Bariloche protein symposium argentine society for biochemistry and molecular biology

156
BIOCELL, 27 (Suppl. I), 2003
LI-P34.
MITOCHONDRIAL LIPID METABOLISMS IS AFFECTED
BY VITAMIN A DEFICIENCY IN HEART
Vega V, Gatica L, Bonomi M, Giménez MS and Oliveros LB.
Bioquímica Molecular
 
Univ. Nac. de San Luis. Chacabuco 917.
5700-San Luis. E-mail: [e-mail]
Introduction: We showed that vit A deficiency changes the lipid
compositions and decreases Acetyl CoA Carboxylase activity
(ACC) in heart. Now, the mitochondrial lipid compositions and
fatty acid (FA) 
β-oxidation is studied. Methods: Male Wistar rats
at 21 d age were weaned onto either a vit A deficient diet (-A) or
the same diet with 8 mg retinol/kg diet (control). They were fed
for 3 months. Mitochondrial lipids were quantified after separation
by TLC. Fatty acids were determined by GLC. Carnitine Palmitoyl
Transferase  activity (CPTI) was determined using 
[
3
H
]-carnitina.
Its short-term regulation was study with tetradecylglycidic acid
and malonyl-CoA as inhibitors and, the long-term regulation in
starved and starved + refeeded rats. Results: Mitochondrias of -A
rats showed: a decrease of cholesterol and cardiolipin; an increase
of sphingomielin, phosphatidic acid and lysophosphatidylcholine;
a  change in relative % of FA phospholipids: 16:0, 16:1, 18:0,
18:2, 20:4, 22:4; and an increase of FA 
β-oxidation. Conclusion:
Vit A deficiency would not affect the long-term regulation of CPTI,
but it would interfere with its short-term regulation and also
modified the mitochondrial lipid compositions.
LI-P35.
EFFECT OF HYPOTHYROIDISM ON GENES RELATED
TO CHOLESTEROL METABOLISM IN LIVER AND
HEART OF MOUSE
Lascano Cecilia, Gatica Laura, Álvarez Silvina and Giménez,
Sofía.
Bioquímica Molecular. Univ Nac San Luis. 5700 - San Luis.
Argentina. E-mail: [e-mail]
It is known that hypothyroidism condition produces several effects
on lipid metabolism. In the present work we studied biochemical
parameters of lipids and the expression of  SREBP-2, HMG CoA
Reductase and LDL Receptor genes. Male adult Balb/c mice
received 10 mg of Metimazol (Danantizol)/100 ml tap water by
30 days (HT group). Control mice received tap water without the
drug. Mice were killed by decapitation and blood and tissues were
collected. We measured total cholesterol (CT) in liver and heart
homogenates by Zak´s method. 1 
µg of RNA, extracted by TRIZOL
method, was transcribed to cDNA at 42°C using random hexamers
as primers and MMLV-RT (Moloney Murine Leukemia Virus).
Aliquots of 2 
µl of cDNA were used in the amplifications by PCR
using specific primers. Beta actin was used as an internal control.
In HT mice, CT of liver and heart increased in relation to control.
In liver, gene expression of SREBP-2 did not show any changes
while HMG CoA Reductase and LDL Receptor decreased. The
same situation was observed in heart.
With the dosis of Metimazol used, cholesterol metabolism is
affected in both organs.
LI-P36.
OSMOTIC RESPONSE OF LACTIC BACTERIA GROWN
AT DIFFERENT WATER ACTIVITIES
Emma E. Tymczyszyn, Diego Baez and E. Aníbal Disalvo.
Laboratorio de Fisicoquímica de Membranas Lipídicas y
Liposomas, Cátedra de Química General e Inorgánica, Facultad
de Farmacia y Bioquímica, Universidad de Buenos Aires.
The preservation of lactic bacteria for biotechnological purposes
by freezing or desiccation, produces a severe dehydration of the
cells causing irreversible damages at membrane level. The damage
affect the water and ionic permeability. As rehydration involves a
reincorporation of water to the cell, increasing their volume, the
permeability properties of the membrane can be measure by means
of the osmotic response of the bacteria. In this work we have
measure the osmotic response of bacteria grown in different water
activities and correlated its response with the changes in the lipid
composition and the probable presence of specific transport
molecules. The water permeability measured by changes in light
scattering was determined in a stopped-flow spectrometry. The
results indicate that bacteria grown at low water activities are
less permeable to water due to the increase in saturated fatty acids.
In addition, it was observed that part of the water flux may be
taking place through specific transport systems that are inhibit by
HgCl
2
LI-P37.
VOLTAMPEROMETRIC BEHAVIOUR OF MONOLAYERS
OF MIXTURES OF PHOSPHATIDYL CHOLINE AND
PHOSPHATIDYL ETHANOLAMINE ADSORBED ON
MERCURY
Almaleck SH
1
, Gordillo GJ
2
, and Disalvo EA.
1
1
Laboratorio de Fisicoquímica de Membranas Lipídicas, Facultad
de Farmacia y Bioquímica, UBA. Junín 956. Buenos Aires (1113).
2
DQIAQF, INQUIMAE, Facultad de Ciencias Exactas y Naturales,
UBA. C. Universitaria. Pabellón II. Buenos Aires (1428). E-mail:
[e-mail]
Monolayers of phospholipids adsorbed on mercury electrodes show
high mechanical stability, high resistance to electric fields and
may be well characterized through their capacity and voltammetric
responses. Previous works with pure PC and pure PE show specific
peaks that can be related with the type of molecular interactions
between the lipids in the  monolayer. The objective of this work is
to characterize the electrochemical behaviour of monolayers of
mixed phospholipids. We have applied the same methodology with
the purpose of investigating the response of monolayers composed
of different ratios of PC and PE. The results show that at 1:3 PE:PC
ratio the voltammograms are similar to those of pure PC. However
at the 1:1 ratio the peaks of PC are drastically reduced. On the
other hand the voltammograms of 3:1  PE:PC show the peaks of
PE slightly modified. Results are interpreted in terms of the specific
interactions between groups of the polar heads giving place to the
dynamical response of the monolayer structure.

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