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PubMed1992

Fusion of membranes during fertilization. Increases of the sea urchin egg's membrane capacitance and membrane conductance at the site of contact with the sperm.

The early events of fertilization that precede and cause activation of an egg have not been fully elucidated. The earliest electrophysiological change in the sea urchin egg is a sperm-evoked increase of the egg's membrane conductance. The resulting depolarization facilitates entry of the fertilizing sperm and precludes the entry of supernumerary sperm. The sequence of the increase in the egg's membrane conductance, gamete membrane fusion, egg activation, and sperm entry, including causal relationships between these events, are not known. This study reports the use of whole egg voltage clamp and loose patch clamp to monitor simultaneously changes of membrane conductance and capacitance at the site of sperm-egg contact. Measurements were made during sperm-egg interactions where sperm entry readily proceeded or was precluded by maintaining the egg's membrane potential either at large, negative values or at positive values. Whenever the sperm evoked an increase of the egg's membrane conductance, that increase initiated abruptly, was localized to the site of sperm attachment, and was accompanied by a simultaneous abrupt increase of the membrane capacitance. This increase of capacitance indicated the establishment of electrical continuity between gametes (possibly fusion of the gametes' plasma membranes). If sperm entry was blocked by large negative membrane potentials, the capacitance cut off rapidly and simultaneously with a decrease of the membrane conductance, indicating that electrical continuity between gametes was disrupted. When sperm entry was precluded by positive membrane potentials, neither conductance nor capacitance increased, indicating that sperm entry was halted before the fusion of membranes. A second, smooth increase of capacitance was associated with the exocytosis of cortical granules near the sperm in eggs that were activated. Electrical continuity between the gametes always preceded activation of the egg, but transient electrical continuity between the gametes alone was not always sufficient to induce activation.

Animals↗
PubMed2005

Egg-laying preference of female fungus gnat Bradysia sp. nr. coprophila (Diptera: Sciaridae) on three different soilless substrates.

Fungus gnats, Bradysia spp., are major insect pests in greenhouses. Adult female fungus gnats prefer to lay eggs in growing medium that is microbially active or that contains high amounts of peat moss or hardwood bark. However, egg-laying preference has not been demonstrated quantitatively. This study was designed to determine whether fungus gnat Bradysia sp. nr. coprophila females prefer any of the three soilless growing media provided. The three soilless growing media tested were Metro-Mix 560 with Scott's Coir, Sunshine LC1 Mix, and Universal SB 300 Mix. Initially, the egg-laying potential of the fungus gnat species used in this study was assessed by dissecting mated females after 24, 48, and 72 h. For the egg-laying preference experiment, adults that emerged from pupae were aspirated into a plastic vial, sexed, and then allowed to mate for 24 h. Individual mated females were released into an experimental chamber (15 by 15 by 5-cm plastic container) consisting of four 6-cm petri dishes, three of which contained soilless growing media and one with filter paper (control). In total, there were 50 experimental chambers, with each chamber representing a replication. Females remained in the experimental chambers for 48 h after which the growing media were processed using a flotation/extraction method. The number of eggs laid by female fungus gnats ranged from 21 to 217 with most eggs recovered after 48 h (141.0 +/- 9.3). There were no significant differences among the three soilless growing media in terms of number of eggs laid, although all three growing media were significantly different from the filter paper with higher numbers of eggs laid in the soilless growing media than the filter paper. Despite no significant difference among the growing media in the number of eggs laid, fungus gnat females tended to lay eggs more often, based on the number of petri dishes in which at least one egg was laid, in Metro-Mix 560 (86%) than Sunshine LC1 (66%), Universal SB 300 (52%), or filter paper (18%). Based on the results of this study, female fungus gnats may not prefer a specific growing medium for oviposition. However, fungus gnat females may rely on other factors not tested in this study such as moisture content and volatiles emitted from growing media in their decision where to lay eggs.

Animals↗
PubMed1994

Changes in morphology, sperm penetration and fertilization of ovulated hamster eggs induced by oviductal exposure.

In the human, mature eggs at the pre-ovulatory follicular stage placed into the oviduct via gamete intra-Fallopian transfer (GIFT) establish more implantations and pregnancies than do those for standard in-vitro fertilization and embryo transfer (IVF). Previous studies in the hamster have shown that mature follicular eggs are less readily penetrated by spermatozoa than oviductal eggs. This study examines whether ovulation or pre-fertilization exposure to the oviduct per se affects sperm penetration and fertilization of mature ova. Three types of eggs were used: pre-ovulatory, follicular [12 h post-human chorionic gonadotrophin (HCG), 1-1.5 h pre-ovulation], and ovulated (bursal and oviductal, both 15 +/- 0.5 h post-HCG). Bursal eggs were obtained by ligating the infundibulum on one or both sides of the tract. The morphological changes in eggs due to oviductal exposure were quantified using computerized image analysis. Cumulus-free follicular and bursal eggs were significantly less penetrated than oviductal eggs 1 h post-insemination (36, 39 and 62%, respectively). Cumulus-intact oviductal compared to bursal eggs, paired within females, were fertilized at a significantly higher rate (4 h post-insemination; 89 and 58%, respectively). Fresh oviductal and bursal eggs had equivalent cell diameters (79 microns) and zona thickness (15-15.8 microns), but oviductal compared with bursal eggs had larger zonae (119 and 116 microns, respectively) and perivitelline volumes (107 and 47 pl). Oviductal, but not bursal, zonae had the oviductal glycoprotein, oviductin, bound to them. We conclude that prefertilization oviductal exposure and not ovulation or time post-HCG alters the morphology and fertilizability of eggs.

Animals↗
PubMed1996

Intracellular pH of rat eggs is not affected by fertilization and the resulting calcium oscillations.

Penetration of the oocyte by a spermatozoon is the first in the series of events resulting in the transition of the egg from a quiescent to a proliferative state. A critical regulatory role for intracellular calcium ([Ca2+]i) ion activity has been demonstrated in all species studied so far. On the other hand, it has been demonstrated that the intracellular pH (pHi) changes, but only in a small number of species. This change also has been proposed as one of the most important events in egg activation. The present study was undertaken to monitor pHi in rat eggs during fertilization, using the membrane-permeable indicator BCECF-AM and fluorescence ratio imaging. Furthermore, we proposed to evaluate the relationship between pHi and [Ca2+]i changes during egg activation. We found that the ovulated rat egg has a cytoplasmic pH significantly different from that of the follicular oocyte. Insemination with capacitated sperm resulted in a microscopically visible sperm attachment, yet no change in pHi was observed. Eggs double-loaded with fura-2-AM and BCECF-AM before insemination were used to measure [Ca2+]i and pHi simultaneously. Eggs with a normal pattern of [Ca2+]i transients (i.e., fertilized eggs) did not show any change in pHi at least for 30 min following sperm binding. Data for eggs fertilized in vivo were recorded at later times after sperm binding; these served to exclude the possibility of a transient change that occurs between sperm-egg interaction and the pronuclear stage. We conclude that the pHi of rat eggs does not change during fertilization and therefore that fertilization-induced [Ca2+]i changes do not affect pHi in these eggs.

Animals↗
PubMed2002

Involvement of calcium signaling and the actin cytoskeleton in the membrane block to polyspermy in mouse eggs.

This study examines the effects of actin microfilament-disrupting drugs on events of fertilization, with emphasis on gamete membrane interactions. Mouse eggs, freed of their zonae pellucidae, were treated with drugs that perturb the actin cytoskeleton by different mechanisms (cytochalasin B, cytochalasin D, jasplakinolide, latrunculin B) and then inseminated. Cytochalasin B, jasplakinolide, and latrunculin B treatments resulted in a decrease in the percentage of eggs fertilized and the average number of sperm fused per egg. However, cytochalasin D treatment resulted in an increase in the average number of sperm fused per egg and the percentage of polyspermic eggs. This increase in polyspermy occurred despite the observation that cytochalasin D treatment caused a decrease in sperm-egg binding and did not affect spontaneous acrosome reactions or sperm motility. This suggested that cytochalasin D-treated eggs had an impaired ability to establish a block to polyspermy at the level of the plasma membrane. The effect of cytochalasin D on the block to polyspermy was not due to a general disruption of egg activation because sperm-induced calcium oscillations and cortical granule exocytosis were similar in cytochalasin D-treated and control eggs. However, buffering of intracellular calcium levels with the calcium chelator BAPTA-AM resulted in an increase in polyspermy. Together, these data suggest that a postfertilization decrease in egg membrane receptivity to sperm requires functions of the egg actin cytoskeleton that are disrupted by cytochalasin D. Furthermore, egg activation-associated increased intracellular calcium levels are necessary but not sufficient to affect postfertilization membrane dynamics that contribute to a membrane block to polyspermy.

Acrosome↗
PubMed2001

The Acp26Aa seminal fluid protein is a modulator of early egg hatchability in Drosophila melanogaster.

Drosophila melanogaster male accessory gland proteins (Acps) that are transferred in the ejaculate with sperm mediate post-mating competition for fertilizations between males. The actions of Acps include effects on oviposition and ovulation, receptivity and sperm storage. Two Acps that modulate egg production are Acp26Aa (ovulin) and Acp70A (the sex peptide). Acp26Aa acts specifically on the process of ovulation (the release of mature eggs from the ovaries), which is initiated 1.5 h after mating. In contrast, sperm storage can take as long as 6-9 h to complete. Initial ovulations after matings by virgin females will therefore occur before all sperm are fully stored and the extra eggs initially laid as a result of Acp26Aa transfer are expected to be inefficiently fertilized. Acp26Aa-mediated release of existing eggs should not cause a significant energetic cost or lead to a decrease in female lifespan assuming, as seems likely, that the energetic cost of egg laying comes from de novo egg synthesis (oogenesis) rather than from ovulation. We tested these predictions using Acp26Aa(1) mutant males that lack Acp26Aa but are normal for other Acps and Acp26Aa(2) males that transfer a truncated but fully functional Acp26Aa protein. Females mating with Acp26Aa(2) (truncation) males that received functional Acp26Aa produced significantly more eggs following their first matings than did mates of Acp26Aa(1) (null) males. However, as predicted above, these extra eggs, which were laid as a result of Acp26Aa transfer to virgin females, showed significantly lower egg hatchability. Control experiments indicated that this lower hatchability was due to lower rates of fertilization at early post-mating times. There was no drop in egg hatchability in subsequent non-virgin matings. In addition, as predicted above, females that did or did not receive Acp26Aa did not differ in survival, lifetime fecundity or lifetime progeny, indicating that Acp26Aa transfer does not represent a significant energetic cost for females and does not contribute to the survival cost of mating. Acp26Aa appears to remove a block to oogenesis by causing the clearing out of existing mature eggs and, thus, indirectly allowing oogenesis to be initiated immediately after mating. The results show that subtle processes coordinate the stimulation of egg production and sperm storage in mating pairs.

Animals↗
PubMed2002

Parental care of a cowbird host: caught between the costs of egg-removal and nest predation.

Avian brood parasites reduce host fitness through the addition of parasitic eggs and the removal of host eggs. Both parasitic egg-addition and host egg-removal may be important sources of selection on host behaviour, creating fitness trade-offs with selection imposed by nest predation. However, the relative costs hosts suffer from egg-addition and host egg-removal and the responses to these costs are largely unstudied. Through experimental manipulations and observations, we demonstrate that increased nest attentiveness by female yellow warblers (Dendroica petechia) reduces the cost of brood parasitism by reducing egg-removal by brown-headed cowbirds (Molothrus ater). However, female attentiveness does not reduce the addition of parasitic eggs. Experimentally parasitized females respond to the threat of egg-removal by increasing nest attentiveness. Increased attentiveness, however, reduces time for females to gather food and requires males to visit the nest more often to feed incubating females. This increased activity in turn increases the risk of nest predation. Thus, brood parasitism (specifically egg-removal) and nest predation produce conflicting selection on incubation strategies, as parasitized hosts are caught between the costs of egg-removal by brood parasites, and the costs of increased nest predation if the female spends more time on the nest to reduce egg-removal.

Animals↗
PubMed2004

Worker policing by egg eating in the ponerine ant Pachycondyla inversa.

We investigated worker policing by egg eating in the ponerine ant Pachycondyla inversa, a species with morphologically distinct queens and workers. Colonies were split into one half with the queen and one half without. Workers in queenless colony fragments started laying unfertilized male eggs after three weeks. Worker-laid eggs and queen-laid eggs were introduced into five other queenright colonies with a single queen and three colonies with multiple queens, and their fate was observed for 30 min. Significantly more worker-laid eggs (range of 35-62%, mean of 46%) than queen-laid eggs (range of 5-31%, mean of 15%) were eaten by workers in single-queen colonies, and the same trend was seen in multiple-queen colonies. This seems to be the first well-documented study of ants with a distinct caste polymorphism to show that workers kill worker-laid eggs in preference to queen-laid eggs. Chemical analyses showed that the surfaces of queen-laid and worker-laid eggs have different chemical profiles as a result of different relative proportions of several hydrocarbons. Such differences might provide the information necessary for differential treatment of eggs. One particular alkane, 3,11-dimeC27, was significantly more abundant on the surfaces of queen-laid eggs. This substance is also the most abundant compound on the cuticles of egg layers.

Aggression↗
PubMed2002

Dose-response effect of egg-phosphatidylcholine on maze-learning ability and fatty acid composition of plasma and brain in aged mice fed an n-3 fatty acid-deficient diet.

BACKGROUND/AIMS: We investigated the dose-response effect of egg-phosphatidylcholine (PC) on the maze-learning ability and brain fatty acid composition in aged mice. METHOD: Male Crj:CD-1 mice aged 18 months were fed the following diets for 4 months: (i) 5 g palm oil/100 g diet (n-3-deficient control group); (ii) 1 g egg-PC/100 g diet plus 4 g palm oil/100 g diet (egg-PC 1% group); (iii) 2.5 g egg-PC/100 g diet plus 2.5 g palm oil/100 g diet (egg-PC 2.5% group), and (iv) 5 g egg-PC/100 g diet (egg-PC 5% group). Maze-learning ability was assessed 3 months after the start of the experiment. All animals were maintained on the n-3 fatty acid-deficient diets to examine the direct effect of egg-PC on maze behavior. The time required to reach the maze exit and the number of times that a mouse strayed into blind alleys in the maze were measured in 3 trials every 4 days. RESULTS: Our results showed that the 2.5 and 5% egg-PC groups needed less (p < 0.05) time to find the exit and strayed into blind alleys fewer times (p < 0.05) than the control group. In order to determine the relationship between maze-behavior and brain docosahexaenoic acid (DHA) and arachidonic acid (AA) levels in aged mice fed various doses of egg-PC, the plasma and brain fatty acid composition was examined. Dose-response increases in the percentage of DHA were found in plasma lipids. However, based on our data on the brain fatty acid composition of mice fed various doses of egg-PC, no significant differences in the percentages of DHA and AA among the dietary groups were observed. CONCLUSION: These results suggest that the intake of egg-PC improves maze-learning ability in aged mice fed n-3 fatty acid-deficient diets but it does not influence the percentage of brain DHA and AA.

Aging↗
PubMed1985

Role of granulocyte oxygen products in damage of Schistosoma mansoni eggs in vitro.

The objectives of this study were to describe the ultrastructure of granulocyte-Schistosoma mansoni egg interaction and to determine the role of reduced oxygen products as effectors of cell-mediated damage to the parasite target. Granulocytes attached to the parasites and closely applied their plasma membranes to the microspicules of the egg shell 30 min after mixing in the presence of immune serum. By 4 h, the egg shell was fractured and granulocyte pseudopodia extended toward the underlying miracidium. Granulocyte attachment to eggs resulted in release of O2- (0.30-0.52 nmol/min per 2 X 10(6) cells) and accumulation of H2O2 (0.14-0.15 nmol/min) in the presence of antibody or complement. Granulocytes reduced egg tricarboxylic-acid cycle activity and hatching by 28.3 +/- 0.9 and 35.2 +/- 2.8%, respectively (cell-egg ratio of 1,000: 1). Exogenous superoxide dismutase (10 micrograms/ml) inhibited granulocyte toxicity for egg metabolic activity (3.0 +/- 2.1% reduction in acetate metabolism vs. 28.3 +/- 0.9% decrease in controls without superoxide dismutase, P less than 0.0005) and hatching (12.5 +/- 1.8% reduction, P less than 0.0005), whereas catalase and heparin had no effect. Inhibitors of myeloperoxidase (1 mM azide, cyanide, and methimazole) augmented granulocyte-mediated toxicity of egg tricarboxylic-acid cycle activity (44-58% reduction in activity vs. 31 and 35% reduction in controls), suggesting that H2O2 released from cells was degraded before reaching the target miracidium. Oxidants generated by acetaldehyde (2 mM)-xanthine oxidase (10 mU/ml) also decreased egg metabolic activity and hatching by 62.0 +/- 9.0 and 38.7 +/- 7.3%, respectively. Egg damage by the cell-free system was partially prevented by superoxide dismutase (26.5 +/- 4.2% reduction in egg tricarboxylic-acid activity) and completely blocked by catalase (0% reduction in activity). These data suggest that granulocyte-mediated toxicity for S. mansoni eggs is dependent on release of O2- or related molecules. These oxygen products, unlike H2O2, may readily reach the target miracidium where they may be converted to H2O2 or other microbicidal effector molecules.

Acetaldehyde↗
PubMed1991

Identification of a cytoskeletal protein localized in the myoplasm of ascidian eggs: localization is modified during anural development.

The myoplasm of ascidian eggs is a localized cytoskeletal domain that is segregated to presumptive larval tail muscle cells during embryonic development. We have identified a cytoskeletal protein recognized by a vertebrate neurofilament monoclonal antibody (NN18) which is concentrated in the myoplasm in eggs and embryos of a variety of ascidian species. The NN18 antigen is localized in the periphery of unfertilized eggs, segregates with the myoplasm after fertilization, and enters the larval tail muscle cells during embryonic development. Western blots of one-dimensional and two-dimensional gels showed that the major component recognized by NN18 antibody is a 58 x 10(3) Mr protein (p58), which exists in at least three different isoforms. The enrichment of p58 in the Triton X-100-insoluble fraction of eggs and its reticular staining pattern in eggs and embryos suggests that it is a cytoskeletal protein. In subsequent experiments, p58 was used as a marker to determine whether changes in the myoplasm occur in eggs of anural ascidian species, i.e. those exhibiting a life cycle lacking tadpole larvae with differentiated muscle cells. Although p58 was localized in the myoplasm in eggs of four urodele ascidian species that develop into swimming tadpole larvae, this protein was distributed uniformly in eggs of three anural ascidian species. The eggs of two of these anural species contained the actin lamina, another component of the myoplasm, whereas the third anural species lacked the actin lamina. There was no detectible localization of p58 after fertilization or segregation into muscle lineage cells during cleavage of anural eggs. NN18 antigen was uniformly distributed in pre-vitellogenic oocytes and then localized in the perinuclear zone during vitellogenesis of urodele and anural ascidians. Subsequently, NN18 antigen was concentrated in the peripheral cytoplasm of post-vitellogenic oocytes and mature eggs of urodele, but not anural, ascidians. It is concluded that the myoplasm of ascidian eggs contains an intermediate filament-like cytoskeletal network which is missing in anural species that have modified or eliminated the tadpole larva.

Actins↗
PubMed1978

Induction of cleavage in nucleated and enucleated frog eggs by injection of isolated sea-urchin mitotic apparatus.

Mitotic apparatus (MA) were isolated in glycerol-dimethylsulphoxide solution (MTME) from zygotes of sea urchins (Stronglyocentrotus purpuratus). Freshly isolated MA were stored in 1/10 strength MTME for varying periods of time and were then injected into unfertilized frog (Rana pipiens) eggs. These injections induced 40-60% of the recipient frog eggs to initiate cleavage, resulting in the formation of blastula cell clusters. The cleavage-inducing activity of MA stored in 1/10 MTME at room temperature decreased with time of storage in 1/10 strength MTME, and disappeared by about 6 h. There was no change in the ultrastructure of MA during storage. MA isolated and stored in MTME at room temperature had a constant level of cleavage-inducing activity during the first 48 h of storage, but this activity slowly declined upon further storage; almost no activity was left after 3 weeks. MA isolated in hexylene glycol (HG) and immediately transferred into MTME were compared with MA isolated in MTME; both MA had the same cleavage-inducing activity on the day of isolation, after which the MA isolated in HG quickly lost activity. On the other hand, MA isolated and stored in HG had little cleavage-inducing activity when tested 3 h following isolation. Cleavage-inducing agent (CIA) isolated from frog brains induced cleavage and blastula formation when injected into nucleated frog eggs, but had no such activity when injected into enucleated frog eggs. MA isolated in MTME induced cleavage and blastula formation in enucleated frog eggs as well as in nucleated frog eggs. Cytological examination revealed that blastula cells which developed from MA-injected enucleated eggs contained Feulgennegative nuclei, whereas cells which developed from CIA-injected nucleated eggs contained Feulgen-positive nuclei. These results suggest that sea-urchin nuclear materials participate in mitosis in frog eggs. Isolated MA which had been stored in MTME for 3 weeks and which exhibited little cleavage-inducing activity were injected together with frog brain CIA into either normal or enucleated eggs; normal recipient eggs cleaved with significantly higher frequencies (70%) than those injected with CIA alone (40%). Furthermore, enucleated eggs injected with CIA alone failed to cleave, while those injected with MA and CIA together cleaved with significant frequencies (overall 29%). This result suggests a cooperative interaction between CIA and the inactivated MA to restore the cleavage-inducing activity of MA.

Animals↗
PubMed2004

Are Src family kinases involved in cell cycle resumption in rat eggs?

The earliest visible indications for the transition to embryos in mammalian eggs, known as egg activation, are cortical granules exocytosis (CGE) and resumption of meiosis (RM); these events are triggered by the fertilizing spermatozoon through a series of Ca2+ transients. The pathways, within the egg, leading to the intracellular Ca2+ release and to the downstream cellular events, are currently under intensive investigation. The involvement of Src family kinases (SFKs) in Ca2+ release at fertilization is well supported in marine invertebrate eggs but not in mammalian eggs. In a previous study we have shown the expression and localization of Fyn, the first SFK member demonstrated in the mammalian egg. The purpose of the current study was to identify other common SFKs and resolve their function during activation of mammalian eggs. All three kinases examined: Fyn, c-Src and c-Yes are distributed throughout the egg cytoplasm. However, Fyn and c-Yes tend to concentrate at the egg cortex, though only Fyn is localized to the spindle as well. The different localizations of the various SFKs imply the possibility of their different functions within the egg. To examine whether SFKs participate in the signal transduction pathways during egg activation, we employed selective inhibitors of the SFKs activity (PP2 and SU6656). The results demonstrate that RM, which is triggered by Ca2+ elevation, is an SFK-dependent process, while CGE, triggered by either Ca2+ elevation or protein kinase C (PKC), is not. The possible involvement of SFKs in the signal transduction pathways that lead from the sperm-egg fusion site downstream of the Ca2+ release remains unclear.

Animals↗
PubMed2003

Oviposition behaviour of Gryon gallardoi (Hym.; Scelionidae) on eggs of Spartocera dentiventris (Hem.; Coreidae).

The oviposition behaviour of Gryon gallardoi (Hymenoptera; Scelionidae) on Spartocera dentiventris (Hemiptera; Coreidae) host eggs was investigated in the laboratory. Masses of 12 non-parasitized freshly laid (less than 24 h old) eggs were exposed to 2-5 days old mated females with previous oviposition experience (n = 10). Behaviour was observed for 2 h under the stereomicroscope. The eggs were Then kept individually at 25 degrees +/- 1 degree C/12 h photophase till hatching. The mean number of parasitized eggs was 7.8 +/- 0.81 (mean +/- SE). Five distinct kinds of behaviour were observed: drumming with antennae on the eggs, ovipositor insertion, egg marking, walking and resting. On average, ovipositor insertion was not followed by marking 4.3 +/- 0.76 times per female. In nearly all of these events, parasitism was unsuccessful. Walking and resting were observed less frequently than the other behaviours (1.6 +/- 0.56 and 2.1 +/- 0.48 times/female, respectively). Superparasitism occurred on average 3.6 +/- 0.88 times per egg mass, with 2.7 +/- 0.57 eggs being superparasitized. Among these, on average 87.4 +/- 5.37% led to successful development of an adult parasitoid. The average time spent on the each kind of oviposition behaviour was 1.5 +/- 0.57 min for drumming, 3.9 +/- 0.56 min for ovipositor insertion and 0.4 +/- 0.06 min for marking. There was no significant variation on the duration of each behaviour as the parasitoid progressed in parasitizing an egg mass. Ovipositor insertion almost always (87.58%) occurred in the longitudinal extremities of the egg. In average 31.1 +/- 7.21% of the individual emerging per egg mass were males, the larger proportion of males originating from the 2nd oviposition. The results show a range of oviposition behaviours common to the Scelionidae family. Egg marking behaviour was a good indicator of the effective oviposition by females. Superparasitism is only partially avoided, but its occurrence does not imply a failure of parasitoid emergence. The sex ratio is skewed towards females, and most males come from the first ovipositions.

Animals↗
PubMed1969

[Studies On Lactic Dehydrogenase Activities In Developmental Stages Of Fertilized Eggs Of Ascaris Lumbricoides]

The lactic dehydrogenase activities of Ascaris lumbricoides have been assayed according to the developmental course of the fertilized eggs compared with the unfertilized eggs. Experimental procedures were modified that of Wroblewski and La Due's method with use of diphosphopyridine nucleotide reduced form(DPNH). Sodium pyruvate and lactic dehydrogenase, the specific activities were expressed as DPNH unit per mg protein by method of Kornberg's. The experimental results are as follaws: 1. Lactic dehydrogenase activity in fertilized eggs of Ascaris are significantly increased from morula stage and its optimal pH is in 3.4 degrees. While any activities were not observed in unicell stage of fertilized eggs and unfertilized eggs. 2. Water soluble protein of fertilized eggs of Ascaris were varied in their amount during their developmental process. The amont of protein in tadpole stage eggs have increased to 1.3 times more than that of cleavage stage eggs. 3. However the amounts of water soluble protein in unfertilized eggs are revealed to one-third less than that of fertlized eggs. 4. The specific activity of lactic dehydrogenase in tadpole stage eggs are decreased to one third less than those of morula stage eggs during development, the stage is considered to be as a growth criteria in developmental process, as on this point the activity of aerobic cytochrome coxidase and cyclophorase begin to increase respectively.

Journal Article↗
PubMed1970

[Effects Of Irradiation With Cobalt 60 To The Development Of Ascaris Eggs In Stool]

This study was carried out in order to find out the valuable measure to kill the parasite eggs in night soil. The fresh eggs of Ascaris put into human stool were irradiated with Cobalt 60 of 200,000 to 1,000,000 rad and cultured in test tubes at 25-30 degrees C, washing with 2 % formalin solution every 24 hours. The continuous development of those eggs were observed under microscope and the proprotions of developed eggs were compared with those of control groups. The major result can be summarized as follows: 1)In general, The eggs in stool developed poorly than the eggs in saline. 2)If the eggs were irradiated with the larger dose of Cobalt 60, the proportion of developed eggs were reduced subsequently. 3)The eggs irradiated with the dose of 1,000,000 rad in saline developed in the proportion of 15.5 %, whereas irradiated with 200,000 rad 94 % developed in 4 weeks. 4)The 44.5 % of eggs in stool irradiated with 200,000 rad developed after 4 weeks, 30.5 % with 300,000 rad, 25 % with 500,000 rad and 3.5 % with 1,000,000 rad respectively. 5)The effective minimum dose of Cobalt 60 irradiation to kill the Ascaris eggs in stool was estimated 1,000,000 rad. Further examination will be required to observe the infectivity of irradiated Ascaris eggs to animals and to evaluate the effect from the standpoint of sanitary engineerings.

Journal Article↗
PubMed1985

[Number of intrauterine eggs in female Enterobius vermicularis by body length]

In order to correlate the number of eggs in female Enterobius vermicularis with their body length and to re-evaluate the number of eggs liberated by gravid females, a total of 203 worms were examined. Those females were removed from naturally infected orphans with mebendazole (100 mg) and had been fixed in 10 percent formalin(Cho et al., 1981). The decent ones which were selected under dissecting microscope were unbroken, neatly fixed females without contaminated eggs on their surface. The worms were measured by their body length, softened in 0.1N NaOH solution overnight, and teased by dissecting needles. And their number of shelled eggs was measured in a counting chamber made as described by Denham et al. (1971). The results were summarized as follows: The observed females, 4.10~9.90 mm long, began to have shelled eggs in uterus when body length was 5.50 mm or longer. The percentage of females with eggs in uterus was as follows by range of body length: 25 percent in 5.50~5.99 mm long, 53.3 percent in 6.00~6.49 mm long, 86.7 percent in 6.50~6.99 mm long, 95.2 percent in 7.00~7.49 mm long and 100 percent in 7.50 mm or longer. The mean and standard deviation of egg number were as follows by the length of females: 19+/-50 in 5.50~5.99 mm long, 734+/-1,597 in 6.00~6.49 mm long, 1,473+/-1,606 in 6.50-6.99 mm long, 1,530+/-2,055 in 7.00-7.49 mm long, 2,567+/-2,046 in 7.50-7.99 mm long, 5,598+/-2,470 in 8.00~8.49 mm long, 9,318+/-2,651 in 8.50~8.99 mm long, 10,678+/-2,892 in 9.00~9.49 mm long and 13,323+/-1,778 in 9.50~9.90 mm long. The numbers of uterine eggs showed greater individual variation when the female lengths were in range of 5.5~8.0 mm. When the female length was longer than 9.0 mm, the egg numbers were over 10,000 in majority, and showed lesser individual variations. Above results suggested that the egg production in female E. vermicularis began in 28-32 days after infection and that in early stages, the egg production varied by individual worms, but in gravid females longer than 9.0 mm at last deposited 10,000 to 16,000 eggs in their uterus with the least individual variations.

Journal Article↗
PubMed1987

Ahemeral light-dark cycles and egg production parameters of ring-necked pheasants (Phasianus colchicus).

The effects of two ahemeral light-dark (L:D) cycles on ring-necked pheasant egg production were investigated in this experiment. Three groups of 36 female and 12 male 10-month-old birds were exposed to control 24-hr (14L:10D), ahemeral 22-hr (14L:8D), or ahemeral 26-hr (14L:12D) L:D cycle. Average percent hen-day egg production (HDEP) was 63.8 for hens exposed to ahemeral 26-hr L:D cycle compared with 55.6% HDEP for the controls. Although this was not significant (P less than .05). It suggests a trend for pheasants exposed to ahemeral L:D cycles to improve egg production. Ahemeral L:D cycles did not significantly (P greater than .05) affect egg mass, shell-less eggs, cracked eggs, egg hatchability, and embryonic mortality. Shell quality, measured by specific gravity and shell thickness, was significantly (P less than or equal to .05) reduced for eggs obtained from hens exposed to ahemeral 22-hr L:D cycle. Fertility of eggs from hens kept under ahemeral 26-hr L:D cycle was significantly (P less than or equal to .05) improved compared with fertility of eggs from controls (89.3 vs. 78.4). Results of this research suggest that long ahemeral L:D cycles do play a role in the improvement of pheasant egg production and egg fertility.

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