bluuebunny/crossref_metadata_2025 huggingface dataset:
Holocene storage of siliciclastic sediment around islands on the middle shelf of the Great Barrier Reef Platform, north‐east Australia
Authors: Heap A. D. , Dickens G. R. , Stewart L. K. , Woolfe K. J.
Published: March 2003

Thick sequences of sediment surround the Whitsunday Islands on the middle shelf of the Great Barrier Reef (GBR) Platform. Much of this sediment is siliciclastic material deposited since the sea‐level highstand at around 6·5 ka. This raises a mass balance dilemma because modern terrigenous discharge to the GBR Platform is restricted to the inner shelf. Shallow seismic profiles and sediment samples were collected over 450 km2 around the Whitsunday Islands to quantify the mass of siliciclastic sediment for a dynamic model of the shelf. The sea floor and pre‐Holocene surfaces were mapped using 4584 stations along the seismic profiles and a graphical computer program. The total volume of sediment between these two surfaces is 3·67 ± 0·45 × 109 m3. This volume is composed of buried reefs (0·13 ± 0·01 × 109 m3), medium‐ (0·70 ± 0·30 × 109 m3) and fine‐grained shoals (2·84 ± 0·35 × 109 m3). The volume estimates combined with measurements of carbonate concentration, density and porosity indicate that 1850 ± 380 Mt of Holocene siliciclastic sediment surround the Whitsunday Islands in medium‐ (510 ± 225 Mt) and fine‐grained shoals (1340 ± 155 Mt). The total mass of siliciclastic material is 1·7–2·6 times that stored in Cleveland Bay, a similar sized repository on the inner shelf. A simple numerical model has been constructed to explain this large quantity of Holocene siliciclastic sediment. The model results in the appropriate siliciclastic mass next to the Whitsunday Islands by integrating regional shelf processes over time. Unlike the present day, rivers discharged sediment to the middle shelf during the early Holocene. This material was subsequently focused by northward transport into the vicinity of the islands, a geomorphologically complex region that serves as a sediment trap. Although direct riverine inputs to the middle shelf have stopped during the present sea‐level highstand, previously deposited siliciclastic sediment is continually being winnowed from the middle shelf and redeposited next to the Whitsunday Islands. The transport and distribution of siliciclastic sediment on the GBR Platform is thus influenced significantly by storage around islands on the middle shelf.
A phylogenetic analysis of higher‐level gall wasp relationships (Hymenoptera: Cynipidae)
Authors: LILJEBLAD JOHAN , RONQUIST FREDRIK
Published: March 2003

We present the most comprehensive analysis of higher‐level relationships in gall wasps conducted thus far. The analysis was based on detailed study of the skeletal morphology of adults, resulting in 164 phylogenetically informative characters, complemented with a few biological characters. Thirty‐seven cynipid species from thirty‐one genera, including four genera of the apparently monophyletic Cynipini and almost all of the genera in the other tribes, were examined. The outgroup included exemplar species from three successively more distant cynipoid families: Figitidae (the sister group of the Cynipidae), Liopteridae and Ibaliidae. There was considerable homoplasy in the data, but many groupings in the shortest tree were nonetheless well supported, as indicated by bootstrap proportions and decay indices. Partitioning of the data suggested that the high level of homoplasy is characteristic of the Cynipidae and not the result of the amount of available phylogenetically conservative characters being exhausted. The analysis supported the monophyly of the Cynipini (oak gall wasps) which, together with the Rhoditini (the rose gall wasps), Eschatocerini and Pediaspidini formed a larger monophyletic group of gall inducers restricted to woody representatives of the eudicot subclass Rosidae. The inquilines (Synergini) were indicated to be monophyletic, whereas the Aylacini, primarily herb gall inducers, appeared as a paraphyletic assemblage of basal cynipid groups. The shortest tree suggests that the Cynipidae can be divided into three major lineages: one including the inquilines, the Aylacini genera associated with Rosaceae, and Liposthenes; one consisting entirely of Aylacini genera, among them Aulacidea, Isocolus and Neaylax; and one comprising the woody rosid gallers (the oak and rose gall wasps and allies), the Phanacis‐Timaspis complex and the Aylacini genera associated with Papaveraceae.
Phylogeny of the bee genus Lasioglossum (Hymenoptera: Halictidae) based on mitochondrial COI sequence data
Authors: Danforth Bryan N.
Published: March 2003

The bee genus Lasioglossum Curtis is a model taxon for studying the evolutionary origins of and reversals in eusociality. This paper presents a phylogenetic analysis of Lasioglossum species and subgenera based on a data set consisting of 1240 bp of the mitochondrial cytochrome oxidase I (COI) gene for seventy‐seven taxa (sixty‐six ingroup and eleven outgroup taxa). Maximum parsimony was used to analyse the data set (using
paup*4.0) by a variety of weighting methods, including equal weights, a priori weighting and a posteriori weighting. All methods yielded roughly congruent results. Michener’s Hemihalictus series was found to be monophyletic in all analyses but one, while his Lasioglossum series formed a basal, paraphyletic assemblage in all analyses but one. Chilalictus was consistently found to be a basal taxon of Lasioglossum sensu lato and Lasioglossum sensu stricto was found to be monophyletic. Within the Hemihalictus series, major lineages included Dialictus + Paralictus, the acarinate Evylaeus + Hemihalictus + Sudila and the carinate Evylaeus + Sphecodogastra. Relationships within the Hemihalictus series were highly stable to altered weighting schemes, while relationships among the basal subgenera in the Lasioglossum series (Lasioglossum s.s., Chilalictus, Parasphecodes and Ctenonomia) were unclear. The social parasite of Dialictus, Paralictus, is consistently and unambiguously placed well within Dialictus, thus rendering Dialictus paraphyletic. The implications of this for understanding the origins of social parasitism are discussed.
Phylogeny of Prosciara Frey and related genera (Diptera: Sciaridae)
Authors: Vilkamaa Pekka
Published: March 2003

The phylogeny of Phytosciara Frey, Prosciara Frey, Dolichosciara Tuomikoski (together forming Phytosciara sensu Tuomikoski), Lobosciara Steffan and Bradysia Winnertz was studied by parsimony analysis using the computer programs Pee‐Wee and NONA. The analysis was based on sixty‐four morphological characters from adult males, coded for thirty‐nine ingroup and two outgroup terminals. Three cladograms of the maximum fit (Pee‐Wee) and one of the minimum length (NONA) were obtained, some of them with polytomies. Many characters showed much homoplasy in the cladograms. The solution by the fittest cladograms was chosen as the main hypothesis of the phylogeny. Of the groups studied, only Lobosciara appeared monophyletic. The relationships of the taxa in their now revised monophyletic sense are: Dolichosciara + (Lobosciara + ((‘Prosciara’ fuscina group + ‘P’. vulcanata) + (‘P’. mima group + ((‘P’. perfida + (Bradysia + Phytosciara)) + Prosciara)))). Phytosciara Frey, Prosciara, Dolichosciara and Lobosciara in their revised concepts are regarded as genera.
Morphological and molecular identity of Anopheles (Cellia) sundaicus (Diptera: Culicidae), the nominotypical member of a malaria vector species complex in Southeast Asia
Authors: Linton Yvonne‐Marie , Harbach Ralph E. , Seng Chang Moh , Anthony Thomas G. , Matusop Asmad
Published: March 2003

A neotype for Anopheles (Cellia) sundaicus (Rodenwaldt), the nominotypical member of a malaria vector species complex, is selected from the progeny of a female collected at Pandan Beach near Lundu, Sarawak, Malaysia. Siblings of the neotype and other topotypic specimens are used to characterize and fix the morphological and molecular identity of the species as a foundation for systematic studies of the species complex. The species is described and illustrated in the adult, pupal and larval stages, and DNA sequence data are included for the mitochondrial cytochrome c oxidase I (COI) gene and the nuclear ITS‐2 region.
A new leucopine genus (Diptera: Chamaemyiidae) with species attacking Ceroplastes wax scales (Hemiptera: Coccidae) in South America
Authors: Gaimari Stephen D. , Tanasijtshuk Vitali N.
Published: March 2003

Abstract. A new genus, Echinoleucopis, is proposed within Chamaemyiidae (Diptera). This leucopine genus clearly differs from other Chamaemyiidae in the high lunule, reduction and fusion of spermathecae in females and rounded form of puparia. Within Echinoleucopis, five new species (bennetti, grioti, iota, macula and nigrolinea) are described, in addition to lectotype designation, redescription and recombination for the type species of the genus, Leucopina ceroplastophaga Blanchard. Phylogenetic relationships among the included taxa are hypothesized. All known species of the genus are from South America and are predators on eggs within an ovisac of wax scales in genus Ceroplastes Gray (Hemiptera: Coccidae).
Phylogenetic relationships among microgastrine braconid wasp genera based on data from the 16S, COI and 28S genes and morphology
Authors: WHITFIELD JAMES B. , MARDULYN PATRICK , AUSTIN ANDREW D. , DOWTON MARK
Published: March 2003

AbstractPhylogenetic relationships among the genera of the large braconid wasp subfamily Microgastrinae were explored using DNA sequence data from the mitochondrial large ribosomal subunit (16S), nuclear large ribosomal subunit (28S) and mitochondrial cytochrome oxidase (COI) genes, along with morphological characters, both new and from previous studies. The taxonomic history of this group of wasps is reviewed, along with a critique of previous phylogenetic studies on the group. Molecular data were sampled from forty‐six species representing twenty‐six genera of microgastrines, plus three species representing the close outgroup taxa Cardiochilinae and Miracinae. Some 2300 base pairs of aligned sequence were obtained per taxon from the three genes. In addition, fifty‐three morphological characters were coded for all known genera, including two undescribed genera, exceptSemionisNixon (known from only a single male type specimen). Relationships among several groups of genera are clarified and challenge some major assumptions made in earlier classifications. In particular, it is clear that dependence on one or a few major morphological character systems oversimplifies relationships, and can lead to misleading results. Despite the large amount of data analysed, basal divergences within the subfamily remain poorly resolved and essentially unsupported in any rigorous statistical sense.
A phylogenetic analysis of the extant Aeshnidae (Odonata: Anisoptera)
Authors: Von Ellenrieder Natalia
Published: March 2003

Abstract A cladistic analysis of the world Aeshnidae is presented, based on fifty‐eight characters of adult and larval anatomy. The ingroup taxa include all the extant genera of Aeshnidae, and the austropetaliid genera Phyllopetalia and Hypopetalia were chosen as the outgroup. The strict consensus tree obtained after successive weighting shows that the subgroups defined traditionally for Aeshnidae are paraphyletic or polyphyletic. The previous reclassification derived from analyses based on wing venation is supported in terms of the monophyly of Aeshnidae, Gomphaeschninae and its sister group comprising the remaining Aeshnidae. Gomphaeschninae is confirmed as sister group of the remaining Aeshnidae (= Aeshnodea Bechly). The sister‐group relationships between Gomphaeschna+Sarasaeschna and Linaeschna+Oligoaeschna are corroborated. Within Aeshnodea, three monophyletic groups emerged: Boyeria + (Petaliaeschna+ (Limnetron+Gynacanthaeschna+Periaeschna)) + ((Cephalaeschna+Caliaeschna) + (Allopetalia (Notoaeschna+Spinaeschna))); Dendroaeschna+ (Epiaeschna+ (Aeschnophlebia+ (Nasiaeschna+ (Tetracanthagyna+Brachytron)))); and Polycanthagyna+ (Basiaeschna+ (Amphiaeschna+ (Indaeschna+ (Oplonaeschna+ (Racenaeschna+Plattycantha+Agyrtacantha+Triacanthagyna+ (Subaeschna+Austrogynacantha+Gynacantha) + (Heliaeschna+ (Neuraeschna+Staurophlebia))) + ((Castoraeschna+Coryphaeschna+Remartinia) + (Oreaeschna+ (Aeshna+ (Anaciaeschna+ ((‘A.’isosceles+Andaeshna) + (Anax+Hemianax)))))). Additional informative characters are required to test the relationships suggested here between the main groups of Aeshnodea and some enigmatic basal taxa (Antipodophlebia, Austroaeschna, Acanthaeschna, Telephlebia, Austrophlebia and Planaeschna).
Proterozoic melting in the northern peridotite Massif, Zabargad Island: Os isotopic evidence
Authors: Snow  , Schmidt
Published: March 2003

The geodynamic history of the three Zabargad peridotite bodies is the key to their significance as samples of the upper mantle. Currently, there are two main hypotheses that differ greatly in their implications for the origin and age of the peridotite complex as a whole. In the first, the Zabargad peridotite bodies all represent young asthenospheric mantle that was juxtaposed with ancient crustal gneisses during the opening of the Red Sea. In the second, the complex may represent a single package of residual mantle and lower crust of Pan‐African age that was uplifted during the Miocene. In order to distinguish between these two models, we have analysed five samples of Zabargad peridotite and two pyroxenites for Os isotopes. The 187Os/188Os results range from 0.1198 to 0.1320 and correlate with Al2O3, allowing an age inference for the northern body, based on the Os isotopic evolution curve for the bulk Earth, of 1.4±0.3 Gyr. This is at least as old as the previously inferred Pan‐African age and may be older, and agrees with previous suggestions that the northern and central peridotite bodies probably represent ancient continental lithospheric mantle, while the southern body represents recent asthenospheric mantle. Our results from both central and southern bodies are consistent with either crustal age hypothesis.
The erosion history of the Central Alps: evidence from zircon fission track data of the foreland basin sediments
Authors: Spiegel C. , Kuhlemann J. , Dunkl I. , Frisch W. , Von Eynatten H. , Balogh K.
Published: March 2003

Fission track dating on detrital zircons of Alpine debris in the Swiss molasse basin provides information about the erosion history of the Central Alps and the thermal evolution of source terrains. During Oligocene times, only sedimentary cover nappes, and Austroalpine basement units were eroded. Incision into Austroalpine basement units is indicated by increasing importance of Cretaceous cooling ages in granite pebbles upsection. Erosion of Penninic basement units started between 25 and 20 Ma. Early Oligocene zircon FT ages show that Penninic basement units were exposed at ∼20 Ma. Deeper Penninic units of the Lepontine Dome became exposed first at ∼14 Ma, contemporaneously with the opening of the Tauern window in the Eastern Alps. A middle Miocene cooling rate of 40 °C Myr−1 is deduced for the Lower Penninic units of the Lepontine Dome.
Evidence for an active sinistral shear zone in the western Alboran region
Authors: Andeweg B. , Cloetingh S.
Published: March 2003

A compilation of gravity, seismicity, neotectonics, geology, tomography and topography data from the Alboran region reveals distinctive differences between the eastern and western part of the Alboran region and Betic Cordillera. Calculated profiles of integrated crustal strength reveal that lateral differences in mechanical behaviour are caused by marked inherited differences in crustal make‐up. The two domains with different tectonic behaviour are separated by a N025°‐trending lineament in the western Alboran and central Betic Cordillera. This lineament can be interpreted as an upper mantle – lower crustal sinistral shear zone accommodating a large part of the convergence between Africa and Iberia.
Melt migration and mechanical state in the lower crust of oceanic ridges
Authors: Nicolas A. , Poliakov A.
Published: March 2003

Below the melt lens of fast spreading ridges, a low seismic velocity zone has been identified. From the study of ophiolite gabbros, in particular in Oman, this domain has been interpreted as a large magma chamber filled by a melt‐poor mush where granular flow controlled by pressure solution‐crystallization predominates over plastic flow. Melt migration through the mush is difficult to study in the field because the large magmatic flow taking place in this magma chamber has erased nearly all traces of migration paths. It is, however, still possible to identify sills and former dikes, now largely transposed into the layering. Physical traces for porous flow are rare, but petrological and geochemical evidence suggests that it also contributed to melt migration. Finally, in the lower gabbro horizons large magmatic folds and brecciated zones may bear evidence for magmatic intrusions. The combination of diking, porous flow and large‐scale intrusions to carry melt through the magma chamber may be explained by the granular behaviour of the medium. It is suggested that the melt film present between grains and clots of grains reduces the large cohesive forces which characterize a solid, plastic, medium. Melt migration through the mush may thus depend on the size of cohesive clots, evolving through time and space, from porous flow to diking and melt intrusions for increasing larger clots. This process is illustrated by a physical experiment on pressurized air circulation through a granular medium.
Geothermal palaeogradients and metamorphic zonation from the conodont colour alteration index (CAI)
Authors: García‐López Susana , Bastida Fernando , Aller Jesús , Sanz‐López Javier
Published: March 2003

The conodont colour alteration index (CAI) is potentially valuable in thermal history investigations, but there are problems in its use. An approach is proposed herein to overcome the problem of establishing reliable geothermal palaeogradients in areas with burial metamorphism, based on knowledge of the stratigraphic succession thickness, the boundaries of chronostratigraphic units, and the age and duration of deformation episodes. Although also problematical that a correlation between CAI and Kübler index (KI) values does not exist, there are areas where CAI and KI values are notably consistent for the anchizone boundaries; however, anomalous correlations between CAI and KI values have also been found in some areas. A CAI anchizone (or ancaizone) is defined in order to enable CAI values to be used independently to establish a metamorphic zonation.
Contamination of mafic magma by partial melting of dolomitic xenoliths
Authors: Wenzel T. , Baumgartner L. P. , Brügmann G. E. , Konnikov E. G. , Kislov E. V. , Orsoev D. A.
Published: March 2003

Mg‐skarns enclosed in dunite cumulates of the Neo‐Proterozoic Ioko‐Dovyren intrusion (northern Baikal region, Russia) can be traced to silica‐poor dolomitic host rock layers. The dominant minerals of the skarns are brucite (pseudomorph after periclase), forsterite and Cr‐poor spinel. Rapid heating of quartz‐poor dolomitic xenoliths led to the formation of minor olivine, followed by the breakdown of dolomite to calcite and periclase. Xenoliths were partially melted upon further heating resulting in a calcite melt. This low‐density melt was quantitatively squeezed out, mixed with the surrounding mafic magma and left behind periclase and olivine. This caused the crystallization of new olivine with elevated CaO contents in zones above skarn‐bearing horizons. Mixing of calcite melt with the surrounding mafic magma also resulted in the crystallization of Cats‐rich clinopyroxene instead of plagioclase. The mineralogy of contaminated dunite cumulates is consistent with assimilation of approximately 4wt% CaO by the Ioko‐Dovyren mafic magma.
Earthquake‐induced chemical changes in the thermal waters of the Umbria region during the 1997–1998 seismic swarm
Authors: Favara R. , Italiano F. , Martinelli G.
Published: March 2003

The compositional data collected at three thermal springs in the Umbria region over a sampling period lasting two and a half hydrological years included the entire seismic sequence striking the Central Apennines (Italy) in 1997–1998. Wide temporal variations in the chemical composition and temperature of thermal waters were observed at all the sampling sites. The widest were recorded at the Triponzo sampling site, where a temperature drop of 2 °C and 20 °C preceded, by 4 days and 2 days, respectively, the occurrence of the event characterized by the deepest hypocentre of the entire seismic sequence. Despite such a macroscopic preseismic anomaly, the recorded variations were not related to single seismic events or to the release rate of the seismic energy. They actually seem to have been induced by permeability variations related to crustal deformation in the absence of elastic energy release and were thus linked to the whole seismogenic process.
Timing of neotectonic fracturing by fission track dating of obsidian in‐filling faults in the İkizdere–Rize area, NE Black Sea region, Turkey
Authors: Yeğingil Zehra , Boztuğ Durmuş , Er Murat , Oddone Massimo , Bigazzi Giulio
Published: March 2003

There are several NE–SW‐ and NNW–SSE‐trending sets of neotectonic faults that are infilled with obsidians in the İkizdere–Rize district of the NE Black Sea region, Turkey. Using the fission‐track technique, it is estimated that these fracture‐filling obsidians were formed between 1.73 ± 0.10 and 1.93 ± 0.15 Ma. This short period is consistent with a unique eruption, and is supported by petrographic and geochemical data that reveal very homogenous characteristics. Although existing literature data indicate that these faults are part of the early Pliocene neotectonic fracture system in this region, the determination of latest Pliocene–Pleistocene formation for the İkizdere obsidians better constrains its timing.
Physical and mechanical properties of selected amphibolite core samples from the Kola Superdeep Borehole KSDB‐3
Authors: Trčková Jiřina , Živor Roman , Přikryl Richard
Published: March 2003

Laboratory tests of physical and mechanical properties were performed on amphibolites representing two units from the Kola Superdeep Borehole KSDB‐3 (Russia) − the Proterozoic Karelian Complex (depths of 3043 m, 3530 m and 4389 m) and the Archean Kola–Belomorian Complex (depths of 7951 m, 8942 m and 9904 m). Obtained grain density and bulk density values are nearly identical for all tested samples, but porosities increased slowly with depth. Marked differences in strength properties were found between amphibolite samples from the Karelian Complex and amphibolite samples from the Kola–Belomorian Complex. The uniaxial compressive strength of the samples from the lower part of the borehole is significantly smaller than in samples from the upper part; a similar trend was found for triaxial tests. The values of the deformation modulus, Young's modulus and Poisson's ratio obtained from samples of the Karelian Complex are considerably higher than those from the Kola–Belomorian Complex. Observed mechanical properties are explained by the variable grain‐size distribution and by the spatial arrangement of main rock‐forming minerals. These properties are also influenced by recovery of rocks from great depths.
Isolation and molecular characterization of PosF21, an Arabidopsis thaliana gene which shows characteristics of a b‐Zip class transcription factor.
Authors: Aeschbacher RA , Schrott M , Potrykus I , Saul MW
Published: March 2003

We have isolated a putative transcription factor gene, PosF21, from Arabidopsis thaliana using an indirect cross‐hybridization approach. cDNA clones were isolated which encode single repeating amino acids. Such sequences may function as activation domains in transcription factors and may be indicative for such proteins. The clone PosF21 encodes a region very rich in glutamines. Besides this putative activation domain it encodes a protein sequence which shows all the characteristics of a basic‐domain/leucine zipper type of DNA‐binding domain. PosF21 is expressed constitutively at a low level in young seedlings and in roots, stems and leaves of mature Arabidopsis plants. A genomic clone of PosF21 was isolated and the gene structure was analyzed. Related sequences in Arabidopsis and a wide range of other plants were detected using the putative DNA‐binding domain as a probe in cross‐hybridization experiments. Transient transformations in tobacco protoplasts were performed using the beta‐glucuronidase (GUS) gene as reporter gene. Approximately 400 bp of the 5' genomic region of PosF21 promote expression of the GUS gene in tobacco protoplasts. Evidence for a regulatory function of PosF21 was obtained since co‐ expression of the full PosF21 protein or its DNA‐binding region alone specifically stimulated GUS gene expression directed from the PosF21 promoter by 6‐8‐fold.
Inhibition of tobacco nitrite reductase activity by expression of antisense RNA
Authors: Vaucheret Hervé , Kronenberger Jocelyne , Lepingle Andrée , Vilaine Françoise , Boutin Jean‐Pierre , Caboche Michel
Published: March 2003

A tobacco nitrite reductase (NiR) cDNA and its corresponding gene were isolated from cDNA and genomic libraries. An NiR antisense mRNA was expressed in transgenic tobacco under the control of a double 35S promoter. Transformants were obtained on a medium containing ammonium as the sole source of nitrogen. One plant growing normally on ammonium but displaying drastically reduced development and chlorotic leaves when grown on nitrate as the sole source of nitrogen was studied further. This plant accumulated nitrite fivefold over wild‐type level and showed reduced amounts of ammonium (11% wild‐type level), glutamine (19%), and total protein (8%). NiR mRNA and activity were below detectable levels. Under these conditions, nitrate reductase (NR) activity and mRNA were overexpressed, suggesting that N‐metabolites resulting from nitrate reduction are responsible for the repression of the expression of the NR gene, independently from the presence or absence of a functional NR protein.
Molecular comparison of monocot and dicot U1 and U2 snRNAs
Authors: Musci Michael A. , Egeland Daniel B. , Schuler Mary A.
Published: March 2003

To elucidate differences between the pre‐mRNA splicing components in monocots and dicots, we have cloned and characterized several U1 and U2 snRNA sequence variants expressed in wheat seedling nuclei. Primer extension sequencing on wheat and pea snRNA populations has demonstrated that two 5′‐ terminal nucleotides found in most other U1 snRNAs are missing/modified in many plant U1 snRNAs. Comparison of the wheat U1 and U2 snRNA variants with their counterparts expressed in pea nuclei has defined regions of structural divergence between monocot and dicot U1 and U2 snRNAs. The U1 and U2 snRNA sequences involved in RNA:RNA interaction with pre‐mRNAs are absolutely conserved. Significant differences occur between wheat and pea U1 snRNAs in stem I and II structures implicated in the binding of U1‐specific proteins suggesting that the monocot and dicot U1‐specific snRNP proteins differ in their binding specificities. Stem III structures, which are required in mammalian systems for splicing complex formation but not for U1‐specific protein binding, differ more extensively than stems I, II, or IV. In U2 snRNAs, the sequence differences between these two species are primarily localized in stem III and in stem IV which has been implicated in snRNP protein binding. These differences suggest that monocot and dicot U1 and U2 snRNPs represent distinct entities that may have monocot‐ and dicot‐specific snRNP protein variants associated with each snRNA.
Specificity of a promoter from the rice tungro bacilliform virus for expression in phloem tissues
Authors: Bhattacharyya‐Pakrasi Maitrayee , Peng Jianying , Elmer J. Scott , Laco Gary , Shen Ping , Kaniewska Maria B. , Kononowicz Halina , Wen Fujiang , Hodges Thomas K. , Beachy Roger N.
Published: March 2003

The major promoter region for the transcription of the genome of rice tungro bacilliform virus (RTBV), a newly described badnavirus, has been identified. Fragments of the RTBV genome upstream of the site of transcription initiation were isolated and tested for promoter activity using a β‐glucuronidase reporter gene (gusA). Assays of transient gusA expression were performed following introduction of the chimeric gene into protoplasts via electroporation. The chimeric RTBV‐promoter:gusA gene was more active in rice protoplasts than in maize or tobacco protoplasts, but was weaker than gusA controlled by an enhanced 35S promoter from cauliflower mosaic virus. Analysis of gusA gene expression following introduction of chimeric reporter genes into intact leaves via micro‐projectile bombardment indicated that the GUS activity is present primarily in vascular tissues. Transgenic rice plants carrying the chimeric gusA gene had GUS activity only in the phloem of the vascular bundles in the leaf. Tissue printing studies demonstrated that RTBV accumulates in the vascular bundles of infected rice leaves. The results of our study indicate that phloem‐specific expression from the RTBV promoter is an intrinsic property of the viral promoter.
Petal and stamen formation in petunia is regulated by the homeotic gene fbp1
Authors: Angenent Gerco C. , Franken John , Busscher Marco , Colombo Lucia , van Tunen Arjen J.
Published: March 2003

For Arabidopsis and Antirrhinum, the so‐called ABC model has been developed, which postulates that the determination of floral organ primordia is controlled by the action of three classes of homeotic genes. A number of these ABC genes encode putative transcription factors with the MADS box DNA binding motif. This paper reports on the functional analysis of the petunia MADS box gene fbp1. The temporal and spatial expression of fbp1 has been investigated in detail in transgenic plants containing the β‐glucuronidase (GUS) reporter gene fused to an fbp1 promoter fragment. fbp1‐driven GUS activity was specifically detected in emerging petal and stamen primordia, suggesting a function of fbp1 in the control of second and third floral whorl identity. To test this hypothesis, transgenic petunia plants were generated in which fbp1 expression was inhibited by a co‐suppression approach. The flowers of such plants exhibited homeotic conversions of petals towards sepals and stamens towards carpels. Occasionally, the third whorl carpels are fused forming a pentalocular gynoecium. This dominant fbp1 mutation acted as a single Mendelian trait in genetic crosses. These results strongly indicate that fbp1 is a petunia class B homeotic gene which is required for the correct initiation and determination of petals and stamens.
The profilin multigene family of maize: differential expression of three isoforms
Authors: Staiger Christopher J. , Goodbody Kim C. , Hussey Patrick J. , Valenta Rudolf , Drøbak Bjørn K. , Lloyd Clive W.
Published: March 2003

Profilin is a small (12–15 kDa) actin‐ and phospholipid‐binding protein previously known only from studies on animals and lower eukaryotes but recently identified as a birch pollen allergen. Here we have identified and characterized three members of the profilin multigene family from the plant Zea mays. Two cDNAs isolated from a maize pollen library (ZmPRO 1 and ZmPRO 3) each have a single, large open reading frame encoding a putative polypeptide 131 amino acids long with a predicted molecular weight of approximately 14 kDa. A third maize pollen cDNA (ZmPRO 2) has two in‐frame translation initiation codons. Use of the first ATG would result in a polypeptide 137 amino acids long with a molecular weight of 14.8 kDa. The three maize profilins are highly homologous to each other (>90% nucleotide and amino acid sequence identity) as well as other plant profilins but show far less similarity (30–40% amino acid sequence identity) to animal and lower eukaryote profilins. Multiple sequence alignments indicate that only nine residues are shared by all eukaryotic profilins examined. However, limited comparisons reveal domains in the NH2 and COOH termini that have a high degree of similarity suggesting functional conservation. The maize gene family size is estimated to contain three to six members based on Southern blot experiments with gene‐specific and coding region probes. Northern blot analysis demonstrates that the three maize profilin cDNAs characterized here are utilized in a tissue‐specific manner and are anther or pollen specific.
Recombinant inbred lines for mapping RFLP and phenotypic markers in Arabidopsis thaliana
Authors: Lister Clare , Dean Caroline
Published: March 2003

Recombinant inbred (RI) lines of Arabidopsis thaliana (Arabidopsis) have been generated from a cross between the ecotypes Landsberg erecta and Columbia. Progeny of 300 individual F2 seedlings were taken by single seed descent to the F8 generation. Sixty‐seven loci, scored using 64 RFLP probes and one phenotypic marker, chosen at approximately 20 cM intervals from the two previously published RFLP maps, were mapped using 100 of these RI lines. More than 500 other new loci are currently being mapped using these RI lines by several other groups. These 100 RI lines thus provide the material to map new probes or phenotypic traits polymorphic between Landsberg erecta and Columbia, relative to an increasing number of molecular markers. Higher resolution mapping of distinct chromosomal regions can be achieved by analysing the segregation of particular markers on the additional 200 RI lines.
Molecular cloning and expression patterns of three alleles of the Deficiens‐homologous gene St‐Deficiens from Solanum tuberosum
Authors: Garcia‐Maroto Federico , Salamini Francesco , Rohde Wolfgang
Published: March 2003

Three alleles of the Deficiens‐homologous potato gene St‐Deficiens (St‐Def) present in the genome of a tetraploid Solanum tuberosum variety were isolated and characterized. For one allele (St‐Def pD13) the complete molecular structure was determined by sequence analysis and comparison with its cDNA, while for the other two alleles (pD10, pD12) only partial sequences of regulatory and coding regions were obtained. All three alleles showed (except for one amino acid exchange in pD10) identical sequences in the coding region. While sequence variation was observed within the respective promoters starting some 300 nt upstream of the putative transcriptional start site, the 3′ terminal promoter sequences were highly conserved. Within this region, a sequence of 81 nt was identified which showed 73% sequence identity to a corresponding sequence in the Deficiens promoter. This region which contains a putative serum response element was previously shown to regulate the expression of the Deficiens gene in Antirrhinum majus. Expression patterns for the three alleles in transgenic potato lines expressing St‐Def promoter/Gus constructs were identical. GUS activity was predominantly located in petals and stamens as expected for the activity of a Def‐homologous gene, but a significant level of expression was also detected in the ovary wall and in the vascular bundles supporting anthers and petals. The promoters were also active in abscission structures at the junction of flower stem and pedicel, as well as in anther stomium.
A role for γ3 hordein in the transport and targeting of prolamin polypeptides to the vacuole of developing barley endosperm
Authors: Rechinger K.B. , Simpson D.J. , Svendsen I. , Cameron‐Mills V.
Published: March 2003

Hordein synthesis, transport and deposition was analysed by immunocytochemistry in developing endosperm cells of wild‐type (Carlsberg II) and mutant varieties deficient in B hordein (hor2ca), γ1 hordein (Donetsky), γ2 hordein and minor B hordein polypeptides (Haisa), or γ3 hordein (Nevsky). In all varieties, hordein polypeptides were detected both in the cytoplasm as globules, ranging in diameter from 50 nm to 1.24 µm, and in the vacuole as protein bodies. In the cytoplasmic globules B and C hordein polypeptides are assembled as a core and are surrounded by an outer layer of γ1 and γ2 hordein. The globules apparently fuse several times in the cytoplasm before entering the vacuole. Absence of γ3 hordein in the mutant Nevsky leads to a dramatic change in hordein polypeptide targeting, the hordein storage proteins being largely deposited in the lumen of the rough endoplasmic reticulum. γ3 Hordein is unique among the sulphur‐rich hordein polypeptides, being monomeric and forming only intramolecular disulphide bridges, while the other B and γ hordein polypeptides are aggregated by intermolecular disulphide bridges. Retention of hordein in the rough endoplasmatic reticulum in the absence of γ3 hordein suggests that γ3 hordein may maintain the prolamin storage polypeptides in a transport competent state. The sequence of the mature γ3 hordein polypeptide was deduced from a cDNA clone, and compared with γ2 hordein. The epitope recognized by the γ1 + γ2 hordein‐specific BX monoclonal antibody used for immunocytochemistry was mapped to include E190 and K193, by synthesizing overlapping oligopeptides.
A dysfunctional movement protein of tobacco mosaic virus that partially modifies the plasmodesmata and limits virus spread in transgenic plants
Authors: Lapidot Moshe , Gafny Ron , Ding Biao , Wolf Shmuel , Lucas William J. , Beachy Roger N.
Published: March 2003

A chimeric gene encoding a dysfunctional tobacco mosaic virus (TMV) movement protein (MP) mutant lacking amino acids 3, 4 and 5 (MPΔ3–5), was expressed in transgenic Nicotiana tabacum Xanthi and Xanthi NN plants. Immunogold labeling studies of tissues from transgenic plants indicated that while wild‐type MP accumulated in the plasmodesmata, MPΔ3–5 did not. Tissue fractionation studies confirmed that only a low level of the mutant MP accumulated in the cell wall‐enriched fraction compared with the accumulation of the wild‐type MP. Dye coupling studies showed that MPΔ3–5 enabled the movement between leaf mesophyll cells of a fluorescently labeled dextran of 3 kDa, while 9.4 kDa molecules failed to move. In contrast, in transgenic plants expressing the wild‐type MP gene the 9.4 kDa probe did move from cell to cell. Seedlings from self‐fertilized transgenic plants were inoculated with TMV and observed for disease symptoms. Transgenic Xanthi NN plants that expressed the MPΔ3–5 gene developed fewer and smaller necrotic local lesions compared with control plants following inoculation with TMV. Transgenic Xanthi nn plants were delayed in the development of systemic symptoms. Inoculating the transgenic plants with TMV‐RNA, and the tobamo‐viruses TMGMV and SHMV, essentially produced the same results, i.e. inhibition of disease development. These results demonstrate that transgenic plants expressing an inactive MP can inhibit virus disease spread presumably by interfering with its cell‐to‐cell movement.
Identification of photo‐inactive phytochrome A in etiolated seedlings and photo‐active phytochrome B in green leaves of the aurea mutant of tomato
Authors: Sharma Rameshwar , López‐Juez Enrique , Nagatani Akira , Furuya Masaki
Published: March 2003

The contents of spectrophotometrically measurable phytochrome A (PhyA) and phytochrome B (PhyB) and the corresponding immunochemically detectable apoproteins (PHYA and PHYB) were examined in dark‐ and light‐grown tissues of the aurea mutant of tomato and its wild‐type (WT). The amount of PHYA in etiolated aurea seedlings was found to be about 20% of that in the WT; this PHYA showed no photoreversible changes in absorbance, no downregulation of the level of PHYA in light‐grown seedlings, and no differential proteolysis of Pr and Pfr species in vitro which was seen in the case of the WT. By contrast, the amount of PHYB in aurea seedlings was not significantly different from that in WT seedlings. Phytochrome isolated from green leaves of the aurea mutant and purified by ion‐exchange chromatography showed a red/far‐red reversible spectral change, and its elution profile during chromatography was essentially similar to that of PHYB. The results indicate that aurea is a mutant that is deficient in photoactive PhyA at the etiolated stage, when it contains a spectrally inactive PHYA. However, the mutant contains spectrally active PhyB in its green tissue as does the WT.
PCR‐amplified microsatellites as markers in plant genetics
Authors: Morgante M. , Olivieri A.M.
Published: March 2003

In order to assess the feasibility of using microsatellites as markers in plant genetics, a survey of published DNA sequence data for presence, abundance and ubiquity in higher plants of all types of dinucleotide and trinucleotide repeats with a minimum number of 10 and 7 units, respectively, was conducted. This search revealed that such microsatellites are frequent and widely distributed; they were uncovered in 34 species, with a frequency of one every 50 kb. AT repeats were by far the most frequently observed class of dinucleotide microsatellites, whereas AC/TG repeats, which are common in animals, were observed only once. TAT repeats prevailed among trinucleotides. Polymerase chain reaction amplification of (AT)n and (TAT)n micro‐satellites in soybean (Glycine max (L.) Merr.) revealed that they are highly polymorphic, as a consequence of length variation, somatically stable and inherited in a co‐dominant Mendelian manner. The abundance and amount of information derived from such markers, together with the ease by which they can be identified, make them ideal markers for plant genetic linkage and physical mapping, population studies and varietal identification.
Genetic control of dihydroflavonol 4‐reductase gene expression in Petunia hybrida
Authors: Huits Henk S.M. , Gerats Anton G.M. , Kreike Marja M. , Mol Joseph N.M. , Koes Ronald E.
Published: March 2003

The functions of four loci (An1, An2, An4, and An6) which control pigmentation in flowers of Petunia hybrida have been characterized. Linkage‐analysis and molecular complementation experiments showed that the An6 locus contains the structural dfrA gene, encoding the enzyme dihydroflavonol 4‐reductase (DFR). Analysis of gus gene expression driven by the dfrA promoter in transgenic plants showed that the dfrA promoter is highly active in the flower corolla, the anthers and seeds and, at a lower level, in ovules and the flower stem. These data are discussed in relation to the expression of other pigmentation genes and the accumulation pattern of anthocyanins. The expression of the dfrA‐gus transgene was dependent on the genes an1 (in every tissue), an2 (in the flower limb only) and an4 (in anthers), demonstrating that these genes encode regulatory factors that control dfrA promoter activity.
Synthesis of a bifunctional metallothionein/β‐glucuronidase fusion protein in transgenic tobacco plants as a means of reducing leaf cadmium levels
Authors: Elmayan Taline , Tepfer Mark
Published: March 2003

Chimeric genes under the control of a CaMV 35S promoter with a doubled enhancer (35S2) that encode a mammalian metallothionein (hMTII), or an Escherichia coliβ‐glucuronidase (GUS), or a hMTII/GUS fusion protein were introduced into the genome of tobacco (Nicotiana tabacum cv. PBD6). Transcripts and Cd‐binding proteins of expected size were observed in plants expressing either the 35S2‐hMTII or the 35S2hMTII/GUS gene, and in the latter plants a protein with GUS activity that was larger than the native GUS enzyme was observed. Thus, plants expressing the hMTII‐GUS gene synthesize a bifunctional protein, with both GUS and Cd‐binding activity. In an in vitro assay, seedlings expressing either one of these genes had 60–70% lower Cd concentration in their shoots than controls, and Cd translocation to the shoot system was reduced (∼20% of Cd absorbed was translocated), compared with that in controls expressing a 35S2‐GUS gene, where ∼50% of the Cd absorbed was translocated.
An Arabidopsis thaliana RFLP mapping set to localize mutations to chromosomal regions
Authors: Fabri Christoph O. , Schäffner Anton R.
Published: March 2003

Mapping of newly identified Arabidopsis thaliana mutants is an important step towards their molecular characterization and the attempt to saturate the genome by known mutations. The classical genetic analysis using phenotypic tester lines is well‐established, but laborious, time‐consuming and potentially ambiguous. An alternative molecular strategy was developed that is based on RFLPs. Subcloned DNA markers that detect only segregating RFLP bands distinguishing A. thaliana ecotype Landsberg from Columbia or Enkheim after EcoRI restriction digestion compose an Arabidopsis RFLP mapping set (ARMS). Up to 13 markers uniformly cover the five A. thaliana chromosomes and can be scored in only two successive Southern experiments on a single blot without mutual interference of the signals. Thus, this system allows a simple, reliable, rapid and especially inexpensive mapping of any monogenic mutant locus to the A. thaliana chromosomes. Several loci can be analysed in one experiment if the respective blots are hybridized together. This paper demonstrates the mapping of two recessive mutants affecting the development of A. thaliana leaves which had been generated in the Columbia and Enkheim ecotype by analysing less than 20 F2 individuals. Further markers to refine or verify the result on the same blot can be chosen out of 14 additional probes detecting single segregating EcoRI polymorphic bands as well.
Correlation between the activities of five ribosome‐inactivating proteins in depurination of tobacco ribosomes and inhibition of tobacco mosaic virus infection
Authors: Taylor Sally , Massiah Andrea , Lomonossoff George , Roberts Lynne M. , Lord J. Michael , Hartley Martin
Published: March 2003

The rRNA depurination activities of five ribosome‐inactivating proteins (RIPs) were compared in vitro using yeast and tobacco leaf ribosomes as substrates. All of the RIPs (pokeweed antiviral protein (PAP), dianthin 32, tritin, barley RIP and ricin A‐chain) were active on yeast ribosomes. PAP and dianthin 32 were highly active and ricin A‐chain weakly active on tobacco ribosomes, whereas tritin and barley RIP were inactive. PAP and dianthin 32 were highly effective in inhibiting the formation of local lesions caused by tobacco mosaic virus (TMV) on tobacco leaves, whereas tritin, barley RIP and ricin A‐chain were ineffective. The apparent anomaly between the in vitro rRNA depurination activity, but lack of antiviral activity of ricin A‐chain was further investigated by assaying for rRNA depurination in situ following the topical application of the RIP to leaves. No activity was detected, a finding consistent with the apparent lack of antiviral activity of this RIP. Thus, it is concluded that there is a positive correlation between RIP‐catalysed depurination of tobacco ribosomes and antiviral activity which gives strong support to the hypothesis that the antiviral activity of RIPs works through ribosome inactivation.