Previous experiments have proved that thermodynamically unstable calcium carbonate vaterite can exist for long periods in the yolk sac of a pigeon embryo. The aim of this article was to demonstrate the effect of in vitro mineralization of yolk sac fluid on calcium carbonate by direct precipitation. Experiments were conducted using pigeon yolk sac fluid and using lecithin extracted from pigeon y...

During embryogenesis, organisms with lecithotrophic indirect development usually accumulate large quantities of energetic reserves in the form of yolk that are necessary for larval survival. Since all sponges have lecithotrophic development, yolk formation is an ineludible step of their embryogenesis. Sponge yolk platelets have a wide range of morphological forms, from entirely lipid or protein...

Maternal lipoproteins provide nutrients to the fetus via the placenta, yolk sac, and uterine membrane plus decidua. To determine the transport processes that are responsible for the removal of lipoproteins from the maternal circulation, we measured the clearance rates of maternal LDL and HDL in vivo, as well as the tissue distribution of expression of the LDL receptor, glycoprotein 330 (gp330) ...

A method is described for the chromatographic separation of mixtures of egg-yolk proteins of low solubility, by using a hydrophobic column (phenyl-Sepharose) and eluting with increasing concentrations of aqueous urea at low pH. The resolving power of the method was established by tests on proteins and protein fragments of known sequence. The theoretical basis for the method remains, however, un...

Current commercial broiler products are derived from the crosses of various strains at the primary breeder level. This study investigated chick development, yolk utilization, and early growth rate of males from 8 broiler breeder strains. These strains were a combination of both specialized and commercial-line products. At hatch, 110 male chicks per strain were weighed and wing-banded, and chick...

Egg yolk undergoes an irreversible gelation process at temperatures below −6 °C, which greatly impairs its application and increases apparent viscosity. This work was aimed to investigate the effect of salt pH in preventing frozen-thawed egg yolk. Before freezing, 5% added into pasteurized liquid yolk, then adjusted different levels (5.7, 6.0 6.3) with citric acid. After that, stored −18 °C for...

Progenitor cells capable of giving rise to functional macrophages in in vitro culture were first detectable in the fetal yolk sac of the mouse between day 7 and 8 of gestation. Macrophage progenitors were not detectable outside the yolk sac until day 11. Although the early yolk sac contained macrophage precursors, no cells with the morphologic or functional characteristics of mouse promonocytes...

Transcription of the three yolk protein genes of Drosophila melanogaster is under strict developmental regulation. Understanding the mechanism of this regulation requires examination of the DNA sequences and protein factors necessary for normal transcriptional control. We have identified a sequence-specific DNA-binding protein, yolk protein factor 1 (YPF1), that has high affinity for a 31-bp se...

The capacity of cecropia vitellogenic follicles to form yolk during short-term in vitro incubation in female blood was analyzed by labeling with fluorescein-conjugated serum globulin, tritiated cecropia blood proteins, or tritiated amino acid. As judged by fluorescence microscopy or autoradiography, yolk formation during 3-8 hr in vitro was similar in rate and in protein uptake specificity to t...

The objective of this study was to investigate the deposition rule of yolk cholesterol in Lushi Green-shelled and Silky Fowl layers. A total of 90 layers of each breed were selected at an age of 15 to 51 weeks. Productive performance was recorded on a weekly basis, whereas yolk cholesterol was determined at 4-week intervals from 21 to 51 weeks of age. The average yolk cholesterol content of Sil...