Biologic-response-modifier-induced indoleamine 2,3-dioxygenase activity in human peripheral blood mononuclear cell cultures

Degradation of tryptophan to kynurenine, catalyzed by indoleamine 2,3-dioxygenase (IDO), has been augmented in human epithelial cell lines treated with human interferon-gamma (HuIFN-gamma). Several human biologic response modifiers, including HuIFN-gamma, HuIFN-beta, HuIFN-alpha, interleukin 2 (HuIL-2), and tumor necrosis factor alpha, have now been assessed for their ability to enhance tryptophan degradation in human peripheral blood mononuclear cell (PMC) cultures. PMC were isolated from normal donors, cultivated in RPMI 1640 medium containing [3H]tryptophan, and treated with individual biologic response modifiers. At various intervals, culture supernatants were removed, fractionated by reversed-phase high performance liquid chromatography, and radioactivity in resultant fractions was determined. Significantly increased amounts of tryptophan catabolites were observed after treatment with HuIFN-gamma, HuIFN-beta, HuIFN-alpha, and HuIL-2, but not human tumor necrosis factor alpha. Often, greater than 30% of available tryptophan was degraded by treated PMC cultures. Although antibodies to HuIFN-alpha, HuIFN-beta, and HuIFN-gamma specifically neutralized the induction of IDO activity in PMC by their respective HuIFN, only anti-HuIFN-gamma antibody also neutralized HuIL-2-induced IDO activity. Furthermore, T24 bladder carcinoma cells, in which IDO was induced by HuIFN-gamma but not by the other biologic response modifiers, were induced to degrade tryptophan by supernatants of HuIL-2-stimulated PMC cultures, but not by HuIFN-beta-stimulated PMC culture supernatants. Thus, whereas HuIL-2 indirectly induced IDO in PMC cultures by stimulating production of HuIFN-gamma, all cases of interferons appeared to induce IDO directly in PMC cultures.     

Arguing from potential

Buckle's article is one of three discussing the potentiality of the human embryo in this issue of Bioethics devoted to the subject of embryo research. (See also Michael Lockwood's "Warnock v. Powell (and Harradine): when does potentiality count?" and Richard M. Hare's "When does potentiality count? A comment on Lockwood.") In his essay, Buckle analyzes some of the distinct ways of arguing about potential, and the different senses of potential on which these arguments rely. He also examines some of the criticisms of the argument from the potential and replies to them, and shows why the argument's protagonists and critics are often at cross-purposes.     

Histochemical localization of IGF-I and IGF-II mRNA in the rat between birth and adulthood

We describe the postnatal ontogeny and localization of insulin-like growth factors I and II (IGF-I and -II) in the rat. We have used oligodeoxyribonucleotide probes for in situ hybridization (hybridization histochemistry) and for Northern blotting. IGF-II mRNA is strongly expressed in liver, skeletal muscle, perichondrium, leptomeninges and choroid plexus of the newborn. Demonstrable levels fall dramatically in the liver at 18-20 days postnatally but persist for longer periods in muscle and remain undiminished throughout life in the pia/choroid plexus, indicating that different control mechanisms operate in these tissues. IGF-I mRNA is predominantly found in the liver. Its level in this organ rises well before levels of IGF-II fall. This suggests that distinct factors govern the expression of IGF-I and -II genes.     

Neighborhood predictors of plant performance

Summary We developed models of inter-individual interference to predict the fecundity of individuals in populations of the annual plant species, Arabidopsis thaliana. An individual plant is modeled as having a neighborhood which is a circular area of fixed radius with the plant at its center. Other plants which share the circle with the focal plant are termed neighbors of the focal plant. We developed an index of neighborhood interference which is the independent variable in a non-linear regression model that predicts individual plant fecundity. We present methods of exploratory data analysis that are useful in determining a best neighborhood radius, defined as that radius which minimizes residual sum of squares, and in deciding on the functional form of the interference index. In developing the interference index for Arabidopsis, we focus on aspects of the spatial distribution of neighbors: their number, distance and angular dispersion.We found that a best (or optimal) neighborhood radius can be resolved, which provides the best predictor of plant performance. Fecundity predictors based on adult neighbors were noticeably better than those based on neighbors at the seedling stage. Rosettes of Arabidopsis may change location during development (they fall over) and the new fallen positions do provide some improvement in the predictor. Taking into account distance to neighbors within the neighborhood provided only negligible improvement in the model. Finally, the incorporation of angular dispersion in the crowding index produced a considerably better fit. The fecundity predictor that included number of neighbors and angular dispersion in the crowding index explained about 70% of the variation in individual seed set.     

The ultrastructure and formation of the calcareous ossicles in the body wall of the sea cucumber Leptosynapta clarki (Echinodermata,Holothuroida)

Summary The calcareous ossicles of the burrowing sea cucumber Leptosynapta clarki have been examined by scanning and transmission electron microscopy. The ossicles occur in the dermis of the body wall and comprise three main types: 1) curved rods; 2) miliary granules; and 3) anchorshaped structures that are paired with oval plates. Rods average about 80 m in length, and miliary granules are typically 20–30 m long. Both of these ossicles appear to form a protective skeleton in regions where the water vascular system and accompanying nerves are located. Anchors and plates are scattered throughout the interambulacra of the body at densities ranging from 2–8/mm². Each anchor measures about 145 m long and is attached to the plate underlying it by a flexible ligament that is composed of collagen fibrils. Tetracycline labeling studies indicate that anchors and plates take several months to reach full size. All developing ossicles appear to be surrounded by a syncytial network of sclerocytes that characteristically possess numerous mitochondria and a conspicuous external lamina. Fully formed anchors lie directly beneath the epidermis and do not protrude through the outermost layer of the body wall. During burrowing, the curved flukes of the anchorshaped ossicles may provide added traction as the buccal tentacles dig through the sediment.List of abbreviations a anchor - ar ambulacral region - cm circular muscle layer of body wall - cs cytoplasmic sheath - d dermis - ep epidermis - f fluke - ild inner layer of dermis - k keel - me myoepithelium - mg miliary granule - n nerve - old outer layer of dermis - os ossicle - pl plate - s sclerocyte - sh shank - st stock     

Organization of the ribosomal ribonucleic acid genes in various wild-type strains and wild-collected strains of Neurospora

Summary The organization of the ribosomal DNA (rDNA) repcat unit in the standard wild-type strain of Neurospora crassa, 74-OR23-1A, and in 30 other wild-type strains and wild-collected strains of N. crassa, N. tetrasperma, N. sitophila, N. intermedia, and N. discreta isolated from nature, was investigated by restriction enzyme digestion of genomic DNA, and probing of the Southern-blotted DNA fragments with specific cloned pieces of the rDNA unit from 74-OR23-1A. The size of the rDNA unit in 74-OR23-1A was shown to be 9.20 kilobase pairs (kb) from blotting data, and the average for all strains was 9.11+0.21 kb; standard error=0.038; coefficient of variation (C.V.)=2.34%. These data indicate that the rDNA repeat unit size has been highly conserved among the Neurospora strains investigated. However, while all strains have a conserved HindIII site near the 5 end of the 25 S rDNA coding sequence, a polymorphism in the number and/or position of HindIII sites in the nontranscribed spacer region was found between strains. The 74-OR23-1A strain has two HindIII sites in the spacer, while others have from 0 to at least 3. This restriction site polymorphism is strain-specific and not species-specific. It was confirmed for some strains by restriction analysis of clones containing most of the rDNA repeat unit. The current restriction map of the 74-OR23-1A rDNA repeat unit is presented.