scholarly journals Glutathione utilization by lactating bovine mammary secretory tissue in vitro

1981 ◽  
Vol 198 (1) ◽  
pp. 243-246 ◽  
Author(s):  
C R Baumrucker ◽  
P A Pocius ◽  
T L Riss
Keyword(s):  
Amino Acids ◽  
Milk Protein ◽  
Mammary Tissue ◽  
Mammary Cells ◽  
Tissue Uptake ◽  
Radioactive Label ◽  
Gamma Glutamyltransferase ◽  
Secretory Tissue ◽  
Glutamyl Transpeptidase

gamma-Glutamyltransferase (D-glutamyl transpeptidase, EC 2.3.2.2) activity has been shown to be located predominantly on the extracellular surface of the plasma membrane of lactating bovine mammary cells. Radioactive label from both oxidized ([14C]-gamma-glutamyl) and reduced ([35S]cysteinyl) glutathione was taken up and incorporated into acid-precipitable proteins of mammary tissue. Uptake was shown to involve the transport of free amino acids, and incorporation was shown to involve the action of gamma-=glutamyltransferase. These results indicate that lactating mammary tissue utilizes the constituent amino acids of glutathione for milk-protein synthesis.

Hormone-dependent milk protein gene expression in bovine mammary explants from biopsies at different stages of pregnancy

2004 ◽  
Vol 71 (2) ◽  
pp. 135-140 ◽  
Author(s):  
Paul A Sheehy ◽  
James J Della-Vedova ◽  
Kevin R Nicholas ◽  
Peter C Wynn
Keyword(s):  
Gene Expression ◽  
Milk Protein ◽  
Protein Gene ◽  
Bovine Milk ◽  
Mammary Tissue ◽  
Endocrine Regulation ◽  
Surgical Biopsy ◽  
Milk Protein Gene ◽  
Milk Protein Gene Expression

A method for the collection of mammary biopsies developed previously was refined and used to study the endocrine regulation of bovine milk protein gene expression. Our surgical biopsy method used real-time ultrasound imaging and epidural analgesia to enable recovery of a sufficient quantity of mammary tissue from late-pregnant dairy cows for explant culture in vitro. The time of biopsy was critical for prolactin-dependent induction of milk protein gene expression in mammary explants, as only mammary tissue from cows nearing 30 d prepartum was hormone-responsive. This suggests that during the later stages of pregnancy a change in the responsiveness of milk protein gene expression to endocrine stimuli occurred in preparation for lactation. This may relate to the diminution of a putative population of undifferentiated cells that were still responsive to prolactin. Alternatively, the metabolic activity of the tissue had increased to the level whereby the response of the tissue was no longer assessable using this model in vitro.

scholarly journals Nutritional availability of amino acids from protein cross-linked to protect against degradation in the rumen

1984 ◽  
Vol 52 (2) ◽  
pp. 239-247 ◽  
Author(s):  
John R. Ashes ◽  
Jim L. Mangan ◽  
Gurcharn S. Sidhu
Keyword(s):  
Amino Acids ◽  
Small Intestine ◽  
Medicago Sativa ◽  
Terminal Ileum ◽  
Milk Protein ◽  
The Other ◽  
Molar Basis ◽  
Lactating Goats ◽  
Total Milk

1. Casein was labelled with pairs of radioactive amino acids, lysine, tyrosine and leucine, one with I4C and the other with 3H, by jugular infusion into lactating goats followed by isolation of the double-labelled casein from the milk. Total milk protein was similarly labelled by jugular infusion of [35S]cystine. U-14C-labelled fraction- 1 leaf protein was isolated from lucerne (Medicago sativa) grown in an atmosphere of 14C022. The proteins were treated withdifferent levels(333 and667 mmol/kgprotein) offormaldehyde, glutaraldehyde and glyoxal.3. Absorption from the small intestine was measured in sheep with fistulas in the abomasum and terminal ileum, using Cr-EDTA as the digesta flow marker, by introducing radioactive casein into the abomasum.4. Lysine, tyrosine and cystine became increasingly unavailable for absorption from the small intestine of sheep with increasing levels of aldehyde. At the lower level (333 mmol/kg) the proportions of the amino acids that were unavailable were 0.192, 0.051 and 0.123 respectively. At the higher level of formaldehyde (667 mmol/kg) the corresponding values were 0.335, 0.201 and 0.432 respectively. Leucine was not made unavailable with formaldehyde.5. The proportions of lysine, tyrosine and leucine that were unavailable were higher, on a molar basis, after treatment of the proteins with the dialdehydes glutaraldehyde and glyoxal than after treatment with formaldehyde. However, the extent of protein protection provided by the dialdehydes in the rumen, measured using an in vitro procedure, was lower.

Production of free glutamate in milk requires the leucine transporter LAT1

2013 ◽  
Vol 305 (6) ◽  
pp. C623-C631 ◽  
Author(s):  
Takuya Matsumoto ◽  
Eiji Nakamura ◽  
Hidehiro Nakamura ◽  
Mariko Hirota ◽  
Ana San Gabriel ◽  
...  
Keyword(s):  
Amino Acids ◽  
Transport System ◽  
Active Role ◽  
Mammary Tissue ◽  
Limiting Factor ◽  
Mammary Cells ◽  
Oral Gavage ◽  
Uptake Inhibition ◽  
Umami Taste

The concentration of free glutamate (Glu) in rat's milk is ∼10 times higher than that in plasma. Previous work has shown that mammary tissue actively transports circulatory leucine (Leu), which is transaminated to synthesize other amino acids such as Glu and aspartate (Asp). To investigate the molecular basis of Leu transport and its conversion into Glu in the mammary gland, we characterized the expression of Leu transporters and [3H]Leu uptake in rat mammary cells. Gene expression analysis indicated that mammary cells express two Leu transporters, LAT1 and LAT2, with LAT1 being more abundant than LAT2. This transport system is sodium independent and transports large neutral amino acids. The Leu transport system in isolated rat mammary cells could be specifically blocked by the LAT1 inhibitors 2-aminobicyclo-[2.2.1]-heptane-2-carboxylic acid (BCH) and triiodothyronine (T3). In organ cultures, Glu secretion was markedly inhibited by these LAT1 inhibitors. Furthermore, the profiles of Leu uptake inhibition by amino acids in mammary cells were similar to those reported for LAT1. In vivo, concentrations of free Glu and Asp increased in milk by oral gavage with Leu at 6, 12, and 18 days of lactation. These results indicate that the main Leu transporter in mammary tissue is LAT1 and the transport of Leu is a limiting factor for the synthesis and release of Glu and Asp into milk. Our studies provide the bases for the molecular mechanism of Leu transport in mammary tissue by LAT1 and its active role on free Glu secretion in milk, which confer umami taste in suckling pups.

scholarly journals γ-Glutamyl Transpeptidase Inhibition Suppresses Milk Protein Synthesis in Isolated Ovine Mammary Cells

2004 ◽  
Vol 87 (2) ◽  
pp. 321-329 ◽  
Author(s):  
S.L. Johnston ◽  
K.E. Kitson ◽  
J.W. Tweedie ◽  
S.R. Davis ◽  
J. Lee
Keyword(s):  
Protein Synthesis ◽  
Milk Protein ◽  
Mammary Cells ◽  
Glutamyl Transpeptidase

Mechanism of glycine transport in mouse mammary tissue

2000 ◽  
Vol 67 (4) ◽  
pp. 475-483 ◽  
Author(s):  
GAYATRI REHAN ◽  
VINOD K. KANSAL ◽  
REKHA SHARMA
Keyword(s):  
Amino Acids ◽  
Isobutyric Acid ◽  
Pregnant Mouse ◽  
Mouse Mammary Gland ◽  
Mammary Tissue ◽  
Extracellular Medium ◽  
System A ◽  
Glycine Transport ◽  
Inhibition Analysis

The mechanism of glycine transport in lactating mouse mammary gland was investigated. Three Na+-dependent systems of glycine transport, distinguished on the basis of their ionic requirement and sensitivity to 2-(methylamino)isobutyric acid (MeAIB), were A (Na+-dependent, MeAIB-sensitive); (Na++Cl−)-dependent, MeAIB-insensitive; and Na+-dependent, Cl−-independent, MeAIB-insensitive. These systems were further distinguished on the basis of inhibition analysis and sensitivity to pH of the extracellular medium and preloading mammary tissue with amino acids. The uptake of glycine via the A system (Km 0·53 mM) was inhibited by preloading mammary tissue with alanine, while glycine uptake mediated by the (Na++Cl−)-dependent, MeAIB-insensitive system (Km 0·47 mM) was downregulated by preloading mammary tissue with all amino acids (alanine, sarcosine and histidine) tested. Treatment of mammary tissue with N-ethylmaleimide inhibited the uptake of glycine via both these systems. Decreasing the pH of the extracellular medium inhibited the uptake of glycine via the A system but not the (Na++Cl−)-dependent, MeAIB-insensitive system. On the basis of ionic requirement, system A appears to comprise two components, one dependent on Na+ plus Cl− and the other on Na+ alone. Insulin upregulated the A system-mediated uptake of glycine in pregnant mouse mammary tissue cultured in vitro, while the (Na++Cl−)-dependent, MeAIB-insensitive system remained unaffected.

scholarly journals Metabolism of l-(U-14C)valine, l-(U-14C)leucine, l-(U-14C)histidine and l-(U-14C) phenylalanine by the isolated perfused lactating guinea-pig mammary gland

1976 ◽  
Vol 156 (3) ◽  
pp. 553-560 ◽  
Author(s):  
S R Davis ◽  
T B Mepham
Keyword(s):  
Amino Acids ◽  
Guinea Pig ◽  
Milk Protein ◽  
Mean Transit Time ◽  
Mammary Tissue ◽  
Plasma Component ◽  
Ruminant Species ◽  
The Mean ◽  
Phenyl Alanine

1. The incorporation of L-[U-14C]leucine, L[U-14C]histidine and L-[U-14C]phenylalanine into casein secreted during perfusion of isolated guinea-pig mammary glands was demonstrated. 2. The extent of incorporation of label into casein residues was consistent with their being derived from free amino acids of the perfusate plasma. 3. The mean transit time of the amino acids from perfusate into secreted casein was approx. 100 min. 4. Whereas radioactive histidine and phenylalanine were incorporated solely into milk protein, radioactivity from [U-14C]valine was also transferred to CO2 and to an unidentified plasma component, and from [U-14C]leucine to plasma glutamic acid. 5. Evidence from experiments with [U-14C]phenylalanine suggests that, as in rats, but in contrast with ruminant species, guinea-pig mammary tissue does not possess phenyl alanine hydroxylase activity. 6. The results are discussed in relation to the possible role of essential amino acid catabolism in the control of milk-protein synthesis.

Abundance of solute carrier family 27 member 6 (SLC27A6) in the bovine mammary gland alters fatty acid metabolism

2021 ◽  
Author(s):  
Huimin Zhang ◽  
Ziliang Shen ◽  
Zhendong Yang ◽  
Hui Jiang ◽  
Shuangfeng Chu ◽  
...  
Keyword(s):  
Mammary Gland ◽  
Fatty Acid ◽  
Fatty Acid Metabolism ◽  
Acid Metabolism ◽  
Mammary Tissue ◽  
Mammary Cells ◽  
Solute Carrier Family ◽  
Bovine Mammary Gland ◽  
Solute Carrier

The Milk FA and transcriptome of bovine mammary tissue indicated that LCFA transport into mammary cells during late lactation. In vitro test underscored how FA transport via SLC27A6 could dictate the utilization of FA for TG synthesis versus oxidation.

Steps in amino-acid incorporation into mammary tissue

1958 ◽  
Vol 149 (936) ◽  
pp. 392-400 ◽  
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Mammary Gland ◽  
Amino Acid ◽  
De Novo ◽  
Protein Biosynthesis ◽  
Mammary Tissue ◽  
Mammary Cells ◽  
Intact Cells ◽  
Ideal System

The mammary gland in full lactation had for long been recognized as an ideal system for the study of the biosynthesis of protein. The discoveries during the last 5 years of the incorporation of labelled amino acids into the microsomes of cell homogenates and of other reactions of amino acids which might be on the pathway to protein synthesis, encouraged us to study the fate of amino acids in various systems prepared from mammary cells. De novo protein synthesis had not yet been proved in any system which contained no intact cells. So far no net increase in any defined protein fraction during incubations has been found or indeed looked for in our experiments. Naturally one hopes that such studies of the fate of labelled amino acids in cell-free preparations will reveal the detail of enzymic reactions which will prove to be part of the mechanisms of protein biosynthesis. Three types of reactions of amino acids in cell-free preparations from homogenates of many tissues have been studied most extensively. (1) The acyl activation of amino acids to form amino acid-acid adenylates in the presence of ATP and ‘activating enzymes’. (2) The formation of compounds of cell sap-ribonucleic acid ( SRN A ) with amino acids in the presence of ATP and ‘activating enzymes’. (3) The incorporation of amino acids into intracellular particles either from free amino acid or by transfer from amino-acid- SRN A compounds in the presence of ATP , guanosine triphosphate ( GTP ) and ‘activating enzymes’. In this paper we are giving a survey of the results of studies on these three types of reactions in systems prepared from mammary tissue and we are relating these to results obtained with other systems elsewhere. Some comparative studies of the incorporation of labelled amino acids into protein fractions of intact mammary cells (minced tissue) are also presented. All the original results given here were obtained from experiments with guinea-pig mammary gland preparations from animals 2 to 6 days after parturition. Experimental detail will be reported elsewhere.

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