scholarly journals Pairing and synapsis in oocytes from female fetuses with euploid and aneuploid chromosome complements

Reproduction ◽  
2007 ◽  
Vol 133 (5) ◽  
pp. 899-907 ◽  
Author(s):  
P Robles ◽  
I Roig ◽  
R Garcia ◽  
A Ortega ◽  
J Egozcue ◽  
...  
Keyword(s):  
X Chromosome ◽  
Meiotic Prophase ◽  
High Efficiency ◽  
Extra Chromosome ◽  
Chromosome 21 ◽  
Pachytene Stage ◽  
Meiotic Process ◽  
Human Oocytes ◽  
Meiotic Progression ◽  
Aneuploid Chromosome

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.

Cytological aspects of gametogenesis in two rhigonematid (Nematoda) parasites of Anadenobolus politus (Porat) (Rhinocricidae; Diplopoda) from Guadeloupe

1984 ◽  
Vol 62 (2) ◽  
pp. 190-192 ◽  
Author(s):  
Martin L. Adamson ◽  
Daniel Van Waerebeke
Keyword(s):  
X Chromosome ◽  
Meiotic Prophase ◽  
Meiotic Metaphase ◽  
Autosomal Pair

Certain cytological aspects of gametogenesis are examined in two species of rhigonematid nematodes parasitizing the posterior gut of Anadenobolus politus (Rhinocricidae; Diplopoda) in Guadeloupe. In both species, sex is determined by an XX/XO mechanism; this is taken as an indication of the phylogenetic distinctness of rhigonematids from the order Oxyurida which recent studies show to be haplodiploid. In Ichthyocephalus anadenoboli. males had 9 and females had 10 chromosomes; in Heth mauriesi, males had 15 and females had 16 chromosomes. In both species, the X chromosome and one autosomal pair were positively heteropyenotic (i.e., they condensed before and stained more intensely than the rest of the chromosomes) during meiotic prophase in males; in H. mauriesi, these chromosomes were negatively heteropyenotic during meiotic metaphase in males. In females of both species, all chromosomes stained similarly.

The testis-specific transcript (ferT) of the tyrosine kinase FER is expressed during spermatogenesis in a stage-specific manner

1990 ◽  
Vol 10 (9) ◽  
pp. 5021-5025
Author(s):  
E Keshet ◽  
A Itin ◽  
K Fischman ◽  
U Nir
Keyword(s):  
In Situ Hybridization ◽  
Tyrosine Kinase ◽  
Tyrosine Kinases ◽  
Meiotic Prophase ◽  
Hybridization Analysis ◽  
Pachytene Stage ◽  
Specific Transcript ◽  
Specific Manner

ferT is a testis-specific transcript of FER encoding a truncated version of the potential tyrosine kinase. Using in situ hybridization analysis, we found that ferT was transiently expressed during spermatogenesis and that expression was restricted to spermatocytes at the pachytene stage of meiotic prophase. This pattern of expression is unprecedented by other tyrosine kinases and suggests a role for ferT in a particular stage of spermatogenesis.

Ts65Dn, a Mouse Model of Down Syndrome, Exhibits Increased GABAB-Induced Potassium Current

2007 ◽  
Vol 97 (1) ◽  
pp. 892-900 ◽  
Author(s):  
Tyler K. Best ◽  
Richard J. Siarey ◽  
Zygmunt Galdzicki
Keyword(s):  
Down Syndrome ◽  
Mouse Model ◽  
Hippocampal Neurons ◽  
Single Channel ◽  
Extra Chromosome ◽  
Functional Expression ◽  
Chromosome 21 ◽  
Fluctuation Analysis ◽  
Response Curves ◽  
Girk Channel

Down syndrome (DS) is the most common nonheritable cause of mental retardation. DS is the result of the presence of an extra chromosome 21 and its phenotype may be a consequence of overexpressed genes from that chromosome. One such gene is Kcnj6/Girk2, which encodes the G-protein-coupled inward rectifying potassium channel subunit 2 (GIRK2). We have recently shown that the DS mouse model, Ts65Dn, overexpresses GIRK2 throughout the brain and in particular the hippocampus. Here we report that this overexpression leads to a significant increase (∼2-fold) in GABAB-mediated GIRK current in primary cultured hippocampal neurons. The dose response curves for peak and steady-state GIRK current density is significantly shifted left toward lower concentrations of baclofen in Ts65Dn neurons compared with diploid controls, consistent with increased functional expression of GIRK channels. Stationary fluctuation analysis of baclofen-induced GIRK current from Ts65Dn neurons indicated no significant change in single-channel conductance compared with diploid. However, significant increases in GIRK channel density was found in Ts65Dn neurons. In normalized baclofen-induced GIRK current and GIRK current kinetics no difference was found between diploid and Ts65Dn neurons, which suggests unimpaired mechanisms of interaction between GIRK channel and GABAB receptor. These results indicate that increased expression of GIRK2 containing channels have functional consequences that likely affect the balance between excitatory and inhibitory neuronal transmission.

scholarly journals Ten Reasons Why People With Down Syndrome are Protected From the Development of Most Solid Tumors -A Review

2021 ◽  
Vol 12 ◽  
Author(s):  
Marta Pilar Osuna-Marco ◽  
Mónica López-Barahona ◽  
Blanca López-Ibor ◽  
Águeda Mercedes Tejera
Keyword(s):  
Down Syndrome ◽  
Solid Tumors ◽  
Tumor Suppressor Genes ◽  
Wilms Tumor ◽  
Extra Chromosome ◽  
Germ Cell Tumors ◽  
Chromosome 21 ◽  
Testicular Tumors ◽  
Unique Pattern ◽  
Increased Risk

People with Down syndrome have unique characteristics as a result of the presence of an extra chromosome 21. Regarding cancer, they present a unique pattern of tumors, which has not been fully explained to date. Globally, people with Down syndrome have a similar lifetime risk of developing cancer compared to the general population. However, they have a very increased risk of developing certain tumors (e.g., acute leukemia, germ cell tumors, testicular tumors and retinoblastoma) and, on the contrary, there are some other tumors which appear only exceptionally in this syndrome (e.g., breast cancer, prostate cancer, medulloblastoma, neuroblastoma and Wilms tumor). Various hypotheses have been developed to explain this situation. The genetic imbalance secondary to the presence of an extra chromosome 21 has molecular consequences at several levels, not only in chromosome 21 but also throughout the genome. In this review, we discuss the different proposed mechanisms that protect individuals with trisomy 21 from developing solid tumors: genetic dosage effect, tumor suppressor genes overexpression, disturbed metabolism, impaired neurogenesis and angiogenesis, increased apoptosis, immune system dysregulation, epigenetic aberrations and the effect of different microRNAs, among others. More research into the molecular pathways involved in this unique pattern of malignancies is still needed.

scholarly journals The asymmetry of female meiosis reduces the frequency of inheritance of unpaired chromosomes

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Daniel B Cortes ◽  
Karen L McNally ◽  
Paul E Mains ◽  
Francis J McNally
Keyword(s):  
Caenorhabditis Elegans ◽  
X Chromosome ◽  
High Frequency ◽  
Germ Line ◽  
Extra Chromosome ◽  
Polar Body ◽  
Contractile Ring ◽  
Female Meiosis ◽  
Random Segregation ◽  
The Asymmetry

Trisomy, the presence of a third copy of one chromosome, is deleterious and results in inviable or defective progeny if passed through the germ line. Random segregation of an extra chromosome is predicted to result in a high frequency of trisomic offspring from a trisomic parent. Caenorhabditis elegans with trisomy of the X chromosome, however, have far fewer trisomic offspring than expected. We found that the extra X chromosome was preferentially eliminated during anaphase I of female meiosis. We utilized a mutant with a specific defect in pairing of the X chromosome as a model to investigate the apparent bias against univalent inheritance. First, univalents lagged during anaphase I and their movement was biased toward the cortex and future polar body. Second, late-lagging univalents were frequently captured by the ingressing polar body contractile ring. The asymmetry of female meiosis can thus partially correct pre-existing trisomy.

scholarly journals Gambaran Erupsi Gigi Permanen pada Anak Sindrom Down Usia 10-16 Tahun di Sekolah Luar Biasa Kabupaten Jember

2018 ◽  
Vol 8 (1) ◽  
pp. 8
Author(s):  
Loly Anastasya Sinaga ◽  
Dwi Kartika Apriyono ◽  
Masniari Novita
Keyword(s):  
Down Syndrome ◽  
Special Needs ◽  
Physical Characteristic ◽  
Trisomy 21 ◽  
Genetic Disorder ◽  
Extra Chromosome ◽  
Descriptive Study ◽  
Chromosome 21 ◽  
Permanent Teeth ◽  
Intellectual Abilities

Background: Down Syndrome is a genetic disorder that occurs because of chromosome 21 has three chromosome (trisomy 21). The extra chromosome changes the genetic balance, physical characteristic, intellectual abilities, and physiological body function. Tooth eruption in Down Syndrome children typically delayed in both the timing and sequence of eruption up to two or three years. Objective: To observe the permanent teeth eruption in Down syndrome children at age 10-16 years old, boys and girls in Special Needs School in Jember. Materials and Methods: This research was a descriptive study with 7 subjects. Each subject was examined then calculated teeth that had emerged or functionally eruption with articualting paper. Result and Conclusion:  Both permanent teeth that is still partially erupted tooth (emerged/ EM) and had erupted perfectly (functionally eruption/ FE) delayed in eruption in Down Syndrome boys and girls at age 10-16 years old.

scholarly journals Predicting aneuploidy in human oocytes: key factors which affect the meiotic process

2010 ◽  
Vol 25 (9) ◽  
pp. 2374-2386 ◽  
Author(s):  
L. Gianaroli ◽  
M. C. Magli ◽  
G. Cavallini ◽  
A. Crippa ◽  
A. Capoti ◽  
...  
Keyword(s):  
Key Factors ◽  
Meiotic Process ◽  
Human Oocytes

Imbalances of Chromosome 21 in MDS/AML Include Cryptic Deletions but NOT RUNX1 Amplifications.

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 2561-2561
Author(s):  
Katya Gancheva ◽  
Diana Brazma ◽  
Nahid Zarein ◽  
Julie Howard-Reeves ◽  
Phaidra Partheniou ◽  
...  
Keyword(s):  
Down Syndrome ◽  
De Novo ◽  
Conflicts Of Interest ◽  
Lymphoblastic Leukemia ◽  
Extra Chromosome ◽  
Chromosome 21 ◽  
Oligonucleotide Array ◽  
Fish Analysis ◽  
Extra Copy ◽  
Commercial Fish

Abstract Abstract 2561 We present the results of a study demonstrating that the genome profile of RUNX1 in MDS/AML is characterised by hitherto unreported partial deletions and absence of amplifications. This is in stark contrast to reports of chromosome 21 amplifications in ALL. We speculate that the absence of RUNX1 deletions results from them being well below a size detectable by commercial FISH probes. Extra chromosome 21 is the second most common acquired trisomy after (+) 8 in adult myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). It is rarely observed as sole abnormality but seen as part of complex karyotype in some 3–7% of the AML (Atlas of Genetics and Cytogenetics in Oncology and Haematology, http://atlasgeneticsoncology.org). Although the gene(s) in trisomy 21 associated with leukemia are unknown, the 21q22 region appears to be critical since it houses the RUNX1 gene. Multiple amplified copies of the RUNX1 carried by marker chromosomes, such as iAML21, are described in both acute lymphoblastic leukemia (ALL) and AML. A common 5.1 Mb amplification containing the RUNX1, miR-802 and genes mapping to the Down syndrome critical region identified in 91 children with iAML21, was shown to be the likely initiating event in this rare form of childhood B-cell ALL (Rand et al., Blood, 2011). In contrast, recent studies of AML in a Down syndrome and a constitutionally normal individual showed lack of RUNX1, ETS2 and ERG involvement (Canzonetta et al., BJH, 2012). Here we present 16 MDS/AML cases with imbalances of chromosome 21 identified by genomic array screening from a cohort of 83 cases. Whole genome screening (aCGH) was performed on presentation samples of MDS /AML and de novo AML cases using an oligonucleotide array platform (Agilent) at 60K, 244K, 400K and 1M density. G banding and FISH analysis were also successfully performed. Gain of an extra copy (trisomy) of chromosome 21 (+21) was found in 9 patients, all but one with complex karyotypes. In 2 AMLs high level amplifications were detected at 21q22, which involved the ETS2 and ERG but not the RUNX1 sequences. While several commercially available RUNX1 FISH probes showed gene multiple signals, custom FISH probes covering the relevant regions confirmed that the amplifications excluded the RUNX1 but affected both EST2 and ERG thus rendering the commercial probes unfit to assess CNA in this genome area. In another two cases with trisomy 12, cryptic loss of 43Kb and 98Kb resp. within the RUNX1 sequences was detected and confirmed by FISH. Furthermore, similar deletions within the 21q22.12 were also found in another 7 cases all of which had diploid set of chromosome 21 but had multiple changes at G banding level and high TGA score. These RUNX1 deletions were variable in size, ranging from 98Kb to 2.7Mb. Although our observations excluded clinical correlations it is note worthy that most of the patients with RUNX1 loss have not achieved complete cytogenetic remission. These findings suggest role for the RUNX1 loss as indicator of progressive disease and provide a novel insight into pathogenesis of MDS/AML. Disclosures: No relevant conflicts of interest to declare.

Presence of an extra chromosome alters meiotic double-stranded break repair dynamics and MLH1 foci distribution in human oocytes

Chromosoma ◽  
2013 ◽  
Vol 122 (1-2) ◽  
pp. 93-102 ◽  
Author(s):  
P. Robles ◽  
I. Roig ◽  
R. Garcia ◽  
M. Brieño-Enríquez ◽  
M. Martin ◽  
...  
Keyword(s):  
Extra Chromosome ◽  
Human Oocytes ◽  
Break Repair ◽  
Mlh1 Foci
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