The synthesis and secretion of vitellogenin by the ovary of Rhodnius prolixus was investigated. Using whole ovary or epithelial cells isolated from follicles of different sizes, it is shown that the follicle cells are a site of synthesis for this protein in the ovary. The ovaries or follicle cells were incubated in vitro with [(35)S]-methionine or (32)Pi and the secretion of newly synthesized o...

Phenolic compounds are widely distributed in the natural environment, typically existing as a mixture at the nanogram or microgram per liter level. Among the phenolic compounds, 4-nonylphenol, 4-t-octylphenol, bisphenol A and 2,4-dichlorophenol attract the most concern due to their abundance and risks within the natural environment. The former three chemicals are known as endocrine disruptors c...

We have developed a system for the in vitro transcription of specific genes in rooster liver chromatin by endogenous RNA polymerase II that maintains the specificity of transcription in vivo. Radioactive transcripts synthesized in vitro were identified and quantitated by hybridization to a vast excess of cloned cDNA. The cDNA preparations employed corresponded to vitellogenin mRNA, the synthesi...

In vitro transcription competition with oligonucleotides has shown that a down regulating factor can be displaced by a methylated oligonucleotide covering a specific region of the avian vitellogenin II gene promoter (Proc. Natl. Acad. Sci USA, (1990) 87, 3047-3051). Gel mobility shift and competition assays show that a protein binding preferentially to methylated DNA (MDBP-2) is present in frac...

The oocyte is the starting point for a new generation. Most of the machinery for DNA and protein synthesis needed for the developing embryo is made autonomously by the fertilized oocyte. However, in fish and in many other oviparous vertebrates, the major constituents of the egg, i.e. yolk and eggshell proteins, are synthesized in the liver and transported to the oocyte for uptake. Vitellogenesi...

We have developed a system for the in vitro transcription of specific genes in rooster liver chromatin by endogenous RNA polymerase II that maintains the specificity of transcription in uiuo. Radioactive transcripts synthesized in vitro were identified and quantitated by hybridization to a vast excess of cloned cDNA. The cDNA preparations employed corresponded to vitellogenin mRNA, the synthesi...

In oviparous vertebrates, vitellogenin (VTG) is the major yolk precursor synthesized in the liver of sexually mature females during the reproductive period. In males, the VTG gene is silent, but it may be activated by estradiol-17β (E2) or estrogen-like substances. Until now, extra-hepatic expression and synthesis of VTG after estrogen exposure has been reported only for aquatic vertebrates. Th...