Egg Water Research Articles

Microclimate of ostrich nests: measurements of egg temperature and nest humidity using egg hygrometers

1. A method is described for determining the temperature of fertile and infertile eggs of the African Ostrich, the absolute humidity of the nest and ambient air during 41 days of incubation without recourse to direct thermometry or relative humidity sensor. These values are calculated from weekly determinations of mass changes of a diffusion hygrometer made from an ostrich eggshell, and eggs in the nest, some of whose shell conductance to water vapor had been previously established. 2. During the incubation period the absolute nest humidity remained relatively constant at a mean value of 13.2 Torr and is maintained 4.7 Torr above the ambient humidity. The saturation water vapor pressure of fertile (but not of infertile) eggs gradually increases from 41 to 47 Torr because of the rise in egg temperature from 34.5 to 37.1°C at the end of incubation. Infertile eggs remain at 35.0°C. 3. Because of the increase in saturation vapor pressure of fertile eggs during the last half of incubation, the water vapor pressure difference between the egg and the nest air increases. This change accounts for the proportional change in egg water loss which increases from 4.3 to 5.0 g d−1 at the end of 41 days.

Cytological Characterization of Self Incompatibility in Gametes of the Ascidian, Ciona intestinalis: (Ciona gametes/self incompatibility/egg water/sperm-vitelline coat interaction/DAPI staining).

We have determined how many elements are involved in the regulation of self-fertilization in the solitary ascidian, Ciona intestinalis that is an incompletely self-sterile species. Animals collected in the field were repeatedly induced to spawn in order to examine their selfing ratios. About 20% of them were self-fertile, although the ratios fluctuated considerably among respective spawnings. Naturally or acid-induced self-fertile gametes required much longer time for selfing than that for crossing. Egg-suspending seawater (egg water) as such activated sperm motility, but it lowered conspicuously the self-fertilization ratio. Self-sterile spermatozoa could scarcely bind to the vitelline coat (VC) of glycerinated autologous eggs. or in case they bound well to it the sperm flagella ceased to beat within five min of the 'insemination'. The staining of sectioned gametes with DAPI, a fluorescent dye of DNA, showed that in selfing the spermatozoa could hardly penetrate the VC even though they bound well to it. The results of this study show that the block of self-fertilization can be classified into four elements from a phenomenal viewpoint, such as egg water, low affinity of sperm-VC binding, inactivation of bound sperm and difficulty in sperm penetration through the VC.

Water Balance in Incubating Turkey Eggs

The eggshell water vapor conductance capable of maintaining constant water content in incubating turkey eggs was determined for three different egg weight classifications. Metabolism of the developing turkey embryos was altered by increasing or decreasing eggshell permeability. Eggshell permeability accommodated metabolic water in large eggs very well. Both relative poult weights and relative water content of embryos in large eggs at the plateau stage in oxygen consumption decreased or increased allometrically to the permeability treatment. However, among small and medium eggs, if eggshell permeability was increased, relative poult weights at hatching were much less than expected. This occurred despite the fact that relative water content of the eggs at 25 days of incubation was not similarly affected. The data suggest a biological asynchrony for egg size, metabolism, and water content of turkey eggs.

New evidence of anuran oviducal pars recta involvement on gamete interaction

AbstractCoelomic oocytes of the toad Bufo arenarum are not fertilizable when inseminated in egg water that assures fertilization of dejellied uterine eggs. However, when coelomic oocytes were pretreated with an extract from oviducal pars recta (PRE) and inseminated in egg water, a high frequency of fertilization was obtained.In this study the effect of PRE on acrosome breakdown (AB) was studied by means of vitelline envelope (VE) lysis and fertility tests with B. arenarum sperm, and by direct observations with the light microscope of the AB with Leptodactylus chaquensis sperm. The coelomic envelope becomes sensitive to lysin solution only after PRE treatment. The addition of sperm to PR‐treated oocytes, in a medium containing egg water, resulted in a marked swelling and softening of the VE. But this lytic effect by sperm can be observed only when egg water was present in the medium. These results indicate that jelly‐molecules are necessary for the acrosome process to begin and that PR components engulfed in the VE are not capable of inducing AB by themselves. Likewise, incubation of B. arenarum sperm with PRE did not impair their fertilizing capacity and the supernatant of this incubation medium did not have typical VE lytic activity.Moreover, when the effect of PRE on AB was studied by direct observation of L. chaquensis sperm, it was found that PRE neither induces AB nor modifies its time‐course.

Partial specific volumes of lipid and water in mixtures of egg lecithin and water

We describe in this paper measurements of the partial specific volumes of lipid (upsilon L) and water (upsilon W) in mechanical mixtures of egg yolk lecithin and water over a range of hydrations (5-55 wt% water) that includes the region at which excess water appears. upsilon L and upsilon W are found to be very nearly 1 cm3/g over the entire range. The water activities of the mixtures were also determined and found to be the same as for lipid deposited as oriented multilayers on solid substrates.

Cell cycle changes in water properties in sea urchin eggs.

This study concerned changes in the motional properties of cellular water during the first cell cycle of fertilized sea urchin eggs (Lytechinus variegatus). There was a significant decrease in proton NMR T1 relaxation time and in cytoplasmic ice crystal growth during mitosis and a significant increase in T1 time and cytoplasmic ice crystal size during cleavage. This was not caused by egg water content changes as reflected by egg volume measurements. Removal of both the fertilization membrane and the hyaline layer shortly after fertilization did not alter the pattern of T1 time changes at mitosis and cleavage as compared to whole eggs; thus, the pattern of T1 time changes was attributed to intracellular events. Treatment of fertilized eggs with cytochalasin B, an inhibitor of actin polymerization, did not block the fall in T1 time at mitosis, but did block cytokinesis and the increase in T1 time, which normally occurred at cleavage. A significant pattern of actin disassembly and reassembly at mitosis and cytokinesis was found by studies on the total amount of monomeric actin (G actin) using the DNase I assay. This led to the hypothesis that the observed changes in T1 time and ice crystal size during the first cell cycle were due to the depolymerization and polymerization of cytoplasmic actin. To test this, the effect of the in vitro polymerization of purified actin on the T1 time and on ice crystal growth was examined. It was concluded that changes in the T1 time and ice crystal growth upon polymerization of actin in vitro resembled the changes seen in vivo. These results suggest that changes in the motional properties of cytoplasmic water during the first cell cycle are due, at least in part, to the state of polymerization of cytoplasmic actin.

Failure to turn eggs during incubation: effects on embryo weight, development of the chorioallantois and absorption of albumen.

Turning eggs during incubation is essential for good hatchability. In the present paper additional effects on the development of the chorioallantois, absorption of albumen and growth of the embryo are recorded. The ability of an unturned egg to hatch was not affected by egg weight, egg shell porosity or water loss during incubation. The ability of the chorioallantois to spread around the inner surface of the inner shell membrane and the degree of absorption of the residual albumen affected the growth of the embryo and its ability to hatch. Unturned eggs hatched later than eggs which were turned throughout incubation.

Dissociation between several egg parameters in two quail strains genetically selected for resistance or sensitivity to acute hypoxia

1. 1. Eggs laid by females of two strains of Japanese quail, selected in a divergent way towards survival to an acute normobaric hypoxic challenge, were compared for their mass, the mass and the thickness of their eggshell and their water conductance ( g h 2o ). 2. 2. Adults and embryos of the Ls+ strain survive at 70%, whereas those of the Ls-strain survive only at 20% to the acute hypoxia. 3. 3. While the birds of both sexes of each strain do not statistically differ either by their body masses or by various physiological and biochemical parameters, the eggs laid by the females of these strains differ significantly (0.001 < P < 0.01) in mass, eggshell thickness, egg shell mass and water vapor conductance ( g h 2o ). 4. 4. Ls-quail lay lighter eggs with lighter and thinner eggshells and with higher g h 2o than Ls+ quail. 5. 5. Crossing these two strains gives f 1 hybrids (Ls±) whose females lay eggs that are statistically (0.001 < P <0.05) different from those laid by Ls+ in egg masses and shell masses, and statistically (0.001 < P <0.05) different from those of Ls-in shell masses, shell thicknesses and g h 2o .

Induction of the acrosomal reaction in sperm from the white sturgeon, Acipenser transmontanus.

Sperm from the white sturgeon, Acipenser transmontanus possess an acrosome while the eggs possess numerous micropyles. The sperm undergo an acrosome reaction that includes exocytosis and process formation. This acrosomal reaction can be induced in freshwater with ionophore A23187, high pH, high Ca++, or egg water. In addition, this event is dependent on extracellular Ca++ and Mg++. Upon immersion of eggs in freshwater, a water-soluble jelly layer hydrates and forms a highly adhesive coating surrounding the eggs. Jelly release and hydration appears dependent on both a trypsin-like protease and Ca++ and Mg++ ions. Isolated egg jelly (110,000 dalton glycoprotein) does not possess acrosome reaction inducing activity. The acrosome reaction inducing activity in egg water resides in a water-soluble 66,000 dalton glycoprotein. Egg water appears species specific in its ability to elicit a response. Prior to freshwater exposure, the egg envelope possesses a water-insoluble glycoprotein with a molecular weight of 70,000 daltons. When isolated from polyacrylamide gels, the 70,000 dalton component induces acrosome reactions in a species specific manner. Following freshwater exposure, the egg envelope possesses the water-soluble 66,000 dalton glycoprotein in addition to the 70,000 dalton component. The 70,000-66,000 dalton conversion can be blocked by incubating eggs in freshwater containing inhibitors of trypsin-like proteases. Both the 66,000 dalton and 70,000 dalton glycoproteins originate and reside in layer three of the egg envelope.

Behavioral and Morphological Adaptations by Galapagos Land Iguanas (Conolophus subcristatus) to Water and Energy Requirements of Eggs and Neonates

We examine the importance of both the hydric environment of naturally incubating reptilian eggs and the energetic needs of hatchlings via an investigation of reproduction in Galapagos land iguanas ( Conolophus subcristatus ). Hatching success of egg clutches and the size of subsequent hatchlings are both positively correlated with the water potential of natural nests, as predicted from previous laboratory experiments. Water potentials representing optimal incubation environments are available for only a brief period in nature, and depend upon the same seasonal rainfall as does food abundance for the emerging hatchlings. The temporal placement of the reproductive season of Conolophus subcristatus balances these conflicting needs for water by eggs and energy by hatchlings. Oviposition occurs slightly before suitable water potentials are reached and hatchling emergence occurs after the peak in food abundance. Morphological adaptations by Conolophus subcristatus to their precarious reproductive phenology include greater amounts of albumen in their eggs, and greater energy reserves in emergent hatchlings than most other lizard species. These adaptations lessen the severity of an arid environment where water becomes available for periods too short to allow both oviposition and hatching to be temporally placed in an optimal manner.

Interrelations Among Water and Energy Relations of Reptilian Eggs, Embryos, and Hatchlings

Reptilian eggs previously categorized with respect to the flexibility of eggshells appear to fall into two groups: endohydric eggs are those that are invested, by the female parent at the time of oviposition, with all of the water necessary to complete embryogenesis; and ectohydric eggs which need to absorb water from the nest medium tocomplete embryogenesis. Eggs of the Galapagos land iguana are unusual among most lepidosaurians by having very permeable parchment shells, but containing a large albumen (apparently serving as a reservoir of water for the embryo). It appears that the eggs of Galapagos land iguanas can exploit an endohydric habit without the rigid, impermeable shell seen in other endohydric eggs. This ability appears to be mediated by two factors: eggs of Galapagos land iguanas are laid in dry soils which are essentially impermeable to water, and the very large eggs of land iguanas have a relatively small surface area tovolume ratio which results in a relatively small exchange of water across the eggshell. It appears too that the water relations of Galapagos land iguana eggs will affect the energetics of both the contained embryo and the subsequent hatchling. Without adequate water, land iguana eggs will produce hatchlings that are both smaller and possess less fat to sustain thejuvenile during the first year of life.

Gamete interaction in the white sturgeon Acipenser transmontanus: a morphological and physiological review

Sturgeon gametes differ from those of most fish in that the sperm possess acrosomes that undergo exocytosis and filament formation while the eggs possess numerous micropyles. Acipenser transmontanus eggs are encased by multilayered envelopes that consist of outer adhesive jelly coats and three structured layers interior to the jelly. The glycoprotein jelly layer only becomes adhesive upon exposure to freshwater. The layer interior to the jelly, layer 3, is the other carbohydrate-containing component of the egg envelope. This layer consists of a water-insoluble glycoprotein that, upon freshwater exposure, is hydrolyzed by a trypsinlike protease to yield a water-soluble, lower molecular weight carbohydrate-containing component. This component can be identified in the surrounding medium when unfertilized eggs are incubated in freshwater. This egg water component elicits acrosome reactions only in homologous sperm. The A. transmontanus sperm acrosome reaction is a Ca++ and/or Mg++ dependent event that includes the formation of a 10 μ long fertilization filament. A. transmontanus fertilization can occur at low sperm per egg ratios; however, crossfertilization of A. transmontanus eggs with lake sturgeon, A. fluvescens, sperm results in a very low number of fertilized eggs, even at high sperm per egg ratios. The morphological, physiological, and biochemical phenomenon reviewed in this paper are related to the environment in which they occur. Also, the possible role of the acrosome and the presence of numerous micropyles are discussed.

Water and Heat Exchange between Parchment-Shelled Reptile Eggs and Their Surroundings

important effect on the exchange of heat and water by the eggs. Differences in the patterns of water exchange reported for reptile eggs can be attributed to quantitative differences in the thermal regimes in which the eggs are incubated. The greater the thermal conductivity of the substrate in which eggs are incubating, the more water the eggs will take up under wet conditions and the less water they will lose under dry conditions. Large eggs will be more strongly buffered against water exchange than small eggs and, in similar conditions, they will exchange relatively less water than small eggs. The effect is due to the relationships between egg mass, surface area and water vapor conductance. In this respect, an egg clutch may be viewed as a very large egg which will be much less sensitive to its hydric environment than a single, smaller egg. Temperature and water vapor pressure differences existing inside egg clutches will determine the exchange of heat and water within the clutch and influence the exchange between the clutch and the substrate surrounding it.

A Test for Regulation of Egg Dehydration by Control of Shell Conductance in Mourning Doves

Previous studies tested in domesticated species the hypothesis that dehydration of avian eggs is regulated by short-term physiological adjustment of shell structure by females in response to environmental variation. I tested this hypothesis in a natural population of mourning doves (Zenaida macroura) exposed to a large seasonal change in environmental humidity. Measurement of shell conductance to water vapor, nest humidity, internal egg vapor pressure, and egg water loss reveal that females do not seasonally adjust eggshell conductance to cope with this humidity shift; nor is egg dehydration regulated by parental control of nest humidity. Consequently, nest humidity increases twofold and egg water loss declines an average of 25% with the onset of the humid season.

Demonstration of sperm chemotaxis in Echinodermata: Asteroidea, Holothuroidea, Ophiuroidea

AbstractThe sperm of starfish (Asteroidea), sea cucumbers (Holothuroidea), and brittle stars (Ophiuroidea) are chemotactically attracted to the tip of a micropipette releasing very small volumes of egg water or seawater solution of an alcoholic extract of ovaries or spawned eggs. The sperm are unresponsive to injections of seawater or a weak solution of ammonium chloride in seawater. No other echinoderm tissue tested yields an extract with sperm‐attracting activity. A complex set of species‐specificities has been demonstrated between many of the genera and species used in these experiments. Plotting of the paths of chemotactic sperm reveals that they approach the tip of the pipette along a path consisting of small loops alternating with straight segments orientated directly up the gradient. This is similar to the chemotactic behavior previously reported for the sperm of hydrozoans, molluscs, and urochordates. Sperm velocity does not change in response to the sperm attractant. Attracted sperm remain motile long after they have been attracted and do not agglutinate. In at least some cases the attraction response is reversible. This is the first direct evidence of sperm chemotaxis in echinoderms.

Egg Water Loss, Shell Water-Vapor Conductance, and the Incubation Period of the Gray-Backed Tern (Sterna lunata)

The incubation period (30.3 days) of the Gray-backed Tern (Sterna lunata) is longer than would be expected from the mass of the freshly-laid egg. Measured values for the water loss from unpipped eggs, the water-vapor conductance and the functional pore area of the shell, and the number of pores in the shell are all lower than predictions based solely on fresh-egg mass, but are more closely approximated by equations incorporating incubation period as well as the egg's mass. The total water loss from the egg represents 14.7% of its mass when freshly laid. The interval between the first star-fracture of the shell and the hatching of the chick is 13.5% of the total incubation period, but accounts for 30.8% of the egg's total water loss.

An egg envelope component induces the acrosome reaction in sturgeon sperm.

The acrosome reaction in Acipenser transmontanus sperm can be induced by a 66,000 dalton glycoprotein that is present in Layer 3 (L3) of the egg envelope and in egg water only following exposure of the eggs to fresh water. When egg water is fractionated on Sepharose CL 6B, the 66,000 dalton glycoprotein-containing fractions possess acrosome reaction inducing activity. Egg water may be species-specific in its ability to elicit the acrosome reaction, as demonstrated by the fact that it has no effect on the sperm of Acipenser fulvescens. Egg jelly possesses no acrosome reaction, inducing activity. The major carbohydrate-containing component of the egg envelope is L3, a layer that contains galactose residues. L3 possesses a 70,000 dalton glycoprotein prior to freshwater exposure and lacks the 66,000 dalton component. If isolated from polyacrylamide gels, the 70,000 dalton glycoprotein elicits acrosome reactions in what appears to be a species specific manner. After freshwater exposure, L3 contains both the 70,000 dalton glycoprotein and the 66,000 dalton glycoprotein that is also present in egg water. The appearance of the 66,000 dalton inducer can be blocked by the incubation of eggs in fresh water containing inhibitors of trypsin activity. Thus, the soluble inducer in egg water may be proteolytically derived from a higher molecular weight complex in the egg envelope.

An acrosome reaction in sperm from the white sturgeon, Acipenser transmontanus

AbstractThe A. transmontanus sperm possesses an elongate main body, a conspicuous acrosome, a midpiece, and a flagellum. Three membrane‐lined nuclear channels that are helically arranged extend from the acrosomal region to the midpiece. Sperm heads contain material that comigrates on sodium dodecyl sulfate (SDS)‐gels with actin. An acrosome reaction can be induced in freshwater with ionophore A23187, high pH, high Ca++, or egg water. This acrosomal reaction is a Ca+‐Mg+‐dependent event. The resulting acrosomal process (10 μm) originates from the subacrosome region and the nuclear channels. Non‐filamentous actin apparently polymerizes and forms the process.

Egg Size Variation in Central Texas Populations of Etheostoma spectabile (Pisces: Percidae)

Variation in size of ripe eggs (dry weight) was investigated in 5 central Texas populations of the orangethroat darter, Etheostoma spectabile. In natural populations, egg weight varied within populations over the course of a single breeding season, among populations from different localities and among females collected at the same time and place. In general, eggs were heaviest when water temperatures were coldest, but correlations between egg size and water temperature measured in the field were not always significant. Laboratory observations revealed that individual females can produce multiple clutches with significant interclutch variation in egg weight. Egg size in many, but not all, females varied inversely with laboratory water temperature. Despite individual plasticity, significant among-female and geographic differences in egg weight were apparent in the laboratory, suggesting that egg size has non-proximate (e.g., developmental or genetic) as well as proximate environmental determinants.

Microclimate of the nest and egg water loss of the Eider Somateria mollissima and other waterfowl in Spitsbergen

Temperature gradients in the nest and within the egg. nest humidity as well as eggshell conductance and rate of egg water loss of the Eider Somareria mollissrma and other uaterfowl were studied at Ny-Alesund. Spitsbergen (78% latitude). These studies suggest a specific interrelationship between eggshell conductance and maintenance of an appropriate temperature and humidity environment of the nest. resulting in an egg water loss rate which is optimal for hatching success. In spite of low ambient temperatures of less than 3°C and very low absolute humidities of less than 4 torr (similar to those found in hot deserts). the nest's microclimate and rate of mater loss were similar to those reported for nests and eggs in temperate climates.