The biosynthesis of spermidine as a key regulatory step in the hormonal induction of milk-protein synthesis in the organ culture of the mouse mammary gland

1982 ◽  
pp. 577-580
Author(s):  
Takami Oka ◽  
Nobuyuki Terada ◽  
John W Perry
Keyword(s):  
Protein Synthesis ◽  
Mammary Gland ◽  
Organ Culture ◽  
Milk Protein ◽  
Mouse Mammary Gland ◽  
Hormonal Induction

A STUDY ON THE EFFECT OF INSULIN ON DNA, RNA AND PROTEIN SYNTHESIS IN MOUSE MAMMARY GLAND TISSUE IN ORGAN CULTURE

1971 ◽  
Vol 50 (2) ◽  
pp. 241-249 ◽  
Author(s):  
D. Y. WANG ◽  
VICKY AMOR
Keyword(s):  
Protein Synthesis ◽  
Mammary Gland ◽  
Organ Culture ◽  
Mouse Mammary Gland ◽  
Metabolic Inhibitors ◽  
Synthetic Activity ◽  
Insulin Stimulation ◽  
Mammary Gland Tissue ◽  
Gland Tissue ◽  
Rna And Protein Synthesis

SUMMARY The rates of synthesis of DNA, RNA and protein of mouse mammary gland explants in organ culture have been determined. Stimulation with insulin resulted in maximal rates of synthesis of these components, all occurring between 18 and 22 h of culture. The use of metabolic inhibitors of DNA, RNA or protein synthesis showed that after insulin stimulation, inhibition of any one of these processes was associated with a reduction in the synthesis of the other two components. Also the maximal rate of protein synthesis is governed by the net amount of RNA formed throughout the period of culture. Evidence is presented that the stimulation of DNA, RNA or protein synthesis by insulin is not due to increased transport of amino acids and that insulin appears to act rapidly on processes which subsequently lead to enhanced synthetic activity.

Utilization of dipeptides by the caprine mammary gland for milk protein synthesis

1994 ◽  
Vol 267 (1) ◽  
pp. R1-R6 ◽  
Author(s):  
F. R. Backwell ◽  
B. J. Bequette ◽  
D. Wilson ◽  
A. G. Calder ◽  
J. A. Metcalf ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Mammary Gland ◽  
Blood Cell ◽  
Red Blood Cell ◽  
Milk Protein ◽  
Common Mechanism ◽  
Dairy Goats ◽  
Peptide Hydrolysis ◽  
Lactating Mammary Gland

Specific use by the mammary gland in vivo of amino acids (AA) of peptide origin has been demonstrated in lactating dairy goats using a dual-labeled tracer technique involving close-arterial (external pudic artery, EPA) infusion of 13C-labeled dipeptides. The extent of utilization does not appear to differ for glycyl-L-[1-13C]phenylalanine and glycyl-L-[1-13C]leucine, perhaps indicative of a common mechanism by which AA are incorporated from peptide into milk protein. [1-13C]phenyl-alanine of peptide origin appears to be concentrated within the red blood cell, suggesting a role for the erythrocyte in peptide metabolism in vivo. In conclusion, it appears that the lactating mammary gland of goats has the ability to utilize AA of peptide origin for milk protein synthesis, and while the mechanism by which [1-13C]AA are incorporated into milk protein is not clear, it may involve peptide hydrolysis by either mammary cell surface or red blood cell hydrolases followed by uptake of liberated AA by the mammary gland.

Milk Protein Precursors in the Goat During Late Lactation

1993 ◽  
Vol 1993 ◽  
pp. 1-1
Author(s):  
B.J. Bequette ◽  
F.R.C. Backwell ◽  
A.G. Calder ◽  
J.A. Metcalf ◽  
D. Wray-Cahen ◽  
...  
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Mammary Gland ◽  
Milk Protein ◽  
Protein S ◽  
Dairy Goats ◽  
Protein Precursor ◽  
Previous Hypothesis ◽  
Casein Protein ◽  
Isotope Kinetics

Previously, we have reported on work in dairy goats using stable isotope kinetics to examine the precursors for milk protein synthesis (1). Contrary to a previous hypothesis (2), these results suggested that blood free amino acids (AA) are not simply transported into the mammary gland and incorporated directly into milk protein. Although the latter may still occur, a substantial amount of the AA for milk protein synthesis appears to be channelled through constitutive mammary gland protein(s) first. Moreover, the data indicated that a proportion (12-20%) of the casein protein precursor may be derived from extra-mammary sources other than blood free AA, e.g. peptides and/or proteins. It may be possible therefore to alter milk protein synthesis by the provision of different forms of precursor amino acids. Since the previous study was in goats during early lactation (day 61 ± 11), the present study reports on the precursors for milk protein synthesis in goats during late lactation, and allows a comparison between stages of lactation.

Eukaryotic elongation factor-2 (eEF-2) activity in bovine mammary tissue in relation to milk protein synthesis

2002 ◽  
Vol 69 (2) ◽  
pp. 205-212 ◽  
Author(s):  
CLAUS T. CHRISTOPHERSEN ◽  
JAKOB KARLSEN ◽  
METTE O. NIELSEN ◽  
BENT RIIS
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Mammary Gland ◽  
Diphtheria Toxin ◽  
Milk Protein ◽  
Elongation Factor ◽  
Mammary Tissue ◽  
Limiting Factor ◽  
Elongation Factor 2 ◽  
High Level

The amount of protein synthesis translational elongation factor 2 (eEF-2) was estimated employing diphtheria toxin-dependent ADP-ribosylation in samples prepared from small amounts of tissue from mammary gland, skeletal muscle and liver from lactating dairy cows. A very high level of ADP-ribosylatable eEF-2 was found in mammary gland, amounting to 20-times the level found in liver and 50-times the level found in skeletal muscle. This obviously reflects the high protein synthesis activity in mammary tissue. To our knowledge, similar high activities have previously been reported only for cancer cells. A close linear relationship was found between the amount of diphtheria-toxin catalysed ADP-ribosylated eEF-2 and protein and casein output in milk from cows in late lactation. This strongly suggests that eEF-2 may be a limiting factor in milk protein synthesis.

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