scholarly journals Mechanisms of hepatic phosphatidylcholine synthesis in the developing guinea pig: contributions of acyl remodelling and of N-methylation of phosphatidylethanolamine

1993 ◽  
Vol 290 (1) ◽  
pp. 67-73 ◽  
Author(s):  
G C Burdge ◽  
F J Kelly ◽  
A D Postle
Keyword(s):  
Fatty Acids ◽  
Guinea Pig ◽  
Molecular Species ◽  
Essential Fatty Acids ◽  
Specific Radioactivity ◽  
Long Chain Fatty Acids ◽  
Radioactivity Analysis ◽  
Species Specific ◽  
Phosphatidylcholine Synthesis

Hepatic phosphatidylcholine (PC) from the immature fetal guinea pig at day 55 of gestation comprised mainly unsaturated molecular species containing C18:2(n-6) and C22:6(n-3) at the sn-2 position, reflecting placental permeability to essential fatty acids. At both day 55 and term (day 68), [Me-14C]choline was incorporated in utero over 3 h largely into sn-1-C16:0 PC species, with incorporation into sn-1-C18:0 PC species increasing by 18 h of incubation. Comparison of specific radioactivities after 3 h and 18 h suggests PC acyl remodelling by phospholipase A1. No incorporation into C20:4(n-6)-containing PC species could be detected of either [Me-14C]choline in vivo or CDP-[Me-14C]choline in isolated microsomes. The major phosphatidylethanolamine (PE) species were 16:0/22:6 and 18:0/22:6. Although [14C]ethanolamine was initially incorporated mainly into sn-1-C16:0 species, specific-radioactivity analysis suggested differential turnover rather than acyl remodelling. [1,2-14C]Ethanolamine and [Me-14C]methionine incorporation into PC molecular species indicated that both newly synthesized and total PE pools were available for N-methylation. Since the PC pool synthesized from PE included C20:4- and C22:6-containing species, N-methylation may provide a mechanism for supplying essential long-chain fatty acids to developing tissues that can be regulated independently from bulk PC synthesis.

scholarly journals The pattern of fatty acid synthesis in lactating rabbit mammary gland studied in vivo

1972 ◽  
Vol 126 (4) ◽  
pp. 1005-1007 ◽  
Author(s):  
E. M. Carey ◽  
R. Dils
Keyword(s):  
Fatty Acids ◽  
Mammary Gland ◽  
Fatty Acid ◽  
Chain Length ◽  
Specific Radioactivity ◽  
Acid Uptake ◽  
Long Chain Fatty Acids ◽  
Long Chain ◽  
Chain Fatty Acids

The biosynthesis of fatty acids has been studied in lactating rabbits at 6h after intravenous injection of sodium [1-14C]acetate. The specific radioactivities of the individual fatty acids (C6:0 to C14:0) and the proportions of these fatty acids synthesized were similar in mammary tissue and milk. Hexanoic acid had the highest specific radioactivity, and the C8:0–C14:0 fatty acids had similar specific radioactivities, which were about five times those of C16 and C18 acids. No radioactivity was detected in fatty acids of chain length <C14 in the liver, blood or adipose tissue and the specific radioactivities of fatty acids of chain length >C14 in these tissues were similar to those of the long-chain fatty acids in the milk and mammary gland. The results show that the C4:0–C14:0 fatty acids are synthesized within the mammary gland rather than by fatty acid uptake from circulating blood or by oxidation of long-chain fatty acids within the gland. We conclude that de novo synthesis of esterified fatty acids in vivo by this tissue has a high degree of chain-length specificity.

scholarly journals Evidence for the regulation of guinea-pig heart microsomal phosphatidylcholine-hydrolysing phospholipase A1 by guanosine 5′-[γ-thio]triphosphate

1992 ◽  
Vol 288 (3) ◽  
pp. 965-968 ◽  
Author(s):  
K Badiani ◽  
X Lu ◽  
G Arthur
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Guinea Pig ◽  
Molecular Species ◽  
Inhibitory Effect ◽  
Phospholipase A1 ◽  
Guinea Pig Heart ◽  
Substrate Specificities ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

We have recently characterized lysophospholipase A2 activities in guinea-pig heart microsomes and postulated that these enzymes act sequentially with phospholipases A1 to release fatty acids selectively from phosphatidylcholine (PC) and phosphatidylethanolamine, thus providing an alternative route to the phospholipase A2 mode of release. In a further investigation of the postulated pathway, we have characterized the PC-hydrolysing phospholipase A1 in guinea-pig heart microsomes. Our results show that the enzyme may have a preference for substrates with C16:0 over C18:0 at the sn-1 position. In addition, although the enzyme cleaves the sn-1 fatty acid, the rate of hydrolysis of PC substrates with C16:0 at the sn-1 position was influenced by the nature of the fatty acid at the sn-2 position. The order of decreasing preference was C18:2 > C20:4 = C18:1 > C16:0. The hydrolyses of the molecular species were differentially affected by heating at 60 degrees C. An investigation into the effect of nucleotides on the activity of the enzyme showed that guanosine 5′-[gamma-thio]triphosphate (GTP[S]) inhibited the hydrolysis of PC by phospholipase A1 activity, whereas GTP, guanosine 5′-[beta-thio]diphosphate (GDP[S]), GDP, ATP and adenosine 5′-[gamma-thio]triphosphate (ATP[S]) did not affect the activity. The inhibitory effect of GTP[S] on phospholipase A1 activity was blocked by preincubation with GDP[S]. A differential effect of GTP[S] on the hydrolysis of different molecular species was also observed. Taken together, the results of this study suggest the presence of more than one phospholipase A1 in the microsomes with different substrate specificities, which act sequentially with lysophospholipase A2 to release linoleic or arachidonic acid selectively from PC under resting conditions. Upon stimulation and activation of the G-protein, the release of fatty acids would be inhibited.

scholarly journals DISTRIBUTION OF NEWLY SYNTHESIZED AMYLASE IN MICROSOMAL SUBFRACTIONS OF GUINEA PIG PANCREAS

1966 ◽  
Vol 30 (3) ◽  
pp. 519-530 ◽  
Author(s):  
P. Siekevitz ◽  
G. E. Palade
Keyword(s):  
Guinea Pig ◽  
High Speed ◽  
Specific Activity ◽  
Specific Radioactivity ◽  
Enzymic Activity ◽  
Pellet Fraction ◽  
Light Region ◽  
Centrifuge Tube ◽  
In Vivo Labeling

Amylase distribution was studied in guinea pig pancreas microsomes fractionated by centrifuging, for 2 hr at 57,000 g in a linear 10 to 30% sucrose gradient, a resuspended high speed pellet obtained after treating microsomes with 0.04% deoxycholate (DOC).1 Amylase appeared in the following positions in the gradient: (a) a light region which contained ∼35% of total enzymic activity and which coincided with a monomeric ribosome peak; (b) a heavy region which contained ∼10% of enzymic activity in a sharp peak but which had very little accompanying OD260 absorption; (c) a pellet at the bottom of the centrifuge tube which contained ∼20% of the enzymic activity. After 5 to 20 min' in vivo labeling with leucine-1-C14, radioactive amylase was solubilized from these three fractions by a combined DOC-spermine treatment and purified by precipitation with glycogen, according to Loyter and Schramm. In all cases, the amylase found in the pellet had five to ten times the specific activity (CPM/enzymic activity) of the amylase found in the light or heavy regions of the gradient. The specific radioactivity (CPM/mg protein) of the proteins or peptides not extracted by DOC-spermine was similar for all three fractions. Hypotonic treatment of the fractions solubilized ∼80% of the total amylase in the fraction from the heavy region of the gradient, but only ∼20% of the amylase in the monomer or pellet fraction. Electron microscope observation indicates that the monomer region of the gradient contained only ribosomes, that the heavy region of the gradient contained small vesicles with relatively few attached ribosomes, and that the pellet was composed mostly of intact or ruptured microsomes with ribosomes still attached to their membranes. It is concluded from the above, and from other evidence, that most of the amylase activity in the monomer region is due to old, adsorbed enzyme; in the heavy region mostly to enzyme already inside microsomal vesicles; and in the pellet to a mixture of newly synthesized and old amylase still attached to ribosomes. Furthermore, the ribosomes with nascent, finished protein still bound to them are more firmly attached to the membranes than are ribosomes devoid of nascent protein.

scholarly journals The occurrence of polyenoic very long chain fatty acids with greater than 32 carbon atoms in molecular species of phosphatidylcholine in normal and peroxisome-deficient (Zellweger's syndrome) brain

1988 ◽  
Vol 253 (3) ◽  
pp. 645-650 ◽  
Author(s):  
A Poulos ◽  
P Sharp ◽  
D Johnson ◽  
C Easton
Keyword(s):  
Fatty Acids ◽  
Molecular Species ◽  
Carbon Chain ◽  
Normal Brain ◽  
Long Chain Fatty Acids ◽  
Brain Physiology ◽  
Chain Lengths ◽  
The Brain ◽  
Long Chain ◽  
Chain Fatty Acids

The n-6 tetra- and pentaenoic fatty acids with carbon chain lengths greater than 32 found in normal brain are located predominantly in a separable species of phosphatidylcholine. A similar phospholipid is found in increased amounts in the brain of peroxisome-deficient (Zellweger's syndrome) patients, but the fatty acid composition differs in that penta- and hexaenoic derivatives predominate. Our data strongly suggest that the polyenoic very long chain fatty acids are confined to the sn-1 position of the glycerol moiety, while the sn-2 position is enriched in saturated, monounsaturated and polyunsaturated fatty acids with less than 24 carbon atoms. It is postulated that these unusual molecular species of phosphatidylcholine may play some, as yet undefined, role in brain physiology.

scholarly journals Fattening rabbits in mobile arks: effect of housing system on in vivo oxidative status and meat quality

2016 ◽  
Vol 24 (4) ◽  
pp. 303 ◽  
Author(s):  
S. Mattioli ◽  
M. Martino ◽  
S. Ruggeri ◽  
V. Roscini ◽  
L. Moscati ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Polyunsaturated Fatty Acids ◽  
Meat Quality ◽  
Essential Fatty Acids ◽  
Quality Parameters ◽  
Oxidative Status ◽  
Housing System ◽  
Longissimus Lumborum

<p>The aim of this trial was to study the effect of an alternative housing system on the oxidative status and meat quality of fattening rabbits. From May to June 2014, 60 rabbits of 35 d of age were reared in Mobile Arks (MA) placed on alfalfa grass and frequently moved for 40 d. To assess the health status of animals, blood samples were collected at slaughter in MA and in conventional cages (C). Meat quality parameters were also evaluated. Concerning the <em>in vivo </em>oxidative status, ark-reared rabbits showed higher thiobarbituric reactive substances values than C ones, probably for the higher motor activity due to the larger living area. The lipid percentage of <em>Longissimus lumborum </em>muscle was lower (1.22 <em>vs. </em>1.48%) in the ark group. There were no significant differences in the muscle pH, colour, water holding capacity and cooking loss. Given the higher intake of grass, rich in vitamins, carotenes, polyphenols and polyunsaturated fatty acids, the antioxidant content of meat was higher in ark-reared rabbits (7.42 <em>vs. </em>6.82 µg/g of retinol, 719.2 <em>vs. </em>683.3 ng/g of α-tocopherol, respectively). Even the fatty acid profile of MA rabbits reflected the higher intake of essential fatty acids from grass and the n-3 long chain polyunsaturated fatty acids (arachidonic acid, eicosapentaenoic acid and docosahexaenoic acid) were almost doubled. Our study suggested that the fattening of rabbits in ark system could be a possible alternative system to improve the meat quality of rabbits.</p><p><strong><br /></strong></p>

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