Publications by authors named "Kurg A"

Article Synopsis
  • This study focuses on embryonic genome activation (EGA) in bovine embryonic development, highlighting the need to understand the role of PRD-like (PRDL) transcription factors that are crucial for this process but have evolved differently across species.
  • Molecular cloning was performed on several PRDL TFs in bovine oocytes and IVF preimplantation embryos, confirming their expression and revealing breed-related genetic variations through the identification of numerous single nucleotide variants (SNVs).
  • The research demonstrated that overexpressing the TPRX3 gene in bovine fibroblasts activates not only protein-coding genes but also small noncoding RNAs, supporting the notion of shared gene sets in early bovine
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Article Synopsis
  • Pregnancy loss is frequently linked to chromosomal abnormalities, with a study revealing that about 50.4% of spontaneous losses had karyotypically abnormal products of conception, influenced by parental age.
  • The researchers examined 94 cases of loss with normal karyotypes and discovered that 35.1% exhibited previously undetected chromosomal issues, raising the overall rate of abnormalities to 67.8%.
  • Findings indicate that unlike viable pregnancies, where abnormalities are often limited to chorionic villi, pregnancy losses show more mosaicism in extra-embryonic tissues, highlighting the need for deeper analysis of genomic abnormalities to enhance understanding and treatment.
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Human granulosa cells acquired as leftover from IVF treatment can be used to study infertility problems and are a valuable tool in the research of follicle maturation and ovulation. There is a need for more defined and long-term culture protocols for studying the response of granulosa cells upon treatment with selected hormones/chemicals. In the current study, we tested the effect of adding FGF2, IGF2 and FSH into defined basal medium in order to find culture conditions that would support proliferation of cumulus and mural granulosa cells along with the expression of common granulosa cell type markers such as FSHR, AMHR2, LHR and CYP19A1.

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MicroRNAs (miRNAs) are known post-transcriptional regulators of various biological processes including ovarian follicle development. We have previously identified miRNAs from human pre-ovulatory ovarian granulosa cells that are expressed from the intronic regions of two key genes in normal follicular development: FSH receptor (FSHR) and CYP19A1, the latter encoding the aromatase enzyme. The present study aims to identify the target genes regulated by these miRNAs: hsa-miR-548ba and hsa-miR-7973, respectively.

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Chromatin immunoprecipitation coupled with next-generation sequencing (ChIP-seq) has revolutionized our understanding of chromatin-related biological processes. The method, however, requires thousands of cells and has therefore limited applications in situations where cell numbers are limited. Here we describe a novel method called Restriction Assisted Tagmentation Chromatin Immunoprecipitation (RAT-ChIP) that enables global histone modification profiling from as few as 100 cells.

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Objective: The study aimed to validate a whole-genome sequencing-based NIPT laboratory method and our recently developed NIPTmer aneuploidy detection software with the potential to integrate the pipeline into prenatal clinical care in Estonia.

Method: In total, 424 maternal blood samples were included. Analysis pipeline involved cell-free DNA extraction, library preparation and massively parallel sequencing on Illumina platform.

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Although chromosomal instability (CIN) is a common phenomenon in cleavage-stage embryogenesis following in vitro fertilization (IVF), its rate in naturally conceived human embryos is unknown. CIN leads to mosaic embryos that contain a combination of genetically normal and abnormal cells, and is significantly higher in in vitro-produced preimplantation embryos as compared to in vivo-conceived preimplantation embryos. Even though embryos with CIN-derived complex aneuploidies may arrest between the cleavage and blastocyst stages of embryogenesis, a high number of embryos containing abnormal cells can pass this strong selection barrier.

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Background: Usage of sexed semen that allows to choose the gender of the calves, is commonly practiced in livestock industry as a profitable breeding alternative, especially in dairy farming. The flow cytometric cell sorting is the only commercially available method for bovine sperm sexing. For validation of the sexing procedure several methods have been developed including sperm fluorescence in situ hybridisation techniques.

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Objective: To compare the genomic profiles of blastocoel fluid (BF), inner cell mass (ICM), and trophectoderm (TE) cells derived from the same blastocyst.

Design: Prospective study.

Setting: Academic and in vitro fertilization units.

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Non-invasive prenatal testing (NIPT) is a recent and rapidly evolving method for detecting genetic lesions, such as aneuploidies, of a fetus. However, there is a need for faster and cheaper laboratory and analysis methods to make NIPT more widely accessible. We have developed a novel software package for detection of fetal aneuploidies from next-generation low-coverage whole genome sequencing data.

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The journey of embryonic development starts at oocyte fertilization, which triggers a complex cascade of events and cellular pathways that guide early embryogenesis. Recent technological advances have greatly expanded our knowledge of cleavage-stage embryo development, which is characterized by an increased rate of whole-chromosome losses and gains, mixoploidy, and atypical cleavage morphokinetics. Embryonic aneuploidy significantly contributes to implantation failure, spontaneous miscarriage, stillbirth or congenital birth defects in both natural and assisted human reproduction.

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Study Question: Is the rate and nature of chromosome instability (CIN) similar between bovine in vivo-derived and in vitro-cultured cleavage-stage embryos?

Summary Answer: There is a major difference regarding chromosome stability of in vivo-derived and in vitro-cultured embryos, as CIN is significantly lower in in vivo-derived cleavage-stage embryos compared to in vitro-cultured embryos.

What Is Known Already: CIN is common during in vitro embryogenesis and is associated with early embryonic loss in humans, but the stability of in vivo-conceived cleavage-stage embryos remains largely unknown.

Study Design, Size, Duration: Because human in vivo preimplantation embryos are not accessible, bovine (Bos taurus) embryos were used to study CIN in vivo.

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Study Question: Can spontaneous premature ovarian failure (POF) patients derived from population-based biobanks reveal the association between copy number variations (CNVs) and POF?

Summary Answer: CNVs can hamper the functional capacity of ovaries by disrupting key genes and pathways essential for proper ovarian function.

What Is Known Already: POF is defined as the cessation of ovarian function before the age of 40 years. POF is a major reason for female infertility, although its cause remains largely unknown.

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Dramatic genome dynamics, such as chromosome instability, contribute to the remarkable genomic heterogeneity among the blastomeres comprising a single embryo during human preimplantation development. This heterogeneity, when compatible with life, manifests as constitutional mosaicism, chimerism, and mixoploidy in live-born individuals. Chimerism and mixoploidy are defined by the presence of cell lineages with different parental genomes or different ploidy states in a single individual, respectively.

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Background: Somatic mosaicism denotes the presence of genetically distinct populations of somatic cells in one individual who has developed from a single fertilised oocyte. Mosaicism may result from a mutation that occurs during postzygotic development and is propagated to only a subset of the adult cells. Our aim was to investigate both somatic mosaicism for copy-neutral loss of heterozygosity (cn-LOH) events and DNA copy number variations (CNVs) in fully differentiated tissues.

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Study Question: What is the measured prevalence and phenotype of spontaneous premature ovarian failure (POF) in the general population?

Summary Answer: Spontaneous POF occurs in ∼1% of the general population with unique phenotype of post-menopausal ageing distinct from surgically induced premature menopause.

What Is Known Already: POF is multifactorial ovarian quiescence before the age of 40. The clinical features of POF are diverse and the population prevalence of POF is still not known.

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The causative variant in a consanguineous family in which the three patients (two siblings and a cousin) presented with intellectual disability, Marfanoid habitus, craniofacial dysmorphisms, chronic diarrhea and progressive kyphoscoliosis, has been identified through whole exome sequencing (WES) analysis. WES study identified a homozygous DDC variant in the patients, c.1123C>T, resulting in p.

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Chromosome 17q21.31 microdeletion syndrome is a genomic disorder caused by a recurrent 600 kb long deletion. The deletion affects the region of a common inversion present in about 20% of Europeans.

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There is a growing need for quick and reliable methods for microorganism detection and identification worldwide. Although traditional culture-based technologies are trustworthy and accurate at a relatively low cost, they are also time- and labor-consuming and are limited to culturable bacteria. Those weaknesses have created a necessity for alternative technologies that are capable for faster and more precise bacterial identification from medical, food or environmental samples.

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Chromosomal microarray analysis (CMA) is now established as the first-tier cytogenetic diagnostic test for fast and accurate detection of chromosomal abnormalities in patients with developmental delay/intellectual disability (DD/ID), multiple congenital anomalies (MCA), and autism spectrum disorders (ASD). We present our experience with using CMA for postnatal and prenatal diagnosis in Estonian patients during 2009-2012. Since 2011, CMA is on the official service list of the Estonian Health Insurance Fund and is performed as the first-tier cytogenetic test for patients with DD/ID, MCA or ASD.

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Article Synopsis
  • EXCAVATOR is a new software tool designed to detect copy number variants (CNVs) from whole-exome sequencing data using a unique algorithm and normalization method.
  • The tool categorizes genomic regions into five different copy number states and was validated against three datasets, where it showed superior performance compared to three other CNV detection methods.
  • EXCAVATOR is available for free download and can be useful for large-scale genetic research projects as well as clinical diagnostics, enhancing the analysis of genomic variations.
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The human WBSCR22 protein was previously shown to be up-regulated in invasive breast cancer and its ectopic expression enhances tumor cell survival in the vasculature. In the current study, we show that the WBSCR22 protein is important for cell growth. Knock-down of WBSCR22 with siRNA results in slower growth of WBSCR22-depleted cells.

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The 2p15-p16.1 microdeletion syndrome is a novel, rare disorder characterized by developmental delay, intellectual disability, microcephaly, growth retardation, facial abnormalities, and other medical problems. We report here on an 11-year-old female showing clinical features consistent with the syndrome and carrying a de novo 0.

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The recent implementation of array techniques in research and clinical practice has revealed the existence of recurrent reciprocal deletions and duplications in several genome loci. The most intriguing feature is that some reciprocal genomic events can result in opposite phenotypic outcome. One of such examples is 5q35.

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We report on a de novo 17q21.33 microdeletion, 1.8 Mb in size, detected in a patient with mild intellectual disability, growth retardation, poor weight gain, microcephaly, long face, large beaked nose, thick lower lip, micrognathia and other dysmorphic features.

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