Bead rings at the endoplasmic reticulum-golgi complex boundary: morphological changes accompanying inihibition of intracellular transport of secretory proteins in arthropod fat body tissue

Golgi complex beads are 10-nm particles arranged in rings on the smooth surface of rough endoplasmic reticulum (ER) makind the forming face of the Golgi complex (GC). In arthropod cells they stain specifically with bismuth. Their morphology has been studied after treatment with reagents known to interfere with GC function. Inhibitors of oxidative phosphorylation (antimycin A, cyanide, and anoxia), but not an inhibitor of glycolysis (iodoacetate), both cause the bead rings to collapse and the GC saccules to round up, and inhibit transition vesicle (TV) formation. Cycloheximide blocks protein synthesis on ribosomes but does not stop TV formation or disrupt bead rings, even after prolonged treatment (6 h) to allow emptying of the rough ER cisternae. Thus the collapse of bead rings is not attributable to inhibition of protein synthesis, and the ring structure of beads does not require continued protein synthesis and secretion for its maintenance. Valinomycin has effects on the GC similar to those of antimycin A, but {"type":"entrez-nucleotide","attrs":{"text":"A23187","term_id":"833253","term_text":"A23187"}}A23187, monensin, and lasalocid do not affect bead ring structure or TV formation. These results are consistent with valinomycin’s secondarily uncoupling mitochondria, which collapses bead rings and prevents TV formation. Thus inhibitors of oxidative phosphorylation do not influence the beads through cation movement. Because mononsin and lasalocid block secretion at the level of the condensing vacuoles, bead rings are not influenced by blocks in secretion distal to them or by the backup of secretory material. These experiments are consistent with inhibitors of oxidative phosphorylation collapsing bead rings by decreasing intracellular ATP. The concomitant block to TV formation and the collapse of bead rings suggests that integrity of the bead rings is essential for the transport of secretory material from the rough ER to the GC.     

The characterization of growth factor activity in human brain

The purification of fibroblast growth factor from bovine brain has been reported (Gospodarowicz, D., Bialecki, H., and Greenberg, G. (1978) J. Biol. Chem. 253, 3736-3743). Westall et al. (Westall, F. C., Lennon, V. A., and Gospodarowicz, D. (1978) Proc. Natl. Acad. Sci. U. S. A. 75, 4675-4678) showed that bovine brain fibroblast growth factor was composed of three fragments derived by limited proteolysis from myelin basic protein. In the present study using similar purification methods, we isolated a fraction enriched in growth factor activity from human brain. The mitogenic activity could not be resolved from myelin basic protein by chromatographic procedures but, upon isoelectric focusing, the mitogen and myelin basic protein were readily dissociated. At least two potent growth factors (pI values 7.2 to 7.4 and 8.1 to 8.6) were identified. Studies of a relatively crude basic extract of human brain suggested that the brain may contain a number of growth factors.     

The value of electrocardiographic R-wave changes in exercise testing: Preexercise versus postexercise measurements

To determine the usefulness of R-wave amplitude changes during exercise testing for the diagnosis of coronary artery disease (CAD) and to understand the discrepancies that have been described in the literature regarding their value, we studied two groups of patients by means of electrocardiographic (EKG) treadmill testing and coronary arteriography. Group I was composed of 149 patients who were studied prospectively. The specificity of R-wave changes measured from preexercise to immediately postexercise (SRV(5)) was 81%, but that of R-wave changes measured from preexercise to peak exercise (URV(5)) was 46%. A group of 156 patients (Group II) evaluated retrospectively showed a high specificity for the SRV(5) (84%) and poor specificity for the URV(5) (39%). The sensitivity of the SRV(5) was 38% in Group I and 42% in Group II. Therefore, if measured during the immediate postexercise period and not at peak exercise, changes in R-wave amplitude may be of value in the diagnosis of coronary artery disease by electrocardiographic exercise testing.     

Cell wall characteristics of Pseudomonas aeruginosa and its carbenicillin-induced L-form.

L-forms of Pseudomonas aeruginosa were induced and cultured on a medium supplemented with carbenicillin. Morphological studies of the passaged variant revealed the presence of a triple-layered cell wall similar to that found in the parent species. Furthermore, the L-form was found to be more susceptible to gentamicin, kanamycin, tetracycline and colistin sulphate. Chemical analysis of the lipopolysaccharide fraction showed a difference in phosphorus content, and changes in cell wall envelope fatty acid content were also exhibited. It is suggested that these differences may influence the transport of certain antibiotics through the cell wall.     

The stimulation by transmitter substances and putative transmitter substances of the net activity of phospholipase A2 of synaptic membranes of cortex of guinea-pig brain.

1. The distribution of the hydrolyses of phosphatidylcholine by phospholipase A2 and phospholipase A1, and the hydrolysis of lysophosphatidylcholine by lysophospholipase, in subcellular and subsynaptosomal fractions of cerebral cortices of guinea-pig brain, was determined. 2. Noradrenaline stimulated hydrolysis by phospholipase A2 in whole synaptosomes, synaptic membranes and fractions containing synaptic vesicles. 3. Stimulation of hydrolysis by phospholipase A2 in synaptic membranes by noradrenaline was enhanced by CaCl2, and by a mixture of ATP and MgCl2. The optimum concentration of CaCl2, in the presence of ATP and MgCl2, for stimulation by 10 muM-noradrenaline was in the range 1-10muM. The optimum concentration for ATP-2MgCl2 in the presence of 1 muM-CaCl2 was in the range 0.1-1mM. 4. Hydrolysis by phospholipase A2 of synaptic membranes was also stimulated by acetylcholine, carbamoylcholine, 5-hydroxytryptamine, dopamine (3,4-dihydroxyphenethylamine), histamine, psi-aminobutyric acid, glutamic acid and aspartic acid. With appropriate concentrations of cofactors, sigmoidal dose-response curves were obtained, half-maximum stimulations being obtained with concentrations of stimulant in the range 0.1-1muM. 5. Taurine also stimulated hydrolysis of phosphatidylcholine by phospholipase A2. There were only slight stimulations with methylamine, ethylenediamine or spermidine. No stimulation was obtained with glucagon.     

Evaluation of late results of surgical treatment of congenital heart disease.

Operative mortality from surgical treatment of congenital heart disease has been steadily reduced over the past 20 years. During the same period it has become clear that a proportion of survivors have residual clinical problems. Some of these are due to imperfect repair, a number being due to factors beyond present surgical control, and some are the consequence of associated cardiovascular defects. The chief problems can be elucidated by an analysis of the results of surgical treatment of six cardiac malformations: simple pulmonary valve stenosis, coarctation of the aorta, secundum atrial septal defect, isolated ventricular septal defect, tetralogy of Fallot and transposition of the great arteries. Recognition of the sequelae of preoperative hemodynamic strain and apparently minor associated malformations is important, and it is possible to anticipate such factors. Long-term follow-up of patients after operation is particularly important.     

Acquisition and maintenance of enterotoxin plasmids in wild-type strains of Escherichia coli

Enterotoxigenic strains of Escherichia coli (ETEC) may produce a heat-labile enterotoxin (LT), a heat-stable enterotoxin (ST) or both enterotoxins. Certain serogroups are represented more frequently than others in ETEC isolated from humans. The transfer of three plasmids encoding enterotoxin production (Ent) to 22 non-toxigenic E. coli strains of many different O:H serotypes was studied. The Ent plasmids encoded ST (TP276), or LT (TP277), or ST + LT (TP214), and all carried antibiotic-resistance determinants. Twenty-one recipient strains acquired TP214, 18 acquired TP277 and 14 acquired TP276. Strains of those serotypes to which ETEC in diarrhoeal studies commonly belong neither acquired nor maintained Ent plasmids with a higher frequency than strains of those serotypes to which ETEC rarely belong. The recipient strains, with one exception, all expressed ST, or LT, or ST and LT, when they had acquired the appropriate plasmid; a non-motile strain belonging to O serogroup 88 expressed LT but failed to express ST when it acquired TP214 or TP277.     

Alleviation of Both Water and Nutrient Limitations is Necessary to Accelerate Ecological Restoration of Waste Rock Tips

Hard rock quarries are commonly located close to national parks and special areas of conservation and are generally regarded as visually intrusive. Consequently, restoration strategies that effectively accelerate natural plant regeneration processes are required. Slate waste tips present extreme conditions for plant establishment with multiple potential limiting factors (e.g., lack of organic matter, nutrients, and poor water retention). In this study, we investigated ecological strategies to accelerate natural regeneration at the largest slate quarry in Europe. A field experiment was conducted to assess ecosystem restoration using a contrasting set of native woody species. Treatments included amendments of waste tips with: polyacrylamide gel to increase water‐holding capacity; mineral fertilizer to increase nutrient supply; and two treatments that increased both (organic waste or boulder clay addition). Ecosystem recovery was evaluated through above‐ and below‐ground productivity (plant and microbial, respectively) and soil analyses. Neither increasing nutrient supply (with mineral fertilizer) nor water‐holding capacity (with polyacrylamide gel) was sufficient, alone, to improve plant establishment. However, both boulder clay and organic waste amendment significantly enhanced plant growth. There was a marked positive interaction in the effects on tree growth of the amendment with organic waste and boulder clay. Large interactions occurred between tree species and substrate amendments. The growth of N₂‐fixing species was strongly favored over non‐fixers where there was no addition of material increasing soil nitrogen supply, whereas the growth advantage of pioneer species over non‐pioneers was greatest with fertilizer, organic waste, or clay additions. Organic waste addition had the greatest positive impact on soil processes.     

甘肃省被子植物分布新记录

报道了甘肃省分布的玄参科(Scrophulariaceae)水茫草属(Limosella Linn.)1个新记录属,以及玄参科(Scrophulariaceae)、木兰科(Magnoliaceae)、蓼科(Polygonaceae)、胡颓子科(Elaeagnaceae)、百合科(Liliaceae)5个新记录种——水茫草(Limosella aquatica Linn.)、峨眉含笑(Michelia wilsonii Finet et Gagnep.)、叉分蓼(Polygonum divaricatum L.)、棱果沙棘(Hippophae goniocarpa Y.S.Lian et al.ex SwensonBartish)、青海黄精(Polygontum qinghaiense Z.L.Wu et Y.C.Yang)。其中,峨眉含笑是国家二级重点保护野生植物。