bluuebunny/crossref_metadata_2025_split huggingface dataset:
Xylem sap flow of Norway spruce after inoculation with the blue‐stain fungus Ceratocystis polonica
Authors: Kirisits T. , Offenthaler I. 
Published: March 2003

In a field experiment, the sap flow of Norway spruce (Picea abies) was measured in response to inoculation with Ceratocystis polonica, a virulent fungal associate of the spruce bark beetle Ips typographus. Four vigorous, mature Norway spruce trees were mass‐inoculated with C. polonica at a density of four inoculations per dm2 within a 120‐cm‐wide band on the lower bole. Two other trees were inoculated with sterile agar and served as controls. Sap flow of the six trees was measured by the thermal dissipation method from three weeks prior to inoculation until five months after inoculation. In three trees that had been inoculated with the fungus, sap flow density decreased dramatically within the first weeks after inoculation until no sap flow was measurable 4–6 weeks after inoculation. No marked changes in sap flow density were recorded in the fourth tree that had been inoculated with C. polonica, and this tree survived the inoculation. Inoculation with sterile agar did not have any apparent influence on the sap flow of the control trees. The results confirm the ability of C. polonica to kill mature Norway spruce trees. Sap flow measurements by the thermal dissipation method provided a direct and nondestructive method for monitoring the effects of fungal infection on sapwood functionality. Its application for further studies on vascular wilt and vascular stain diseases of trees is therefore recommended.
Downregulation of mafB Expression in T‐Helper Cells During Early Differentiation In Vitro
Authors: Hashizume H. , Hamalainen H. , Sun Q. , Sucharczuk A. , Lahesmaa R. 
Published: March 2003

AbstractWe have studied the expression of a human homologue of mafB (maf‐1), a member of the family of large maf transcription factors. In support of the suggested key role that mafB expression plays in differentiating macrophages, we found mafB to be expressed at a very high level in monocytic U937 and THP‐1 cell lines. However, we show here that mafB transcription is not restricted to myeloid cells but can also be detected in lymphoid cells, indicating transcriptional plasticity during haematopoiesis. In conclusion, strong proliferative signals mediated by T‐cell activation and interleukins (IL‐4 and IL‐12) downregulate the mafB messenger RNA transcript level when resting naïve CD4+ T‐helper cells enter the differentiation pathway in vitro.
DNA identification of museum specimens of the Anopheles gambiae complex: an evaluation of PCR as a tool for resolving the formal taxonomy of sibling species complexes
Authors: Townson Harold , Harbach Ralph E. , Callan Tara A. 
Published: March 2003

SummarySpecies‐specific rDNA primers were tested for their ability to identify museum specimens of the Anopheles gambiae complex ranging in age from 15 to 93 years. Twenty pinned females of known or inferred identity were selected for study from the collection of The Natural History Museum in London, primarily on grounds of their provenance and/or presumed identity. The abdomens were removed and provided ‘blind’ to the first author for identification. Most of the specimens (17/20) yielded amplifiable DNA and sixteen were identified to species, fifteen unambiguously. The PCR identifications of twelve specimens matched identifications on museum labels, including seven of unambiguous identity. One of the specimens identified correctly was a 93‐year‐old syntype of An. gambiae. This study demonstrates that PCR‐based methods, by establishing the genetic identity of name‐bearing type specimens in museum collections, may help in the application of available names to members of sibling species complexes.
A fossil nymphomyiid (Diptera) from the Baltic and Bitterfeld amber
Authors: Wagner R. , Hoffeins C. , Hoffeins H. W. 
Published: March 2003

Summary Nymphomyia succina sp.n., the first fossil nymphomyiid fly (Diptera) from the Eocene Baltic and Bitterfeld amber is described and figured, based on four males. A probably conspecific female from the Baltic amber is also described and figured. With the discovery of this species, a gap in the distribution pattern of extant Nymphomyiidae is closed. It is probable that nymphomyiids colonized the eastern Nearctic Region via the Thule landbridge approximately 25–30 million years before present.
Phylogeny of Oestridae (Insecta: Diptera)
Authors: Pape Thomas 
Published: March 2003

SummaryThe phylogeny of Oestridae was analysed at the generic level using 118 characters from all developmental stages and including morphology, ontogeny, physiology and behaviour. Four major clades were given subfamilial rank with the phylogenetic relationship (Cuterebrinae (Gasterophilinae (Hypodermatinae + Oestrinae))). The subdermal parasites of the African elephant, Neocuterebra squamosa Grünberg and Ruttenia loxodontis Rodhain, had their most probable affiliation subordinate to the clade of stomach parasites, although their exact position needs further investigation. Genus Ochotonia Grunin, which is known from a single third‐instar larva only, was the probable sister group of all other Hypodermatinae. Twenty‐five oestrid genera were recognised as valid and those containing more than one species were defined through lists of autapomorphies. Cuterebra Clark was proposed as a senior synonym of Alouattamyia Townsend, Andinocuterebra Guimarães, Pseudogametes Bischof and Rogenhofera Brauer. The clade of hypodermatine ungulate parasites (Hypoderma Latreille +Pallasiomyia Rubtzov +Pavlovskiata Grunin +Przhevalskiana Grunin +Strobiloestrus Brauer) remained largely unresolved, and genus Przhevalskiana emerged without defining characters.
Negative and positive regulation of a novel proline‐rich protein mRNA by fungal elicitor and wounding.
Authors: Sheng J , D'Ovidio R , Mehdy MC 
Published: March 2003

SummaryThe structure and expression of a cDNA clone (PvPRP1) isolated from a cDNA library prepared from bean (Phaseolus vulgaris) cells treated with fungal elicitor have been characterized. Sequence analysis of the 1.1 kb insert revealed a complete open reading frame which encodes a 32 kDa protein. The protein resembles other proline‐rich proteins in plants but possesses several unique features: (i) the N‐terminal half of the protein is proline rich and contains three identical repeats of Pro‐Val‐ His‐Pro‐Pro‐Val‐Lys‐Pro‐Pro‐Val and six related repeats; (ii) the proline‐rich region contains two tracts of six histidine residues; and (iii) the C‐terminal half is low in proline and lacks repeats. Genomic blotting experiments suggest the presence of a single PvPRP1 gene as well as more distantly related genes within the bean genome. A dramatic decrease in PvPRP1 mRNA levels occurs within 2 h of elicitor treatment of cell cultures. The PvPRP1 mRNA is present at a moderate level in hypocotyls. Upon wounding, the mRNA level initially decreases over 5 h and then accumulates over 25 h to levels which are higher than the basal level in unwounded hypocotyls. Based on the similarity to other proline‐rich proteins with repeated motifs, including the presence of a putative signal peptide, it is likely that the PvPRP1 protein is targetted to the cell wall. The expression of the PvPRP1 gene appears to be integrated with the remodeling of the plant cell wall during the defense response.
Construction and expression of nonsense suppressor tRNAs which function in plant cells
Authors: Franklin Scott , Lin Tsai Yun , Folk William R. 
Published: March 2003

SummaryAn Arabidopsis thaliana L. DNA containing the tRNATrpUGG gene was isolated and altered to encode the amber suppressor tRNATrpUAG or the ochre suppressor tRNATrpUAA. These DNAs were electroporated into carrot protoplasts and tRNA expression was demonstrated by the translational suppression of amber and ochre nonsense mutations in the chloramphenicol acetyltransferase (CAT) reporter gene. DNAs encoding tRNATrpUAG and tRNATrpUAA nonsense suppressor tRNAs caused suppression of their cognate nonsense codons in CAT mRNAs, with the tRNATrpUAG gene exhibiting the greater suppression under optimal conditions for expression of CAT. The development of these translational suppressors which function in plant cells facilitates the study of plant tRNA gene expression and will make possible the manipulation of plant protein structure and function.
A gibberellin‐regulated gene from wheat with sequence homology to cathepsin B of mammalian cells
Authors: Cejudo Francisco J. , Murphy George , Chinoy Catherine , Baulcombe David C. 
Published: March 2003

SummaryA previous report described several cDNAs corresponding to mRNAs which accumulated in wheat aleurone layers treated with gibberellic acid (GA) (Baulcombe and Buffard, 1983). The protein sequence deduced from one of these clones (2529) has extensive similarity to the thiol protease, cathepsin B from mammalian cells. Southern analysis of wheat DNA has shown that the 2529 mRNA is encoded by a small family of genes carried on the group 4 chromosome. The nucleotide sequence of a member of the gene family expressed at a low level in aleurone layers and the use of a primer extension assay to identify a clone of a member of the gene family producing an abundant mRNA are reported. The 2529 mRNA accumulates in the scutellum and the aleurone layer of germinating grains where its expression is regulated by GA. In the scutellum the expression was restricted to the parenchyma, suggesting that the 2529 product may have a role other than for mobilization of the endosperm.
The root‐knot nematode resistance gene (Mi) in tomato: construction of a molecular linkage map and identification of dominant cDNA markers in resistant genotypes
Authors: Ho Jeong‐Yau , Weide Rob , Ma Helen M. , van Wordragen Monique F. , Lambert Kris N. , Koornneef Maarten , Zabel Pim , Williamson Valerie M. 
Published: March 2003

SummaryA dominant allele at the Mi locus on chromosome 6 of tomato (Lycopersicon esculentum Mill) confers resistance to three species of root‐knot nematodes (Meloidogyne). The resistance, which is associated with a localized necrotic response, was originally introduced into tomato from the wild species Lycopersicon peruvianum. As a step towards the molecular cloning of Mi, we have identified closely linked DNA markers from both cDNA and genomic DNA libraries as restriction fragment length polymorphisms (RFLPs). DNA from tomato populations segregating for nematode resistance was analyzed to generate a highresolution genetic map of this region. Additional information on gene order was obtained by comparing the size of the introgressed L. peruvianum chromosomal segment within a collection of nematode‐resistant tomato lines. Among the four cDNA markers that are tightly linked to Mi, three are dominant, i.e. L. peruvianum‐specific. One cDNA marker corresponds to a gene family comprising 20–30 members, one of which is diagnostic for all nematode‐resistant genotypes tested. The presence of non‐homologous sequences around the Mi gene may contribute to the suppression of recombination in this region of the genome in crosses heterozygous for Mi. The potential of ‘walking’ from closely linked markers to Mi is discussed.
Light‐regulated and endogenous fluctuations of chloroplast transcript levels in Chlamydomonas. Regulation by transcription and RNA degradation
Authors: Salvador Maria L. , Klein Uwe , Bogorad Lawrence 
Published: March 2003

SummaryChanges in the relative sizes of pools of transcripts of organelle genes during plastid development are common in flowering plants, but technical difficulties have prevented direct determinations of the effects of changes in rates of transcription and degradation on such fluctuations. It has been possible to follow both rates in Chlamydomonas reinhardtii. In synchronous or asynchronous cultures of cells grown in 12 h light/12 h dark periods, sizes of pools of transcripts of the chloroplast genes atpA, atpB, tufA, and psaB fluctuate. Differences in chloroplast transcript abundances in light/dark cycles were found to be cell cycle‐independent but controlled by either an endogenous rhythm (atpA, atpB, and tufA) or by light (psaB). In vivo labeling experiments showed that transcriptional regulation and light/dark‐regulated degradation both contribute, in gene‐specific manners, to the level of transcripts of individual C. reinhardtii chloroplast genes in cells grown in alternating light/dark cycles.
Transposition of the maize Ds element from a viral vector to the rice genome
Authors: Sugimoto Kazuhiko , Otsuki Yoshiaki , Saji Shoko , Hirochika Hirohiko 
Published: March 2003

SummaryThe geminivirus miscanthus streak virus (MiSV) was used as a gene vector to study the transposition of the maize Ds element in rice protoplasts. Efficient excision of the Ds from the MISV vector was observed only when the MiSV vector was allowed to replicate and the plasmid expressing the transposase gene encoded by Ac was co‐transfected. Under the same condition, the Ds carrying a hygromycin phosphotransferase gene (Ds::HPT) was also efficiently excised. Hygromycin‐resistant calli were obtained by culturing these transfected protoplasts in order to examine the transposition of the excised Ds::HPT into the rice genome. In five out of 16 calli examined, the Ds::HPT, but not the vector sequence, was integrated into the rice genome and 8 bp target site duplication typical of Ac/Ds transposition was generated. These results show that the Ds::HPT inserted in the MISV vector transposed directly into the rice genome. This demonstrates the direct transposition of a cloned plant transposable element into the plant genome. Implications of these finding are discussed.
Synergism between CACGTG (G‐box) and CACCTG cis‐elements is required for activation of the bean seed storage protein β‐phaseolin} gene†
Authors: Kawagoe Yasushi , Campell Bruce R. , Murai Norimoto 
Published: March 2003

SummaryExpression of bean seed storage protein phaseolin is under strict developmental control. Four distinct nuclear proteins recognize in vitro the proximal, β‐phaseolin} promoter (−295/+45) which confers spatial and temporal regulation of the native gene. Functional significance of these protein‐binding sites was evaluated by substitution mutation of the motifs in the promoter, which was fused to GUS reporter gene, and subsequent transient gene expression assay using protoplasts from developing bean cotyledons. DNA‐binding protein CAN binds three CANNTG motifs, CACGTG (−248/−243), CACCTG (−163/−158), and CATATG (−100/−95). Substitution mutation of the CACGTG motif, which is commonly known as G‐box, reduced the −295 promoter activity by 75%, indicating that the G‐box is a major positive cis‐element. Mutation analyses also demonstrated that the CACCTG and CATATG motifs act as positive and negative cis‐elements, respectively. Substitution mutation of all three CANNTG motifs essentially eliminated the −295 promoter activity. A construct containing the G‐box and CACCTG motif resulted in a transcriptional level that is much greater than the sum of the transcriptional levels from the individual cis‐elements, demonstrating that the G‐box and CACCTG act synergistically. Substitution mutations of two AT‐rich sequences, to which a nuclear protein AG‐1 binds, showed that these sites function as major negative (−376/−367, −356/−347) or positive (−191/−182) cis‐elements, and that the effect of the two AG‐1 binding sites was counteractive in the −391 promoter. These results indicate that the three CANNTG motifs and two AG‐1‐binding sites play critical roles in transcription of the {β‐phaseolin} gene in cotyledons.
Cell‐cycle regulation of hydroxyproline‐rich glycoprotein HRGPnt3 gene expression during the initiation of lateral root meristems
Authors: Vera Pablo , Lamb Chris , Doerner Peter W. 
Published: March 2003

SummaryAnalysis of transgenic tobacco plants containing a tobacco hydroxyproline‐rich glycoprotein HRGPnt3 gene promoter‐β‐glucuronidase (GUS) gene fusion (HRGPnt3‐uidA) showed that this promoter is active not only in the early stages of initiation of lateral roots as previously described, but also in the initiation of adventitious roots, with similar selective expression in a subset of pericycle cells. HRGPnt3 is also induced during initiation of hairy roots following transformation by Agrobacterium rhizogenes. The auxin indole acetic acid (IAA) induces an increase in the number of characteristic discrete sites of HRGP‐nt3 expression. It is shown that these sites are destined to form new root primordia from pericycle cells of both adventitious and main roots. Dose‐dependent induction of root meristems by auxin overcomes the limitations of this naturally stochastic process and makes lateral root initiation amenable to biochemical analysis. Quiescent pericycle cells, which are developmentally arrested in the G2 phase of the cell cycle, rapidly progress into M phase upon mitogenic stimulation. Colchicine and nocodazole, which block completion of mitosis, inhibited the activation of the HRGPnt3 promoter but did not block auxin induction of parA, a marker for de‐differentiation in leaf mesophyll cell‐derived protoplasts. Hydroxyurea, which inhibits cell‐cycle progression at the G1/S‐phase transition and also blocks lateral root initiation, did not inhibit HRGPnt3 induction. Thus, HRGPnt3 induction precedes completion of the first cell division during primordium formation, and is one of the initial steps in a sequential program of gene expression activated upon stimulation of cell division for the development of a new meristem during lateral root initiation.
Comparison of the effects of N6‐methyldeoxyadenosine and N5‐methyldeoxycytosine on transcription from nuclear gene promoters in barley
Authors: Rogers John C. , Rogers Sally W. 
Published: March 2003

SummaryMethylation of deoxycytosine residues in plant nuclear DNA at CpG dinucleotides is generally assumed to suppress transcription, while deoxyadenosine methylation on recombinant reporter gene constructs transiently introduced into plant cells increases expression by uncharacterized mechanisms. A particle bombardment transient expression system was used in intact barley aleurone layers to quantitate the effects of CpG and A methylation on transcription from well‐characterized hormone‐regulated α‐amylase promoters. Methylation of C in all CpG pairs had little effect on transcription. In contrast, the presence of methylated A residues in the sequence GATC scattered in the reporter plasmid outside of the promoter increased transcription two‐ to fivefold, regardless of the strength of the promoter, and proper hormonal regulation of transcription was maintained. The methyl‐dA effect was similar when the amount of reporter construct DNA used was varied over a 20‐fold range, beginning with an amount that gave only a small increment of expression above background. Similar enhancing effects for methyl‐dA were seen with the CaMV 35S, maize Adh1, and maize ubiquitin promoters, though the magnitude varied for each individual promoter. Methyl‐dA did not detectably affect plasmid DNA stability in aleurone cells in transient expression experiments because the enhancing effect of methyl‐dA on expression was the same regardless of whether the assay was performed at 12 h or 40 h. Several proteins in wheat germ nuclear extracts bound preferentially to methylated DNA as assessed by gel retardation assays; one showed preferential binding to methyl‐dA rather than methyl‐CpG residues. The data indicate that the presence of methyl‐dA in the vicinity of active promoters enhances transcription of nuclear genes in barley in a manner independent of the strength of the promoter. This effect may be mediated by a methyl‐dA‐binding protein.
Sequence‐based identification of T‐DNA insertion mutations in Arabidopsis: actin mutants act2‐1 and act4‐1
Authors: McKinney Elizabeth C. , Ali Nazeem , Traut Alice , Feldmann Kenneth A. , Belostotsky Dmitry A. , McDowell John M. , Meagher Richard B. 
Published: March 2003

SummaryA method is presented to facilitate the isolation of mutations in plant genes, which requires knowledge of the target gene or protein sequence, and is independent of mutant phenotype. The polymerase chain reaction was used to amplify the junctions between a T‐DNA insert and the gene of interest from pools of mutant plant lines. The approach was used to identify mutations in Arabidopsis thaliana actin genes. The Arabidopsis genome encodes 10 actins in six ancient subclasses each with distinct expression patterns. Primers in the T‐DNA border and highly degenerate actin primers, designed from conserved amino acid motifs, were used to prime the amplification. The PCR products were transferred to filters and probed for actin at low stringency. Thus, mutations in all 10 actin genes were screened for simultaneously. Mutations in the vegetative constitutive actin gene, ACT2, and the pollen‐specific actin gene, ACT4, were identified in a population of 5300 lines containing approximately 1.5 T‐DNA insertions per line. The screen was sensitive enough that actin insertion alleles were easily distinguished among pools of 100 plant lines. PCR techniques were used which accelerated the purification of mutant lines, and segregation, physical mapping, and sequencing of the act2‐1 and act4‐1 mutations. This strategy should be generally useful in screening mutant libraries made with a variety of plant insertion elements for mutations in any known sequence.
Identification of a membrane glycoprotein in pollen of Papaver rhoeas which binds stigmatic self‐incompatibility (S‐) proteins
Authors: Hearn Melanie J. , Franklin F. Christopher H. , Ride Jon P. 
Published: March 2003

Recombinant stigmatic self‐incompatibility (S‐) proteins from Papaver rhoeas have previously been shown to be biologically functional, inhibiting only pollen of the same S‐genotype. In an attempt to identify molecules in pollen which interact with these proteins, Western ligand blotting was used, with the recombinant S‐proteins as probes followed by immunodetection of the bound S‐protein. This revealed that pollen of all S‐genotypes tested contained a 70–120 kDa protein which bound the S1, S3 and S8 proteins in an indistinguishable manner. Binding was destroyed by pretreatment of blots with periodate, implicating a glycoprotein with activity being dependent on the glycan moiety. The activity completely partitioned into the detergent phase on condensation with Triton X‐114, indicating an integral membrane protein. On aqueous two‐phase partition of microsomal membrane preparations, the majority of the binding activity partitioned into the upper phase, suggesting that the molecule is located in the plasma membrane.No equivalent binding could be detected in extracts of leaves, stems, roots or stigmas of P. rhoeas, nor in immature anthers. Identical activity was detected in pollen of some other Papaver species, but not in pollen of Brassica oleracea, Nicotiana tabacum or Petunia hybrida. The presence in mature pollen of P. rhoeas of a plasma membrane glycoprotein which binds S‐proteins from the stigma of the same species, albeit in a non S‐allele‐specific manner, strongly suggests that this molecule has a role somewhere in the interaction of the stigma proteins with pollen. The activity is not that expected of an S‐specific receptor, but by analogy with certain mammalian systems the molecule may act as an accessory receptor, or co‐receptor, the presence of which may be essential for a functional interaction with an S‐specific receptor.