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Cold Spring Harbor Protocols Mar 2021Nearly a century ago, studies by Lancelot Hogben and others demonstrated that ovulation in female can be induced via injection of mammalian gonadotropins into the...
Nearly a century ago, studies by Lancelot Hogben and others demonstrated that ovulation in female can be induced via injection of mammalian gonadotropins into the dorsal lymph sac, allowing for egg production throughout the year independent of the normal reproductive cycles. Hormonally induced females are capable of producing thousands of eggs in a single spawning, which can then be fertilized to generate embryos or used as a substrate for generation of egg extracts. The protocol for induction of ovulation and subsequent egg collection is straightforward and robust, yet some of its details may vary among laboratories based on prior training, availability of necessary reagents, or the experimental objectives. As the goal of this protocol is not to describe every single variation possible for acquiring eggs but to provide a simple and clear description that can be easily applied by researchers with no prior working experience with , we focus on describing the method we use at the National Resource-that is, inducing ovulation in via dorsal lymph sac injection of gonadotropic hormones and the stimulation of egg laying through application of gentle pressure to the females.
Topics: Animals; Female; Gonadotropins; Ovum; Physiology; Xenopus laevis
PubMed: 33272976
DOI: 10.1101/pdb.prot106203 -
Current Topics in Developmental Biology 2013Egg activation is the final transition that an oocyte goes through to become a developmentally competent egg. This transition is usually triggered by a calcium-based... (Review)
Review
Egg activation is the final transition that an oocyte goes through to become a developmentally competent egg. This transition is usually triggered by a calcium-based signal that is often, but not always, initiated by fertilization. Activation encompasses a number of changes within the egg. These include changes to the egg's membranes and outer coverings to prevent polyspermy and to support the developing embryo, as well as resumption and completion of the meiotic cell cycle, mRNA polyadenylation, translation of new proteins, and the degradation of specific maternal mRNAs and proteins. The transition from an arrested, highly differentiated cell, the oocyte, to a developmentally active, totipotent cell, the activated egg or embryo, represents a complete change in cellular state. This is accomplished by altering ion concentrations and by widespread changes in both the proteome and the suite of mRNAs present in the cell. Here, we review the role of calcium and zinc in the events of egg activation, and the importance of macromolecular changes during this transition. The latter include the degradation and translation of proteins, protein posttranslational regulation through phosphorylation, and the degradation, of maternal mRNAs.
Topics: Animals; Humans; Ions; Models, Biological; Oocytes; Ovum; Proteome; RNA Stability
PubMed: 23287037
DOI: 10.1016/B978-0-12-416024-8.00010-6 -
International Journal of Molecular... Mar 2021Mammalian oocytes are surrounded by an extracellular coat called the zona pellucida (ZP), which, from an evolutionary point of view, is the most ancient of the coats... (Review)
Review
Mammalian oocytes are surrounded by an extracellular coat called the zona pellucida (ZP), which, from an evolutionary point of view, is the most ancient of the coats that envelope vertebrate oocytes and conceptuses. This matrix separates the oocyte from cumulus cells and is responsible for species-specific recognition between gametes, preventing polyspermy and protecting the preimplantation embryo. The ZP is a dynamic structure that shows different properties before and after fertilization. Until very recently, mammalian ZP was believed to be composed of only three glycoproteins, ZP1, ZP2 and ZP3, as first described in mouse. However, studies have revealed that this composition is not necessarily applicable to other mammals. Such differences can be explained by an analysis of the molecular evolution of the ZP gene family, during which ZP genes have suffered pseudogenization and duplication events that have resulted in differing models of ZP protein composition. The many discoveries made in recent years related to ZP composition and evolution suggest that a compilation would be useful. Moreover, this review analyses ZP biosynthesis, the role of each ZP protein in different mammalian species and how these proteins may interact among themselves and with other proteins present in the oviductal lumen.
Topics: Animals; Biomarkers; Cell Communication; Evolution, Molecular; Female; Gene Expression Regulation, Developmental; Male; Mammals; Oocytes; Ovum; Protein Transport; Spermatozoa; Zona Pellucida; Zona Pellucida Glycoproteins
PubMed: 33806989
DOI: 10.3390/ijms22063276 -
Cells Aug 2021Self-organization of and by the cytoskeleton is central to the biology of the cell. Since their introduction in the early 1980s, cytoplasmic extracts derived from the... (Review)
Review
Self-organization of and by the cytoskeleton is central to the biology of the cell. Since their introduction in the early 1980s, cytoplasmic extracts derived from the eggs of the African clawed-frog, , have flourished as a major experimental system to study the various facets of cytoskeleton-dependent self-organization. Over the years, the many investigations that have used these extracts uniquely benefited from their simplified cell cycle, large experimental volumes, biochemical tractability and cell-free nature. Here, we review the contributions of egg extracts to our understanding of the cytoplasmic aspects of self-organization by the microtubule and the actomyosin cytoskeletons as well as the importance of cytoskeletal filaments in organizing nuclear structure and function.
Topics: Actin Cytoskeleton; Animals; Cell Cycle; Cell Division; Cytoplasm; Cytoskeleton; Microtubules; Oocytes; Ovum; Xenopus laevis
PubMed: 34571847
DOI: 10.3390/cells10092197 -
Nature Chemistry Jul 2021Mammalian oocytes undergo major changes in zinc content and localization to be fertilized, the most striking being the rapid exocytosis of over 10 billion zinc ions in...
Mammalian oocytes undergo major changes in zinc content and localization to be fertilized, the most striking being the rapid exocytosis of over 10 billion zinc ions in what are known as zinc sparks. Here, we report that fertilization of amphibian Xenopus laevis eggs also initiates a zinc spark that progresses across the cell surface in coordination with dynamic calcium waves. This zinc exocytosis is accompanied by a newly recognized loss of intracellular manganese. Synchrotron-based X-ray fluorescence and analytical electron microscopy reveal that zinc and manganese are sequestered in a system of cortical granules that are abundant at the animal pole. Through electron-nuclear double-resonance studies, we rule out Mn complexation with phosphate or nitrogenous ligands in intact eggs, but the data are consistent with a carboxylate coordination environment. Our observations suggest that zinc and manganese fluxes are a conserved feature of fertilization in vertebrates and that they function as part of a physiological block to polyspermy.
Topics: Animals; Embryo, Nonmammalian; Exocytosis; Fertilization; Metals, Heavy; Ovum; Xenopus laevis
PubMed: 34155376
DOI: 10.1038/s41557-021-00705-2 -
Trends in Molecular Medicine Mar 2018Even with the benefit of assisted reproductive technologies (ART), many women are unable to conceive and deliver healthy offspring. One common cause of infertility is... (Review)
Review
Even with the benefit of assisted reproductive technologies (ART), many women are unable to conceive and deliver healthy offspring. One common cause of infertility is the inability to produce eggs capable of contributing to live birth. This can occur despite standard-of-care treatment to maximize the recovery of eggs from growing ovarian follicles. Dormant primordial follicles in the human ovary are a 'reserve ' that can be exploited clinically to overcome this problem. We discuss how controlling primordial follicle growth activation (PFGA) can produce increased numbers of high-quality eggs available for fertility treatment(s). We consider the state of the art in interventions used to control PFGA, and consider genetic and epigenetic strategies on the horizon that might improve compromised oocyte quality to increase live births.
Topics: Animals; Female; Humans; Infertility; Oocytes; Ovarian Follicle; Ovum; Pregnancy; Reproductive Techniques, Assisted
PubMed: 29452791
DOI: 10.1016/j.molmed.2018.01.008 -
Emerging Infectious Diseases Aug 2018Occasionally, abnormal forms of parasitic helminth eggs are detected during routine diagnostics. This finding can prove problematic in diagnosis because morphologic... (Review)
Review
Occasionally, abnormal forms of parasitic helminth eggs are detected during routine diagnostics. This finding can prove problematic in diagnosis because morphologic analysis based on tightly defined measurements is the primary method used to identify the infecting species and molecular confirmation of species is not always feasible. We describe instances of malformed nematode eggs (primarily from members of the superfamily Ascaridoidea) from human clinical practice and experimental trials on animals. On the basis of our observations and historical literature, we propose that unusual development and morphology of nematode and trematode eggs are associated with early infection. Further observational studies and experimentation are needed to identify additional factors that might cause abnormalities in egg morphology and production. Abnormal egg morphology can be observed early in the course of infection and can confound accurate diagnosis of intestinal helminthiases.
Topics: Animals; Helminthiasis; Humans; Intestinal Diseases, Parasitic; Nematoda; Ovum; Trematoda
PubMed: 30014830
DOI: 10.3201/eid2408.180560 -
Parasites & Vectors Oct 2021The diseases for which Aedes aegypti is a vector are worrisome. The high vector competence of this mosquito, as well as its anthropophilia and ability to adapt to the...
BACKGROUND
The diseases for which Aedes aegypti is a vector are worrisome. The high vector competence of this mosquito, as well as its anthropophilia and ability to adapt to the urban environment, allows it to exploit many habitats, making its prevention an arduous task. Despite current disease control measures focused on the mosquito, the effectiveness in containing its dispersion still requires improvement; thus greater knowledge about this insect is fundamental.
METHODS
Aedes aegypti egg morphology and embryonic development were analyzed from eggs of the insectary of the Institute of Biomedical Sciences of the University of São Paulo. Optical (light and confocal) and electronic (transmission and scanning) microscopy were used to analyze the morphological and ultrastructural features of the eggs. Embryos were observed in the initial (0-20.5 h after egg-laying), intermediate (20.6-40.1 h after egg-laying), and final (40.2-61.6 h) stages of development, and kept at a temperature of 28 °C ± 1 °C until collection for processing.
RESULTS
Eggs of Ae. aegypti were whitish at the time of oviposition, and then quickly became black. The egg length was 581.45 ± 39.73 μm and the width was 175.36 ± 11.59. Access to the embryo was difficult due to the egg morphology, point of embryonic development, and difficult permeability of the exochorion (mainly in fixation). Only about 5% of the collected eggs were successfully processed. In the initial stage of embryonic development, characteristics suggestive of intense cellular activity were found. In the intermediate stage, the beginning of the segmentation process was evident. In the final phase, it was possible to differentiate the cephalic region and the thoracic and abdominal segments.
CONCLUSION
The chorion was found to be an important protective barrier and a limiting factor for the evaluation of the embryos and mosquito embryonic cells, indicating that further studies need to be carried out to identify the reason that this occurs.
Topics: Aedes; Animals; Dengue; Embryonic Development; Female; Mosquito Vectors; Oviposition; Ovum
PubMed: 34645492
DOI: 10.1186/s13071-021-05024-6 -
Integrative and Comparative Biology Jul 2014Transgenerational epigenetics, the study of non-genetic transfer of information from one generation to the next, has gained much attention in the past few decades due to... (Review)
Review
Transgenerational epigenetics, the study of non-genetic transfer of information from one generation to the next, has gained much attention in the past few decades due to the fact that, in many instances, epigenetic processes outweigh direct genetic processes in the manifestation of aberrant phenotypes across several generations. Maternal effects, or the influences of maternal environment, phenotype, and/or genotype on offsprings' phenotypes, independently of the offsprings' genotypes, are a subcategory of transgenerational epigenetics. Due to the intimate role of the mother during early development in animals, there is much interest in investigating the means by which maternal effects can shape the individual. Maternal effects are responsible for cellular organization, determination of the body axis, initiation and maturation of organ systems, and physiological performance of a wide variety of species and biological systems. The cardiovascular system is the first to become functional and can significantly influence the development of other organ systems. Thus, it is important to elucidate the role of maternal effects in cardiovascular development, and to understand its impact on adult cardiovascular health. Topics to be addressed include: (1) how and when do maternal effects change the developmental trajectory of the cardiovascular system to permanently alter the adult's cardiovascular phenotype, (2) what molecular mechanisms have been associated with maternally induced cardiovascular phenotypes, and (3) what are the evolutionary implications of maternally mediated changes in cardiovascular phenotype?
Topics: Biological Evolution; Cardiovascular System; Epigenesis, Genetic; Female; Humans; Inheritance Patterns; Maternal-Fetal Exchange; Morphogenesis; Ovum; Phenotype; Pregnancy
PubMed: 24813463
DOI: 10.1093/icb/icu031 -
Poultry Science Jun 2020The effects of storage temperature (4°C, 25°C, and 35°C) on sensory quality, physicochemical properties, texture, molecular forces, flavor, and microbial indexes of...
The effects of storage temperature (4°C, 25°C, and 35°C) on sensory quality, physicochemical properties, texture, molecular forces, flavor, and microbial indexes of preserved eggs were studied. The results showed that the sensory quality, weight loss rate, pH, and color of preserved eggs were significantly different at different storage temperatures (P < 0.05). Compared with high temperature and normal temperature storage, low temperature storage reduced weight loss rate by 55.15 and 64.1%, respectively, improved the sensory score (P < 0.05), inhibited the reduction of pH and the increase of total volatile base nitrogen (P < 0.05), and decreased the change of color (P < 0.05). During storage, there was no difference in the springiness of preserved egg white stored at different temperatures (P > 0.05). Hardness and chewiness at 3 different temperatures increased first and then decreased, and low temperature significantly inhibited the progress of these changes to a certain extent (P < 0.05). The content of ionic bond in egg white first decreased and then increased, and content of disulfide bond increased first and then decreased. Content of ionic bond in yolk decreased all the time, and high temperature could promote this change. Whatever the temperature was, the content of free amino acids in preserved egg white and yolk increased first and then decreased, and the total content of amino acids stored at different temperatures was significantly different (P < 0.05). The content of free fatty acids in yolk decreased. At the end of storage, no microorganisms were detected in 3 temperatures during the storage period of 84 D. The results showed that low temperature storage is more conducive for preservation of preserved eggs.
Topics: Animals; Chickens; Cold Temperature; Eggs; Food Preservation; Food Quality; Hot Temperature; Ovum
PubMed: 32475451
DOI: 10.1016/j.psj.2020.01.020