bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cladistic analysis of Coenosiini (Diptera: Muscidae: Coenosiinae)
Authors: Couri Márcia S. , Pont Adrian C. 
Published: March 2003

SummaryThe phylogenetic relationships among world genera of Coenosiini (Diptera: Muscidae: Coenosiinae) were investigated using parsimony. The analysis involved forty‐six ingroup terminal taxa, representing 100% of the genera currently assigned to this tribe, three outgroups and sixty‐seven adult male and female morphological characters. The monophyly of Coenosiini is confirmed by the position of the three katepisternal bristles, equidistant from each other and placed at the points of an equilateral triangle. Genera Andersonosia, Agenamyia, Anthocoenosia, Drepanocnemis, Pachyceramyia and Rhabdotoptera are removed from Coenosiini and temporarily placed in Limnophorini. The other genera fall into two groups: the Lispocephala‐group, comprised of genera with mainly Old World species and the Nearctic genus Pentacricia; and the Coenosia‐group, with the highest level of generic diversity in South America. Each group is defined by synapomorphies of its constituent genera: Lispocephala‐group by the presence of a posteroventral apical seta on the hind tibia, the presence of two arms in male sternite 6 (not forming a ring) and the short or very short female ovipositor; the Coenosia‐group by the presence of a developed epiproct and narrow sternites 6 and 7 of the female ovipositor. The following new generic synonymies are proposed (junior synonyms in parentheses): Lispocephala Pokorny (=Pectiniseta Stein), Coenosia Meigen (=Tenuicosta Stein; Dexiopsis Pokorny), Neodexiopsis Malloch (=Haroldopsis Albuquerque), Pilispina Albuquerque (=Levallonia Albuquerque; Noelia Albuquerque; Parvomusca Medeiros; Cholomyioides Albuquerque), Apsil Malloch (=Raymondomyia Malloch), Stomopogon Malloch (=Angolia Malloch; Angolina Pont) and Pygophora Schiner (=Chouicoenosia Cui & Xue).
Organ‐dependent regulation of a plant promoter isolated from rice by 'promoter‐trapping' in tobacco.
Authors: Claes B , Smalle J , Dekeyser R , Van Montagu M , Caplan A 
Published: March 2003

SummaryA vector containing a transcriptionally inactive neomycin phosphotransferase II gene was used to select promoter sequences from a pool of random genomic DNA fragments. This paper describes how one such sequence (P4.7) isolated from Oryza sativa acts as a hormonally regulated promoter in Nicotiana tabacum. Relative expression ratios in leaf, root, midrib, callus, and stem tissue of tobacco plants are 1:5:4:10:17. Histochemical assays show that P4.7 activates the uidA reporter gene throughout the phloem and cortex of tobacco stems. Transcription from the P4.7 fragment is inducible in leaf tissue by low levels of alpha‐naphthalene acetic acid or 6‐benzyl‐aminopurine, even when cell proliferation is inhibited by colchicine or hydroxyurea. Conversely, 1% DMSO was found to inhibit activation of P4.7 without interfering with callus formation. The fragment contains TATA and CAAT sequences normally found at the 5' end of many plant genes, and an additional region homologous to sequences located in similar positions in a variety of similarly regulated promoters. Promoter deletion and fusion experiments have indicated the location of a stem enhancer element in P4.7. The promoter trap system we have described may potentially be used to characterize transcriptional factors common to monocot and dicot species.
Genome reorganization in Nicotiana asymmetric somatic hybrids analysed by in situ hybridization
Authors: Parokonny A. S. , Kenton A. Y. , Gleba Y. Y. , Bennett M. D. 
Published: March 2003

Summary In situ hybridization was used to examine genome reorganization in asymmetric somatic hybrids between Nicotiana plumbaginifolia and Nicotiana sylvestris obtained by fusion of gamma‐irradiated protoplasts from one of the parents (donor) with non‐irradiated protoplasts from the other (recipient). Probing with biotinylated total genomic DNA from either the donor or the recipient species unequivocally identified genetic material from both parents in 31 regenerant plants, each originating from a different nuclear hybrid colony. This method, termed genomic in situ hybridization (GISH), allowed intergenomic translocations containing chromosome segments from both species to be recognized in four regenerants. A probe homologous to the consensus sequence of the Arabidopsis thaliana telomeric repeat (5′‐TTTAGGG‐3′)n, identified telomeres on all chromosomes, including ‘minichromosomes’ originating from the irradiated donor genome. Genomic in situ hybridization to plant chromosomes provides a rapid and reliable means of screening for recombinant genotypes in asymmetric somatic hybrids. Used in combination with other DNA probes, it also contributes to a greater understanding of the events responsible for genomic recovery and restabilization following genetic manipulation in vitro.
Stress induction and developmental regulation of a rice chitinase promoter in transgenic tobacco
Authors: Zhu Qun , Doerner Peter W. , Lamb Christopher J. 
Published: March 2003

SummaryA 1.5 kb promoter fragment from the rice (Oryza sativa L.) RCH10 gene, which encodes a basic endochitinase inducible by wounding and fungal elicitor, was translationally fused to the β‐glucuronidase (GUS) reporter gene and transferred to tobacco by Agrobacterium tumefaciens‐mediated leaf disc transformation. Wounding of leaves induced GUS activity from low basal levels, and addition of fungal elicitor to the wounded tissue caused a further marked activation of the gene fusion. During vegetative development high levels of GUS activity were observed in roots and moderate levels in stems. Histochemical analysis indicated that the promoter was active in vascular and epidermal tissue, and the root apical tip. In flowers, high levels of GUS activity were observed in stigmas, ovaries and pollen‐containing anthers, but only low levels in sepals and petals. The promoter 5′‐deleted to −160 exhibited the same patterns of expression in floral organs, and was also strongly induced by wounding and elicitor, but GUS activity was markedly reduced in vegetative organs. More detailed 5′ deletions showed that a cis‐element required for floral expression was located between −160 and −74, and a cis element sufficient for stress induction was located 3′ of −74. This proximal region 3′ of −74 was also sufficient for expression in transfected rice protoplasts derived from suspension cultured cells. These data indicate that the complex developmental and environmental regulation of RCH10 promoter activity involves several distinct cis‐elements for vegetative expression, floral expression and stress induction, and that signal pathways for wound and elicitor induction are conserved between monocotyledonous and dicotyledonous plants.
Flavonols and fertilization in Petunia hybrida: localization and mode of action during pollen tube growth
Authors: Ylstra Bauke , Busscher Jacqueline , Franken John , Hollman Peter C.H. , Mol Joseph N.M. , Van Tunen Arjen J. 
Published: March 2003

SummaryFlavonols form an important class of flavonoids which serve an essential function during plant reproduction. Flavonoid biosynthesis is initiated by the enzyme chalcone synthase (CHS). A high abundance of flavonols and chs mRNA was demonstrated in male and female reproductive organs of Petunia hybrida. Detailed analyses revealed precise spatial and temporal regulation of the chs promoter and flavonol synthesis in the stigma, style and ovules. Transgenic plants were generated with a complete block of flavonol biosynthesis as the result of anti‐sense inhibition of chs gene activity. The absence of flavonols by this dominant mutation rendered these plants self‐sterile. Pollination experiments with wild‐type and mutant plants revealed that the production of flavonols in either the anthers or the pistils was required for pollen tube growth and seed set. Mutant pollen without flavonols in their exine germinated normally. However, after a short period of in vitro pollen tube growth the tips of these tubes disrupted and the protoplasm was disloaded leading to the death of the pollen grain. Addition of flavonol aglycones but not other flavonoids complemented this phenotype. Confocal laser scanning microscopy revealed the localization of high levels of flavonols throughout the wild‐type pollen tube. These compounds were not detected in the exine or cell wall of growing tubes. In addition, it was observed that the flavone apigenin could completely inhibit pollen tube growth. Taken together, it is shown that flavonols play an important role in the growth of the pollen tube and their mode of action is discussed.
Characterization of an Arabidopsis cDNA for a soluble epoxide hydrolase gene that is inducible by auxin and water stress
Authors: Kiyosue Tomohiro , Beetham Jeffrey K. , Pinot Frank , Hammock Bruce D. , Yamaguchi‐Shinozaki Kazuko , Shinozaki Kazuo 
Published: March 2003

SummaryA cDNA (1122 bp) was isolated from a cDNA library prepared from Arabidopsis thaliana L. that had been subjected to drought stress for 1 h. The sequencing of a genomic clone corresponding to the cDNA and S1 mapping analysis revealed that the cDNA lacked the first 6 bp from its translational start (ATG). The resulting open reading frame encodes a polypeptide of 321 amino acids, and the calculated molecular weight of this polypeptide is 36 423 Da. The deduced amino acid sequence shows a high degree of similarity to C terminal halves of those of soluble epoxide hydrolases (sEHs) of human, mouse and rat, 35.5%, 34.1% and 33.1%, respectively. The cDNA was expressed in Escherichia coli cells, and the expressed protein migrates at 40 kDa when analyzed by SDS—PAGE. The recombinant protein at 40 kDa is much smaller than the mammalian sEH (58 kDa) but has characteristics of activity and inhibition similar to the mammalian sEHs when assayed with the substrate trans‐stilbene oxide and the inhibitors 4‐fluorochalcone oxide (4FCO), (2R,3R)‐3‐(4‐nitrophenyl) glycidol (RRNPG), and (2S,3S)‐3‐(4‐nitrophenyl)glycidol (SSNPG), which indicates that the cDNA did encode a soluble epoxide hydrolase of A. thaliana (AtsEH). Drought stress, but not heat or cold stress, slightly increased the accumulation of the mRNAs for AtsEH. The level of AtsEH transcripts increased strongly after treatment with a plant hormone, auxin (2,4‐dichlorophenoxyacetic acid, 2,4‐D; naphthaleneacetic acid, NAA; and indole‐3‐acetic acid, IAA) in young, pre‐bolting plants. Treatment with cytokinin (6‐benzylaminopurine, BA), abscisic acid (ABA) or gibberellin (GA3) had no detectable effect on AtsEH transcript levels. The transcripts for AtsEH gene were detected in the aerial vegetative organs of bolting plants (i.e. stems and leaves), but not in roots, flowers and seeds. The possible function of AtsEH is discussed. A similar sEH cDNA has recently been characterized in potato (Stapleton et al., 1994).
Auxin‐dependent microtubule responses and seedling development are affected in a rice mutant resistant to EPC
Authors: Nick Peter , Yatou Osamu , Furuya Masaki , Lambert Anne‐Marie 
Published: March 2003

SummaryMutants in rice (Oryza sativa L. cv. japonica) were used to study the role of the cytoskeleton in signal‐dependent morphogenesis. Mutants obtained by gamma ray irradiation were selected that failed to show inhibition of coleoptile elongation by the antimicrotubular drug ethyl‐N‐phenylcarbamate (EPC). The mutation EPC‐Resistant 31 (ER31), isolated from such a screen, caused lethality in putatively homozygous embryos. Heterozygotes exhibited drug resistance, impaired development of crown roots, and characteristic changes in the pattern of cell elongation: cell elongation was enhanced in mesocotyls and leaf sheaths, but inhibited in coleoptiles. The orientation of cortical microtubules changed correspondingly: for etiolated seedlings, compared with the wild‐type, they were more transverse with respect to the long cell axis in mesocotyls and leaf sheaths, but more longitudinal in coleoptiles. In mutant coleoptiles, in contrast to wild‐type, microtubules did not reorient in response to auxin, and their response to microtubule‐eliminating and microtubule‐stabilizing drugs was conspicuously reduced. In contrast, they responded normally to other stimuli such as gibberellins or red light. Auxin sensitivity as assayed by the dose‐response for callus induction did not show any significant differences between wild‐type and mutant. The mutant phenotype is interpreted in terms of an interrupted link between auxin‐triggered signal transduction and microtubule reorientation.
The Arabidopsis ribonuclease gene RNS1 is tightly controlled in response to phosphate limitation
Authors: Bariola Pauline A. , Howard Christie J. , Taylor Crispin B. , Verburg Michael T. , Jaglan Vanita D. , Green Pamela J. 
Published: March 2003

SummaryTwo stimuli that have been associated with nutrient remobilization in plants are phosphate (PI) starvation and senescence. Little is known about how the nutrient remobilization machinery is induced at the molecular level, but in the case of Pi starvation, ribonucleases are considered to play important roles in the remobilization process. Here, the control of two closely related ribonuclease genes of Arabidopsis, RNS1 and RNS3 is investigated. The RNS1 gene is sharply induced during starvation for Pi, an effect specific among the major macronutrients, whereas RNS3 transcript levels remain relatively constant. RNS1 and RNS3 produced in yeast co‐migrate with Arabidopsis ribonuclease activities that exhibit the same induction properties as the transcripts in both wild‐type plants and the pho1 mutant, which is defective in xylem loading of Pi. In contrast to what occurs during Pi starvation, both RNS1 and RNS3 are modestly induced during senescence, indicating that the two stimuli could trigger different signal transduction pathways. The characterization of RNS1, in particular, provides an important first step towards elucidating the mechanisms by which plants sense and respond to Pi limitation, a prominent condition in many soil types.
Real‐time imaging of phloem unloading in the root tip of Arabidopsis
Authors: Oparka K.J. , Duckett C.M. , Prior D.A.M. , Fisher D.B. 
Published: March 2003

SummaryConfocal laser scanning microscopy (CLSM) has been used to image phloem transport and unloading in the root tip of Arabidopsis. The fluorescent probe 5(6) carboxyfluorescein (CF) was ester loaded into a single cotyledon and the entire seedling placed within an observation chamber under the microscope. Translocation of CF to the root tip was rapid, followed by unloading into discrete concentric files of cells. The position of the prominent unloading ‘zone’ corresponded precisely with that of the two protophloem files of sieve elements, demonstrating a functional role of these cells in symplastic sieve‐element unloading. Symplastic transport following unloading was confined to the elongating zone of the root with little basipetal transport to more mature cells. Following photobleaching of the unloading zone, phloem transport was restored immediately into the protophloem sieve elements, followed rapidly by lateral, symplastic sieve‐element unloading. The results demonstrate that phloem transport processes can now be imaged in real time, and non‐invasively, within an intact plant system.
Heat‐inducible expression of FLP gene in maize cells
Authors: Lyznik Leszek A. , Hirayama Lynne , Rao K.V. , Abad Andre , Hodges Thomas K. 
Published: March 2003

The soybean heat‐shock gene promoter (Gmhsp 17.5‐E) has been used to direct expression of gusA and FLP genes in maize cells. At inducible temperatures, in transient expression assays, gusA gene expression controlled by the heat‐shock promoter is about 10‐fold higher than the expression directed by the CaMV 35S promoter. The Gmhsp 17.5‐E promoter preserves its regulatory functions in heterologous maize cells after random integration into genomic DNA.Heat‐shock inducible expression of the FLP gene was investigated by co‐transformation of the FLP expression vector (pHsFLP) and a recombination test vector (pUFNeo‐FmG) into maize protoplasts. Co‐transformed protoplasts were incubated at 42°C for 2 h. This treatment induced recombination of 20–25% of the available FRT sites in transient assays. As a result of heat‐shock treatment of stably co‐transformed maize cells, activation of gusA gene expression and an associated decrease or elimination of NPT‐II activity in transgenic maize lines was observed. Molecular evidence was obtained of the expected DNA excision process catalyzed by the FLP protein in maize transgenic cells. Thus, the experiments presented in this paper indicate that the FLP protein can recognize and subsequently recombine the FRT target sites that had integrated into plant genomic DNA, and that regulated expression of the FLP gene is possible in maize cells using the soybean heat‐shock promoter.
Isolation of two soybean G‐box binding factors which interact with a G‐box sequence of an auxin‐responsive gene
Authors: Hong Jong Chan , Cheong Yong Hwa , Nagao Ron T. , Bahk Jeong Dong , Key Joe L. , Cho Moo Je 
Published: March 2003

G‐box binding factors (GBFs) constitute a family of plant DNA‐binding proteins that bind to the G‐box motif, a regulatory cis element present in many plant genes with a palindromic DNA motif of CACGTG. Previously TCCACGTGTC, a G‐box motif, from an auxin responsive gene GmAux28 has been identified as a sequence‐specific protein‐binding site. Here the isolation of two soybean cDNA clones, referred to as SGBF‐1 and SGBF‐2, encoding proteins which bind to the G‐box motif is reported. The primary structure of SGBF‐1 and SGBF‐2 predicts that these proteins contain a basic leucine zipper (bZIP) DNA‐binding domain and an N‐terminal proline‐rich domain.A dramatic difference in the pattern of protein‐DNA complex formation was observed when recombinant SGBF‐1 and SGBF‐2 proteins were analyzed by electrophoretic mobility shift assays (EMSAs). The SGBF‐1 binding pattern obtained with the G‐box probe resulted in three major retarded bands while the SGBF‐2 formed a single complex. This shows that the characteristically diffuse banding pattern of plant nuclear proteins interacting with the G‐box is also observed in a binding assay using only one recombinant GBF. EMSAs were performed with a few selected binding sequences to study the effect of flanking nucleotides to the hexanucleotide G‐box core motif. The binding specificity of the SGBF proteins resembles that described for type A cauliflower nuclear G‐box binding proteins which bind class I G‐box elements [(G/T)(C/A)CACGTG(G/T)(A/C)]. Phylogenetic analysis of 13 GBF‐like proteins from various plant species reveals that the SGBF‐1 and SGBF‐2 proteins belong to different lineages, suggesting that they may have distinct functions in activating transcription.
Use of RFLPs larger than 100 kbp to map the position and internal organization of the nucleolus organizer region on chromosome 2 in Arabidopsis thaliana
Authors: Copenhaver Gregory P. , Doelling Jed H. , Gens J. Scott , Pikaard Craig S. 
Published: March 2003

SummaryIn Arabidopsis thaliana ribosomal RNA genes (rRNA genes or rDNA) are grouped in two nucleolus organizer regions (NORs) that together comprise approximately 6% of the genome. The map positions of the NORs relative to other genetic markers are unknown. It was found that the restriction endonuclease HindIII cuts once in some but not all rRNA genes to yield strain‐specific RFLPs of 100–700 kb that could be visualized by pulsed‐field gel electrophoresis and Southern blotting. The HindIII RFLPs of the A. thaliana strains Columbia and Landsberg segregated among recombinant inbred lines derived from a cross between these two strains. Linkage analysis placed the NOR bearing the polymorphic HindIII sites to the top of the upper arm of chromosome 2. The name NOR2 is suggested for this locus. HindIII‐bearing rRNA genes are interspersed with clusters of HindIII‐less genes throughout NOR2. The observed clustering is most consistent with unequal crossing‐over, or nearest‐neighbor gene conversion, as the mechanism(s) that spread rRNA gene variants throughout an NOR. No meiotic cross‐over events yielding a ‘hybrid’ NOR with multiple RFLPs from both parents were observed among the 47 recombinant inbred lines examined. However, the appearance of novel HindIII profiles in approximately 40% of the recombinant inbred lines demonstrates that fluctuations in the distribution of rRNA gene variants occur frequently and can be readily detected on pulsed‐field gels.
Transcript processing internal to a mitochondrial open reading frame is correlated with fertility restoration in male‐sterile sorghum
Authors: Tang Hoang V. , Pring Daryl R. , Shaw Lynn C. , Salazar Reggie A. , Muza Figuhr R. , Yan Bin , Schertz Keith F. 
Published: March 2003

SummaryA chimeric mitochondrial DNA (mtDNA) configuration of the cytoplasmic male‐sterile (cms) sorghum line IS1112C includes a 321 bp open reading frame designated orf107, encoding a predicted polypeptide product of 11.85 kDa. The open reading frame, similar to several other genes associated with cms, consists of amino‐terminal sequences derived from an obligate gene. Unlike other examples to date, however, the carboxy‐terminal sequences are highly similar to the carboxy terminus of an open reading frame implicated in cms of rice, orf79. The amino‐terminal 31 residues of orf107 are 84% similar to atp9, and the carboxy‐terminal 49 residues are 57% identical and 80% similar to the carboxy terminus of orf79. Transcripts of orf107 are edited, with four C‐to‐U changes that alter amino acids. Sorghum lines partially or fully restored to fertility exhibit a high‐efficiency internal‐orf107 transcript processing activity, precluding abundant whole‐length transcripts, while male‐sterile lines exhibit only a trace of the activity. Previous data on the abundance of a 12 kDa in organello‐synthesized polypeptide in male‐sterile versus male‐fertile lines are correlated with differential orf107 transcript processing activity of these lines. Examinations of backcross and F2 lines suggest a gametophytic mode of restoration, and indicate that enhanced transcript processing activity is necessary, but not sufficient, to restore full fertility. These novel observations indicate that mitochondrial open reading frames associated with cms in different species can include highly similar motifs, and that fertility restoration could involve a mechanism by which synthesis of a cms‐associated gene product may be precluded through internal transcript cleavage.
Transactivation of a target gene using a suppressor tRNA in transgenic tobacco plants
Authors: Choisne Nathalie , Martin‐Canadell Alfred , Small Ian 
Published: March 2003

SummaryThe abundance of tRNAs, together with their central role in translation, has generated considerable interest in the use of tRNA genes for biotechnological applications. One such application is the use of suppressor tRNAs to transactivate target genes containing premature stop codons. Previous work has shown that such systems can work in transient expression experiments in plant protoplasts; here these experiments are extended to show that suppression of stop codons can occur in whole plants. Transgenic tobacco plants homozygous for a modified tRNALeu gene expressing a strong amber suppressor tRNA, and plants carrying a β‐glucuronidase (gus) gene inactivated by a premature amber stop codon have been obtained. When the two types of plants are crossed, many of the F1 hybrids show significant GUS activity. The GUS activity is dependent on the presence of both the suppressor tRNA gene and the gus gene. Tobacco plants carrying the suppressor tRNA gene are phenotypically normal, fertile and the gene shows normal Mendelian inheritance. The potential applications of such a system are discussed.