Avian Yolk Research Articles

Natural cross-reactive anti-SARS-CoV-2 antibodies in avian egg yolk.

Since the beginning of the 21st century, the Coronaviridiae family has caused several life-threatening outbreaks in the world. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is the cause of the latest Coronaviridiae-related outbreak, is still a major health issue worldwide. Prevention, diagnosis, and therapeutic actions are the most important strategies to mitigate the spread of the COVID-19 pandemic. Among therapeutics, specific antibodies play a crucial role in controlling the symptoms of patients and preventing others from becoming infected. Here, we have introduced the avian egg yolk as a natural source of cross-reactive anti-SARS-CoV-2 immunoglobulin Y. ELISA, dot blot and western blot were used to identify natural anti-SARS-CoV-2 IgY in the egg yolk of different species of birds. Also, bioinformatics analysis was performed to investigate the possible causes of the presence of these natural antibodies in the egg yolks. The results of blotting and ELISA assays demonstrated that the egg yolk-derived antibodies could identify and bind to the different subunits of SARS-CoV-2. Substantial concentrations of neutralizing antibodies against SARS-CoV-2 were also detected in the egg yolk. In addition, bioinformatics analysis showed structural similarities between the components of infectious bronchitis virus, SARS-CoV-2, and other members of the Coronaviridiae family. It seems that egg yolk can be used as a natural, inexpensive, and accessible source of anti-SARS-CoV-2 antibodies. Diverse diagnostic and therapeutic potentials for avian egg yolk-derived anti-SARS-CoV-2 antibodies are imagined.

Scaling Relationships among the Mass of Eggshell, Albumen, and Yolk in Six Precocial Birds.

The proportions in the size of the avian egg albumen, yolk, and shell are crucial for understanding bird survival and reproductive success because their relationships with volume and surface area can affect ecological and life history strategies. Prior studies have focused on the relationship between the albumen and the yolk, but little is known about the scaling relationship between eggshell mass and shape and the mass of the albumen and the yolk. Toward this end, 691 eggs of six precocial species were examined, and their 2-D egg profiles were photographed and digitized. The explicit Preston equation, which assumes bilateral symmetrical geometry, was used to fit the 2-D egg profiles and to calculate surface areas and volumes based on the hypothesis that eggs can be treated as solids of profile revolution. The scaling relationships of eggshell mass (Ms), albumen mass (Ma), and yolk mass (My), as well as the surface area (S), volume (V), and total mass (Mt) were determined. The explicit Preston equation was validated in describing the 2-D egg profiles. The scaling exponents of Ma vs. Ms, My vs. Ms, and My vs. Ma were smaller than unity, indicating that increases in Ma and My fail to keep pace with increases in Ms, and that increases in My fail to keep pace with increases in Ma. Therefore, increases in unit nutrient contents (i.e., the yolk) involve disproportionately larger increases in eggshell mass and disproportionately larger increases in albumen mass. The data also revealed a 2/3-power scaling relationship between S and V for each species, that is, the simple Euclidean geometry is obeyed. These findings help to inform our understanding of avian egg construction and reveal evolutionary interspecific trends in the scaling of egg shape, volume, mass, and mass allocation.

Early conversion of maternal androgens affects the embryo already in the first week of development.

Maternal androgen exposure has potent effects on offspring development. As substantial levels of maternal androgens are deposited in avian egg yolks, avian eggs are frequently used to study maternal effects, with a strong focus on post-natal development. However, the underlying pathways are largely unknown. Since the hormones are taken up during the embryonic phase, and these are rapidly metabolized by avian embryos into metabolites such as etiocholanolone, we studied the effects of yolk androgens (testosterone and androstenedione) and their metabolite etiocholanolone during the first few days of embryonic development. As embryonic heart rate is often used as an indicator of embryonic development, we measured the heart rate from day 3 to day 6 of incubation by using a shell-less culture technique in rock pigeon eggs (Columba livia). Increased androgen exposure increased heart rate, and increased etiocholanolone mimicked this effect, albeit in a small sample size. This indicates that exposure to maternal androgens increases embryonic overall metabolism which may account for the developmental outcomes found in previous studies such as increased growth. Moreover, etiocholanolone is likely to be an important metabolite in a non-genomic pathway underlying the androgen-mediated maternal effect.

Chicken IgY reduces the risk of Pseudomonas aeruginosa urinary tract infections in a murine model.

IntroductionUrinary tract infections (UTIs) with Pseudomonas aeruginosa are a severe problem in disposed patients in modern healthcare. Pseudomonas aeruginosa establishes recalcitrant biofilm infections and can develop antibiotic resistance. Gargling with avian egg yolk anti-Pseudomonas antibodies (IgY) has shown clinical effect in preventing onset of chronic P. aeruginosa lung infections in patients with cystic fibrosis (CF). Therefore, we speculated whether passive intravesically administered IgY immunotherapy could be a novel strategy against P. aeruginosa UTIs.AimTo evaluate if prophylactic repurposing of anti-Pseudomonas IgY can prevent UTIs with P. aeruginosa in a UTI mouse model.Materials and methodsIn vitro, P. aeruginosa (PAO1 and PAO3) was mixed with increasing concentrations of specific anti-Pseudomonas IgY (sIgY) or non-specific control IgY (cIgY) and/or freshly isolated human neutrophils. Bacterial growth was evaluated by the optical density at 600 nm. In vivo, via a temporary transurethral catheter, 10-week-old female Balb/c mice were intravesically infected with 50 ml of a bacterial suspension and sIgY, cIgY, or isotonic NaCl. IgY and NaCl were either co-instilled with the bacteria, or instilled prophylactically, 30 min prior to infection. The animals were euthanized 20 h after infection. Vesical bacteriology was quantified, and cytokine expression in the bladder homogenate was measured by multiplex cytokine assay.ResultsIn vitro, sIgY concentrations above 2.5% reduced bacterial growth in a dose-dependent manner. In vivo, a UTI lasting for minimum 7 days was established by installing 5 × 106 colony-forming units (CFU) of P. aeruginosa PAO1. sIgY reduced vesical bacterial load if co-installed with P. aeruginosa PAO1. Prophylactic sIgY and cIgY reduced bacterial load when compared to isotonic NaCl. CXCL2 and G-CSF were both increased in infected bladders compared to non-infected controls which had non-detectable levels. Co-installation of sIgY and bacteria nearly completely inhibited the inflammatory response. However, the cytokine levels in the bladder did not change after prophylactic administration of sIgY or cIgY.ConclusionProphylactic sIgY significantly reduces the amount of bacteria in the bladder in a mouse model of P. aeruginosa cystitis and may serve as a novel non-antibiotic strategy in preventing P. aeruginosa UTIs.

Protective Effects of Different Egg Yolk Sources on Cryopreservation of Scaly Carp (Cyprinus carpio) Sperm

Egg yolk is one of the most widely used cryoprotective components of extenders, especially for the cryopreservation of mammalian species’ sperm cells. However, there is a lack of information regarding their efficacy in cryopreservation of fish sperm cells. Thus, the objective of this experiment was to compare the effectiveness of egg yolk from different avian species (duck, goose, and chicken) on post-thaw quality and fertilization ability of scaly carp (Cyprinus carpio) semen following cryopreservation. Sperm samples diluted with the sucrose-based extender at the ratio of 1:10 were supplemented with 10, 15, and 20% ratios of different avian egg yolks. In the control group, sperm samples were diluted with the sucrose-based extender, without egg yolk. Following dilution, sperm samples were equilibrated at +4⁰C for 10 min and aspirated into 0.25-ml straws. Then, sperm samples were frozen 3 cm above the liquid nitrogen (LN2) surface and plunged directly into the LN2. The frozen sperm cells were thawed in a water bath at 35 ⁰C for 30 s and fertilization was carried out using a 1x105 spermatozoa/egg ratio. Based on the results, supplementation of sperm cells with 20 % duck egg yolk in a sucrose-based extender exhibited the best post-thaw progressive motility (67.8 ±1.24%), progressive motility duration (32.6 ±1.45 s), viability (82.4 ±1.36%), and fertility (92.6 ±1.28%) compared to the control group (P<0.05). The results of the experiment showed that duck egg yolk could be used as an alternative instead of chicken egg yolk in a sucrose-based extender for the cryopreservation of scaly carp sperm.

Exogenous testosterone administration decreases rates of ovarian follicle growth in domestic chickens

Avian egg yolks provide critical nutrients and energy reserves for a growing embryo. Once a follicle is selected into the ovulatory hierarchy, rings of yolk precursors are deposited daily until the yolk is large enough to ovulate. The composition of hen egg yolk and the mechanisms responsible for deposition in the ovarian follicle are well-studied. However, the factors that affect the rate of yolk deposition, and the number of days it takes for follicles to grow to the optimal size for ovulation, are less well-known. Social interactions appear to impact the rate of yolk deposition in many avian species and testosterone is a key hormone involved in regulating those interactions. Therefore, we hypothesized that testosterone would influence the rate of follicle growth. We tested the influences of exogenous testosterone treatment by rubbing either testosterone propionate cream (1.25 %) or a control cream to hen combs daily for 7 days to increase plasma testosterone concentrations. We then collected eggs and measured egg and yolk weight, yolk diameters, and stained and counted the number of concentric rings in each yolk. Testosterone-treated hens laid fewer eggs and grew their yolks more slowly than control hens. Testosterone also caused an increase in yolk weight but not yolk diameter. These results indicate that testosterone may play a role in the rate of yolk deposition in birds.

The Use of Avian Yolk Antibodies in the Inactivation of Highly Toxic Components of Biological Weapons and Especially Dangerous Infections

Currently, Western pharmaceutical companies have mastered the production of licensed drugs based on transovarial chicken specific antibodies (IgY antibodies) intended for the treatment and prevention of infections caused by Helicobacter pylori, influenza virus and other pathogens. Of particular interest is the possibility of using IgY antibodies as an inexpensive specific antidote for emergency specific prevention of infections caused by pathogens of dangerous and especially dangerous infections. The purpose of this work is to summarize the results of studies that have shown a high therapeutic potential of transovarial specific immunoglobulins in the treatment and prevention of dangerous viral, bacterial infections and injuries by biological toxins – potential agents of biological weapons (BW). The advantage of using IgY technologies for passive immunization is a non-invasive method for obtaining antibodies, as well as a large amount of them – 20–30 g of immunoglobulins, which can be obtained from one laying hen per year. An important advantage of IgY over immunoglobulins derived from mammalian serum is that they do not interact with complement components, nor with rheumatoid factor, nor with Fc receptors of mammalian immunocompetent cells, which significantly reduces the manifestation of adverse reactions, in particular, antibody-dependent enhancement of infection (ADE). Experiments carried out in vivo and in vitro showed a high activity of IgY antibodies in suppressing the damaging effect of pathogens of especially dangerous infections and biological toxins. It is shown in the article, that the replacement of mammalian IgG with avian transovarial IgY allows obtaining commercially significant amounts of thermostable specific antibodies that do not cause ADE, and expands the possibilities of methods for specific prevention and treatment of lesions caused by viruses, bacteria, and toxins – potential agents of biological weapons

Yolk corticosterone and progesterone levels in Greater Rhea (Rhea americana) eggs vary in a changing social environment.

Maternal hormones in avian egg yolks may signal and prepare offspring for the prevailing conditions. However, this adjustment requires some degree of flexibility in regulating yolk hormone deposition. The Greater Rhea (Rhea americana) has a particular mating system that combines mixed polygyny and polyandry, communal nesting, and exclusive paternal care of chicks. In this species, we previously found that yolk hormone deposition varies among eggs of different captive populations and could influence chicks' physiology and behavior. However, it is still unknown whether females can modify yolk hormone deposition in a changing social environment. Using a captive population of Greater Rheas, in this study, we quantified yolk hormone levels before and after a reduction in the number of females present in the population. We found that females deposited on average higher yolk corticosterone and lower yolk progesterone after the change in their social environment. Since corticosterone deposited into the yolk comes exclusively from the female's plasma, our results suggest that females had, on average, higher plasma corticosterone levels. The change in the number of females may increase the events of male-male competitions, courtships, and matings, leading to an increase of corticosterone in the females' plasma and then into their eggs. Since we previously found that higher yolk corticosterone and lower yolk progesterone were associated with the production of chicks that have an attenuated stress response, the present study results suggest that yolk hormone deposition is mediated by flexible mechanisms that could adjust development to the prevailing conditions.

Evaluation of Fresh and Chilled Sahel bucks Semen Extended with two different Avian egg yolks (Chicken and Guinea fowl) based extenders preserved at 5 °c in Maiduguri, Nigeria

Evaluation of Fresh and Chilled Sahel bucks Semen Extended with two different Avian egg yolks (Chicken and Guinea fowl) based extenders preserved at 5 °c in Maiduguri, Nigeria

Comparative Study of Using Four Types of Avian Egg Yolk for Epididymal Sperms Chilled Storage in Awassi Rams (Ovis aries)

The objective of current study was to use four types of egg yolks for ram epididymal sperms The objective of current experiment was to study the effect of different avian egg yolks (EYs) on rams epididymal sperms stored at 4 oC. Sixteen pairs of testes (n=32) were mature Awassi rams of about 1-4 years, slaughtered at a Al-Sadoon abattoir/ Mosul city were collected. The spermatozoa were collected from tail of epididymis by cutting and squeezing, after that a total of 0.5 ml of spermatozoa volume was diluted by using sodium citrate 2.9% and the volume completed to 1 ml, then the sample divided into four aliquots (0.25 ml for each one). The extender consisted of egg yolk (EY) 10% of four avian types (chicken, quail, duck, turkey), sodium citrate 2.9%, fructose 2.4gm, penicillin, and streptomycin (100.000 IU and 100 mg, respectively) in 100 distal water. Sperms individual motility, live sperm percentage, sperms abnormalities checked at 0, 72, 144 hours of storage. Results of the present study revealed that quail egg yolk improved sperms, individual motility, live sperm percentage with longer life span and reduce sperms abnormalities, followed by Turkey, chicken and duck EYs respectively, Individual motility of the spermatozoa after 144 h of storage in quail EY extender were (36.00%± 1.20), which higher than turkey EY (32.30%± 1.30). However, these results higher and significantly (P˂ 0.05) when compare with chicken EY extender (24.60%± 2.30) and duck EY extender (19.00%± 1.50). Similar results of quail and turkey EYs were manifested in the percentage of live spermatozoa, which were (38.00%± 1.20), (33.30%± 1.30), (24.00%± 2.30), and (19.90%± 1.50), respectively. The duck EY was significantly lower (P˂ 0.05) when comparing between the four types of egg yolks after storage for 144 h. In conclusion: we advise potentially to use of a quail or turkey EYs extender for the chilled storage for ram epididymal sperms.

Morphology of the avian yolk sac.

The avian yolk sac is a multifunctional extraembryonic organ that serves not only as a site of nutrient (yolk) absorption, but also for early hemopoiesis, and formation of blood vessels. Although the yolk sac membrane being specialized to function as an extraembryonic absorptive organ, it is neither morphologically nor functionally part of the embryonic gut. Yolk absorption is by the phagocytic activity of the extraembryonic endoderm. I used cryohistology and resin embedding histology of complete developmental series of Japanese quail to document the development of the avian yolk sac and changes of the microscopic anatomy throughout development. This material is complemented by complete series of MRT-scans of live ostrich embryos from beginning of incubation through hatching. Considerable changes of size and shape of the yolk mass are documented and discussed as resulting from water flux from albumen to yolk associated with the biochemical activation of yolk sac proteins. During embryogenesis, the yolk sac endoderm forms villi that increase the absorptive surface and reach into the yolk ball. The histology of the absorptive epithelium is specialized for phagocytic absorption of yolk. During early developmental stages, the extraembryonic endoderm is single layered, but it eventually becomes several layers thick during later stages. The extraembryonic mesoderm forms an extensive layer of hematopoietic tissue; deep in this tissue lie the yolk sac vessels. During late stages of development, the erythropoietic tissue disappears, blood vessels are obliterated, and the yolk sac epithelium becomes apoptotic. Results are discussed in the light of the evolutionary history and phylogeny of the amniote egg.

Yolk immunoreactive corticosterone does not relate with maternal fecal glucocorticoids in a captive population of Greater Rheas (Rhea americana)

Maternal corticosterone in avian egg yolks may signal and prepare offspring for the prevailing conditions. However, this adjustment requires flexible mechanisms of regulation that lead to the absence of a correlation between hormone levels in the mother and the yolk. In this study, we examined whether yolk immunoreactive corticosterone and maternal glucocorticoid levels are related in the Greater Rhea (Rhea americana), a ratite species with a communal nesting system. During the intermediate laying period of the season, we carried out daily nest-observations to collect those eggs in which the laying female was identified. We also collected fresh fecal samples from the identified laying females to quantify their fecal glucocorticoid metabolite (FGM) levels during the yolk formation period (7 days before egg-laying). Yolk immunoreactive corticosterone and FGM levels were measured using a corticosterone125 radioimmunoassay kit, previously validated for the species. No significant relationships were found between female FGM and yolk immunoreactive corticosterone. Although futures studies are needed to elucidate the underlying mechanisms, our results suggest that Greater Rhea female may be able to control the distribution of corticosterone into their yolks, supporting the idea that this hormone may be mediating an adaptive maternal effect.

N-glycoproteomic analysis of duck egg yolk proteins: Implications for biofunctions and evolution

Egg yolk contains multifunctional glycoproteins, which modulate embryogenesis and indicate species-specific adaptation. Here, we conducted an N-glycoproteomic study of duck egg yolk (DEY) and identified 359 N-glycosites corresponding to 113 glycoproteins. The comparison of DEY N-glycoproteins with those of chicken egg yolk (CEY) revealed a higher N-glycosylation level in DEY proteins, suggesting a biological adaption to meet the requirements for embryo development by modulating protein structure and binding ability, including immune response and ligand transport. This variation may be correlated to the strong resistance to the influenza virus disease of duck. A large set of corresponding glycoproteins between DEY and CEY were detected with similar molecular functions, which suggested a relatively lower evolution speed of avian egg yolk proteins than that of egg white proteins.

Sterol-O acyltransferase 1 is inhibited by gga-miR-181a-5p and gga-miR-429-3p through the TGFβ pathway in endodermal epithelial cells of Japanese quail.

Nutrients are utilized and re-constructed by endodermal epithelial cells (EECs) of yolk sac membrane (YSM) in avian species during embryonic development. Sterol O-acyltransferase 1 (SOAT1) is the key enzyme to convert cholesterol to cholesteryl ester for delivery to growing embryos. During embryonic development, yolk absorption is concomitant with significant changes of SOAT1 mRNA concentration and enzyme activity in YSM. Presence of microRNAs (miRNAs) are observed in the embryonic liver and muscle during avian embryogenesis. However, the expression of miRNAs in YSM during embryogenesis and the involvement of miRNAs in lipid utilization are not known. Using a miRNA sequencing technique, we found several miRNA candidates and confirmed their expression patterns individually by real time PCR. MiRNA candidates were selected based on the expression pattern and their possible roles in inhibiting transforming growth factor beta receptor type 1 (TGFBR1) that would regulate the function of SOAT1. Similar to SOAT1 mRNA, the gga-miR-181a-5p expression was gradually elevated during embryonic development. However, the expression of gga-miR-429-3p in YSM was gradually decreased during embryonic development. The inhibitory effects of gga-miR-181a-5p or gga-miR-429-3p on the potential targets (SOAT1 and TGFBR1) were demonstrated by transient miRNA transfections in EECs. We also found that mutated TGFBR1 3'UTR prevented the direct pairings of gga-miR-181a-5p and gga-miR-429-3p. Treatment of TGFBR1 inhibitor, LY364947, further decreased SOAT1 transcription. Similar results were also observed by the miRNA transfection studies. The results showed the vital participations of gga-miR-181a-5p and gga-miR-429-3p in regulating TGFβ pathway, and affecting downstream SOAT1 expression and function in the YSM. This is indicative of possible regulation of avian yolk lipid utilization by changing YSM miRNA expressions.

3D Cultures of Salivary Gland Cells in Native or Gelled Egg Yolk Plasma, Combined with Egg White and 3D-Printing of Gelled Egg Yolk Plasma.

For salivary gland (SG) tissue engineering, we cultured acinar NS-SV-AC cell line or primary SG fibroblasts for 14 days in avian egg yolk plasma (EYP). Media or egg white (EW) supplemented the cultures as they grew in 3D-Cryo histology well inserts. In the second half of this manuscript, we measured EYP’s freeze-thaw gelation and freeze-thaw induced gelled EYP (GEYP), and designed and tested further GEYP tissue engineering applications. With a 3D-Cryo well insert, we tested GEYP as a structural support for 3D cell culture or as a bio-ink for 3D-Bioprinting fluorescent cells. In non-printed EYP + EW or GEYP + EW cultures, sagittal sections of the cultures showed cells remaining above the well’s base. Ki-67 expression was lacking for fibroblasts, contrasting NS-SV-AC’s constant expression. Rheological viscoelastic measurements of GEYP at 37 °C on seven different freezing periods showed constant increase from 0 in mean storage and loss moduli, to 320 Pa and 120 Pa, respectively, after 30 days. We successfully 3D-printed GEYP with controlled geometries. We manually extruded GEYP bio-ink with fluorescence cells into a 3D-Cryo well insert and showed cell positioning. The 3D-Cryo well inserts reveal information on cells in EYP and we demonstrated GEYP cell culture and 3D-printing applications.

Comparative proteomic analysis of hen egg yolk plasma proteins during embryonic development.

Avian egg yolk provides essential nutrients and physiological support for the developing embryo. To reveal the dynamics of yolk proteins during the entire period of incubation, we analyzed the alterations of egg yolk plasma proteins at different times during incubation (day 0, 7, 14, and 18). Day14 (D14) of incubation was considered as the key point on the alteration of egg yolk proteins according to the SDS-PAGE analysis. The two-dimensional electrophoresis-based comparative proteomic analysis was conducted, and 26 spots representing 13 proteins were detected with significant changes in abundance. An accelerating transfer of ovalbumin from egg white into egg yolk was observed at D14 in fertilized eggs but not detected in unfertilized eggs, indicating an unrevealed absorbing pathway for the egg proteins/peptides particularly in fertilized eggs. Meanwhile, the abundance of yolk riboflavin-binding protein constantly decreased after D14, which might meet the need for essential riboflavin during embryo development. PRACTICAL APPLICATIONS: These findings provide fundamental insight into the effects of incubation on egg yolk plasma protein alterations during the entire embryonic development for a better understanding of plasma protein biological functions, especially in nutrient transportations and the formation of embryonic organs.

MiRNAs regulate the expression of sterol‐O acyltransferase 1 through inhibiting the 3′UTR of TGFβ receptor type 1 during embryonic development

Nutrients are utilized and re‐constructed by endodermal epithelial cells (EECs) of yolk sac membrane (YSM) in avian species during embryonic development. Sterol‐O acyltransferase 1 (SOAT1) is the key enzyme to convert cholesterol to cholesteryl ester, and for packaging into very‐low‐density lipoproteins for further delivering to growing embryos. During embryonic development, the quick absorption of yolk is matched with the significant changes of SOAT1 mRNA and enzymatic activity. MicroRNAs (miRNAs), groups of highly conserved small non‐coding RNA molecules, are usually ~23 nucleotides across species, serving classical biofunctions as mRNA‐targeting cleavage, translation repression and mRNA deadenylation. miRNAs have been identified to regulate angiogenesis, invasion and metabolism during mammalian development. However, the involvement and importance of miRNAs in lipid utilization during avian embryogenesis remains unclear.Using a RNA sequencing technique, we found many miRNAs expressed during quail embryonic development. We confirmed the expression pattern with real time PCR and several miRNAs (gga‐miR‐181a‐5p, gga‐miR‐133a‐5p, and gga‐miR‐429‐3p) were selected because they are candidates targeting to the receptor (TGFβ receptor type 1, TGFBR1) that regulates the expression of SOAT1. Similar to SOAT1 mRNA concentration, the gga‐miR‐181a‐5p expressions were gradually elevated during development, but gga‐miR‐429‐3p were presented in the opposite direction. Moreover, transfection with gga‐miR‐181a‐5p, gga‐133a‐5p, or gga‐429‐3p inhibited TGFBR1 and SOAT1 mRNA expressions in EECs. The 3′ untranslated region (3′UTR) of TGFBR1 is speculated to be one of the targets of miRNAs (gga‐miR‐181a‐5p, gga‐miR‐133a‐5p, and gga‐miR‐429‐3p).Taken together, miRNAs expression during embryonic development can regulate SOAT1 expression through inhibiting the 3′UTR of TGFBR1. This is indicative of possible regulation of avian yolk lipid utilization and modification of hatchability by modifying miRNA expression.Support or Funding InformationMinistry of Science and Technology, Taiwan (ROC)This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Avian yolk androgens are metabolized rather than taken up by the embryo during the first days of incubation.

Several studies show effects of yolk androgens in avian eggs on the phenotype of the offspring. Yolk hormone concentrations decline strongly within the first few days of incubation. Although early embryonic uptake of yolk androgens is suggested by the presence of radioactivity in the embryo when eggs are injected with radiolabelled androgens, these studies do not verify the chemical identity of radioactive compound(s), although it is known that these androgens can be metabolized substantially. By using stable isotope-labelled testosterone and androstenedione in combination with mass spectrometry, enabling verification of the exact molecular identity of labelled compounds in the embryo, we found that after 5 days of incubation the androgens were not taken up by the embryo. However, their concentrations in the entire yolk albumen homogenates declined strongly, even when corrected for dilution by albumen and water. Our results indicate metabolism of maternal androgens, very likely to 5β-androstane-3α,17β-diol, etiocholanolone and their conjugated forms. The results imply that the effects of increased exposure of the embryo to maternal androgens take place either before this early conversion or are mediated by these metabolites with an as yet unknown function, opening new avenues for understanding hormone-mediated maternal effects in vertebrates.

Egg Yolk as Means for Providing Essential and Beneficial Fatty Acids

AbstractThe new American Dietary Guidelines now recommend optimizing the types of fat consumed instead of reducing or eliminating fat from the diet. Chicken eggs are a means to deliver essential and beneficial human dietary fatty acids (FA), and can be staple component of healthy eating behavior. Additionally, polyunsaturated fatty acids can be increased in the avian egg yolk by simply incorporating selected lipid sources into the avian diet. Poultry feed rich in omega‐3 FA (omega‐3) has allowed commercialization of enriched eggs containing up to 600 mg of omega‐3. Conjugated linoleic acid (CLA) has also been used in the research setting to enrich eggs to provide a portion of the 3–4 g CLA day−1 needed to promote weight loss to combat obesity. However, Americans consume only 50% of the omega‐3 recommended adequate intake, and average CLA consumption is under 600 mg day−1. While a variety of foods are naturally rich in omega‐3, conventional sources of CLA are limited to bovine milk and meat, which do not provide enough CLA to produce clinical effects in a balanced diet. Since eggs and egg‐based products are common in the Western diet, eggs enriched with both omega‐3 and CLA using dietary additions to poultry feed may promote consumption of the recommended levels of these FA. This article reviews the design of poultry eggs with enhanced lipid profiles through dietary intervention, and discusses the future direction of enriched egg research.

Avian Egg Yolk Antibodies (IgY) and their Potential Therapeutic Applications for Countering Infectious Diseases of Fish and Aquatic Animals

Avian Egg Yolk Antibodies (IgY) and their Potential Therapeutic Applications for Countering Infectious Diseases of Fish and Aquatic Animals