Design of novel oocyte activation methods: The role of zinc

Author(s):  
Kyungjun Uh ◽  
Alayna Hay ◽  
Paula Chen ◽  
Emily Reese ◽  
Kiho Lee

Abstract Oocyte activation occurs at the time of fertilization and is a series of cellular events initiated by intracellular Ca2+ increases. Consequently, oocytes are alleviated from their arrested state in meiotic metaphase II (MII), allowing for the completion of meiosis. Oocyte activation is also an essential step for somatic cell nuclear transfer (SCNT) and an important tool to overcome clinical infertility. Traditional artificial activation methods aim to mimic the intracellular Ca2+ changes which occur during fertilization. Recent studies emphasize the importance of cytoplasmic Zn2+ on oocyte maturation and the completion of meiosis, thus suggesting artificial oocyte activation approaches that are centered around the concentration of available Zn2+in oocytes. Depletion of intracellular Zn2+ in oocytes with heavy metal chelators leads to successful oocyte activation in the absence of cellular Ca2+ changes, indicating that successful oocyte activation does not always depends on intracellular Ca2+ increases. Current findings lead to new approaches to artificially activate mammalian oocytes by reducing available Zn2+ contents, and the approaches improve the outcome of oocyte activation when combined with existing Ca2+ based oocyte activation methods. Here, we review the important role of Ca2+ and Zn2+ in mammalian oocyte activation and development of novel oocyte activation approaches based on Zn2+ availability.

1998 ◽  
Vol 10 (8) ◽  
pp. 599 ◽  
Author(s):  
Zoltán Macháty ◽  
Randall S. Prather

The technique of nuclear transfer can have enormous applications in the fields of agriculture and biomedicine. This is especially true if a cell line that has been transformed can be used as a source of nuclei for the nuclear transfer. One major aspect of the nuclear transfer procedures is that of oocyte activation. Without oocyte activation the transferred nucleus would never progress to the first interphase. It is therefore of utmost importance that the oocyte be activated in a fashion that is as normal as fertilization. The inability to obtain development after artificial activation of pig oocytes has been a limiting factor in the application of the nuclear transfer technology. Recently, a number of techniques have been developed that result in blastocyst stage embryos after oocyte maturation in vitro and artificial activation. The theories behind normal oocyte activation are reviewed as well as a number of methods of artificial oocyte activation. It is anticipated that such a review will provide the basis for the development of additional methods that are as efficient, or more efficient, at activating the unfertilized oocyte.


2018 ◽  
Vol 46 (4) ◽  
pp. 797-806 ◽  
Author(s):  
Jessica R. Sanders ◽  
Keith T. Jones

Initiated by luteinizing hormone and finalized by the fertilizing sperm, the mammalian oocyte completes its two meiotic divisions. The first division occurs in the mature Graafian follicle during the hours preceding ovulation and culminates in an extreme asymmetric cell division and the segregation of the two pairs of homologous chromosomes. The newly created mature egg rearrests at metaphase of the second meiotic division prior to ovulation and only completes meiosis following a Ca2+ signal initiated by the sperm at gamete fusion. Here, we review the cellular events that govern the passage of the oocyte through meiosis I with a focus on the role of the spindle assembly checkpoint in regulating its timing. In meiosis II, we examine how the egg achieves its arrest and how the fertilization Ca2+ signal allows the initiation of embryo development.


2020 ◽  
Vol 19 (5) ◽  
pp. 77-85
Author(s):  
Yu.Yu. Gromenko ◽  
◽  
E.F. Galimova ◽  
D.D. Gromenko ◽  
K.Sh. Galimov ◽  
...  

Fertilization and embryogenesis in mammals are initiated by a series of molecular events called ‘oocyte activation.’ This process includes a number of specific fluctuations of calcium ions in the cell with the involvement of specific phospholipase C ζ (PLCζ), an enzyme of spermatozoa introduced into the ooplasm during gamete fusion and recognized as the main factor responsible for inducing oocyte activation. Substantial biochemical and clinical evidence supports the role of PLCζ in this fundamental process, which is very important for the diagnosis and treatment of infertility. This literature review aims to provide some insight in the structure, mechanism of action, and regulation of PLCζ activity in healthy individuals and people with pathological conditions. Oocyte activation deficiency is associated with abnormalities in the structure, expression, and location of this enzyme in spermatozoa. Artificial activation of oocytes using ionophores, which is the only therapeutic option currently available for patients with its insufficiency, is being debated, especially in terms of its potential epigenetic effects on the embryo. Therefore, interest towards the development of human recombinant PLCζ as an alternative treatment is understandable. Researchers are currently discussing the possibility of diagnostic and clinical application of this enzyme to overcome male infertility associated with oocyte activation deficiency, as well as general aspects of this pathology. Key words: oocyte activation, infertility, calcium ions, phospholipase C ζ


2014 ◽  
Author(s):  
Satanay Hubrack ◽  
Ethel Adap ◽  
Stefan Feske ◽  
Khaled Machaca

Reproduction ◽  
2018 ◽  
Vol 155 (2) ◽  
pp. R105-R119 ◽  
Author(s):  
Minerva Ferrer-Buitrago ◽  
Davina Bonte ◽  
Petra De Sutter ◽  
Luc Leybaert ◽  
Björn Heindryckx

Oocyte activation is a calcium (Ca2+)-dependent process that has been investigated in depth, in particular, regarding its impact on assisted reproduction technology (ART). Following a standard model of signal transduction, Ca2+drives the meiotic progression upon fertilization in all species studied to date. However, Ca2+changes during oocyte activation are species specific, and they can be classified in two modalities based on the pattern defined by the Ca2+signature: a single Ca2+transient (e.g. amphibians) or repetitive Ca2+transients called Ca2+oscillations (e.g. mammals). Interestingly, assisted oocyte activation (AOA) methods have highlighted the ability of mammalian oocytes to respond to single Ca2+transients with normal embryonic development. In this regard, there is evidence supporting that cellular events during the process of oocyte activation are initiated by different number of Ca2+oscillations. Moreover, it was proposed that oocyte activation and subsequent embryonic development are dependent on the total summation of the Ca2+peaks, rather than to a specific frequency pattern of Ca2+oscillations. The present review aims to demonstrate the complexity of mammalian oocyte activation by describing the series of Ca2+-linked physiological events involved in mediating the egg-to-embryo transition. Furthermore, mechanisms of AOA and the limitations and benefits associated with the application of different activation agents are discussed.


2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Chiharu Uchida

Retinoblastoma protein (pRB) interacts with E2F and other protein factors to play a pivotal role in regulating the expression of target genes that induce cell cycle arrest, apoptosis, and differentiation. pRB controls the local promoter activity and has the ability to change the structure of nucleosomes and/or chromosomes via histone modification, epigenetic changes, chromatin remodeling, and chromosome organization. Functional inactivation of pRB perturbs these cellular events and causes dysregulated cell growth and chromosome instability, which are hallmarks of cancer cells. The role of pRB in regulation of nucleosome/chromatin structures has been shown to link to tumor suppression. This review focuses on the ability of pRB to control nucleosome/chromatin structures via physical interactions with histone modifiers and chromatin factors and describes cancer therapies based on targeting these protein factors.


Nutrients ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 1180
Author(s):  
Kayvan Khoramipour ◽  
Karim Chamari ◽  
Amirhosein Ahmadi Hekmatikar ◽  
Amirhosein Ziyaiyan ◽  
Shima Taherkhani ◽  
...  

Adiponectin (a protein consisting of 244 amino acids and characterized by a molecular weight of 28 kDa) is a cytokine that is secreted from adipose tissues (adipokine). Available evidence suggests that adiponectin is involved in a variety of physiological functions, molecular and cellular events, including lipid metabolism, energy regulation, immune response and inflammation, and insulin sensitivity. It has a protective effect on neurons and neural stem cells. Adiponectin levels have been reported to be negatively correlated with cancer, cardiovascular disease, and diabetes, and shown to be affected (i.e., significantly increased) by proper healthy nutrition. The present review comprehensively overviews the role of adiponectin in a range of diseases, showing that it can be used as a biomarker for diagnosing these disorders as well as a target for monitoring the effectiveness of preventive and treatment interventions.


2021 ◽  
Vol 10 (2) ◽  
pp. 139-161
Author(s):  
Núria Almiron ◽  
Laura Fernández

In this paper we argue that adopting critical animal studies perspectives in critical public relations can not only be very fruitful, but that it is also a necessity if the aims of the latter are to be achieved. To this end, this text introduces the challenges and opportunities that the field of critical animal studies brings to critical public relations studies. First, a short explanation of what critical animal studies is and why it can contribute to critical public relations studies is provided. Then the main fields of research where this contribution can be most relevant are discussed, including ethics, discourse studies and political economy. The final aim of this theoretical paper is to expand research within the field of critical public relations by including a critical animal studies approach. Eventually, the authors suggest that embracing the animal standpoint in critical public relations is an essential step to furthering the study of power, hegemony, ideology, propaganda or social change and to accomplishing the emancipatory role of research.


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