Localization of 5S rDNA and 18S-5.8S-25S rDNA probes in Crinum latifolium L. genome (original) (raw)
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Genetics and Molecular Biology, 2007
The chromosomes of Crotalaria juncea, a legume of agronomic interest with a 2n = 16 karyotype composed of metacentric chromosomes, were analyzed using several cytogenetic techniques. C-banding revealed heterochromatic regions around the centromeres in all chromosomes and adjacent to the secondary constriction on the chromosome 1 short arm. Fluorescent staining with the GC-specific chromomycin A3 (CMA) highlighted these heterochromatic regions and a tiny site on the chromosome 1 long arm while the AT-specific stain 4'-6-diamidino-2-phenylindole (DAPI) induced a reversed pattern. Staining with CMA combined with AT-specific distamycin A (DA) counterstaining quenched the pericentromeric regions of all chromosomes, but enhanced fluorescence was observed at the heterochromatic regions around the secondary constriction and on the long arms of chromosomes 1 and 4. Fluorescence in situ hybridization (FISH) revealed 18S-5.8S-26S rRNA gene sites (45S rDNA) on chromosomes 1 and 4, and one 5S rDNA locus on chromosome 1. All the rDNA sites were co-located with the positive-CMA/DA bands, suggesting they were very rich in GC. Silver staining revealed signals at the main 45S rDNA locus on chromosome 1 and, in some cells, chromosome 4 was labeled. Two small nucleoli were detected in a few interphase cells, suggesting that the minor site on chromosome 4 could be active at some stages of the cell cycle.
Journal of Heredity, 2004
Fluorescence In Situ Hybridization (FISH) technique has been applied on somatic chromosomes and extended DNA fibers in the medicinally important species of Chlorophytum to elucidate physical localization and measurement of the rDNA sites using two rRNA multigene families homologous to 45S and 5S rDNA. The two species of Chlorophytum, namely C. borivillianum and C. comosum, both with 2n ¼ 28, reveal diversity for copy number and localization of rDNA sites. C. borivillianum is comprised of five 45S-rDNA sites:one each in the secondary constriction region of chromosomes 7, 8, 9; one in the subtelomeric region of the short arm of chromosome 2 and the telomeric region of the short arm of chromosome 12; and one 5S-rDNA site in the subtelomeric region of the long arm of chromosome 1. In C. comosum, there are three 45S-rDNA sites (one each in the short arm of chromosomes 12, 13, and 14) and two 5S-rDNA sites (in the secondary constriction regions of chromosomes 2 and 13). Fiber FISH analysis conducted on extended DNA fibers revealed variation in the size of continuous tandem strings for the two r-DNA families. Taking the standard value of native B DNA equivalent to 3.27 kb for 1 lm, it was estimated that the physical size of continuous DNA strings is of the order of ;90 kb, 180 kb, and 300 kb for 45S-rDNA and of the order of 60 kb, 150 kb for 5S-rDNA in C. comosum, grossly in correspondence to their respective physical sizes at metaphase. The genus Chlorophytum (family: Liliaceae) is a fairly large genus comprising over 200 species distributed in the tropical and subtropical regions of the world, mostly in Africa and Australia. Seven species commonly occurring in India exhibit tremendous morphological, chromosomal, and cytotypic diversity (
Genetic Resources and …, 2011
The genus Crotalaria is one of the largest within the family Leguminosae-Papilionoideae, with more than 600 species. However, few karyotypes have been described. In the present paper, five species belonging to the section Hedriocarpae were studied (subsection Machrostachyae), in order to better understand chromosomal evolution in Crotalaria. The results reveals that all species presented 2n = 2x = 16 with symmetrical karyotypes, and slight differences in the chromosome morphology. A secondary constriction was identified at short arm of the pair 1. The 45S rDNA was mapped in the secondary constriction and adjacent heterochromatin (NOR-heterochromatin) and a minor site was identified in C. ochroleuca. The 5S rDNA was mapped linked to 45S rDNA at chromosome 1 short arm in all species. Additional sites for 5S rDNA were identified in C. pallida, C. striata and C. mucronata. Heterochromatin blocks around the centromeres are not CMA ? neither DAPI ?. The karyotypes of the subsection Macrostachyae are characterized by an inversion at chromosome pair one in relation to previous specialized floral species analyzed. Additional sites of 45S and 5S rDNA were assumed to be a result of transposition events by different ways. The results suggest heterochromatin differentiation and the position of ribosomal genes indicates chromosomal rearrangements during evolution. Karyotype characteristics corroborate the morphological infrageneric classification.
Genetic Resources and Crop Evolution
The genus Crotalaria is one of the largest within the family Leguminosae-Papilionoideae, with more than 600 species. However, few karyotypes have been described. In the present paper, five species belonging to the section Hedriocarpae were studied (subsection Machrostachyae), in order to better understand chromosomal evolution in Crotalaria. The results reveals that all species presented 2n = 2x = 16 with symmetrical karyotypes, and slight differences in the chromosome morphology. A secondary constriction was identified at short arm of the pair 1. The 45S rDNA was mapped in the secondary constriction and adjacent heterochromatin (NOR-heterochromatin) and a minor site was identified in C. ochroleuca. The 5S rDNA was mapped linked to 45S rDNA at chromosome 1 short arm in all species. Additional sites for 5S rDNA were identified in C. pallida, C. striata and C. mucronata. Heterochromatin blocks around the centromeres are not CMA+ neither DAPI+. The karyotypes of the subsection Macrostachyae are characterized by an inversion at chromosome pair one in relation to previous specialized floral species analyzed. Additional sites of 45S and 5S rDNA were assumed to be a result of transposition events by different ways. The results suggest heterochromatin differentiation and the position of ribosomal genes indicates chromosomal rearrangements during evolution. Karyotype characteristics corroborate the morphological infrageneric classification.
Cytogenetic studies in coffee species present a lack of information caused by some cytological characteristics, such as small chromosomes, symmetric karyotypes and the remarkable genetic homogeneity presented by the genus Coffea. Cytomolecular techniques based on in situ hybridization brought up new possibilities to improve the knowledge of cytogenetic characters and cytological processes involved in speciation of taxa with these cytological features. In the present work we analyzed one cultivar (C. canephora cv. Apoatã) and two wild diploid species (C. salvatrix and C. sessiliflora) of the Coffee Germplasm Bank of IAC attempting to cytogenetic characterization. Chromosome banding with fluorochromes DAPI and CMA 3 and in situ hybridization with specific probes for rDNA sites 18S-5.8S-26S (probe pTa71) and 5S (probe pScT7) were carried out. For C. salvatrix and C. sessiliflora the CMA 3 positive bands agreed with the in situ hybridized rDNA sites in number, size and position. The little variation in number and length of the rDNA sites between species of coffee is discussed.
Molecular and Cytogenetic Analysis of rDNA Evolution in Crepis Sensu Lato
International Journal of Molecular Sciences, 2022
Although Crepis was the first model plant group in which chromosomal changes were considered to play an important role in speciation, their chromosome structure and evolution have been barely investigated using molecular cytogenetic methods. The aim of the study was to provide a better understanding of the patterns and directions of Crepis chromosome evolution, using comparative analyses of rDNA loci number and localisation. The chromosome base number and chromosomal organisation of 5S and 35S rDNA loci were analysed in the phylogenetic background for 39 species of Crepis, which represent the evolutionary lineages of Crepis sensu stricto and Lagoseris, including Lapsana communis. The phylogenetic relationships among all the species were inferred from nrITS and newly obtained 5S rDNA NTS sequences. Despite high variations in rDNA loci chromosomal organisation, most species had a chromosome with both rDNA loci within the same (usually short) chromosomal arm. The comparative analyses r...
Ribosomal DNA localization on Lathyrus species chromosomes by FISH
2020
Background Fluorescence In Situ Hybridization (FISH) played an essential role to locate the ribosomal RNA genes on the chromosomes that offered a new tool to study the chromosome structure and evolution in plant. The 45S and 5S rRNA genes are independent and localized at one or more loci per the chromosome complement, their positions along chromosomes offer useful markers for chromosome discriminations. In the current study FISH has been performed to locate 45S and 5S rRNA genes on the chromosomes of nine Lathyrus species belong to five different sections, all have chromosome number 2n=14, Lathyrus gorgoni Parl, Lathyrus hirsutus L., Lathyrus amphicarpos L., Lathyrus odoratus L., Lathyrus sphaericus Retz, Lathyrus incospicuus L, Lathyrus paranensis Burkart, Lathyrus nissolia L., and Lathyrus articulates L. Results The revealed loci of 45S and 5S rDNA by FISH on metaphase chromosomes of the examined species were as follow: all of the studied species have one 45S rDNA locus and one 5S...
Molecular and cytogenetic characterization of Crassostrea angulata chromosomes
Aquaculture, 2005
We have conducted a molecular cytogenetic study of Crassostrea angulata, by treating its mitotic chromosomes with Cbanding, fluorochrome and oligopeptide staining, restriction enzyme banding and fluorescent in situ hybridization, using three repetitive or multicopy DNAs (the GATA sequence, the TTAGGG telomeric repeat and the 5S rDNA). Results on C-banding indicate the presence of heterochromatin in several chromosomes occupying telomeric positions. The staining with DAPI, DA/ DAPI and AMD/DAPI allow concluding that large regions rich in AT in the chromosomes of C. angulata do not exist. Restriction banding has shown few restriction sites for AluI (AGTC site) and a relative abundance of G-C in terminal and interstitial chromosome regions, inferred by the digestion with HaeIII (GGCC site) and BamHI (GGATCC site). In situ hybridization with GATA indicated that these repeated sequences are widely dispersed in the genome of this species, whereas hybridization with the telomeric repeat revealed small bright hybridization signals, uniform in size and intensity, on each telomere of all chromosomes but not in interstitial positions. Location of 5S rDNA displayed the presence of two 5S-bearing chromosome pairs, of large size, on the subterminal position of the karyotype of C. angulata, this location being different from the ones encoding the major ribosomal genes in chromosome pair 10 (described in a previous paper).
CYTOLOGIA, 2005
Detailed karyotypes of diploid Aster ageratoides var. ageratoides (2nϭ18), diploid A. iinumae (ϭKalimeris pinnatifida) (2nϭ18) and tetraploid A. microcephalus var. ovatus (2nϭ36) were constructed on the basis of chromosome lengths, arm ratios and multi color fluorescence in situ hybridization (McFISH) with 5S and 18S ribosomal RNA gene sequences as probes. The karyotype of A. iinumae was morphologically similar to those of A. ageratoides var. ageratoides, however, the size of the chromosomes of A. iinumae was apparently smaller (S-type chromosomes) compared to those of A. ageratoides (L-type chromosomes). The chromosomes of A. microcephalus var. ovatus, a putative amphidiploid between them consisted of the 18 large chromosomes (L-type chromosomes) and the 18 smaller chromosomes (S-type chromosomes). The McFISH with 5S rDNA and 18S rDNA of each A. ageratoides and A. iinumae chromosomes tagged 4 out of 18 chromosomes. Whereas A. microcephalus var. ovatus have 5S rDNA and 18S rDNA sites equal to the sum of the numbers in the two diploids (A. ageratoides and A. iinumae), 4 on the L-type chromosomes and 4 on the S-type chromosomes. The locations of the rDNA sites in A. microcephslus var. ovatus are corresponding to those of A. ageratoides and A. iinumae.