• Journal of Life Science
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• v.10 no.5
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• pp.475-483
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• 2000

Normally, aerobic cells are protected from the damage of free radicals by antioxidative enzymes such as catalase, superoxide dismutase (SOD), glutathione (GSH) peroxidase and GSH-S-transferase. In this study, we have investigate the effect of egg yolk protein hydrolysates on antioxidative activity and the activity of antioxidative enzyme in cultured hepatocytes (Chang). Without the pretreatment with hydrolysate, about 50% of the hepatocytes were killed within 2h by 225$\mu$M tert-butyl hydroperoxide (t-BHP). By contrast, fewer than 20% of the 5 K hydrolysate (permeate from 5 kDa membrane and not passed through 1 kDa membrane)-pretreated hepatocytes were killed by the same concentrations of t-BHP. In addition, the activities of catalase, GSH peroxidase and GSH-transferase were significantly increasing with the treatment of 5 K hydrolysate. These results suggest that 5 K hydrolysate exerts antioxidative effect by increasing activity of antioxidative enzymes.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.3
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• pp.448-458
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• 2009

It has been well documented from animal and human studies that conjugated linoleic acid (CLA) has numerous beneficial effects on health. In chickens, CLA exerts many effects on performance ranging from egg quality and yolk lipids to meat quality. Although there are several CLA isomers available, not all CLA isomers have the same incorporation rates into egg yolk: cis-9,trans-11 and trans-10,cis-12 CLA isomers are more favorably deposited into egg yolk than other isomers investigated, but of the two isomers, the former has a higher incorporation rate than the latter. CLA alters the amounts and profiles of lipids in plasma, muscles and liver. Furthermore, increased liver weight was reported in chickens fed dietary CLA. As observed in egg yolk, marked reduction in intramuscular lipids as well as increased protein content was observed in different studies, leading to elevation in protein-to-fat ratio. Inconsistency exists for parameters such as body weight gain, feed intake, feed conversion ratio, egg production rate and mortality, depending upon experimental conditions. One setback is that hard-cooked yolks from CLA-consuming hens have higher firmness as refrigeration time and CLA are increased, perhaps owing to alterations in physico-chemistry of yolk. Another is that CLA can be detrimental to hatchability when provided to breeders: eggs from these breeders have impaired development in embryonic and neonatal stages, and have increased and decreased amounts of saturated fatty acids and monounsaturated fatty acids (MUFAs), respectively. Thus, both problems can be fully resolved if dietary sources rich in MUFAs are provided together with CLA. Emerging evidence suggests that CLA exerts a critical impact on stress and immune functions as it can completely nullify some of the adverse effects produced by immune challenges and reduce mortality in a dose-dependent manner. Finally, CLA is a key regulator of genes that may be responsible for lipid metabolism in chickens. CLA down-regulates both expression of the gene encoding stearoyl-CoA desaturase-1 and its protein activity in the chicken liver while up-regulating mRNA of sterol regulatory element-binding protein-l.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.8
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• pp.1174-1179
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• 2009

An experiment was conducted to study the effect of post-hatch feed deprivation on yolk sac utilization andsubsequent performance of young broiler chickens (280) up to 35 days of age. The experimental treatments included access to feed at 8 h intervals after hatch, up to 48 h (0, 8, 16, 24, 32, 40 or 48 h). Water was offered ad libitum to all the groups immediately after placement. Results indicated that chicks with access to feed immediately after hatch used up the residual yolk more quickly. Access to feed between 8-24 h post-hatch, supported faster utilization of residual yolk compared to those chicks that remained unfed for 40-48 h (p<0.05). Further, deprivation of feed up to 24 h did not alter the lipid and protein contents in residual yolk, but fasting of chicks beyond 24 h (32, 40 and 48 h) led to retention of higher lipid and lower protein content in the yolk sac (p<0.05). At 7 days of age, the weights of proventiculus and gizzard were not affected by feed deprivation up to 48 h. However, the liver, pancreas and jejunum recorded significantly (p<0.05) heavier weights in chicks that were fed during the initial 24 h period compared to delayed feeding (32-48 h). Chicks fed within 24 h after hatch gained significantly (p<0.05) higher weight at 5 weeks of age than those that received feed between 32 and 48 h. Feed deprivation for 48 h was more detrimental to growth than 24-40 h. This study revealed the significance of early posthatch feeding (<24 h) on faster utilization of yolk sac nutrients and optimum development of intestines and organs, culminating in improved weight gain (>10.5%) of broilers at 5 weeks of age.

• Journal of the East Asian Society of Dietary Life
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• v.20 no.1
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• pp.77-83
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• 2010

The study was conducted to investigate the effect of particle size on the physicochemical properties of egg yolk-rice porridge. The pH of egg yolk-rice porridge was decreased when compared to that of the control, while the lightness and yellowness was increased as the rice particle size increased. The viscosity of whole particle egg yolk porridge was highest among the three porridges at $40^{\circ}C$. The protein content of the egg yolk-rice porridge was increased three-fold, when compared to that of the rice porridges. The total amino acid content of egg yolk-rice porridge was 1,500.6 mg/100 g, while that of rice was 1,147.5 mg/100 g. The Lys and Thr content of the amino acid content of egg yolk-rice porridge were also increased. Sensory evaluation results revealed that the half particle size rice egg yolk-rice porridge had the highest scores in color, taste and over-all preference. Based on these results, the half particle size egg yolk-porridge had good quality with respect to both the physicochemical and nutritional properties.

• Journal of Life Science
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• v.10 no.1
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• pp.45-51
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• 2000

Ovarian development and yolk protein (YP) of mushroom fly, Coboldia fuscipes, were characterized. C. fuscipes has a pair of ovaries, composed of 130∼140 ovarioles, respectively. Ovarian development begins at 1 day of pupa, and growth of the ovaries continued to become a matured shape at 1 day after emergence. The YP of C. fuscipes identified by SDS-PAGE analysis revealed that the protein is composed of three subunits, designated YP1 (61 kDa), YPS(50 kDa), and YP3 (47 kDa). These three subunits of YP gradually decreased during embryogenesis. The YP was first detected in the 3 day-old pupal ovary and was continually detected up to 2 day-old adult, but not in the hemolymph. Furthermore, Western blot analysis of male and female adult hemolymph and ovary revealed that the antibodies against YP1, YP2, and YP3 reacted with three YP bands in ovary and egg extract, respectively. However, this reactivity was not observed in the male and female hemolymps. Therefore, it is assumed that the UP of C. fuscipes is synthesized in the ovary at 3 days after pupation.

• The Korean Journal of Zoology
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• v.35 no.3
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• pp.271-276
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• 1992

20-hydroxvecdysone (20-HE) seems to be related in the regulation of vitellogenesis in Drosophifa sp. (robwta species sroup). Although yolk proteins (YPs) synthesis does not occur at a high rate in fat body cells of one daw-old female after eclosion, application of 20-HE to isolated abdomens deprived of anterior endocrine glands stimulated the synthesis and secretion of YPs into the hemolvmph. An injection of 0.3 $\mul$ of a 10-s M 20-HE was sufficient topromote synthesis and secretion of YPs in isolated abdomens. The response of isolated automens to hormones was first detected between 2 hr and 3 hr after treaDent of 10-s M 20-HE. Transcript analysis showed that the effect of 20-HE on yolk protein synthesis was mediated at the level of transcription.

• Food Science and Biotechnology
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• v.17 no.6
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• pp.1289-1293
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• 2008

Fresh egg yolk (EY) was enzymatically modified using phospholipase $A_2$ ($PLA_2$) to produce an enzymatically modified-egg yolk powder (EM-EYP). The EM-EYP offered significantly higher emulsifying activity, emulsion stability, protein solubility, and mayonnaise stability than the control EYP. By employing $PLA_2$ in the enzymatic modification process, structural changes occurred in the phospholipids and lipoproteins of the yolk, and cleavage of apo-high density lipoprotein (HDL) components (Mw 105 kDa) was detected by sodium dodecyl sulfate-polyaerylamide gel electrophoresis (SDS-PAGE). Based on its functional properties, EM-EYP has great potential as a replacement for fresh EY in the production of processed food products such as mayonnaise.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.11
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• pp.1665-1670
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• 2006

The objective of this research was to provide the characterization and method for producing anti-E. coli O157:H7 antibodies in egg-laying hens and to determine if the antibody can restrain the proliferation of E. coli O157:H7 in-vitro. Selected antigenic fractions (whole cell, outer membrane protein and lipopolysaccharide (LPS)) from E. coli O157:H7 were injected to hens in order to produce anti-E. coli O157:H7 antibodies. The immune response and the egg yolk antibodies of laying hens against the whole cell, outer membrane protein and LPS antigens were monitored by ELISA. The level of antibodies against whole cell antigen monitored through ELISA sharply increased after the initial immunization, and it was found to be maximum on day 49 however, the level was maintained up to day 70. Antibodies (5 mg/ml) directed against the whole cell inhibited E. coli proliferation 10-13 times more than outer membrane protein or LPS. The antibody response against the whole cell antigens appeared to have higher activity in restraining the proliferation of E. coli O157:H7 than antibody against outer membrane protein or LPS. Results reflected that increasing the IgY's in the egg yolk could prevent greater economic losses due to human and animal health from pathogenic bacteria i.e. E. coli O157:H7.

• Journal of Sericultural and Entomological Science
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• v.30 no.2
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• pp.96-104
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• 1988

Vitellin, the major yolk protein of the silkworm, Bombyx mori was pruified, and its immunological properties and the quantitative changes during embryogenesis were studied. The ovary transplantation into male hosts was also carried out to find its effect on the yolk protein synthesis. The pupal vitellogenin and the egg vitellin of Bombyx mori were purified by DEAE-cellulose column chromatography. These two female specific proteins showed the same mobility in the polyacrylamide gel electrophoresis and the same reaction in the double immunodiffusion test. The immunological identity was also observed between the vitellins of Bombyx mori and Bombyx mandarina. The rudimentary ovaries transplanted into the male hosts of silkworms produced eggs without vitellin, indicating that the yolk precursors synthesized in other female organ beyond the ovary were necessary to produce vitellins. The major yolk protein, vitellin was disintegrated and utilized mostly during late stage of embryogenesis. It was different characteristics from the egg specific protein, which was utilized continuously from the early embryonic stage.

• Korean Chemical Engineering Research
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• v.50 no.4
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• pp.659-665
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• 2012

IgY (Immunoglobulin Yolk) in egg yolk corresponds to IgG (Immunoglobulin G) in animal serum and plays an important role as immunological proteins in intestines. Carrageenan and Arabic gum were used as pretreatment agents to purify IgY from fresh egg yolk. DEAE (Diethylaminoethyl) Sepharose column in FPLC (Fast Protein Liquid chromatography) was an ion exchange tool to remove contaminants as well as to elute IgY from the column. GF HPLC (Gel Filtration High Performance Liquid Chromatography) enables to measure the molecular weights of IgY and to identify the purified IgY by comparing the molecular weight of standard IgY with the purified one. IgY is a heterogeneous group of different molecular weight and ionic properties, which was investigated with various IE HPLC (Ion Exchange High Performance Liquid Chromatography) columns such as AX, CX and SCX. Three peaks of IgY were separated in the AX column under the conditions of 0.5 M NaCl and pH=8. The SCX column also gave the three peaks of IgY at 0.5 M NaCl and pH=5.