bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cytoskeletal dynamics in living plant cells
Authors: Hepler P. K. , Cleary A. L. , Gunning B. E. S. , Wadsworth P. , Wasteneys G. O. , Zhang D. H. 
Published: October 2002

AbstractMicrotubules and microfilaments have been imaged in living plant cells and their dynamic changes recorded during division, growth and development. Carboxyfluorescein labeled brain tubulin has been injected into cells that are maintained in an active state in a culture chamber on the microscope stage. Subsequent imaging with the confocal microscope reveals microtubules in the preprophase band, the mitotic apparatus, the phragmoplast, and the cortical array. The structural changes of these microtubules have been observed during transitional stages. In addition, their dynamic features are demonstrated by depolymerization in elevated calcium, low temperature, and in the drug oryzalin, and by repolymerization when returned to normal conditions. Examination of living Tradescantia stamen hair cells, which have been injected with fluorescent phalloidin to label the actin microfilaments, reveals hitherto undisclosed aspects of the preparation of the division site and dynamics of the phragmoplast cytoskeleton. During prophase microfilaments occur throughout the cell cortex, with those in the region of the preprophase band becoming transversely aligned. At nuclear envelope breakdown, these specifically disassemble, leaving a circumferential zone from which microfilaments remain absent throughout division. During cytokinesis microfilaments arise within the phragmoplast, oriented parallel to the microtubules, but excluded from the zone where the MTs overlap and where cell plate vesicles aggregate. The phragmoplast microfilaments, in a manner similar to microtubules, shorten in length, expand in girth, and eventually disassemble when the cell plate is complete.
A cell cycle study of human mammary epithelial cells.
Authors: Larsson Olle , Blegen Harald , Wejde Johan , Zetterberg Anders 
Published: October 2002

AbstractThe growth regulation of human mammary epithelial cells (HMEC) cultured in a growth factor/hormone‐enriched (e.g. EGF, insulin) medium with bovine pituitary extract as the only undefined supplement was studied. The doubling times of the cultures, in which the cells appear in colonies, was 55‐72 h, and a considerable intercolonial heterogenecity in proliferative activity could be demonstrated. However, every colony, irrespective of the size of the growth fraction, comprised a sub‐population of rapidly growing cells which had a mean generation time of approximately 22 h. When insulin was removed from the culture medium, HMEC proliferation was inhibited. This growth inhibition was shown to be a result of a cell cycle‐specific block.
Catecholamines in Drosophila melanogaster (wild type and ebony mutant) decuticalarized retinas and brains.
Authors: Ramadan Hassan , Alawi Adnan A. , Alawi Mahmoud A. 
Published: October 2002

AbstractThe concentrations of catecholamines were determined in the decuticalarized retinas and brains at different ages in wildtype and ebony Drosophila melanogaster using the HPLC‐technique with an electrochemical detector. L‐Dopa, dopamine (DA), α‐methyldopa (α‐MD) and unidentified compounds X1, X2 and X3 were found in decuticalarized retinas and brains of wildtype and ebony at different ages. Retinas and brains of the mutant ebony have higher concentrations of L‐Dopa, DA and α‐MD than the wildtype. In both wildtype and ebony, the concentrations of X1, X2 and X3 were found to be higher in decuticalarized retinas than in brains. The identity and importance of X1, X2 and X3 are still unknown.
Extracts from MDX and normal mouse skeletal muscle contain similar levels of mitogenic activity for myoblasts
Authors: Chen Gang , Bressler Bernard H. , Quinn LeBris S. 
Published: October 2002

ABSTRACTThe mdx mouse has been used as an animal model for human Duchenne muscular dystrophy (DMD). Unlike DMD, skeletal muscles of mdx mice undergo successful regeneration and do not show extensive fibrosis and functional impairment. Growth factors have been proposed to be involved in muscle growth and regeneration. We compared mitogenic activity for skeletal myoblasts released after injury in mdx and control mice, using crushed muscle extract (CME) as a model system. We found that CMEs from normal and mdx mice contained similar mitogenic activities per microgram protein, and produced similar maximal levels of mitogenic stimulation. Skeletal muscles from mdx mice, however, released higher amounts of CME protein per gram of muscle weight compared to controls, possibly as a result of histological or physiological alterations in mdx muscle tissue. Adequate mitogenic activity in CME from mdx muscles may be related to successful muscle regeneration in mdx mice.
The proton pump of heme‐copper oxidases.
Authors: Papa S. , Capitanio N. , Glaser P. , Villani G. 
Published: October 2002

ABSTRACTProton pumping heme‐copper oxidases represent the terminal, energy‐transfer enzymes of respiratory chains in prokaryotes and eukaryotes. The CuB‐heme a3 (or heme o) binuclear center, associated with the largest subunit I of cytochrome c and quinol oxidases, is directly involved in the coupling between dioxygen reduction and proton pumping. The role of the other subunits is less clear. The following aspects will be covered in this paper:i) the efficiency of coupling in the mitochondrial aa3 cytochrome c oxidase. In particular, the effect of respiratory rate and protonmotive force on the H+/e− stoichiometry and the role of subunit IV; ii) mutational analysis of the aa3 quinol oxidase of Bacillus subtilis addressed to the role of subunit III, subunit IV and specific residues in subunit I; iii) possible models of the protonmotive catalytic cycle at the binuclear center. The observations available suggest that H+/e−coupling is based on the combination of protonmotive redox catalysis at the binuclear center and co‐operative proton transfer in the protein.
Immunohistochemical characterization of a stage‐specific antigen during oogenesis and spermatogenesis recognized with monoclonal antibody
Authors: Itoh Masaaki , Kimura Junpei , Tsukise Azuma , Okano Masaomi 
Published: October 2002

ABSTRACTIn order to detect and characterize novel molecules which function in oogenesis, immunohistochemical study using a monoclonal antibody (MAb) raised against oocytes of Xenopus laevis was carded out. The distribution of the detectable molecule with MAb X‐80, which specifically reacts with Xenopus previtellogenic oocytes; stages I and II (Dumont, 1972), in particular was analyzed. The hamster, mouse, chick, quail, Caenorhabditis elegans and Lilium longiflorum were also examined. Interestingly MAb X‐80 bound not only in Xenopus oocytes but in its secondary spermatocytes and spermatids. Furthermore, MAb X‐80 gave a similar staining pattern in the Lilium and other, although the stage when the positive reaction is detectable is different in the male and female germ cells.
Alkaline phosphatase distribution in the plasma membrane of uterine epithelial cells is markedly altered during early pregnancy in the rat
Authors: Bucci Maria , Murphy Christopher R. 
Published: October 2002

AbstractUltrastructural and light microscopic cytochemical methods were used to study the distribution and changes in distribution of alkaline phospatase in the apical plasma membrane of rat uterine epithelial cells during different stages of early pregnancy up to the time of attachment of the blastocyst. Reaction product generated by alkaline phosphatase (AP) was located along the apical plasma membrane at each stage investigated. However, a very different organization of reaction product was observed depending on the time during early pregnancy with a continuous pattern appearing all along the microvilli on day 1. This pattern was subsequently converted into a clumped and highly ‘patchy’ appearance around the time of blastocyst attachment by day 6 of pregnancy. This change in pattern and distribution was only seen on the luminal epithelial cells with glandular epithelial cells and blood vessels displaying an unchanging distribution.
Characterization of two human cAMP‐specific phosphodiesterase subtypes expressed in baculovirus‐infected insect cells.
Authors: Amegadzie Bernard Y. , Hanning Charles R. , McLaughlin Megan M. , Burman Miriam , Cieslinski Lenora B. , Livi George P. , Torphy Theodore J. 
Published: October 2002

AbstractRecombinant baculoviruses were constructed to express cDNAs encoding two distinct subtypes of human cAMP‐specific phosphodiesterase (hPDE4A and hPDE4B). Infection of Spodoptera frugiperda insect cells with the appropriate recombinant baculoviruses resulted in high level production of biologically‐active protein as measured by enzymatic activity and immunoblotting using subtype‐specific anti‐hPDE4 antisera. Both recombinant proteins showed catalytic activity with a low Km (∼ 3 μM) for cAMP (with no cGMP hydrolyzing activity) and were inhibited by R‐rolipram with apparent Kis of 0.38 and 0.25 μM, respectively. The recombinant enzymes also contained saturable, stereoselective and high‐affinity rolipram‐binding sites (Kd ∼ 2 nM). Thus, insect cell‐derived hPDE4s possess kinetic properties analogous to native enzymes as well as to recombinant enzymes produced in yeast.
INSULIN‐MEDIATED TYROSINE PHOSPHORYLATION OF MYOSIN HEAVY CHAIN AND CONCOMITANT ENHANCED ASSOCIATION OF C‐TERMINAL SRC KINASE DURING SKELETAL MUSCLE DIFFERENTIATION
Authors: Goel Hira Lal , Dey Chinmoy Sankar 
Published: October 2002

AbstractIn this study, we present for the first time: (1) evidence regarding tyrosine phosphorylation of myosin heavy chain, (2) evidence that insulin can phosphorylate myosin, (3) association of myosin with Csk, a signalling molecule, (4) modulation of this association by insulin, and (5) evidence that these interactions are associated with skeletal muscle differentiation.
SPATIAL DISTRIBUTION OF mDLG6 mRNA IN EMBRYONIC AND ADULT MOUSE BRAIN
Authors: Inagaki Hidetoshi , Tanaka Kimiko , Takada Mayuko , Maeda Sumio , Ichihara Shigeyuki , Saito Takao 
Published: October 2002

AbstractWe have isolated mouse DLG6 (mDLG6) cDNA clones by RT‐PCR and then by using the RT‐PCR products to screen a mouse brain cDNA library. The deduced amino acid sequence of mDLG6 shows 79.2% and 82.7% overall identity to human (hDLG6) and rat DLG6 (rDLG6), respectively. In situ hybridization revealed that mDLG6 mRNA is predominantly expressed in embryonic and adult brain.
Influences of Relative Sea-Level Rise and Mississippi River Delta Plain Evolution on the Holocene Middle Amite River, Southeastern Louisiana
Authors: Autin Whitney J. 
Published: October 2002

AbstractThe Holocene geomorphic history of southeastern Louisiana's middle Amite River is recorded in the stratigraphy of three alloformations, identified in decreasing age as the Watson (WAT), Denham Springs (DS), and Magnolia Bridge (MAG). The WAT meander belt formed by at least 9000 yr B.P., when sea level was lower and the Amite River was tributary to a larger ancestral drainage basin. The DS became an active meander belt by at least 3000 yr B.P., in response to relative sea-level rise and eastward progradation of the Mississippi River delta plain. The MAG developed its meander belt, in part, during the European settlement of the drainage basin, and is now attempting to adjust to modern anthropogenic influences. Geomorphic influences on the middle Amite River floodplain have temporal and spatial components that induce regional- and local-scale effects. Regional extrinsic influences caused meander belt avulsion that produced alloformations. However, local influences produced intrinsic geomorphic thresholds that modified channel morphology within a meander belt but did not induce alloformation development. Base-level influences of the relative sea-level rise and the Mississippi River delta plain were so dominant that the effects of possible climate change were not recognized in the Holocene Amite River system.
Spatial Variations of Holocene Climatic Change in the Yellowstone Region
Authors: Whitlock Cathy , Bartlein Patrick J. 
Published: October 2002

AbstractThe paleoecologic record of the northern Rocky Mountains shows considerable spatial variability, which has been difficult to explain as a unified response to large-scale changes in effective moisture or temperature through time. Comparison of past and present climatic patterns suggests that the spatial heterogeneity in the fossil record arises from a local response to the effects of greater summer solar radiation during the early Holocene. Solar radiation directly determines evapotranspiration and indirectly controls the strength of the summer monsoon and the eastern Pacific subtropical high-pressure system. The Yellowstone region provides an example of an area where the indirect effects of solar radiation are manifest by the juxtaposition of two contrasting climatic regimes today and where these regimes were amplified during the early Holocene. Fossil-pollen data suggest that central and southern Yellowstone (the summer-dry area) became drier in the early Holocene, while northern Yellowstone (the summer-wet area) became wetter. The boundary between regimes, however, is controlled by topography and has not changed significantly in the Holocene. The spatial variations of Holocene vegetation and climatic changes in the northern Rocky Mountains may therefore be explained as a trade-off between strengthened monsoonal circulation and a stronger subtropical high in the early Holocene and the relative importance of these precipitation regimes on a topographically complex landscape.
Timing of Late Quaternary Glaciations in the Western United States Based on the Age of Loess on the Eastern Snake River Plain, Idaho
Authors: Forman Steven L. , Smith Richard P. , Hackett William R. , Tullis Julie A. , McDaniel Paul A. 
Published: October 2002

AbstractThe most viable sources for ubiquitous loess deposits on the eastern Snake River Plain, Idaho are aggraded river valleys, active alluvial fans, and fluctuating pluvial lake margins associated with regional late Pleistocene glaciation of the northern Rocky Mountains. Stratigraphic studies on the Idaho National Engineering Laboratory document two distinct loess deposits, separated by a well-developed paleosol, resting on basaltic lava. Baked sediments beneath this lava yielded thermoluminescence (TL) age estimates of 108,000 ± 13,000 and 101,000 ± 7000 yr, and baked organic matter gave radiocarbon ages of >32,000 yr B.P., consistent with an earlier K/Ar age for the flow of 95,000 ± 25,000 yr. The overlying two loess deposits yielded TL age estimates of 74,000 ± 6000 and 28,000 ± 3000 yr. The available geochronology indicates that the latest period of loess deposition commenced ca. 40,000 to 35,000 yr ago and ceased approximately 10,000 yr ago, which is generally coincident with the inferred timing of regional Pinedale glaciation and pluvial lake expansion. We estimate that the penultimate loess depositional episode dates between 80,000 and 60,000 yr ago, which is significantly younger than previous age estimates of 140,000 to 150,000 yr based on stratigraphic position. We speculate that this period of loess deposition may correlate with documented early to middle Wisconsinan glaciation and a high stand of pluvial lakes in the Basin and Range province.
Quantitative Refinement of Calibrated14C Distributions
Authors: Biasi Glenn P. , Weldon Ray 
Published: October 2002

AbstractA new method is presented for using known ordering or other relationships between14C samples to reduce14C dating uncertainty. The order of sample formation is often known from, for example, stratigraphic superposition, dendrochronology, or crosscutting field relations. Constraints such as a minimum time between dates and limits from historical information are also readily included. Dendrochronologically calibrated calendric date histograms initially represent each date. The method uses Bayes theorem and the relational constraints to upweight date ranges in each date distribution consistent with the other date distributions and the constraints, and downweight unlikely portions. The reweighted date distributions retain all dating possibilities present in the initial calibrated date distributions, but each date in the result now reflects the extra information such as ordering supplied through the constraints. In addition, one may add information incrementally, and thus analyze systematically its effect on all the date distributions. Thus, the method can be used to assess the consistency of the quantitative data at hand. The Bayesian approach also uses the empirical calibrated date distributions directly, so information is not lost prematurely by summarized dates to a mean and variance or "confidence intervals." The approach is illustrated with data from two densely sampled paleoseismic sites on the San Andreas Fault in southern California. An average reduction in14C date distribution variance of 59% is achieved using ordering information alone, and 85% is achieved by also applying sedimentation rate constraints and historical information.
Paleoclimatic Implications of Holocene Plant Remains from the Sierra Bacha, Sonora, Mexico
Authors: Van Devender Thomas R. , Burgess Tony L. , Piper Jessie C. , Turner Raymond M. 
Published: October 2002

AbstractA total of 93 plant taxa were identified from 11 packrat (Neotomasp.) midden samples from the Sierra Bacha on the coast of the Gulf of California near Puerto Libertad, Sonora, Mexico. Nine indurated samples have radiocarbon dates ranging from 9970 to 320 yr B.P. Sonoran desertscrub was present on rocky slopes throughout the Holocene. Early Holocene assemblages dominated byFouquieria columnaris(boojum tree) reflect vegetation and climate more like modern Baja California with greater winter rainfall and cooler summers. Middle Holocene vegetation was essentially modern with modest indications of greater monsoonal rainfall even though cold-water upwelling locally inhibits summer precipitation. The results are similar to all previous midden reconstructions of early and middle Holocene climates in the Sonoran Desert, but contradict general atmospheric circulation model simulations.
Climatic Implications of the Late Quaternary Alluvial Record of a Small Drainage Basin in the Central Great Plains
Authors: Arbogast Alan F. , Johnson William C. 
Published: October 2002

AbstractFour late-Quaternary alluvial fills and terraces are recognized in Wolf Creek basin, a small (163 km2) drainage in the Kansas River system of the central Great Plains. Two terraces were created during the late Pleistocene: the T-4 is a fill-top terrace underlain by sand and gravel fill (Fill I), and the T-3 is a strath terrace cut on the Cretaceous Dakota Sandstone. Both Fill II (early Holocene) and Fill III (late Holocene) are exposed beneath the T-2, a Holocene fill-top terrace. The T-1 complex, consisting of one cut and three fill-top terraces, is underlain by Fills III and IV. A poorly developed floodplain (T-0) has formed within the past 1000 yr. As valleys in Wolf Creek basin filled during the early Holocene, an interval of soil formation occurred about 6800 yr B.P. Early Holocene fill has been found only in the basin's upper reaches, indicating that extensive erosion during the middle Holocene removed most early-Holocene fill from the middle and lower reaches of the basin. Valley filling between 5000 and 1000 yr B.P. was interrupted by soil formation about 1800, 1500, and 1200 yr B.P. As much as 6 m of entrenchment has occurred in the past 1000 yr. Holocene events in Wolf Creek basin correlate well with those in other localities in the central Great Plains, indicating that widespread changes in climate, along with adjustments driven by complex response, influenced fluvial activity.
A Biota Associated with Matuyama-Age Sediments in West-Central Illinois
Authors: Miller Barry B. , Graham Russell W. , Morgan Alan V. , Miller Norton G. , McCoy William D. , Palmer Donald F. , Smith Alison J. , Pilny J. J. 
Published: October 2002

AbstractA fossil assemblage containing molluscs, mammals, insects, ostracodes, and plants has been recovered from a silt-filled depression near Lima, in west-central Illinois. The reversed remanent magnetic signature of the sediments and the temporal ranges of two mammals,Microtus paroperariusandLasiopodomys deceitensis,constrain the age of the assemblage to between 730,000 and 830,000 yr B.P. The extent of isoleucine epimerization in the molluscan shell is consistent with this age interpretation. The fauna includes at least 43 taxa of beetles from 11 families, 35 nominal species of molluscs, and two genera of ostracodes. The mammals include two shrews, three rodents, and a rabbit. The plant macrofossils (no pollen recovered) include 25 species of seed plants and four kinds of terrestrial or wetland mosses. Most of the plant species identified still occur in the upper Midwest, although a few of the taxa are found mainly to the north of the site. The fauna is characterized by an almost total absence of true aquatic taxa. The association of both boreal and thermophilous faunal and floral elements suggest that summer temperatures were not greatly different from present ones, but cooler, moist areas must have been available to support the boreal elements. Local conditions were probably similar to those now found in northeastern Iowa, where rains blocks, fissures, and joints in carbonate bedrock serve as traps for debris accumulations, provide shade, and are kept cool and moist during the hot summer months by cold-air drainage and groundwater seepage. Summer mean temperature in these microhabitats was probably between 18 and 20°C, similar to temperatures that now occur near the northern hardwood spruce-fir transition in the eastern United States.
Postglacial Recession of Niagara Falls in Relation to the Great Lakes
Authors: Tinkler Keith J. , Pengelly James W. , Parkins William G. , Asselin Gary 
Published: October 2002

AbstractThe recessional history of Niagara Falls in the present Niagara Gorge during the postglacial period has been a focus of study throughout this century. Radiocarbon ages of clam shells suggest that Niagara Falls migrated very slowly around the narrowed gorge section at Niagara Glen from 10,500 to 5500 yr B.P., when upper Great Lakes water bypassed Lake Erie and flowed to the Ottawa River via the outlet at North Bay, Ontario. Prior to that interval, river discharge and recession rates were similar to those at present, and similar rates resumed after 5200 yr B.P. By about 4500 yr B.P., the present gorge had intersected a buried gorge of the pre-late Wisconsinan Niagara River (St. Davids Gorge). The sediment derived from the excavated buried valley fill may be present as a distinct marker horizon in the sediments in southwestern Lake Ontario.
Fire History and Tree Recruitment in an Uncut New England Forest
Authors: Mann Daniel H. , Engstrom F.Brett , Bubier Jill L. 
Published: October 2002

AbstractFire and forest histories in a hemlock-pine forest in Vermont have been reconstructed by dating fire scars and reconstructing the age distributions of living and dead trees. The ages of living red pines, white pines, and hemlocks show that most of the present forest germinated after a series of spatially overlapping fires between A.D. 1790 and 1850. The ages of cross-dated, dead red pines indicate that this was the third major recruitment interval for pines in this forest since ca. A.D. 1450. We interpret the fire scar and tree age data as recording ca. 50-yr intervals of increased fire frequency recurring every 100-200 yr in response to accumulating fuel loads that coincide with summer drought. The historical records of fires and tree ages, together with the present fuel load, suggest that the next interval of stand-regenerating fires is now overdue. Our success in cross-dating the remnants of dead red pines as old as the 15th century A.D. holds promise for extending reconstructions of fire, forest, and climate history in other parts of this tree's range.