Morphology of the axial structures in the neo-XY sex bivalent of Pycnogaster cucullata (Orthoptera) by silver impregnation

Sentís, C.; Rodríguez-Campos, Antonio; Stockert, Juan C.; Fernández‐Piqueras, José

doi:10.1007/bf00287041

Cited by 19 publications

(16 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…id). This fact could indicate the existence of a new "latent NOR" at this position where two silver spots can be seen throughout meiosis in most of the individuals analysed so far (SentIs et a!., 1984 to a postmeiotical reactivation of NORs already described in other species (Hofgärtner et a!., 1979;Schmid eta!., 1982). Nucleolar precipitates and/or Ag NORs throughout male meiosis have also been described in other species (Di Castro et a!., 1983;Loidi and Greilhuber, 1983;Cuñado et a!., 1986) including orthopteroid insects (Satya-Prakash and Pathak, 1984;Santos eta!., 1987).Thevisualisation of nucleolus-like structures during interkinesis-LI and prophase-Il does not necessarily imply transcriptional activity of rDNA at these stages.…”

Section: Number and Location Of Active Norsmentioning

confidence: 53%

“…Some slides were pretreated with 2 x SSC (0.15 M NaCl+0015 M sodium citrate) at 60°C for 15 minutes to achieve a clear differentiation of the axial structures in the metaphase-I bivalents at previously described (SentIs et a!., 1984 Table I Distribution of active sNORs in the sampled populations of the genus Pycnogaster…”

Section: Methodsmentioning

confidence: 99%

“…The neo XY race had arisen by a centric fusion between a member of the M2 pair and the X chromosome at the XO state, becoming the unfused M2 in the neo Y chromosome. Nevertheless, secondary modifications during the establishment of the neo XY race involved the loss of the nucleolar region at the proximal region of the neo Y (Fernández- Piqueras et a!., 1982bPiqueras et a!., , 1983aSentIs et al, 1984).…”

Section: The Chromosome Complementmentioning

confidence: 99%

See 2 more Smart Citations

Primary and secondary nucleolar organiser regions during spermatogenesis in the genus Pycnogaster

1988

View full text Add to dashboard Cite

Two different types of Nucleolar Organiser Regions (NORs) and associated nucleoli, which differ in morphology and the meiotic behaviour of their silver precipitates, have been found in all species of the genus Pycnogaster. The so-called primary nucleoli are present in all cells from each analysed individual, while secondary nucleoli are only present in some individuals and, within these, are not found in all the analysed cells. The chromosomal location of both types of NORs is highly conserved in this genus although the most frequently active secondary NOR is not necessarily the same in all the analysed populations or species. Distribution of secondary nucleoli among cells within each individual and among individuals from each population suggests that secondary NORs are activated according to an ordered hierarchy or nucleolar dominance. The existence of nucleolus-like structures during interkinesis-il and early round spermatids could indicate that NOR reactivation takes place at these stages. This NOR reactivation must depend on the secondary NORs, at least in the indivudals from the neo XY race of the species P. cucullata where half of the cells from meiosis-I on lack the neo X chromosome which carries the single primary NOR in this race.

show abstract

Section: Number and Location Of Active Norsmentioning

confidence: 53%

Section: Methodsmentioning

confidence: 99%

Section: The Chromosome Complementmentioning

confidence: 99%

See 1 more Smart Citation

Primary and secondary nucleolar organiser regions during spermatogenesis in the genus Pycnogaster

1988

View full text Add to dashboard Cite

show abstract

“…A drop of this solution was placed on the slide and incubated at 60°C in a moist chamber for variable (Sentis et a!., 1984).…”

Section: Methodsmentioning

confidence: 99%

The B chromosomes of Pycnogaster cucullata (Charp.) and their effects on the A complement

Sentís

Fernández‐Piqueras

1985

Heredity

View full text Add to dashboard Cite

Pycnogaster cucullata (Charp.) is a polytypic species of Tettigonioidea having XO and XV chromosomal races. In all populations of these races examined, several individuals were found carrying B chromosomes that may be of two morphological types, namely St and d. Although during diplotene the Bs appear almost completely condensed (positively heteropycnotic), and meiotic and mitotic metaphases only two grey intercalary C-bands can be shown. The utilisation of a silver impregnation method allowed us to distinguish the B-chromatin from the facultative heterochromatin of the neo X chromosomes, because both types of heterochromatin present a different condensation cycle during meiotic prophase. The presence of two Bs in nine individuals from the PEG population can be correlated with the simultaneous occurrence of several types of abnormalities affecting the A-chromosomes: spontaneous breakage, depression in the amount of effective pairing, germ line polysomy, endopolyploidy and micronuclei. These effects have also been observed in the individuals of PEG and another population carrying only one B but at a low frequency. While germ line polysomy may be essentially related to the presence and number of Bs (additive effect), determinant factors present in the genetic background cannot be excluded as contributing to the control of effective pairing.

show abstract

“…The species Pycnogaster cucullata has been studied in previous papers, and two cytological races were found differing by their sex chromosome system (XO and neo XY) (Fernández-Piqueras eta!., 1982, 1983SentIs et aL, 1984). Silver impregnation in spermatocytes of this species has also served to demonstrate two different categories of Ag-NORs, named primary and secondary, which differ by the appearance and meiotic behaviour of their silver precipitates.…”

Section: Introductionmentioning

confidence: 97%

Latent NORs in the species Pycnogaster cucullata (Orthoptera)

et al. 1990

View full text Add to dashboard Cite

The chromosomal location of the ribosomal cistrons 18 + 26S and 5S has been determined in spermatocytes of two cytological races of Pycnogaster cucullata by in situ hybridization using molecular probes from both types of rDNA. A comparative analysis with previous results suggested the existence of more 18+ 26S rDNA sites than active NORs as shown by silver impregnation, but 58 rDNA sites are outside the NORs. Thus, different categories of latent NORs have been shown in this specialised cell type which are discussed in relation to the evolutionary process of differentiation in this species.

show abstract

Morphology of the axial structures in the neo-XY sex bivalent of Pycnogaster cucullata (Orthoptera) by silver impregnation

Cited by 19 publications

References 19 publications

Primary and secondary nucleolar organiser regions during spermatogenesis in the genus Pycnogaster

Primary and secondary nucleolar organiser regions during spermatogenesis in the genus Pycnogaster

The B chromosomes of Pycnogaster cucullata (Charp.) and their effects on the A complement

Latent NORs in the species Pycnogaster cucullata (Orthoptera)

Contact Info

Product

Resources

About