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Cell Mar 2024Following the fertilization of an egg by a single sperm, the egg coat or zona pellucida (ZP) hardens and polyspermy is irreversibly blocked. These events are associated...
Following the fertilization of an egg by a single sperm, the egg coat or zona pellucida (ZP) hardens and polyspermy is irreversibly blocked. These events are associated with the cleavage of the N-terminal region (NTR) of glycoprotein ZP2, a major subunit of ZP filaments. ZP2 processing is thought to inactivate sperm binding to the ZP, but its molecular consequences and connection with ZP hardening are unknown. Biochemical and structural studies show that cleavage of ZP2 triggers its oligomerization. Moreover, the structure of a native vertebrate egg coat filament, combined with AlphaFold predictions of human ZP polymers, reveals that two protofilaments consisting of type I (ZP3) and type II (ZP1/ZP2/ZP4) components interlock into a left-handed double helix from which the NTRs of type II subunits protrude. Together, these data suggest that oligomerization of cleaved ZP2 NTRs extensively cross-links ZP filaments, rigidifying the egg coat and making it physically impenetrable to sperm.
Topics: Humans; Male; Semen; Spermatozoa; Zona Pellucida; Zona Pellucida Glycoproteins; Ovum; Female
PubMed: 38490181
DOI: 10.1016/j.cell.2024.02.013 -
Poultry Science Jan 2022Indigenous chickens (IC) contribute socioeconomically to household food security in the region of East Africa. However, their potential and improvement are not well... (Review)
Review
Indigenous chickens (IC) contribute socioeconomically to household food security in the region of East Africa. However, their potential and improvement are not well documented. This review is aimed at exploring the production and potential of indigenous chickens in East Africa. The various tools for literature search such as google search and Google scholars, agricultural journals, animal sciences and health journals, poultry related journals, and country online databases were used to gather information. IC were primarily reared by women and were kept predominantly under scavenging systems where the conditions of management (feeding, housing, and health care) are poor. They presented a high variation in their reproduction and production characteristics. The products (meat and eggs) were of good quality and preferred by the local consumers. Despite the variation and potential of IC, improvements in the village system were constrained by diseases and loss due to Newcastle, Gumboro, and Ecto-endo parasites and predators. Farmers primarily used traditional methods to control the diseases, and some used conventional medications and vaccines. Due to the potential of IC, the exploration of various strategies for improvement supported by the details of their genetic variability and adaptation as well as different management conditions was a goal of this review.
Topics: Agriculture; Animals; Chickens; Meat; Ovum
PubMed: 34844110
DOI: 10.1016/j.psj.2021.101547 -
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 -
Science (New York, N.Y.) Dec 2023Meiotic recombination commences with hundreds of programmed DNA breaks; however, the degree to which they are accurately repaired remains poorly understood. We report...
Meiotic recombination commences with hundreds of programmed DNA breaks; however, the degree to which they are accurately repaired remains poorly understood. We report that meiotic break repair is eightfold more mutagenic for single-base substitutions than was previously understood, leading to de novo mutation in one in four sperm and one in 12 eggs. Its impact on indels and structural variants is even higher, with 100- to 1300-fold increases in rates per break. We uncovered new mutational signatures and footprints relative to break sites, which implicate unexpected biochemical processes and error-prone DNA repair mechanisms, including translesion synthesis and end joining in meiotic break repair. We provide evidence that these mechanisms drive mutagenesis in human germ lines and lead to disruption of hundreds of genes genome wide.
Topics: Humans; Male; DNA Breaks, Double-Stranded; DNA Repair; Genome, Human; Meiosis; Mutagenesis; Mutation; Ovum; Recombination, Genetic; Semen; Translesion DNA Synthesis; Female
PubMed: 38033082
DOI: 10.1126/science.adh2531 -
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 -
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 -
Philosophical Transactions of the Royal... Sep 2020Microorganisms are associated with the eggs of many animals. For some hosts, the egg serves as the ideal environment for the vertical transmission of beneficial... (Review)
Review
Microorganisms are associated with the eggs of many animals. For some hosts, the egg serves as the ideal environment for the vertical transmission of beneficial symbionts between generations, while some bacteria use the egg to parasitize their hosts. In a number of animal groups, egg microbiomes often perform other essential functions. The eggs of aquatic and some terrestrial animals are especially susceptible to fouling and disease since they are exposed to high densities of microorganisms. To overcome this challenge, some hosts form beneficial associations with microorganisms, directly incorporating microbes and/or microbial products on or in their eggs to inhibit pathogens and biofouling. Other functional roles for egg-associated microbiomes are hypothesized to involve oxygen and nutrient acquisition. Although some egg-associated microbiomes are correlated with increased host fitness and are essential for successful development, the mechanisms that lead to such outcomes are often not well understood. This review article will discuss different functions of egg microbiomes and how these associations have influenced the biology and evolution of animal hosts. This article is part of the theme issue 'The role of the microbiome in host evolution'.
Topics: Animals; Biological Evolution; Host Microbial Interactions; Invertebrates; Microbiota; Ovum; Symbiosis; Vertebrates
PubMed: 32772674
DOI: 10.1098/rstb.2019.0593 -
Poultry Science Aug 2021Eggshell color is an important shell quality trait that influences consumer preference. It is also of particular importance with respect to sexual signaling and the... (Review)
Review
Eggshell color is an important shell quality trait that influences consumer preference. It is also of particular importance with respect to sexual signaling and the physiological and mechanical properties of shell pigment. Pigments include protoporphyrin IX, biliverdin, and traces of biliverdin zinc chelates, with brown eggs being notably rich in protoporphyrin IX, the synthesis of which has a marked effect on the intensity of brown eggshell color. This pigment is initially synthesized in the eggshell gland within the oviduct of laying hens and is subsequently deposited throughout the cuticular and calcareous layers of brown eggshell. In this review, we describe the factors affecting brown eggshell color and potential targets for the regulation of pigment synthesis. Protoporphyrin IX synthesis might be compromised by synthetase-mediated pigment synthesis, the redox status of the female birds, and regulation of the nuclear transcription factors associated with δ-aminolevulinic acid synthetase1. We believe that this review will provide a valuable reference for those engaged in studying eggshell depigmentation.
Topics: Animals; Biliverdine; Chickens; Egg Shell; Female; Ovum; Pigmentation
PubMed: 34214744
DOI: 10.1016/j.psj.2021.101273 -
Medecine Sciences : M/S 2023The Zona Pellucida (ZP) is an ovarian specialized extracellular coat surrounding the oocyte. In human, ZP is composed of four glycoproteins: ZP1, ZP2, ZP3 and ZP4. It... (Review)
Review
The Zona Pellucida (ZP) is an ovarian specialized extracellular coat surrounding the oocyte. In human, ZP is composed of four glycoproteins: ZP1, ZP2, ZP3 and ZP4. It regulates sperm binding to the oocyte during fertilization. After fertilization, ZP prevents polyspermia and is important for the protection of the developing embryo and oviductal transport avoiding ectopic implantation. According to the development of sequencing techniques, many mutations have been described in infertile patients. The aim of this review is to synthesize mutations in genes encoding ZP glycoproteins described in humans and their effects on female fertility.
Topics: Male; Humans; Female; Zona Pellucida; Semen; Oocytes; Embryo, Mammalian; Mutation
PubMed: 37387660
DOI: 10.1051/medsci/2023081 -
Annual Review of Entomology Jan 2023Insect eggs are exposed to a plethora of abiotic and biotic threats. Their survival depends on both an innate developmental program and genetically determined protective... (Review)
Review
Insect eggs are exposed to a plethora of abiotic and biotic threats. Their survival depends on both an innate developmental program and genetically determined protective traits provided by the parents. In addition, there is increasing evidence that () parents adjust the egg phenotype to the actual needs, () eggs themselves respond to environmental challenges, and () egg-associated microbes actively shape the egg phenotype. This review focuses on the phenotypic plasticity of insect eggs and their capability to adjust themselves to their environment. We outline the ways in which the interaction between egg and environment is two-way, with the environment shaping the egg phenotype but also with insect eggs affecting their environment. Specifically, insect eggs affect plant defenses, host biology (in the case of parasitoid eggs), and insect oviposition behavior. We aim to emphasize that the insect egg, although it is a sessile life stage, actively responds to and interacts with its environment.
Topics: Female; Animals; Insecta; Adaptation, Physiological; Oviposition; Plants; Phenotype; Ovum
PubMed: 36266253
DOI: 10.1146/annurev-ento-120120-100746