Changes in Lipid Composition During Manganese-Induced Apoptosis in PC12 Cells.

Lipid composition of membranes is fundamental to modulate signaling pathways relying on lipid metabolites and/or membrane proteins, thus resulting in the regulation of important cell processes such as apoptosis. In this case, membrane remodeling is an early event important for the activation of signaling leading to cell death and removal of apoptotic cells. In the present study, we analyzed phospholipid, cholesterol and fatty acid content during apoptosis induced by manganese in PC12 cells. Lipid analysis of whole cells and detergent-resistant membranes was carried out by HPLC/GC. Results showed that apoptosis is associated with changes in lipid composition detectable in whole cell extracts, namely cholesterol, phosphatidylserine and phosphatidylethanolamine decreases. Noteworthy, phosphatidylserine level reduction was detectable before to the detection of apoptosis, in correlation with our previous study carried out by radioactive labelling. By contrast, phosphatidylserine and phosphatidylethanolamine changes were not detected in detergent resistant membranes, which instead showed an altered composition in phosphatidylinositol, phosphatidylcholine and sphingomyelin in apoptotic cells.

Evidence of DMSO-Induced Protein Aggregation in Cells.

We report on a study of protein aggregation induced on different cell samples by dimethyl sulfoxide (DMSO) addition. DMSO is the most commonly used cryoprotectant because it is supposed to readily diffuse across lipid bilayers, thus reducing water activity within cells; despite its large use, the mechanism of penetration and even the main interaction features with cell components are far from being understood. In the present work, infrared absorption spectroscopy is successfully applied to real time detection of chemical and structural changes occurring in cells during dehydration from water and water/DMSO suspensions. As a most interesting result, DMSO is observed to favor protein aggregation both in cellular model systems, as cultured lymphocytes and fibroblasts, and in human samples for clinic use, as hematopoietic stem cells from cord blood. This effect is evidenced at low water content, analogously to what is observed for protein solutions. Such tendency is not specific of the type of protein and suggests one possible origin of DMSO toxicity.

Lipotoxic stress alters the membrane lipid profile of extracellular vesicles released by Huh-7 hepatocarcinoma cells.

Extracellular vesicles (EVs) are well-known mediators in intercellular communication playing pivotal roles in promoting liver inflammation and fibrosis, events associated to hepatic lipotoxicity caused by saturated free fatty acid overloading. However, despite the importance of lipids in EV membrane architecture which, in turn, affects EV biophysical and biological properties, little is known about the lipid asset of EVs released under these conditions. Here, we analyzed phospholipid profile alterations of EVs released by hepatocarcinoma Huh-7 cells under increased membrane lipid saturation induced by supplementation with saturated fatty acid palmitate or Δ9 desaturase inhibition, using oleate, a nontoxic monounsaturated fatty acid, as control. As an increase of membrane lipid saturation induces endoplasmic reticulum (ER) stress, we also analyzed phospholipid rearrangements in EVs released by Huh-7 cells treated with thapsigargin, a conventional ER stress inducer. Results demonstrate that lipotoxic and/or ER stress conditions induced rearrangements not only into cell membrane phospholipids but also into the released EVs. Thus, cell membrane saturation level and/or ER stress are crucial to determine which lipids are discarded via EVs and EV lipid cargos might be useful to discriminate hepatic lipid overloading and ER stress.

Oxygen isotopic analysis of the size fraction between 62 and 250 micrometers in Caribbean cores p6304-8 and p6304-9.

Oxygen isotopic analysis of the carbonate sediment fraction between 62 and 250 micrometry yields curves following the general trend of those obtained from Globigerinoides sacculifera. Warm stages 11, 13, and 15 are characterized by heavy postdepositional solution. which makes the sediment fraction between 62 and 250 micrometers rich in shell fragments of the more resistant, deeper-living species. As a result, oxygen isotopic analysis of these samples yields comparatively low temperatures, in contrast to those obtained from Globigerinoides sacculifera.

Pleistocene paleotemperatures.

The generalized isotopic paleotemperature curve reproduces absolute temperatures to within 1 degrees C; it closely reflects faunal changes; and its time scale is correct to within a very few percent back to at least 175,000 years. The average oxygen isotopic composition of the North American and European ice caps was about -9 per mil.

Quaternary paleotemperatures and the duration of the high-temperature intervals.

Oxygen isotopic analysis of Caribbean cores P6304-4 and P6304-7, and the close correlation of these cores with other Caribbean and Atlantic cores previously analyzed, make possible the reconstruction of a paleotemperature curve of considerable detail. This curve demonstrates again the unusualness of the present interval of high temperature within the framework of Quaternary climatic evolution, and the need for a close study of man's impact on climate.

Interglacial high sea levels and the control of greenland ice by the precession of the equinoxes.

The precession of the equinoxes appears to control the occurrence of high sea levels by partial or even total melting of the Greenland ice cap during interglacial ages.

The last interglacial: paleotemperatures and chronology.

The O(18)/O(16) analysis and Th(230)/Pa(231) dating of deep-sea cores showed that the last interglacial age, with an early major temperature maximum followed by two smaller ones, extended from 100,000 to 70,000 years ago and was preceded by a glacial age extending from 120,000 to 100,000 years ago. The O(18)/O(16) analysis and Th(230)/U(234) dating of speleothems confirm and refine these ages.

Paleotemperature Variations across the Plio-Pleistocene Boundary.

Strong variations in the O(18)/O(16) and C(13)/C(12) ratios occur through the type section for the Plio-Pleistocene boundary, but the boundary itself is not characterized by unusual isotopic gradients.

Depth habitats of growth stages of pelagic foraminifera.

Oxygen isotopic analysis of different size groups of shells of pelagic foraminiferal species shows that some species deposit their shells at constant depths while others deposit them at increasing or decreasing depths. These patterns show regional variations. Globigerinoides rubra and Globigerinoides sacculifera remain the most convenient species for oxygen isotopic determination of the past surface temperatures of the ocean.

The brunhes epoch: isotopic paleotemperatures and geochronology.

Oxygent isotopic analysis of a long piston core from the western equatorial Pacific has produced a record for the entire Brunhes epoch. This record can be correlated point by point with the isotopic records of previously analyzed Atlantic and Caribbean cores, leading to the construction of a generalized temperature curve for the entire Brunhes epoch.

Absolute dating of Caribbean cores p6304-8 and p6304-9.

Two deep-sea cores from the central Caribbean have been dated by the thorium-230/ protactinium-231 method. The ages obtained are in agreement with the ages previously obtained from other deep-sea cores from the same area. Because of their greater precision, the new dates provide a more accurate time scale for the past 170,000 years.

Oxygen-isotope analysis of recent tropical Pacific benthonic Foraminifera.

Analysis by the oxygen-isotope method of samples of benthonic Foraminifera, collected at different depths on the continental shelf and slope of western Cenitral America, yielded isotopic temperatures agreeing closely with the temperatures measured in the field. The validity of the oxygen-isotope method as a means of analysis of paleotemperatures is further supported.

Underground nuclear explosions and the control of earthquakes.

Underground nuclear explosions trigger significant earthquake activity for at least 32 hours afterward and to distances up to at least 860 kilometers. The proposed Amchitka test may be used to study the feasibility of employing high-yield underground nuclear explosions to release stresses accumulating in the lithosphere. Periodical explosions along active fault zones may be used to prevent disastrous earthquakes.

Final desiccation of the afar rift, ethiopia.

Stable and radioactive isotope studies of ancient corals and mollusks from a fossil atoll in the Afar Rift indicate that final separation of the Afar Depression from the Red Sea occurred not earlier than 32,000 years ago. Desiccation followed within a few thousand years. The events recorded in the Afar Rift illustrate the processes occurring in the incipient stages leading to the formation of an oceanic body by rifting of a continental block.

Oxygen and carbon isotopic growth record in a reef coral from the Florida keys and a deep-sea coral from blake plateau.

Carbon and oxygen isotope analysis through a 30-year (1944 to 1974) growth of Montastrea annularis from Hen and Chickens Reef (Florida Keys) shows a strong yearly variation in the abundances of both carbon-13 and oxygen-18 and a broad inverse relationship between the two isotopes. Normal annual dense bands are formed during the summer and are characterized by heavy carbon and light oxygen. "Stress bands" are formed during particularly severe winters and are characterized by heavy carbon and heavy oxygen. The isotopic effect of Zooxanthellae metabolism dominates the temperature effect on the oxygen-18/oxygen-16 ratio. The isotopic results on the deep-sea solitary coral Bathypsammia tintinnabulum, where Zooxanthellae are nonexistent, indicates that the abundance of the heavy isotopes carbon-13 and oxygen-18 is inversely related to the growth rate, with both carbon and oxygen approaching equilibrium values with increasing skeletal age.

Little salt spring, Florida: a unique underwater site.

Little Salt Spring in southwest Florida, consisting of a shallow, water-filled basin above a deep, vertical underwater cavern, was a freshwater cenote in the peninsula's drier past. It collected and preserved perishable organic artifacts and other evidence of Paleo-Indian and Archaic Indian origin ranging in age from 12,000 to 9000 and from 6800 to 5200 years ago. An Archaic Period cemetery containing an estimated 1000 burials occupies an adjoining muck-filled slough and presently drowned portions of the basin of the spring. Artifacts and the nature of interment suggest a cultural link between the Archaic people and the much later Glades Tradition of southern Florida.

Paleoclimatological analysis of late quaternary cores from the northeastern gulf of Mexico.

Oxygen isotopic, radiocarbon, and micropaleontological analysis of deep-sea cores from the northeastern Gulf of Mexico identify an episode of rapid ice melting and sea-level rise at about 9600 years B.C. This age coincides, within the limits of all errors, with the age of the Valders ice readvance and with the age assigned by Plato to the flood he describes.

Enhancement of lysosomal glycohydrolase activity in human primary B lymphocytes during spontaneous apoptosis.

It has been shown that lysosomes are involved in B cell apoptosis but lysosomal glycohydrolases have never been investigated during this event. In this study we determined the enzymatic activities of some lysosomal glycohydrolases in human tonsil B lymphocytes (TBL) undergoing in vitro spontaneous apoptosis. Fluorimetric methods were used to evaluate the activities of beta-hexosaminidases, alpha-mannosidase, beta-mannosidase, alpha-galactosidase, beta-glucuronidase and alpha-fucosidase. Results show that in TBL during spontaneous apoptosis, there is a significant increase in the activity of beta-hexosaminidases, alpha-mannosidase, beta-mannosidase and beta-galactosidase. Also beta-glucuronidase and alpha-fucosidase activities increase but not in a significant manner. Further studies on beta-hexosaminidases revealed that also mRNA expression of the alpha- and beta-subunits, which constitute these enzymes, increases during spontaneous TBL apoptosis. When TBL are protected from apoptosis by the thiol molecule N-acetyl-L-cysteine (NAC), there is no longer any increase in glycohydrolase activities and mRNA expression of beta-hexosaminidase alpha- and beta-subunits. This study demonstrates for the first time that the activities and expression of some lysosomal glycohydrolases are enhanced in TBL during spontaneous apoptosis and that these increases are prevented when TBL apoptosis is inhibited.

Cryopreservation of cells: FT-IR monitoring of lipid membrane at freeze-thaw cycles.

In the present study, FTIR spectroscopy was used to monitor the freeze-thaw cycle of two cellular lines (HuDe and Jurkat) suspended in three different media: phosphate buffer solution (PBS); dimethylsulfoxide (DMSO)/PBS solution at 0.1 DMSO molar fraction; and CryoSure (0.1 DMSO molar fraction PBS solution+dextran 5% w/v) solution. The Trypan Blue test was also applied before freezing and after thawing each cell sample to estimate the recovery of membrane integrity after thermal treatment, and correlate this datum with spectroscopic results. By following the temperature evolution of two different spectral components (the libration and bending combination mode νc(H2O) at 2000-2500 cm(-1), and the methylene symmetric stretching vibration νsym(CH2) at about 2850 cm(-1)) in the -120÷28°C range, we evidenced the main transition of lipid membrane in connection with cell dehydration, as induced by ice formation in the extracellular medium. In particular, in DMSO/PBS and CryoSure samples we observed a transition to a more rigid state of the lipid membrane together with an increased amount of non-freezable water in the extracellular medium; these results are connected to the role of DMSO as a cryoprotective agent irrespective of the nature of cell type.