Synaptic abnormalities in spread nuclei of Secale. II. Secale vavilovii

Genome ◽  
1995 ◽  
Vol 38 (4) ◽  
pp. 772-779 ◽  
Author(s):  
M. Martínez ◽  
C. Romero ◽  
C. Cuadrado
Keyword(s):  
Synaptonemal Complex ◽  
High Frequency ◽  
Diploid Species ◽  
Chromosome Complement ◽  
Nucleolar Organizer ◽  
Prophase I ◽  
Total Length ◽  
Metaphase I

Secale vavilovii PMCs have more univalents and a lower frequency of bound arms at metaphase I than other diploid Secale species. The spreading technique applied at prophase I showed that the nuclei were able to complete synapsis at pachytene. However, 25% of the nuclei analyzed, which had more than 90% of their total length paired, showed two abnormalities: long fold-back loops, which were located mainly on the nucleolar organizer bivalent, and pairing-partner switches, probably involving all the chromosome complement. These synaptic abnormalities are unusual in diploid species and give rise to a high frequency of nonhomologous pairing regions and, therefore, could produce desynapsis, which could explain the data obtained from metaphase I. The possible origin of the unusual synaptic abnormalities of S. vavilovii is discussed.Key words: S. vavilovii, synaptonemal complex, spreading, synaptic abnormalities.

Chromosome pairing and potential for intergeneric recombination in some hypotetraploid somatic hybrids of Lycopersicon esculentum (+) Solanum tuberosum

Genome ◽  
1993 ◽  
Vol 36 (6) ◽  
pp. 1032-1041 ◽  
Author(s):  
J. H. de Jong ◽  
A. M. A. Wolters ◽  
J. M. Kok ◽  
H. Verhaar ◽  
J. van Eden
Keyword(s):  
Solanum Tuberosum ◽  
Lycopersicon Esculentum ◽  
Synaptonemal Complex ◽  
Chromosome Pairing ◽  
Somatic Hybrids ◽  
Cytogenetic Study ◽  
Unreduced Gametes ◽  
Root Tip ◽  
Prophase I ◽  
Metaphase I

Three somatic hybrids resulting from protoplast fusions of a diploid kanamycin-resistant line of tomato (Lycopersicon esculentum) and a dihaploid hygromycin-resistant transformant of a monohaploid potato (Solanum tuberosum) line were used for a cytogenetic study on chromosome pairing and meiotic recombination. Chromosome counts in root-tip meristem cells revealed two hypotetraploids with chromosome complements of 2n = 46 and one with 2n = 47. Electron microscope analyses of synaptonemal complex spreads of hypotonically burst protoplasts at mid prophase I showed abundant exchanges of pairing partners in multivalents involving as many as eight chromosomes. In the cells at late pachytene recombination nodules were found in multivalents on both sides of pairing partner exchanges, indicating recombination at both homologous and homoeologous sites. Light microscope observations of pollen mother cells at late diakinesis and metaphase I also revealed multivalents, though their occurrence in low frequencies betrays the reduction of multivalent number and complexity. Precocious separation of half bivalents at metaphase I and lagging of univalents at anaphase I were observed frequently. Bridges, which may result from an apparent inversion loop found in the synaptonemal complexes of a mid prophase I nucleus, were also quite common at anaphase I, though the expected accompanying fragments could be detected in only a few cells. Most striking were the high frequencies of first division restitution in preparations at metaphase II/anaphase II, giving rise to unreduced gametes. In spite of the expected high numbers of balanced haploid and diploid gametes, male fertility, as revealed by pollen staining, was found to be negligible.Key words: synaptonemal complex, recombination, chromosome pairing, somatic hybrid, Lycopersicon esculentum (+) Solanum tuberosum.

A diploid surrounded by polyploids: tadpole description, natural history and cytogenetics of Odontophrynus maisuma Rosset from Uruguay (Anura: Cycloramphidae)

Zootaxa ◽  
2010 ◽  
Vol 2611 (1) ◽  
pp. 1 ◽  
Author(s):  
CLAUDIO BORTEIRO ◽  
FRANCISCO KOLENC ◽  
MARTÍN O. PEREYRA ◽  
SERGIO ROSSET ◽  
DIEGO BALDO
Keyword(s):  
Diploid Species ◽  
Chromosome Complement ◽  
Nucleolar Organizer ◽  
Dominant Frequency ◽  
Advertisement Call ◽  
Nucleolar Organizer Regions ◽  
Southern Brazil ◽  
Oral Disc ◽  
Erythrocyte Morphology ◽  
Single Row

Odontophrynus maisuma is a recently described diploid species of the diploid-tetraploid O. americanus complex. It inhabits coastal regions of Uruguay and southern Brazil. Tadpoles of O. maisuma at stages 33–36 are about 47 mm of total length, and similarly to that of other Odontophrynus are typical pond dwelling anuran larvae; the oral disc is small and laterally emarginated, bearing a single row of marginal papillae interrupted by a large dorsal gap. The labial tooth row formula is 2(2)/3(1); sometimes A2 and P1 are not divided. The advertisement call consists of notes that last 570– 785 ms, composed of 43–57 pulses, and with a dominant frequency between 1124–1211 Hz. The chromosome complement is composed by 11 biarmed chromosome pairs (2n = 2x = 22; NF = 44), with evident positive C-bands in the centromeric regions of all chromosome pairs, in the short arms of pairs 2 and 4, and in the long arms of pair 6 and 9. Nucleolar Organizer Regions (Ag-NORs) are located interstitially in the short arms of both chromosomes of pair 4. Preliminary data suggests that erythrocyte morphology could be used to discriminate between diploid and tetraploid tadpoles of Odontophrynus.

Differences in the synaptic pattern in two autotetraploid cultivars of rye with different quadrivalent frequencies at metaphase I

Genome ◽  
1999 ◽  
Vol 42 (4) ◽  
pp. 662-667
Author(s):  
M Martínez ◽  
C Cuadrado ◽  
J Sybenga ◽  
C Romero
Keyword(s):  
Electron Microscopy ◽  
Synaptonemal Complex ◽  
Prophase I ◽  
Quadrivalent Frequency ◽  
Surface Spread ◽  
Metaphase I

Synaptic behaviour of the two tetraploids rye cultivars Gigantón (G) and Tetrapico (T) displaying significant differences in their quadrivalent frequencies at metaphase I was analyzed by electron microscopy in surface-spread prophase I nuclei. A different behaviour was observed between the two cultivars; the synaptonemal complex (SC) quadrivalents frequency being significantly higher in G than in T at prophase I. Moreover, the G SC quadrivalents had more synaptic partner exchanges (SPEs) and their location was more distal than the T SC quadrivalents. However, inverse findings were found at metaphase I, the quadrivalent frequency was higher in T than in G. The role that different factors, mainly the number and location of the SPEs and the frequency and distribution of chiasmata, could play in the evolution from prophase I to metaphase I in both cultivars is discussed.Key words: autotetraploid rye, synaptonemal complex, spreading.

Chromosome pairing in the allotetraploid Aegilops biuncialis and a triploid intergeneric hybrid

Genome ◽  
1996 ◽  
Vol 39 (4) ◽  
pp. 664-670 ◽  
Author(s):  
N. Cuñado ◽  
S. Callejas ◽  
M. J. García ◽  
J. L Santos ◽  
A. Fernández
Keyword(s):  
Synaptonemal Complex ◽  
Chromosome Pairing ◽  
Complex Analysis ◽  
Intergeneric Hybrid ◽  
Chiasma Formation ◽  
Triploid Hybrid ◽  
Homologous Chromosomes ◽  
Prophase I ◽  
Surface Spread ◽  
Metaphase I

Chromosome pairing behaviour of the natural allotetraploid Aegilops biuncialis (genome UUMM) and a triploid hybrid Ae. biuncialis × Secale cereale (genome UMR) was analyzed by electron microscopy in surface-spread prophase I nuclei. Synaptonemal-complex analysis at zygotene and pachytene revealed that synapsis in the allotetraploid was mostly between homologous chromosomes, although a few quadrivalents were also formed. Only homologous bivalents were observed at metaphase I. In contrast, homoeologous and heterologous chromosome associations were common at prophase I and metaphase I of the triploid hybrid. It is concluded that the mechanism controlling bivalent formation in Ae. biuncialis acts mainly at zygotene by restricting pairing to homologous chromosomes, but also acts at pachytene by preventing chiasma formation in the homoeologous associations. In the hybrid the mechanism fails at both stages. Key words : Aegilops biuncialis, allotetraploid, intergeneric hybrid, pairing control, synaptonemal complex.

Normal Synaptonemal Complex and Abnormal Recombination Nodules in Two Alleles of the Drosophila Meiotic Mutant mei-W68

Genetics ◽  
2003 ◽  
Vol 163 (4) ◽  
pp. 1337-1356 ◽  
Author(s):  
Adelaide T C Carpenter
Keyword(s):  
Electron Microscopy ◽  
Synaptonemal Complex ◽  
High Frequency ◽  
Serial Section ◽  
The Other ◽  
Wild Type ◽  
Recombination Nodules ◽  
Section Electron ◽  
Serial Section Electron Microscopy ◽  
Section Electron Microscopy

Abstract The meiotic phenotypes of two mutant alleles of the mei-W68 gene, 1 and L1, were studied by genetics and by serial-section electron microscopy. Despite no or reduced exchange, both mutant alleles have normal synaptonemal complex. However, neither has any early recombination nodules; instead, both exhibit high numbers of very long (up to 2 μm) structures here named “noodles.” These are hypothesized to be formed by the unchecked extension of identical but much shorter structures ephemerally seen in wild type, which may be precursors of early recombination nodules. Although the mei-W68L1 allele is identical to the mei-W681 allele in both the absence of early recombination nodules and a high frequency of noodles (i.e., it is amorphic for the noodle phene), it is hypomorphic in its effects on exchange and late recombination nodules. The differential effects of this allele on early and late recombination nodules are consistent with the hypothesis that Drosophila females have two separate recombination pathways—one for simple gene conversion, the other for exchange.

scholarly journals The CSN/COP9 Signalosome Regulates Synaptonemal Complex Assembly during Meiotic Prophase I of Caenorhabditis elegans

PLoS Genetics ◽  
2014 ◽  
Vol 10 (11) ◽  
pp. e1004757 ◽  
Author(s):  
Heather Brockway ◽  
Nathan Balukoff ◽  
Martha Dean ◽  
Benjamin Alleva ◽  
Sarit Smolikove
Keyword(s):  
Caenorhabditis Elegans ◽  
Synaptonemal Complex ◽  
Meiotic Prophase ◽  
Cop9 Signalosome ◽  
Complex Assembly ◽  
Prophase I ◽  
Meiotic Prophase I

Synaptonemal complex proteins: occurrence, epitope mapping and chromosome disjunction

1994 ◽  
Vol 107 (10) ◽  
pp. 2749-2760 ◽  
Author(s):  
M.J. Dobson ◽  
R.E. Pearlman ◽  
A. Karaiskakis ◽  
B. Spyropoulos ◽  
P.B. Moens
Keyword(s):  
Synaptonemal Complex ◽  
Fusion Proteins ◽  
Epitope Mapping ◽  
Core Protein ◽  
Binding Capacity ◽  
Polyclonal Antibodies ◽  
Meiotic Chromosome ◽  
Immunogold Labelling ◽  
Chromosome Disjunction ◽  
Metaphase I

We have used polyclonal antibodies against fusion proteins produced from cDNA fragments of a meiotic chromosome core protein, Cor1, and a protein present only in the synapsed portions of the cores, Syn1, to detect the occurrence and the locations of these proteins in rodent meiotic prophase chromosomes. The 234 amino acid Cor1 protein is present in early unpaired cores, in the lateral domains of the synaptonemal complex and in the chromosome cores when they separate at diplotene. A novel observation showed the presence of Cor1 axial to the metaphase I chromosomes and substantial amounts of Cor1 in association with pairs of sister centromeres. The centromere-associated Cor1 protein becomes dissociated from the centromeres at anaphase II and it is not found in mitotic metaphase centromeres. The extended presence of Cor1 suggests that it may have a role in chromosome disjunction by fastening chiasmata at metaphase I and by joining sister kinetochores, which ensures co-segregation at anaphase I. Two-colour immunofluorescence of Cor1 and Syn1 demonstrates that synapsis between homologous cores is initiated at few sites but advances rapidly relative to the establishment of new initiation sites. If the rapid advance of synapsis deters additional initiation sites between pairs of homologues, it may provide a mechanism for positive recombination interference. Immunogold epitope mapping of antibodies to four Syn1 fusion proteins places the amino terminus of Syn1 towards the centre of the synaptonemal complex while the carboxyl terminus extends well into the lateral domain of the synaptonemal complex. The Syn1 fusion proteins have a non-specific DNA binding capacity. Immunogold labelling of Cor1 antigens indicates that the lateral domain of the synaptonemal complex is about twice as wide as the apparent width of lateral elements when stained with electron-dense metal ions. Electron microscopy of shadow-cast surface-spread SCs confirms the greater width of the lateral domain. The implication of these dimensions is that the proteins that comprise the synaptic domain overlap with the protein constituents of the lateral domains of the synaptonemal complex more than was apparent from earlier observations. This arrangement suggests that direct interactions might be expected between some of the synaptonemal complex proteins.

Taxonomic status of male salamanders of the Ambystoma jeffersonianum complex from an Ontario population, with the first record of the Jefferson salamander, A. jeffersonianum (Green), from Canada

1976 ◽  
Vol 54 (8) ◽  
pp. 1270-1276 ◽  
Author(s):  
Wayne F. Weller ◽  
W. Gary Sprules
Keyword(s):  
Diploid Species ◽  
Taxonomic Status ◽  
Tail Length ◽  
First Record ◽  
Total Length ◽  
Ambystoma Jeffersonianum ◽  
Morphological Criteria ◽  
G Ratio ◽  
Jefferson Salamander

Nine morphological criteria were used to determine the taxonomic status of the male salamanders of the Ambystoma jeffersonianum complex from a population near Streetsville, Toronto Township, Peel County, Ontario: (a) snout–vent length; (b) ratio of tail length to snout–vent length; (c) internarial width; (d) extent of separation or overlap of the toes of adpressed limbs; (e) total length; (f) ratio of tail length to total length; (g) ratio of internarial width to snout–vent length; (h) colouration of dorsal, lateral, and ventral body surfaces; and, (i) extent and distribution of the bluish spotting. The results indicate that all of these males resemble A. jeffersonianum or A. platineum rather than A. latérale. Since A. platineum males occur very rarely in nature, these Streetsville individuals are logically assigned to A. jeffersonianum. This represents the first record of this species from Canada. Based upon this new distributional datum of A. jeffersonianum and of the two Diploid species from the literature, we suggest that these triploid species may have originated in post-Wisconsin times and subsequently dispersed northward.

Pattern of X-Y chromosome pairing in the Taiwan vole, Microtus kikuchii

Genome ◽  
2001 ◽  
Vol 44 (1) ◽  
pp. 27-31 ◽  
Author(s):  
K Mekada ◽  
M Harada ◽  
L K Lin ◽  
K Koyasu ◽  
P M Borodin ◽  
...  
Keyword(s):  
Synaptonemal Complex ◽  
Chromosome Pairing ◽  
Sex Chromosomes ◽  
Meiotic Prophase ◽  
Organizer Region ◽  
Nucleolar Organizer Region ◽  
Nucleolar Organizer ◽  
The Other ◽  
Banding Patterns ◽  
Y Chromosomes

Pairing of X and Y chromosomes at meiotic prophase and the G- and C-banding patterns and nucleolar organizer region (NOR) distribution were analyzed in Microtus kikuchii. M. kikuchii is closely related to M. oeconomus and M. montebelli, karyologically and systematically. The formation of a synaptonemal complex between the X and Y chromosomes at pachytene and end-to-end association at diakinesis – metaphase I are only observed in three species in the genus Microtus; M. kikuchii, M. oeconomus, and M. montebelli. All the other species that have been studied so far have had asynaptic X–Y chromosomes. These data confirm that M. kikuchii, M. oeconomus, and M. montebelli are very closely related, and support the separation of asynaptic and synaptic groups on the phylogenetic tree.Key words: Microtus kikuchii, Microtus phylogeny, karyotype, synaptic sex chromosomes, synaptonemal complex.

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