Sperm Activation Factor In Sea Urchin Egg
Sperm Activation Factor In Sea Urchin Egg
The interaction of sperm and egg generally proceeds according to five basic steps (Figure 7.8; Vacquier 1998):Figure 7.8Summary of events leading to the fusion of egg and sperm plasma membranes in the sea urchin (A) and the mouse (B). (A) Sea urchin fertilization is external. (1) The sperm is activated by and chemotactically attracted to the egg. (2, 3) The egg jelly causes the acrosomal ...
This chapter discusses the fertilization of the sea urchin egg. The metabolic and morphological changes of sea urchin gametes during fertilization are the best characterized of all embryos. In organization, this chapter explains the activation of both gametes, first considering the activation of the sperm upon its contact with egg jelly and the resultant cascade of the events leading to sperm ...
Does the sperm deliver an activating factor? sperm binding trigger a receptor-mediated signal? Or is the a complex combination? With the tools and knowledge gained from study of sea urchin fertilization, testing of these hypotheses feasible in the near future. Introduction tive experimental model system because
Since about 1880, the eggs and sperm of sea urchins have been used for the study of fertilization, the metabolic activation of development and gene regulatory mechanisms governing embryogenesis. Sea urchin gametes are a favorite material for observations of the process of fertilization in advanced high school, community college, and university biology laboratory courses. This article is a ...
We have a clear idea, then, of the basis and the importance of the fertilization calcium wave in sea urchin eggs. We are less certain about how the sperm detonates the calcium explosion, and we shall discuss here the pros and cons of two possible mechanisms, one involving a receptor - G protein interaction, the other the introduction of an activating cytoplasmic messenger when sperm and egg fuse.
The Fertilization Enigma Every new life begins with a microscopic dance—a sperm cell's race to fuse with an egg. In sea urchins, this process hinges on a explosive event called the acrosome reaction, where the sperm's tip undergoes dramatic changes to penetrate the egg's protective layers.
The first direct evidence for a soluble sperm factor came from studies that showed that injecting sperm extracts into sea urchin eggs could trigger the formation of the fertilization envelope (Dale et al. 1985).
The processes associated with fertilization help the egg and sperm get together, prevent the union of the sperm and egg of different species, and guarantee that only one sperm will enter and activate the egg metabolically. In the accompanying animation, we examine fertilization using an invertebrate animal—a sea urchin—as an example.
In sea urchins, acrosome-reacted sperm interact, presumably via the sperm protein bindin, with a highly glycosylated receptor on the egg surface. This article highlights the recent advances in the molecular structure of the sea urchin sperm receptor and discusses its possible role in egg activation.
The idea that the sperm contains some factor that activates the egg at fertilization can be traced back to Loeb's work in the early 20th century (Loeb 1913). He proposed that the sperm introduces a substance (a 'lysin') into sea urchin eggs to cause the formation of the fertilization envelope. He also proposed that there was a second factor that was essential for the egg to develop and ...
Introduction Sea urchin fertilization is a cornerstone model system for studying the intricate molecular dialogue between sperm and egg. A key aspect of this process is sperm chemotaxis, the directed swimming of sperm towards chemical cues released by the egg.
When sea urchin sperm encounter an egg with a positive charge, sperm-egg fusion is blocked. Thus, after the first sperm contacts the egg and causes the change, subsequent sperms are prevented from fusing.
Unfertilized sea urchin eggs are metabolically quiescent and arrested in interphase of the cell division cycle. Immediately after fertilization, metabolism and protein synthesis rates increase 20—fold and the cell division cycle resumes. The intracellular...
Several mechanisms are used to control the behaviour of sea urchin spermatozoa while fertilizing eggs. These include discrete regulatory steps that modulate the sperm activation sequence from spawning to gamete membrane fusion. After release from the testis, sperm motility is instantaneously activat …
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The general timing of events surrounding fertilization in the sea urchin is as follows. The sperm become activated and undergo the acrosome reaction, shooting out a long filament. The sperm then penetrates the jelly coat that surrounds the egg, and the plasma membranes fuse.
Here we provide an up-to-date discussion of the unique nature of sea urchin gametogenesis, including gonad structure, the dual gametogenic and somatic nutrient storage functions of sea urchin gonads, annual structural and molecular/genomic data and environmental control.
Thus, our results indicated that generation of massive Ca 2+ waves is neither indicative of sperm entry nor sufficient for cortical granules exocytosis in the inseminated sea urchin eggs, whereas the structure and functionality of the actin cytoskeleton are the major determining factors in the two processes.
Fertilization - Introduction Sea urchins have been a convenient system for studying fertilization and egg activation for a century. In fact, many of the key discoveries regarding species-specific sperm-egg binding and the signals that mediate the blocks to polypsermy and egg activation were made first in this system.
The sea urchin egg is surrounded by a gelatinous extracellular matrix called the jelly coat through which spermatozoa must pass before reaching the plasma membrane of the egg during fertilization (Fig.1). Lillie (1913) observed that the jelly coat, dissolved in sea...
gh carbon dioxide concentration. When dispersed in sea water the sperm become extremely motile ( eferred to as sperm activation). Once the sperm are activated their ability to participate to 180 micrometers in diameter. Lytechinus variegatus eggs are approxima
The sperm tail movement is a direct result from contributions of fluid mechanics, elasticity, and molecular-motor activity. Within the flagellum, the axonemal engine yields overall mechanical response and, ultimately, motility. This chapter attempts to provide a...
Here we provide an up-to-date discussion of the unique nature of sea urchin gametogenesis, including gonad structure, the dual gametogenic and somatic nutrient storage functions of sea urchin ...
The latent period of fertilization has been a term used in the sea urchin field to indicate the delay between the initial sperm-egg interaction and the initiation of the cortical reaction. The data on the timing of the latent period are not as extensive in any species outside the sea urchin.
The earliest perceivable response of echinoid eggs to the fertilizing sperm is a transient depolarization, the activation or fertilization potential (Steinhardt et al., 1971; Jaffe, 1976; Chambers and de Armendi, 1979). This change in electrical activity involves the...
These proteins then mediate the binding and subsequent events that lead to activation of the egg and delivery of the male genetic material. Because of these recent insights, the sea urchin egg is in a position to provide answers to one of the central debates in developmental biology—the mechanism of egg activation.
This review discusses identification, isolation and characterization of proteins mediating species-selective sperm-to-egg adhesion during sea urchin fertilization. Bindin is the only sea urchin sperm protein known to mediate species-selective sperm attachment to eggs.
simultaneously several of the events that occur within s gleWe find that thefertilization potential ( = 0)is followed sea urchin eggs at fertilization. The use ofsingle eggs allows by an increase in intracellular-free calcium beginning at23 _+ for the precise determination of the sequence ofevents which 3 s (n = 3)and the redox state ofthe pyridine nucleotides is unobtainable from studies that ...
The following points highlight the top seven events of fertilization in sea-urchin. The events are: 1. Contact and Recognition between Sperm and Egg 2. Acrosomal Reaction and Sperm Penetration 3. Binding of Sperm to the Egg 4. Prevention of Polyspermy 5. Metabolic Activation of the Egg 6. Formation of Pronuclei 7. Migration of Pronuclei and Fusion of the Genetic Material. Events of ...
A growing body of evidence from starfish and sea urchin eggs suggests that the prompt reorganization of the actin pools around the time of fertilization plays crucial regulatory roles not only in guiding sperm entry but also in modulating intracellular Ca 2+ signaling and egg activation.
Normal development Sperm, eggs, and fertilization Sea urchin and sand dollar gametes can be obtained in large numbers by intracoelomic injection of 0.5M KCl or by electrical stimulation; this leads to the shedding of gametes into sea water (in the case of eggs) or 'dry' into a dish (in the case of sperm).
To corroborate our earlier findings in starfish, we have tested how the early events of fertilization in sea urchin eggs are influenced by four different actin-binding drugs that promote either ...
ase of membrane conductance which leads to a depolarization of the egg's membrane potential. The positive-going activation potential of the sea urchin egg following attachment of the first sperm decreases the p
Following attachment of a sperm to the surface of a sea urchin egg clamped at a membrane potential (Vm) more positive than +17 mV, no changes in membrane conductance can be detected, the sperm does not enter the egg, and no morphological changes can be detected. At V m from +17 to −100 mV three characteristically different types of current profiles are observed: Type I are activation ...
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A growing body of evidence from starfish and sea urchin eggs suggests that the prompt reorganization of the actin pools around the time of fertilization plays crucial regulatory roles not only in guiding sperm entry but also in modulating intracellular Ca 2+ signaling and egg activation.
Sea urchin eggs are metabolically (biochemically) dormant and undergo an explosive meta-bolic activation after fusing with a sperm. Protein kinases play key roles in egg activation (Townley et al., 2009).
Multiple oyster spermatozoa can enter sea urchin eggs with or often without fertilization membrane formation (Osanai and Kyozuka, 1982). In the present work, electrical responses of sea urchin (Temnopleurus hardwicki) eggs inseminated with oyster (Crassostrea gigas) sperm were examined and correlated to the failure of monospermy and egg activation.
Evolutionarily, sea urchins are on the same lineage that led to mammals, and the size and shape of sea urchin eggs and sperm are similar to our own. Because they are easily studied, urchin eggs and sperm provide valuable information on fertilization and development that applies to many organisms, from jelly fish to humans.
Early studies on sea urchin fertilization, implicated a high molecular-weight glycoconjugate as an egg receptor for sperm. Characterization of a partially purified receptor preparation showed that the receptor bound to sperm and inhibited fertilization in a species-specific manner.
One is the fusion of the sperm acrosome granule membrane with the overlying sperm plasma membrane; the second is the massive exocytosis of egg cortical granules seconds after sperm-egg fusion (Epel and Vacquier, 1978). Finally, fertilization is also an excellent model for the study of the biochemical activation of two cells.
The spawning behavior of sea urchin species is variable and mass spawning events are rarely observed in nature [27]. Aggregation in sea urchin populations may be influenced by food availability or by reproductive behavior, both factors determining the fertilization rates and the outcome zygote production [59].
Scanning electron microscopy of the outer surface of sea urchin eggs sampled at intervals during the first 3 minutes after insemination reveals the detailed structural changes of the vitelline layer during its transformation into the fertilization ...
The sea urchin egg has a rich history of contributions to our understanding of fundamental questions of egg activation at fertilization. Within seconds of sperm-egg interaction, calcium is released from the egg endoplasmic reticulum, launching the zygote into the mitotic cell cycle and the developmental program.
Abstract Sperm interaction with an egg in animals was first documented 160 years ago in sea urchins by Alphonse Derbès (1847) when he noted the formation of an "envelope" following the sperm's "approach" to the egg.
In sea urchins, the sequence of the cellular and molecular events characterizing the fertilization process has been intensively studied. We have learned that to activate the egg, the fertilizing sperm must undergo morphological modifications (the acrosome reaction, AR) upon reaching the outer gelatinous layer enveloping the egg (egg jelly), which triggers the polymerization of F-actin on the ...
Four important events of fertilization in the sea urchin are: 1) the acrosome reaction of the sperm, 2) sperm-egg fusion, 3) the cortical reaction of the egg, and 4) the formation of the fertilization coat. The acrosome reaction is triggered by contact of the sperm with the jelly coat, a complex ext …
Methods for the isolation of different parts of the sea urchin sperm are discussed. Sea urchin sperm are specialized for five functions: (1) oxidative phosphorylation to produce ATP, (2) flagellar motility, (3) the acrosome reaction, (4) binding to the egg, and (5) fusion with the egg.
Image courtesy Gerald Schatten, Univ. of Pittsburgh. Sea urchins have been a convenient system for studying fertilization and egg activation for a century. In fact, many of the key discoveries regarding species-specific sperm-egg binding and the signals that mediate the blocks to polypsermy and egg activation were made first in this system.
In sea urchin, the immediate contact of the acrosome-reacted sperm with the egg surface triggers a series of structural and ionic changes in the egg cortex. Within one minute after sperm fuses with the egg plasma membrane, the cell membrane potential ...
One is the fusion ofthe sperm acrosome granule membrane with the overlying sperm plasma membrane; the second is the massive exocytosis of egg cortical granules seconds after sperm-egg fusion (Epel and Vacquier, 1978). Finally, fertilization is also an excellent model for the study of the biochemical activation of two cells.
Multiple oyster spermatozoa can enter sea urchin eggs with or often without fertilization membrane formation (Osanai and Kyozuka, 1982). In the present work, electrical responses of sea urchin (Temnopleurus hardwicki) eggs inseminated with oyster (Crassostrea gigas) sperm were examined and correlated to the failure of monospermy and egg activation.
The Sea Urchin in Research Many important discoveries in the areas of fertilization and early devel- opment resulted from experiments with sea urchin embryos. One such exciting discovery is the story of egg activation.
These proteins then mediate the binding and subsequent events that lead to activation of the egg and delivery of the male genetic material. Because of these recent insights, the sea urchin egg is in a position to provide answers to one of the central debates in developmental biology-the mechanism of egg activation.
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