Trends in economic traits, halothane sensitivity, blood group and enzyme systems of Swiss Landrace and Large White pigs

Pigs deriving from 150 breeding centres constituting a representative section of elite breeding herds (2496 Swiss Landrace pigs, 587 Swiss Large White pigs) were subjected to blood typing during the period 1981 to 1984. Production traits such as daily gain, feed conversion ratio, lean meat content and meat quality score were available to show the trend in these performance traits since 1978. Field data on the halothane reaction of 14 270 Swiss Landrace (SL) pigs were used to assess the porcine stress syndrome during the period 1978-1983. In SL pigs the frequency of the alleles Ha, PhiB and AdaA decreased significantly, and that of the Hc and PhiA increased during the period of the study. The frequency of the Ha allele dropped from 0.36 in 1981 to 0.20 in 1984, whereas the Hc allele rose from 0.22 to 0.37. In Swiss Large White (SLW) pigs, on the other hand, the frequency of the Ha allele increased constantly from 0.31 to 0.37 during this period. An initial frequency of 17.7% (1978) halothane reactors in SL pigs was lowered to 0.7% (1982) after five years of halothane testing. In SL pigs the meat quality scores improved regularly, whereas in SLW pigs it did not change very much. The percentage of PSE animals in the SL breed was reduced from 32.7% in 1978 to 7.1% in 1983. Because the Hal locus is associated with production traits such as meat quality, linkage disequilibria could explain the observed associations between the H and Phi types and production traits.     

Degradation of Dehydrodivanillin by Anaerobic Bacteria from Cow Rumen Fluid

Dehydrodivanillin (DDV; 0.15 g/liter) was biodegradable at 37°C under strictly anaerobic conditions by microflora from cow rumen fluid to the extent of 25% within 2 days in a yeast extract medium. The anaerobes were acclimated on DDV for 2 weeks, leading to DDV-degrading microflora with rates of degradation eight times higher than those initially. Dehydrodivanillic acid and vanillic acid were detected in an ethylacetate extract of a DDV-enriched culture broth by thin-layer, gas, and high-performance liquid chromatographies and by mass spectrometry.     

Limited nonenzymatic glucosylation of low-density lipoprotein does not alter its catabolism in tissue culture

This study examines the effects of various degrees of chemical modification of low-density lipoprotein (LDL) on its catabolism by various cell types. Moderate glucosylation of LDL does not alter its interaction with the high-affinity receptor present on human fibroblasts at concentration of 5-2000 micrograms LDL-cholesterol/ml. Only heavily glucosylated LDL (more than 12 lysine residues glucosylated per apolipoprotein B) or LDL glucosylated in the presence of Na(CN)BH3, i.e., conditions not expected to occur in diabetes, inhibit receptor-mediated internalisation and degradation. Moderately glucosylated LDL is also readily recognized by cultured rat hepatocytes and porcine endothelial cells. Human monocyte-derived macrophages accumulate cholesteryl ester when incubated with acetylated LDL for 12 days but no enhanced cholesteryl ester formation was found when native or glucosylated LDL (3.3 lysines glucosylated per apolipoprotein B) were used.     

A sensitive method to introduce membrane-bound proteins into recipient cells based on affinity enrichment of lipid vesicles to the recipient cell prior to fusion

A sensitive analytical procedure for studying membrane-bound structures has been developed. Membrane glycoproteins inserted into liposomes were transferred to recipient cells by use of a lectin, concanavalin A, bound to the cells as a bridge to generate proximity between the recipient cell and the glycoprotein-containing liposome, prior to exposure to the fusing agent, poly(ethylene glycol). Partially purified histocompatibility antigen from rats was introduced into the membrane of human lymphocytes. After treating the cells with poly(ethylene glycol) under fusion conditions, some of the antigen present in the preparation could not be eluted with alpha-methyl mannoside and EDTA, indicating that incorporation in the cell membrane had taken place. This antigen remained exposed on the lymphocyte surface for approximately 1 h as demonstrated by sensitivity of the lymphocytes to the lytic effect of an antiserum to the histocompatibility antigen in the presence of complement. Some of the lectin molecules seemed to be internalized in the cells but no induction of cell mitosis was observed. The described method gives an opportunity to work with small amounts of membrane proteins inserted into liposomes, introducing them into recipient cells for analysis of their biological activities.     

Effect of sulfhydryl-disulfide state on protein phosphorylation: phosphorylation of bovine serum albumin

Bovine serum albumin (BSA) was phosphorylated by the catalytic subunit of cAMP-dependent protein kinase under general protein phosphorylation conditions. The optimal pH for this phosphorylation was 9.0. The K0.5 (the concentration required for 50% of maximal phosphorylation) for BSA at pH 7.5 was 15 microM. One mole of phosphate was incorporated per mole of BSA, and only one phosphopeptide fragment was obtained after extensive proteolysis with trypsin. BSA phosphorylation required dithiothreitol or GSH, but GSH was only one-fiftieth as effective as dithiothreitol. GSSG counteracted the effect of dithiothreitol and GSH. Phosphorylation increased in a time-dependent and dithiothreitol concentration-dependent manner when BSA was preincubated with dithiothreitol. The increase in the incorporation of 32P correlated with the appearance of up to six free sulfhydryl groups. The effect of dithiothreitol on BSA appeared reversible, since reoxidation of reduced BSA decreased its susceptibility to phosphorylation. These experiments showed that this in vitro phosphorylation is dependent on the sulfhydryl-disulfide state of BSA. The possible implications of the sulfhydryl-disulfide state of proteins in the regulation of phosphorylation are discussed.     

Chloride as allosteric effector of yeast aminopeptidase I

Activation of yeast aminopeptidase I by chloride was studied by kinetic methods. Several effects contributed to overall activity enhancement: At low concentrations of Zn2+ (an essential component of aminopeptidase I) chloride increased the amounts of active enzyme by reducing the cooperativity of metal binding. In addition, substrate turnover was enhanced due to increased kcat and a moderate decrease of Km. At high concentrations of Zn2+ substrate saturation curves were sigmoidal. Under these conditions chloride activated by restoring Michaelis-Menten kinetics of substrate turnover. At the same time, reconstitution of active enzyme from apoprotein and Zn2+ was substantially accelerated and its inactivation due to loss of Zn2+ was retarded. Co2+-Substituted aminopeptidase I, although catalytically active, was much less sensitive to chloride activation. Apparent binding constants for chloride, as estimated from its effects on metal binding and catalysis, respectively, were different. This suggests that two independent activation mechanisms may be operative. Both appear to be mediated by conformational changes of the enzyme protein.     

Changes in the mucosa of the duodenum and stomach as a result of experimental duodenal ulcers and vagotomy

By means of the transmissive and scanning electron microscopy methods and radioautography, structure of mucous membrane of the stomach and duodenum has been studied under experimentally induced duodenal ulcers before and after vagotomy during various time. The vagotomy results in accelerated healing of the ulcer defect. This is connected with an increased proliferative activity in the crypta cells, however, this is accompanied with deceleration of their differentiation. Under the duodenal ulcers the amount of chief and parietal cells increases in the gastric mucous membrane, this depends on gastrostasis produced by stenosis of the pylorus. At vagotomy the amount of the chief and parietal cells in the fundal glands of the mucous membrane decreases; this is accompanied with a lowered secretory activity.     

Retinoic acid modulation of 1,25(OH)2 vitamin D3 receptors and bioresponse in bone cells: species differences between rat and mouse

Retinoic acid (RA) caused a reduction in the level of 1,25(OH)2D3 receptors to 1/3 of control in rat osteoblast-like cells (ROB) while increasing the receptor level to 3-fold the control in mouse osteoblast-like cells (MOB). Scatchard analysis of receptor binding indicated that there was no change in affinity for 1,25(OH)2D3. The changes in receptor levels required time to develop and were dose-dependent. RA also modulated the ability of cells to respond to 1,25(OH)2D3 as measured by the induction of the enzyme 25(OH)D3-24 hydroxylase. Induction of enzyme activity by 1,25(OH)2D3 closely paralleled receptor level established by RA pretreatment. In MOB, the up-regulation of the receptor occurred despite the action of RA to inhibit DNA, RNA and protein synthesis. However, RA stimulation of 1,25(OH)2D3 receptor levels was blocked by the addition of cycloheximide or actinomycin D, indicating that the up-regulation required protein and RNA synthesis. The opposite effect of RA on mouse and rat cells suggests that important species-dependent factors modulate the action of retinoids on mammalian cells.     

Major contribution of epididymis to alpha-glucosidase content of ram seminal plasma

Acid alpha-glucosidase and L-carnitine (a well-known epididymal marker) were measured in rete testis and epididymal fluids of adult male rams. These fluids were collected by selective catheterization or by a micropuncture technique, respectively. Both parameters remained at a low and constant level in rete testis and all along caput and corpus epididymidis. Then they increased at equivalent rates in cauda epididymidis to much higher levels than those in seminal plasma (5 mU/mg protein and 10 mM, respectively). An optimum pH study of alpha-glucosidase activity in these fluids showed two well-separated peaks in rete testis and caput epididymal fluids around pH 4 and 7, respectively, but only a single peak at pH 4 in cauda epididymidis that was comparable to the one in seminal plasma. Sucrose density gradient fractions analyzed for their enzyme content in the absence or presence of sodium dodecyl sulfate (1% w/v), a selective inhibitor of acid alpha-glucosidase activity, allowed the demonstration of two enzyme forms at pH 6.8 in rete testis fluid sedimenting in the 7S and 4S regions of the gradient, while a unique 4S form was encountered in cauda epididymidis and in seminal plasma. Although the fate of the minor 7S component of the rete testis fluid in its epididymal transit is presently unknown, similarities between the enzyme in cauda epididymidis and seminal plasma are strong enough to support the hypothesis that epididymis contributes primarily to the acid alpha-glucosidase content of ram seminal plasma.