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  • 1
    Electronic Resource
    Electronic Resource
    Phloem specific aphid resistance in Cucumis melo line AR 5: effects on feeding behaviour and performance of Aphis gossypii (1998)
    Springer
    Entomologia experimentalis et applicata 86 (1998), S. 79-88 
    Details
    ISSN: 1570-7458
    Keywords: host plant resistance ; feeding ; behaviour ; melon ; Cucumis melo ; aphid ; Aphis gossypii ; phloem ; electrical penetration graph ; EPG ; honeydew
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The feeding behaviour, excretion rate, and life history traits of the cotton-melon aphid, Aphis gossypii (Glover) (Homoptera, Aphididae), were measured on a resistant melon, Cucumis melo L., breeding line, AR 5. The site of resistance detection by the aphids was determined using the electrical penetration graph (EPG) technique. EPG recordings showed that resistance is expressed within the host plant, rather than on its surface, because the time to first stylet penetration was not significantly different between AR 5 and the closely related susceptible breeding line, PMR 5. EPG patterns associated with stylet pathway activities of the aphids were not significantly different between the resistant and susceptible lines. Significant behavioural differences were observed only after stylets contacted phloem sieve elements. On AR 5, the duration of salivation after sieve element puncture (waveform E1) was significantly longer, and the number of aphids showing phloem sap ingestion (waveform E2) was significantly reduced. We conclude that the resistance mechanism producing the effects seen in this study acts within the phloem sieve elements. Monitoring of excretion rates on the two genotypes showed that aphid feeding was delayed and greatly reduced on the resistant genotype. Comparisons of aphid life history traits and population development between host plant genotypes showed that the effects of resistance act throughout aphid development and are highly effective at slowing down population increase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003153410049
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  • 2
    Electronic Resource
    Electronic Resource
    Expression of the phloem lectin is developmentally linked to vascular differentiation in cucurbits (1997)
    Springer
    Planta 201 (1997), S. 405-414 
    Details
    ISSN: 1432-2048
    Keywords: Key words: Companion cell ; Cucurbita (phloem lectin) ; Lectin (PP2) ; Phloem protein ; Sieve element ; Vascular differentiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. The conducting elements of phloem in angiosperms are a complex of two cell types, sieve elements and companion cells, that form a single developmental and functional unit. During ontogeny of the sieve element/companion cell complex, specific proteins accumulate forming unique structures within sieve elements. Synthesis of these proteins coincides with vascular development and was studied in Cucurbita seedlings by following accumulation of the phloem lectin (PP2) and its mRNA by RNA blot analysis, enzyme-linked immunosorbent assay, immunocytochemistry and in␣situ hybridization. Genes encoding PP2 were developmentally regulated during vascular differentiation in hypocotyls of Cucurbita maxima Duch. Accumulation of PP2 mRNA and protein paralleled one another during hypocotyl elongation, after which mRNA levels decreased, while the protein appeared to be stable. Both PP2 and its mRNA were initially detected during metaphloem differentiation. However, PP2 mRNA was detected in companion cells of both bundle and extrafascicular phloem, but never in differentiating sieve elements. At later stages of development, PP2 mRNA was most often observed in extrafascicular phloem. In developing stems of Cucurbita moschata L., PP2 was immunolocalized in companion cells but not to filamentous phloem protein (P-protein) bodies that characterize immature sieve elements of bundle phloem. In contrast, PP2 was immunolocalized to persistent ␣ P-protein bodies in sieve elements of the extrafascicular phloem. Immunolocalization of PP2 in mature wound sieve elements was similar to that in bundle phloem. It appears that PP2 is synthesized in companion cells, then transported into differentiated sieve elements where it is a component of P-protein filaments in bundle phloem and persistent P-protein bodies in extrafascicular phloem. This differential accumulation in bundle and extrafascicular elements may result from different functional roles of the two types of phloem.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004250050083
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  • 3
    Electronic Resource
    Electronic Resource
    Analysis of promoter activity from an α-zein gene 5′ flanking sequence in transient expression assays (1990)
    Springer
    Plant molecular biology 15 (1990), S. 755-764 
    Details
    ISSN: 1573-5028
    Keywords: maize gene expression ; protoplasts ; transient assays ; transcriptional regulation ; zein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Three DNA regions required for high levels of transcription were identified by transient gene expression analysis of the 5′ flanking region of a 19 kDa α-zein gene. For these analyses, the zein promoter region was fused to the β-glucuronidase (GUS) gene and assayed by transient expression in carrot protoplasts. A 107-bp sequence (-114/-8) containing the TATA box resulted in low levels of GUS activity. Addition of the proximal 75 bp (-189/-114) doubled the level of GUS expression, and a further increase in expression was obtained when additional upstream sequences (-483/-226) were placed 5′ of the zein promoters. Zein upstream sequences enhanced transcription independently of the-189/-114 region. Although the-189/-114 region was not essential for transcription, it was important to obtain maximum GUS activity. A 121 bp upstream sequence (-347/-226) that contains the conserved TGTAAAG sequence gave high levels of GUS activity when placed in either orientation 5′ of the zein promoter sequences. However, nucleotides-347 to-309, containing the TGTAAAG sequence, could be deleted from this fragment without a significant change in GUS activity. Zein upstream sequences did not promote transcription of the GUS gene in somatic maize protoplasts. The upstream activating sequence from the cauliflower mosaic virus (CaMV) 35S promoter placed 5′ of deletion mutants of the zein promoter also failed to produce GUS activity above background.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00016125
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  • 4
    Electronic Resource
    Electronic Resource
    Sequence analysis of linked maize 22 kDa α-zein genes (1992)
    Springer
    Plant molecular biology 18 (1992), S. 827-833 
    Details
    ISSN: 1573-5028
    Keywords: α-zein ; gene duplication ; maize genes ; maize pseudogene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have determined the nucleotide sequence of a 7343 bp zein genomic clone (gZ22.8H3) from the maize inbred W64A. Computer-aided analysis of the DNA sequence revealed two contiguous 22 kDa α-zein genes. The 5′ gene (gZ22.8) encodes a complete polypeptide and contains putative regulatory sequences in both the 5′ and 3′ flanking regions that are typical of zein genes. In contrast, the 3′ gene (ψgZ22.8) appears to be a pseudogene, because it contains numerous insertions and deletions that would prevent translation of the mRNA. Alignment of the 5′ and 3′ flanking sequences of both genes indicated that they resulted from a 3.3 kb DNA duplication event.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00020030
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  • 5
    Electronic Resource
    Electronic Resource
    Normal and lysine-containing zeins are unstable in transgenic tobacco seeds (1991)
    Springer
    Plant molecular biology 16 (1991), S. 117-128 
    Details
    ISSN: 1573-5028
    Keywords: storage protein ; genetic engineering ; transgenic plants ; zeins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chimeric genes composed of the β-phaseolin promoter, an α-zein coding sequence and its modified versions containing lysine codons, and a β-zein polyadenylation signal were inserted into the genome of tobacco by Agrobacterium-mediated transformation. α-Zein mRNA levels in the transgenic tobacco seeds 20 days after self-pollination varied between 1.0% and 2.5% of the total mRNA population. At 25 days after pollination the 19 kDa α-zein was immunologically detected with a polyclonal antiserum in protein extracts from the seeds of transgenic plants. The transgenic plant with the highest level of zein gene expression had an α-zein content that was approximately 0.003% of the total seed protein. The amount of α-zein in other transgenic plants varied between 1 × 10−4% and 1 × 10−5% of the total seed protein. The differences in the amounts of mRNA and protein did not correlate with the lysine substitutions introduced into the α-zein protein. Polysomes translating α-zein mRNA isolated from tobacco seeds contained fewer ribosomes than those from maize endosperm, but this did not appear to be the cause of the inefficient protein synthesis. In vivo labelling and immunoprecipitation indicated that newly synthesized α-zein was degraded in tobacco seeds with a half-life of less than 1 hour.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00017922
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  • 6
    Electronic Resource
    Electronic Resource
    Organization and characterization of Cucurbita phloem lectin genes (1994)
    Springer
    Plant molecular biology 26 (1994), S. 887-897 
    Details
    ISSN: 1573-5028
    Keywords: Cucurbita ; phloem lectin ; phloem protein 2 ; PP2 gene ; pumpkin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The phloem of pumpkin and squash contains a dimeric chitin-binding lectin called PP2 (phloem protein 2). We have isolated three genomic clones from pumpkin (Cucurbita maxima Duch.) that encoded PP2. One clone, λgPC13-1, contained two PP2 genes that were 99.8% identical over a region of 3055 nucleotides. This conserved region included 1922 bp of 5′ non-coding sequence, 844 bp of protein coding sequence (including two introns), and 289 bp of 3′ non-coding sequence. To examine the conservation of the phloem lectin within the genus Cucurbita, we analyzed nine different species for PP2, its mRNA, and the genes that encode PP2. DNA blot analysis indicated that each species contained genes that encoded PP2, however, there was considerable restriction fragment length polymorphism (RFLP) among the species. PP2 gene copy number reconstructions indicated that PP2 is encoded by a small gene family (two to eight genes). Although a high level of PP2 DNA polymorphism existed among species, a single mRNA (ca. 1 kb) was detected in each species. PP2, affinity-purified from the vascular exudate of each species, reacted with PP2-specific antibodies; five species contained a single PP2 polypeptide while four species contained two PP2 polypeptides.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00028856
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  • 7
    Electronic Resource
    Electronic Resource
    Micropropagation of Mexican redbud, Cercis canadensis var. mexicana (1995)
    Springer
    Plant cell, tissue and organ culture 43 (1995), S. 295-299 
    Details
    ISSN: 1573-5044
    Keywords: Shoot culture ; tissue culture ; woody plant
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Mexican redbud (Cercis canadensis var. mexicana) shoot cultures were initiated from explants taken from both mature and juvenile stock plants. Culture conditions affecting shoot growth and proliferation and rooting of three clones were investigated. Shoot growth was best on media supplemented with 0.25% activated charcoal and solidified with 0.2% Gelrite. Four commercially available salt formulations (Anderson's rhododendron medium, WPM, MS, DKW) were tested for growth of shoot cultures, and Anderson's rhododendron basal salt mixture was superior. Axillary shoots grew from explants cultured media supplemented with a wide range of concentrations of benzyladenine and thidiazuron. Benzyladenine at 5.6–22.2 μM supported the best combination of shoot quality and number. Rooting of microshoots in vitro was best on half-strength WPM containing 6.71 μM naphthaleneacetic acid and 0.1% activated charcoal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00039959
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  • 8
    Electronic Resource
    Electronic Resource
    ABSPLOTS: A LOTUS 123 Spreadsheet for Calculating and Plotting Drug Absorption Rates (1988)
    Springer
    Pharmaceutical research 5 (1988), S. 247-248 
    Details
    ISSN: 1573-904X
    Keywords: Wagner–Nelson ; Loo–Riegelman ; deconvolution ; absorption ; input function ; computer program
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015954032126
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  • 9
    Electronic Resource
    Electronic Resource
    Structural elements regulating zein gene expression (1989)
    New York, NY : Wiley-Blackwell
    BioEssays 10 (1989), S. 108-113 
    Details
    ISSN: 0265-9247
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Zeins are a group of alcohol-soluble proteins that are synthesized in the endosperm of developing maize seeds. These proteins are encoded by a large number of genes located on several chromosomes; based upon the number of mutants that have been isolated, zein gene regulation is complex. Comparisons of gene flanking regions reveal conserved sequences that may be important for their regulation. Studies of transformed plant tissues support the assertion that cis-acting elements with the 5′ flanking regions of zein genes are required for accurate transcription. Although the genes are transcribed in transgenic tobacco and petunia plants, they are not properly regulated. This appears to be due to transcriptional effects rather than protein or mRNA instability.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bies.950100404
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