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Current Topics in Developmental Biology 2018All fish eggs are surrounded by an envelope, called the zona pellucida (ZP), that plays various roles during oogenesis, egg deposition, fertilization, and embryogenesis.... (Review)
Review
All fish eggs are surrounded by an envelope, called the zona pellucida (ZP), that plays various roles during oogenesis, egg deposition, fertilization, and embryogenesis. The fish egg ZP consists of only a few proteins that are homologs of mammalian ZP proteins ZP1, ZP3, and ZP4. Unlike the situation in mammals, in fishes there are often multiple copies of ZP genes, perhaps a consequence of ancient polyploidization, gene amplification, and mutation. Like mammalian ZP proteins, fish egg ZP1-like proteins exhibit conserved organization with distinct domains and motifs, but unlike mammalian ZP1 and ZP4 have a glutamine (Q)- and/or proline (P)-rich stretch as an N-terminal extension. Such extensions may play a role in assembly of ZP fibrils and/or account for certain properties of the fish egg ZP, such as elasticity. Recent proposals suggest that fish egg ZP proteins can adopt amyloid-like structures, serve as antifreeze proteins in Antarctic icefishes, and protect eggs subjected to desiccating conditions in small shallow pools. In this chapter, these and other aspects of fish egg ZP proteins are presented.
Topics: Animals; Egg Proteins; Female; Fishes; Oogenesis; Ovum; Zona Pellucida
PubMed: 29853180
DOI: 10.1016/bs.ctdb.2018.01.002 -
Current Topics in Developmental Biology 2018All mammalian eggs are surrounded by a highly specialized extracellular matrix (ECM), called the zona pellucida (ZP), that functions before, during, and after... (Review)
Review
All mammalian eggs are surrounded by a highly specialized extracellular matrix (ECM), called the zona pellucida (ZP), that functions before, during, and after fertilization. Unlike somatic cell ECM the mouse ZP is composed of three different proteins, ZP1-3, that are synthesized and secreted by growing oocytes and assembled into long interconnected fibrils. ECM or vitelline envelope (VE) that surrounds fish, reptilian, amphibian, and avian eggs also consists of a limited number of proteins all closely related to ZP1-3. Messenger RNAs encoding ZP1-3 are expressed only by growing oocytes at very high levels from single-copy genes present on different chromosomes. Processing at the amino- and carboxy-termini of nascent ZP1-3 permits secretion of mature proteins into the extracellular space and assembly into fibrils and matrix. Structural features of nascent ZP proteins prevent assembly within secretory vesicles of growing oocytes. Homozygous knockout female mice that fail to synthesize either ZP2 or ZP3 are unable to construct a ZP, ovulate few if any eggs, and are infertile. ZP1-3 have a common structural feature, the ZP domain (ZPD), that has been conserved through 600 million years of evolution and is essential for ZP protein assembly into fibrils. The ZPD consists of two subdomains, each with four conserved cysteine residues present as two intramolecular disulfides, and resembles an immunoglobulin (Ig) domain found in a wide variety of proteins that have diverse functions, from receptors to mechanical transducers. ZP2 and ZP3 function as receptors for acrosome-reacted and acrosome-intact sperm, respectively, during fertilization of ovulated eggs, but are inactivated as sperm receptors as a result of fertilization.
Topics: Animals; Female; Fertilization; Mice; Ovum; Protein Domains; Protein Multimerization; Sperm-Ovum Interactions; Zona Pellucida; Zona Pellucida Glycoproteins
PubMed: 29853182
DOI: 10.1016/bs.ctdb.2018.01.003 -
Current Topics in Developmental Biology 2018Mammals evolved from oviparous reptiles that laid eggs in a dry, terrestrial environment, thus requiring large amounts of yolk to support development and tough, outer... (Review)
Review
Mammals evolved from oviparous reptiles that laid eggs in a dry, terrestrial environment, thus requiring large amounts of yolk to support development and tough, outer coats to protect them. Eutherian mammals such as humans and mice exhibit an "extreme" form of viviparity in which yolk and conceptus coats have become largely redundant. However, the "other" mammals-monotremes and marsupials-have retained and modified some features of reptilian development that provide valuable insights into the evolution of viviparity in mammals. Most striking of these are the conceptus coats, which include the zona pellucida, the mucoid coat, and the shell coat. We discuss current knowledge of these coats in monotremes and marsupials, their possible roles, and recently identified components such as the zona pellucida protein ZPAX, conceptus coat mucin (CCM), and nephronectin (NPNT).
Topics: Animals; Egg Proteins; Embryo, Mammalian; Marsupialia; Monotremata; Ovum; Zona Pellucida; Zona Pellucida Glycoproteins; Zygote
PubMed: 29853183
DOI: 10.1016/bs.ctdb.2018.03.004 -
Annual Review of Genetics Nov 2017Sexual reproduction crucially depends on the production of sperm in males and oocytes in females. Both types of gamete arise from the same precursor, the germ cells. We... (Review)
Review
Sexual reproduction crucially depends on the production of sperm in males and oocytes in females. Both types of gamete arise from the same precursor, the germ cells. We review the events that characterize the development of germ cells during fetal life as they commit to, and prepare for, oogenesis or spermatogenesis. In females, fetal germ cells enter meiosis, whereas in males they delay meiosis and instead lose pluripotency, activate an irreversible program of prospermatogonial differentiation, and temporarily cease dividing. Both pathways involve sex-specific molecular signals from the somatic cells of the developing gonads and a suite of intrinsic receptors, signal transducers, transcription factors, RNA stability factors, and epigenetic modulators that act in complex, interconnected positive and negative regulatory networks. Understanding these networks is important in the contexts of the etiology, diagnosis, and treatment of infertility and gonadal cancers, and in efforts to augment human and animal fertility using stem cell approaches.
Topics: Animals; Female; Gene Expression Regulation, Developmental; Gene Regulatory Networks; Humans; Infertility, Female; Infertility, Male; Male; Meiosis; Oocytes; Oogenesis; Ovum; Sex Determination Processes; Sex Differentiation; Signal Transduction; Spermatogenesis; Spermatozoa
PubMed: 28853925
DOI: 10.1146/annurev-genet-120215-035449 -
Biochemical and Biophysical Research... Aug 2014A description and update of the "egg-as-novelty" hypothesis is presented. It is proposed that the major animal phylum-characteristic suites of morphological motifs first... (Review)
Review
A description and update of the "egg-as-novelty" hypothesis is presented. It is proposed that the major animal phylum-characteristic suites of morphological motifs first emerged more than a half-billion years ago in multicellular aggregates and clusters that did not exhibit an egg-soma divergence. These pre-metazoan bodies were organized by "dynamical patterning modules" (DPMs), physical processes and effects mobilized on the new multicellular scale by ancient conserved genes that came to mediate cell-cell interactions in these clusters. "Proto-eggs" were enlarged cells that through cleavage, or physical confinement by a secreted matrix, served to enforce genomic and genetic homogeneity in the cell clusters arising from them. Enlargement of the founder cell was the occasion for spontaneous intra-egg spatiotemporal organization based on single-cell physiological functions - calcium transients and oscillations, cytoplasmic flows - operating on the larger scale. Ooplasmic segregation by egg-patterning processes, while therefore not due to adaptive responses to external challenges, served as evolutionarily fertile "pre-adaptations" by making the implementation of the later-acting (at the multicellular "morphogenetic stage" of embryogenesis) DPMs more reliable, robust, and defining of sub-phylum morphotypes. This perspective is seen to account for a number of otherwise difficult to understand features of the evolution of development, such as the rapid diversification of biological forms with a conserved genetic toolkit at the dawn of animal evolution, the capability of even obligatory sexual reproducers to propagate vegetatively, and the "embryonic hourglass" of comparative developmental biology.
Topics: Animals; Biological Evolution; Body Patterning; Chimera; Embryonic Development; Female; Fertilization; Growth and Development; Male; Models, Biological; Ovum; Species Specificity
PubMed: 24704442
DOI: 10.1016/j.bbrc.2014.03.132 -
Trends in Ecology & Evolution May 2023When biological material is transferred from one individual's body to another, as in ejaculate, eggs, and milk, secondary donor-produced molecules are often transferred... (Review)
Review
When biological material is transferred from one individual's body to another, as in ejaculate, eggs, and milk, secondary donor-produced molecules are often transferred along with the main cargo, and influence the physiology and fitness of the receiver. Both social and solitary animals exhibit such social transfers at certain life stages. The secondary, bioactive, and transfer-supporting components in socially transferred materials have evolved convergently to the point where they are used in applications across taxa and type of transfer. The composition of these materials is typically highly dynamic and context dependent, and their components drive the physiological and behavioral evolution of many taxa. Our establishment of the concept of socially transferred materials unifies this multidisciplinary topic and will benefit both theory and applications.
Topics: Animals; Sexual Behavior, Animal; Milk; Ovum; Semen
PubMed: 36543692
DOI: 10.1016/j.tree.2022.11.010 -
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 -
Poultry Science Oct 2017Eggs and egg products form an integral part of the food chain. As such, research into egg structure, function, and production has made an important contribution to the... (Review)
Review
Eggs and egg products form an integral part of the food chain. As such, research into egg structure, function, and production has made an important contribution to the field of poultry science. The past decade has seen significant advances in avian egg science research, with work supplementing our understanding of the nature of the avian egg, and its biological, chemical, and physical properties. Eggshell color, strength, and chemical composition, poultry nutrition, and genetics have all been intensively studied recently, with significant progress being made in a number of these areas. Indeed, with the prevalence of robust theoretical techniques, it is now commonplace to combine experimental investigations with theory, providing a balanced and interdisciplinary perspective.
Topics: Animal Husbandry; Animals; Chickens; Eggs; Ovum; Poultry
PubMed: 28938769
DOI: 10.3382/ps/pex187 -
Seminars in Cell & Developmental Biology Feb 2017Twenty-seven serpins belonging to clade A, B, C, D, E, F, G, H and I serpins are currently referenced in chicken genome databases. Phylogenetic analysis of chicken... (Review)
Review
Twenty-seven serpins belonging to clade A, B, C, D, E, F, G, H and I serpins are currently referenced in chicken genome databases. Phylogenetic analysis of chicken serpins revealed that ovalbumin (Serpinb14) and its paralogs ovalbumin-related protein Y (Serpinb14b) and ovalbumin-related protein X (Serpinb14c) are found in bird species. These clade B serpins are specifically expressed in reproductive tissues and exported in the egg where they constitute major protein components. These data suggest that these three paralogs have probably appeared in birds to face new environments and ensure the extra-uterine development of an embryo in a shell egg. Twelve other serpins have been identified in the newly produced egg, some of them having a specific distribution in the respective egg structures (eggshell, egg white, vitelline membrane and egg yolk). The physiological role of these egg serpins remain largely unexplored, but there is increasing evidence in literature or by homologies with their mammalian counterparts, that some of them participate in cell proliferation, tissue remodeling and/or angiogenesis associated with folliculogenesis and development of extraembryonic structures, eggshell biomineralization, egg defense and nutrition of the embryo. A better knowledge of the phylogenetic evolution of these 15 serpins in other oviparous species, on their egg distribution, on their regulation during embryonic development (activation/degradation/transfer) and on their functional specificity, is needed to better appreciate their role and their bird-specificity. These review shed light on the multiple possibilities that offer the avian egg model to study the role of serpins in reproduction and developmental biology.
Topics: Animals; Chickens; Evolution, Molecular; Models, Molecular; Ovum; Phylogeny; Serpins
PubMed: 27565683
DOI: 10.1016/j.semcdb.2016.08.019 -
Trends in Cell Biology Jan 2017Eggs and sperm develop through a specialized cell division called meiosis. During meiosis, the number of chromosomes is reduced by two sequential divisions in... (Review)
Review
Eggs and sperm develop through a specialized cell division called meiosis. During meiosis, the number of chromosomes is reduced by two sequential divisions in preparation for fertilization. In human female meiosis, chromosomes frequently segregate incorrectly, resulting in eggs with an abnormal number of chromosomes. When fertilized, these eggs give rise to aneuploid embryos that usually fail to develop. As women become older, errors in meiosis occur more frequently, resulting in increased risks of infertility, miscarriage, and congenital syndromes, such as Down's syndrome. Here, we review recent studies that identify the mechanisms causing aneuploidy in female meiosis, with a particular emphasis on studies in humans.
Topics: Aging; Aneuploidy; Humans; Meiosis; Models, Biological; Ovum; Spindle Apparatus
PubMed: 27773484
DOI: 10.1016/j.tcb.2016.09.002