Vitellogenesis or maternal yolk formation is considered critical to the reproduction of egg-laying animals. In invertebrates, however, most of its regulatory genes are still unknown. Via a combined mapping and whole-genome sequencing strategy, we performed a forward genetic screen to isolate novel regulators of yolk production in the nematode model system Caenorhabditis elegans. In addition to ...

A partial cDNA clone for the 48,000 dalton yolk polypeptide gene from Anastrepha suspensa was isolated from a cDNA expression library using a yolk polypeptide antibody probe and hybridization to the Drosophila melanogaster yolk protein 1 gene. The sequenced DNA has greatest homology to the yolk protein genes from Ceratitis capitata, D. melanogaster, and Calliphora erythrocephala and, similar to...

The heat resistance and growth possibilities of various members of the Micrococcaceae in egg yolk and egg yolk with added salt were determined. Egg yolk alone protected members of the Micrococcaceae considerably against heat. Whereas in water Staphylococcus aureus S6 had a decimal reduction time (D) value of 66 s at 55 degrees C, its D value in egg yolk at the same temperature was 246 s. In sal...

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Egg yolk is the most commonly used cryoprotective agent for sperm cryopreservation of several species.The objective of this experiment was to compare the effectiveness of egg yolk from four avian species(domestic chicken, duck, turkey and pigeon) on sperm quality following cryopreservation of the ram semen.Ejaculates were collected, using an electroejaculator, from six fertile rams. Samples wer...

The objective of this study was to develop a statistical model for predicting egg yolk contamination level in egg white using a spectroscopic method. Eggs that were stored for 0, 0.5, 1.0, 1.5, 2.5, and 6.5 wk at 4 C were manually processed to cleanly separate the yolk from the white. Egg white samples containing 0e0.5% (w/w) of yolk were prepared by adding yolk to the white and further dilutin...

Mutant mice deficient in glucose-6-phosphate dehydrogenase were used to induce teratomas. This enzyme is linked to the X chromosome, which can be inactivated in female embryo. The differences in the enzyme activity between yolk sac mesoderm and embryo versus yolk sac endoderm can be detected in female concepti by using appropriate crosses of wild-type and G6PD-deficient mice. Histochemical stud...

Hormonally mediated maternal effects link maternal phenotype and environmental conditions to offspring phenotype. The production of lipid-rich maternal yolk precursors may provide a mechanism by which lipophilic steroid hormones can be transported to developing yolks, thus predicting a positive correlation between yolk precursors in mothers and androgen levels in eggs. Using rockhopper penguins...