scholarly journals The protein-synthesizing activity of ribosomes isolated from the mammary gland of lactating and pregnant guinea pigs

1971 ◽  
Vol 123 (5) ◽  
pp. 865-874 ◽  
Author(s):  
E. Fairhurst ◽  
Diana McIlreavy ◽  
P. N. Campbell
Keyword(s):  
Protein Synthesis ◽  
Mammary Gland ◽  
Guinea Pig ◽  
Guinea Pigs ◽  
Cyanogen Bromide ◽  
Mammary Glands

1. Polyribosome preparations were made from the deoxycholate-treated post-nuclear fractions obtained by the disruption of mammary glands from lactating and pregnant guinea pigs. 2. A high proportion of large polyribosomes was obtained from the glands of lactating animals whereas mainly small polyribosomes were obtained from the glands of pregnant animals. The isolated preparations incorporated [14C]phenylalanine into protein. The polyribosomes from the glands of pregnant animals were less active than those from the glands of lactating animals but the activity of the former was stimulated more by poly(U) than was the latter. 3. The ribosomes from mammary gland could be dissociated into subunits after incubation, under conditions necessary for protein synthesis, in the presence of puromycin. The subunits could be recombined to give a preparation that actively polymerized [14C]phenylalanine in the presence of poly(U). The subunits from guinea-pig mammary gland could be combined with subunits from liver of either guinea pig or rat. Hybrid ribosomes were also formed from subunits derived from glands of pregnant and lactating animals. The hybrids were as active as were the ribosomes formed by reassociation of subunits from the same tissue, suggesting that in this respect the ribosomes from pregnant animals were not defective. 4. Polyribosomes from mammary glands of lactating animals when incubated with cell sap from the same source were tested for their ability to synthesize α-lactalbumin. The polyribosomes were incubated in the presence of [3H]leucine and α-lactalbumin was isolated from the supernatant. The protein was finally treated with cyanogen bromide and the C-terminal and N-terminal fragments were separated and their radioactivity was determined. Both fragments were radioactive consistent with the synthesis of α-lactalbumin. 5. The results are discussed in relation to protein synthesis in the mammary gland after parturition.

On a Peculiar Type of Intersexuality in the Guinea-Pig

1927 ◽  
Vol 4 (3) ◽  
pp. 227-244
Author(s):  
ALEXANDER LIPSCHUTZ
Keyword(s):  
Guinea Pig ◽  
Guinea Pigs ◽  
Mammary Glands ◽  
The Other ◽  
Normal Male ◽  
Normal Female ◽  
Sexual Hormones ◽  
Testicular Transplantation ◽  
Hereditary Nature ◽  
External Genital Organs

An abnormal condition of the external genital organs in 16 otherwise normal female guinea-pigs is described. They possessed an hypertrophied penis-like clitoris and horny styles similar to those in the intromittent sac of the normal male penis. The abnormalities are often asymmetrical, the clitoris and the horny style on one side being more developed than on the other. They may even be absent on one side. It is suggested that the malformation is a peculiar type of "partial somatic intersexuality," the external genital organs resembling those in the male guinea-pig. The condition is identical with that described in the castrated female guinea-pig experimentally masculinised by testicular transplantation. There was no indication of the ovaries producing simultaneously female and male sexual hormones: (a) The ovaries were histologically normal. (b) The ovaries when engrafted into castrated males produced the typical female hormonic effect on the mammary glands and had no influence on the penis or on the horny styles. (c) The clitoris and the horny styles of the intersexual females were not affected by removal of the ovaries, whereas in the male removal of the testes caused a pronounced regression of the horny styles even in fully grown animals. (d) The horny styles when cut regenerated even after removal of the ovaries; there is never a regeneration in the castrated male, but only in the normal male. The question is discussed whether the described type of intersexuality might be a case of "successive hormonic intersexuality," both kinds of sexual hormones having been produced simultaneously for a certain time whereas at a later stage only female hormones were secreted. The hypertrophied clitoris and the horny styles would then be considered as "fixed" sex characters persisting after the disappearance of the male sexual hormones. The problem of fixation of sex characters by sexual hormones is considered on experimental lines. The facts observed are rather against the suggestion that the intersexuality described is a case of successive hormonic intersexuality. Other possibilities of explaining the morphogenetic basis of this peculiar type of intersexuality are also discussed. The intersexuality described is of an hereditary nature.

THE IN VITRO METABOLISM OF MAMMARY GLAND SLICES IN THE PRESENCE OF POSTERIOR PITUITARY LOBE EXTRACTS RICH IN MELANOPHORE-DISPERSING ACTIVITY

1957 ◽  
Vol 15 (4) ◽  
pp. 366-373 ◽  
Author(s):  
T. R. BRADLEY ◽  
G. M. MITCHELL
Keyword(s):  
Mammary Gland ◽  
Guinea Pigs ◽  
Incubation Medium ◽  
Mammary Glands ◽  
Gas Evolution ◽  
Early Lactation ◽  
Posterior Pituitary ◽  
Rats And Mice ◽  
Posterior Pituitary Lobe

SUMMARY Slices cut from mammary glands of rats and mice during gestation and lactation were incubated in vitro in the presence of pig posterior pituitary lobe extracts rich in melanophore-dispersing ('B') activity. Slices taken in early lactation but not during gestation or late lactation showed increased net gas evolution compared with control slices. Similar tissue from rabbits and guinea-pigs did not give rise to this effect, nor did slices of other tissues taken from lactating rats. The increased net gas evolution was not observed in the absence of glucose from the incubation medium. Treatment of the 'B' extract with NaOH or hypophysectomy of the rats prior to use decreased the response.

scholarly journals Utilization of l-alanine and l-glutamine by lactating mammary gland of the rat. A role for l-alanine as a lipogenic precursor

1981 ◽  
Vol 196 (3) ◽  
pp. 757-762 ◽  
Author(s):  
J R Viña ◽  
D H Williamson
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Mammary Gland ◽  
Pyruvate Dehydrogenase ◽  
Blood Concentration ◽  
Mammary Glands ◽  
Cafeteria Diet ◽  
Arterial Blood ◽  
Lactating Mammary Gland

1. Lactation is associated with an increase in the arterial blood concentration of L-alanine and L-glutamate, but a decrease in that of L-glutamine compared with the corresponding values for virgin rats. 2. Virgin rats fed a ‘cafeteria diet’ that induces hyperphagia have increased arterial concentrations of L-alanine, L-glutamate and L-glutamine. During lactation L-alanine and L-glutamate concentrations are even higher. 3. The removal of L-alanine is decreased in hepatocytes from lactating rats fed either a chow or cafeteria diet. 4. Measurements of arteriovenous differences across lactating mammary glands indicate that appreciable amounts of L-glutamine and L-alanine are extracted by the gland. 5. A high proportion of the L-alanine metabolized by isolated acini from fed lactating rats is converted into lipid. 6. Metabolism of L-alanine in acini from starved lactating rats is limited by the activity of pyruvate dehydrogenase. 7. It is concluded that L-alanine and certain other amino acids taken up by the gland in excess of the requirements for protein synthesis can be converted into lipid.

THE EFFECT OF OESTRONE ON THE MAMMARY GLAND OF ADRENALECTOMIZED GUINEA-PIGS

1957 ◽  
Vol 16 (2) ◽  
pp. 227-NP ◽  
Author(s):  
E. O. HÖHN
Keyword(s):  
Mammary Gland ◽  
Guinea Pig ◽  
Adrenal Cortex ◽  
Guinea Pigs ◽  
Growth Response ◽  
Alcoholic Solution ◽  
Survival Period ◽  
Alveolar Development ◽  
Average Survival

SUMMARY In the guinea-pig progesterone is not required for alveolar development of the mammary gland. In order to test the hypothesis that this can be accounted for by endogenous progesterone produced by the adrenal cortex in this species, the growth response of the mammary gland to oestrone of adrenalectomized castrated male guinea-pigs has been studied. Oestrone applied to the nipples as an alcoholic solution in doses of 15 μg/day for 14 days resulted in the formation of clusters of mammary alveoli in animals subjected merely to castration. In eleven castrated and adrenalectomized animals which survived oestrone treatment for periods of 11–28 days only duct proliferation with occasional formation of isolated alveoli was observed. Nipple growth in response to oestrone, as indicated by changes in nipple length, was much the same in both groups. Administration of oestrone to adrenalectomized animals was found to be toxic. The average survival of oestrone-treated, adrenalectomized castrated animals was only 4 days, compared with an average survival period of 16·6 days in similar animals not treated with oestrone.

Effects of increased supply of essential amino acids on the metabolism of the isolated perfused guinea-pig mammary gland

1979 ◽  
Vol 46 (1) ◽  
pp. 59-67 ◽  
Author(s):  
Andrew R. Peters ◽  
Stephen Alexandrov ◽  
T. Ben Mepham
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Mammary Gland ◽  
Amino Acid ◽  
Guinea Pig ◽  
Amino Acid Uptake ◽  
Essential Amino Acids ◽  
Acid Uptake ◽  
Isoleucine Leucine ◽  
Group 1

SUMMARYThe effects of high rates of infusion of essential amino acids on amino acid uptake by the isolated perfused guinea-pig mammary gland were studied. Infusion of methionine, tyrosine, phenylalanine, histidine and tryptophan (designated group 1) resulted in significant increases in the uptakes of tyrosine, phenylalanine and histidine. Methionine, tryptophan and other essential amino acids were not significantly affected. Infusion of threonine, valine, isoleucine, leucine, lysine and arginine (designated group 2) resulted in significant increases in uptake of all these amino acids. Group 1 amino acid uptake was not significantly affected. Infusion of all the essential amino acids (i.e. groups 1 and 2 together) resulted in significant increases in all their uptakes. Using as index ‘the predicted rate of protein synthesis’, infusion of group 1 and 2 together led to an apparent 27% increase in protein synthesis. The above results are discussed in relation to the control of milk protein synthesis by limiting essential amino acids.

Metabolism of leucine by the isolated perfused goat udder

1983 ◽  
Vol 50 (4) ◽  
pp. 413-424 ◽  
Author(s):  
Eddy Roets ◽  
Anne-Marie Massart-Leën ◽  
Georges Peeters ◽  
Roger Verbeke
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Mammary Gland ◽  
Milk Protein ◽  
Lipid Synthesis ◽  
Mammary Glands ◽  
Plasma Leucine ◽  
Free Plasma ◽  
Casein Synthesis

SUMMARYSeven lactating goat mammary glands from 6 goats were perfused for several hours in the presence of [U-14C]L-leucine (4 experiments) or [2-3H; l-14C]DL-leucine (3 experiments) and received adequate quantities of glucose, acetate and amino acids. Radioactivity in casein was mainly recovered in leucine and 90% of casein leucine was derived from free plasma leucine. About 64% of the leucine molecules were used for casein synthesis. Up to 12% of the molecules were channelled into lipid synthesis, while the remaining (up to 24%) were metabolized to CO2. From the 3H/14C ratio of casein and casein leucine, it was calculated that 70–80% of the leucine molecules were reversibly transaminated before their incorporation into milk protein. However, only 4–8% of the plasma leucine molecules were transaminated during passage through the udder. Different pools for oxidation and for protein synthesis may be present in the goat mammary gland.

scholarly journals Guinea-pig milk-protein synthesis. Isolation and characterization of messenger ribonucleic acids from lactating mammary gland and identification of caseins and pre-α-lactalbumin as translation products in heterologous cell-free systems

1976 ◽  
Vol 160 (1) ◽  
pp. 57-74 ◽  
Author(s):  
R K Craig ◽  
P A Brown ◽  
O S Harrison ◽  
D McIlreavy ◽  
P N Campbell
Keyword(s):  
Molecular Weight ◽  
Protein Synthesis ◽  
Mammary Gland ◽  
Guinea Pig ◽  
Wheat Germ ◽  
Milk Proteins ◽  
N Terminus ◽  
Lactating Mammary Gland ◽  
Heterologous Cell ◽  
Alpha Lactalbumin

1. The major milk proteins synthesized by the lactating mammary gland of the guinea pig were identified and designated as caseins A, B and C and alpha-lactalbumin, with estimated mol.wts. of 28000, 25500, 20500 and 14500 respectively. 2. Antisera to the total casein fraction and to alpha-lactalbumin were prepared from rabbits. The milk proteins were also iodinated with either 131I or 125I. 3. A poly(A)-rich RNA fraction was isolated from lactating guinea-pig mammary glands. Isolation was by affinity chromatography on oligo(dT)-cellulose. 4. Examination of this RNA fraction by electrophoresis on polyacrylamide gels containing formamide indicated three major species 1, 2 and 3, with estimated wol.wts. of 5.4 × 10(5) and 3.3 × 10(5), and the apparent absence of rRNA species. 5. The poly(A)-rich RNA stimulated protein synthesis in heterologous cell-free systems based on wheat germ, Krebs II ascites-tumour cells, and the latter supplemented with an initiation factor-3 fraction from rabbit reticulocyte ribosomes. 6. Between 80 and 90% of the protein synthesis directed by the mRNA was for milk proteins. 7. Analysis of the proteins immunoprecipitated by the alpha-lactalbumin antiserum showed in the wheat-germ system that the product was a protein with a molecular weight greater than that of alpha-lactalbumin, whereas in the ascites-tumour-cell systems both this protein and alpha-lactalbumin were found. When the larger protein was treated with CNBr and the resulting peptides were examined, it was shown that the extra peptide was at the N-terminus. This and other evidence is adduced for the initial translation product of alpha-lactalbumin being a precursor with an addition of about ten amino acids at the N-terminus. 8. Similar analysis of the casein immlnospecific proteins produced under the direction of mRNA indicated that the products had a molecular weight that was apparently a littel smaller than that of the caseins synthesized in vivo. This was not consistent with higher-molecular weight casein precursors. 9. Possible explanations for the results obtained are discussed, especially in terms of the physiological significance of the pre-alpha-lactalbumin as a secretory protein.

Acetate utilization by the isolated perfused guinea-pig mammary gland

1976 ◽  
Vol 43 (2) ◽  
pp. 197-203 ◽  
Author(s):  
T. B. Mepham ◽  
S. R. Davis ◽  
J. R. Humphreys
Keyword(s):  
Fatty Acids ◽  
Mammary Gland ◽  
Guinea Pig ◽  
Blood Concentration ◽  
Mammary Glands ◽  
Acetate Concentration ◽  
Physiological Range ◽  
Acetate Uptake ◽  
Acetate Utilization ◽  
The Mean

SummaryAcetate uptake by isolated perfused guinea-pig mammary glands was approximately l·0 mg g−1 h−1 when perfusate acetate concentrations were in the physiological range (5–11 mg/100 ml plasma). At perfusate concentrations below this range (mean 3·62 mg/100 ml plasma) the uptake was not significantly different, but in one experiment in which the mean acetate concentration was 14·5 mg/100 ml plasma the uptake was markedly elevated. Radioactivity from Na [1-14C]acetate was incorporated into CO2 and milk and tissue fat, being largely present in C16 and C18 fatty acids. The guinea-pig is atypical of non-ruminants and similar to ruminants in respect of the blood concentration and mammary utilization of acetate.

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 Esterification of glycerol 3-phosphate in lactating guinea-pig mammary gland

1967 ◽  
Vol 105 (1) ◽  
pp. 213-223 ◽  
Author(s):  
N. J. Kuhn
Keyword(s):  
Mammary Gland ◽  
Guinea Pig ◽  
Phosphatidic Acid ◽  
Guinea Pigs ◽  
Particulate Fraction ◽  
Mammary Tissue ◽  
Acyl Donor ◽  
Free System ◽  
Kennedy Pathway ◽  
A Cell

1. The presence of palmitoyl-CoA–l-glycerol 3-phosphate palmitoyltransferase (EC 2.3.1.15) has been demonstrated in a particulate fraction of mammary tissue from lactating guinea pigs. 2. Cell-free preparations also catalysed the activation of palmitate and oleate, and the conversion of enzymically formed phosphatidic acid into glycerides, in accord with the Kennedy pathway of glyceride formation. 3. The properties of the system that esterifies l-glycerol 3-phosphate were studied with respect to substrates and cofactors, and the reaction product was shown to be phosphatidic acid (1,2-diacyl glycerol 3-phosphate). 4. The extent to which newly formed phosphatidic acid was converted into glyceride in a cell-free system was dependent on the nature of the acyl donor, the concentration of subcellular particles, the time of incubation and the concentration of Mg2+.

Sign in / Sign up

Export Citation Format

Share Document