Constitutive heterochromatin DNA polymorphisms in diploid Medicago sativa ssp. falcata

Genome ◽  
1999 ◽  
Vol 42 (5) ◽  
pp. 930-935 ◽  
Author(s):  
G R Bauchan ◽  
M A Hossain
Keyword(s):  
Medicago Sativa ◽  
Banding Pattern ◽  
Constitutive Heterochromatin ◽  
Nucleolar Organizer ◽  
Dna Polymorphisms ◽  
Banding Technique ◽  
Chromosome 3 ◽  
Nucleolar Organizer Regions ◽  
First Report ◽  
C Banding

A Giemsa C-banding technique was used to study the amount and location of constitutive heterochromatin in diploid (2n = 2x = 16) Medicago sativa ssp. falcata (L.) Arcangeli. Most accessions had the standard C-banding pattern with centromeric bands on all the chromosomes and a prominent heterochromatic band at the nucleolar organizer regions (NOR) of the satellited (SAT) chromosomes. However, we observed in various accessions that constitutive heterochromatic C-bands can exist at the telomeric ends of all the chromosomes. Interstitial bands occurred on the short arms of all chromosomes except for chromosome 3 and on the long arms of chromosomes 1, 2, 3, and 6, only. Rearranged chromosomes such as isochromosomes have been observed for the short arms of chromosomes 2 and 6. This is the first report on the existence of C-banding polymorphisms and the detection of putative isochromsomes in the chromosomes of diploid ssp. falcata which could have contributed to the variation observed in cultivated alfalfa.Key words: alfalfa, C-bands, chromosome, isochromosome.

scholarly journals Cytogenetic analysis of the neotropical spider Nephilengys cruentata (Araneomorphae, tetragnathidae): standard staining, NORs, C-bands and base-specific fluorochromes

2005 ◽  
Vol 65 (2) ◽  
pp. 193-202 ◽  
Author(s):  
D. Araújo ◽  
D. M. Cella ◽  
A. D. Brescovit
Keyword(s):  
Sex Determination ◽  
Banding Pattern ◽  
Constitutive Heterochromatin ◽  
Repetitive Sequences ◽  
Nucleolar Organizer ◽  
Pericentromeric Region ◽  
Banding Technique ◽  
Nucleolar Organizer Regions ◽  
Fluorochrome Staining ◽  
C Banding

The aim of this work is to characterize Nephilengys cruentata in relation to the diploid number, chromosome morphology, type of sex determination chromosome system, chromosomes bearing the Nucleolar Organizer Regions (NORs), C-banding pattern, and AT or GC repetitive sequences. The chromosome preparations were submitted to standard staining (Giemsa), NOR silver impregnation, C-banding technique, and base-specific fluorochrome staining. The analysis of the cells showed 2n = 24 and 2n = 26 chromosomes in the embryos, and 2n = 26 in the ovarian cells, being all the chromosomes acrocentric. The long arm of the pairs 1, 2 and 3 showed an extensive negative heteropycnotic area when the mitotic metaphases were stained with Giemsa. The sexual chromosomes did not show differential characteristics that allowed to distinguish them from the other chromosomes of the complement. Considering the diploid numbers found in N. cruentata and the prevalence of X1X2 sex determination chromosome system in Tetragnathidae, N. cruentata seems to possess 2n = 24 = 22 + X1X2 in the males, and 2n = 26 = 22 + X1X1X2X2 in the females. The pairs 1, 2 and 3 showed NORs which are coincident with the negative heteropycnotic patterns. Using the C-banding technique, the pericentromeric region of the chromosomes revealed small quantity or even absence of constitutive heterochromatin, differing of the C-banding pattern described in other species of spiders. In N. cruentata the fluorochromes DAPI/DA, DAPI/MM and CMA3/DA revealed that the constitutive heterochromatin is rich in AT bases and the NORs possess repetitive sequences of GC bases.

C-banding pattern and nucleolar organizer regions of Cynoglossus semilaevis Gunther, 1873*

2006 ◽  
Vol 16 (7) ◽  
pp. 769-772
Author(s):  
Wu Di ◽  
Zhang Shicui ◽  
ZHUANG Zhimeng ◽  
Pang Qiuxiang ◽  
Wang Changliu ◽  
...  
Keyword(s):  
Banding Pattern ◽  
Nucleolar Organizer ◽  
Cynoglossus Semilaevis ◽  
Nucleolar Organizer Regions ◽  
C Banding

scholarly journals Karyotype, constitutive heterochromatin and nucleolar organizer regions (NORs) in Belosacris coccineipes (Acrididae-Leptysminae)

2000 ◽  
Vol 23 (3) ◽  
pp. 575-579 ◽  
Author(s):  
Vilma Loreto ◽  
Maria José de Souza
Keyword(s):  
Sex Determination ◽  
Silver Nitrate ◽  
X Chromosome ◽  
Silver Staining ◽  
Constitutive Heterochromatin ◽  
Nucleolar Organizer ◽  
Nucleolar Organizer Regions ◽  
C Banding ◽  
Nucleolar Organizers ◽  
Silver Nitrate Staining

Several techniques including C-banding, fluorochromes and silver staining were used to obtain information about heterochromatin patterns in the grasshopper B. coccineipes. Conventional staining showed a karyotype with 2n = 23 chromosomes in males and 2n = 24 in females, as well as XO:XX sex determination and acrotelocentric chromosomes. The medium-sized X chromosome was heteropycnotic positive at the beginning of prophase I and negative in metaphase I. C-banding revealed heterochromatic blocks in the pericentromeric regions of all chromosomes. Silver nitrate staining in this species showed three small bivalents (S9-S11) as nucleolar organizers with NORs located in the pericentromeric regions. CMA3-positive blocks were seen in pericentromeric regions of pairs M6, S9, S10 and S11. Sequential staining with CMA3/AgNO3 revealed homology between the CMA3-positive bands and NORs of the bivalents S9, S10 and S11. The CMA3-positive block of the bivalent M6 could represent a latent secondary NOR. The results obtained permit us to distinguish two categories of the constitutive heterochromatin in B. coccineipes.

scholarly journals First Report on Nucleolar Organizer Regions (NORs) Polymorphism and Constitutive Heterochromatin of Moonlight Gourami, Trichopodus microlepis (Perciformes, Osphronemidae)

Caryologia ◽  
2021 ◽  
Author(s):  
Weerayuth Supiwong
Keyword(s):  
Chromosome Pair ◽  
Constitutive Heterochromatin ◽  
Sex Chromosome ◽  
Nucleolar Organizer ◽  
Nucleolar Organizer Regions ◽  
Mitotic Chromosomes ◽  
First Report ◽  
Telocentric Chromosomes ◽  
Karyotype Formula ◽  
Males And Females

Nucleolar organizer regions (NORs) polymorphism, constitutive heterochromatin and chromosomal analysis of Moonlight gourami, Trichopodus microlepis in Thailand were firstly reported. Specimens were collected from the Chao Phraya and Mekong Basins, Thailand. The mitotic chromosomes were directly prepared from kidney tissues of ten males and ten females. Conventional staining, Ag-NOR banding and C- banding techniques were applied to stain the chromosomes. The results shown that the diploid chromosome number of T. microlepis was 2n=46 and the fundamental number (NF) was 46 in both males and females. The karyotype consisted of 46 telocentric chromosomes classifying as 14 large and 32 medium. No heteromorphic sex chromosome was observed in T. microlepis. The results also exhibited that the interstitial nucleolar organizer regions (NORs) were clearly observed at the long arm of the chromosome pair 7. This is the first report on NORs polymorphism in T. microlepis that a heteromorphic NOR type in one female had a single NOR-bearing chromosome of the chromosome pair 7, whereas 10 males and nine females had two NOR-bearing chromosomes of the chromosome pair 7 with a homomorphic NOR type. Constitutive heterochromatins located at all centromeres of all chromosome pairs. The karyotype formula of T. microlepis is 2n (46) = Lt14 + Mt32.

Structure and variability of nucleolar organizer regions in Parodontidae fish

1984 ◽  
Vol 26 (5) ◽  
pp. 564-568 ◽  
Author(s):  
Orlando Moreira-Filho ◽  
Luiz Antonio Carlos Bertollo ◽  
Pedro Manoel Galetti Jr.
Keyword(s):  
Chromosome Pair ◽  
Constitutive Heterochromatin ◽  
Nucleolar Organizer ◽  
Nucleolar Organizer Regions ◽  
Mitotic Chromosomes ◽  
Homozygous Condition ◽  
Nucleolar Organizing Regions ◽  
Nucleolar Chromosome

Nucleolar organizer regions (NORs) were studied in mitotic chromosomes of four species of fish of family Parodontidae: Parodon tortuosus, Apareiodon affinis, Apareiodon ibitiensis, and Apareiodon piracicabae. All four species exhibited only a single nucleolar chromosome pair in their karyotypes. Intraspecific differences were observed in the size of these chromosomes; however, these were not very clear for A. affinis and A. piracicabae, Apareiodon piracicabae exhibited two clearly visible NORs in each of the nucleolar chromosomes, which was the only configuration practically found in this species. This trait therefore predominates in a homozygous condition in the population investigated. Regions of constitutive heterochromatin adjacent to the two NORs were detected. Possible mechanisms that may have originated the two NORs are discussed.Key words: nucleolar organizing regions, fish.

scholarly journals Cytogenetical analyses in three fish species of the genus Pimelodus(Siluriformes: Pimelodidae) from rio São Francisco: considerations about the karyotypical evolution in the genus

2005 ◽  
Vol 3 (2) ◽  
pp. 285-290 ◽  
Author(s):  
Caroline Garcia ◽  
Orlando Moreira Filho
Keyword(s):  
Chromosome Pair ◽  
Chromosomal Rearrangements ◽  
Nucleolar Organizer ◽  
Differential Staining ◽  
Nucleolar Organizer Regions ◽  
C Banding ◽  
Heteromorphic Sex Chromosomes ◽  
Chromosomal Markers ◽  
Staining Techniques ◽  
Species Specific

Karyotypes and other chromosomal markers were investigated in three species of the catfish genus Pimelodus, namely P. fur, P. maculatus and Pimelodus sp., from municipality of Três Marias, Minas Gerais, Brazil, using differential staining techniques (C-banding, Silver nitrate and CMA3 staining). The diploid chromosome number was 2n = 56 in P. maculatus and Pimelodus sp., while in P. fur 2n = 54. The karyotype of P. fur consisted in 32M + 8SM + 6ST + 8A with fundamental number (NF) of 100, that of P. maculatus 32M + 12SM + 12A with NF = 112, and that of Pimelodus sp. had 32M + 12Sm + 6ST + 6A with NF = 106.The nucleolar organizer regions (NORs) in all three species were invariably detected in telomeres of longer arm of the 20th chromosome pair. These sites were also positive after CMA3 and C-banding. No heteromorphic sex chromosomes were detected and C-banding pattern was species specific. Inferences about the karyotype differentiation in Pimelodus and putative chromosomal rearrangements are hypohesized.

C-Banding and Nucleolar Organizer Regions of Sphoeroides greeleyi (Tetraodontidae, Tetraodontiformes)

Caryologia ◽  
2002 ◽  
Vol 55 (2) ◽  
pp. 171-174 ◽  
Author(s):  
Mario Jorge Ignacio Brum ◽  
Liliane Cristine Gomes Mota
Keyword(s):  
Nucleolar Organizer ◽  
Nucleolar Organizer Regions ◽  
C Banding
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