bluuebunny/crossref_metadata_2025 huggingface dataset:
Parallel interference cancellation employing RAKE receiver with selection diversity for multiuser asynchronous DS/CDMA detectors in multipath Rayleigh fading channels
Authors: Al‐Hussaini Emad K. , Mourad Hebatallah M. , Gohary Ramy H.
Published: October 2002

In this paper, we propose and analyse parallel CCI multistage cancellation by combining RAKE and selection diversity. In order to account for channel variations, adaptive implementation of decision thresholds at the RAKE output is suggested. It is shown to provide significant improvement over either hard or soft decision techniques especially in the near‐far situation. Investigation of the system robustness to imperfect channel parameter estimation is also presented. The communication channel is modelled as slowly varying Rayleigh fading discrete multipath channel. Copyright © 2002 John Wiley & Sons, Ltd.
Investigation of the influence of particle size on the quantitative analysis of glasses by energy‐dispersive micro x‐ray fluorescence spectrometry
Authors: Roedel T. C. , Bronk H. , Haschke M.
Published: October 2002

Micro x‐ray fluorescence analyses were undertaken on individual glass particles of different compositions for selected particle sizes between 50 µm and ≥1 mm. These experiments revealed a complex behaviour in the fluorescence spectra; this behaviour is influenced by the glass matrix, topology, particle volume, energy range and polycapillary properties and cannot be corrected by simple approaches. Net fluorescence intensities and reproducibility measured with two different polycapillaries (40 and 60 µm) were evaluated for six element lines between 1 and 10 keV and compared with the same standard glasses provided as ideal specimens (i.e. with flat, polished surface and of ‘infinite’ thickness). A standardless quantification using the fundamental parameter model gave a reasonable accuracy for particle sizes ≥1 mm (ca 15% relative standard deviations for the main elements) without further sample preparation. The feasibility of principal components analysis for a fast identification of compositional types using the measurement data of individual particles was demonstrated. Copyright © 2002 John Wiley & Sons, Ltd.
Sequential leaching of trace elements in fine‐particle aerosol samples on Teflon filters
Authors: Moloi K. , Viksna A. , Selin Lindgren E. , Standzenieks P.
Published: October 2002

The mobility of different elements in the environment is an important factor to consider when assessing the risk of pollution. Airborne particles of micrometre or smaller sizes are known to be transported over vast distances, and may therefore affect regions far away from their sources. As a complement to the more traditional element analysis of fine‐particle aerosols, the possibility of obtaining information on the element contents in particle fractions of different environmental mobilities and/or character was explored. A four‐stage sequential leaching procedure was tested and applied to establish the distribution of metals in four different fine‐particle fractions, namely (1) the fraction considered to be mobile in the environment, (2) the fraction bound to carbonates and oxides, (3) the fraction bound to organic matter, and (4) the fraction bound to silicates. Subtraction of energy‐dispersive x‐ray fluorescence (XRF) spectra was used to evaluate the element concentrations in the filters. For validation, total‐reflection XRF was used in a few cases for analysis of leachates. The methods were applied to airborne particles collected in two locations in Botswana. In both locations the K, Ca, Mn, Zn, Br and Pb compounds were found to occur extensively in the environmentally mobile fraction, whereas Ti and Fe were found to dominate in the silicate fraction. Copyright © 2002 John Wiley & Sons, Ltd.
Fit values of M subshell fluorescence yields and Coster–Kronig transitions for elements with 20 ≤ Z ≤ 90
Authors: Söǧüt Ö. , Büyükkasap E. , Küçükönder A. , Ertuǧrul M. , Doǧan O. , Erdoǧan H. , Şimşek Ö.
Published: October 2002

Most probable values of Mi subshell fluorescence yields (i = 1–5) and Coster–Kronig (CK) transition Sij probabilities (S12, S13, S14, S15, S23, S24, S35, S34, S35 and f45) were determined by using least squares fitted to obtain the polynomials, which were plotted by using McGuire's values, representing them as a function of atomic number. Values of Mi subshell fluorescence yields (i = 1–5) and ϖM and CK transition Sij probabilities as above are presented in tables. Copyright © 2002 John Wiley & Sons, Ltd.
Saccharomyces cerevisiae Big1p, a putative endoplasmic reticulum membrane protein required for normal levels of cell wall β‐1,6‐glucan
Authors: Azuma Masayuki , Levinson Joshua N. , Pagé Nicolas , Bussey Howard
Published: October 2002

Deletion of Saccharomyces cerevisiae BIG1 causes an approximately 95% reduction in cell wall β‐1,6‐glucan, an essential polymer involved in the cell wall attachment of many surface mannoproteins. The big1 deletion mutant grows very slowly, but growth can be enhanced if cells are given osmotic support. We have begun a cell biological and genetic analysis of its product. We demonstrate, using a Big1p–GFP fusion construct, that Big1p is an N‐glycosylated integral membrane protein with a Type I topology that is located in the endoplasmic reticulum (ER). Some phenotypes of a big1Δ mutant resemble those of strains disrupted for KRE5, which encodes another ER protein affecting β‐l,6‐glucan levels to a similar extent. In a big1Δkre5Δ double mutant, both the growth and alkali‐soluble β‐l,6‐glucan levels were reduced as compared to either single mutant. Thus, while Big1p and Kre5p may have similar effects on β‐l,6‐glucan synthesis, these effects are at least partially distinct. Residual β‐l,6‐glucan levels in the big1Δkre5Δ double mutant indicate that these gene products are unlikely to be β‐l,6‐glucan synthase subunits, but rather may play some ancillary roles in β‐l,6‐glucan synthase assembly or function, or in modifying proteins for attachment of β‐l,6‐glucan. Copyright © 2002 John Wiley & Sons, Ltd.
Effect of dietary calcium and phosphorus vitamin D metabolites 25(OH)D and 1,25(OH)2D, and response to bPTH (1‐34) in blue duikers
Authors: Roeder Beverly L. , Varga Gabriella A. , Wideman Robert F. , Hollis Bruce W.
Published: October 2002

In a colony of blue duiker antelope (Cephalophus monticola bicolor) at Pennsylvania State University, many animals had reversed Ca:P ratios and acid‐base imbalance, and some developed urinary calculi. The purpose of this study was to investigate the relationship between age, dietary Ca, P, and the homeostatic mechanisms controlling their extracellular fluid levels. Sixteen males (1–5 years old) had serum and urine electrolytes and vitamin D metabolites evaluated before, during, and after bPTH (1‐34) intravenous infusion while consuming 1.38%Ca:0.66%P, and after consuming one of four experimental diets (Ca and P: 0.5:0.4%, 0.8:0.8%, 0.8:0.4%, 1.25:0.4%) for four months. Pretrial, all duikers responded similarly to bPTH. Post‐trial bPTH caused an increase in serum Ca and a decrease in P followed by a rebound in P in duikers consuming 0.4% P and either 0.5, 0.8, or 1.25% Ca, whereas the 0.8:0.8% (high P diet) caused a decline in serum Ca and no change in P, followed by an increase in serum P to higher levels than baseline. Vitamin D metabolites pretrial were similar between age groups and assigned treatment. Post‐trial 1,25(OH)2D was significantly lower in younger males consuming diets with %Ca > %P than in older males. 25(OH)D was similar between age groups. Ca intake inversely affected 25(OH)D (P < 0.002) and was directly related to 1,25(OH)2D. P intake inversely affected 1,25(OH)2D (P < 0.04) and was directly related to 25(OH)D. This suggests that blue duikers have a unique ruminant response to PTH that is related to vitamin D metabolism as influenced by the dietary level of Ca and P, and the age of the animal. This may indicate an age‐related impairment of 25(OH)D metabolism in young duikers, or a dependence on increased 1,25(OH)2D to maintain Ca and P homeostasis in older animals. Zoo Biol 21:171–183, 2002. © 2002 Wiley‐Liss, Inc.
Hurricane intensity changes associated with geomagnetic variation
Authors: Elsner James B. , Kavlakov S. P.
Published: October 2002

Recently some indications have appeared that several purely meteorological processes in the terrestrial atmosphere are dependent upon magnetosphere variations. To analyse the possible relationship with North Atlantic hurricane intensification, the authors examine geomagnetic data for ten days prior to all hurricanes over the last 50 years (1950–1999). A significant positive correlation between the averaged Kp index of global geomagnetic activity and hurricane intensity as measured by maximum sustained wind speed is identified for baroclinically‐initiated hurricanes. Results are consistent with a mechanism whereby ionization processes trigger glaciation at cloud top which leads to hurricane intensification through upper tropospheric latent heat release. Copyright © 2003 Royal Meteorological Society.
Binding of low mobility group proteins with DNA examined in homologous and heterologous systems by Gel retardation assay.
Authors: Wiland Eva , Siemieniako Barbara , Trzeciak Wieslaw H.
Published: October 2002

The interaction of low mobility group proteins (LMG), isolated from chromatin of pancreatic carcinoma cells (CAPAN‐2), with fragments of 5′‐flanking region of the antigen 17‐1A gene was studied by gel retardation assay. The LMG proteins, which formed complexes with DNA were extracted from the gels and identified by polyacrylamide gel electrophoresis under denaturing conditions. The proteins of Mw about 100, 60, 55 and 48 kDa, which formed specific complexes with fragments of 5′‐flanking region of the antigen 17‐1A gene, were identified.
Helical inclusions with nucleopore‐like characteristics in the cytoplasm of swiss 3T3 Cells: A preliminary communication.
Authors: Wheatley Denys N.
Published: October 2002

Helical inclusions have been observed at sites remote from the nucleus in the cytoplasm of Swiss 3T3 fibroblasts. Because of the interest shown in their unusual nucleopore complex‐like nature, this preliminary communication briefly reports their existence and describes their essential ultrastructural features. Although they could be found singly, most formed collections of up to about 30 inclusions in which different planes of section were represented. TS profiles with hexagonal packing showed apparently identical eight‐fold symmetry and dimensions to pores in the nuclear envelope of 3T3 cells. No membranes were associated with the inclusions, nor was there any suggestion of the strict vertical plate‐like stacking found in annulate lamellae (AL). Furthermore, the inclusions were undoubtedly helical, and in all probability composed of several strands.
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

Microtubules 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

The 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

The 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

The 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

Proton 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

In 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

Ultrastructural 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

Recombinant 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.
TWO‐DIMENSIONAL PROTEIN MAPS OF XENOPUS EGGS AND EMBRYOS AT DIFFERENT DEVELOPMENTAL STAGES
Authors: TEDESCHI GABRIELLA , BERNARDINI GIOVANNI , MORTARINO MICHELE , NEGRI ARMANDO , CECILIANI FABRIZIO , RONCHI SEVERINO
Published: October 2002

Protein expression during the early development of Xenopus has been followed by 2D‐polyacrylamide gel electrophoresis (PAGE). The analysis of two‐dimensional maps of eggs and embryos at different stages of development has allowed the separation of more than 2000 spots. Identification of numerous polypeptides was obtained in four different ways: (1) immuno‐blotting; (2) amino terminal sequence after blotting on to PVDF membranes; (3) comigration; and (4) assignment in comparison with proteins separated by 2D techniques on reference maps such as human liver, red blood cells, plasma and cerebrospinal fluid reported in the Swiss 2D‐PAGE Data Base. The maps presented in this report are a step toward the study of the protein expression in Xenopus eggs and embryos and may be a powerful working tool since Xenopus embryos are popular models for the study of development.
PROTEIN DOMAINS INVOLVED IN NUCLEAR TRANSPORT OF FOS
Authors: Campos M.A.S , Kroon E.G , Gentz R. , Ferreira P.C.P
Published: October 2002

The protein encoded by the proto‐oncogene c‐fos is constitutively nuclear in most cell types analyzed. It has a predicted molecular weight of about 55kDa. Proteins with a molecular weight above 40kDa cannot enter the nucleus passively. Our interest was to study which regions in the protein are involved in the nuclear transport. We prepared a series of deletions and point mutations of the protein and cloned the mutated genes into a eukaryotic expression vector. Cos‐1 cells were used to express the mutants transiently. Using indirect immunofluorescence we studied the subcellular localization, analyzing the percentage of cells containing the protein in the nucleus, the cytoplasm, or both locations. Our studies showed that the Fos protein contains several regions which can act independently to translocate the protein into the nucleus.
p53 DOES NOT CONTROL THE SPINDLE ASSEMBLY CELL CYCLE CHECKPOINT BUT MEDIATES G1 ARREST IN RESPONSE TO DISRUPTION OF MICROTUBULE SYSTEM
Authors: Sablina Anna A. , Agapova Larissa S. , Chumakov Peter M. , Kopnin Boris P.
Published: October 2002

p53 plays a critical role as a tumour‐suppressor in restricting the proliferation of damaged cells, thus preventing formation of genetically altered cell clones. Its inactivation leads, in particular, to accumulation of polyploid and aneuploid cells. To elucidate the role of p53 in control of chromosome number, we analysed its participation in the cell cycle checkpoints controlling: (1) spindle assembly; and (2) G1‐to‐S transitions in cells with disintegrated microtubule cytoskeleton. Treatment with 8–10ng/ml of colcemid causing no visible destruction of the spindle leads to arrest of metaphase‐to‐anaphase transition in both p53‐positive and p53‐negative murine fibroblasts, as well as in p53‐positive REF52 cells and their counterparts (where the p53 function was inactivated by transduction of dominant‐negative p53 fragment). Furthermore, p53‐positive and p53‐defective rodent and human cells showed no significant difference in kinetics of metaphase‐to‐interphase transitions in cultures treated with high colcemid doses preventing spindle formation. These data argue against the hypothesis that p53 is a key component of the spindle‐assembly checkpoint. However, p53 mediates activation of the G1 checkpoint in response to depolymerization of microtubules in interphase cells. Treatment of synchronized G0/G1 cells with colcemid causes arrest of G1‐to‐S transition. Inactivation of the p53 function by transduction of dominant‐negative p53 fragment abolishes the G1 checkpoint that prevents entry into S phase of cells with disrupted microtubules. Transduction of kinase‐defective dominant‐negative c‐raf mutant or application of PD 098059, a specific inhibitor of MEK1, also abrogates the G1 cell cycle arrest in cells with disintegrated microtubule system. It seems that Raf‐MAP‐kinase signalling pathways are responsible for p53 activation induced by depolymerization of microtubules.
ELEVATED LEVEL OF gas3 GENE EXPRESSION IS CORRELATED WITH G0 GROWTH ARREST IN HUMAN FIBROBLASTS
Authors: Karlsson Christina , Afrakhte Mozhgan , Westermark Bengt , Paulsson Ylva
Published: October 2002

The gas3/PMP22 gene product is a dual function protein, involved in both peripheral nerve myelination and cell proliferation. gas 3/PMP22 is highly expressed in myelinating Schwann cells and is required for normal PNS development. In addition, a more general function for gas3 is suggested by its expression in non‐neural tissues and upregulation by growth arrest in cultured rodent fibroblasts. In the present work, the expression of the gas3 gene has been studied in human fibroblasts. We have confirmed that gas3 mRNA is upregulated when cells are serum starved or grown to high cell density (G0 arrest). When quiescent cells were stimulated by serum or platelet‐derived growth factor‐BB (PDGF‐BB),gas3 mRNA was down regulated. In contrast, we found that the expression of gas3 mRNA was neither upregulated in senescent cells nor in cells arrested in G1 using Lovastatin. Thus, high expression of gas3 is not related to growth inhibition in general, but more probably to the G0 growth arrest state. Furthermore, we found that in two malignant fibrous histiocytoma cell lines, gas3 expression was lower than in normal fibroblasts, suggesting an altered regulation of thegas3 gene in transformed cells.
GTP‐BINDING PROTEINS Gsα, Giα, AND RAN IDENTIFIED IN MITOCHONDRIA OF HUMAN PLACENTA
Authors: Kuyznierewicz Ileana , Thomson Murray
Published: October 2002

GTP‐binding proteins (GTPases) have been detected in the mitochondria of human placenta. It has been proposed that porin interacts with GTPases in the mitochondrion to modulate contact site function, however, their identity and location is not known. In this study, we investigated the location of GTPases in mitochondria from term placentae as well as the expression of mitochondrial GTPases in mid‐term placentae. Mitochondria obtained from human term and mid‐term placentae were purified by sedimentation. Sub‐mitochondrial vesicles prepared from ruptured and sonicated mitochondria were separated by ultracentrifugation in sucrose density gradients. The location of membrane vesicles was determined using marker enzymes. Mitochondrial proteins were separated by SDS‐PAGE. Western blots were incubated in [α‐32P]‐GTP and detected using autoradiography or antibodies against known GTPases and porin followed by enhanced chemiluminescence. [α‐32P]‐GTP bound 24 and 28kDa proteins located in the outer membrane. The Gsαantibody detected 42.5, 53 and 67kDa proteins. The Giαantibody identified a 40.5kDa band in contact sites and the outer membrane, as well as 55 and 105kDa proteins in contact site vesicles. The Ran antibody detected a 28kDa protein, mainly in the outer membrane. Porin migrated at 30kDa. Giαand Ran were detected in mitochondria from both term and mid‐term placentae. The location of porin and GTPases leave open the possibility that these proteins interact in contact sites and may also be responding to extra‐mitochondrial signals. Ran and Giαare expressed by mid‐term in human placentae and may be necessary for placental functions at this stage of development. It will be important in future experiments to characterise the physiological functions of these GTP‐binding proteins in the mitochondria of human placenta.
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

In 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

We 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

The 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

The 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

The 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

A 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

A 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

Four 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

A 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

The 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

Fire 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.
Correlation of Late Pleistocene Glaciolacustrine and Marine Deposits by Means of Geomagnetic Secular Variation, with Examples from Northern New York and Southern Ontario
Authors: Pair Donald L. , Muller Ernest H. , Plumley Peter W.
Published: October 2002

The geomagnetic secular variation record retained by glaciolacustrine and marine sediments at nine sites in northern New York and southern Ontario provides a means for stratigraphic correlation of glacial deposits for the time period between about 12,600 to 9900 14C yr B.P. Measurement of the depositional remanent magnetism of sediments deposited in Glacial Lake Iroquois and the Champlain Sea has produced a geomagnetic secular variation curve that represents the time period immediately following deglaciation about 12,600 14 C yr B.P. The curve varies from about 358° to 344° declination and 51° to 61° inclination over approximately 180 valve years. Marine sediments of the Champlain Sea have preserved a record approximately 1500 yr long that varies from about 2° to 29° declination and 47° to 60° inclination. These combined glacial-paleomagnetic records may also correlate with those from glacial sequences beyond our study area. The shape and amplitude of the secular variation record in glaciolacustrine and marine sediments from the western Adirondack borderland show agreement with other glacial varve secular variation records and suggest possible correlations with secular variation curves from lake cores.
Numerical Modeling of the Late Weichselian Svalbard-Barents Sea Ice Sheet
Authors: Siegert Martin J. , Dowdeswell Julian A.
Published: October 2002

Previous reconstructions of the ice cover of the Svalbard-Barents Sea region during the late Weichselian have ranged from small ice masses on Svalbard to complete inundation of the Barents Shelf region by an ice sheet several kilometers thick. We have used a time-dependent finite-difference numerical model to undertake a new glaciological reconstruction for the Svalbard-Barents Sea Ice Sheet over the last 30,000 yr. The numerical model requires environmental forcing functions in the form of air temperature and precipitation and their behavior with respect to altitude, together with sea-level change and an iceberg calving relation. Ice buildup on Svalbard is calculated to have begun 28,000 yr ago, and maximum dimensions were reached by 20,000 yr ago, covering Svalbard and the northwestern Barents Sea with a center of mass (1.3 km thick) around eastern Svalbard. Decay was complete by about 10,000 yr ago. The margin of the modeled ice sheet at its maximum is in good agreement with observed sea-floor morphological features, but there are discrepancies in timing between the modeled ice sheet decay and (i) a dated meltwater spike in Fram Strait and (ii) the observed rebound curves for Svalbard. An inverse approach was used to predict ice sheet decay, and it was found that increasing the rate of iceberg calving within the model produces a deglaciation some 2000 yr earlier, which is compatible with these two independent datasets. The reconstruction is also compatible with geological evidence on the isostatic response of Bjørnøya, close to the southern limit of the ice sheet, and seismically observed deposits, interpreted to be ice. proximal facies, located in the northwestern Barents Sea. Our time-dependent model reconstructions of the Svalbard-Barents Sea Ice Sheet indicate ice cover over only the northwestern Barents Sea during the late Weichselian, but this does not preclude the presence of ice derived from Fennoscandia and the Kara Sea region elsewhere in the Barents Sea.
Do Greenland Ice Cores Reflect NW European Interglacial Climate Variations?
Authors: Larsen Eiliv , Sejrup Hans Petter , Johnsen Sigfus J. , Knudsen Karen Luise
Published: October 2002

The climatic evolution during the Eemian and the Holocene in western Europe is compared with the sea-surface conditions in the Norwegian Sea and with the oxygen-isotope-derived paleotemperature signal in the GRIP and Renland ice cores from Greenland. The records show a warm phase (ca. 3000 yr long) early in the Eemian (substage 5e). This suggests that the Greenland ice sheet, in general, recorded the climate in the region during this time. Rapid fluctuations during late stage 6 and late substage 5e in the GRIP ice core apparently are not recorded in the climatic proxies from western Europe and the Norwegian Sea. This may be due to low resolution in the terrestrial and marine records and/or long response time of the biotic changes. The early Holocene climatic optimum recorded in the terrestrial and marine records in the Norwegian Sea-NW European region is not found in the Summit (GRIP and GISP2) ice cores. However, this warm phase is recorded in the Renland ice core. Due to the proximity of Renland to the Norwegian Sea, this area is probably more influenced by changes in polar front positions which may partly explain this discrepancy. A reduction in the elevation at Summit during the Holocene may, however, be just as important. The high-amplitude shifts during substage 5e in the GRIP core could be due to Atlantic water oscillating closer to, and also reaching, the coast of East Greenland. During the Holocene, Atlantic water was generally located farther east in the Norwegian Sea than during the Eemian.