scholarly journals The ribonucleic acids of the mammary gland of the guinea pig

1975 ◽  
Vol 146 (3) ◽  
pp. 575-583
Author(s):  
P Ashby ◽  
P N Campbell
Keyword(s):  
Mammary Gland ◽  
Guinea Pig ◽  
Gel Electrophoresis ◽  
Milk Protein ◽  
Polyacrylamide Gel Electrophoresis ◽  
Mammary Glands ◽  
Ribosomal Subunits ◽  
Ribonucleic Acids ◽  
Lactating Mammary Gland ◽  
Zone Velocity

1. 32-P-labelled polyribosome preparations were made from the mammary glands of lactating and late-pregnant guinea pigs after injection of (32-P)i into the animals. 2. The RNA of polyribosomes, ribosomal subunits and that released from polyribosomes by EDTA were analysed by zone velocity centrifugation and by polyacrylamide-gel electrophoresis. 3. RNA species which have the physical properties expected for the milk protein mRNA were detected. RNA species of a size which could code for the caseins were present in lactating but not in pre-lactating mammary-gland polyribosomes.

scholarly journals Glycoprotein synthesis in explants of developing rabbit mammary gland in culture

1981 ◽  
Vol 198 (3) ◽  
pp. 683-690 ◽  
Author(s):  
J P Bradshaw ◽  
D A White
Keyword(s):  
Mammary Gland ◽  
Gel Electrophoresis ◽  
Incubation Medium ◽  
Culture Medium ◽  
Soluble Fraction ◽  
Polyacrylamide Gel Electrophoresis ◽  
Mammary Glands ◽  
Peptide Backbone ◽  
Glycoprotein Synthesis ◽  
Lag Period

1. Explants of mammary glands of pregnant rabbits cultured in the absence of insulin, prolactin and cortisol incorporated [2-3H]mannose into lipid-linked mono- and oligo-saccharide and protein. 2. Inclusion of the hormones in the culture medium stimulated the incorporation of [2-3H]mannose into lipid-linked monosaccharide 4-fold, into lipid-linked oligosaccharide 4-fold and into protein 13-fold after 24 h in culture. 3. Addition of tunicamycin to the incubation medium completely inhibited the incorporation of [2-3H]mannose into lipid-linked oligosaccharide and protein after an initial lag period of about 2h. Incorporation of this radiolabel into lipid-linked monosaccharide was increased 4-fold under these conditions. 4. Incorporation of [4,5-3H]leucine into protein was unaffected by the presence of tunicamycin. 5. Analysis of mannose-labelled protein by polyacrylamide-gel electrophoresis indicated that a major radiolabelled protein of apparent mol.wt. 65,000-70,000 was synthesized and approx. 70% of this protein appeared in the soluble fraction. 6. Glycosylation of the protein but not synthesis of its peptide backbone was sensitive to tunicamycin. 7. Possible origins of this glycoprotein synthetized when the tissue is stimulated to differentiate in culture are discussed.

EFFECT OF LOCALLY IMPLANTED OESTROGEN ON THE RESPONSE OF THE RAT'S LACTATING MAMMARY GLAND TO OXYTOCIN

1973 ◽  
Vol 73 (4) ◽  
pp. 700-712 ◽  
Author(s):  
J. D. Bruce ◽  
X. Cofre ◽  
V. D. Ramirez
Keyword(s):  
Mammary Gland ◽  
Mammary Glands ◽  
Myoepithelial Cells ◽  
Recording System ◽  
Saline Infusion ◽  
High Dose ◽  
Low Doses ◽  
Milk Ejection ◽  
Lactating Mammary Gland ◽  
Small Rise

ABSTRACT On the day following delivery (day 1 of lactation) one abdominal mammary gland was implanted with oestrogen and the contralateral gland received an empty needle. At 2, 5 or 10 days of lactation the rats were anaesthetized with pentobarbital and the nipples of both abdominal glands were cannulated and their pressures recorded by means of transducers coupled to an amplifier and recording system. The normal mammary glands of 5-day lactating rats responded to very low doses of oxytocin (Syntocinon®, Sandoz) (5× 10−8 mU) with a rhythmic elevation in pressure. However, saline infusion also evoked a small rise in intra-mammary pressure. Earlier (2 days) and later (10 days) in lactation the responses were smaller. Oestrogen decreases significantly the milk ejection response to oxytocin, and the effect was maximal at day 10 of lactation. Histological observations confirmed the diminished reaction of the gland to oxytocin, since the milk was retained in the alveoli of rats bearing a mammary-oestrogen implant. A paradoxical rise in pressure was detected in normal as well as in oestrogen-implanted glands when the lowest dose of oxytocin was injected in lactating rats which had previously received a high dose of oxytocin (50 mU or 500 mU). These results reinforce the hypothesis that oestrogen alters the milk ejection response to oxytocin and that the mechanism is probably related to changes in the contractility of the myoepithelial cells.

Milk protein precursors in lactating goats

1992 ◽  
Vol 1992 ◽  
pp. 2-2 ◽  
Author(s):  
B J. Bequette ◽  
C. Backwell ◽  
G.E. Lobley ◽  
J.C. MacRae
Keyword(s):  
Mammary Gland ◽  
Dietary Fat ◽  
Nutritional Value ◽  
Milk Protein ◽  
Integrated Approach ◽  
Fat Intake ◽  
Lactating Goats ◽  
Lactating Mammary Gland ◽  
Milk Component ◽  
Kinetics Of

With the failure of current nutritional schemes for dairy ruminants to predict yields of milk and milk components, and perceptions of milk's nutritional value following recommendations to reduce dietary fat intake, an integrated approach to feeding and metabolism needs to be developed. Such a system must therefore be ‘metabolite’ based.An ability to predict changes in milk constituent output in response to alterations in nutrition requires, in the first instance, the identification of specific precursors for milk component synthesis in the lactating mammary gland. Arteriovenous differences across the mammary gland indicate that blood free amino acids (AA) are either taken-up by the gland in excess, equal to, or in insufficient amounts compared to their output in milk (1). Isotope labelling experiments have indicated that, in addition to AA free in blood, the mammary gland utilises a substantial amount of AA derived from constitutive mammary gland protein breakdown (2). The present experiment was designed to investigate the AA precursors and kinetics of milk protein synthesis and to confirm and extend the latter observations.

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.

scholarly journals Relative distribution of post-nuclear poly(A)-containing RNA abundance groups within the nuclear and post-nuclear polyadenylated and non-polyadenylated RNA populations of the lactating guinea-pig mammary gland

1980 ◽  
Vol 192 (2) ◽  
pp. 489-498 ◽  
Author(s):  
Ian C. Bathurst ◽  
Roger K. Craig ◽  
David G. Herries ◽  
Peter N. Campbell
Keyword(s):  
Mammary Gland ◽  
Guinea Pig ◽  
Milk Protein ◽  
Regulation Of Gene Expression ◽  
Milk Proteins ◽  
Relative Distribution ◽  
Free System ◽  
Low Salt ◽  
Nuclear Rna ◽  
System 2

1. RNA isolated from the post-nuclear supernatant of the lactating guinea-pig mammary gland was fractionated with oligo(dT)–cellulose into three populations; those that bound at ‘low salt’ [long poly(A) tracts, 78–32 nucleotides]; those that bound at ‘high salt’ [shorter poly(A) tracts, 48–21 nucleotides]; and those that did not bind [no poly(A) or short poly(A) tracts, <20 nucleotides]. Nuclear RNA was fractionated into two populations, those that bound in ‘low salt’ and those that did not bind. All the post-nuclear RNA fractions directed the synthesis of milk proteins in a Krebs II ascites cell-free system. 2. 3H-labelled DNA complementary to the post-nuclear poly-(A)-containing RNA population (low-salt fraction) was fractionated into abundant (milk-protein mRNA), moderately abundant and scarce sequences. This complementary DNA was then used to investigate the distribution of the mRNA sequences in the different RNA populations. This showed that all sequences were present in polyadenylated and non-polyadenylated fractions, but that major quantitative differences were apparent. The abundant milk-protein mRNA sequences predominated in the ‘low-salt’ post-nuclear poly(A)-containing RNA fraction, whereas the moderately abundant sequences predominated in the non-polyadenylated post-nuclear RNA fraction. In total cellular RNA, those sequences deemed initially to be moderately abundant within the ‘low-salt’ poly(A)-containing RNA population were present at a concentration very similar to those of the abundant milk-protein mRNA (approx. 6×105 copies of each sequence/cell). Similarly, analysis of the nuclear RNA populations showed that the ‘abundant’ and so-called ‘moderately abundant’ sequences were present in essentially identical concentrations (2×103 copies of each sequence/cell). The majority of these (90–95%) were non-polyadenylated. 3. The results are discussed in terms of the post-transcriptional mechanisms involved in the regulation of gene expression in the lactating guinea-pig mammary gland.

scholarly journals Molecular weight and subunit size of fatty acid synthetase from rabbit mammary gland

1976 ◽  
Vol 159 (1) ◽  
pp. 181-184 ◽  
Author(s):  
N Paskin ◽  
R J Mayer
Keyword(s):  
Molecular Weight ◽  
Mammary Gland ◽  
Fatty Acid ◽  
Sodium Dodecyl Sulphate ◽  
Gel Electrophoresis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Gel Filtration ◽  
Fatty Acid Synthetase ◽  
Subunit Size

Fatty acid synthetase purified from the mammary gland of the rabbit has a mol. wt. of 968000 as determined by gel filtration. The enzyme gave one band, corresponding to a mol.wt. of approx. 35000, on polyacrylamide-gel electrophoresis in the presence of sodium dodecyl sulphate and phenylmethanesulphonyl fluoride.

II. Mitt.: Auflösung der Chromoproteidfraktion aus Rattenleber-Ribosomen mit Hilfe der Polyacrylamidgel-Elektrophorese

1970 ◽  
Vol 25 (1) ◽  
pp. 67-72 ◽  
Author(s):  
Wolfram Domschke ◽  
Jürgen G. Meyer-Bertenrath
Keyword(s):  
Gel Electrophoresis ◽  
Ribosomal Proteins ◽  
Polyacrylamide Gel Electrophoresis ◽  
Gel Filtration ◽  
The Other ◽  
Blue Staining ◽  
Ribosomal Subunits ◽  
Molecular Weights ◽  
The One ◽  
Liver Ribosomes

After preparation of a coloured protein component containing iron from rat liver ribosomes 1 this fraction was submitted to detailed analysis by means of polyacrylamide gel electrophoresis. Thus it may be separated into one main and two secondary bands, which do not contain RNA detectable by methylene blue staining. The ferric content of all bands can be demonstrated by staining with 2,4-dinitroso-1,3-naphthalenediol 2. These bands are to be found in the large ribosomal subunits as well as in the small one in qualitative conformity, they differ, however, in their quantitative relations to each other depending on origin. LiCl-extraction as described for the preparation of ribosomal proteins causes dissociation of the chromoproteid fraction into six bands possessing lower molecular weights each than the original bands.The chromoproteids, localized in the large ribosomal subunits on the one hand and in the small subunits on the other hand were prepared differentiatedly by gel filtration. Results show the chromoproteid represented in the 57-S-subunit on a bigger scale than the nucleoproteid part, on the contrary, the 29-S-subunit is constructed of RNA-containing material preferably.

scholarly journals The formation of lipid-linked sugars by cell-free preparations of lactating rabbit mammary gland

1978 ◽  
Vol 170 (3) ◽  
pp. 479-486 ◽  
Author(s):  
D A White
Keyword(s):  
Mammary Gland ◽  
Acid Hydrolysis ◽  
Alkaline Hydrolysis ◽  
Gel Electrophoresis ◽  
Incubation Medium ◽  
Polyacrylamide Gel Electrophoresis ◽  
Protein Fractions ◽  
Exogenous Substrate ◽  
Major Species ◽  
Hydrolysis Of

1. A lactating rabbit mammary-gland microsomal system catalysed the incorporation of mannose from GDP-[U-14C]mannose into three endogenous acceptors, (i) polyprenyl phosphate mannose, (ii) lipid-linked oligosaccharide and (iii) protein. 2. Synthesis of polyprenyl phosphate mannose was stimulated by addition of dolichol phosphate to the incubation medium and was reversed by addition of GDP. The product had properties identical with those of authentic dolichol phosphate mannose. 3. The oligosaccharides derived from acid hydrolysis of the lipid-linked oligosaccharide fraction were of six, eight and nine to ten monosaccharide units, the octasaccharide being the major species formed. The oligosaccharide appeared to be attached to the lipid via a pyrophosphate bridge, since strong alkaline hydrolysis liberated an oligosaccharide phosphate. 4. Polyprenyl phosphate mannose served as a mannose donor to lipid-linked oligosaccharides and protein. When added as exogenous substrate it gave rise to a lipid-linked oligosaccharide of about six units. 5. Incorporation of radioactivity in protein was low, but polyacrylamide-gel electrophoresis of the protein fractions indicated that polypeptides of mol.wts. 115000, 75000 and 33000 were labelled.

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