bluuebunny/crossref_metadata_2025_split huggingface dataset:
KINESIN‐LIKE PROTEINS ARE INVOLVED IN POSTMITOTIC NUCLEAR MIGRATION OF THE UNICELLULAR GREEN ALGA MICRASTERIAS DENTICULATA
Authors: Holzinger Andreas , Lütz‐Meindl Ursula 
Published: August 2002

AbstractThe unicellular green alga Micrasterias denticulata performs a two‐directional postmitotic nuclear migration during development, a passive migration into the growing semicell, and a microtubule mediated backward migration towards the cell centre. The present study provides first evidence for force generation by motor proteins of the kinesin family in this process. The new kinesin specific inhibitor adociasulfate‐2 causes abnormal nuclear displacement at 18μM. AMP‐PNP, a non hydrolyseable ATP analogue or the general ATPase inhibitors calyculin A and sodium orthovanadate also disturb nuclear migration.In addition kinesin‐like proteins are detected by means of immunoblotting using antibodies against brain kinesin, plant derived antibodies to kinesin‐like proteins and a calmodulin binding kinesin‐like protein. Immunoelectron microscopy suggests a correlation of conventional kinesin‐like proteins, but not of the calmodulin binding kinesin‐like protein to the microtubule apparatus associated with the migrating nucleus.
β‐ENDORPHIN IN GRANULOCYTES
Authors: Csaba G. , Kovács P. , Pállinger Éva 
Published: August 2002

AbstractThe literature indicates that β‐endorphin can be found in the mononuclear cells of peripheral blood. In the present experiments the endorphin content of granulocytes was studied, compared to lymphocytes as reference cells. Granulocytes as well, as lymphocytes contain endorphin. The granulocytes' endorphin content is much higher. Both lymphocytes and granulocytes are also able to take up endorphin from the milieu.
OVEREXPRESSION OF CYCLIN D1 IS ASSOCIATED WITH THE DECONDENSATION OF CHROMATIN DURING DEN‐INDUCED SEQUENTIAL HEPATOCARCINOGENESIS
Authors: Sundarrajan Monisha , Gupta Sanjay , Rao K. V. K. 
Published: August 2002

AbstractD‐type cyclins regulate distinct cellular processes such as mitotic cell cycle control, differentiation and transcription. Deregulation of cyclin D1, a component of G1 checkpoint control, can result in enhanced genomic instability, cell transformation, and malignant neoplasia. However, a precise understanding of the molecular and cellular events underlying the regulation of the cyclin D1 gene remains to be elucidated. In this study, we examined the regulation of the cyclin D1 gene during n‐nitrosodiethylamine (DEN)‐induced sequential liver carcinogenesis. Northern blot studies showed an increase in the level of cyclin D1 mRNA. Southern blot analysis of the DNA restriction fragment showed no alterations and/or amplification in the coding region of the cyclin D1 gene. Bulk chromatin from DEN‐treated rat liver is much more sensitive to nuclease digestion than that from normal liver. Increased expression of the cyclin D1 gene is correlated to the upregulation of its transcription, mediated through chromatin decondensation during sequential hepatocarcinogenesis. Thus, the functional inter‐relationship between chromatin organization and gene expression appears to be of critical importance for liver tumour development.
DNA STRAND‐BREAKS INDUCED BY THE TOPOISOMERASE I INHIBITOR CAMPTOTHECIN IN UNSTIMULATED HUMAN WHITE BLOOD CELLS
Authors: Daza P. , Torreblanca J. , García‐Herdugo G. , Moreno F. J. 
Published: August 2002

AbstractCamptothecin (CPT) and actinomicyn‐induced strand‐breaks, repair and apoptosis in unstimulated human blood cells were studied using the DNA comet assay, and electrophoresis of low molecular weight DNA extracts. On the one hand, incubation of G0 leukocytes for 1h with CPT induced DNA strand‐breaks that were observed using the single cell gel electrophoresis technique. On the other hand, internucleosomal DNA fragments were not observed, suggesting that apoptosis had not occurred. DNA‐strand‐breaks caused by CPT were repaired 24h after treatment; the migration of DNA fragments was assessed by a reduction in the number of comets. These data strongly suggest that the unexpected clastogenic effect of this topoisomerase I inhibitor is not due to the collision of the cleavage complex with the replication fork, since replication does not occur in G0. In our opinion, this effect could be due instead to the topoisomerase I enzyme being able to bind DNA in the absence of replication, probably in a way that is not strictly related to the progression of the cell cycle. Thus, CPT does not provoke apoptosis in quiescent leukocytes.
REAPPRAISAL OF G1‐PHASE ARREST AND SYNCHRONIZATION BY LOVASTATIN
Authors: Cooper Stephen 
Published: August 2002

AbstractIt has been proposed that lovastatin arrests cells in the G1‐phase of the division cycle, and that release from lovastatin inhibition produces a synchronized culture. A new method of methocel time‐lapse‐videography has been used to analyse cell division patterns following lovastatin treatment. Release of L1210 cells from lovastatin inhibition failed to produce synchronized divisions. Moreover, contrary to earlier proposals, lovastatin did not arrest cells with a G1‐phase amount of DNA. Analysis of previous reports of ‘synchronization’ and growth‐arrest support these findings. It is concluded that lovastatin neither synchronizes cells, nor arrests cells in the G1‐phase of the division cycle.
Combined Marine Proxy and Pollen Analyses Reveal Rapid Iberian Vegetation Response to North Atlantic Millennial-Scale Climate Oscillations
Authors: Roucoux Katherine H. , Shackleton Nicholas J. , de Abreu Lucia , Schönfeld Joachim , Tzedakis Polychronis C. 
Published: August 2002

AbstractA deep-sea sediment core from the western Portuguese margin has provided a continuous, high-resolution record of millennial-scale climatic oscillations during the interval 9000–65,000 yr B.P. Pollen analysis of the same sequence allows direct, in situ assessment of the phase relationship between the North Atlantic climate system and vegetation changes on the adjacent landmass. This demonstrates for the first time that variability in NW Iberian tree population size closely tracked millennial-scale climate variability.
Subdivision of Glacial Deposits in Southeastern Peru Based on Pedogenic Development and Radiometric Ages
Authors: Goodman Adam Y. , Rodbell Donald T. , Seltzer Geoffrey O. , Mark Bryan G. 
Published: August 2002

AbstractThe Cordillera Vilcanota and Quelccaya Ice Cap region of southern Peru (13°30′–14°00′S; 70°40′–71°25′W) contains a detailed record of late Quaternary glaciation in the tropical Andes. Quantification of soil development on 19 moraine crests and radiocarbon ages are used to reconstruct the glacial history. Secondary iron and clay increase linearly in Quelccaya soils and clay accumulates at a linear rate in Vilcanota soils, which may reflect the semicontinuous addition of eolian dust enriched in secondary iron to all soils. In contrast, logarithmic rates of iron buildup in soils in the Cordillera Vilcanota reflect chemical weathering; high concentrations of secondary iron in Vilcanota tills may mask the role of eolian input to these soils. Soil-age estimates from extrapolation of field and laboratory data suggest that the most extensive late Quaternary glaciation occurred >70,000 yr B.P. This provides one of the first semiquantitative age estimates for maximum ice extent in southern Peru and is supported by a minimum-limiting age of ∼41,520 14C yr B.P. A late glacial readvance culminated ∼16,650 cal yr B.P. in the Cordillera Vilcanota. Following rapid deglaciation of unknown extent, an advance of the Quelccaya Ice Cap occurred between ∼13,090 and 12,800 cal yr B.P., which coincides approximately with the onset of the Younger Dryas cooling in the North Atlantic region. Moraines deposited <394 cal yr B.P. in the Cordillera Vilcanota and <300 cal yr B.P. on the west side of the Quelccaya Ice Cap correlate with Little Ice Age moraines of other regions.
Evolution of Soils on Quaternary Reef Terraces of Barbados, West Indies
Authors: Muhs Daniel R. 
Published: August 2002

AbstractSoils on uplifted Quaternary reef terraces of Barbados, ∼125,000 to ∼700,000 yr old, form a climo-chronosequence and show changes in physical, chemical, and mineralogical properties with terrace age. Parent materials are dust derived from the Sahara, volcanic ash from the Lesser Antilles island arc, and detrital carbonate from the underlying reef limestone. Although some terrace soils are probably eroded, soils or their remnants are redder and more clay-rich with increasing terrace age. Profile-average Al2O3 and Fe2O3 content increases with terrace age, which partially reflects the increasing clay content, but dithionite-extractable Fe also increases with terrace age. Profile-average K2O/TiO2, Na2O/TiO2, and P2O5/TiO2 values decrease with terrace age, reflecting the depletion of primary minerals. Average SiO2/Al2O3 values also decrease with terrace age and reflect not only loss of primary minerals but also evolution of secondary clay minerals. Although they are not present in any of the parent materials, the youngest terrace soils are dominated by smectite and interstratified kaolinite-smectite, which gradually alter to relatively pure kaolinite over ∼700,000 yr. Comparisons with other tropical islands, where precipitation is higher and rates of dust fall may be lower, show that Barbados soils are less weathered than soils of comparable age. It is concluded that many soil properties in tropical regions can be potentially useful relative-age indicators in Quaternary stratigraphic studies, even when soils are eroded or changes in soil morphology are not dramatic.
Mineralogic and Climatic Interpretations of the Luochuan Loess Section (China) Based on Diffuse Reflectance Spectrophotometry
Authors: Ji Junfeng , Balsam William , Chen Jun 
Published: August 2002

AbstractWe examined the top 135 m, that is, the entire Pleistocene, of the classic Luochuan section on the Chinese Loess Plateau with a diffuse reflectance spectrophotometer from the near ultraviolet, through the visible, and into the near infrared. From the reflectance data we calculated sample brightness which, with some caveats, is a reasonable proxy for magnetic susceptibility. Mineralogic changes were identified by factor analyzing the first derivative of the percent reflectance data and examining samples with high factor scores. Two factors which explain about 96% of the cumulative variance are distinguished by the relative proportion of hematite and goethite, the minerals that are responsible for the color changes in the loess sequence. Both hematite and goethite are present in both loess and paleosol but goethite dominates in loess whereas hematite dominates in paleosol. The goethite factor exhibits an inverse correlation with magnetic susceptibility; the hematite factor exhibits a weak positive correlation with susceptibility. Paleoclimatic interpretations are drawn from comparison of susceptibility to the concentration of spectrally identified hematite. Based on this comparison, paleosols in the early Pleistocene Wucheng Formation are characterized by conditions that are drier than today, a “dry summer monsoon”, whereas later Pleistocene paleosols are characterized by a “wet summer monsoon”.
Holocene Vegetation Dynamics of Anticosti Island, Québec, and Consequences of Remoteness on Ecological Succession
Authors: Lavoie Martin , Filion Louise 
Published: August 2002

AbstractThe postglacial vegetation history of Anticosti Island in the Gulf of St. Lawrence, Québec, was reconstructed from pollen analysis of three sites, providing the first paleoecological data for the island. The earliest plant communities (8550–777014C yr B.P.; 9500–8500 cal yr B.P.) were characterized by a high representation of green alder (Alnus crispa), indicating an open environment with sparse spruce (Picea). Between 7770 and 370014C yr B.P. (8500–4000 cal yr B.P.), the island was colonized by mixed deciduous and coniferous forests dominated by paper birch (Betula papyrifera) and spruce. A major increase in the abundance of balsam fir (Abies balsamea) occurred ca. 370014C yr B.P. (4000 cal yr B.P.), indicating development of the closed fir–spruce forests as they exist today. The island's remoteness from continental seed plant sources influenced plant colonization, afforestation, and ecological succession. The Gulf of St. Lawrence slowed plant migration, and tree species had to spread from the Gaspé Peninsula. Repeated drops in fir pollen percentages during the last 4,000 years may reflect the activity of defoliating insects.
Late Pleistocene Detrital Sediment Yield of the Jura Glacier, France
Authors: Buoncristiani Jean-François , Campy Michel 
Published: August 2002

AbstractMeasures of present-day glacial erosion vary widely with the technique employed. This paper quantifies the glacial material trapped in a proglacial lake during the Würm glacial period. The Combe d'Ain site was occupied by a meltwater lake where all the detrital material entering it from the Jura glacier accumulated. Sediment yield is computed from three factors: (1) the size of the sediment source area, (2) the length of time the system operated, and (3) the volume of sediment trapped. The sediment budget of the lake system suggests a detrital sediment yield of 4400±1700 metric tons per square kilometer and per calendar year. This represents a denudation rate of 1.6±0.6 mm per year, illustrating that mechanical erosion by the Jura glacier is more intensive than other processes of erosion.
Late Quaternary Climate and Hydrology of Tropical South America Inferred from an Isotopic and Chemical Model of Lake Titicaca, Bolivia and Peru
Authors: Cross Scott L. , Baker Paul A. , Seltzer Geoffrey O. , Fritz Sherilyn C. , Dunbar Robert B. 
Published: August 2002

AbstractA simple mass balance model provides insight into the hydrologic, isotopic, and chemical responses of Lake Titicaca to past climatic changes. Latest Pleistocene climate of the Altiplano is assumed to have been 20% wetter and 5°C colder than today, based on previous modeling. Our simulation of lacustrine change since 15,000 cal yr B.P. is forced by these modeled climate changes. The latest Pleistocene Lake Titicaca was deep, fresh, and overflowing. The latest Pleistocene riverine discharge from the lake was about 8 times greater than the modern average, sufficient to allow the expansion of the great paleolake Tauca on the central Altiplano. The lake δ18O value averaged about −13‰ SMOW (the modern value is about −4.2‰). The early Holocene decrease in precipitation caused Lake Titicaca to fall below its outlet and contributed to a rapid desiccation of paleolake Tauca. Continued evaporation caused the 100-m drop in lake level, but only a slight (1–2‰) increase (relative to modern) in δ18O of early Holocene lake waters. This Holocene lowstand level of nearly 100 m was most likely produced by a precipitation decrease, relative to modern, of about 40%. The lake was saline as recently as 2000 cal yr B.P. The timing of these hydrologic changes is in general agreement with calculated changes of insolation forcing of the South American summer monsoon.
Evidence for Millennial-Scale Climate Change During Marine Isotope Stages 2 and 3 at Little Lake, Western Oregon, U.S.A.
Authors: Grigg Laurie D. , Whitlock Cathy , Dean Walter E. 
Published: August 2002

AbstractPollen and geochemical data from Little Lake, western Oregon, suggest several patterns of millennial-scale environmental change during marine isotope stage (MIS) 2 (14,100–27,600 cal yr B.P.) and the latter part of MIS 3 (27,600–42,500 cal yr B.P.). During MIS 3, a series of transitions between warm- and cold-adapted taxa indicate that temperatures oscillated by ca. 2°–4°C every 1000–3000 yr. Highs and lows in summer insolation during MIS 3 are generally associated with the warmest and coldest intervals. Warm periods at Little Lake correlate with warm sea-surface temperatures in the Santa Barbara Basin. Changes in the strength of the subtropical high and the jet stream may account for synchronous changes at the two sites. During MIS 2, shifts between mesic and xeric subalpine forests suggest changes in precipitation every 1000–3000 yr. Increases in Tsuga heterophylla pollen at 25,000 and 22,000 cal yr B.P. imply brief warmings. Minimum summer insolation and maximum global ice-volumes during MIS 2 correspond to cold and dry conditions. Fluctuations in precipitation at Little Lake do not correlate with changes in the Santa Barbara Basin and may be explained by variations in the strength of the glacial anticyclone and the position of the jet stream.
Late Quaternary Vegetation and Climatic History of the Long Valley Area, West-Central Idaho, U.S.A.
Authors: Doerner James P. , Carrara Paul E. 
Published: August 2002

AbstractPaleoenvironmental data, including pollen and sediment analyses, radiocarbon ages, and tephra identifications of a core recovered from a fen, provide a ca. 16,500 14C yr B.P. record of late Quaternary vegetation and climate change in the Long Valley area of west-central Idaho. The fen was deglaciated prior to ca. 16,500 14C yr B.P., after which the pollen rain was dominated by Artemisia, suggesting that a cold, dry climate prevailed until ca. 12,200 14C yr B.P. From ca. 12,200 to 9750 14C yr B.P. temperatures gradually increased and a cool, moist climate similar to the present prevailed. During this period a closed spruce–pine forest surrounded the fen. This cool, moist climate was briefly interrupted by a dry and/or cold interval between ca. 10,800 and 10,400 14C yr B.P. that may be related to the Younger Dryas climatic oscillation. From ca. 9750 to 3200 14C yr B.P. the regional climate was significantly warmer and drier than at present and an open pine forest dominated the area around the fen. Maximum aridity occurred after the deposition of the Mazama tephra (ca. 6730 14C yr B.P.). After 3200 14C yr B.P. regional cooling brought cool, moist conditions to the area; the establishment of the modern montane forest around the fen and present-day cool and moist climate began at ca. 2000 14C yr B.P.
The First Dated Eemian Lacustrine Deposit in Romania
Authors: Petroniu Onac Bogdan , Björkman Leif , Björck Svante , Clichici Octavian , Tamas Tudor , Peate David , Wohlfarth Barbara 
Published: August 2002

AbstractA complex interglacial sequence of lacustrine sediments has been found near the village of Turbuta in NW Romania. Mollusk, plant macrofossil, and pollen analyses reflect climatic and environmental changes around the last interglacial climatic optimum. U-Th TIMS dating of snails strongly indicates an Eemian age of the organic sediments.
Late Holocene Changes in Precipitation and Hydrography Recorded in Marine Sediments from the Northeastern Caribbean Sea
Authors: Nyberg Johan , Kuijpers Antoon , Malmgren Björn A. , Kunzendorf Helmar 
Published: August 2002

AbstractWe present a record of climate variability spanning the last 2000 years obtained from sediment cores retrieved south and west of Puerto Rico in the northeastern Caribbean Sea. The records include lithological and mineral magnetic parameters as well as planktonic foraminifer data. For chronostratigraphic control, AMS14C and210Pb/137Cs measurements were made. Harmonic analysis of the values of the mineral magnetic parameters “saturation isothermal remanent magnetization” (SIRM), “anhysteric remanent magnetization divided by magnetic susceptibility” (ARM/χ), and “saturation isothermal remanent magnetization divided by magnetic susceptibility” (SIRM/χ) indicate the existence of a ∼200-year-long climate cycle in the northeastern Caribbean during the last 2000 years. The detected cycle may reflect changes in precipitation patterns over the low-latitude North Atlantic Ocean and surrounding continental areas. Higher organic carbon contents appear in the sediments both off southern and western Puerto Rico before and at the onset of the Little Ice Age around A.D. 1300 to 1500. This is indicative of increased run off and/or enhanced surface productivity possibly associated with more intense wind-induced upwelling. Major changes in the geochemical and mineral magnetic records around A.D. 850–1000 concur with changes in other records from the Caribbean and North African regions indicating a shift toward a more humid climate over the low-latitude North Atlantic.
Transport Direction of Peoria Loess in Nebraska and Implications for Loess Sources on the Central Great Plains
Authors: Mason Joseph A. 
Published: August 2002

AbstractIn the midwestern United States, large rivers draining the Laurentide Ice Sheet (LIS) were the most important sources of Peoria Loess, deposited during the last glaciation. Loess deposition near those rivers may have responded primarily to ice-sheet dynamics rather than direct effects of climatic change. In contrast, it has been proposed that thick Peoria Loess on the central Great Plains was derived mainly from unglaciated landscapes northwest of the main loess deposits. In this study, transport directions inferred from more than 600 measurements of Peoria Loess thickness in Nebraska are used to test the hypothesis that much of the Peoria Loess on the Great Plains is nonglaciogenic. A strong northwest to southeast thickness trend indicates that most Peoria Loess in Nebraska was transported from one or more unglaciated northwestern source areas rather than from glacially influenced river floodplains. The Missouri River (draining the LIS), the Platte River (draining alpine glaciers), and the Elkhorn River (unglaciated basin) were secondary sources. Their contribution is not detectable beyond a distance of 40–60 km. Peoria Loess deposition on the central Great Plains was largely a direct response to climatic change in the unglaciated source region.
Last Interglacial Climates
Authors: Kukla George J. , Bender Michael L. , de Beaulieu Jacques-Louis , Bond Gerard , Broecker Wallace S. , Cleveringa Piet , Gavin Joyce E. , Herbert Timothy D. , Imbrie John , Jouzel Jean , Keigwin Lloyd D. , Knudsen Karen-Luise , McManus Jerry F. , Merkt Josef , Muhs Daniel R. , Müller Helmut , Poore Richard Z. , Porter Stephen C. , Seret Guy , Shackleton Nicholas J. , Turner Charles , Tzedakis Polychronis C. , Winograd Isaac J. 
Published: August 2002

AbstractThe last interglacial, commonly understood as an interval with climate as warm or warmer than today, is represented by marine isotope stage (MIS) 5e, which is a proxy record of low global ice volume and high sea level. It is arbitrarily dated to begin at approximately 130,000 yr B.P. and end at 116,000 yr B.P. with the onset of the early glacial unit MIS 5d. The age of the stage is determined by correlation to uranium–thorium dates of raised coral reefs. The most detailed proxy record of interglacial climate is found in the Vostok ice core where the temperature reached current levels 132,000 yr ago and continued rising for another two millennia. Approximately 127,000 yr ago the Eemian mixed forests were established in Europe. They developed through a characteristic succession of tree species, probably surviving well into the early glacial stage in southern parts of Europe. After ca. 115,000 yr ago, open vegetation replaced forests in northwestern Europe and the proportion of conifers increased significantly farther south. Air temperature at Vostok dropped sharply. Pulses of cold water affected the northern North Atlantic already in late MIS 5e, but the central North Atlantic remained warm throughout most of MIS 5d. Model results show that the sea surface in the eastern tropical Pacific warmed when the ice grew and sea level dropped. The essentially interglacial conditions in southwestern Europe remained unaffected by ice buildup until late MIS 5d when the forests disappeared abruptly and cold water invaded the central North Atlantic ca. 107,000 yr ago.