 125 cross combinations attempted by interspecific hybridization in Fuchsia, this phenomenon was observed in the interspecific hybrid (2n=22) between F. triphylla and F. arborescens during the cytogenetic studies carried out using root tip squash technique, air dried chromosome spreads, and silver staining of Nucleolar Organizer Regions (NORs). In this interspecific hybrid, only one chromosome expressed the secondary constriction derived from one of its parental species at mitotic metaphase. It is presumed that NOR of F. triphylla with the genome size of 1643 Mbp might have failed to display its secondary constriction and was suppressed by F. arborescens with genome size of 1594 Mbp as underdominant rRNA genes in the plant hybrids present from the larger genome of the parental species, rich in repetitive DNA in heterochromatin.
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  • Rama Srinivas Talluri
    2011 Volume 13 Issue 1+2 Pages 21-26
    Published: 2011
    Released on J-STAGE: June 03, 2011
    JOURNAL FREE ACCESS
    The meiotic analysis of Fuchsia species revealed the incidence of a low frequency of univalents in diploids with less than 100% of pollen viability. Bivalent formation in the polyploid species such as F. hatschbachii, F. glazioviana, and F. boliviana with occasional univalents in F. magellanica suggests that these species are allotetraploids. In the hybrids, the extent of chromosome pairing at metaphase I was varied. The regular bivalent pairing observed in the interspecific hybrids of the diploid species suggests that F. fulgens, F. splendens, and F. triphylla all have homologous genomes with no structural heterozygosity differentiating them. The fertility in many hybrids is less than that of their parents which has been related to both chromosomal and genic sterility, a reflection of the meiotic irregularities. Reciprocal interchromosomal translocations that differentiate the parental chromosomes resulted in the formation of quadrivalents in some of the hybrids and these translocation heterozygotes showed reduced fertility (<50%).
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Short communication
  • Go Suzuki, Maho Shiomi, Sayuri Morihana, Yasuhiko Mukai
    2011 Volume 13 Issue 1+2 Pages 27-29
    Published: 2011
    Released on J-STAGE: June 03, 2011
    JOURNAL FREE ACCESS
    Onion, Allium cepa, is a model plant for experimental observation of mitotic cell division in practice of fundamental biology, because its chromosome is big and easy to observe. In order to develop new academic tools for visualization of plant cytokinesis, molecular cloning of onion mitotic genes, which are related to cell division, cell cycle, and chromosome segregation, is indispensable. Here we isolated CDC48 cDNA (AcCDC48) from onion seedlings, which encodes an AAA-ATPase chaperone and is known to play a role in cell division in broad species of organism. To characterize AcCDC48, we performed phylogenetic and DNA gel blot analyses, and discussed about the possible application of mammalian antibodies to detect it. The full-length onion CDC48 sequence provides useful information for future development of molecular markers to visualize cell division by using antibodies or GFP-fusion proteins.
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