bluuebunny/crossref_metadata_2025 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

Outcrop‐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.
A new species of fungus‐growing ant and its implications for attine phylogeny (Hymenoptera: Formicidae)
Authors: Lattke John E.
Published: March 2003

Abstract. Apterostigma megacephala, a new species of attine ant, is described from Peru and Colombia. It is diagnosed by the following combination of worker characters: flattened compound eyes partially wrapped around conical tubercles, mesonotal denticles and erect rigid pilosity on the head, mesosoma and gaster. It is thought to be a basal species in relation to the rest of Apterostigma. Phylogenetic relationships among basal genera of the tribe Attini are discussed.
Phylogenetic relationship among Libellula, Ladona and Plathemis (Odonata: Libellulidae) based on DNA sequence of mitochondrial 16S rRNA gene
Authors: Kambhampati Srinivas , Charlton Ralph E.
Published: March 2003

Abstract. The type genus for the dragonfly family Libellulidae is Libellula. At present, Libellula s.l. includes twenty‐nine species, whose distribution is largely Nearctic. Whether two other libellulid taxa, Ladona and Plathemis, should be considered synonyms of Libellula, subgenera of Libellula, or separate genera, has been a subject of intermittent debate for over a century. Earlier proposals concerning Ladona and Plathemis were based on a limited number of morphological characters and lacked rigorous phylogenetic analyses. Therefore, we used the DNA sequence of a portion of the mitochondrial 16S rRNA gene and parsimony, maximum likelihood and neighbour‐joining analyses to explore whether Ladona and Plathemis are monophyletic lineages distinct from Libellula. We obtained ≈ 415 bp of DNA sequence from twenty‐three taxa including thirteen species of Libellula s.s., all three recognized species of Ladona, the two species of Plathemis and representatives of four other libellulid genera. Tetragoneuria williamsoni (Odonata: Corduliidae) was included as the outgroup. Parsimony analysis suggested that Ladona and Plathemis are monophyletic lineages distinct from Libellula s.s. with a sister group relationship between Libellula and Ladona. The monophyly of Ladona, Plathemis and Libellula was supported in > 90% of bootstrap replications and in trees five to ten steps longer than the most parsimonious trees. Relationships inferred from maximum likelihood and neighbour‐joining analyses also supported the monophyly of Ladona and Plathemis. The four other libellulid genera included in the study formed a monophyletic clade distinct from Libellula, Ladona and Plathemis. Based on our analysis, we propose that Ladona and Plathemis be considered either genera or subgenera within Libellulidae.
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

Eulophidae 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.
Phylogenetic relationships of tachinid flies in subfamily Exoristinae (Tachinidae: Diptera) based on 28S rDNA and elongation factor‐1α
Authors: Stireman John O.
Published: March 2003

AbstractThe phylogenetic relationships within the largest subfamily of Tachinidae, Exoristinae, were explored using nucleotide sequences of two genes (EF‐1α and 28S rDNA). A total of fifty‐five and forty‐three taxa were represented in the analyses for each gene, respectively, representing forty‐three genera. Neighbour joining, parsimony and maximum likelihood inference methods were employed to reconstruct phylogenetic relationships in separate analyses of each gene, and parsimony was used to analyse the combined dataset. Although certain taxa were highly mobile, phylogenetic reconstructions generally supported recent classification schemes based on reproductive habits and genitalia. Generally, the monophyly of Tachinidae and Exoristinae was supported. Tribes Winthemiini, Exoristini and Blondeliini were repeatedly constructed as monophyletic groups, with the former two clades often occupying a basal position among Exoristinae. Goniini and Eryciini generally clustered together as a derived clade within Exoristinae; however, they were never reconstructed as two distinct clades. These results suggest that the possession of unembryonated eggs is plesiomorphic within the subfamily and that there may have been multiple transitions between microtype and macrotype egg forms.
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°.
Differentiating glacio‐eustacy and tectonics; a case study involving dinoflagellate cysts from the Eocene–Oligocene transition of the Pindos Foreland Basin (NW Greece)
Authors: Peeters  , Hoek  , Brinkhuis  , Wilpshaar  , De Boer  , Krijgsman  , Meulenkamp
Published: March 2003

In an attempt to discriminate between tectonically induced sea‐level changes and glacio‐eustacy, the Ekklissia and Arakthos sections (Epirus, NW Greece) are examined, applying (dinocyst) palynology, sedimentology and magnetostratigraphy. The sections, located in the Pindos Foreland Basin, both comprise the transition from pelagic limestones to hemipelagic silty clays and turbidite sandstones, reflecting the onset of flysch sedimentation as a result of the Pindos thrust activity. Despite an overall tectonic overprint, relative changes of sea level can be reconstructed, using (i) continental/marine palynomorph ratios, (ii) relative abundance of inshore and offshore dinoflagellate cysts, and (iii) taxa indicative of relatively cold and warm sea‐surface temperature, that can be calibrated against the Global Polarity Time Scale (GPTS). Increased fluxes of marginal marine and continental palynomorphs coincide with colder periods on a ‘third‐order’ scale, which thus appear to be related to glacio‐eustatic trends in sea‐level. The larger scale is attributed to the increasing effect of tectonics and acts on a ‘second‐order scale’.
Static stress changes induced by the 1924 Pasinler (M = 6.8) and 1983 Horasan‐Narman (M = 6.8) earthquakes, Northeastern Turkey
Authors: Eyidogan  , Nalbant  , Barka  , King
Published: March 2003

The 1924 Pasinler & 1983 Horasan‐Narman earthquakes which struck the Erzurum region occurred on the NE–SW‐trending Horasan fault zone about 60 km east of Erzurum basin. The inversion of teleseismic seismograms, the aftershock pattern and the surface faulting of the 30 October 1983 (Ms = 6.8) Horasan‐Narman earthquake indicate that it had dominantly left‐lateral motion. One moderately sized aftershock occurred 8 h after the main event and two others a year later on the NE extension of the fault zone. The aftershock distribution dominantly overlapped with the Horasan fault zone, and the aftershocks also migrated from south‐west to north‐east within the year following the mainshock. The results obtained from modelling of static stress changes caused by the 1983 earthquake are consistent with the spatial distribution of aftershocks. Macroseismic observations of the 1924 earthquake (Ms = 6.8) indicated that this event occurred on the SW extension of the Horasan fault zone. Static stress modelling of the 1924 earthquake, by using the same input parameters of the 1983 event, has shown that its occurrence increased the stress in the region of the 1983 rupture zone. The static stress changes caused both by the 1924 and the 1983 earthquakes has increased the failure stress at the NE and SW extensions of the Horasan fault zone and in Narman area. Furthermore, the stress has decreased in the vicinity of the Erzurum fault zone, east of the city of Erzurum, the largest city in eastern Turkey, and in the populated Sarikamis area. This might delay the occurrence of a future probable damaging earthquake in these areas.
Palaeoseismicity of the Dinar fault, SW Turkey
Authors: Altunel E. , Barka A. , Akyüz S.
Published: March 2003

The NW–SE‐trending Dinar fault is an active normal fault upon which the 1 October 1995 earthquake (M = 6.1) occurred. The 1995 earthquake resulted in a c. 10‐km‐long surface rupture with the south side down‐thrown by 50 cm. Investigations of two trench sites perpendicular to the 1995 rupture suggest at least two prior large earthquakes in historical times. Radiocarbon dates and historical records constrain the age of events between 1500
bc and
ad 53, event 2 possibly coinciding with the earthquake that damaged Dinar (the ancient city of Apamea Kibotos) in c. 80
bc and event 1 around 1500
bc. Surface displacements determined for events 1 and 2, compared to the 1995 surface faulting, indicate that M > 6.8 earthquakes were associated with each rupture. Using the total displacement in trenches, a slip rate of about 1 mm yr−1 can be estimated for the Dinar fault. Observations suggest that the return period for large earthquakes in the Dinar area is about 1500–2000 years.
The diamond‐bearing Kokchetav UHP massif in Northern Kazakhstan: exhumation structure
Authors: Theunissen K. , Dobretsov N. , Shatsky V.S. , Smirnova L. , Korsakov A.
Published: March 2003

In the Kokchetav ultrahigh‐pressure (UHP) massif in northern Kazakhstan, diamond‐bearing UHP rocks occur exclusively in a western, rhomb‐shaped domain, that differs from an eastern transpressional domain with coesite‐bearing remnants indicating highest UHP conditions. Different mechanisms may have contributed to the early ascent of the UHP Kokchetav massif. The geometry and structure of the diamond‐bearing domain are interpreted as a sheath‐like fold, coeval with early stage melting. In contrast, the coesite‐bearing domain has a sheet‐like geometry. At mid‐crustal level this early difference in the ascending UHP wedge is reflected in a western rhomb‐horst and an eastern transpression structure, respectively. The latter extends to the east (Borovoye) where the uppermost sequences of the UHP massif were defined by others. Sheath folding is postulated as a suitable mechanism contributing to the early buoyancy‐driven ascent of the subducted rocks, and explains the selective spatial distribution of diamond‐and coesite‐bearing sequences preserved in the wedge.
Initiation of arc magmatism in an embryonic continental rifting zone of the southernmost part of Okinawa Trough
Authors: Chung S.‐L. , Wang S.‐L. , Shinjo R. , Lee C.‐S. , Chen C.‐H.
Published: March 2003

The Okinawa Trough is a young, intracontinental backarc basin that has formed behind the Ryukyu arc–trench system since late Miocene time. In the Southernmost Part of the Okinawa Trough (SPOT), a cluster of active submarine volcanoes delineates a volcanic belt, which is located only ∼100 km above the Wadati–Benioff zone. We report herein new major and trace element data for the SPOT volcanic rocks. These rocks show a compositional range from medium‐K andesite to rhyolite. Their geochemical characteristics are similar to those of pre‐backarc rifting volcanic rocks from the central Ryukyu arc, and different from those of backarc basin lavas from the Middle Okinawa Trough and the post‐backarc rifting Ryukyu arc volcanics. Therefore, despite being topographically contiguous with the rest of the Trough, the SPOT that developed in the Quaternary is not a simple backarc basin but instead an embryonic rift zone in which early arc volcanism occurs as a result of the Ryukyu subduction.
Brittle–ductile deformation in the Glarus thrust Lochseiten (LK) calc‐mylonite
Authors: Badertscher Nicolas P. , Burkhard Martin
Published: March 2003

The Glarus thrust accommodated at least 30 km of northward displacement strongly localized within a 1‐m layer of ‘Lochseiten’ (LK) calc‐mylonite. This layer displays veins in various states of plastic deformation and a wildly refolded foliated gouge texture. Lattice‐ and shape‐preferred orientations are observed within the fine‐grained, recrystallized matrix. These features indicate the alternate activity of brittle and ductile deformation mechanisms. In contrast to the classical view that grain boundary sliding (superplasticity) is the dominant deformation mechanism, it is advocated that fluids, derived from the footwall and expelled along the thrust, are responsible for hydrofracturing and cataclastic deformation. In periods between fracture events, deformation was ductile. In this new interpretation, a substantial amount of the total thrust displacement was accommodated by numerous short‐lived and strongly localized fracture events at the base of the Verrucano thrust sheet, rather than a permanently weak décollement lithology.
Ostracods and palaeobotany from the middle Permian of Oman: implications on Pangaea reconstruction
Authors: Crasquin‐Soleau Sylvie , Broutin Jean , Besse Jean , Berthelin Martine
Published: March 2003

Discovery of a middle Permian ostracod fauna in the marine Khuff Formation (Sultanate of Oman), combined with palaeobotanical data from the immediately underlying continental Gharif Formation, supports new interpretations of the palaeobiogeography of the Tethys during the late Palaeozoic. A mixed ostracod fauna existed on the Arabian platform. This new record of Permian ostracods, combined with recent data obtained in other Tethyan areas, emphasizes the close relationship between the south‐western Tethys realm and South China. The macro‐ and microfloral assemblages of the continental Gharif Formation demonstrate that this palaeoflora represents a true mixed association in which Gondwanan, Cathaysian and Euramerian elements are intermingled. Two main models exist for the reconstruction of Pangaea during the late Palaeozoic. Both ostracods and palaeobotanical evidence favour the reduction of the oceanic area between South China and Arabian plate as in the B Pangaea model favoured by recent palaeomagnetic data.
The cooling of frontal flow ramps: a calorimetric study on the Rocche Rosse rhyolite flow, Lipari, Aeolian Islands, Italy
Authors: Gottsmann J. , Dingwell D. B.
Published: March 2003

Relaxation geospeedometry using differential scanning calorimetry (DSC) has been applied to quantify the cooling history across the glass transition of flow ramps at the front of the calc‐alkaline rhyolite Rocche Rosse flow of Lipari, Aeolian Islands, Italy. Modelled cooling rates for the obsidian retrieved from two profiles range between 0.2 and 0.03 K min–1. Cooling at the flow front appears to be dominated by conductive heat loss of individual flow ramps forming individual cooling units. Cooling rates of tens of Kelvins per day appear to have controlled the last stage of viscous deformation before the entire flow came to rest. It is inferred that cooling rates slower than those modelled are required to sustain flow in highly viscous rhyolitic lavas.
Drainage network expansion of the Salagou drainage basin (S. France): an example of relief response to recent climate change?
Authors: Bonnet Stéphane , Besnard Mélanie , Van den Driessche Jean
Published: March 2003

Continental erosion is known to be strongly controlled by climate but the way by which geomorphological systems respond to climate change still remains poorly understood. Recent numerical modelling suggests that drainage networks are subjected to strong spatial fluctuations but few studies of natural systems have addressed this phenomenon because of the difficulty of documenting the evolution of erosional landscapes. A detailed field analysis has allowed reconstruction of the past topography of a drainage basin located in southern France where remnants of a past landscape are well preserved. A change from a smooth to a present‐day dissected landscape is observed and related to a change in the dominant processes of erosion. This evolution is interpreted in terms of fluctuations in drainage network extent in response to a Holocene increase in precipitation.
Crustal uplift in the Alps: why the drainage pattern matters
Authors: Schlunegger Fritz , Hinderer Matthias
Published: March 2003

The Alpine drainage system comprises two large orogen‐parallel drainage basins in the core of the Alps (the Rhone and Rhine valleys), and smaller orogen‐normal orientated systems. Discharge of the large rivers is ≈5–10 higher than that of the small ones. In addition, the courses of the Rhone and Rhine Rivers are trapped by faults and thrusts that display lower erosional resistance than the neighbouring lithologies. Enhanced discharge of these rivers and the low erosional resistance of their bedrocks potentially enhances surface erosion. Indeed, present‐day and glacial sediment yields are ≈1.6–1.7 times higher in these valleys than in the orogen‐normal systems. Interestingly, rates of crustal uplift are also enhanced in the Rhine and Rhone valleys, where current rates of ≈1.4–1.6 mm yr−1 are measured. The spatial coincidence between the location of enhanced erosion and maximum crustal uplift rates are interpreted to reflect a positive feedback between surface erosion and tectonic forcing.
Fibrous illite in oilfield sandstones – a nucleation kinetic theory of growth
Authors: Wilkinson Mark , Haszeldine R. Stuart
Published: March 2003

Fibrous illite is one of the most important cements that grows within sandstones during burial, and the only one which is commonly dated using the K–Ar age technique. A small quantity of illite can dramatically reduce porefluid flow rates within a sandstone, thus making oil recovery uneconomic. Illite ages potentially correspond to geological events such as hydrocarbon filling of a sandstone reservoir, providing calibration to basin models. Yet the fundamental processes controlling fibrous illite growth are not understood. This contribution presents a new theory for illite growth within sandstones that explains the fibrous morphology of illite, the restricted range of illite K–Ar age dates compared to the age of the host sandstones, and the lack of 0‐Myr‐old illite reported. The growth of fibrous illite as an authigenic cement may be controlled by nucleation kinetics, and not by thermodynamic or growth kinetic considerations as has been previously assumed.
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

YAC 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

The 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

A 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

The 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

A 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.
A mutation causing variegation and abnormal development in tobacco is associated with an altered mitochondrial DNA
Authors: Bonnett H.T. , Djurberg I. , Fajardo M. , Glimelius K.
Published: March 2003

A variegated mutation appeared in the leaves of a tobacco cybrid plant resulting from fusion of protoplasts from tobacco with Petunia. The mutation was inherited maternally. The light green coloration of leaf sectors resulted from a substitution of spongy parenchyma for palisade parenchyma. No defects were detected in the chloroplasts of the plants, which were derived from Petunia. The mitochondria, as judged by the electrophoretic pattern of their DNA after digestion with restriction endonucleases, were very similar to mitochondria of tobacco, although with some unique cybrid‐specific fragments. A second round of fusions was performed to confirm that mitochondria, rather than chloroplasts, were associated with the variegated phenotype. In these fusions, the Petunia chloroplasts of the variegated plants were replaced by tobacco chloroplasts. The mitochondria, according to the DNA restriction pattern, retained all or some of the unique cybrid‐specific fragments found in the original variegated tobacco cybrid. Since the variegated phenotype remained after the chloroplast exchange, the chloroplast DNA cannot be the site of the mutation which is responsible for the mutant phenotype. This result eliminates the chloroplast and confirms that the mitochondrial genome is associated with the mutant phenotype.
BPF‐1, a pathogen‐induced DNA‐binding protein involved in the plant defense response
Authors: Da Costa e Silva Oswaldo , Klein Ludger , Schmelzer Elmon , Trezzini Giampiero F. , Hahlbrock Klaus
Published: March 2003

The mechanisms by which plants restrict the growth of pathogens include transient activation of numerous defense‐related genes. Box P is a putative cis‐acting element of a distinct group of such genes, including those encoding the enzyme phenylalanine ammonia‐lyase (PAL). A DNA‐binding activity to Box P was identified in nuclear extracts from cultured parsley cells and a cDNA encoding the protein BPF‐1 (Box P‐binding Factor) partially characterized. BPF‐1 binds to this element with specificity similar to that of the binding activity in nuclear extracts. BPF‐1 mRNA accumulates rapidly in elicitor‐treated parsley cells and around fungal infection sites on parsley leaves. This accumulation is, at least partly, due to a rapid and transient increase in the transcription rate of BPF‐1. Moreover, tight correlation between the relative amounts of BPF‐1 and PAL mRNAs was observed in different organs of a parsley plant. These results are consistent with the hypothesis that BPF‐1 is involved in disease resistance by modulating plant defense gene expression.
A plant gene with homology to d‐myo‐inositol‐3‐phosphate synthase is rapidly and spatially up‐regulated during an abscisic‐acid‐induced morphogenic response in Spirodela polyrrhiza
Authors: Smart Cheryl C. , Fleming Andrew J.
Published: March 2003

The induction of turions (dormant vegetative buds) by the plant growth regulator abscisic acid (ABA) in the aquatic angiosperm Spirodela polyrrhiza is one of the few examples of a plant hormone triggering a morphogenic response. In order to aid our understanding of the molecular basis of this phenomenon a cDNA library has been prepared from ABA‐induced S. polyrrhiza and by differential screening a number of early ABA‐up‐regulated genes have been isolated. This paper reports the characterization of one such cDNA (tur1) from S. polyrrhiza which codes for a protein highly homologous to yeast d‐myo‐inositol‐3‐phosphate synthase (EC.5.5.1.4), the catalyst for the first committed step in inositol biosynthesis. This is the first reported cloning of a plant gene involved in inositol production. It is shown by Northern analysis and in situ hybridization that ABA induces a rapid preferential up‐regulation of this gene and that this is localized to the stolon tissue. The stolon connects the developing turion to the node of the mother frond (the meristematic region involved in the production of turions which arise as a morphogenic response to this hormone). This increase in tur1 transcript level is accompanied by a rise in the activity of d‐myo‐inositol‐3‐phosphate synthase. The possible role of inositol in ABA‐induced events during turion formation is discussed.
The nitrogen response of a barley C‐hordein promoter is controlled by positive and negative regulation of the GCN4 and endosperm box
Authors: Müller Martin , Knudsen Søren
Published: March 2003

The 431 bp C‐hordein promoter of λ‐1‐17 exhibits a specific response to amino acids and NH4NO3 in developing barley (Hordeum vulgare L.) endosperms. With the aid of particle bombardment it is shown that the GCN4 motif ATGA(C/G)TCAT is the dominating cis‐acting element in this response. But synergistic interaction with the neighbouring endosperm motif TGTAAAGT within the bifactorial prolamin element and cooperation with upstream sequences including a second prolamin‐like element is an absolute requirement for a strong, positive regulation by an optimal nitrogen regime. Low nitrogen levels convert the GCN4 box into a negative motif. In contrast the endosperm box on its own exerted a silencing activity, independent of nitrogen nutrition. Sequence comparisons revealed that GCN4‐ and endosperm‐like motifs are widely distributed among plant promoters. Their putative role in nitrogen regulation is discussed.
Activation of a tobacco glycine‐rich protein gene by a fungal glucan preparation
Authors: Brady Kevin P. , Darvill Alan G. , Albersheim Peter
Published: March 2003

A Phytophthora megasperma f.sp. glycinea cell wall glucan preparation was previously shown to protect tobacco plants against viral infection. Eleven plant defense‐related genes were assayed for elevated mRNA accumulation levels in response to glucan treatment of tobacco plants. The expression of only one of these genes, a glycine‐rich protein (GRP) gene, was induced by glucan application. Elevated GRP gene mRNA levels could be detected within 15 min of glucan treatment and reached maximum levels at 4 h post‐treatment followed by a slow decline to 8 h. The maximum induction of the GRP gene was approximately ninefold above H2O‐treated control plants. Northern blot analysis showed that a single mRNA species of 1.4 kb was responding to the glucan treatment. GRP genes occur in tobacco as members of a multigene family, but only one specific GRP gene was induced by the glucan treatment. A genomic copy of this responding GRP gene was cloned and sequenced. This tobacco GRP gene is homologous to the petunia ptGRP1 gene and the French bean GRP1.8 gene, but is not closely related to the French bean GRP1.0 gene. GRP gene expression has previously been associated with disease resistance in plants, but it remains to be determined whether β‐glucan activation of the tobacco GRP gene results in the observed resistance to virus.
Molecular characterization of two cDNAs from Sinapis alba L. expressed specifically at an early stage of tapetum development
Authors: Staiger Dorothee , Apel Klaus
Published: March 2003

Flower formation in the long‐day plant Sinapis alba is strictly dependent on an inductive light treatment. Differential screening of an apex cDNA library prepared 10 days after flower induction against cDNAs from vegetative apices has identified two cDNA clones, pSFD10.35 and pSFD10.44, which represent transcripts expressed transiently between day 10 and day 20 after induction and which disappear before flowers reach maturity. The corresponding full‐length cDNAs which were isolated, Satap35 and Satap44, display 86% overall sequence identity. These cDNAs encode polypeptides with predicted molecular weights of 12.7 and 12.4 kDa, and isoelectric points of 10.4 and 7.5, respectively. The N‐terminal portions of the open reading frames have characteristics of signal sequences. In situ hybridization reveals that both transcripts are localized exclusively in the tapetal cell layer of the anthers. Maximal expression is observed in flower buds of approximately 1.5 mm length (tetrad stage). Southern blot analysis demonstrates the presence of additional, closely related genes in the Sinapis genome, as well as the occurrence of homologous genes in Arabidopsis thaliana, Brassica napus and Nicotiana tabacum.
Cell fate in the inflorescence meristem and floral buttress of Arabidopsis thaliana
Authors: Furner Ian J. , Pumfrey Joanne E.
Published: March 2003

The flowers and leaves of Arabidopsis are arranged in a spiral with successive organs positioned at intervals of approximately 140°. This simple phyllotaxy determines the organization of the flowers of the inflorescence. Here we describe the analysis of X‐ray‐induced albino sectors in the L2 layer of the Arabidopsis inflorescence. No evidence was found of lineage restrictions within the inflorescence meristem. Comparison of the spatial relationships between albino and green tissue in the sepals of 43 chimeric inflorescences allowed the generation of a three‐dimensional fate map. The map relates the initiation of flowers in the plant apex to their final arrangement. The map was found to be a shallow dome with phyllotaxy superimposed on its surface. A similar map was prepared of the floral buttress and this was found to be a ridge with sepal primordia at its edges. Unlike other fate maps of plants these maps relate the relative positions and sizes of organ primordia in terms of the frequency with which they are of the same somatic phenotype, and not the number of cells giving rise to them.
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

Three 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

Ferredoxin 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

Two 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.