bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fashion and phases of late Pleistocene aggradation and incision in the Alaknanda River Valley, western Himalaya, India
Authors: Srivastava Pradeep , Tripathi Jayant K. , Islam R. , Jaiswal Manoj K. 
Published: June 2008

AbstractWe study the aggradation and incision of the Alaknanda River Valley during the late Pleistocene and Holocene. The morphostratigraphy in the river valley at Deoprayag shows the active riverbed, a cut terrace, and a fill terrace. The sedimentary fabric of the fill terrace comprises four lithofacies representing 1) riverbed accretion, 2) locally derived debris fan, 3) the deposits of waning floods and 4) palaeoflood records. The sedimentation style, coupled with geochemical analysis and Optically Stimulated Luminescence (OSL) dating, indicate that this terrace formed in a drier climate and the river valley aggraded in two phases during 21–18 ka and 13–9 ka. During these periods, sediment supply was relatively higher. Incision began after 10 ka in response to a strengthened monsoon and aided by increase of the tectonic gradient. The cut terrace formed at ~ 5 ka during a phase of stable climate and tectonic quiescence. The palaeoflood records suggest wetter climate 200–300 yr ago when the floods originated in the upper catchment of the Higher Himalaya and in the relatively drier climate ~ 1.2 ka when locally derived sediments from the Lesser Himalaya dominated flood deposits. Maximum and minimum limits of bedrock incision rate at Deoprayag are 2.3 mm/a and 1.4 mm/a.
Involvement of the MADS-Box GeneZMM4in Floral Induction and Inflorescence Development in Maize
Authors: Danilevskaya Olga N. , Meng Xin , Selinger David A. , Deschamps Stéphane , Hermon Pedro , Vansant Gordon , Gupta Rajeev , Ananiev Evgueni V. , Muszynski Michael G. 
Published: June 2008

AbstractThe switch from vegetative to reproductive growth is marked by the termination of vegetative development and the adoption of floral identity by the shoot apical meristem (SAM). This process is called the floral transition. To elucidate the molecular determinants involved in this process, we performed genome-wide RNA expression profiling on maize (Zea mays) shoot apices at vegetative and early reproductive stages using massively parallel signature sequencing technology. Profiling revealed significant up-regulation of two maize MADS-box (ZMM) genes, ZMM4 and ZMM15, after the floral transition. ZMM4 and ZMM15 map to duplicated regions on chromosomes 1 and 5 and are linked to neighboring MADS-box genes ZMM24 and ZMM31, respectively. This gene order is syntenic with the vernalization1 locus responsible for floral induction in winter wheat (Triticum monococcum) and similar loci in other cereals. Analyses of temporal and spatial expression patterns indicated that the duplicated pairs ZMM4-ZMM24 and ZMM15-ZMM31 are coordinately activated after the floral transition in early developing inflorescences. More detailed analyses revealed ZMM4 expression initiates in leaf primordia of vegetative shoot apices and later increases within elongating meristems acquiring inflorescence identity. Expression analysis in late flowering mutants positioned all four genes downstream of the floral activators indeterminate1 (id1) and delayed flowering1 (dlf1). Overexpression of ZMM4 leads to early flowering in transgenic maize and suppresses the late flowering phenotype of both the id1 and dlf1 mutations. Our results suggest ZMM4 may play roles in both floral induction and inflorescence development.
The Transcription Factor VvMYB5b Contributes to the Regulation of Anthocyanin and Proanthocyanidin Biosynthesis in Developing Grape Berries
Authors: Deluc Laurent , Bogs Jochen , Walker Amanda R. , Ferrier Thilia , Decendit Alain , Merillon Jean-Michel , Robinson Simon P. , Barrieu François 
Published: June 2008

AbstractAmong the dramatic changes occurring during grape berry (Vitis vinifera) development, those affecting the flavonoid pathway have provoked a number of investigations in the last 10 years. In addition to producing several compounds involved in the protection of the berry and the dissemination of the seeds, final products of this pathway also play a critical role in berry and wine quality. In this article, we describe the cloning and functional characterization of VvMYB5b, a cDNA isolated from a grape berry (V. vinifera ‘Cabernet Sauvignon’) library. VvMYB5b encodes a protein belonging to the R2R3-MYB family of transcription factors and displays significant similarity with VvMYB5a, another MYB factor recently shown to regulate flavonoid synthesis in grapevine. The ability of VvMYB5a and VvMYB5b to activate the grapevine promoters of several structural genes of the flavonoid pathway was confirmed by transient expression of the corresponding cDNAs in grape cells. Overexpression of VvMYB5b in tobacco (Nicotiana tabacum) leads to an up-regulation of genes encoding enzymes of the flavonoid pathway and results in the accumulation of anthocyanin- and proanthocyanidin-derived compounds. The ability of VvMYB5b to regulate particularly the anthocyanin and the proanthocyanidin pathways is discussed in relation to other recently characterized MYB transcription factors in grapevine. Taken together, data presented in this article give insight into the transcriptional mechanisms associated with the regulation of the flavonoid pathway throughout grape berry development.
A Class I ADP-Ribosylation Factor GTPase-Activating Protein Is Critical for Maintaining Directional Root Hair Growth in Arabidopsis
Authors: Yoo Cheol-Min , Wen Jiangqi , Motes Christy M. , Sparks J. Alan , Blancaflor Elison B. 
Published: June 2008

Abstract
Membrane trafficking and cytoskeletal dynamics are important cellular processes that drive tip growth in root hairs. These processes interact with a multitude of signaling pathways that allow for the efficient transfer of information to specify the direction in which tip growth occurs. Here, we show that AGD1, a class I ADP ribosylation factor GTPase-activating protein, is important for maintaining straight growth in Arabidopsis (Arabidopsis thaliana) root hairs, since mutations in the AGD1 gene resulted in wavy root hair growth. Live cell imaging of growing agd1 root hairs revealed bundles of endoplasmic microtubules and actin filaments extending into the extreme tip. The wavy phenotype and pattern of cytoskeletal distribution in root hairs of agd1 partially resembled that of mutants in an armadillo repeat-containing kinesin (ARK1). Root hairs of double agd1 ark1 mutants were more severely deformed compared with single mutants. Organelle trafficking as revealed by a fluorescent Golgi marker was slightly inhibited, and Golgi stacks frequently protruded into the extreme root hair apex of agd1 mutants. Transient expression of green fluorescent protein-AGD1 in tobacco (Nicotiana tabacum) epidermal cells labeled punctate bodies that partially colocalized with the endocytic marker FM4-64, while ARK1-yellow fluorescent protein associated with microtubules. Brefeldin A rescued the phenotype of agd1, indicating that the altered activity of an AGD1-dependent ADP ribosylation factor contributes to the defective growth, organelle trafficking, and cytoskeletal organization of agd1 root hairs. We propose that AGD1, a regulator of membrane trafficking, and ARK1, a microtubule motor, are components of converging signaling pathways that affect cytoskeletal organization to specify growth orientation in Arabidopsis root hairs.
Cool C4 Photosynthesis: Pyruvate Pi Dikinase Expression and Activity Corresponds to the Exceptional Cold Tolerance of Carbon Assimilation inMiscanthus×giganteus
Authors: Wang Dafu , Portis Archie R. , Moose Stephen P. , Long Stephen P. 
Published: June 2008

AbstractThe bioenergy feedstock grass Miscanthus × giganteus is exceptional among C4 species for its high productivity in cold climates. It can maintain photosynthetically active leaves at temperatures 6°C below the minimum for maize (Zea mays), which allows it a longer growing season in cool climates. Understanding the basis for this difference between these two closely related plants may be critical in adapting maize to colder weather. When M. × giganteus and maize grown at 25°C were transferred to 14°C, light-saturated CO2 assimilation and quantum yield of photosystem II declined by 30% and 40%, respectively, in the first 48 h in these two species. The decline continued in maize but arrested and then recovered partially in M. × giganteus. Within 24 h of the temperature transition, the pyruvate phosphate dikinase (PPDK) protein content per leaf area transiently declined in M. × giganteus but then steadily increased, such that after 7 d the enzyme content was significantly higher than in leaves growing in 25°C. By contrast it declined throughout the chilling period in maize leaves. Rubisco levels remained constant in M. × giganteus but declined in maize. Consistent with increased PPDK protein content, the extractable PPDK activity per unit leaf area (V max ,ppdk) in cold-grown M. × giganteus leaves was higher than in warm-grown leaves, while V max,ppdk was lower in cold-grown than in warm-grown maize. The rate of light activation of PPDK was also slower in cold-grown maize than M. × giganteus. The energy of activation (E a) of extracted PPDK was lower in cold-grown than warm-grown M. × giganteus but not in maize. The specific activities and E a of purified recombinant PPDK from M. × giganteus and maize cloned into Escherichia coli were similar. The increase in PPDK protein in the M. × giganteus leaves corresponded to an increase in PPDK mRNA level. These results indicate that of the two enzymes known to limit C4 photosynthesis, increase of PPDK, not Rubisco content, corresponds to the recovery and maintenance of photosynthetic capacity. Functionally, increased enzyme concentration is shown to increase stability of M. × giganteus PPDK at low temperature. The results suggest that increases in either PPDK RNA transcription and/or the stability of this RNA are important for the increase in PPDK protein content and activity in M. × giganteus under chilling conditions relative to maize.
Characterization of Single and Double Inactivation Strains Reveals New Physiological Roles for Group 2 σ Factors in the Cyanobacterium Synechocystis sp. PCC 6803
Authors: Pollari Maija , Gunnelius Liisa , Tuominen Ilona , Ruotsalainen Virpi , Tyystjärvi Esa , Salminen Tiina , Tyystjärvi Taina 
Published: June 2008

Abstract
Cyanobacteria are eubacteria that perform oxygenic photosynthesis like plants. The initiation of transcription, mediated by the RNA polymerase holoenzyme, is the main determinant of gene regulation in eubacteria. The σ factor of the RNA polymerase holoenzyme is responsible for the recognition of a promoter sequence. In the cyanobacterium Synechocystis sp. PCC 6803, the primary σ factor, SigA, is essential for cell viability. The SigB, SigC, SigD, and SigE factors show significant sequence similarity with the SigA factor but are nonessential. In this study, we have used homology modeling to construct a three-dimensional model of Synechocystis RNA polymerase holoenzyme and all group 1 and 2 σ factors. According to the models, the overall three-dimensional structures of group 1 and 2 σ factors are similar, the SigB and SigD factors being the most similar ones. In addition, we have constructed a complete set of group 2 σ factor double inactivation strains, ΔsigBC, ΔsigBD, ΔsigBE, ΔsigCD, ΔsigCE, and ΔsigDE. All double mutants grow well under standard conditions, but differences are observed in stress conditions. The transition from lag phase to exponential growth is slow in the ΔsigBD strain, and all strains lacking the SigD factor were found to be sensitive to bright light. Furthermore, all group 2 σ factors were found to be involved in acclimation to salt- or sorbitol-induced osmotic stresses.
ArabidopsisPEROXIN11c-e, FISSION1b, and DYNAMIN-RELATED PROTEIN3A Cooperate in Cell Cycle–Associated Replication of Peroxisomes
Authors: Lingard Matthew J. , Gidda Satinder K. , Bingham Scott , Rothstein Steven J. , Mullen Robert T. , Trelease Richard N. 
Published: June 2008

AbstractAlthough participation of PEROXIN11 (PEX11), FISSION1 (FISl), and DYNAMIN-RELATED PROTEIN (DRP) has been well established during induced peroxisome proliferation in response to external stimuli, their roles in cell cycle–associated constitutive replication/duplication have not been fully explored. Herein, bimolecular fluorescence complementation experiments with Arabidopsis thaliana suspension cells revealed homooligomerization of all five PEX11 isoforms (PEX11a-e) and heterooligomerizations of all five PEX11 isoforms with FIS1b, but not FIS1a nor DRP3A. Intracellular protein targeting experiments demonstrated that FIS1b, but not FIS1a nor DRP3A, targeted to peroxisomes only when coexpressed with PEX11d or PEX11e. Simultaneous silencing of PEX11c-e or individual silencing of DRP3A, but not FIS1a nor FIS1b, resulted in ∼40% reductions in peroxisome number. During G2 in synchronized cell cultures, peroxisomes sequentially enlarged, elongated, and then doubled in number, which correlated with peaks in PEX11, FIS1, and DRP3A expression. Overall, these data support a model for the replication of preexisting peroxisomes wherein PEX11c, PEX11d, and PEX11e act cooperatively during G2 to promote peroxisome elongation and recruitment of FIS1b to the peroxisome membrane, where DRP3A stimulates fission of elongated peroxisomes into daughter peroxisomes, which are then distributed between daughter cells.
Light-Induced Phosphorylation and Degradation of the Negative Regulator PHYTOCHROME-INTERACTING FACTOR1 fromArabidopsisDepend upon Its Direct Physical Interactions with Photoactivated Phytochromes
Authors: Shen Hui , Zhu Ling , Castillon Alicia , Majee Manoj , Downie Bruce , Huq Enamul 
Published: June 2008

AbstractThe phytochrome (phy) family of photoreceptors regulates changes in gene expression in response to red/far-red light signals in part by physically interacting with constitutively nucleus-localized phy-interacting basic helix-loop-helix transcription factors (PIFs). Here, we show that PIF1, the member with the highest affinity for phys, is strongly sensitive to the quality and quantity of light. phyA plays a dominant role in regulating the degradation of PIF1 following initial light exposure, while phyB and phyD and possibly other phys also influence PIF1 degradation after prolonged illumination. PIF1 is rapidly phosphorylated and ubiquitinated under red and far-red light before being degraded with a half-life of ∼1 to 2 min under red light. Although PIF1 interacts with phyB through a conserved active phyB binding motif, it interacts with phyA through a novel active phyA binding motif. phy interaction is necessary but not sufficient for the light-induced phosphorylation and degradation of PIF1. Domain-mapping studies reveal that the phy interaction, light-induced degradation, and transcriptional activation domains are located at the N-terminal 150–amino acid region of PIF1. Unlike PIF3, PIF1 does not interact with the two halves of either phyA or phyB separately. Moreover, overexpression of a light-stable truncated form of PIF1 causes constitutively photomorphogenic phenotypes in the dark. Taken together, these data suggest that removal of the negative regulators (e.g., PIFs) by light-induced proteolytic degradation might be sufficient to promote photomorphogenesis.
Study on lubricant quality and its effect on engine component performance
Authors: Beşergil Bilsen , Sabih Özer M. , Eskici Mustafa , Atik Enver 
Published: June 2008

PurposeThis paper aims to determine the usage time of the test lubricant N0, prepared from base oils of Aliaga Plant, Izmir, in gasoline and diesel‐engines, and the investigations of high‐temperature oxidation, engine‐protective properties, and property changes of the lubricant in performance time.Design/methodology/approachPhysical and chemical properties of the lubricating oil were initially established, and the oil was then subjected to Petter W‐1 gasoline and Petter AV‐1 diesel test engines. Dismantling of the engine parts was followed by the examination of pistons, piston rings and bearings, and analysis of the lubricant was also undertaken. The engine performance test results and the quality control of the lubricating oil assessments were evaluated according to the International Engine Lubricant Specifications.FindingsThe lubricating oil, under sluggish experimental conditions, appears to meet a 40‐hour test in gasoline engines and a 120‐hour test in diesel engines with the specifications. This means that under usual working conditions the lubricants keep the engine protective properties in 7,000 km distance for gasoline run‐vehicles, and in 5,000 km distance for diesel run‐vehicles, after which change of the oil is required.Originality/valueThe paper provides information of value to those involved with lubrication and engine performance.
Comparative study of friction behaviour of alumina and zirconia ceramics against steel under water lubricated conditions
Authors: Paulo Davim J. , Santos Edgar , Pereira Catarina , Ferreira J.M.F. 
Published: June 2008

PurposeThe paper aims to study the friction behaviour of alumina and zirconia against steel DIN‐Ck45K under water lubricated conditions.Design/methodology/approachThe tests were performed with a contact stress of 3.5 MPa and a constant sliding velocity of 0.5 m/s for 5.35 km of sliding distance, using a pin‐on‐disk tribometer.FindingsThe friction coefficient and the energy dissipated in the contact were considered in this comparative study. The zirconia ceramic present less friction coefficient and contact temperature than alumina ceramic. The zirconia present about 70 per cent of the energy dissipated against when compared with the alumina. Abrasive scars of the surface ploughing were observed on every wear track for two pairs in contact.Research limitations/implicationsThis research used only one test condition.Originality/valueThe paper describes the tribological conditions used and a new methodology based on the energy dissipated in the contact is proposed.
Tribological performance of 2‐mercaptobenzothiazole derivatives as lubricating oil additives
Authors: Wu Hua , Zeng X.Q. , Ren T.H. 
Published: June 2008

PurposeThe paper's aim is to study tribological performances of two 2‐mercaptobenzothiazole derivatives which are ashless and lacking in phosphorous as lubricating oil additives in HVIW H150 base oils.Design/methodology/approachThe two 2‐mercaptobenzothiazole derivatives were synthesized; their tribological performances were evaluated with a four‐ball machine, and the worn surface was analyzed with a X‐ray photoelectron spectroscopy (XPS).FindingsThe two compounds possess good anti‐wear properties and excellent load‐carrying capacity. According to the XPS results, the additive reacted with counter‐face metal and generated a sulphur‐containing inorganic film consisting of FeS, FeS2 and FeSO4, and a complex N‐containing resin polymer film.Research limitations/implicationsTheir antioxidant properties are not estimated, and their anti‐wear action mechanism need to be further explored.Practical implicationsTwo useful ashless AW lubricating oil additives were synthesized, and may be has potential as gas engine lubricating oil additives.Originality/valueThis paper provides a study of some N, S‐containing heterocyclic compounds as lubricating oil additives.
Tribological behavior of dual and triple particle size SiC reinforced Al‐MMCs: a comparative study
Authors: Maleque Abdul , Karim Rezaul 
Published: June 2008

PurposeThe aim is to study the tribological behavior of dual particle size (DPS) and triple particle size (TPS) SiC reinforced aluminum alloy‐based metal matrix composites – MMCs (Al/SiCp MMC).Design/methodology/approachAl‐MMCs with DPS and TPS of SiC were prepared using 20 wt% SiC and developed using stir‐casting process. The TPS composite consist of three different sizes of SiC and DPS composite consist of two different sizes of SiC. The tribological test was carried out using a pin‐on‐disc type tribo‐test machine under dry sliding condition.FindingsThe TPS composite exhibited better wear resistance properties compared to DPS composite. It is anticipated that when a composite is integrated with small, intermediate and large SiC particle sizes (which is known as TPS) within the same composite could be an effective method of optimizing the wear resistance properties of the developed material.Practical implicationsThis study provides a way to enhance the tribological behavior of automotive tribo‐components such as brake rotor, piston, cylinder, etc.Originality/valueThis investigation compares the tribological behavior of DPS and TPS SiC reinforced aluminum MMCs.
Friction and wear behaviours of some industrial polyamides against different polymer counterparts under dry conditions
Authors: Unal H. , Findik F. 
Published: June 2008

PurposeThe present study aims to find out the best polymer/polymer pair in electrical insulating applications. Moreover, the effects of different polymer counterpart and applied load on the friction and wear behaviour of PA 46 + 30%GFR and unfilled PA 66 thermoplastic polymers are to be studied.Design/methodology/approachFriction and wear tests vs PA 46 + 30%GFR and PPS + 30%GFR polymer composites were carried out on a pin‐on‐disc arrangement and at a dry sliding conditions. Tribological tests were performed at room temperature under 20, 40 and 60 N loads and at 0.5 m/s sliding speed.FindingsThe results showed that, the coefficient of friction decreases with the increasing of load (up to 40 N) for PA 46 + 30%GFR composite and polyamide (PA) 66 polymer used in this study. However, above 40 N applied load the coefficient of friction increases. The specific wear rate for PA 46 + 30%GFR and PA 66 against PPS + 30%GFR polymer composite counterpart are about in the order of 10−13 m2/N while the specific wear rate for PA 46 + 30%GFR and PA 66 against PA 46 + 30%GFR polymer composite counterpart are in the order of 10−14 m2/N. For PA 46 + 30%GFR composite and unfilled PA 66 polymers tested the specific wear rate values increased with the increment of load. The highest specific wear rate is for unfilled PA 66 against PPS + 30%GFR with a value of 2.81 × 10−13 m2/N followed by PA 66 against PA 46 + 30%GFR with a value of 2.26 × 10−13 m2/N. The lowest wear rate is PA 46 + 30%GFR polymer composite against PA 46 + 30%GFR polymer composite counterpart with a value of 3.19 × 10−14 m2/N. The average specific wear rates for unfilled PA 66 against PA 46 + 30%GFR is 80 times higher than PA 46 + 30%GFR wear rate while specific wear rates for unfilled PA 66 against PPS + 30%GFR is 100 times higher than that of PA 46 + 30%GFR wear rate. From point view of tribological performance, PA 46 + 30%GFR is a more suitable engineering thermoplastic composite materials for electrical contact breaker applications.Research limitations/implicationsIn the present work, tribological tests were performed only at room temperature under three different loads and a sliding speed. This is the limitation of the work.Practical implicationsThis work is easily used for industrial polyamides to check their tribological behaviours.Originality/valueThis is an original and experimental study and it will be useful both for academicians and for industrial sides.