Synaptonemal complex analysis in spermatocytes and oocytes of rainbow trout,Oncorhynchus mykiss (Pisces, Salmonidae): the process of autosome and sex chromosome synapsis

1995 ◽  
Vol 3 (3) ◽  
pp. 182-190 ◽  
Author(s):  
Claudio Oliveira ◽  
Fausto Foresti ◽  
Marcos Guilherme Rigolino ◽  
Yara Aiko Tabata
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Synaptonemal Complex ◽  
Complex Analysis ◽  
Sex Chromosome ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Chromosome Synapsis ◽  
Synaptonemal Complex Analysis

Synaptonemal complex analysis in spermatocytes of white sturgeon, Acipenser transmontanus Richardson (Pisces, Acipenseridae), a fish with a very high chromosome number

Genome ◽  
1998 ◽  
Vol 41 (1) ◽  
pp. 51-61 ◽  
Author(s):  
A L Van Eenennaam ◽  
J D Murray ◽  
J F Medrano
Keyword(s):  
Chromosome Number ◽  
Synaptonemal Complex ◽  
Complex Analysis ◽  
White Sturgeon ◽  
Chromosome Synapsis ◽  
Heteromorphic Sex Chromosomes ◽  
Synaptonemal Complex Analysis ◽  
Pairing Behavior ◽  
Heterogametic Sex ◽  
Surface Spreading

The surface-spreading synaptonemal complex (SC) technique was used to visualize the process of chromosome synapsis in white sturgeon spermatocytes. Pachytene nuclei had various numbers of univalents (0-3) and self-paired foldback elements with no obvious centromeric region (1-7) that may represent accessory chromosomes. The total SC length was 482 ( ±56) µm and the average number of SC elements per nucleus was 139 ( ±3.4). This SC number suggests a higher chromosome number than had been reported in previous mitotic studies (2n = 248 ± 8). There was variation in the SC count both within and between animals. A representative SC karyotype is presented and some differences between the mitotic and meiotic karyotypes for this species are discussed. There was no evidence of multivalent formation, suggesting that the process of diploidization has gone to completion in the males of this ancient polyploid species. Each SC had lateral elements of equal length, and no bivalent exhibited the atypical pairing behavior that is often characteristically associated with heteromorphic sex chromosomes, suggesting that the male is not the heterogametic sex in white sturgeon.

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.

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.

Synaptonemal complex analysis in spermatocytes and oocytes of turbot, Scophthalmus maximus (Pisces, Scophthalmidae)

Genome ◽  
2001 ◽  
Vol 44 (6) ◽  
pp. 1143-1147 ◽  
Author(s):  
N Cuñado ◽  
J Terrones ◽  
L Sánchez ◽  
P Martínez ◽  
J L Santos
Keyword(s):  
Synaptonemal Complex ◽  
Dna Content ◽  
Complex Analysis ◽  
Scophthalmus Maximus ◽  
Chromosome Synapsis ◽  
Content Ratio ◽  
Bony Fishes ◽  
Heteromorphic Sex Chromosomes ◽  
Synaptonemal Complex Analysis ◽  
Turbot Scophthalmus Maximus

A surface-spreading synaptonemal complex (SC) technique was used to analyze spermatocytes and oocytes of turbot (Scophthalmus maximus) to visualize the process of chromosome synapsis. The total SC length was 205 ± 12 µm in males and 172 ± 29 µm in the only female analyzed. A representative SC karyotype of turbot was obtained. Each SC showed lateral elements of equal length. No bivalent exhibiting atypical synaptic behaviour that could be associated with heteromorphic sex chromosomes was observed, either in males or in the female. The DNA content of turbot was evaluated in eight individuals of both sexes by flow cytometry analysis. The 2C mean DNA content of turbot (1.308 ± 0.009 pg/cell) was among the lowest observed within fishes. No statistical differences in DNA content were revealed between the sexes [Wilcoxon/Mann–Whitney test; P(Wx = 0.243)]. The SC/DNA content ratio observed in turbot was the highest reported to date in bony fishes (Osteichthyes).Key words: Scophthalmus maximus, fish, DNA content, meiosis, synaptonemal complex.

Sex chromosome linkage of 5S rDNA in rainbow trout (Oncorhynchus mykiss)

1996 ◽  
Vol 75 (2-3) ◽  
pp. 145-150 ◽  
Author(s):  
P. Moran ◽  
J.L. Martinez ◽  
E. Garcia-Vazquezm ◽  
A.M. Pendas
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Sex Chromosome ◽  
5S Rdna ◽  
Rainbow Trout Oncorhynchus Mykiss
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