Artificial Eggs Research Articles

Breeding of Crested Ibises Under Artificial Meteorological Conditions Factors

The crested ibis, also known as the Japanese crested ibis, belongs to the family Threskiornithidae in the order Ciconiiformes, with the scientific name Nipponia nippon Reichenbach. It is also known by other names such as red crane, red-faced ibis and Japanese phoenix. It is distributed in the Palearctic realm, occasionally migrating to the Oriental realm. It was once widely distributed from 20°30′ north latitude to 50°30′ north latitude and was considered an auspicious bird. The crested ibis is a critically endangered species worldwide. In the 1930s, in order to save this endangered species, ornithologists in China, regardless of the hardships, conducted surveys for many years and finally found the world's only two remaining wild groups of seven crested ibises. The world is paying great attention to the conservation of this species. Referring to numerous literature and data on crested ibises, combined with the process from discovery in the wild to artificial protection, artificial breeding in other places, artificial egg laying, and then hatching, we place crested ibises in an artificial elevated nylon mesh environment and implement natural pairing under artificial intervention. Combined with natural breeding and artificial hatching and rearing, we conduct active research on the physiology and growth development rules of crested ibises that abandon eggs, implement a rational nutritional formula, and actively promote the protection of this globally endangered species.

Comparing the Anti-candidal Effect of Egg White (Machine and Local) with Amphotericin B in Vitro

Introduction: The increase in the resistance of fungal species and the high side effects of antifungal drugs have led researchers to study and find new treatment methods against fungi. This study evaluated the anti-candidacy effects of local and artificial egg whites and compared them with amphotericin B. Materials and Methods: This study was conducted experimentally in May 2023 in the Microbiology Laboratory of Khalkhal Faculty of Medical Sciences. This research tested the antifungal effects of local and machine chicken egg whites and amphotericin B using the micro broth dilution and zone of inhibition method. In this experiment, Candida albicans species were placed in the vicinity of different concentrations of substances, and the minimum inhibitory concentration (MIC) and minimum fungicide concentration (MFC) of these substances on C. albicans were determined according to the guidelines of the Clinical and Laboratory Standards Institute. This study has been registered with the ethical code IR. IR.KHALUMS.REC.1401.019 in the Ethics Committee of Khalkhal Faculty of Medical Sciences. Results: Based on the results of the tests, the MIC of local and machine chicken egg whites on C. albicans was 25%, and their MFC was 50%. However, in these concentrations, no growth was observed in the presence of amphotericin B. Moreover, the MIC and MFC values of 25 µl of amphotericin B with 75 µl of local and machine egg whites were 3.125% and 6.25%, respectively. The zone of inhibition for C. albicans in the vicinity of local and machine chicken egg white and amphotericin B was 12, 11, and 16 mm, respectively. Conclusion: Local and machine chicken egg whites have antifungal properties against C. albicans.

Influence of temperature on embryonic development of Pontastacus leptodactylus freshwater crayfish, and characterization of growth and osmoregulation related genes

Narrow clawed crayfish, Pontastacus (Astacus) leptodactylus, represents an ecologically and economically valuable freshwater species. Despite the high importance of artificial breeding for conservation purpose and aquaculture potential, hatching protocols have not been developed so far in this species. Further, limited knowledge exists regarding the artificial egg incubation, the temperature effect on embryonic development, hatching synchronization and hatching rate. In the present study we investigated the temperature increase (from 17 oC to 22oC) effects in two different embryonic developmental stages of P. leptodactylus. Furthermore, two primer pairs for the Fibroblast Growth Factor Receptor 4 (FGFR4) gene cDNA amplification were successfully designed, characterising for the first time the FGFR4 gene in P. leptodactylus in relation to different developmental stages and temperatures. Apart from the FGFR4 gene, the Na+/K+-ATPase α-subunit expression was also explored. Both the FGFR4 and Na+/K+-ATPase α-subunit expression levels were higher in embryos closer to hatching. Egg incubation at 22oC for seven days led to significant increase of FGFR4 expression in embryos from earlier developmental stages. Nevertheless, temperature increase did not affect FGFR4 expression in eggs from latter developmental stages and Na+/K+-ATPase α-subunit expression in all developmental stages. Temperature increase represents therefore probably a promising strategy for accelerating hatching in freshwater crayfish particularly in early developmental stages. Specifically, our results indicate that FGFR4 expression increased in embryonic stages closer to hatching and that temperature influences significantly its expression in embryos from earlier developmental stages. Overall, these findings can provide a better understanding of artificial egg incubation of P. leptodactylus, and therefore can be employed for the effective management of this species, both for economic and biodiversity retention reasons.

Aedes (Stegomyia) albopictus in rural areas in Brazil: First Record in the State of Ceara

Background: This work aims to describe the finding of Aedes albopictus in an intra- and peridomiciliary area of the rural area in the south-central region of Ceará and discuss the need for entomological surveillance of this species in the country. Method: Through traps installed in an intra- and peridomiciliary environment and artificial breeding grounds, eggs and larvae of Ae. albopictus were captured in a rural area of the state of Ceará. Results: This is the first record of Ae. albopictus in the south-central region of the state of Ceará. We collected 418 eggs and 252 larvae from Ae. albopictus, being 85% of eggs in the peridomiciliary area, on average 29.41 (± 37.34) eggs per trap. As for larvae, about 70% of them were caught on tires. Only 42 larvae (14,2%) belonged to species other than the genus Aedes, found in tires and an engine. Conclusion: The presence of Ae. albopictus in rural areas close to urban areas warns of the need to effectively insert this vector as a surveillance target, carry out an active search, monitor its presence in municipalities, and investigate its involvement with outbreaks in or near areas where they are present.

Axenic mass culture of soil-borne nematodes using artificial egg yolk medium

ABSTRACT The amenability to axenic culture in vitro on solid medium including MacConkey, soybean casein, nutrient broth and egg yolk medium of Oscheius tipulae, Caenorhabditis elegans, Acrobeloides tricornis, Acrobeloides bodenheimeri and Teratorhabditis synpapillata were tested using Petri dishes. These nematodes were incapable of growing in MacConkey, soybean casein and nutrient broth, except for C. elegans which was able to multiply in soybean casein medium. While all nematodes used were successfully mass cultured using egg yolk medium at 25°C, results revealed that the highest yield of nematodes was observed with O. tipulae (TC2 and OC2), attaining 176 and 150 k nematodes per plate, respectively, after 10 days post-inoculation. In contrast, the lowest yield was recorded for T. synpapillata. The medium was optimised using different egg yolk concentrations (0, 5, 10, 20 and 40 g/L) and was tested for four nematode species O. tipulae, A. bodenheimeri, A. tricornis and T. synpapillata. The results showed that the egg yolk concentrations and the kinetic of nematode multiplication were positively correlated. Additionally, egg yolk liquid medium was applied to the mass culture of nematodes. Oscheius tipulae, A. bodenheimeri and A. tricornis were capable of reproduction in Petri dishes containing egg yolk liquid medium, at 25°C. Contrarily, T. synpapillata was unable to grow on the same liquid medium. The highest nematode yields of O. tipulae and A. bodenheimeri were attained 10,266 and 4110 nematodes in average, respectively, at 16 days post-inoculation. The maximum multiplication of A. tricornis was recorded at 20 days post-inoculation with 8430 nematodes.

Social deprivation in maternal mouthbrooders Tropheus sp. “Caramba” (Teleostei: Cichlidae) decreases the success rate of reproduction and survival rate of fish fry

Early offspring separation from mothers causes social deprivation. Mouthbrooding, when eggs and fry are incubated in the buccal cavity of the parent, is one of the reproductive strategies in fish. The mother is the incubating parent in African lake cichlids from the genus Tropheus. Many of these are produced in captivity and some producers use artificial incubators in which eggs are incubated separately from the mother. We hypothesized that this practice may dramatically modify the reproduction rate of fish individuals produced by the method of artificial incubation. The long-term experiment focused on Tropheus sp. “Caramba” had been carried out for 10 years when maternally incubated and separated individuals were compared. We found a negative effect of artificial egg and offspring incubation out of the mother’s buccal cavity. The deprived females laid the same number of eggs as maternally incubated females, but most eggs were lost during the incubation. Moreover, the reproduction frequency was significantly lower in deprived females in comparison with those maternally incubated. This study should be perceived as preliminary. For this reason and with respect to welfare principles, we strongly recommend similarly designed experiments focused on other potentially sensitive fish mouthbrooders. Once the syndrome would be confirmed, we recommend avoiding artificial incubation of mouthbrooding fish in general.

Policing is more effective against eggs of non‐natal versus natal workers at early colony stages in a bumblebee

AbstractEusocial insect colonies are vulnerable to exploitation by egg‐laying workers arising either as natal reproductive workers or as non‐natal reproductive ‘drifting’ workers (intraspecific social parasites). Worker egg‐laying is potentially costly to the colony, but queens and workers can counter its costs via egg eating (queen or worker policing). Bumblebee colonies exhibit egg laying by both natal and non‐natal workers: natal workers collectively lay more eggs but do so only after a specific point in the colony cycle, the ‘competition point’, whereas non‐natal workers potentially lay eggs throughout the colony cycle. These features create a special opportunity to investigate whether policing of worker‐laid eggs is context‐dependent (i.e. depends on worker origin of eggs and/or colony stage). We introduced artificial egg cells containing eggs laid by either natal or non‐natal workers into colonies of the bumblebee Bombus terrestris both before and after their competition points and observed the fate of introduced egg cells and eggs. In both colony stages, the majority of introduced egg cells and eggs were policed, demonstrating that policing was not activated only after the competition point. However, in the pre‐competition point stage alone, a smaller proportion of non‐natal workers' eggs (15%) remained after 20 h compared to the proportion of natal workers' eggs remaining (24%). More effective policing of non‐natal workers' eggs early in the colony cycle potentially represents an adaptive, context‐dependent response to the stage in the cycle when all worker‐laid eggs are normally unrelated to the natal colony.

Settling and transport properties of grass carp and silver carp eggs in the water-hardened phase: Implications for resource protection and invasion control during early life period

Grass carp and silver carp eggs have no swimming ability in the water-hardened phase and need to drift for tens or even hundreds of hours before complete incubation. A full comprehensive understanding of the settling and transport properties of eggs is crucial for the resource protection and invasion control of Four Major Chinese Carps (FMCCs) during their early life stages. Artificial eggs have been used extensively in previous field and flume experiments; however, our understanding of the settling and transport properties of real eggs in the water-hardened phase remains limited. In the present study, a series of column and flume experiments were conducted in stagnant and moving water, respectively. In light of the differences in settling characteristics, caution should be exercised when applying research results obtained from artificial eggs having the closest diameter and specific gravity as real eggs. Compared with grass carp and silver carp eggs in the water-hardening phase, egg diameters in the water-hardened phase were 36% and 33% greater, respectively, and egg hydrostatic settling velocities were 31% and 40% lower, respectively. Significant interspecific differences between the two species exist in terms of egg size and hydrostatic settling velocity. Based on linear mixed effects analysis of dominant transport trajectories and regression analysis between suspending rate and flow velocity, 0.30 m/s can be considered as critical drifting velocity in uniform flow. Adaptive management schemes are discussed to promote resource protection and invasion control of FMCCs during the early life stages. The results of the present study enhance our understanding of drifting egg movement and provide insights that could facilitate the comprehensive management of FMCCs.

SMART EGG INCUBATOR BASED ON MICROCONTROLLER: A REVIEW

Artificial egg incubators are devices that are used to incubate and hatch eggs by maintaining the necessary conditions for fetal development within the egg. Any egg that is being incubated requires a great deal of attention and temperature control. This is accomplished by the use of a temperature control device that runs on electricity. Incubator temperatures are often kept between (98 and 100) degrees Fahrenheit. Even yet, only 78 to 85% of eggs will hatch. To increase the hatchability of the incubator unit, many recommendations are made. Moisture content is another essential consideration that should be stated in the range of 60% to 80%. While hatching the eggs in an incubator unit, there are a number of important aspects to consider. However, the most crucial component is to keep the temperature range within acceptable limits. In this respect, there are many research papers accessible. In general, this article reviewed latest 21 works in literature and provided a complete analysis of a number of ways to control temperature, humidity, and eggs rotation based on microcontrollers to provide a solution to the poultry industry in developing nations. A comparative analysis for recent incubator design approaches in literature is presented by this study including the works of five recent researchers such as, brief discussion of their objectives, problems they try to fix, methodology, preliminary results, and the decision made on each work. Finally, based on reviewing analysis, there is a gap that has not been covered, that is, the remote control and monitoring of the incubator using Internet of Things (IoTs) technology. This function is essential for the incubator to be accessible to boost the product and reduce the malfunction causing product and time losses.

Can Artificial Intelligence Predict Good Eggs From Bad? Comparing Oocyte Assessment Tool Violet To Current Egg Freezing Predictors

BACKGROUND: Future Fertility’s Violet is an artificial intelligence image analysis egg assessment tool for patients seeking elective oocyte preservation. The technology is used to identify the relative viability of mature eggs to tailor a personalized treatment plan for each patient. The software detects patterns in oocytes in order to better understand egg quality. It may be particularly impactful for older patients who are known to have problems related to egg quality, especially given the fact that they may have less opportunities to undergo multiple cycles. While we currently have methods for assessing sperm quality and embryo quality, there are very limited guidelines for determining successful oocytes. Violet is currently the only objective assessment tool for predicting egg quality. Current research suggests Violet is superior to trained embryologists by more than 20%, with 100% reproducibility . More data is needed to assess the viability of Violet to better assess the value it provides in improving IVF outcomes. OBJECTIVE: We sought to compare predictions of live birth rate between Violet and a currently utilized egg freezing predictor, which takes into account age and number of mature oocytes. MATERIALS & METHODS: A retrospective chart review was performed at a private multi-site infertility center from March 2020 to April 2022. All patients undergoing elective egg vitrification who opted to get oocyte assessment results from Violet were included, for a total of 154 patients. Patients under the age of 24 or over the age of 44 were excluded as the calculator is not recommended in those age groups. All patients underwent controlled ovarian stimulation and subsequent retrieval and mature oocyte vitrification. Likelihood of one live birth was given as a percentage by the Violet report. These results were compared to the Brigham & Women’s Hospital Egg Freezing Counseling Tool (BWH EGCT) calculator per MDCalc. An unpaired t-test was performed to compare the mean percentages. Given differences in egg quality with relation to age, we also sought to determine if there was a difference in results by age (age groups: 27-32, 33-38, and 39-44 years old). RESULTS: The probability of one live birth was assessed using Violet as well as the BWH EGCT for 154 patients. Mean AMH of patients included was 2.42. Mean age at retrieval was 36, with a range of 27-44. The mean likelihood of one live birth rate using Violet as an assessment tool was 47.60%, while the conventional method gave a mean likelihood of one live birth of 49.14% (p=0.6079). There was no significant difference in predictions by Violet versus the conventional method by age, though the results did approach signficance (p=.12 for 27-32, p=.24 for 33-38, and p=.13 for 39-44). CONCLUSIONS: This is the largest study to our knowledge assessing the viability of Violet compared to conventional methods for assessing egg quality. Our results suggest there is no significant difference between the AI oocyte assessment tool Violet and conventional methods for prediction using age and number of mature oocytes. Additionally, there is no signficant difference when comparing results by age group. This suggests that Violet is able to individually visually assess oocytes for quality and likelihood of success. Violet provides a non-invasive approach and a comprehensive breakdown of the quality of each oocyte. Though these results suggest Violet is similar to existing predictors, it adds value by determining the individual quality of each oocyte. This allows for stratification that can guide fertility decision-making. A limitation of the study is the fairly low number of patients given this is a new technology. As more patients utilize the Violet assessment tool, there will be greater numbers of oocytes that undergo thaw, insemination, and transfer. This will provider greater data regarding fertilization, blastocyst development, and ultimately live birth rate. Though this technology is still in its relative infancy, there is an exciting future ahead for artificial intelligence in assessing oocyte quality and predicting IVF success.

ASPECTOS BIOLÓGICOS E CAPACIDADE PREDATÓRIA DE Doru luteipes QUANDO ALIMENTADA COM Spodoptera frugiperda

ABSTRACT Biological aspects and predatory capacity of Doru luteipes was assessed as a function of predation on Spodoptera frugiperda. The experiment was conducted under laboratory conditions of mean temperature of 25 ± 1 °C, relative humidity of 70 ± 10%, and 12:12 h (Light: Dark) photoperiod. To evaluate the biological parameters of D. luteipes, artificial diet, eggs and caterpillar (1st, 2nd, 3rd, 4th, 5th or 6th instars) of S. frugiperda were supplied. The completely randomized statistical design was used, with 10 replicates for each treatment. The nymphs (1st, 2nd and 3rd instars) and adult males and females of D. luteipes were individualized in Petri dish (9 cm diameter), with artificial diet as standard food (control). Nymphs of the 1st and 3rd instars of the predator lasted 4.5 and 6.9, days respectively, but they perished. The survival of D. luteipes is high, but there was variation when consuming the different instars of the caterpillar of S. frugiperda. Adults of D. luteipes did not consume caterpillars of the 4th, 5th and 6th instars of the prey. There was a significant difference for the feeding of D. luteipes with artificial diet, eggs and caterpillar of S. frugiperda with respect to the parameters number of eggs and preoviposition. Higher consumption of male and female D. luteipes occurs when they are fed with prey eggs.

Facts About Artificial Eggs

Facts About Artificial Eggs

Nesting success of Sharpe’s Longclaw (Macronyx sharpei Jackson, 1904) around the grasslands of lake Ol’bolossat Nyandarua, Kenya

Sharpe’s Longclaw Macronyx sharpei is an endangered Kenyan endemic bird restricted to high-altitude grasslands with long tussocks. The species occurs on the grasslands surrounding Lake Ol’Bolossat in Nyandarua, Kenya, an area that is globally recognized as an Important Bird and Biodiversity Area. The grasslands receive little conservation measures, which have led to the decline in the population density of Sharpe’s Longclaw. Nesting success in birds is crucial for their population growth. The daily survival rate for natural nests of Sharpe’s Longclaw in the grasslands of Lake Ol’Bolossat had not been systematically assessed prior to this study. Natural nests were actively searched during the breeding seasons of March–May 2016, while artificial nests were constructed using dry grass containing artificial eggs made of cream modeling clay. Natural nests had a higher daily nest survival percentage than artificial nests. The highest daily nest survival rate was 40% and the lowest 0.01%. Predators, livestock grazing and fires greatly reduced the survival of nestlings. We recommend intensive ecological management of the high-altitude grasslands of Lake Ol’Bolossat.

Nest predation pressure on Chinese Bulbuls decreases along the urbanization gradient in Hangzhou, China

Nest predation is an essential factor affecting bird population density, reproductive ecology and life cycle. However, there are still contradictory results about how nest predation pressure changes with urbanization. One of the reasons for the controversy is that previous studies often use artificial nests to investigate nest predation, but the result of artificial nests is often biased and contrary to that of natural nests. Therefore, it is important to perform nest predation experiments simultaneously with both natural and artificial nests. In this study, we examined the change of nest predation pressure on the Chinese Bulbul (Pycnonotus sinensis) along the urbanization gradient in Hangzhou, China. We detected 148 natural nests of Chinese Bulbuls and continuously monitored them in two continuous breeding seasons from 2012 to 2013. After the breeding season, we placed artificial eggs in natural nests of Chinese Bulbuls to investigate the changes in nest predation pressure and used infrared cameras to record the predators. We then calculated the urbanization synthetic index (USI) as the measure of the degree of urbanization and examined its relationship with nest predation pressure. We found that no matter whether natural nests or artificial eggs were used, the nest predation pressure always decreased significantly with the degree of urbanization. The average height of shrubs within 10 ​m of the nest differed significantly between the predated and unpredated nests, which also affected the risk of nest predation. Our study highlights the importance of using natural and artificial nests simultaneously to conduct nest predation experiments, which can reduce the bias or errors caused by only using artificial nests. We also recommend the use of infrared cameras in future nest predation studies, which has obvious advantages in monitoring and identifying potential predators.

Investigating how different classes of nest predators respond to the playback of the begging calls of nestling birds

Begging brings benefits and costs for nestling birds: it can indicate their needs to their parents, but it can also be a cue used by predators to find the nest. The costs, like many variables related to nest predation, can be specific to what kinds of predators are present and their auditory capabilities. These costs and benefits could also be affected by human noise, as noise could disrupt communication to parents and eavesdropping by predators, although human-produced noise might be easily ignored if predators can hear high-frequency components of the begging. We studied nest predation on a generalist bird, the Red-whiskered Bulbul (Pycnonotus jocosus), in a tropical forest in which there are many kinds of nest predators, including birds, mammals and reptiles. In 20 natural nests in which artificial eggs were placed, and subsequently in 140 artificial nests, we broadcast recordings of begging nestlings, with and without traffic noise, at two volume levels. We hypothesized that playback would increase predation relative to a silent control, and that mixing in traffic noise with the begging would decrease predation, as the begging signal was masked. However, we hypothesized that some predators, particularly small mammals with sensitive high-frequency hearing, might ignore the traffic noise. We found that predation was lowest for the control treatment, and lower for treatments mixed with traffic noise than for those without it. Small mammals, however, showed an unexpected pattern, displaying less nest predation in the treatments with traffic noise. Our results demonstrate the human-associated noise can disturb nest predators and influence which kinds of predators use begging to locate nests.

Active Electronic Egg for Breeding of Endangered Birds

This work presents a prototype of an artificial egg for use in breeding centres for endangered birds. These eggs replace the inert artificial eggs that are given to the birds while the natural egg is incubated in the laboratory. When the chick hatches, it is given to the parents to continue breeding. This first prototype of the active egg is designed for the bearded vulture (Gypaetus barbatus), simulating the sounds and movements of the chick inside, and with the same appearance, size and weight as a natural one. The movements and sounds of the active artificial egg are made at the request of its caregiver and under his supervision and control in real time via a wireless connection. The active artificial egg has battery-powered circuitry inside that allows it to maintain wireless communication between the caregiver and the egg, because the egg must not perform autonomous physical actions at any time. This prototype has been tested for three seasons on a foster male and a natural couple of birds with good results because the birds have not rejected the prototype and have shown exactly the same behaviour exhibited when incubating a natural egg. The electronic system has among other circuits a microcontroller, a small motor to produce vibrations that simulate the movement of the chick and an mp3 player for the reproduction of sounds previously recorded on a microSD card. A low power consumption system has been designed to increase the autonomy of the device.

Internet of Things Enabled Smart Animal Farm Prototype

Livestock plays very important economic, social and cultural roles in the well being of rural communities across the world. Quality environmental conditions, automation and monitoring are the key necessities of running a good and profitable livestock farm. Air quality, temperature of the surroundings and humidity play a major role while deciding the fan speeds of the exhaust System used in all aspects of livestock farming. Another important part of livestock production is increasing incubation speeds of eggs by performing artificial incubation. It is a requirement to maintain the temperature at a constant value in this system. This paper describes two mutually exclusive Fuzzy Logic algorithm-based systems to automate the exhaust system and an artificial egg incubator. The other important part of a livestock farm is production of milk and milk products. It is required to monitor the health of cows by overseeing their activities at any point of time. This can be done by determining and monitoring the activities performed by the cow. This paper describes a simple Deep Learning Model to classify the activities of a cow broadly as standing, walking or grazing. The Exhaust and the Incubator system are controlled and monitored using Internet of Things (IOT) System using a native web application developed using the Flask framework.

A Study of the Impact and Challenges Faced using Artificial Egg Incubation

A Study of the Impact and Challenges Faced using Artificial Egg Incubation

Discrimination and ejection of eggs and nestlings by the fan-tailed gerygone from New Caledonia.

Nestling rejection is a rare type of host defense against brood parasitism compared with egg rejection. Theoretically, host defenses at both egg and nestling stages could be based on similar underlying discrimination mechanisms but, due to the rarity of nestling rejector hosts, few studies have actually tested this hypothesis. We investigated egg and nestling discrimination by the fan-tailed gerygone Gerygone flavolateralis, a host that seemingly accepts nonmimetic eggs of its parasite, the shining bronze-cuckoo Chalcites lucidus, but ejects mimetic parasite nestlings. We introduced artificial eggs or nestlings and foreign gerygone nestlings in gerygone nests and compared begging calls of parasite and host nestlings. We found that the gerygone ejected artificial eggs only if their size was smaller than the parasite or host eggs. Ejection of artificial nestlings did not depend on whether their color matched that of the brood. The frequency of ejection increased during the course of the breeding season mirroring the increase in ejection frequency of parasite nestlings by the host. Cross-fostered gerygone nestlings were frequently ejected when lacking natal down and when introduced in the nest before hatching of the foster brood, but only occasionally when they did not match the color of the foster brood. Begging calls differed significantly between parasite and host nestlings throughout the nestling period. Our results suggest that the fan-tailed gerygone accepts eggs within the size range of gerygone and cuckoo eggs and that nestling discrimination is based on auditory and visual cues other than skin color. This highlights the importance of using a combined approach to study discrimination mechanisms of hosts.

O-039 Mitochondrial ATP generation in mammalian eggs and Ca2+ signaling

Abstract text In metaphase II arrested mammalian oocytes (eggs) and cleavage stage embryos the mitochondria are responsible for nearly all ATP production because glycolysis is inactivated. Luciferase assays show that ATP levels in eggs are strictly dependent upon pyruvate and fatty acid oxidation. The level of ATP in eggs appears to be maximal in conventional medium because the addition of extra mitochondrial substrates to eggs does not increase cytosolic ATP. The only clear elevation of ATP is seen at fertilization and is associated with sperm induced Ca2+ oscillations. Our recent findings suggest that the level of ATP modulates events at fertilization. At fertilization, the egg is activated by sperm derived PLCzeta which triggers a series of Ca2+ oscillations, with each Ca2+ release event causes by inositol trisphosphate (InsP3). Previous studies have shown that mouse eggs are more sensitive to PLCzeta, and generate higher frequency Ca2+ oscillations, than human eggs. Mouse eggs also generate Ca2+ oscillations and activate in response to Sr2+ that directly stimulates InsP3 receptors. In contrast, human eggs that contain the same type of InsP3 receptors do not generate Ca2+ oscillations in response to Sr2+. The difference in sensitivity of Ca2+ release between species can be explained by the fact that mouse eggs are about ten times more sensitive to InsP3 than human eggs. The reason for this difference appears to be due to ATP. The ATP level in unfertilized mouse eggs is about twice that in human eggs. Furthermore, the ability of mouse eggs to Sr2+ medium can be abolished by removing the mitochondrial substrate pyruvate, which reduces the ATP level. Adding back pyruvate to such eggs restores ATP levels promotes Sr2+ induced Ca2+ levels in mouse eggs. These data suggest that the level of ATP, possibly as ATP4-, modulates the sensitivity of the InsP3 receptor and the ability of eggs to generate Ca2+ oscillations. The level of cytosolic ATP may represent a significant ‘egg factor’ in determining the success of fertilization in humans. Enhancing mitochondrial ATP production could be useful in improving activation and embryo development after fertilization, or after artificial egg activation.