scholarly journals Chromosome 18 pairing behavior in human trisomic oocytes. Presence of an extra chromosome extends bouquet stage

Reproduction ◽  
2005 ◽  
Vol 129 (5) ◽  
pp. 565-575 ◽  
Author(s):  
I Roig ◽  
P Robles ◽  
R Garcia ◽  
I Martínez-Flores ◽  
Ll Cabero ◽  
...  

Little is known about the first meiotic prophase stages in the human female because these occur during fetal life, and only a few studies have addressed aneuploid human oocytes. In this paper, the synaptic process in the meiotic prophase in three 47, XX + 18 cases is analyzed. A complete study of the dynamics of centromeres and telomeres, cohesin core and synapsis development in aneuploid female meiosis was performed. Investigation of chromosome dynamics in prophase of trisomy 18 oocytes show that these events follow the major patterns seen earlier in euploid oocytes. However, there is a significant delay in the resolution of bouquet topology which could relate to the presence of a surplus chromosome 18 axial element in zygotene oocytes. Pachytene oocytes displayed normal synapsis among the three chromosome 18s. However, in some oocytes the surplus chromosome 18 core was aligned to the bivalent 18. As ataxia telangiectasia and Rad3 related kinase (ATR) has been described as a marker for late-pairing chromosomes in mice, ATR distribution was analyzed in human meiocytes –spermatocytes, euploid oocytes and trisomic oocytes. In contrast to the observations made in mice, no preferential staining for late-pairing chromosomes was observed in humans. In the cases studied, bivalent synapses progressed as in a normal ovary, contrasting with the hypothesis that a surplus chromosome can modify pairing of other chromosomes.


2003 ◽  
Vol 160 (5) ◽  
pp. 657-670 ◽  
Author(s):  
Maureen Eijpe ◽  
Hildo Offenberg ◽  
Rolf Jessberger ◽  
Ekaterina Revenkova ◽  
Christa Heyting

In meiotic prophase, the sister chromatids of each chromosome develop a common axial element (AE) that is integrated into the synaptonemal complex (SC). We analyzed the incorporation of sister chromatid cohesion proteins (cohesins) and other AE components into AEs. Meiotic cohesin REC8 appeared shortly before premeiotic S phase in the nucleus and formed AE-like structures (REC8-AEs) from premeiotic S phase on. Subsequently, meiotic cohesin SMC1β, cohesin SMC3, and AE proteins SCP2 and SCP3 formed dots along REC8-AEs, which extended and fused until they lined REC8-AEs along their length. In metaphase I, SMC1β, SMC3, SCP2, and SCP3 disappeared from the chromosome arms and accumulated around the centromeres, where they stayed until anaphase II. In striking contrast, REC8 persisted along the chromosome arms until anaphase I and near the centromeres until anaphase II. We propose that REC8 provides a basis for AE formation and that the first steps in AE assembly do not require SMC1β, SMC3, SCP2, and SCP3. Furthermore, SMC1β, SMC3, SCP2, and SCP3 cannot provide arm cohesion during metaphase I. We propose that REC8 then provides cohesion. RAD51 and/or DMC1 coimmunoprecipitates with REC8, suggesting that REC8 may also provide a basis for assembly of recombination complexes.



PMLA ◽  
1953 ◽  
Vol 68 (1) ◽  
pp. 170-188
Author(s):  
Karl J. R. Arndt

After Otto Heller published the results of his investigations into the question of Charles Sealsfield's claimed editorship of the Courrier des Etats-Unis in the Euphorion in 1907 (xiv, 718-724), he was convinced that he had disproved “the biographical fable that makes Sealsfield editor of the Courrier des États-Unis.” This assertion was repeated in 1939 in the important Heller-Leon Sealsfield Bibliography and more recently in an article published by the Zeitschrift für deutsche Philologie, to which Professor Eduard Castle of the University of Vienna then made an enlightening but inconclusive reply because he did not have access to copies of the Courrier. In view of the fact that to date Otto Heller's study remains the only one based on an actual examination of the Courrier itself, the weight of evidence must remain in favor of his published conclusions unless these are disproved by more valid evidence from the same source. On the basis of a more complete study of the record it is believed that the following pages will bring such evidence and thus reestablish and confirm Sealsfield's original claim made in his biographical letter to Brockhaus asserting that from 1829-30 he was editor of the Courrier and that he resigned several weeks after news of the French Revolution of 1830 reached America. This will not only correct an unfortunate error in Sealsfield scholarship, but also clear Sealsfield against a charge of untruthfulness.



Reproduction ◽  
2007 ◽  
Vol 133 (5) ◽  
pp. 899-907 ◽  
Author(s):  
P Robles ◽  
I Roig ◽  
R Garcia ◽  
A Ortega ◽  
J Egozcue ◽  
...  

Only little is known about the meiotic prophase events in human oocytes, although some of them are involved in the origin of aneuploidies. Here, a broad study of the pairing and synaptic processes in 3263 human euploid and 2613 aneuploid oocytes (47,XX, +21 and 47,XX, +13), using different techniques and methods, is presented in order to elucidate the characteristics of this essential meiotic process. Our results reaffirm the existence of a common high efficiency in the pairing process leading to the obtainment of a bivalent for all chromosomes studied in euploid and aneuploid cases. Nevertheless, this high efficiency was insufficient to consistently produce trivalents in aneuploid oocytes. Trivalent 21 was only observed in 48.8% of the 47,XX, +21 pachytene-stage oocytes studied, and trivalent 13 was found in 68.7% of the 47,XX, +13 pachytene-stage oocytes analyzed. Our data confirm the hypothesis which suggests that in human oocytes the presence of an extra chromosome could interfere in bouquet dynamics. In addition, the pairing process of the X chromosome is altered in trisomic 21 oocytes, providing evidence of the influence that an extra chromosome 21 may cause meiotic progression.



In the first part of this paper I described the life-history, spermatogenesis, maturation of the fertilised egg, fertilisation and segmentation divisions of the summer generation of the gall-fly Neuroterus lenticularis ( Spathegaster baccarum ), and gave some observations on the maturation of the eggs of the spring generation, and on the somatic mitoses in males and females. These latter observations were admittedly incomplete owing to lack of material, and this second part of the paper attempts to complete the account of what was left uncertain in the first communication. Before proceeding to describe my fresh observations it may be well shortly to summarise the results arrived at in the fist part. The spring generation of N. lenticularis consists of females which lay parthenogenetic eggs; those laid by some females develop into sexual females, both of which hatch in June. The eggs of the summer females undergo a double maturation division, leaving 10 chromosomes in the nucleus of the mature egg. The spermatogonia of the males in the same generation have 10 chromosomes; the first spermatocyte division is suppressed; in the second spermatocyte division the chromosomes divide, 10 entering each spermatid. A small staining extra-nuclear body found in the spermatocytes does not divide, and is included in only half of the spermatids. In fertilisation, the egg and sperm nuclei each contain 10 chromosomes, and the segmentation divisions of the fertilised egg show 20. For a complete study of the maturation and segmentation of the parthenogenetic spring eggs my material was insufficient, but it suggested that the eggs laid by some females underwent maturation and showed 10 chromosomes in the segmentation divisions, and that others had no polar divisions and showed 20. Since somatic and oogonial mitoses of the summer female have 20 chromosomes, but the spermatogonial mitoses and those of the developing nervous system in the male only 10, it was suggested that the eggs which undergo maturation produce males, the others females. An attempt was made, in conclusion, to connect these phenomena with what is know of sex-determination in other animals.



Ars Adriatica ◽  
2012 ◽  
pp. 177
Author(s):  
Igor Fisković

Three cinquecento polychrome wood-carved altars have been preserved on the island of Lopud near Dubrovnik, the most monumental of which is situated in the parish church of Our Lady of Šunj. Its retable was constructed to resemble a classical aedicule, with an intricately carved frame and a central figural depiction of the Assumption of the Virgin, complemented by a complex iconographic programme in the symmetrically arranged adjoining scenes. Filling the small cassettes of the predella are reliefs of the Annunciation and Christ as the Man of Sorrows, together with perspectively rendered narrative scenes of the Last Supper and the Washing of the Feet, while in the pediment is a frontal depiction of the Coronation of the Virgin by the Holy Trinity. In the narrow side wings between the columns and pilasters are four bas-reliefs of local patron saints depicted half-turned towards the central image, and thus achieving an overall plastic harmony for a demanding content. In terms of space, the main scene is well-developed through a pronounced sculptural modelling of the figures of the eleven apostles in the round, the most prominent of which is that of St Peter, placed in the foreground and turned to face the nave of the church, while the others are consumed by the miraculous assumption of the Virgin into heaven. She is followed high up by a pair of small angels and several tiny symbolical cherubim heads, all of which helps to achieve an extremely convincing religious scene. Its attractiveness is significantly heightened by the all’antica realism and pedantic Roman-inspired modelling which highlight the skill of a highly trained and talented master wood carver, which leaves no doubt that this is a special work of art, and indeed, the most beautiful carved wood retable in the east Adriatic which has survived to date. In this first complete study of the altar, the author traces historical records in which it is mentioned without the exact year of its creation, origin or carver being cited. He dispels the tradition that the altar was brought from England, supposedly from the Chapel of Henry VIII, and explains this tradition as having been based on the discovery of an alabaster altar, a typical product of late Gothic workshops at Nottingham, several examples of which exist in Dalmatia. From the seventeenth-century records, on the other hand, we learn that the altar in the church of the „Madonna del Sugni” (a vernacular Italo-Croatian transformation of the word Assunta) was dedicated in 1572. An examination of comparative material establishes that the altar’s compositional scheme draws upon altarpieces painted by Alvise Vivarini around 1480, while its morphological features find their closest parallel in the activities and mannerisms of the Venetian workshop of Paolo Campsa, who worked from the 1490s to the early 1550s, and who sold his works in the wide area under the government of La Serenissima. The Republic of Venice profited a great deal from this export, while its urban centre’s innumerable wooden altars disappeared following subsequent changes of fashion. A group of securely attributed works shows that Paolo Campsa frequently borrowed formulas and idioms from Venetian painters of the older generation; analogies with two of Vivarini’s altar paintings confirm that he repeated this technique on the Lopud altar, even though altars as complex as this are not found in the surviving oeuvre of this artist. An overview of the extremely numerous works attributed to this fecund wood carver has not led to a secure attribution of this scenically developed altar to his hand. However, an analytical observation points to significant similarities with individual figures considered by scholars of Renaissance wooden sculpture to be products of his workshop - more a factory, in fact - or of his circle which, without a doubt, Paolo stamped with his mark. Apart from the assumption that there are master wood carvers who have not been identified, or formally and clearly differentiated, who followed his teachings and mannerisms, this paper opens the possibility of locating more exactly the place of the altar’s creation. Since Campsa’s workshop was active even after his death, it can be assumed that the altar was made in the 1560s or 1570s, and that it was transported and assembled on the island of Lopud for its dedication of 1572. Furthermore, the author observes the meaning of the subsequent addition of the background, which was painted once the altar reached its destination; it shows a summarized depiction of the scenery of Lopud and a tiny settlement with a precisely and proportionately drawn sailing ship docked at the island’s bay. The background reveals that the nature of the work was votive and, by identifying the layers of local historical circumstance and by combining them with the relevant written sources, it can be connected to the activities of the distinguished ship owner Miho Pracat, the richest citizen of the Republic of Dubrovnik during the cinquecento. Two more wooden sculptures can be added to Miho Pracat’s donation to his home island: the figures of St Catherine and St Roch which were also made in Venice and which had originally belonged to a small altar of his family in the local church of St Francis, known from archival records. This altar was composed of an older polychrome triptych, now unfortunately lost, and which, together with a pair of side statues, formed a piece resembling a number of altarpieces from Paolo Campsa’s workshop. Thus, the analysis of these works of art reveals key components of visual culture, and a peculiar mosaic of sixteenth-century artistic production in a peripheral community of the small island of Lopud under the government of the Republic of Dubrovnik.



2019 ◽  
Vol 02 (01) ◽  
pp. 069-073
Author(s):  
Rupa Ananthasivan ◽  
Sudarshan Rawat ◽  
Pramesh Reddy ◽  
Pooja G. Patil ◽  
Chittur Narendra Radhakrishnan

AbstractDuodenal stenosis is part of a spectrum of disorders due to non-cannulization of the fetal gut lumen occurring in 11 to 13 weeks of fetal life. The diagnosis is often made in the neonatal period owing to bilious vomiting. The authors present a case of a 9-year-old boy who was diagnosed by an upper gastrointestinal study that showed a hugely dilated stomach filled with food residue and a dilated first part of the duodenum with an abrupt narrowing in the second part of the duodenum in keeping with duodenal stenosis. There was no associated malrotation (a known association), but the delayed images showed a surprising finding of herniation of large bowel loops into the thorax suggestive of a congenital diaphragmatic hernia (Bochdalek type). Both these findings were confirmed on surgery, and the patient underwent duodenoduodenostomy and diaphragmatic hernia repair and is doing well on follow-up. This case is unusual due to the rare association of duodenal stenosis with congenital diaphragmatic hernia and delayed diagnosis. Both these pathologies most often present in the neonatal period, and delayed diagnosis is most often seen with associated trisomy 21 that was not the case in our patient.



1994 ◽  
Vol 127 (2) ◽  
pp. 273-285 ◽  
Author(s):  
H Scherthan ◽  
J Bähler ◽  
J Kohli

Interactions between homologous chromosomes (pairing, recombination) are of central importance for meiosis. We studied entire chromosomes and defined chromosomal subregions in synchronous meiotic cultures of Schizosaccharomyces pombe by fluorescence in situ hybridization. Probes of different complexity were applied to spread nuclei, to delineate whole chromosomes, to visualize repeated sequences of centromeres, telomeres, and ribosomal DNA, and to study unique sequences of different chromosomal regions. In diploid nuclei, homologous chromosomes share a joint territory even before entry into meiosis. The centromeres of all chromosomes are clustered in vegetative and meiotic prophase cells, whereas the telomeres cluster near the nucleolus early in meiosis and maintain this configuration throughout meiotic prophase. Telomeres and centromeres appear to play crucial roles for chromosome organization and pairing, both in vegetative cells and during meiosis. Homologous pairing of unique sequences shows regional differences and is most frequent near centromeres and telomeres. Multiple homologous interactions are formed independently of each other. Pairing increases during meiosis, but not all chromosomal regions become closely paired in every meiosis. There is no detectable axial compaction of chromosomes in meiotic prophase. S. pombe does not form mature synaptonemal complexes, but axial element-like structures (linear elements), which were analyzed in parallel. Their appearance coincides with pairing of interstitial chromosomal regions. Axial elements may define minimal structures required for efficient pairing and recombination of meiotic chromosomes.



Reproduction ◽  
2003 ◽  
pp. 589-597 ◽  
Author(s):  
PT Saunders ◽  
JM Turner ◽  
M Ruggiu ◽  
M Taggart ◽  
PS Burgoyne ◽  
...  

The autosomal gene DAZL is a member of a family of genes (DAZL, DAZ, BOULE), all of which contain a consensus RNA binding domain and are expressed in germ cells. Adult male and female mice null for Dazl lack gametes. In order to define more precisely the developmental stages in germ cells that require Dazl expression, the patterns of germ cell loss in immature male and female wild-type (+/+, WT) and Dazl -/- (DazlKO) mice were analysed. In females, loss of germ cells occurred during fetal life and was coincident with progression of cells through meiotic prophase. In males, testes were recovered from WT and DazlKO males obtained before and during the first wave of spermatogenesis (days 2-19). Mitotically active germ cells were present up to and including day 19. Functional differentiation of spermatogonia associated with detection of c-kit positive cells did not depend upon expression of Dazl. RBMY-positive cells (A, intermediate, B spermatogonia, zygotene and preleptotene spermatocytes) were reduced in DazlKO compared with WT testes. Staining of cell squashes from day 19 testes with anti-gamma-H2AX and anti-SCP3 antibodies showed that germ cells from DazlKO males were unable to progress beyond the leptotene stage of meiotic prophase I. It was concluded that in the absence of Dazl, germ cells can complete mitosis, and embark on functional differentiation but that, in both sexes, progression through meiotic prophase requires this RNA binding protein.



1969 ◽  
Vol 40 (2) ◽  
pp. 542-551 ◽  
Author(s):  
Peter B. Moens

At meiotic prophase, the grasshopper Chorthippus longicornis has normal synaptinemal complexes inside paired homologous chromosomes. Evidence is presented that short single cores and small multiple core complexes occur inside metaphase I chromosomes. At first anaphase, interphase, and early spermatid stage, large multiple core complexes are located in the cytoplasm. It is speculated that the multiple core complexes have some structural elements in common with the synaptinemal complexes, but that different forms of pairing behavior are exhibited by the different complexes.



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