scholarly journals Human zygote reconstruction by spindle, polar body or pronuclear transfer to treat repeated embryo fragmentation or embryo developmental arrest: The future is now

2018 ◽  
pp. 049-051
Author(s):  
Economou KA
Keyword(s):  
Polar Body ◽  
Developmental Arrest ◽  
Embryo Fragmentation ◽  
The Future ◽  
Pronuclear Transfer

107 Insights from roe deer oocyte transcriptome across embryonic diapause

2019 ◽  
Vol 31 (1) ◽  
pp. 179
Author(s):  
S. M. Bernal-Ulloa ◽  
V. A. van der Weijden ◽  
J. T. Bick ◽  
A. B. Rüegg ◽  
B. Drews ◽  
...  
Keyword(s):  
Gene Ontology ◽  
False Discovery Rate ◽  
Roe Deer ◽  
Expression Profiles ◽  
Polar Body ◽  
Morphological Characteristics ◽  
Reduction Process ◽  
Immature Oocytes ◽  
Developmental Arrest ◽  
False Discovery

Embryonic developmental arrest, known as diapause, has been reported in more than 130 species. However, its mechanisms are still not completely understood. In the roe deer, the only known ungulate that exhibits this phenomenon, diapause lasts for approximately 5 months, starting after the rut period in mid-July to early August and ending with embryo elongation and implantation in December/January. Little is known regarding oocyte characteristics during this period. Here, we analysed the roe deer oocyte transcriptome as a model to understand diapause effects on oocyte features during embryonic developmental arrest and reactivation. During regular hunting, immature oocytes were obtained by ovary slicing from diapause and nondiapause stages, and classified according to morphological characteristics. Only oocytes with >2 layers of compact cumulus cells and cytoplasm from 30 hunted females were used for analyses. Immature oocytes were denuded and snap frozen. Additional oocytes were cultured in maturation medium for 20-24h. Matured oocytes with a present polar body were snap frozen. Two pools of 10 immature and mature oocytes for both diapause and nondiapause stages were included (at least 4 donors/pool). Oocyte pools were processed using the Smart-seq 2 single-cell protocol (Illumina Inc., San Diego, CA, USA) for full-length cDNA and library preparation. We performed RNA-seq on an Illumina sequencer. The obtained Fastq files were clipped and analysed with a locally installed version of the Galaxy platform. Sequences were mapped against the roe deer transcriptome (unpublished data) and annotated against human and bovine transcripts. Differentially expressed genes (DEG; false discovery rate <1%) were identified using EdgeR (https://bioconductor.org/packages/release/bioc/html/edgeR.html) in immature (IMM) and mature (M) oocytes from diapause (D) and nondiapause (ND) stages. Additionally, to evaluate the effects of maturation on oocyte transcript abundancy, DEG between IMM and M oocytes for D and ND were identified. Multidimensional scaling resulted in clustering according to oocyte types. Gene ontology terms for biological processes were assigned using ToppCluster tools. A total of 23066, 23022, 22438, and 22532 transcripts were detected for IMM D, M D, IMM ND and M ND oocytes, respectively. Using false discovery rate filtering, we found 333 and 288 DEG in immature and mature oocytes, respectively. Furthermore, maturation changed the oocyte expression profiles during D (2233 DEG) and ND periods (2589 DEG). Gene ontology classification revealed that most of the DEG in immature oocytes were involved in macromolecule catabolic process and oxidation-reduction process. For mature oocytes, DEG were mostly related to regulation of chromosome condensation and ER and Golgi vesicle-mediated transport. Additionally, the top 20 DEG from IMM D v. M D oocytes were related to mRNA splicing, mRNA metabolic process, and mRNA processing. These processes were not identified in the top 20 DEG from IMM ND v. M ND oocytes. These preliminary results suggest that oocyte transcriptome analysis could disclose new pathways implicated in oocyte competence and embryonic developmental arrest and activation stages.

scholarly journals Role of PB1 Midbody Remnant Creating Tethered Polar Bodies during Meiosis II

Genes ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1394
Author(s):  
Alex McDougall ◽  
Celine Hebras ◽  
Gerard Pruliere ◽  
David Burgess ◽  
Vlad Costache ◽  
...  
Keyword(s):  
Polar Body ◽  
Dynamic Imaging ◽  
Meiotic Spindle ◽  
Left Behind ◽  
Meiotic Chromosomes ◽  
Polar Bodies ◽  
The Future ◽  
Previous Round ◽  
Small Structure ◽  
Fertilized Egg

Polar body (PB) formation is an extreme form of unequal cell division that occurs in oocytes due to the eccentric position of the small meiotic spindle near the oocyte cortex. Prior to PB formation, a chromatin-centered process causes the cortex overlying the meiotic chromosomes to become polarized. This polarized cortical subdomain marks the site where a cortical protrusion or outpocket forms at the oocyte surface creating the future PBs. Using ascidians, we observed that PB1 becomes tethered to the fertilized egg via PB2, indicating that the site of PB1 cytokinesis directed the precise site for PB2 emission. We therefore studied whether the midbody remnant left behind following PB1 emission was involved, together with the egg chromatin, in defining the precise cortical site for PB2 emission. During outpocketing of PB2 in ascidians, we discovered that a small structure around 1 µm in diameter protruded from the cortical outpocket that will form the future PB2, which we define as the “polar corps”. As emission of PB2 progressed, this small polar corps became localized between PB2 and PB1 and appeared to link PB2 to PB1. We tested the hypothesis that this small polar corps on the surface of the forming PB2 outpocket was the midbody remnant from the previous round of PB1 cytokinesis. We had previously discovered that Plk1::Ven labeled midbody remnants in ascidian embryos. We therefore used Plk1::Ven to follow the dynamics of the PB1 midbody remnant during meiosis II. Plk1::Ven strongly labeled the small polar corps that formed on the surface of the cortical outpocket that created PB2. Following emission of PB2, this polar corps was rich in Plk1::Ven and linked PB2 to PB1. By labelling actin (with TRITC-Phalloidin) we also demonstrated that actin accumulates at the midbody remnant and also forms a cortical cap around the midbody remnant in meiosis II that prefigured the precise site of cortical outpocketing during PB2 emission. Phalloidin staining of actin and immunolabelling of anti-phospho aPKC during meiosis II in fertilized eggs that had PB1 removed suggested that the midbody remnant remained within the fertilized egg following emission of PB1. Dynamic imaging of microtubules labelled with Ens::3GFP, MAP7::GFP or EB3::3GFP showed that one pole of the second meiotic spindle was located near the midbody remnant while the other pole rotated away from the cortex during outpocketing. Finally, we report that failure of the second meiotic spindle to rotate can lead to the formation of two cortical outpockets at anaphase II, one above each set of chromatids. It is not known whether the midbody remnant of PB1 is involved in directing the precise location of PB2 since our data are correlative in ascidians. However, a review of the literature indicates that PB1 is tethered to the egg surface via PB2 in several species including members of the cnidarians, lophotrochozoa and echinoids, suggesting that the midbody remnant formed during PB1 emission may be involved in directing the precise site of PB2 emission throughout the invertebrates.

Human zygote morphological indicators of higher rate of arrest at the first cleavage stage

Zygote ◽  
2010 ◽  
Vol 19 (4) ◽  
pp. 339-344 ◽  
Author(s):  
Raquel Blanes Zamora ◽  
Rebeca Vaca Sánchez ◽  
Jonay González Pérez ◽  
Rubí Rodríguez Díaz ◽  
Delia Báez Quintana ◽  
...  
Keyword(s):  
Prospective Observational Study ◽  
Polar Body ◽  
Morphological Features ◽  
Chromosomal Anomalies ◽  
Dark Halo ◽  
Cleavage Stage ◽  
Developmental Arrest ◽  
Inverted Microscope ◽  
Culture Strategies ◽  
Nucleolar Precursor Bodies

SummaryA little studied aspect of developmental arrest (DA) in ART is zygote arrest (ZA). Etiologically, blockage at the first cleavage stage includes molecular and chromosomal anomalies, some of which manifest morphologically. Given considerations on embryo culture, transfer and cryopreservation, optimal zygote selection is very important. The aim of this study was to ascertain whether zygote morphological features were indicators of increased ZA. In this study we performed a prospective, observational study of 2105 zygotes obtained from consecutive patients who were undergoing IVF/ICSI treatment, of which 43 (2%) suffered ZA. Morphological features observed under the inverted microscope were qualitatively categorized: pronuclear size, nucleolar precursor bodies (NPB) alignment, light and dark halos, polar body placement and fragmentation observed at 16–18 h post-insemination. We compared these features in blocked versus cleaved zygotes at 48 h and found significant correlations (p < 0.05) between ZA and three features: the absence of a light halo (p = 0.001), the absence of a dark halo (p < 0.005), and non-aligned NPB (p < 0.05). We can say that certain morphological features are indicators of significantly increased zygote arrest. These findings may be of utility for optimal zygote selection and culture strategies, especially in countries under restrictive conditions.

Live birth after polar body array comparative genomic hybridization prediction of embryo ploidy—the future of IVF?

2010 ◽  
Vol 93 (3) ◽  
pp. 1006.e7-1006.e10 ◽  
Author(s):  
Simon Fishel ◽  
Anthony Gordon ◽  
Colleen Lynch ◽  
Ken Dowell ◽  
George Ndukwe ◽  
...  
Keyword(s):  
Comparative Genomic Hybridization ◽  
Live Birth ◽  
Array Comparative Genomic Hybridization ◽  
Polar Body ◽  
Comparative Genomic ◽  
Genomic Hybridization ◽  
The Future

scholarly journals Polar body transfer restores the developmental potential of oocytes to blastocyst stage in a case of repeated embryo fragmentation

2017 ◽  
Vol 34 (5) ◽  
pp. 563-571 ◽  
Author(s):  
Shuo-Ping Zhang ◽  
Chang-Fu Lu ◽  
Fei Gong ◽  
Ping-Yuan Xie ◽  
Liang Hu ◽  
...  
Keyword(s):  
Polar Body ◽  
Blastocyst Stage ◽  
Developmental Potential ◽  
Embryo Fragmentation

scholarly journals Mitochondrial replacement therapy and the “three parent baby”

SURG Journal ◽  
2017 ◽  
Vol 9 (1) ◽  
pp. 48-56 ◽  
Author(s):  
Suzanna Tai
Keyword(s):  
Mitochondrial Dna ◽  
Replacement Therapy ◽  
Polar Body ◽  
Genetic Material ◽  
Eukaryotic Cells ◽  
Mtdna Mutation ◽  
Donor Oocyte ◽  
Polar Bodies ◽  
Mitochondrial Replacement Therapy ◽  
Pronuclear Transfer

The mitochondria contained in eukaryotic cells have their own DNA, and heritable mutations in mitochondrial DNA (mtDNA) can cause a variety of disorders in humans. A new therapy, mitochondrial replacement therapy (MRT), is currently being developed to address these mitochondrial disorders by eliminating the mutated mtDNA from the germline. The two main MRT techniques are pronuclear transfer, conducted in the zygote after fertilization, and spindle-chromosomal complex transfer, conducted in the oocyte before fertilization. In pronuclear transfer, the pronuclei from a zygote affected by a mtDNA mutation are transferred to an enucleated normal zygote. In spindle-chromosomal complex transfer, the genetic material from an oocyte affected by a mtDNA mutation is inserted into the cytoplasm of a donor oocyte that contains healthy mitochondria. A third method, polar body genome transfer, attempts to increase the efficiency of the above techniques by using polar bodies to supply the genetic material. While MRT is legally and ethically controversial, it has recently been implemented successfully in a clinical setting.

scholarly journals Role of midbody remnant in meiosis II creating tethered polar bodies

2017 ◽  
Author(s):  
Alex McDougall ◽  
Celine Hebras ◽  
Gerard Pruliere ◽  
David Burgess ◽  
Vlad Costache ◽  
...  
Keyword(s):  
Polar Body ◽  
Dynamic Imaging ◽  
Meiotic Spindle ◽  
Left Behind ◽  
Meiotic Chromosomes ◽  
Polar Bodies ◽  
The Future ◽  
Previous Round ◽  
Ascidian Embryos

AbstractPolar body (PB) formation is an extreme form of unequal cell division that occurs in oocytes due to the eccentric position of the small meiotic spindle near the oocyte cortex. Prior to PB formation, a chromatin-centered process causes the cortex overlying the meiotic chromosomes to become polarized. This polarized cortical subdomain marks the site where a cortical protrusion or outpocket forms at the oocyte surface creating the future PBs. We observed that PB1 becomes tethered to the egg via PB2, indicating that the site of PB1 cytokinesis directed the precise site for PB2 emission. We therefore studied whether the midbody remnant left behind following PB1 emission was involved, together with the egg chromatin, in defining the precise cortical site for PB2 emission. During outpocketing of PB2 in ascidians, we discovered that a small corps around 1μm in diameter protruded from the center of the cortical outpocket that will form the future PB2, which we call the “polar corps”. During emission of PB2, this small polar corps became localized between PB2 and PB1 and appeared to link PB2 to PB1. We tested the hypothesis that this small polar corps on the surface of the forming PB2 was the midbody remnant from the previous round of PB1 cytokinesis. We had previously discovered that Plk1::Ven labeled midbody remnants in ascidian embryos. We therefore used Plk1::Ven to follow the dynamics of the PB1 midbody remnant during meiosis II. Plk1::Ven strongly labeled the small polar corps that formed on the surface of the cortical outpocket that created PB2. Following emission of PB2, this polar corps was rich in Plk1::Ven and linked PB2 to PB1. By labelling actin (with LifeAct::mCherry/GFP or TRITC-Phalloidin) we also demonstrated that actin accumulates at the midbody remnant and also forms a cortical cap around the midbody remnant in meiosis II that prefigured the precise site of cortical outpocketing during PB2 emission. Phalloidin staining of actin and immunolabelling of anti-phospho aPKC during meiosis II in eggs that had PB1 removed showed that the midbody remnant remained within the egg following emission of PB1. Dynamic imaging of microtubules labelled with Ens::3GFP, MAP7::GFP or EB3::3GFP showed that one pole of the second meiotic spindle was located near the midbody remnant while the other pole rotated away from the cortex during outpocketing. Finally, we report that failure of the second meiotic spindle to rotate can lead to the formation of two cortical outpockets at anaphase II, one above each set of chromatids. It is not known whether the midbody remnant of PB1 is involved in directing the precise location of PB2 in other species as in ascidians. However, a review of the literature indicates that PB1 is tethered to the egg surface via PB2 in a number of species including members of the cnidarians, lophotrochozoa and echinoids, suggesting that the midbody remnant formed during PB1 emission may be involved in directing the precise site of PB2 emission throughout the invertebrates.

Physiological perspectives of reduced tillering and stunting in the tiller inhibition (tin) mutant of wheat

2013 ◽  
Vol 40 (10) ◽  
pp. 977 ◽  
Author(s):  
Tesfamichael H. Kebrom ◽  
Richard A. Richards
Keyword(s):  
Low Temperatures ◽  
Cereal Crops ◽  
Physiological Basis ◽  
Developmental Arrest ◽  
Long Day ◽  
Reproductive Phase ◽  
The Future ◽  
Cereal Yields ◽  
Precocious Development

The number of tillers established in cereal crops far exceeds the number that end up being grain bearing at maturity. Improving the economy in tillering has been proposed to improve cereal yields in both favourable and unfavourable environments. The tiller inhibition mutant (tin) is potentially useful for breeding varieties with a greater economy of tillering. However, its tendency to stunting under long day and low temperatures has limited its use. Recently, the inhibition of tillering in tin has been linked to precocious development of solid basal internodes that compete for sucrose and possibly other resources with the growing tiller buds leading to their developmental arrest. Although the physiological basis of stunting in tin is unknown, both inhibition of tillering and stunting begin during the transition from vegetative to reproductive phase indicating a common physiological basis for both. In this review, we provide overall perspectives for the physiological basis of tiller inhibition and stunting in tin and suggest the direction of research in the future.

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