Chiasmata and recombination nodules in Lilium longiflorum

Genome ◽  
1989 ◽  
Vol 32 (3) ◽  
pp. 486-498 ◽  
Author(s):  
Stephen M. Stack ◽  
Lorinda K. Anderson ◽  
Jamie D. Sherman
Keyword(s):  
Synaptonemal Complex ◽  
Average Length ◽  
Central Element ◽  
Lilium Longiflorum ◽  
Uranyl Acetate ◽  
Synaptonemal Complexes ◽  
Recombination Nodules ◽  
Acetate Lead ◽  
Complete Set ◽  
Late Diplotene

We determined the frequency of chiasmata at late diplotene in microsporocytes of Lilium longiflorum (lily). Because there are long, intimate associations of homologous chromosomes in addition to short associations that appear to be single chiasmata, the number of chiasmata counted depends on how the long associations are interpreted. Using a defined method, we determined that there was an average of 54.8 ± 6.0 chiasmata per complete set of diplotene bivalents. Recombination nodules are 100-nm ellipsoids that are found on the central element of synaptonemal complexes. There is correlative evidence that strongly indicates recombination nodules are located at the sites of crossing-over in late pachytene. Using spreads of synaptonemal complexes stained with uranyl acetate – lead citrate, we determined that the frequency of recombination nodules was 1/57.2 μm of synaptonemal complex. Using separate silver-stained spreads of synaptonemal complexes from lily microsporocytes, we determined that the average length of a complete set of pachytene synaptonemal complexes was 3149 ± 668 μm. Therefore, an average set of synaptonemal complexes would have 55.1 (3149 ÷ 57.2) recombination nodules, a number that closely matches the average number of chiasmata in a set of late diplotene bivalents.Key words: chiasmata, recombination nodules, synaptonemal complex, Lilium longiflorum.

KARYOTYPE, SYNAPTONEMAL COMPLEXES AND POSSIBLE RECOMBINATION NODULES OF THE OOMYCETE FUNGUS SAPROLEGNIA

1982 ◽  
Vol 24 (4) ◽  
pp. 385-396 ◽  
Author(s):  
Kenji Tanaka ◽  
I. Brent Heath ◽  
Peter B. Moens
Keyword(s):  
Synaptonemal Complex ◽  
Nuclear Dna ◽  
Central Element ◽  
Nuclear Dna Content ◽  
Mean Value ◽  
Synaptonemal Complexes ◽  
Recombination Nodules ◽  
Section Electron ◽  
Serial Section Electron Microscopy ◽  
Complex Length

Pachytene nuclei of the fungus Saprolegnia ferax (Gruith.) Thuret were analyzed by serial section electron microscopy. These nuclei contained 21 synaptonemal complexes, all of which terminated at both ends on the nuclear envelope. These complexes range from 1.6 μm to 5.5 μm in length and are composed of two rather diffuse lateral elements, lack a continuous central element and contain discontinuous central nodes. These nodes occur at about 1 per μm of synaptonemal complex length, have a diameter of approximately 50 nm, are predominantly short (<200 nm) and appear to occur as multiples of a basic 50 nm length. These nodes are in many respects similar to previously reported recombination nodules. The complexes were not seen to form a bouquet stage. Based on nuclear DNA content and synaptonemal complex length, the chromosomes are calculated to contain 2C values of between 5.2 and 17.3 fg of DNA, with a mean value of 9.3 fg. Thus it seems that Saprolegnia has large chromosomes relative to other fungi and a haploid complement of 21.

The synaptonemal complexes of Achlya recurva (Oomycetes): karyotype analysis and three-dimensional reconstruction of pachytene nuclei in antheridia and oogonia

1991 ◽  
Vol 69 (6) ◽  
pp. 1384-1395 ◽  
Author(s):  
Hobart R. Williamson ◽  
Pesach Ben Yitzchak
Keyword(s):  
Synaptonemal Complex ◽  
Organizer Region ◽  
Nucleolar Organizer Region ◽  
Nucleolus Organizer Region ◽  
Three Dimensional ◽  
Central Element ◽  
Three Dimensional Reconstruction ◽  
Synaptonemal Complexes ◽  
Sequence Of Events ◽  
Dimensional Reconstruction

Fifteen synaptonemal complexes, as determined by three-dimensional reconstruction of serial, ultrathin sections, were present within both antheridial and oogonial zygotene and pachytene nuclei of the oomyceteous fungus Achlya recurva, thus n = 15. The present study represents the first complete reconstruction of synaptonemal complexes in the genus Achlya. The occurrence of both zygonema and pachynema was simultaneous in antheridia and oogonia. Pachytene nuclei of antheridia and oogonia are small, 13 μm3 in volume, and the average length of the synaptonemal complexes ranged from 1.9 to 4.4 μm. Lateral elements at zygotene ranged from 1.2 to 4.7 μm. Both ends of each synaptonemal complex were attached randomly to the nuclear envelope, so a bouquet formation was not observed at pachytene. In A. recurva, the dimensions of the synaptonemal complex were as follows: overall width = 270 nm; the lateral elements = 75 nm each in width and the central region = 120 nm. There was no central element and associated transverse filaments, which may be associated with development of alternative reproductive strategies other than amphimixis, as in nematodes. Of the 15 synaptonemal complexes present, only the one carrying the nucleolus organizer region could be clearly identified from one nucleus to the next. The nucleolar organizer region was on the average 0.75 μm from the telomere in both zygotene and pachytene nuclei. There were an average of three recombination nodules in each nucleus. Synaptonemal complexes have been reported in over 80 different species of fungi and related protista. Karyotypic evolution in the oomycetes and fungi may be the result of poly-ploidization, followed by cytogenetic diversification involving aneuploidy and differing degrees of polyploidy. Such a sequence of events could explain the apparent polyphyletic formation of this group. Key words: karyotype, Oomycetes, pachytene, synaptonemal complexes, three-dimensional reconstruction.

Recombination nodule mapping and chiasma distribution in spermatocytes of the pigeon, Columba livia

Genome ◽  
1999 ◽  
Vol 42 (2) ◽  
pp. 308-314 ◽  
Author(s):  
M I Pigozzi ◽  
A J Solari
Keyword(s):  
Synaptonemal Complex ◽  
Random Distribution ◽  
Phosphotungstic Acid ◽  
Columba Livia ◽  
Complex Karyotype ◽  
Synaptonemal Complexes ◽  
Recombination Nodules ◽  
Chiasma Distribution ◽  
The Mean ◽  
Good Agreement

Pigeon spermatocytes were processed with a drying-down technique and their synaptonemal complex (SC) complements were analyzed by electron microscopy. The synaptonemal complex karyotype of the macrobivalents shows an excellent correspondence with the mitotic karyotype. The number and distribution of recombination nodules (RNs) were scored in complete nuclei stained with phosphotungstic acid. The average number of RNs per nucleus is 64.7. The number of nodules per bivalent shows a clear linear relationship with SC length in the 10 longest synaptonemal complexes, while the microbivalents usually bear a single RN. The location of RNs has a non-random distribution along the largest synaptonemal complexes, with lower frequencies near kinetochores and higher frequencies toward the telomeres. The ZZ bivalent is the fourth in size and shows free recombination, having on average 3.8 RNs. The mean number of nodules per cell and the mean number of nodules in the largest bivalents show very good agreement with the corresponding number of chiasmata scored in metaphase-I spermatocytes. It is concluded that the recombination nodules provide a good check for reciprocal exchanges in this and other species of birds. Additionally, a new morphology for the recombination nodules is presented, consisting of groups of electron-dense particles measuring 43 nm in diameter.Key words: meiosis, chiasmata, recombination nodules, pigeon spermatogenesis.

Dependence on genie balance for synaptonemal complex formation in Drosophila melanogaster

Genome ◽  
1988 ◽  
Vol 30 (2) ◽  
pp. 258-264 ◽  
Author(s):  
T. M. Grishayeva ◽  
Y. F. Bogdanov
Keyword(s):  
Drosophila Melanogaster ◽  
Synaptonemal Complex ◽  
X Chromosome ◽  
Central Element ◽  
Sharp Decrease ◽  
Electron Microscopic Examination ◽  
Electron Microscopic ◽  
X Chromosomes ◽  
Ovary Cells ◽  
Synaptonemal Complexes

Electron microscopic examination of gonads of Drosophila melanogaster with different genotypes, including a metafemale 3X;2A and an intersex XXY;3A, have revealed that the formation of synaptonemal complexes is controlled by the genie balance, i.e., the ratio of X chromosomes to autosomes. The Y chromosome is not involved in the genetic control of the formation of precursors of the central element of synaptonemal complexes in males, nor does it disturb their formation in [Formula: see text] females. Hyperploidy for sections 1 – 3A and 18A – 20 of the X chromosome does not lead to the appearance of synaptonemal complexes in males and does not interfere with their formation in females. Females hyperploid for extensive regions of the X chromosome (sections 1 – 11A, 11A – 20, and 8C – 20) are fertile and show apparently normal formation of synaptonemal complexes. Hyperploidy for sections 8C – 11A of the X results in a sharp decrease in the viability of females, in abnormal differentiation of ovary cells, and in the lack of synaptonemal complexes. These data suggest a possible important role for the sections 8C – 11A in the genic balance controlling the formation of synaptonemal complexes in D. melanogaster. The lack of synaptonemal complexes in hypoploid females may be the result of abnormal cell differentiation in gonads.Key words: Drosophila melanogaster, synaptonemal complex, sex chromosomes, genic balance.

Localized chiasmata and meiotic nodules in the tetraploid onion Allium porrum

Genome ◽  
1996 ◽  
Vol 39 (4) ◽  
pp. 770-783 ◽  
Author(s):  
Stephen M. Stack ◽  
Dick Roelofs
Keyword(s):  
Key Words ◽  
Synaptonemal Complex ◽  
Allium Porrum ◽  
Crossing Over ◽  
High Fertility ◽  
Unusual Behavior ◽  
Synaptonemal Complexes ◽  
Recombination Nodules ◽  
Metaphase I

Allium porrum L. (cultivated leek) (2n = 4x = 32) is a fertile tetraploid that forms bivalents with pericentric chiasmata at metaphase I. To investigate the basis of this unusual behavior for a tetraploid, we describe the karyotype, axial cores, synaptonemal complexes (SCs), and meiotic nodules of A. porrum. The karyotype appears to be autotetraploid. This conclusion is also supported by presynaptic alignment of axial cores in groups of four and partner trades between pairs of SCs. Numerous early nodules are distributed all along axial cores and SCs during zygonema, but they are lost by late zygonema – early pachynema. Late (recombination) nodules (RNs) are present on SCs near kinetochores throughout the remainder of pachynema. This pattern of RNs corresponds to the pattern of pericentric chiasmata. Pachytene quadrivalents usually are resolved into bivalents because partner trades between SC lateral elements rarely occur between RNs on the same segment of SC. Thus, the patterns of crossing-over and partner trades promote balanced disjunction and high fertility in autotetraploid A. porrum. Rare quadrivalents observed at metaphase I must be due to infrequent partner trades between RNs. Polycomplexes, unusual in their number and size, were observed during zygonema. Key words : synaptonemal complex, recombination nodules, localized chiasmata, polycomplex, Allium porrum.

The synaptonemal complex karyotype from spread spermatocytes of a dipteran (Aedes aegypti)

1983 ◽  
Vol 25 (4) ◽  
pp. 361-369 ◽  
Author(s):  
Annelise Wandall ◽  
Allan Svendsen
Keyword(s):  
Electron Microscope ◽  
Aedes Aegypti ◽  
Light Microscopy ◽  
Synaptonemal Complex ◽  
Complex Karyotype ◽  
Synaptonemal Complexes ◽  
Recombination Nodules ◽  
The One ◽  
Mitotic Cells

Synaptonemal complexes (SCs) from the spermatocytes of the mosquito, Aedes aegypti, were spread on a 0.3 M sucrose hypophase and analyzed in the electron microscope. The SC karyotype was similar to the one known from light microscopy of mitotic cells in both relative lengths and in centromere positions. All pachytene nuclei retained their bouquet configuration during spreading; the telomeres were polarized and clustered, and the three centromeric regions were close together. The kinetochores differentiated during pachytene, those of bivalent No. 1 (the sex bivalent) before the others. Recombination nodules were preserved in some spreads; out of 35 nodules, whose distal or proximal location on the SC arms could be determined, 27 were located in the distal one-third of the arms. No SC arm had more than one nodule.

Synaptonemal complexes of triploid (ZZW) chickens: Z–Z pairing predominates over Z–W pairing

Genome ◽  
1991 ◽  
Vol 34 (5) ◽  
pp. 718-726 ◽  
Author(s):  
Alberto J. Solari ◽  
M. H. Thorne ◽  
B. L. Sheldon ◽  
C. B. Gillies
Keyword(s):  
Synaptonemal Complex ◽  
Central Region ◽  
Sex Chromosomes ◽  
W Chromosome ◽  
Synaptonemal Complexes ◽  
Early Pachytene ◽  
Recombination Nodule ◽  
Recombination Nodules ◽  
Central Regions ◽  
Partial Elimination

Twelve triploid, ZZW chickens of ages ranging from day 19 of incubation to 15 days after hatching were used for oocyte analysis. Oocytes show 117 axes per nucleus. At early pachytene, most axes form double synaptonemal complexes (triplets). An average of 27 triplets, 12 bivalents, and 12 univalents was observed. Later, a partial elimination of triplets occurs, as they are converted into typical trivalents or bivalents and univalents. The number of recombination nodules per nucleus (52.7) is similar to that of diploids. These nodules can occur in register in both central regions of a triplet (no lateral interference), and they probably stabilize the central region. Among 31 oocytes, 29 had a regular ZZ bivalent and a W univalent, and only 2 had triple pairing between a ZZ bivalent and a terminal region of the W axis (less than 1 μm in length and having a terminal recombination nodule). Competition for pairing between the gonosomes results in a large (93.5% of cases) predominance of Z–Z pairing, because of a relatively minor homology between the W and Z chromosomes. The prevailing pairing failure of the W chromosome may lead to early oocyte loss.Key words: sex chromosomes, triploids, synaptonemal complex, Z–W pairing, chicken, recombination nodules.

Synaptonemal complex spreading in Allium cepa and Allium fistulosum. II. Pachytene observations: the SC karyotype and the correspondence of late recombination nodules and chiasmata

Genome ◽  
1988 ◽  
Vol 30 (3) ◽  
pp. 399-410 ◽  
Author(s):  
S. M. Albini ◽  
G. H. Jones
Keyword(s):  
Synaptonemal Complex ◽  
Allium Cepa ◽  
Positional Distribution ◽  
Allium Fistulosum ◽  
Dna Amount ◽  
Closely Related Species ◽  
Synaptonemal Complexes ◽  
Recombination Nodules ◽  
Surface Spreading ◽  
Metaphase I

Pachytene synaptonemal complexes and recombination nodules were analysed, by surface spreading, in the closely related species Allium fistulosum and Allium cepa (both 2n = 16), which show highly contrasting patterns of chiasma distribution. Pachytene observations show that all eight pairs of homologues are fully paired in both species, despite the pronounced localisation of chiasmata in A. fistulosum. Synaptonemal complex karyotype analysis reveals similar marker complexes in both species. These are presumed homoeologues, which, possibly due to the uneven distribution of the higher DNA amount found in A. cepa, rank in slightly different positions in the two karyotypes. Darkly staining ellipsoidal late recombination nodules were observed associated with PTA stained pachytene synaptonemal complexes. The positional distribution of late recombination nodules along synaptonemal complexes corresponds almost exactly to the distribution of chiasmata along metaphase I bivalents in the two species. These observations strongly support the proposal that late recombination nodules are involved in reciprocal meiotic recombination. The frequencies of late recombination nodules at pachytene showed deficits (30% in A. fistulosum, 70% in A. cepa) compared to metaphase I chiasma frequencies. It is suggested that the greater deficit of late recombination nodules in A. fistulosum could be related to a longer duration of meiosis in this species resulting from its greater genomic DNA content.Key words: synaptonemal complex, recombination nodules, Allium.

Synaptic defects of asynaptic homozygotes in maize at the electron microscope level

Genome ◽  
1996 ◽  
Vol 39 (6) ◽  
pp. 1194-1198 ◽  
Author(s):  
M. P. Maguire ◽  
R. W. Riess
Keyword(s):  
Electron Microscope ◽  
Key Words ◽  
Synaptonemal Complex ◽  
Central Region ◽  
Silver Staining ◽  
Central Element ◽  
Electron Microscope Level ◽  
Recombination Nodules ◽  
Element Type ◽  
Maize Plants

More detailed observations of the synaptonemal complex (SC) in asynaptic maize plants have been faciliated by superior silver-staining procedures. These suggest that central region components of the SC are strongly implicated as defective in asynaptic. Apparently homologous axial elements tend to follow roughly parallel courses within the nucleus at pachytene, in some short segments apparently synapsed and in others at wider separation than normal synapsis yet close enough to allow observation of thin central element segments and also occasional thin transverse element-type structures. This kind of transverse filament may be weakened and severely stretched yet associated with both axial elements. Small nodules, similar to recombination nodules, appear at corresponding positions in widely separated axial elements. Key words : synaptonemal complex, central element, transverse filament, recombination nodule.

Electron-Microscopic localization of biotinylated gastrin bound to eosinophils in the rat stomach

1994 ◽  
Vol 52 ◽  
pp. 300-301
Author(s):  
Caroline A. Miller ◽  
David H. Nichols ◽  
Richard F. Murphy
Keyword(s):  
Electron Microscope ◽  
Phosphate Buffer ◽  
Uranyl Acetate ◽  
List Type ◽  
Cerium Chloride ◽  
Rat Stomach ◽  
Electron Microscopic ◽  
Human Sequence ◽  
Acetate Lead ◽  
Microscope Slides

Gastrin is a small peptide capable of both stimulating gastric acid secretion and acting as an enteric growth factor. Known functions of eosinophils in the rat stomach are related to immunological defense. Here we demonstrate the binding of biotinylated gastrin to rat stomach eosinophils in the electron microscope. Small pieces of stomach were fixed by immersion in 4% paraformaldehyde/0.1% glutaraldehyde in 0.1 M phosphate buffer, pH 7.4 for 1 hour. The tissue was then cryoprotected in 30% sucrose/0.1 M phosphate buffer, transferred to Tissue Tek OCT compound and frozen in isopentane cooled with liquid nitrogen. Transverse cryostat sections were cut at 25 μm, thawed in PBS and free floating sections exposed to 10−5 M biotinylated 1-17 gastrin (human sequence; Peninsula Labs) for 1 hour. Controls omitted the biotinylated gastrin from this step. Sections were then rinsed 3X in PBS and exposed to either:1).a 1:50 dilution of 10 nm Extravidin colloidal gold (Sigma) for 2 hours, or2).an avidin-biotin-alkaline phosphatase complex (ABC-AP;Vector) for 1 hour. A substrate solution containing cerium chloride was used to generate an electron dense reaction product.Sections from both procedures were postfixed in 1% OsO4 in 0.1 M phosphate buffer, rinsed and dehydrated. These were then flat embedded in EMbed 812 between two microscope slides coated with Liquid Release (both from Electron Microscopy Sciences).Polymerized sections were adhered to resin blocks using super glue, cut at 70-90 nm, stained with uranyl acetate/lead citrate and observed in a Philips CM-10 electron microscope.

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