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Methods in Molecular Biology (Clifton,... 2020A transgenic mouse carries within its genome an artificial DNA construct (transgene) that is deliberately introduced by an experimentalist. These animals are widely used...
A transgenic mouse carries within its genome an artificial DNA construct (transgene) that is deliberately introduced by an experimentalist. These animals are widely used to understand gene function and protein function. When addressing the history of transgenic mouse technology, it is apparent that a number of basic science research areas laid the groundwork for success. These include reproductive science, genetics and molecular biology, and micromanipulation and microscopy equipment. From reproductive physiology came applications on how to optimize mouse breeding, how to superovulate mice to produce zygotes for DNA microinjection or preimplantation embryos for combination with embryonic stem (ES) cells, and how to return zygotes and embryos to a pseudopregnant surrogate dam for gestation and birth. From developmental biology, it was learned how to micromanipulate embryos for morula aggregation and blastocyst microinjection and how to establish germline competent ES cells. From genetics came the foundational principles governing the inheritance of genes, the interactions of gene products, and an understanding of the phenotypic consequences of genetic mutations. From molecular biology came a panoply of tools and reagents that are used to clone DNA transgenes, to detect the presence of transgenes, to assess gene expression by measuring transcription, and to detect proteins in cells and tissues. Technical advances in light microscopes, micromanipulators, micropipette pullers, and ancillary equipment made it possible for experimentalists to insert thin glass needles into zygotes or embryos under controlled conditions to inject DNA solutions or ES cells. To fully discuss the breadth of contributions of these numerous scientific disciplines to a comprehensive history of transgenic science is beyond the scope of this work. Examples will be used to illustrate scientific developments central to the foundation of transgenic technology and that are in use today.
Topics: Animals; Embryo Transfer; Embryonic Stem Cells; Gene Transfer Techniques; History, 20th Century; History, 21st Century; Mice; Mice, Transgenic; Microinjections; Transgenes; Zygote
PubMed: 31512203
DOI: 10.1007/978-1-4939-9837-1_1 -
JBRA Assisted Reproduction May 2020The mitochondria are intracellular organelles, and just like the cell nucleus they have their own genome. They are extremely important for normal body functioning and... (Review)
Review
The mitochondria are intracellular organelles, and just like the cell nucleus they have their own genome. They are extremely important for normal body functioning and are responsible for ATP production - the main energy source for the cell. Mitochondrial diseases are associated with mutations in mitochondrial DNA and are inherited exclusively from the mother. They can affect organs that depend on energy metabolism, such as skeletal muscles, the cardiac system, the central nervous system, the endocrine system, the retina and liver, causing various incurable diseases. Mitochondrial replacement techniques provide women with mitochondrial defects a chance to have normal biological children. The goal of such treatment is to reconstruct functional oocytes and zygotes, in order to avoid the inheritance of mutated genes; for this the nuclear genome is withdrawn from an oocyte or zygotes, which carries mitochondrial mutations, and is implanted in a normal anucleated cell donor. Currently, the options of a couple to prevent the transmission of mitochondrial diseases are limited, and mitochondrial donation techniques provide women with mitochondrial defects a chance to have normal children. The nuclear genome can be transferred from oocytes or zygotes using techniques such as pronuclear transfer, spindle transfer, polar body transfer and germinal vesicle transfer. This study presents a review of developed mitochondrial substitution techniques, and its ability to prevent hereditary diseases.
Topics: Adult; DNA, Mitochondrial; Female; Genome, Mitochondrial; Humans; Male; Mitochondrial Diseases; Mitochondrial Replacement Therapy; Mutation; Oocytes; Parents; Zygote
PubMed: 32073245
DOI: 10.5935/1518-0557.20190086 -
The International Journal of... 2020Sexually reproducing organisms generate male and female haploid gametes, which meet and fuse at fertilization to produce a diploid zygote. The evolutionary process of... (Review)
Review
Sexually reproducing organisms generate male and female haploid gametes, which meet and fuse at fertilization to produce a diploid zygote. The evolutionary process of speciation is achieved and maintained by ensuring that gametes undergo productive fusion only within a species. In animals, hybrids from cross-species fertilization events may develop normally, but are usually sterile (Fitzpatrick, 2004). Metazoan sperm and eggs have several features to ensure that the gametes, which have evolved independently and also in conflict with each other, are competent to undergo fertilization (Firman, 2018). Fertilization is a specific process that is ideally supposed to result in randomized fusion of compatible egg and sperm. Here, I will discuss key processes driven by maternal factors in the egg that dictate earliest stages of gamete recognition, gamete choice and fusion in metazoans.
Topics: Animals; Biological Evolution; Female; Germ Cells; Male; Maternal Inheritance; Reproduction; Sperm-Ovum Interactions; Zygote
PubMed: 32659006
DOI: 10.1387/ijdb.190156sn -
Cellular and Molecular Life Sciences :... May 2018The maternal-to-zygotic transition (MZT) is essential for the developmental control handed from maternal products to newly synthesized zygotic genome in the earliest... (Review)
Review
The maternal-to-zygotic transition (MZT) is essential for the developmental control handed from maternal products to newly synthesized zygotic genome in the earliest stages of embryogenesis, including maternal component (mRNAs and proteins) degradation and zygotic genome activation (ZGA). Various protein post-translational modifications have been identified during the MZT, such as phosphorylation, methylation and ubiquitination. Precise post-translational regulation mechanisms are essential for the timely transition of early embryonic development. In this review, we summarize recent progress regarding the molecular mechanisms underlying post-translational regulation of maternal component degradation and ZGA during the MZT and discuss some important issues in the field.
Topics: Animals; Embryonic Development; Female; Gene Expression Regulation, Developmental; Humans; Pregnancy; Protein Processing, Post-Translational; RNA, Messenger, Stored; Zygote
PubMed: 29427077
DOI: 10.1007/s00018-018-2750-y -
Fly Dec 2022The development of all animal embryos is initially directed by the gene products supplied by their mothers. With the progression of embryogenesis, the embryo's genome is... (Review)
Review
The development of all animal embryos is initially directed by the gene products supplied by their mothers. With the progression of embryogenesis, the embryo's genome is activated to command subsequent developments. This transition, which has been studied in many model animals, is referred to as the Maternal-to-Zygotic Transition (MZT). In many organisms, including flies, nematodes, and sea urchins, genes involved in Notch signaling are extensively influenced by the MZT. This signaling pathway is highly conserved across metazoans; moreover, it regulates various developmental processes. Notch signaling defects are commonly associated with various human diseases. The maternal contribution of its factors was first discovered in flies. Subsequently, several genes were identified from mutant embryos with a phenotype similar to mutants only upon the removal of the maternal contributions. Studies on these maternal genes have revealed various novel steps in the cascade of Notch signal transduction. Among these genes, and have been functionally characterized in recent studies. Therefore, in this review, we will focus on the roles of these two maternal genes in Notch signaling and discuss future research directions on its maternal function.
Topics: Humans; Animals; Gene Expression Regulation, Developmental; Zygote; Embryonic Development; Signal Transduction; Genome
PubMed: 36346359
DOI: 10.1080/19336934.2022.2139981 -
Development (Cambridge, England) Jul 2020During development, cells need to make decisions about their fate in order to ensure that the correct numbers and types of cells are established at the correct time and... (Review)
Review
During development, cells need to make decisions about their fate in order to ensure that the correct numbers and types of cells are established at the correct time and place in the embryo. Such cell fate decisions are often classified as deterministic or stochastic. However, although these terms are clearly defined in a mathematical sense, they are sometimes used ambiguously in biological contexts. Here, we provide some suggestions on how to clarify the definitions and usage of the terms stochastic and deterministic in biological experiments. We discuss the frameworks within which such clear definitions make sense and highlight when certain ambiguity prevails. As an example, we examine how these terms are used in studies of neuronal cell fate decisions and point out areas in which definitions and interpretations have changed and matured over time. We hope that this Review will provide some clarification and inspire discussion on the use of terminology in relation to fate decisions.
Topics: Animals; Cell Differentiation; Cell Lineage; Central Nervous System; Models, Biological; Neocortex; Neurons; Stochastic Processes; Zygote
PubMed: 32669276
DOI: 10.1242/dev.181495 -
Methods in Molecular Biology (Clifton,... 2022Creating mouse models of human genetic disease (Gurumurthy and Lloyd, Dis Models Mech 12(1):dmm029462, 2019) and livestock trait (Schering et al. Arch Physiol Biochem...
Creating mouse models of human genetic disease (Gurumurthy and Lloyd, Dis Models Mech 12(1):dmm029462, 2019) and livestock trait (Schering et al. Arch Physiol Biochem 121(5):194-205, 2015; Habiela et al. J Gen Virol 95 (Pt 11):2329-2345, 2014) have been proven to be a useful tool for understanding the mechanism behind the phenotypes and fundamental and applied research in livestock. A single base pair deletion of prolactin receptor (PRLR) has an impact on hair morphology phenotypes beyond its classical roles in lactation in cattle, the so-called slick cattle (Littlejohn et al. Nat Commun 5:5861, 2014). Here, we generate a knock-in mouse model by targeting the specific locus of PRLR gene using Cas9-mediated genome editing via homology-directed repair (HDR) in mouse zygotes. The mouse model carrying the identical PRLR mutation in slick cattle may provide a useful animal model to study the pathway of thermoregulation and the mechanism of heat-tolerance in the livestock.
Topics: Animals; CRISPR-Cas Systems; Cattle; Female; Gene Editing; Hot Temperature; Mice; Recombinational DNA Repair; Zygote
PubMed: 35696038
DOI: 10.1007/978-1-0716-2301-5_14 -
Cell and Tissue Research Jan 2016The origin recognition complex (ORC) proteins, ORC1-6, are the first known proteins that bind DNA replication origins to mark the competency for the initiation of DNA... (Review)
Review
The origin recognition complex (ORC) proteins, ORC1-6, are the first known proteins that bind DNA replication origins to mark the competency for the initiation of DNA synthesis. These proteins have complex mechanisms of assembly into the ORC complex and unexpected localizations in the mitotic chromosomes, cytoplasm, and nuclear structures. The mammalian zygote is a potentially important model that may contribute to our understanding of the mechanisms and features influencing origin establishment and in the identification of other functions of the ORC proteins. Together with expected localizations to the chromatin during G1, we found an unexpected distribution in the cytoplasm that appeared to accumulate ORC proteins suggesting potential roles for ORC subunits in mitosis and chromatin segregation. ORC1, 2, 3, and 5 all localize to the area between the separating maternal chromosomes shortly after fertilization. ORC4 forms a cage around the set of chromosomes that will be extruded during polar body formation before it binds to the chromatin shortly before zygotic DNA replication. These data suggest that the ORC proteins may also play roles in preparing the cell for DNA replication in addition to their direct role in establishing functional replication origins.
Topics: Animals; DNA Replication; Female; Humans; Male; Origin Recognition Complex; Spermatozoa; Zygote
PubMed: 26453397
DOI: 10.1007/s00441-015-2296-3 -
Current Opinion in Plant Biology Feb 2019Plant embryogenesis initiates with the fusion of sperm and egg cell, and completes the generation of the basic outline of the future plant. Here, we summarize the recent... (Review)
Review
Plant embryogenesis initiates with the fusion of sperm and egg cell, and completes the generation of the basic outline of the future plant. Here, we summarize the recent findings about the signaling cascade triggering the zygotic transcription, and the intracellular events and regulatory factors involved in the formation of the two major body axes. We highlight the lack of systematic de novo transcriptional activation in the zygote, and emphasize the importance of cytoskeletal reorganization to polarize the zygote and control the first asymmetric division that establishes the apical-basal axis. Finally, the limited knowledge of mechanisms that control the cell divisions separating the inner and outer cell layers is summarized and we propose approaches to enhance our understanding of basic principles of plant embryogenesis.
Topics: Body Patterning; Gene Expression Regulation, Plant; Models, Biological; Seeds; Transcription, Genetic; Zygote
PubMed: 30223185
DOI: 10.1016/j.pbi.2018.08.005 -
Molecular Reproduction and Development Sep 2017Genome editing in pigs has tremendous practical applications for biomedicine. The advent of genome editing technology, with its use of site-specific nucleases-including... (Review)
Review
Genome editing in pigs has tremendous practical applications for biomedicine. The advent of genome editing technology, with its use of site-specific nucleases-including ZFNs, TALENs, and the CRISPR/Cas9 system-has popularized targeted zygote genome editing via one-step microinjection in several mammalian species. Here, we review methods to optimize the developmental competence of genome-edited porcine embryos and strategies to improve the zygote genome-editing efficiency in pigs.
Topics: Animals; Animals, Genetically Modified; CRISPR-Cas Systems; Gene Editing; Swine; Zygote
PubMed: 28471514
DOI: 10.1002/mrd.22829