Nuclear interactions of retinoic acid-binding protein in chemically induced mammary adenocarcinoma.

Cellular retinoic acid-binding protein (CRABP) was detected in the nuclear fraction of N-methyl-N-nitrosourea-induced mammary cancers after the incubation of cytosol containing [3H]retinoic acid (RA)-bound CRABP with isolated nuclei. CRABP extracted from the nuclei in buffer containing 0.4 M-KCl sedimented as a 2 S component when subjected to sucrose-density-gradient analysis. [3H]RA-CRABP was found to be a prerequisite for the detection of nuclear binding, since the incubation of isolated nuclei or 0.4 M-KCl extract of the nuclei with [3H]RA did not result in any significant binding. Incubation of [3H]RA-CRABP at 25 or 30 degrees C before incubation with the nuclei neither altered the sedimentation coefficient nor enhanced the nuclear binding compared with 0 degrees C incubation. The tumour nuclei contained a saturable number of binding sites with a dissociation constant of 1.6 x 10(-9) M. These results indicate that the action of retinoic acid in the target organ may be mediated by its interaction with the nuclei.     

Sciatin Is a Transferrin-Like Polypeptide

Abstract: Sciatin, an acidic glycoprotein from chicken sciatic nerve, has myotrophic effects on avian skeletal muscle cells in culture. As sciatin was found to have certain structural similarities to transferrin, we further investigated the physicochemical characteristics of sciatin in order to determine the relationship between these two proteins. Sciatin was found to be strikingly similar to ovotransferrin in amino acid composition. In addition, amino acid sequence analysis revealed that sciatin and ovotransferrin had identical amino-terminal sequences for at least the first 20 amino acid residues. Chicken ovotransferrin, but not human serum transferrin, cross-reacted with rabbit antisciatin antibodies upon rocket immunoelectrophoresis and double immunodiffusion in agar. In addition, in the presence of bicarbonate, sciatin bound approximately 2 mol ferrous iron/mol protein. Using the purification procedure developed for sciatin, we purified a protein from chicken serum that cross-reacted with antisciatin serum, migrated at a position identical to that of sciatin or ovotransferrin on two-dimensional gel electrophoresis, had an amino composition very similar to ovotransferrin and sciatin, and had myotrophic effects on cultured muscle cells. From these data, we conclude that sciatin is a growth-promoting polypeptide closely related in structure to transferrin.     

Amino acid transport and interconversions in tissues of freshly caught and food-deprived plaice, Pleuronectes platessa L.

Distribution ratios (intracellular/extracellular concentration) of α-amino isobutyric acid (AIB) and activities of the transaminases of alanine (Ala AT), aspartate (Asp AT), leucine (Leu AT) and glutamate dehydrogenase (GDH) were determined in tissues of freshly caught plaice, Pleuronectes platessa , deprived of food for three months. Liver, red muscle and white muscle demonstrated increased distribution ratios for AIB, while the ratios decreased in kidney and gill with deprivation. Values of the distribution ratio were below 1.0 only in white muscle, with kidney and liver having the highest absolute values. Transaminase activities generally rose with deprivation in all tissues, although the absolute increases were greatest in liver and for the two enzymes Ala AT and GDH. These data indicate that with food deprivation, the role of the liver in amino acid metabolism is maintained and slightly enhanced, while that of the kidney is reduced. Both muscle types (red and white) showed increased water content implicating protein mobilization which could enhance the availability of amino acids for liver gluconeogenesis and metabolite sparing in other tissues during conditions of depletion.     

Progression of Epiphytic Microflora in Wheat and Alfalfa Silages as Observed by Scanning Electron Microscopy

Wheat and alfalfa silages were examined by scanning electron microscopy and standard methods of microbial enumeration. Epiphytic microflora were present at levels of 10⁶ to 10⁸/g in the fresh-cut plants. This flora was initially observed microscopically primarily on the surfaces. After 4 days of fermentation, lactic acid bacteria were observed on the surface in high concentrations near open stomata and throughout the interior mesophyll air sac spaces. At 4 days, populations on interior surfaces were restricted to the exterior surfaces of the air sacs. After 8 days the mesophyllic cells showed marked deterioration, and bacteria were observed on their inner surfaces. At 32 days, the end of the fermentation, vascular bundles and epidermal cells remained intact whereas stomata and mesophyllic cells were collapsed and often contained microorganisms. It is concluded that the interior of the leaves offers substantial nutritional and environmental advantages to epiphytic flora and is an important if not major deterioration site in fermented products. Since little deterioration of exterior surfaces was observed, these sites may play a minor role in supplying nutrients for microbial growth.     

Analysis of structural polypeptides of purified human cytomegalovirus.

Human cytomegalovirus strain C87 was purified by the following procedures. (i) Extracellular virus was concentrated by centrifugation at 100,000 X g for 90 min and passed through a Bio-Rad Bio-Gel A-15m column. Most of the virus was recovered in the void volume. (ii) After two consecutive isopycnic potassium tartrate gradient centrifugations (20 to 50%), coinciding peaks of plaque titer, protein, and radioactivity were found at a density of from 1.20 to 1.21 g/cm3. To characterize the structural polypeptides of human cytomegalovirus and to establish relative purification criteria, virus was purified from two mixtures: (i) [35S]methionine-labeled extracellular virus mixed with an equal volume of unlabeled normal culture fluid; (ii) unlabeled extracellular virus mixed with an equal volume of [357a1methionine-labeled normal culture fluid. The extent of purification, as judged by the ratio of cellular to viral radioactivity, was 39-fold; i.e. about 2.5% of the protein in the purified virus preparation could be accounted for by host protein contamination. Electrophoresis of purified [35S]methionine-labeled virus on a polyacrylamide gel slab showed that there were at least 33 viral structural polypeptides (VPs), and their molecular weights ranged from 11,000 to 290,000. Autoradiograms obtained from electropherograms of purified [14C]glucosamine labeled virus showed six bands. Four of these were so broad that several VPs corresponded to each of the glycosylated bands. When heavy (two fractions close to 1.21 g/cm3) and light (two fractions close to 1.20 g/cm3) fractions of the PFU peak from the second potassium tartrate gradient were analyzed separately, the number of polypeptides observed was the same, but the relative amounts of some polypeptides differed. The major polypeptide, VP17, was found in greater amounts in the heavy fraction (35%) than in the light fraction (22%). The amount of DNA as a percentage of the weight of protein was 2% for the light fraction and 1% for the heavy fraction.     

Kinetics and thermodynamics of lactate dehydrogenases from beef heart, beef muscle, and flounder muscle.

The eight rate constants for a four-step ordered ternary-complex mechanism have been compared for lactate dehydrogenases (EC1.1.1.27) from three sources, beef heart, beef muscle, and flounder muscle. The rate constants were determined at temperatures ranging from 5 degrees C to 50 degrees C, and the corresponding activation parameters deltaG not equal to, deltaH not equal to, and deltaS not equal to were calculated. Significant differences are noted for the values for the three types of enzyme. The relative heights of the activation barriers are much the same in all three cases, differences in kinetic behavior resulting mainly from differences in the stable binary and ternary enzyme-substrate complexes. These complexes are, in general, at lower free-energy and enthalpy levels of the beef-heart and beef-muscle enzymes than for the flounder-muscle enzyme. A high degree of compensation is found between the enthalpies and entropies of activation, resulting in relatively small differences between the free energies (and rates) for homologous steps with different enzymes. Analysis of the results, on the assumption that the compensation effect is due to weak-bonding effects, suggests that there are fewer weak bonds in the stable complexes of the muscle enzymes.     

Effects Ala54Thr polymorphism of FABP2 on obesity index and biochemical variable in response to a aerobic exercise training

The purpose of the current study was to investigate whether or not the FABP2 gene polymorphism modulated obesity indices, hemodynamic factor, blood lipid factor, and insulin resistance markers through 12-week aerobic exercise training in abdominal obesity group of Korean mid-life women. A total of 243 abdominally obese subjects of Korean mid-life women voluntarily participated in aerobic exercise training program for 12 weeks. Polymerase Chain Reaction with Restriction Fragment Length Polymorphism (PCR-RFLP) assay was used to assess the FABP2 genotype of the participants (117 of AA homozygotes, 100 of AT heterozygotes, 26 of TT homozygotes). Prior to the participation of the exercise training program, baseline obesity indices, hemodynamic factor, blood lipid factor, and insulin resistance markers were measured. All the measurements were replicated following the 12-week aerobic exercise training program, and then the following results were found. After 12-week aerobic exercise training program, wild type (Ala54Ala) and mutant type (Ala54Thr+Thr54Thr) significantly decreased weight (P > .001), BMI (P > .001), %bf (P > .001), waist circumference (P > .001), WHR (P > .001), muscle mass (wild type p < .022; mutant type P > .001), RHR (P > .001), viseceral adipose area (wild type p < .005; mutant type P > .001), subcutaneous area (P > .001), insulin (wild type p < .005; mutant type P > .001) and significantly increased VO2max (P > .001). And wild type significantly decresed NEFA (P > .05), glucose (P > .05), OGTT 120min glucose (P > .05) and significantly increased HDLC (p > .005). Mutant type significantly decreased SBP (P > .001), DBP (P > .01), TC (P > .01), LPL (P > .05), LDL (P > .001), HOMA index (P > .01). The result of the present study represents that regular aerobic exercise training may beneficially prevent obesity index, blood pressure, blood lipids and insulin resistance markers independent of FABP Ala54Thr wild type and mutant type.