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Prague, Czech Republic

Fulka H.,Institute of Animal Science | Langerova A.,Gennet
Development (Cambridge)

The oocyte (maternal) nucleolus is essential for early embryonic development and embryos originating from enucleolated oocytes arrest at the 2-cell stage. The reason for this is unclear. Surprisingly, RNA polymerase I activity in nucleolus-less mouse embryos, as manifested by pre-rRNA synthesis, and pre-rRNA processing are not affected, indicating an unusual role of the nucleolus. We report here that the maternal nucleolus is indispensable for the regulation of major and minor satellite repeats soon after fertilisation. During the first embryonic cell cycle, absence of the nucleolus causes a significant reduction in major and minor satellite DNA by 12% and 18%, respectively. The expression of satellite transcripts is also affected, being reduced by more than half. Moreover, extensive chromosome bridging of the major and minor satellite sequences was observed during the first mitosis. Finally, we show that the absence of the maternal nucleolus alters S-phase dynamics and causes abnormal deposition of the H3.3 histone chaperone DAXX in pronuclei of nucleolus-less zygotes. © 2014. Published by The Company of Biologists Ltd. Source

Fulka H.,Institute of Animal Science | Martinkova S.,Institute of Animal Science | Kyogoku H.,Kobe University | Langerova A.,Gennet | Fulka Jr. J.,Institute of Animal Science
Journal of Reproduction and Development

Compared with advanced developmental stage embryos and somatic cells, fully grown mammalian oocytes contain specific nucleolus-like structures (NPB - nucleolus precursor bodies). It is commonly accepted that they serve as a store of material(s) from which typical nucleoli are gradually formed. Whilst nucleoli from somatic cells can be collected relatively easily for further biochemical analyses, a sufficient number of oocyte nucleoli is very difficult to obtain. We have found that isolated oocytes nucleoli fuse very efficiently when contact is established between them. Thus, well visible giant nucleoli can be obtained, relatively easily handled and then used for further biochemical analyses. With the use of colloidal gold staining, we estimated that a single fully grown mouse oocyte nucleolus contains approximately 1.6 ng of protein. We do believe that this approach will accelerate further research aiming at analyzing the composition of oocyte nucleoli in more detail. © 2012 by the Society for Reproduction and Development. Source

Kousal B.,Charles University | Zahlava J.,R.O.S.A. | Vejvalkova S.,Ustav Biologie a Lekarske Genetiky | Hejtmankova M.,Gennet | Liskova P.,Charles University
Ceska a Slovenska Oftalmologie

Purpose: The aim of our study was to describe the phenotype and to perform molecular genetic investigation in two probands of Czech origin diagnosed with Stargardt disease (STGD). Methods: Both males underwent ocular examination including assessment by high-resolution spectral domain optical coherence tomography (SD-OCT). DNA was isolated from venous blood. Mutation detection was performed using the ABCA4 genotyping microarray (Asper Ophthalmics, Estonia). Results: The best corrected visual acuity in proband 1 (aged 39 years) was 0.1 bilaterally, and 0.05 in proband 2 (aged 26 years). Fundus examination showed typical multiple yellow-white lesions and macular atrophy. Alterations of retinal pigment epithelium, retinal thinning and disruption of the photoreceptor inner segment ellipsoid band were detected with an SD-OCT. Two known disease-causing mutations in ABCA4 were identified in proband 1; c.4234C>T, p.(Gln1412∗) in exon 28; and c.5882G>A, p.(Gly1961Glu) in exon 42. Only one pathogenic change was detected in proband 2; c.1988G>A, p.(Trp663∗) in exon 14. A second change, anticipated because of the recessive status of the disease, was not identified. Conclusion: The frequency and full spectrum of ABCA4 mutations in Czech patients with inherited retinal disorders is yet to be established. The inability to detect a second pathogenic change in ABCA4 coding sequences in proband 2 warrants further investigation. Source

Background: The overall incidence of childhood malignancies is rather low. Central nervous system tumours constitute the largest group of solid tumours among children. In contrast to adult population, a genetic predisposition is frequently associated with these malignancies (it is assumed to occur in approximately 15-25% of all childhood tumours) and there is also a number of monogenic hereditary syndromes known to be associated with brain tumours. Aim: The purpose of this article is to present an overview of genetic syndromes reported to increase the risk of childhood central nervous system tumours. The outlined tumour predispositions are divided into two groups. Firstly, syndromes with multisystem manifestation, where neoplasia is one of the components, whereas the distinguishing symptom is usually non-oncological. Secondly, there are syndromes that are diagnosed by the associated neoplasm withou any other noticeable phenotypic manifestation. A brief description of particular diseases is provided with a focus on associated central nervous system tumours. Detection of a tumour predisposition in a child is important not only for the child itself, but also for its family relatives. Often, a modification of treatment is necessary in regards to a genetic diagnosis. With the evolution of personalised medicine the possibility of "tailored" therapy will probably be a demanded solution. Last but not least, it is crucial to provide the child with a specialised preventive care owing to the risk of another potential malignancy. The diagnosis of hereditary cancer predisposition has also a big impact on the relatives of the patient. It enables to specify their oncological risk and arrange a specialised preventive care program, if needed. For high-risk parents planning another pregnancy there is a possibility to prevent the transfer of a certain disposition with the aid of preimplantation and prenatal genetic testing. Source

Hancarova M.,Charles University | Vejvalkova S.,Charles University | Trkova M.,Gennet | Drabova J.,Charles University | And 3 more authors.

Microdeletions spanning 2p14-p15 have recently been described in two patients with developmental and speech delay and intellectual disability but no congenital malformations or severe facial dysmorphism. We report a 4-year-old boy with a de novo 3.7. Mb long deletion encompassing the region deleted in the previous cases. The patient had clinical features partly consistent with the published cases including intellectual disability, absent speech, microcephaly, long face, bulbous nasal tip and thin upper lip, but his overall clinical picture was more severe compared to the published patients. The identification of this additional patient and a detailed analysis of deletions identified in various patient cohorts and in normal individuals support the existence of a new rare microdeletion syndrome in 2p14-p15. Its critical region is in the vicinity of but clearly separate from the minimal region deleted in the well established 2p15-p16.1 microdeletion syndrome. A thorough comparison of the deletions and phenotypes indicates that multiple genes located in this region may be involved in intellectual functioning, and that some patients may show composite and more complex phenotypes due to deletions spanning both critical regions. © 2012 Elsevier B.V. Source

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