9. The effect of antiestrogens on chromatin associated estrogen receptors and egg yolk protein synthesis in the rooster liver

1975 ◽  
Vol 6 (11-12) ◽  
pp. vii
Author(s):  
Michael Gschwendt
Keyword(s):  
Protein Synthesis ◽  
Estrogen Receptors ◽  
Egg Yolk ◽  
Yolk Protein

scholarly journals Differential subnuclear distribution of polyadenylate-rich ribonuclei acid during induction of egg-yolk protein synthesis in male Xenopus liver by oestradiol-17β

1975 ◽  
Vol 150 (3) ◽  
pp. 345-355 ◽  
Author(s):  
J R Tata ◽  
B Baker
Keyword(s):  
Molecular Weight ◽  
Protein Synthesis ◽  
High Molecular Weight ◽  
Sodium Dodecyl ◽  
Fold Increase ◽  
Egg Yolk ◽  
Yolk Protein ◽  
Stable Form ◽  
Nuclear Rna ◽  
Vitellogenin Mrna

A 4-8-fold increase in the rate of hepatic nuclear RNA synthesis occurred within 11 h after a single injection of oestradiol-17 β to male Xenopus to induce egg-yolk protein synthesis. 2. By using a gentle procedure for fractionating nuclei into their major structurally different components [J. R. Tata& B. Baker (1974) Exp. Cell Res. 83. 111-124], it was found that the hormone-induced increase in the total amount of newly made RNA was associated with a 2-10-fold increase in the poly(A) content of nuclear RNA. 3. When the poly (A) content of nuclear RNA was determined by hybridization to poly[3H](U) or specific binding to oligo(dT)-cellulose, most of the increase (10-fold) in poly (A) content of newly synthesized RNA was associated with the euchromatin fractions, whereas the increase was less marked in the other subnuclear fractions. 4. Resolution of nuclear RNA into poly (A)-poor and poly(A)-rich RNA species by chromatography on oligo(dT)-cellulose, followed by polyacrylamide-gel electrophoresis with sodium dodecyl sulphate or in the pressence of 99% formamide, revealed that the hormone caused a preferential enhancement of high-molecular-weight (25S-60S) poly (A)-rich HnRNA (heterogeneous nuclear RNA,) much of which was associated with euchromatin and not with the nuclear sap. 5. Induction of vitellogenin in male frogs was in particular characterized by the appearance of a high-molecular-weight polyadenylated component exhibiting a peak at 35-36S, i.e. a molecular weight of approx. 2.05×10(6)+∕-0.15×10(6). Although there is no evidence as yet that such a polyadenylated high-molecular-weight nuclear RNA species contains sequences corresponding to vitellogenin mRNA, it is possible that a high proportion of the most stable form of the putative nuclear precursor to vitellogenin mRNA induced by oestrogen in male Xenopus liver may be only marginally bigger than the cytoplasmic mRNA, and may at any one time be predominantly associated with the euchromatin fraction.

VIEWPOINT. An hypothesis to explain the linkage between kakapo (Strigops habroptilus) breeding and the mast fruiting of their food trees

2008 ◽  
Vol 35 (1) ◽  
pp. 1 ◽  
Author(s):  
Andrew E. Fidler ◽  
Stephen B. Lawrence ◽  
Kenneth P. McNatty
Keyword(s):  
Egg Yolk ◽  
Ovarian Follicles ◽  
Yolk Protein ◽  
Egg Laying ◽  
Food Plants ◽  
Mast Seeding ◽  
Future Research ◽  
Yolk Protein Genes ◽  
Hypothetical Mechanism ◽  
Future Research Directions

An important goal in the intensive conservation management of New Zealand’s critically endangered nocturnal parrot, kakapo (Strigops habroptilus), is to increase the frequency of breeding attempts. Kakapo breeding does not occur annually but rather correlates with 3–5-year cycles in ‘mast’ seeding/fruiting of kakapo food plants, most notably podocarps such as rimu (Dacrydium cupressinum). Here we advance a hypothetical mechanism for the linking of kakapo breeding with such ‘mast’ seeding/fruiting. The essence of the hypothesis is that exposure to low levels of dietary phytochemicals may, in combination with hepatic gene ‘memory’, sensitise egg yolk protein genes, expressed in female kakapo livers, to oestrogens derived from developing ovarian follicles. Only in those years when the egg yolk protein genes have been sufficiently ‘pre-sensitised’ by dietary chemicals do kakapo ovarian follicles develop to ovulation and egg-laying occurs. While speculative, this hypothesis is both physiologically and evolutionarily plausible and suggests both future research directions and relatively simple interventions that may afford conservation workers some influence over kakapo breeding frequency.

Dietary components modulate yolk protein gene transcription in Drosophila melanogaster

Development ◽  
1988 ◽  
Vol 103 (1) ◽  
pp. 119-128 ◽  
Author(s):  
M. Bownes ◽  
A. Scott ◽  
A. Shirras
Keyword(s):  
Protein Synthesis ◽  
Drosophila Melanogaster ◽  
Juvenile Hormone ◽  
Gene Transcription ◽  
Protein Gene ◽  
Yolk Protein ◽  
Complete Medium ◽  
General Effect ◽  
Total Recovery ◽  
Insect Hormones

The three yolk proteins of Drosophila melanogaster begin to be synthesized at eclosion. Transcription of the genes is regulated by the genes tra, tra-2 and dsx and also by the insect hormones, juvenile hormone and 20-hydroxyecdysone. We show that there is yet another level of control which is dependent upon feeding. Females that are starved from eclosion show a basal level of yolk protein gene transcription, which is rapidly increased when a complete diet is supplied. We show that the effect is not due to incorrect development of the fat body and is unlikely to be solely due to a general effect on protein synthesis. Later in development, cessation of feeding leads to selective inhibition of yolk protein synthesis and hence egg production. The effects of starvation can be partially overcome by 20-hydroxyecdysone, juvenile hormone, casein, amino acid mix or sucrose, but only a complete medium or live yeast brings about total recovery. Using yp1-Adh fusions (fusions of the promoter region of yp1 to the structural gene for Adh), the DNA sequence required for this diet-enhanced transcription has been located within an 890 bp fragment upstream of the yp1 gene. The insect hormones do not operate on this same DNA fragment.

Extraction of Lipid-Protein Complexes from Egg Yolk

1972 ◽  
Vol 55 (5) ◽  
pp. 975-978
Author(s):  
J G Navarro ◽  
F Borie ◽  
J Saavedra
Keyword(s):  
Fatty Acids ◽  
Solvent Extraction ◽  
Enzymatic Hydrolysis ◽  
Free Fatty Acids ◽  
Protein Complexes ◽  
Egg Yolk ◽  
Yolk Protein ◽  
Residual Lipid ◽  
Mode Of Attachment ◽  
Hydrolysis Of

Abstract A residual lipid which is not removed by solvent extraction was detected and determined after enzymatic hydrolysis of defatted egg yolk protein. Free fatty acids were found to be the type of lipid bonded to the egg yolk protein. The mode of attachment of these fatty acids to the egg yolk protein is suggested and the composition of the fatty acids is reported.

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