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Arêdes DS, Rios T, Carvalho-Kelly LF, Braz V, Araripe LO, Bruno RV, Meyer-Fernandes JR, Ramos I, Gondim KC. Deficiency of Brummer lipase disturbs lipid mobilization and locomotion, and impairs reproduction due to defects in the eggshell ultrastructure in the insect vector Rhodnius prolixus. Biochim Biophys Acta Mol Cell Biol Lipids 2024; 1869:159442. [PMID: 38042331 DOI: 10.1016/j.bbalip.2023.159442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Revised: 11/27/2023] [Accepted: 11/29/2023] [Indexed: 12/04/2023]
Abstract
Rhodnius prolixus is a hematophagous insect, which feeds on large and infrequent blood meals, and is a vector of trypanosomatids that cause Chagas disease. After feeding, lipids derived from blood meal are stored in the fat body as triacylglycerol, which is recruited under conditions of energy demand by lipolysis, where the first step is catalyzed by the Brummer lipase (Bmm), whose orthologue in mammals is the adipose triglyceride lipase (ATGL). Here, we investigated the roles of Bmm in adult Rhodnius prolixus under starvation, and after feeding. Its gene (RhoprBmm) was expressed in all the analyzed insect organs, and its transcript levels in the fat body were not altered by nutritional status. RNAi-mediated knockdown of RhoprBmm caused triacylglycerol retention in the fat body during starvation, resulting in larger lipid droplets and lower ATP levels compared to control females. The silenced females showed decreased flight capacity and locomotor activity. When RhoprBmm knockdown occurred before the blood meal and the insects were fed, the females laid fewer eggs, which collapsed and showed low hatching rates. Their hemolymph had reduced diacylglycerol content and vitellogenin concentration. The chorion (eggshell) of their eggs had no difference in hydrocarbon amounts or in dityrosine crosslinking levels compared to control eggs. However, it showed ultrastructural defects. These results demonstrated that Bmm activity is important not only to guarantee lipid mobilization to maintain energy homeostasis during starvation, but also for the production of viable eggs after a blood meal, by somehow contributing to the right formation of the egg chorion.
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Affiliation(s)
- Daniela Saar Arêdes
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Thamara Rios
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | | | - Valdir Braz
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Luciana O Araripe
- Laboratório de Biologia Molecular de Insetos, Instituto Oswaldo Cruz, Rio de Janeiro, Brazil; Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular - INCT-EM/CNPq, Brazil
| | - Rafaela V Bruno
- Laboratório de Biologia Molecular de Insetos, Instituto Oswaldo Cruz, Rio de Janeiro, Brazil; Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular - INCT-EM/CNPq, Brazil
| | - José Roberto Meyer-Fernandes
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil; Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagem - INCT-BEB/CNPq, Brazil
| | - Isabela Ramos
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil; Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular - INCT-EM/CNPq, Brazil
| | - Katia C Gondim
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil; Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular - INCT-EM/CNPq, Brazil.
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2
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Berg C, Sieber M, Sun J. Finishing the egg. Genetics 2024; 226:iyad183. [PMID: 38000906 PMCID: PMC10763546 DOI: 10.1093/genetics/iyad183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Accepted: 09/27/2023] [Indexed: 11/26/2023] Open
Abstract
Gamete development is a fundamental process that is highly conserved from early eukaryotes to mammals. As germ cells develop, they must coordinate a dynamic series of cellular processes that support growth, cell specification, patterning, the loading of maternal factors (RNAs, proteins, and nutrients), differentiation of structures to enable fertilization and ensure embryonic survival, and other processes that make a functional oocyte. To achieve these goals, germ cells integrate a complex milieu of environmental and developmental signals to produce fertilizable eggs. Over the past 50 years, Drosophila oogenesis has risen to the forefront as a system to interrogate the sophisticated mechanisms that drive oocyte development. Studies in Drosophila have defined mechanisms in germ cells that control meiosis, protect genome integrity, facilitate mRNA trafficking, and support the maternal loading of nutrients. Work in this system has provided key insights into the mechanisms that establish egg chamber polarity and patterning as well as the mechanisms that drive ovulation and egg activation. Using the power of Drosophila genetics, the field has begun to define the molecular mechanisms that coordinate environmental stresses and nutrient availability with oocyte development. Importantly, the majority of these reproductive mechanisms are highly conserved throughout evolution, and many play critical roles in the development of somatic tissues as well. In this chapter, we summarize the recent progress in several key areas that impact egg chamber development and ovulation. First, we discuss the mechanisms that drive nutrient storage and trafficking during oocyte maturation and vitellogenesis. Second, we examine the processes that regulate follicle cell patterning and how that patterning impacts the construction of the egg shell and the establishment of embryonic polarity. Finally, we examine regulatory factors that control ovulation, egg activation, and successful fertilization.
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Affiliation(s)
- Celeste Berg
- Department of Genome Sciences, University of Washington, Seattle, WA 98195-5065USA
| | - Matthew Sieber
- Department of Physiology, UT Southwestern Medical Center, Dallas, TX 75390USA
| | - Jianjun Sun
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT 06269USA
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Urbán-Duarte D, Tomita S, Sakai H, Sezutsu H, De La Torre-Sánchez JF, Kainoh Y, Furukawa S, Uchino K. An Effective Chemical Permeabilization of Silkworm Embryos. Bioengineering (Basel) 2023; 10:bioengineering10050563. [PMID: 37237633 DOI: 10.3390/bioengineering10050563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 04/24/2023] [Accepted: 05/03/2023] [Indexed: 05/28/2023] Open
Abstract
The lipid layer surrounding the vitelline membrane of insect eggs has a critical role in the waterproofing and desiccation resistance of embryos. However, this lipid layer also prevents the flux of chemicals into the embryos, such as cryoprotectants, which are required for successful cryopreservation. The permeabilization studies of silkworm embryos remain insufficient. Therefore, in this study, we developed a permeabilization method to remove the lipid layer in the silkworm, Bombyx mori, and examined factors affecting the viability of dechorionated embryos, including the types and exposure times of chemicals and embryonic stages. Among the chemicals used, hexane and heptane were effective for permeabilization, whereas Triton X-100 and Tween-80 were less effective. Regarding the embryonic stages, there were significant differences between 160 and 166 h after egg laying (AEL) at 25 °C. Consequently, we found that the treatment of 160 AEL embryos with hexane for 30 s was the best condition for the permeability and viability of embryos, in which over 62% of the permeabilized embryos grew up to the second larval instar and their moths could lay fertilized eggs. Our method can be used for various purposes, including permeability investigations using other chemicals and embryonic cryopreservation.
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Affiliation(s)
- David Urbán-Duarte
- Centro Nacional de Recursos Genéticos, Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias, Tepatitlán de Morelos 47600, Jalisco, Mexico
| | - Shuichiro Tomita
- Institute of Agrobiological Sciences, National Agriculture and Food Research Organization, 1-2 Owashi, Tsukuba 305-8634, Ibaraki, Japan
| | - Hiroki Sakai
- Institute of Agrobiological Sciences, National Agriculture and Food Research Organization, 1-2 Owashi, Tsukuba 305-8634, Ibaraki, Japan
| | - Hideki Sezutsu
- Institute of Agrobiological Sciences, National Agriculture and Food Research Organization, 1-2 Owashi, Tsukuba 305-8634, Ibaraki, Japan
| | - José Fernando De La Torre-Sánchez
- Centro Nacional de Investigación Disciplinaria en Agricultura Familiar, Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias, Ojuelos 47540, Jalisco, Mexico
| | - Yooichi Kainoh
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tennodai 1-1-1, Tsukuba 305-8572, Ibaraki, Japan
| | - Seiichi Furukawa
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tennodai 1-1-1, Tsukuba 305-8572, Ibaraki, Japan
| | - Keiro Uchino
- Institute of Agrobiological Sciences, National Agriculture and Food Research Organization, 1-2 Owashi, Tsukuba 305-8634, Ibaraki, Japan
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Moraes B, Braz V, Santos-Araujo S, Oliveira IA, Bomfim L, Ramos I, Gondim KC. Deficiency of Acetyl-CoA Carboxylase Impairs Digestion, Lipid Synthesis, and Reproduction in the Kissing Bug Rhodnius prolixus. Front Physiol 2022; 13:934667. [PMID: 35936892 PMCID: PMC9353303 DOI: 10.3389/fphys.2022.934667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Accepted: 06/14/2022] [Indexed: 11/14/2022] Open
Abstract
Rhodnius prolixus is a hematophagous insect, vector of Chagas disease. After feeding, as blood is slowly digested, amino acids are used as substrates to fuel lipid synthesis, and adult females accumulate lipids in the fat body and produce eggs. In order to evaluate the importance of de novo fatty acid synthesis for this insect metabolism, we generated acetyl-CoA carboxylase (ACC) deficient insects. The knockdown (AccKD) females had delayed blood digestion and a shorter lifespan. Their fat bodies showed reduced de novo lipogenesis activity, did not accumulate triacylglycerol during the days after blood meal, and had smaller lipid droplets. At 10 days after feeding, there was a general decrease in the amounts of neutral lipids and phospholipids in the fat body. In the hemolymph, no difference was observed in lipid composition at 5 days after blood meal, but at day ten, there was an increase in hydrocarbon content and a decrease in phospholipids. Total protein concentration and amino acid composition were not affected. The AccKD females laid 60% fewer eggs than the control ones, and only 7% hatched (89% for control), although their total protein and triacylglycerol contents were not different. Scanning electron microscopy of the egg surface showed that chorion (eggshell) from the eggs laid by the AccKD insects had an altered ultrastructural pattern when compared to control ones. These results show that ACC has a central role in R. prolixus nutrient homeostasis, and its appropriate activity is important to digestion, lipid synthesis and storage, and reproductive success.
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Affiliation(s)
- Bruno Moraes
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Valdir Braz
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Samara Santos-Araujo
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Isadora A. Oliveira
- Centro de Espectrometria de Massas de Biomoléculas, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Larissa Bomfim
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Isabela Ramos
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Katia C. Gondim
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
- *Correspondence: Katia C. Gondim,
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Narasimha S, Nagornov KO, Menin L, Mucciolo A, Rohwedder A, Humbel BM, Stevens M, Thum AS, Tsybin YO, Vijendravarma RK. Drosophila melanogaster cloak their eggs with pheromones, which prevents cannibalism. PLoS Biol 2019; 17:e2006012. [PMID: 30629594 PMCID: PMC6328083 DOI: 10.1371/journal.pbio.2006012] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Accepted: 12/07/2018] [Indexed: 01/14/2023] Open
Abstract
Oviparous animals across many taxa have evolved diverse strategies that deter egg predation, providing valuable tests of how natural selection mitigates direct fitness loss. Communal egg laying in nonsocial species minimizes egg predation. However, in cannibalistic species, this very behavior facilitates egg predation by conspecifics (cannibalism). Similarly, toxins and aposematic signaling that deter egg predators are often inefficient against resistant conspecifics. Egg cannibalism can be adaptive, wherein cannibals may benefit through reduced competition and added nutrition, but since it reduces Darwinian fitness, the evolution of anticannibalistic strategies is rife. However, such strategies are likely to be nontoxic because deploying toxins against related individuals would reduce inclusive fitness. Here, we report how D. melanogaster use specific hydrocarbons to chemically mask their eggs from cannibal larvae. Using an integrative approach combining behavioral, sensory, and mass spectrometry methods, we demonstrate that maternally provisioned pheromone 7,11-heptacosadiene (7,11-HD) in the eggshell’s wax layer deters egg cannibalism. Furthermore, we show that 7,11-HD is nontoxic, can mask underlying substrates (for example, yeast) when coated upon them, and its detection requires pickpocket 23 (ppk23) gene function. Finally, using light and electron microscopy, we demonstrate how maternal pheromones leak-proof the egg, consequently concealing it from conspecific larvae. Our data suggest that semiochemicals possibly subserve in deceptive functions across taxa, especially when predators rely on chemical cues to forage, and stimulate further research on deceptive strategies mediated through nonvisual sensory modules. This study thus highlights how integrative approaches can illuminate our understanding on the adaptive significance of deceptive defenses and the mechanisms through which they operate. Egg-laying species that lack parental care often protect their eggs from predators by laying them in communal groups or by fortifying them with toxins. However, these strategies may backfire when the predators are from the same species (cannibals) since a) there are plenty of available eggs in these sites, b) the cannibals may be resistant to the toxins, and c) poisoning cannibals who may be related would reduce inclusive fitness. Under these circumstances, natural selection should favor anticannibalistic strategies that are likely to be nontoxic. Here, we investigate how fruit flies (Drosophila melanogaster), which oviposit communally, protect their eggs from cannibalism by their own larvae. We show that maternal hydrocarbons incorporated into the egg’s wax layer to make them waterproof interestingly also serve as a mask that conceals their identity from cannibal larvae. In particular, we identify one female sex pheromone that deters cannibalism by forming a layer around the egg to conceal it. We further demonstrate that this pheromone is nontoxic and can mask underlying substrates such as yeast when used as a coating. While deceptive strategies (such as camouflage) deployed to avoid predation are extensively studied from a visual perspective, our findings suggest that deceptive strategies operating through other nonvisual sensory systems might be equally common across taxa.
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Affiliation(s)
- Sunitha Narasimha
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
| | | | - Laure Menin
- Institute of Chemical Sciences and Engineering, EPFL, Lausanne, Switzerland
| | - Antonio Mucciolo
- Electron Microscopy Facility, University of Lausanne, Lausanne, Switzerland
| | - Astrid Rohwedder
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - Bruno M. Humbel
- Electron Microscopy Facility, University of Lausanne, Lausanne, Switzerland
| | - Martin Stevens
- Centre for Ecology & Conservation, University of Exeter, United Kingdom
| | - Andreas S. Thum
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - Yury O. Tsybin
- Spectroswiss Sàrl, EPFL Innovation Park, Lausanne, Switzerland
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6
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Dias FA, Gandara ACP, Queiroz-Barros FG, Oliveira RLL, Sorgine MHF, Braz GRC, Oliveira PL. Ovarian dual oxidase (Duox) activity is essential for insect eggshell hardening and waterproofing. J Biol Chem 2013; 288:35058-67. [PMID: 24174530 DOI: 10.1074/jbc.m113.522201] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In insects, eggshell hardening involves cross-linking of chorion proteins via their tyrosine residues. This process is catalyzed by peroxidases at the expense of H2O2 and confers physical and biological protection to the developing embryo. Here, working with Rhodnius prolixus, the insect vector of Chagas disease, we show that an ovary dual oxidase (Duox), a NADPH oxidase, is the source of the H2O2 that supports dityrosine-mediated protein cross-linking and eggshell hardening. RNAi silencing of Duox activity decreased H2O2 generation followed by a failure in embryo development caused by a reduced resistance to water loss, which, in turn, caused embryos to dry out following oviposition. Phenotypes of Duox-silenced eggs were reversed by incubation in a water-saturated atmosphere, simultaneous silencing of the Duox and catalase genes, or H2O2 injection into the female hemocoel. Taken together, our results show that Duox-generated H2O2 fuels egg chorion hardening and that this process plays an essential role during eggshell waterproofing.
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Affiliation(s)
- Felipe A Dias
- From the Instituto de Bioquímica Médica Leopoldo De Meis, Programa de Biologia Molecular e Biotecnología, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-590
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7
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Abstract
The molecular mechanisms controlling Drosophila embryogenesis are among the best-studied examples in animal development. Whereas the formation of developmental pattern in embryos was intensely examined in the past three decades, the cell biological basis of morphogenesis is now entering the center stage of the research on fly embryos. A fundamentally important procedure has always been to determine the subcellular localization of proteins in embryos by immunolabeling. The challenge of the commonly used whole mount-staining procedures is to balance a good structural preservation during fixation and allow at the same time the penetration of the antibodies through the tissue. Different procedures have been developed that allow the preservation of distinct compartments of the cell and thus, optimize for the specific subcellular localization of proteins. This chapter provides a general immunolabeling protocol with variations suitable for a broad panel of antigens.
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Affiliation(s)
- H-Arno J Müller
- Division of Cell and Developmental Biology, College of Life Sciences, University of Dundee, Scotland UK
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8
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Papassideri IS, Trougakos IP, Leonard KR, Margaritis LH. Crystalline yolk spheroids in Drosophila melanogaster oocyte: freeze fracture and two-dimensional reconstruction analysis. JOURNAL OF INSECT PHYSIOLOGY 2007; 53:370-6. [PMID: 17292389 DOI: 10.1016/j.jinsphys.2006.12.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2006] [Revised: 10/26/2006] [Accepted: 12/21/2006] [Indexed: 05/13/2023]
Abstract
The major sites of energy storage during oogenesis in the Drosophila melanogaster oocyte are the alpha- and beta-yolk spheres. By applying biochemical and transmission electron microscopy (TEM) immunogold techniques we found that the beta-yolk spheres contain mainly polysaccharides, while the three main yolk proteins (YPs) are stored in the alpha-yolk spheres of the developing oocyte. Moreover, by using high-resolution TEM of freeze fractured or cryosectioned follicles, we identified the existence of crystalline structures within the alpha-yolk spheres of the mature oocyte. Our subsequent two-dimensional reconstruction analysis revealed that the unit cell of the crystal is about 113 Angstrom x 113 Angstrom. Assuming that the repeating unit is a cylinder of about 110 Angstrom in length and 25 Angstrom in diameter this cylinder would then have a volume of about 50,000 cubic Angstrom, which corresponds to about 40 kDa of protein. This size fits quite well with the known molecular weight of about 40-45 kDa for each of the three D. melanogaster YPs. Overall, our study identifies for the first time the supramolecular arrangement of the alpha-yolk spheres constituent molecules and provides direct evidence for the "natural" crystallization, and therefore the efficient packaging, of the YPs during oogenesis.
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Affiliation(s)
- Issidora S Papassideri
- Department of Cell Biology and Biophysics, Athens University, Panepistimiopolis, Zografou, Athens 15784, Greece.
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9
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Abstract
Drosophila melanogaster mature oocytes in ovaries are arrested at metaphase I of meiosis. Eggs that have reached the uterus have released this arrest. It was not known where in the female reproductive tract egg activation occurs and what triggers it. We investigated when and where the egg is activated in Drosophila in vivo and at what meiotic stage the egg is fertilized. We found that changes in the egg's envelope's permeability, one feature of activation, initiate during ovulation, even while most of the egg is still within the ovary. The egg becomes impermeable as it proceeds down the oviducts; the process is complete by the time the egg is in the uterus. Cross-linking of vitelline membrane protein sV23 also increases progressively as the egg moves through the oviducts and the uterus. Activation also triggers meiosis to resume before the egg reaches the uterus, such that the earliest eggs that reach the uterus are in anaphase I. We discuss models for Drosophila egg activation in vivo.
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Affiliation(s)
- Y Heifetz
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853-2703, USA
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10
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Wang WB, Leopold RA, Nelson DR, Freeman TP. Cryopreservation of Musca domestica (Diptera: Muscidae) embryos. Cryobiology 2000; 41:153-66. [PMID: 11034794 DOI: 10.1006/cryo.2000.2278] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Prior studies on cryopreserving embryos of several non-drosophilid flies established that two Drosophila melanogaster embryo cryopreservation protocols were not directly suitable for use with these species. This paper describes our work on developing a protocol for cryopreservation of embryos of the housefly, Musca domestica. Significant progress was made when permeabilization of the vitelline membrane was optimized, a vitrification solution containing ethylene glycol, polyethylene glycol, and trehalose was formulated, and when cooling and recovery of the cryopreservation protocol included a step which passed the embryos through liquid nitrogen vapor. More than 70% of housefly embryos withstand treatments of dechorionation, permeabilization, loading with cryoprotectant, and dehydration in vitrification solution, but the cooling, warming, and poststorage rearing steps still cause a considerable reduction in survival. About 53% of the vitrified M. domestica embryos hatched into larvae. Relative to the percentage of the control adult emergence, about 13% of the embryos stored in liquid nitrogen developed into fertile adults. Hatching of the F(1) progeny of adults having been cryopreserved as embryos was similar to control levels.
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Affiliation(s)
- W B Wang
- Department of Plant Pathology, North Dakota State University, Fargo, North Dakota 58105, USA.
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11
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Abstract
The Drosophila eggshell is a specialized extracellular matrix that forms between the oocyte and overlaying somatic follicle cells during the latter stages of oogenesis. Largely proteinaceous, the eggshell is a highly organized multilayered structure with regional specializations designed to perform a variety of functions. Production of a functional eggshell features: (1) the differentiation of subsets of follicle cells in response to ovarian signals, (2) directed migrations of the follicle cells within the developing egg chamber, (3) expression of eggshell structural genes by the follicle cells in a defined temporal and spatial order, (4) postdepositional modifications of the eggshell proteins including several temporally regulated proteolytic cleavage events, and (5) regulated trafficking of several eggshell proteins in the assembling structure. By exploiting the genetic advantages of Drosophila and using evolution as a guide, the eggshell provides an excellent experimental system to study, in vivo, molecular mechanisms used to regulate protein-protein interactions throughout the assembly of a complex extracellular architecture in a developing organism.
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Affiliation(s)
- G L Waring
- Department of Biology, Marquette University, Milwaukee, WI 53201-1881, USA
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12
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Papassideri IS, Margaritis LH. The eggshell of Drosophila melanogaster: IX. Synthesis and morphogenesis of the innermost chorionic layer. Tissue Cell 1996; 28:401-9. [PMID: 8760855 DOI: 10.1016/s0040-8166(96)80026-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Synthesis and morphogenesis of the innermost chorionic layer (ICL) was investigated by conventional EM methods, freeze-fracturing, tissue culture in Robb's medium, and EM autoradiography. Both autoradiography and fine structure results have shown that ICL-components are secreted prior to other chorion proteins. Their secretion starts on stage 12a but the first layer of ICL molecules is visible at stage 12b. Its thickness is gradually increased during the next stages, taking first, a bilaminar form along with the inner endochorion. Later, at the end of choriogenesis, ICL is detached from the endochorion and takes its final thickness and configuration, consisting of a 3-dimensional crystal, about 40 nm thick. The isolated ICL in conditions of air water interface is a monolayer crystal 10 nm thick. Studies on chorion mutants showed that the amount of protein secreted by the follicle cells is independent to the process of crystallisation. These data show how a proteinaceous extracellular substance is gradually assembled to form a 3-D crystal and how it can be organised to perform functions such as the physiological resistance of the insect eggs against water loss or water uptake, whenever they are laid on substrates with extreme environmental conditions. These functions are performed by ICL in conjunction with the underlying wax layer.
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Affiliation(s)
- I S Papassideri
- Department of Biology, University of Athens, Panepistimiopolis, Greece.
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