bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sedimentology of Quaternary perched springline and paludal tufas: criteria for recognition, with examples from Guadalajara Province, Spain
Authors: Pedley Martyn , Martín Juan Antonio González , Delgado Salvador Ordóñez , García Del Cura MªÁngeles 
Published: March 2003

AbstractOutcrop‐scale geometries and bed relationships of ambient temperature freshwater carbonates are poorly understood because many described tufas have been dismantled by erosion and present only part of a particular depositional model. At the field scale, four end‐member models encompass the tufa continuum: (1) perched springline; (2) paludal; (3) fluvial; and (4) lacustrine tufas. Individual bed types can occur with variable dominance within several of these models, but one or more beds are characteristically dominant only within a single tufa model, so it can be differentiated from relatively isolated outcrop fragments. Two models (perched springline tufas and paludal tufas) are known in outline only in the literature despite being present within the Quaternary deposits of most karstic regions. Perched springline tufas generally form lobate, fan‐shaped mound morphologies on hillslopes and develop from single or multiple spring resurgences. Mature deposits show a subhorizontal top and a steep face on the downflow side. The steep outer zones of tufa mounds may be developed into cascades with moss curtains or can be dominated by shallow rimstone pools according to face angle. Tufa deposits lying downslope of the mounds are usually detrital in nature, especially if some dismantling of the mound has occurred. The relatively thin subhorizontal lobe‐top deposits commonly contain organic‐rich deposits. Paludal tufas develop predominantly in waterlogged valley bottom situations, where line‐sourced waters emerge from valley side and bottom aquifers. Lime mud precipitation predominates in these sites. Mud is deposited as subhorizontal laminites that thin towards the valley axis and downstream of resurgences. Tufa spring‐mounds may form where lesser volumes of water are involved. Individual tussocks (phytoherm cushions) of grasses and rushes are the most diagnostic feature of the model, but sapropels and peats may be intercalated. Diagenesis in both models is rapid. Lithification of individual beds is virtually instantaneous and always occurs before the decay of the associated living vegetation. The resulting highly porous and permeable fabrics remain fresh in Holocene tufas, but aggrading neomorphism and partial spar infill of vegetation moulds is common in older deposits. Dissolution in many perched springline tufas is small scale. Many large cavities are primary, but with later coatings of speleothems. Early removal of organics from paludal tufas is responsible for autobrecciation and differential compaction.
Phylogeny of Eulophidae (Hymenoptera: Chalcidoidea), with a reclassification of Eulophinae and the recognition that Elasmidae are derived eulophids
Authors: Gauthier N. , Lasalle J. , Quicke D. L. J. , Godfray H. C. J. 
Published: March 2003

SummaryEulophidae is a large and biologically varied family of parasitoid wasps, traditionally split into four subfamilies; Elasmidae is a uniform (single genus) and morphologically distinct family of wasps that are thought to be related to Eulophidae. The D2 region of the 28S rDNA gene (≈ 560 bp) of eighty‐seven species of eulophid, three species of elasmid and sixteen outgroup species in five families was sequenced. Cladograms were constructed, and the results compared with conclusions drawn from morphological studies. The gene was most informative at the level of subfamily and tribe. The monophyly of both Eulophinae and Tetrastichinae is supported; that of Entedoninae and Euderinae is less clear. Results indicate that Eulophinae is a derived group within Eulophidae, rather than an ancestral group as previously thought, and thatElasmus, the sole genus of Elasmidae, belongs within this subfamily. The tribes of Eulophinae are reassessed and only three accepted: Eulophini (including Euplectrini and Elachertini), Elasmini and Cirrospilini LaSalle trib.n. for Bouček's Ophelimini withOphelimusandAustralsecodesexcluded. Three small Australian tribes, Anselmellini, Ophelimini and Platytetracampini, are removed from Eulophinae and Entedoninae, respectively, but their exact relationships and subfamily status cannot as yet be decided. Another tribe, Keryini, known from a single Australian genus, is excluded from both Eulophinae and Eulophidae.
Neogene kinematics of the Giudicarie fault (Central‐Eastern Alps, Italy): new apatite fission‐track data
Authors: Martin S. , Bigazzi G. , Zattin M. , Viola G. , Balestrieri M.L. 
Published: March 2003

The Neogene kinematics of the Giudicarie fault (part of Periadriatic lineament, NE Italy) have been re‐examined using apatite fission‐track analysis. Twenty samples were collected along two geological sections; the first one crossing the Tertiary Corno Alto pluton (Adamello batholith) and the Variscan basement (Southalpine domain) adjacent to the South Giudicarie fault, the second one close to the North Giudicarie fault, in the Variscan basement of the Tonale nappe (Austroalpine system). Samples from the southern section show short tracks and ages between 14.7±1.2 Myr and 22.5±2.2 Myr along 1570 m of the profile; samples from the northern profile present long tracks and ages between 11.3±1.3 Myr and 14.7±3.4 Myr along 1225 m of the vertical profile. In the former, the presence of short tracks might indicate either a long permanence of the rocks in the apatite partial annealing zone, or a more complex thermal history; in the latter case we are dealing with rocks which experienced more rapid cooling. The two differing segments of the Giudicarie fault can be explained either as two completely independent tectonic features or, more likely, by hypothesizing a single fault active in its southern and northern parts at different times. Fission track data support a first exhumation of this single fault c. 15 Ma along the North Giudicarie, with a final exhumation towards the south, in the Adamello area, at c. 8–10 Ma (Mid Tortonian). This age fits with the so‐called ‘Giudicarie’ phase, during which σ1 in the stress field was orientated N280–290°.
Dolomites in the Tazekka Pb–Zn district, eastern Morocco: polyphase origin from hydrothermal fluids
Authors: Auajjar J. , Boulègue J. 
Published: March 2003

Many different types of water and processes have been proposed for the formation of dolomites. The three phases of hydrothermal dolomites in the Middle Atlas Causse were investigated to elucidate their formation processes. The first two of these are associated with sphalerite and galena in stratiform and open space‐filling deposits. These formed early in the history of the deposition of the Pb–Zn mineralization and commonly reveal a paragenetic overlap. A later phase, post‐dating Pb–Zn mineralization, is reflected in saddle dolomite.All three phases show a decrease in δ18O and δ13C values passing from sterile (unmineralized) to mineralized rocks, and isotopic signatures are independent of the carrier facies. However, early‐formed dolomites can be separated into two distinct groups on the basis of δ18O values. Type 1 dolomites host stratiform ore deposits, whereas type 2 dolomites host an open space‐filling ore‐body. Later saddle dolomites are more depleted in 18O than either of these.The early hydrothermal and saddle dolomites precipitated from similar fluids during three distinct events, but formed by two mechanisms: replacement (hydrothermal dolomite) and cement precipitation (saddle dolomite). They show different isotopic signatures and apparently formed at different temperatures. Field data, petrographic and stable isotope results suggest a continuum of replacement, during the Carixian for the early hydrothermal dolomite 1, and during the Toarcian for early hydrothermal dolomite 2, followed by a cement precipitation phase for saddle dolomite.
Identification and map position of YAC clones comprising one‐third of the Arabidopsis genome.
Authors: Hwang I , Kohchi T , Hauge BM , Goodman HM , Schmidt R , Cnops G , Dean C , Gibson S , Iba K , Lemieux B 
Published: March 2003

SummaryYAC clones corresponding to 125 Arabidopsis thaliana RFLP markers have been identified. At least one YAC clone has been isolated for each of the RFLP markers tested. Based on CHEF gel analysis of 196 clones, the mean insert size of the available Arabidopsis YAC libraries is approximately 160 kb. The YACs of known genetic map location encompass about 30% of the Arabidopsis genome. The results presented here represent a first step towards assembly of an overlapping YAC library of the A. thaliana genome.
T‐DNA as a gene tag
Authors: Richard Walden , Hayashi Hiroaki , Schell Jeff 
Published: March 2003

SummaryThe characteristics of Agrobacterium‐mediated plant transformation are such that the T‐DNA can be used as an insertional mutagen and, by extension, a gene tag. An increasing number of mutants have been obtained as a result of T‐DNA insertion and the versatility of this experimental system can be exploited further to tag sequences of DNA which control gene expression. While the isolation of specific mutations by T‐DNA tagging in the past has been fortuitous, T‐DNA‐based vectors have the potential to generate transgenic plants with specific, selectable mutations.
Expression pattern of a tobacco lipid transfer protein gene within the shoot apex
Authors: Fleming Andrew J. , Mandel Therese , Hofmann Sylvia , Sterk Peter , de Vries Sacco C. , Kuhlemeier Cris 
Published: March 2003

SummaryA genomic clone coding for a putative lipid transfer protein was isolated from Nicotiana tabacum. The gene is expressed in all aerial organs of the tobacco plant, with expression being highest in the upper part of the plant and declining towards the base (i.e. with increasing age). In the shoot apex transcript levels are highest in the LI layer, lower in the underlying cell layers, and are again higher in the submeristem region. This pattern is markedly different from those previously described for genes expressed within the shoot apex.
The methylation patterns of chromosomal integration regions influence gene activity of transferred DNA in Petunia hybrida
Authors: Pröls F. , Meyer P. 
Published: March 2003

SummaryThe regions of integration of a transferred DNA‐fragment from three transgenic Petunia hybrida plants were analysed for their influence on the expression of the foreign DNA. Each of the three transformants, lines 16, 17 and 24, contained a fragment of a plasmid on which two genes were located, an npt‐II gene which renders the plants resistant to kanamycin and the A1 gene from Zea mays, a visible marker gene that leads to the production of a brick red anthocyanin pigment in the flowers. Inactivation of both genes in line 16 is associated with integration into a region of highly repetitive DNA, while the integration sites of the other two lines were essentially unique. The integration regions of lines 17 and 24, both of which show expression of the foreign genes at characteristically different intensities, showed a distinct methylation pattern that was stably conserved for these regions in both trangenic and wild‐type plants. The characteristic methylation pattern of the two integration regions was also imposed on the border region of the integrated fragments and might thus be responsible for the differences in the intensity of gene expression observed among the two lines.
Four distinct nuclear proteins recognize in vitro the proximal promoter of the bean seed storage protein β‐phaseolin gene conferring spatial and temporal control
Authors: Kawagoe Yasushi , Murai Norimoto 
Published: March 2003

SummaryA proximal promoter (–422/–13) of the bean seed storage protein β‐phaseolin gene contains cis‐regulatory elements conferring spatial and temporal gene regulation. To correlate trans‐acting elements with these cis‐elements, we performed gel mobility shift and exonuclease III protection assays using bean seed nuclear proteins, and identified target sequences of four DNA‐binding proteins associated with this promoter. Three CANNTG motifs, CACGTG (–248/–243), CACCTG (–163/–158), and CATATG (–100/–95), were determined as target sequences of the same DNA‐binding protein designated CAN. Competition assays using oligonucleotides containing the wildtype or mutated CANNTG motif indicated that the CANNTG motif appears to be a preferred target sequence for CAN binding. Competition assays also demonstrated that DNA‐binding protein AG‐1 binds to AAAAAG(A/G)CAA (–356/–347, –191/–182), CA‐1 binds to two CA‐rich sequences (–201/–192, –175/–160), and that a TATA‐box binding protein binds to either TATATAA (–43/–37) or TATAAA (–32/–27) or both. Based on these and other results, it is proposed that CACGTG motif (–248/–243) is a major cis‐acting regulatory element conferring spatial and temporal control of the β‐phaseolin gene.
Expression of myb‐related genes in the moss, Physcomitrella patens
Authors: Leech Mark J. , Kammerer Wolfgang , Cove David J. , Martin Cathie , Wang Trevor L. 
Published: March 2003

SummaryThree cDNA clones encoding proteins containing a myb‐related DNA binding domain have been isolated from a cDNA library prepared from protonemal tissue of the moss, Physcomitrella patens. The three cDNA clones between them encode two different classes of myb‐like proteins, termed Pp1 and Pp2, that, outside of the myb domain, show no regions of significant homology. Acidic domains, capable of forming alpha‐helical structures, are present in the carboxy‐termini of the derived amino acid sequences from both Pp1 and Pp2 cDNAs suggesting that, like other myb genes, these proteins probably function as transcriptional activators. In contast to other plants, where extensive myb‐related gene families are present in the genome, a relatively small family is present in P. patens. Analyses of transcript levels during development of P. patens showed that maximum levels of transcription of the two genes occurred in young wild‐type protonemal tissue that correlated with the time of maximum mitotic index. A decline in the expression of both genes occurs with increasing age of the wild‐type tissue. Aberrant levels of expression of the two genes were observed in developmental mutants of P. patens which, as well as carrying specific morphological mutations, have greatly retarded protonemal growth rates. Transformation of wild‐type P. patens with antisense constructs derived from Pp1 and Pp2 cDNA clones led to a dramatically reduced frequency of transformants when the expression of the reporter gene within the constructs was selected. Taken together, the data strongly suggest that expression of Pp1 and Pp2 is essential for cell growth during normal gametophytic development of P. patens.
Promoter and leader regions involved in the expression of the Arabidopsis ferredoxin A gene
Authors: Caspar Timothy , Quail Peter H. 
Published: March 2003

SummaryFerredoxin is a nuclear‐encoded protein that is involved in a variety of electron transfer reactions in both photosynthetic and non‐photosynthetic plastids. We show here that the expression of the ferredoxin A gene (FedA) in Arabidopsis thaliana is light‐regulated, with its mRNA level increased 4.5‐fold by transfer of dark‐grown seedlings to white light for 3 h. A portion of this light regulation is mediated by phytochrome through a very low fluence type of response. In addition, it is likely that another photoreceptor(s) is also involved. The FedA promoter confers a light‐ and tissue‐regulated expression pattern when fused to the β‐glucuronidase (GUS) and luciferase reporter genes, indicating that the gene is transcriptionally regulated. No evidence of cis‐acting light‐regulatory elements within the 5′ untranslated leader region of the gene was detected. Nevertheless, elements within this leader are required for full activity since its deletion reduces expression both in the light and dark by 25‐fold. This region includes a sequence, ACAAAA, which is also present in the 5′ untranslated leader of the other three ferredoxin leaders that have been sequenced and in the leaders of 31 other plant genes or about 8% of all plant genes in the GenBank database. In addition to mediating light regulation, the FedA promoter also directs GUS expression in aerial tissues at 70‐fold higher levels than in roots. GUS activity staining in aerial tissues is observed in both photosynthetic and non‐photosynthetic cells. These data indicate that the FedA promoter also carries the information for expression of this gene in a highly tissue‐ and cell‐specific manner.
Characterization of two cDNAs that encode MAP kinase homologues in Arabidopsis thaliana and analysis of the possible role of auxin in activating such kinase activities in cultured cells
Authors: Mizoguchi Tsuyoshi , Gotoh Yukiko , Nishida Eisuke , Yamaguchi‐Shinozaki Kazuko , Hayashida Nobuaki , Iwasaki Toshisuke , Kamada Hiroshi , Shinozaki Kazuo 
Published: March 2003

SummaryTwo cDNA clones, cATMPK1 and CATMPK2, encoding MAP kinases (mitogen‐activated protein kinases) have been cloned from Arabidopsis thaliana and their nucleotide sequences have been determined. Putative proteins encoded by ATMPK1 and ATMPK2 genes, designated ATMPK1 and ATMPK2, contain 370 and 376 amino acid residues, respectively, and are 88.7% identical at the amino acid sequence level. ATMPK1 and ATMPK2 exhibit significant similarity to rat ERK2 (49%) and Xenopus MAP kinase (50%). The amino acid residues corresponding to the sites of phosphorylation (Thr‐Glu‐Tyr) that are involved in the activation of MAP kinases are conserved in ATMPK1 and ATMPK2. Northern blot analysis indicates that the ATMPK1 and ATMPK2 mRNAs are significantly present in all the organs except seeds. Genomic Southern blot analysis suggests that there are a few additional genes that are related to ATMPK1 and ATMPK2 in the Arabidopsis genome. Purified Xenopus MAP kinase kinase (MAPK kinase) phosphorylates ATMPK1 and ATMPK2 proteins that have been expressed in Escherichia coli, activating these enzymes. A rapid and transient activation of 46‐kDa protein kinase activity that phosphorylated myelin basic protein (MBP) was detected when auxinstarved tobacco BY‐2 cells were treated with synthetic auxin, 2,4‐dichlorophenoxyacetic acid (2,4‐D). Protein kinase activities which phosphorylated the recombinant ATMPK2 protein also increased rapidly after auxin treatment in the auxin‐starved BY‐2 cells. These results suggest that auxin may function as an activator of plant MAP kinase homologues, as do various mitogens in animal systems.
Dynamic microtubules under the radial and outer tangential walls of microinjected pea epidermal cells observed by computer reconstruction
Authors: Yuan Ming , Warn Richard M. , Shaw Peter J. , Lloyd Clive W. 
Published: March 2003

By microinjecting rhodamine‐conjugated pig brain tubulin into living pea stem epidermal cells it has been possible to follow cortical microtubules beneath the outer tangential wall (OTW) as they re‐orientate from a transverse to a longitudinal alignment. Earlier immunofluorescence studies on fixed material have shown that parallel cortical microtubules circumnavigate the cell forming apparently continuous arrays which are transverse, oblique or longitudinal to the cell’s long axis. If the array re‐orientates as a whole then microtubules along the radial walls would be expected to share the alignment of those on the tangential walls. There are, however, reports that microtubules beneath the outer tangential wall have a different orientation from microtubules at the radial cell walls, raising important questions about the construction and behaviour of the array. Using computer‐rotated stacks of optical sections collected by confocal scanning laser microscopy it has been possible to display the microtubules along radial as well as tangential walls of the same microinjected cells. These observations demonstrate for living epidermal cells that when microtubules are aligned longitudinally at the outer epidermal wall they remain oblique or transverse at the radial walls. The array may not therefore re‐orientate as a whole but seems to undergo re‐organization on only one cell face. However, despite the differing angles between the OTW and radial walls microtubules still form patterns which at the level of the confocal microscope are continuous from one cell face to another, around the cell.It is concluded that some organizing principle attempts to establish overall organization at the cellular level but that this can be perturbed by local re‐organization of dynamic microtubules in subcellular domains. This study emphasizes the importance of the outer epidermal wall and its associated cytoskeleton in initiating changes in the direction of cell expansion.
Induction of cdc2a and cyc1At expression in Arabidopsis thaliana during early phases of nematode‐induced feeding cell formation
Authors: Niebel Andreas , De Almeida Engler Janice , Hemerly Adriana , Ferreira Paulo , Inzé Dirk , Van Montagu Marc , Gheysen Godelieve 
Published: March 2003

SummaryRoot‐knot and cyst nematodes are plant parasites that induce large multinucleated feeding cells in the roots of their hosts. Cytological observations have shown that root‐knot nematodes induce giant cells by cycles of mitosis without cytokinesis whereas cyst nematodes provoke cell wall degradation leading to the formation of a large syncytium. This study was intended to characterize and compare the ability of both types of nematodes to induce progression through the cell cycle. For this purpose, the expression, upon nematode infection, of two cell cycle markers was followed: a marker for division competence, the cyclin‐dependent kinase cdc2a and a marker for the G2 phase, the mitotic cyclin cyc1At. For both types of nematodes, transcriptional activation of these markers was correlated with early phases of feeding cell development. Using molecular markers, it was thus possible to confirm and extend the observations of repeated mitosis in root‐knot nematode‐induced giant cells. Surprisingly, promoter activation of both cdc2a and cyc1At markers was also found upon cyst nematode infection, in feeding cells in which mitosis has not been clearly reported. Incorporation of tritiated thymidine in these syncytia confirms that they progress through the S phase of the cell cycle. One possibility is that cyst nematodes induce cycles of DNA endoreduplication shunting the M phase. Despite obvious differences in ontogeny, common molecular mechanisms, involving cycles of DNA endoreduplication and cdc2a and cyc1At expression, might thus be involved in the formation of a giant cell or a syncytium.