Cytotaxonomic studies of Encarsia Förster (Hymenoptera: Aphelinidae)

1999 ◽  
Vol 89 (3) ◽  
pp. 209-215 ◽  
Author(s):  
F. Baldanza ◽  
L. Gaudio ◽  
G. Viggiani
Keyword(s):  
Chromosome Number ◽  
Cryptic Species ◽  
Silver Staining ◽  
Nucleolar Organizer ◽  
Nucleolar Organizer Regions ◽  
Economic Interest ◽  
C Banding ◽  
Cytogenetic Studies ◽  
Karyological Data ◽  
Karyotype Differentiation

AbstractA cytotaxonomic study was carried out on 13 species of Encarsia Förster, known to parasitize aleyrodids and diaspidids. The chromosomes varied greatly both in number and morphology, with E. protransvena Viggiani having the lowest chromosome number (2n = 6) and E. asterobemisiae Viggiani & Mazzone the highest (2n = 20). The most common chromosome number was 2n = 10. C-banding, G-banding and silver staining for nucleolar organizer regions (NOR) provided the possibility of distinguishing between karyotypes with the same chromosome number and morphology and to identify all the pairs of homologues in a diploid set for advanced cytogenetic studies. The karyotype of Coccophagus lycimnia (Walker) was also examined. The chromosome data suggested that in Encarsia, karyotype differentiation has mainly occurred through a series of centric fusions, although other rearrangements may also have been significant. The importance of karyological data in systematic studies and in the identification of biotypes and cryptic species of economic interest is outlined.

Extensive multivalent pairing occurs in male lake trout meiosis

Genome ◽  
1990 ◽  
Vol 33 (2) ◽  
pp. 219-224 ◽  
Author(s):  
Jane E. Disney ◽  
James E. Wright Jr.
Keyword(s):  
Silver Staining ◽  
Lake Trout ◽  
Nucleolar Organizer ◽  
Salvelinus Namaycush ◽  
Nucleolar Organizer Regions ◽  
Robertsonian Fusion ◽  
C Banding

Extensive multivalent pairing was observed in the tetraploid derivative lake trout (Salvelinus namaycush). In conjunction with previously reported hybrid splake (brook × lake) trout data, this result supports a meiotic model to explain the phenomenon of pseudolinkage. In addition, C-banding of mitotic and meiotic lake trout chromosomes revealed an intraindividual polymorphism for a Robertsonian fusion. Silver staining of lake trout chromosomes showed that the chromosomes with active nucleolar organizer regions located proximal to a centromere were not involved in the fusion event.Key words: lake trout, mitosis, C-banding, nucleolar organizer regions, intraindividual Robertsonian polymorphism, meiosis.

Note on the karyotype and NOR phenotype of leuciscine fish Acanthobrama marmid (Osteichthyes, Cyprinidae)

Biologia ◽  
2006 ◽  
Vol 61 (2) ◽  
Author(s):  
Muhammet Gaffaroglu ◽  
Esref Yuksel ◽  
Petr Ráb
Keyword(s):  
Chromosome Number ◽  
Sex Chromosomes ◽  
Silver Staining ◽  
Chromosome Pair ◽  
Nucleolar Organizer ◽  
Cyprinid Fish ◽  
Nucleolar Organizer Regions ◽  
Heteromorphic Sex Chromosomes ◽  
Nor Phenotype ◽  
Acrocentric Chromosomes

AbstractThe karyotype and major ribosomal sites as revealed using silver staining of Anatolian leuciscine cyprinid fish Acanthobrama marmid were studied. The diploid chromosome number was invariably 2n = 50. Karyotype consisted of eight pairs of metacentric, 13 pairs of submetacentric and four pairs of subtelocentric to acrocentric chromosomes. The largest chromosome pair of the complement was subtelo-to acrocentric characteristically, which is a characteristic cytotaxonomic marker for representatives of the cyprinid lineage Leuciscinae. The nucleolar organizer regions (NORs) were detected in the telomeres of two pairs of medium sized submeta-to subtelocentric chromosomes. No heteromorphic sex chromosomes were found. The karyotype pattern of A. marmid is nearly identical to that found in most other representatives of the Eurasian leuciscine cyprinids, while the multiple NOR phenotype appears to be more derived as opposed to a uniform one, ubiquitous in this group.

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.

Sequential silver staining and in situ hybridization reveal a direct association between rDNA levels and the expression of homologous nucleolar organizing regions: a hypothesis for NOR structure and function

1998 ◽  
Vol 111 (10) ◽  
pp. 1433-1439
Author(s):  
F. Zurita ◽  
R. Jimenez ◽  
M. Burgos ◽  
R.D. de la Guardia
Keyword(s):  
Transcription Factors ◽  
In Situ Hybridization ◽  
Silver Staining ◽  
Organizer Region ◽  
Nucleolar Organizer ◽  
Interindividual Variation ◽  
Nucleolar Organizer Regions ◽  
Single Pair ◽  
Ribosomal Cistrons

We have developed a procedure for sequential silver staining and in situ hybridization to analyze the relationship between the amount of rDNA present in nucleolar organizer regions, as estimated by in situ hybridization, and their level of expression, as estimated by the silver signal. For simplicity we used cells from the insectivorous mole Talpa occidentalis, which have a single pair of nucleolar organizer regions in chromosome pair 3. The relative content of ribosomal cistrons was also related to the hierarchy of activation of the nucleolar organizer regions present in this chromosomal pair. Statistical analyses demonstrated that both the relative level of expression and the activation hierarchy depended mainly on the number of ribosomal cistrons in nucleolar organizer regions. We propose a functional two-step hypothesis, which is consistent with most known data concerning interchromosomal, intercellular and interindividual variation in a number of plant and animal species, including Talpa occidentalis. In step one, the first available transcription factors bind randomly to the ribosomal promoters, such that larger nucleolar organizer regions are more likely to recruit them. In the second step the remaining transcription factors are recruited in a cooperative way, thus completing activation of one nucleolar organizer region, before the next one becomes active.

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

Chromosomal analysis of the leptodactylids Pleurodema diplolistris and Physalaemus nattereri (Amphibia, Anura)

2006 ◽  
Vol 27 (4) ◽  
pp. 481-489 ◽  
Author(s):  
Luciana B. Lourenço ◽  
Josiane A.A. Nascimento ◽  
Gilda V. Andrade ◽  
Denise C. Rossa-Feres ◽  
Shirlei M. Recco-Pimentel
Keyword(s):  
Nucleolar Organizer ◽  
The Other ◽  
Chromosomal Analysis ◽  
Nucleolar Organizer Regions ◽  
Chromosome 11 ◽  
Similar Morphology ◽  
C Banding ◽  
Heterochromatic Block

Abstract Detailed characterizations of the karyotypes of the Brazilian leptodactylid frogs Pleurodema diplolistris, the only species of Pleurodema not studied cytogenetically so far, and Physalaemus nattereri, a species in the Ph. biligonigerus group, are presented. Both karyotypes had 2n = 22 and their chromosomes had a very similar morphology, except for pair 11, which was metacentric in Pl. diplolistris and telocentric in Ph. nattereri. The localization of nucleolar organizer regions (NORs) and heterochromatic bands allowed the differentiation of chromosomes that were morphologically indistinguishable between these species, such as pairs 1, 3 and 10, which showed interstitial C-bands in Ph. nattereri, and pair 8, that had an NOR and an adjacent C-band in Pl. diplolistris. Pair 8 also has NOR-bearing chromosomes in many other Pleurodema species. However, in these species, the NOR is located proximal to the centromere on the short arm, while in Pl. diplolistris it occurred distally on the long arm, a condition that may be considered a derived state. In Ph. nattereri, the NOR occurred on chromosome 11 and differed from the other species of the Ph. biligonigerus group. In contrast, C-banding revealed a heterochromatic block near the centromere on the short arm of pair 3, a characteristic common to all members of this group of Physalaemus.

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