About phoma liliana Chandra & Tandon

Summary In vitro,Phoma liliana could not be distinguished from the later-describedP. ehretiae and two incidental isolates fromMangifera andChrysanthemum. Starting from the principle of the classification in the Deuteromycetes, our conclusion is that we must speak of one and the same form-species, which can be found on different plants.     

The Mg,Ca, EDTA and ATP dependence of Na binding by rat liver microsomes

The role of ionic interactions in the adenosinetriphosphate (ATP) dependent Na binding by rat liver microsomes was investigated. In the concentration range of 0 to 20 mM, Mg and Ca are demonstrated to compete strongly against Na for microsome binding sites. In the presence of Ca, the nonbiological complexing agent ethylenediaminetetraacetate (EDTA) produced a marked increase in Na binding accompanied by a concomitant decrease in Ca binding. Under similar conditions ATP, which is a weaker complexing agent than EDTA, produced quantitatively smaller but qualitatively similar changes in binding. The data show that the effect of ATP on Na binding is not dependent upon the formation of a hypothetical Na binding intermediate in the hydrolysis of ATP as other investigators have postulated. Rather, the effect of ATP is demonstrated to depend upon the presence of unhydrolyzed ATP and its ability to complex divalent cations, and thereby to reduce divalent cation competition against monovalent cations for membrane binding sites.     

CHLOROPLAST DEVELOPMENT IN OCHROMONAS DANICA

When dark-grown cells of Ochromonas danica are placed in the light, the amount of chlorophyll a per cell increases 82-fold; the content of carotenoid pigment, 24-fold. Concomitantly with this increase in chlorophyll and carotenoid pigment, the small proplastid of dark-grown cells develops into a large lamellate chloroplast. During the first 12 hours in the light, vesicles appear within the loose clusters of dense chloroplast granules, enlarge, align themselves into rows (plates in three dimensions), and fuse into discs. Double discs may form from the more or less simultaneous fusion of two adjacent plates of vesicles or by the addition of vesicles to an already formed single disc. Three-disc bands arise by the addition of a disc to an already formed two-disc band through the approach and fusion of more vesicles. After 24 hours in the light, most of the chloroplast bands contain three discs, but the chloroplasts are still small. After 48 hours in the light, almost all the cells contain full-sized chloroplasts with a full complement of three-disc bands. However, at this time the amount of chlorophyll a and carotenoid pigment is only one-half of maximum. During the next 3 days in the light, as the number of chlorophyll and carotenoid molecules per chloroplast approximately doubles, there is a compression of the discs in each band (from 180 to 130 A) and a precise alignment of their membranes. Changes also occur in the nucleus when dark-grown cells are placed in the light. There is an increase in the number of small nucleolar bodies, many of which lie directly against the nuclear envelope, and in a few cells a dense mass of granules is seen between the two membranes of the nuclear envelope.     

An electron microscopic study of the cerebral blood vessels of the opossum

Summary Blood vessels of the opossum brain are paired, artery and vein, and end in a closed loop. Both anatomically and physiologically they are true end-arteries. The two limbs are enclosed within a single basement membrane and are separated from each other by an intercapillary cell thought to be analogous to the usual capillary pericytes. The similarity of this vascular arrangement to that in the rabbit placenta and in the medulla of the kidney is discussed in relation to the counter-current multiplier system.This work was supported in part by the Beaumont-May Institute of Neurology and by a grant, B-425, from the United States Public Health Service.Research Fellow of the National Multiple Sclerosis Society.     

FINE STRUCTURE OF THE NEUROHYPOPHYSIS OF THE OPOSSUM (DIDELPHIS VIRGINIANA)

The neurohypophysis of the opossum (Didelphis virginiana) was studied by electron microscopy in order to amplify Bodian''s classic light microscopic observations in which he demonstrated a definite lobular pattern. The lobule of the opossum neurohypophysis is divided into three regions: a hilar, a palisade, and a septal zone. The hilar portion contains bundles of nerve fibers, the extensions of the hypothalamo-hypophyseal tract containing neurofilaments but few neurosecretory granules. In the opossum, pituicytes have a densely fibrillar cytoplasm. Herring bodies are prominent in the hilar region. They are large bodies packed with neurosecretory granules that have been described as end bulb formations of axons. From the hilar region, axons fan out into a palisade zone where the nerve terminals packed with neurosecretory granules, mitochondria, and microvesicles abut upon basement membranes. The neurosecretory granules are similar to those present in the neurohypophysis of other mammals, except for an occasional huge granule of distinctive type. Material morphologically and histochemically resembling glycogen occurs as scattered particles and as aggregates within nerve fibers. The septal zone, containing collagen, fibroblasts, and numerous small capillaries, is separated from the adjacent glandular tissue by a basement membrane.     

Survey for mitochondrial-desmosome complexes in differentiating epithelia

Summary Mitochondria are frequently found to be closely associated with the plaques of desmosomes in a variety of columnar or cuboidal epithelia of fetal or early postnatal mammals (mouse, rat, human being). The organs in which mitochondrial-desmosome complexes were found include stomach, small intestine, pancreas, kidney, epididymis, seminal vesicle, coagulating gland, thyroid gland. The association has not been observed in simple squamous epithelium (vascular endothelium). Mitochondria lie quite close to desmosomes in the stratum spinosum of stratified squamous mucous epithelium of fetal animals and also to axo-dendritic synapses in still poorly differentiated central nervous system. Mitochondria have also been detected close to attachment sites in ectoderm of the early frog gastrulae. Here there is as yet no visible plaque material.We suggest that the mitochondria may provide energy or some chemical for the formation of the plaque. This hypothesis does not explain why the complexes are not found in poorly differentiated epithelia from older animals.Dedicated to Professor Berta V. Scharrer on her 60th birthday, with affection and admiration. — This study was supported by U.S.P.H.S. research grants NB-05219 and GM-10757 from the National Institutes of Health.     

Titration and Neutralization of Poliovirus in Micro Tissue Culture Under Increased Carbon Dioxide

Modification of the micro tissue culture technique, including incubation under increased CO(2), resulted in prolongation of the viability of the cells. As a consequence, satisfactory titrations of poliovirus and of poliovirus antiserum have been achieved by the micro method. The technique offers a number of advantages over conventional methods.     

High-frequency1H NMR studies of the effects of growth factors and phorbol esters on normal syrian hamster diploid fibroblast cells

The nuclear magnetic resonance (NMR) parameters, spin-lattice (T₁), and spin-spin (T₂) relaxation time, are usually longer for neoplastic cells than for normal cells of the same cell type. This has generally been true at low NMR frequencies (≤100 MHz) when comparisons have been made between normal and neoplastic cells that have both spent a short time in culture. We have previously demonstrated that although the T₁ values of paired normal and neoplastic Syrian hamster (SH) fibroblastic cells in culture are not significantly different when measured at 300 MHz, the 300 MHz T₂ values for the neoplastic cells are smaller than those of the normal cells. (Xin et al. (1986),Cell Biophysics 8, 213.) Since treatment of normal diploid cells with polypeptide growth factors or tumor promoters frequently results in reversible expression of neoplasia-associated phenotypes, T₁ and T₂ were obtained at 300 MHz for treated and untreated SH cells to see if these compounds could also produce smaller 300 MHz T₂ values. Secondary culture SH fetal fibroblast cells were treated with epidermal growth factor (EGF), fibroblast growth factor (FGF), phorbol-12,13-didecanoate (PDD) and 4-α-phorbol-12,13-didecanoate (4αPDD). Treatment with either growth factor resulted in smaller T₂ values, but a statistically significant decrease was not observed for PDD or 4αPDD. The observed reductions in T₂ values were correlated with the morphological and growth-stimulatory effects of these compounds on the cells.     

Beneficial arthropod behavior mediated by airborne semiochemicals. VIII. Learning of host-related odors induced by a brief contact experience with host by-products inCotesia marginiventris (Cresson), a generalist larval parasitoid

Females of Cotesia marginiventris(Cresson), a generalist larval parasitoid, were observed to respond to host related odors in a four-arm olfactometer. The females were significantly more responsive to the odors after a brief contact experience with host-damaged leaves contaminated with host by products. During the experience, actual encounters with hosts were not required to improve subsequent responses to host-related odors. The response to odors of the plant-host complex with which parasitoids had experience was significantly higher than the response to odors of an alternative plant-host complex. This suggests that the experience effect is due, at least partly, to associative learning. We suspect that females of this generalist parasitoid, as was recently found for those of a specialist, recognize specific semiochemicals when they contact frass of suitable host larvae. The parasitoids, subsequently, associate the surrounding odors with the possible presence of hosts, and use these odors as cues in their search for more hosts. This could be an important component in the host-searching behavior of many parasitoids.Mention of a proprietary product does not constitute an endorsement or the recommendation for its use by the USDA.