Differential effect of dietary fat saturation and cholesterol on hepatic apolipoprotein gene expression in rats.

The effects of dietary cholesterol and fat saturation on hepatic apolipoprotein A-I, A-II, A-IV, B, C-I, C-III, E and LDL receptor mRNA levels were studied in male rats. Animals were maintained for 2 months on a high fat diet (40% w/w) containing 0.1% cholesterol. Two groups of control animals received either chow diet or chow plus 0.1% cholesterol, while experimental groups received as their fat supplement coconut, corn or olive oil. Olive oil fed animals had higher levels of hepatic apo A-I than the control cholesterol group (1.6 +/- 0.3 vs. 0.8 +/- 0.2). Apo E mRNA levels were 50% and 72% higher in animals consuming the saturated (coconut) and unsaturated (corn and olive) fat diet than the control cholesterol group. Apo B and apo C-I mRNA levels were not affected by the experimental conditions. Apo A-IV mRNA increased between 66% and 127% in groups in which cholesterol was present. LDL receptor mRNA increased 2 times in the corn fed group compared with the control groups. These results indicate that the expression of genes coding for products involved in lipoprotein metabolism have a differential susceptibility to dietary fat saturation and cholesterol.

Recent migrations from Morocco to Spain.

"This study addressed the problem of the Moroccan immigration into Spain within the context of South-North movements, focusing on analyzing provisional data from the last immigrant regularization in the country completed during the end months of 1991."

Effect of the cryopreservation conditions on the viability of the rumen ciliate Diploplastron (Metadinium) affine.

AIMS: To study the viability of Diploplastron (Metadinium) affine after its cryopreservation at two cooling rates, and the effect of procedure conditions on viability. METHODS AND RESULTS: There were differences in viability between cooling rates (1 and 4 degrees C min(-1)) at 15 or 5 degrees C, but not after thawing. When the equilibrium temperature (25 or 5 degrees C), the cryopreservant (glycerol or dimethyl sulfoxide [DMSO]) and the use of membrane protector were tested, there were no differences caused by the cryopreservant or the membrane protector. However, the equilibrium at 25 degrees C increased the viability (P = 0.005) compared with 5 degrees C. CONCLUSIONS: Viability after thawing was 0.10-0.19. Adding the cryopreservant (either glycerol or DMSO) at 25 degrees C instead of 5 degrees C improves viability of D. affine after thawing. SIGNIFICANCE AND IMPACT OF THE STUDY: Conditions of cryopreservation are largely dependent on the species of rumen protozoa. Number of viable cells after thawing would indicate the possibility of culture recovery for D. affine.

[Influence of the sporulation on glucose-6-phosphate dehydrogenase activity from Aspergillus oryzae (Ahlburg) (author's transl)]. / Influencia de la esporulación sobre la actividad de la glucosa-6-fosfato deshidrogenasa de Aspergillus oryzae (Ahlburg).

Both the specific and the total activity of glucose-6-phosphate dehydrogenase (E.C. 1.1.1.49) of mycelium of Aspergillus oryzae decline progressively from day 6th of incubation, when the period of sporulation begins. Total cellular protein decreases parallely. Cicloheximide stops protein synthesis but not the inactivation of glucose-6-phosphate dehydrogenase. Inhibitors of proteolytic enzymes do not prevent the loss of enzyme activity when added to the cultures. Experiments show no inhibitors of the enzyme to be present in late-stage cells. The enzyme is not excreted into the culture medium.

A cryopreservation procedure for the rumen protozoon Entodinium caudatum: estimation of its viability by fluorescence microscopy.

AIMS: To study the viability of a culture of the rumen protozoon Entodinium caudatum after a cryopreservation procedure by a fluorescence microscopy staining method. METHODS AND RESULTS: Fluorescence method is based on the different colour of cells depending on their membrane integrity. When the temperature effect was studied either by fluorescence or motility, the techniques were correlated (r = 0.727) and their slopes and intercepts were not different (P > 0.05). However, motility showed a higher variation coefficient (0.40 vs 0.12). There were no differences between cooling rates at cryopreservation (1 and 4 degrees C min-1) at 38, 15 or 5 degrees C, nor after thawing. CONCLUSIONS: Fluorescence staining is more accurate than motility for assessing protozoal viability. Viability after thawing was 0.50, and the number of viable cells per 250 microl straw was 320 and 420 for 1 and 4 degrees C min-1. SIGNIFICANCE AND IMPACT OF THE STUDY: This cryopreservation procedure seems to ensure culture recovery for E. caudatum.

Large scale extraction of alpha-lactalbumin and beta-lactoglobulin from bovine whey by precipitation with polyethylene glycol and partitioning in aqueous two-phase systems.

The milk proteins alpha-lactalbumin and beta-lactoglobulin have been isolated from bovine whey by fractional precipitation with polyethylene glycol (PEG) and hydrophobic partitioning in aqueous PEG-hydroxypropylstarch two-phase systems using PEG-bound palmitate as hydrophobic ligand. The possible use of this combination for large scale purification of these whey proteins is discussed.

[6-phosphogluconate dehydrogenase of Aspergillus oryzae (Ahlburg). II. Separation and study of isoenzymes]. / 6-fosfogluconato deshidrogenasa de Aspergillus. II. Separación y estudio de isoenzimas.

Through ammonium sulphate fractionation followed by ion-exchange chromatography, two forms of 6-phosphogluconate dehydrogenase (6j-phosphogluconate: NADP+ oxidoreductase E.C. 1.1.1.44) were isolated from mycelium of Aspergillus oryzae. The Km values for 6PG were the same, but the Km for NADP+ was smaller for isoenzyme I. The Vmx values were also different, with greater activity for isoenzyme II. The optimum pH for isoenzyme I was 7.5. whereas the isoenzyme II had two maximum peaks, at pH 7.5 and 9. Isoenzyme II was the more resistant to thermal inactivation. Inhibition by NADPH was competitive with respect to NADP+, with a Ki value similar for both isoenzymes. The GSSG inhibits isoenzyme I and activates isoenzyme II. The apparent molecular weights determined by gel filtration were 79,000 +/- 2,000 daltons for isoenzyme I and 112,000 +/- 2,000 daltons for isoenzyme II.

Excretion of endogenous and exogenous purine derivatives in sheep: effect of increased concentrate intake.

The present study examined the endogenous urinary excretion of purine derivatives (PD; allantoin, uric acid and xanthine plus hypoxanthine) in fed animals. Four Rasa Aragonesa ewes fitted with simple cannulas in the rumen and proximal duodenum were used. Animals were given a lucerne (Medicago sativa) hay diet, as sole feed (A) or supplemented, respectively, with 220 (B), 400 (C), and 550 (D) g rolled barley grain/d following a 4 x 4 random factorial design. Duodenal flow of purine bases (PB) was determined by the dual-phase marker system. 15N was infused continuously into the rumen to label exogenous or microbial PB. Duodenal PB flow and urinary excretion of PD increased with digestible organic matter intake showing a constant recovery of duodenal PB. The isotope dilution of PD in urine samples confirmed the presence of an endogenous fraction, originating from tissues, that increased from 115.2 (SE 5.84) mumol/kg W0.75 for the basal diet to 304.2 (SE 7.6) mumol/kg W0.75 at the highest level of duodenal PB.

An aqueous hydroxypropylstarch-poly(ethylene glycol) two-phase system for extraction of alpha-lactalbumin and beta-lactoglobulin from bovine whey.

The partitioning of alpha-lactalbumin and beta-lactoglobulin from bovine whey has been studied in an aqueous poly(ethylene glycol) (PEG)-hydroxypropylstarch two-phase system. The influence of several parameters including concentrations of polymers, sodium phosphate buffer, KSCN, and of PEG palmitate, with and without the presence of Ca2+, on the partitioning of the proteins has been investigated. The separation of the two proteins was demonstrated by counter-current distribution. A purification procedure for both proteins has been developed by using PEG-hydroxypropylstarch two-phase system. This system is compared with the more costly standard system based on PEG and dextran. The possible use of the aqueous two-phase systems for batch extraction for large scale purification of these whey proteins is discussed.

Phase partitioning of beta-bungarotoxin-treated cerebrocortical synaptosomes: quantitation of the toxin-vulnerable population.

beta-Bungarotoxin induces changes in the partition of cerebrocortical synaptosomes in Dextran-poly(ethylene glycol) two-phase systems. The toxin action promotes an increase of the partition percentage of synaptosomes in the upper poly(ethylene glycol) rich phase. This effect was observed in both Dextran T500 and Dextran T40 two-phase systems. In both cases an increase of partition in this upper phase of a discrete amount of the whole synaptosomal population accounts for almost 100% of choline acetyltransferase activity, a marker of cholinergic synaptosomes, appearing in this same phase. This effect is specifically dependent on the toxin action since a control experiment shows that extraction into the upper phase of the synaptosomal preparation carried out by addition of an unspecific ligand (hexaethonium) bound to poly(ethylene glycol), could induce the partition of both the whole choline acetyltransferase activity and synaptosomal material in this upper phase. These results suggest that beta-bungarotoxin specifically induces the partition into the upper phase of a toxin-vulnerable synaptosomal population. Therefore, it has been estimated that 30 or 32% of the total synaptosomal preparation is sensitive to the toxin action, as calculated from the maximal increase in the toxin-treated particles partition obtained in the Dextran T500 or Dextran T40 two-phase systems, respectively.