Synaptonemal complex analysis in spermatocytes of tilapia, Oreochromis niloticus (Pisces, Cichlidae)

Genome ◽  
1993 ◽  
Vol 36 (6) ◽  
pp. 1124-1128 ◽  
Author(s):  
Fausto Foresti ◽  
Claudio Oliveira ◽  
Pedro Manoel Galetti Junior ◽  
Lurdes Foresti de Almeida-Toledo
Keyword(s):  
Synaptonemal Complex ◽  
Sex Chromosomes ◽  
Oreochromis Niloticus ◽  
Complex Analysis ◽  
Sex Chromosome ◽  
Light And Electron Microscopy ◽  
Nucleolus Organizer ◽  
Nucleolus Organizer Regions ◽  
Synaptonemal Complex Analysis ◽  
Sex Chromosome System

Some adaptations of the synaptonemal complex (SC) whole-mounting technique first used in plants permitted its application to meiotic studies in tilapia, Oreochromis niloticus. Direct observation of the chromosome pairing process and bivalent structure during the meiotic prophase of this fish species by light and electron microscopy permitted the analysis of SCs in autosomes and the possible identification of sex chromosomes. The analysis of SCs in spermatocytes of O. niloticus revealed that all 22 bivalent chromosomes completely paired, except for the occurrence of a size heteromorphism in the terminal region of the largest bivalent associated with the presence of an incompletely paired segment during the synapsis process, which may be the cytological visualization of an XX/XY sex chromosome system in this species.Key words: fish cytogenetics, synaptonemal complex, fish meiosis, sex chromosomes, nucleolus organizer regions.

Synaptonemal Complex Analysis of Sex Chromosomes in Two Species of Sceloporus

Copeia ◽  
1990 ◽  
Vol 1990 (4) ◽  
pp. 1122 ◽  
Author(s):  
Kent M. Reed ◽  
Philip D. Sudman ◽  
Jack W. Sites ◽  
Ira F. Greenbaum
Keyword(s):  
Synaptonemal Complex ◽  
Sex Chromosomes ◽  
Complex Analysis ◽  
Synaptonemal Complex Analysis

scholarly journals Whole-chromosome fusions in the karyotype evolution of Sceloporus (Iguania, Reptilia) are more frequent in sex chromosomes than autosomes

2021 ◽  
Vol 376 (1833) ◽  
pp. 20200099
Author(s):  
Artem P. Lisachov ◽  
Katerina V. Tishakova ◽  
Svetlana A. Romanenko ◽  
Anna S. Molodtseva ◽  
Dmitry Yu. Prokopov ◽  
...  
Keyword(s):  
Sex Chromosomes ◽  
Recombination Rate ◽  
Complex Analysis ◽  
Chromosome Evolution ◽  
Sex Chromosome ◽  
Comparative Genomic ◽  
Synaptonemal Complex Analysis ◽  
Chromosome Fusions ◽  
Chromosome Formation ◽  
Pseudoautosomal Regions

Whole-chromosome fusions play a major role in the karyotypic evolution of reptiles. It has been suggested that certain chromosomes tend to fuse with sex chromosomes more frequently than others. However, the comparative genomic synteny data are too scarce to draw strong conclusions. We obtained and sequenced chromosome-specific DNA pools of Sceloporus malachiticus , an iguanian species which has experienced many chromosome fusions. We found that four of seven lineage-specific fusions involved sex chromosomes, and that certain syntenic blocks which constitute the sex chromosomes, such as the homologues of the Anolis carolinensis chromosomes 11 and 16, are repeatedly involved in sex chromosome formation in different squamate species. To test the hypothesis that the karyotypic shift could be associated with changes in recombination patterns, we performed a synaptonemal complex analysis in this species and in Sceloporus variabilis (2 n = 34). It revealed that the sex chromosomes in S. malachiticus had two distal pseudoautosomal regions and a medial differentiated region. We found that multiple fusions little affected the recombination rate in S. malachiticus . Our data confirm more frequent involvement of certain chromosomes in sex chromosome formation, but do not reveal a connection between the gonosome–autosome fusions and the evolution of recombination rate. This article is part of the theme issue ‘Challenging the paradigm in sex chromosome evolution: empirical and theoretical insights with a focus on vertebrates (Part II)’.

Ultrastructural analysis of the X1X2X3O sex chromosome system during the spermatogenesis of Tegenaria domestica (Arachnida)

1982 ◽  
Vol 58 (1) ◽  
pp. 411-422
Author(s):  
R. Benavente ◽  
R. Wettstein ◽  
M. Papa
Keyword(s):  
Synaptonemal Complex ◽  
Chromosome Pairing ◽  
Sex Chromosomes ◽  
Ultrastructural Study ◽  
Chromosome Structure ◽  
Sex Chromosome ◽  
X Chromosomes ◽  
Sex Chromosome System ◽  
Available Information ◽  
Dense Chromatin

An ultrastructural study was performed on the sex chromosomes (male X1X2X3O) during the spermatogenesis of Tegenaria domestica (Arachnida, Agelenidae). This study was carried out using random and serially cut sections. During pachytene and diplotene the three X chromosomes are longitudinally paired. Each of these consists of a central core of condensed chromatin, surrounded by a field of dense chromatin projections through which the chromosomes are in contact with one another. These projections may be responsible for the recognition and pairing of the sex chromosomes and in some way participate in their non-disjunction during anaphase I. A study of the structure and behaviour of the sex chromosomes during spermatogenesis is also presented. The available information on non-synaptonemal complex-mediated chromosome pairing and a systematization of sex chromosome structure in spiders are discussed.

scholarly journals Karyotype description and evidence of multiple sex chromosome system X1X1X2X2/X1X2Y in Potamotrygon aff. motoro and P. falkneri (Chondrichthyes: Potamotrygonidae) in the upper Paraná River basin, Brazil

2011 ◽  
Vol 9 (1) ◽  
pp. 201-208 ◽  
Author(s):  
Vanessa Paes da Cruz ◽  
Cristiane Kioko Shimabukuro-Dias ◽  
Claudio Oliveira ◽  
Fausto Foresti
Keyword(s):  
Sex Chromosome ◽  
Chromosomal Rearrangements ◽  
Chromosomal Evolution ◽  
Nucleolus Organizer ◽  
Banding Technique ◽  
Nucleolus Organizer Regions ◽  
Sex Chromosome System ◽  
Upper Paraná River ◽  
Upper Paraná River Basin ◽  
Almost All

Cytogenetic analysis of Potamotrygon aff. motoro and P. falkneri indicated the occurrence of an X1X1X2X2/X1X2 Y multiple sex chromosome system in both species, with 2n = 66 chromosomes for females and 2n = 65 chromosomes for males. The nucleolus organizer regions (NORs) identified using Ag-NOR technique showed that both species have multiple Ag-NORs (5 to 7 chromosomes stained). C-banding technique indicated the presence of heterochromatic blocks in the centromeric regions of almost all chromosomes in both species. Through this study there was evidence of heterogeneity in the karyotypes, which suggests that chromosomal rearrangements such as inversions and/or translocations occurred during the chromosomal evolution in two species of this genus.

Genomic Organization of Repetitive DNAs and Differentiation of an XX/XY Sex Chromosome System in the Amazonian Puffer Fish, Colomesus asellus (Tetraodontiformes)

2017 ◽  
Vol 153 (2) ◽  
pp. 96-104 ◽  
Author(s):  
Patrik F. Viana ◽  
Tariq Ezaz ◽  
Leandro Marajó ◽  
Milena Ferreira ◽  
Jansen Zuanon ◽  
...  
Keyword(s):  
Y Chromosome ◽  
Sex Chromosome ◽  
First Record ◽  
Nucleolus Organizer ◽  
X Chromosomes ◽  
Nucleolus Organizer Regions ◽  
Rdna Sites ◽  
Puffer Fish ◽  
Specific Amplification ◽  
Sex Chromosome System

The genus Colomesus is the sole representative of the family Tetraodontidae in the Amazon region. Here, Colomesus asellus was analyzed using conventional and molecular cytogenetic protocols. Its diploid chromosome number is 2n = 46 with 12 meta-, 10 submeta-, 16 subtelo-, and 8 acrocentric chromosomes and a fundamental number of FN = 84. An XX/XY sex chromosome system was identified. Mapping of 18S rDNA correlated with the nucleolus organizer regions (Ag-NORs) in the short arms of the 2 X chromosomes in females and in the Y chromosome in males. C-banding revealed heterochromatin in the centromeric regions of all chromosomes, except for pair 3. Prominent sex chromosome-specific heterochromatin amplification was observed, covering the short arms of the Y chromosome almost entirely. FISH with telomeric and tropomyosin (tpm1) sequences, respectively, revealed terminal signals in all chromosomes. The analysis of extended DNA fibers confirmed the colocalization and the interspersed pattern of the telomeric and tpm1 sequences. Thus, this study highlights the remarkable evolutionary dynamism presented by the Amazonian puffer fish regarding the differentiation of a heteromorphic XY sex chromosome system and a particular sex-specific amplification of rDNA sites. This is the first record of such an association in the Tetraodontidae family.

Synaptonemal complex analysis of mole rats (Spalax ehrenbergi): unusual polymorphisms of chromosome

Genome ◽  
1990 ◽  
Vol 33 (6) ◽  
pp. 898-902 ◽  
Author(s):  
Ira F. Greenbaum ◽  
David W. Hale ◽  
Philip D. Sudman ◽  
Eviatar Nevo
Keyword(s):  
Synaptonemal Complex ◽  
Complex Analysis ◽  
Chromosomal Polymorphism ◽  
Nucleolus Organizer ◽  
Intraindividual Variation ◽  
Spalax Ehrenbergi ◽  
Mole Rat ◽  
Chromosomal Pair ◽  
Synaptonemal Complex Analysis ◽  
Surface Spread

Two unusual structural polymorphisms in the largest chromosomal pair of the Israeli mole rat, Spalax ehrenbergi, were analyzed from surface-spread and silver-stained preparations of synaptonemal complexes. A C-band negative polymorphism for the length of the 1p arm was visible as axial length differences during late zygonema and early pachynema. This region underwent synaptic adjustment resulting in a fully paired, mid-pachytene synaptonemal complex with equalized axial lengths. The somatically variable and nonargentophilic secondary constriction in the 1q arm was evident as a distinct silver-stained thickening along the synaptonemal complex. Presence of this structure on the synaptonemal complex varied both among individuals and among cells within individuals. The intraindividual variation of this region is hypothesized to represent differential biochemical activity with its cellular visualization being regulated in a manner similar to that of nucleolus organizer regions.Key words: mole rats, synaptonemal complex, chromosomal polymorphism.

scholarly journals Whole-chromosome fusions in the karyotype evolution of Sceloporus (Iguania, Reptilia) are more intense in sex chromosomes than autosomes

2020 ◽  
Author(s):  
Artem P. Lisachov ◽  
Katerina V. Tishakova ◽  
Svetlana A. Romanenko ◽  
Anna S. Molodtseva ◽  
Dmitry Yu. Prokopov ◽  
...  
Keyword(s):  
Sex Chromosomes ◽  
Complex Analysis ◽  
Sex Chromosome ◽  
Chromosome 11 ◽  
Evolutionary Forces ◽  
Chromosome Synapsis ◽  
Synaptonemal Complex Analysis ◽  
Chromosome Fusions ◽  
Chromosome Formation ◽  
Pseudoautosomal Regions

AbstractThere is a growing body of evidence that the common ancestor of vertebrates had a bimodal karyotype, i.e. consisting of large macrochromosomes and small microchromosomes. This type of karyotype organization is preserved in most reptiles. However, certain species independently experience microchromosome fusions. The evolutionary forces behind this are unclear. We investigated the karyotype of the green spiny lizard, Sceloporus malachiticus, an iguana species which has 2n=22, whereas the ancestral karyotype of iguanas had 2n=36. We obtained and sequenced flow-sorted chromosome-specific DNA samples and found that most of the microchromosome fusions in this species involved sex chromosomes. We found that certain ancestral squamate chromosomes, such as the homologue of the Anolis carolinensis chromosome 11, are repeatedly involved in sex chromosome formation in different species. To test the hypothesis that the karyotypic shift could be associated with changes in recombination patterns, and to study sex chromosome synapsis and recombination in meiosis, we performed synaptonemal complex analysis in this species and in S. variabilis, a related species with 2n=34. We found that in the species studied the recombination patterns correlate more with phylogeny than with the structure of the karyotype. The sex chromosomes had two distal pseudoautosomal regions and a medial differentiated region.

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