Petrology and paleogeographic significance of Tertiary nannoplankton-foraminiferal limeston,Guam

The tertiary stratigraphic column on the island of Guam, in the Mariana Island Arc of the western Pacific, is composed largely of volcanic rocks and limestones of shallow-water reef and bank facies. Small amounts of fine-grained limestones, of Eocene, Oligocene and Miocene age, occur interbedded with the volcanic rocks and reef limestones, and consist chiefly of planktonic foraminiferal tests embedded in a matrix of calcareous nannofossils. Although compositionally these pelagic carbonates are nearly identical to nannoplankton-foraminiferal oozes of the deep-sea floor, their deposition probably occurred at comparatively shallow depths — from a few hundred to perhaps 1000–2000 meters rather than several kilometers. The most favorable paleogeographic settings for pelagic deposition of this kind were probably intra-arc basins and shelf areas within the paleo-Mariana Island Arc during periods of volcanic inactivity. The spatial association of these pelagic limestones with shallow-water reef complexes, or with beds of redeposited, reef-derived coarse skeletal material, may serve to differentiate them from their deep-sea counterparts.     

Aspects of the dimorphism of Histoplasma farciminosum: a light and electron microscopic study.

Within 48h following the induction of mycelial to yeast-like phase conversion of Histoplasma farcininosum, randomly occurring hyphal cells were observed to contain multiple nuclei and markedly increased numbers of mitochondria. Yeast-like cells arose as buds from swollen tips of terminal hyphae, as sessile buds along the hyphae, and as buds from chlamydospores. Yeast-like cells were characterized by the presence of numerous buds over the surface of the mother cell. Bud scars were evident in the cell wall of the mother cell following abscission of the bud cell. Little similarity was noted between the fine structure of yeast-like H. farciminosum and that reported for H. capsulatum. The yeast-like cells of H. frciminosum underwent rapid transformation to the mycelial phase at 25 degrees C. The hyphal cell wall originated from the inner layer of cell wall of the yeast-like form. The cytoplasm of the hyphal cell usually contained a single nucleus, scattered mitochondria and occasional lipid storage bodies. Occasionally, Woronin bodies were observed at the septal pore.     

Observations of a naturally-occurring lattice array of ribosomes in ultrathin section of ajellomyces dermatitidis

A highly organized crystalline lattice array believed to represent an intact naturally-occurring polyrisobome was observed in ultrathin section of a hyphal cell ofAjellomyces dermatitidis. This remarkable structure was composed of approximately 120 ribosomal particles in a high degree of 3-dimensional order. Connecting fibers thought to be informational ribonucleic acid were clearly demonstrated between the adjacent ribosomal particles of the lattice array. Subsequent attempts to induce ordered arrays of ribosomes in the hyphae ofA. dermatitidis by pre-cooling and treatment with physiological concentrations of vinblastine sulfate were not successful. It was concluded that the demonstration of naturally-occurring polyribosomes in this fungal organism by conventional techniques of electron microscopy was entirely fortuitous, and that such observation in ultrathin sections is an exceedingly rare event. Further, we believe this report to be the first demonstration by electron microscopy of an intact naturally-occurring polyribosome from fungal tissue.     

Thymus cell maturation: II. Differentiation of three “mature” subclasses in Vivo

Several thymus cell subclasses may be defined on the basis of their sedimentation velocity, their light-scattering properties (a measure of cell volume), or binding of a fluoresceinated anti-Thy 1.2 antiserum. Using a multiparameter fluorescence-activated cell sorter (FACS), cells with distinguishable light-scattering or fluorescence intensity (after staining with fluorescein anti-Thy 1.2) were separable for analysis of intrathymic maturation pathways. Outer thymic cortical large and medium lymphocytes were the only cells labeled within 1 hr after transcapsular diffusion of administered [³H]thymidine. These labeled cells were also entirely contained in the brightest fluorescence intensity (with fluorescein anti-Thy 1.2) subclass. Under conditions of [¹H] thymidine “chase” in vivo, label shifted proportionately and apparently in parallel to three “mature” subclasses: (1) small thymocytes with high surface concentrations of Thy 1.2, representing ~ 80% of all thymus cells; (2) slightly larger cells, with very low surface Thy 1.2, which are indistinguishable from cortisone-resistant thymocytes, and which make up less than 10% of all thymus cells; (3) dead or fragile cells.     

Characterization of subpopulations of T lymphocytes: I. Separation and functional studies of peripheral T-cells binding different amounts of fluorescent anti-Thy 1.2 (theta) antibody using a fluorescence-activated cell sorter (FACS)

Peripheral T lymphocytes in mice can be distinguished by the presence of the Thy 1.2 (theta) cell surface antigen. The fluorescence-activated cell sorter (FACS) was used to analyze and separate T-cells from peripheral lymphoid cell suspensions after incubation with fluorescein-labeled anti-Thy 1.2 (F anti-Thy 1.2). Stained cells were markedly reduced in nu/nu mice, in mice carrying the Thy 1.1 allele (theta-AKR), and were not seen after incubation with anti-Thy 1.2 that had been absorbed with CBA brain. According to these criteria, the stained cells were termed “T lymphocytes.”Among the T lymphocytes, there was considerable heterogeneity of fluorescent staining. The FACS was used to separate T-cells from other cells and further to separate T-cells with high intensity F anti-Thy 1.2 fluorescence (bright T-cells) from those with less F anti-Thy 1.2 fluorescence (dull T-cells). Separated bright T and dull T lymphocytes were shown to have several different functional properties. Dull T-cells appeared more sensitive to small doses of ALS in vivo, homed to lymph node in higher proportions than did bright T-cells, and were not affected by the short-term effects of thymectomy in adult life. Bright T lymphocytes, by contrast, were resistant to the in vivo effects of ALS, homed preferentially to spleen rather than lymph node in irradiated hosts, and were reduced shortly after adult thymectomy. Separated populations of bright and dull T-cells showed reduced ability to produce cytotoxic activity after in vitro sensitization, while mixtures of these two subpopulations of T-cells produced synergistic cytototoxic responses. The ontogenic and functional implications of these findings are discussed.     

Synthesis and secretion of lipoprotein lipase in 3T3-L1 adipocytes. Demonstration of inactive forms of lipase in cells

3T3-L1 adipocytes in culture incorporated [35S]methionine into a protein which could be immunoprecipitated with chicken antiserum to bovine lipoprotein lipase. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed this protein had an Mr of 55,000, similar to that of bovine lipoprotein lipase, and accounted for 0.1-0.5% of total protein synthesis in the adipocytes. Lipoprotein lipase protein was present in small amounts in confluent 3T3-L1 fibroblasts, and the amount increased many-fold as the cells differentiated into adipocytes. This increase was accompanied by parallel increases in cellular lipase activity and secretion. When cells were grown with [35S]methionine, the amount of label incorporated into lipoprotein lipase increased for 2 h and then leveled off. Pulse-chase experiments showed that half-life of newly synthesized lipase was about 1 h. Turnover of lipoprotein lipase in control cells involved both release to the medium and intracellular degradation. When N-linked glycosylation was blocked by tunicamycin, the cells synthesized a form of lipase that had a smaller Mr (48,000), was catalytically inactive, and was not released to the medium. Radioimmunoassay demonstrated that 3T3-L1 adipocytes contained an unexpectedly large amount of lipoprotein lipase protein. 55% of the enzyme protein in acetone/ether powder of the cells was insoluble in 50 mM NH3/NH4Cl at pH 8.1, a solution commonly used to extract lipoprotein lipase; 27% of the lipase protein was soluble but did not bind to heparin-Sepharose and had very low lipase activity; and the remaining 13% was soluble, bound to heparin-Sepharose, and had high lipolytic activity. About one-half of the lipase released spontaneously to the medium was inactive, and lipase inactivation proceeded in the medium with little loss of enzyme protein. Lipoprotein lipase released heparin, in contrast, was fully active and more stable. When protein synthesis was blocked by cycloheximide, the level of lipoprotein lipase activity in adipocytes decreased more rapidly than the amount of lipase protein in the cells. Most of the inactive lipoprotein lipase in adipocytes probably results from dissociation of active dimeric lipase, but some could be a precursor of active enzyme.     

Evidence for the activation of the multifunctional Ca2+/calmodulin-dependent protein kinase in response to hormones that increase intracellular Ca2+

The phosphorylation state of six cytoplasmic proteins is increased following treatment of isolated rat hepatocytes with hormones that elevate free intracellular Ca2+ levels (Garrison, J. C. and Wagner, J. D. (1982) J. Biol. Chem. 257, 13135-13143). Tryptic 32P-phosphopeptide maps of two of the substrates, pyruvate kinase and a 49,000-dalton protein, the major 32P-labeled protein in hepatocytes, were prepared following stimulation of cells with vasopressin, a Ca2+-linked hormone. Peptide maps of the 49,000-dalton protein phosphorylated in vitro with the recently identified multifunctional Ca2+/calmodulin-dependent protein kinase contained phosphopeptides identical to those observed in the intact cell, suggesting that this kinase is activated in response to Ca2+-mobilizing hormones. Similar in vitro phosphorylation experiments with pyruvate kinase suggested that the Ca2+/calmodulin-dependent protein kinase can phosphorylate not only the serine residues observed following vasopressin stimulation of the intact cell but also additional threonine residues. Both pyruvate kinase and the 49,000-dalton protein are also phosphorylated in the hepatocyte in response to glucagon and in vitro by the cAMP-dependent protein kinase. Both vasopressin and glucagon appear to stimulate the phosphorylation of identical serine residues in pyruvate kinase but only vasopressin enhances the phosphorylation of certain sites in the 49,000-dalton protein. Comparison of the tryptic phosphopeptide maps of these substrates phosphorylated in vitro with either the Ca2+/calmodulin-dependent protein kinase or the cAMP-dependent protein kinase suggests that the Ca2+-dependent kinase can phosphorylate unique sites in both substrates. It appears to share specificity at other sites with the cAMP-dependent protein kinase. Overall, the results suggest that the multifunctional Ca2+/calmodulin-dependent protein kinase plays an important role in the response of the hepatocyte to a Ca2+ signal.     

Amphotericin B-induced changes in K+ content, viability, and ultrastructure of yeast-phase Histoplasma capsulatum.

Yeast-phase cells of Histoplasma capsulatum were challenged with amphotericin B, and membrane perturbation was monitored by K+ efflux. Suspensions of washed cells readily absorbed about 1.12 microgram of amphotericin B per mg (dry weight) and further nonspecific sites were also apparent. The dose-response curve for initial rate of K+ efflux was sigmoidal within the range 0.1 to 1.0 microgram of amphotericin B per ml. A fungistatic concentration of amphotericin B (0.3 microgram/ml) evoked an efflux of 85 to 90% K+ from the cells within 15 min, but cell viability decreased only 13% (yeast phase) or 33% (transformed to mycelial units). Ultrastructural changes in treated cells were detected within 5 min, and the hallmark was expansion of vacuoles during the 1-h monitoring period. In contradistinction to a previous report, the appearance of the protoplasmic membrane was not altered by fungistatic concentration. When treated cells were returned to a fresh growth medium, there was a pronounced lag (20 h). During this apparent recovery phase, the large vacuoles fragmented and returned to normal size. It is proposed that vacuoles of H. capsulatum act as a spatial buffer of considerable survival value to stressed cells.     

Yeastlike to mycelial phase transformation of Histoplasma capsulatum as observed by scanning electron microscopy

Details of the sequential events occurring during the critical phases of yeast to mold morphogenesis of the dimorphic fungal pathogenHistoplasma capsulatum as seen by the new technique of scanning electron microscopy are described and illustrated by electron micrographs.No conspicuous surface sculpturing was observed for the normal yeastlike cell immediately before or the newly formed hyphal cell after the critical period of transformation. However, both the parent yeastlike cell as well as the intermediate conversional cell shows a furrowing of the external cell surface which is due possibly to changes in internal cell pressure resulting from the migration of cell contents into the newly forming hyphal cell.     

Effects of centrifugal force on functional and structural integrity of rat liver ribosomes

The ability of rat liver ribosomes to support in vitro protein synthesis was not adversely affected, and generally tended to increase as the centrifugal force at which they were isolated increased. Polysomal material tended to decrease while 40S and 60S ribosomal subunits apparently increased at progressively higher centrifugal forces. Ribosomal "purity", revealed by u.v. spectrophotometric analysis, deteriorated as centrifugal force increased. Contamination by material that absorbed at 230 nm was particularly evident.