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  • 1
    Electronic Resource
    Electronic Resource
    Cloning of a Picea abies monosaccharide transporter gene and expression – analysis in plant tissues and ectomycorrhizas (2000)
    Springer
    Trees 14 (2000), S. 334-338 
    Details
    ISSN: 0931-1890
    Keywords: Key words  Picea abies ; Monosaccharide transporter ; Gene expression ; Ectomycorrhizas ; Carbon allocation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  Ectomycorrhizas are formed between certain soil fungi and fine roots of woody plants. An important feature of this symbiosis is the supply of photoassimilates to the fungus. Hexoses, formed from sucrose in the common apoplast at the root/fungus interface, can be taken up by both plant and fungal monosaccharide transporters. Recently we characterised a monosaccharide transporter from the ectomycorrhizal fungus Amanita muscaria. This transporter was up-regulated in mycorrhizas, thus increasing the hexose uptake capacity of the fungal partner in symbiosis. In order to characterise host (Picea abies) root monosaccharide transporters, degenerate oligonucleotide primers, designed to match conserved regions from known plant hexose transporters, were used to isolate a cDNA fragment of a transporter by PCR. This fragment was used to identify a presumably full length clone (PaMST1) in a P. abies/A. muscaria mycorrhizal cDNA library. The entire cDNA code for an open reading frame of 513 amino acids, revealing best homology to H+/monosaccharide transporters from Ara- bidopsis, Saccharum and Ricinus. PaMST1 was highly expressed in the hypocotyl and in roots of P. abies seedlings, but not in needles. Mycorrhiza formation led to a slight reduction of PaMST1 expression. The results are discussed with special reference to carbon allocation in ectomycorrhizas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004680050227
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  • 2
    Electronic Resource
    Electronic Resource
    Photosynthesis and fluorescence quenching, and the mRNA levels of plastidic glutamine synthetase or of mitochondrial serine hydroxymethyltransferase (SHMT) in the leaves of the wild-type and of the SHMT-deficient stm mutant of Arabidopsis thaliana in relation to the rate of photorespiration (1997)
    Springer
    Planta 202 (1997), S. 379-386 
    Details
    ISSN: 1432-2048
    Keywords: Key words:Arabidopsis (stm mutant) ; Gas exchange ; Gene expression ; Glutamine synthetase ; Mutant (Arabidopsis ; stm) ; Photorespiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. The regulation by photorespiration of the transcript level corresponding to plastidic glutamine synthetase (GS-2) was investigated in the leaves of Arabidopsis thaliana (L.) Heynh.. Photorespiration was suppressed by growing the plants in an atmosphere containing 300 Pa CO2. Suppression of photorespiration was demonstrated by the ability of the conditionally lethal serine hydroxymethyltransferase (SHMT)-deficient stm mutant of A. thaliana to grow normally under these conditions. In contrast to previous studies with bean or pea that were performed at very high CO2 partial pressure (2–4 kPa; Edwards and Coruzzi, 1989, Plant Cell 1: 241–248; Cock et al., 1991, Plant Mol Biol 17: 761–771), suppression of photorespiration during growth of A. thaliana in an atmosphere with 300 Pa CO2 had no effect on the leaf GS-2 transcript level. In the short term, neither suppression of photorespiration induced by the transfer of air-grown A. thaliana plants into a CO2-enriched atmosphere, nor an increase in the rate of photorespiration achieved by the transfer of high-CO2-grown A. thaliana plants into air resulted in a change in the GS-2 mRNA level. The absence of photorespiratory ammonium release in leaves of the stm mutant had no effect on the GS-2 transcript level. Overall, our data argue against a control by photorespiration of the A. thaliana leaf GS-2 mRNA pool. In contrast, regulation of the leaf SHMT mRNA level may involve a negative feedback effect of at least one metabolite derived from the glycine/serine conversion during photorespiration, as indicated by the overexpression of SHMT transcripts in the leaves of the stm mutant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004250050140
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  • 3
    Electronic Resource
    Electronic Resource
    Repetitious structure and transcription control of a polyubiquitin gene in Volvox carteri (1994)
    Springer
    Current genetics 25 (1994), S. 169-177 
    Details
    ISSN: 1432-0983
    Keywords: Polyubiquitin gene ; Gene homogenization ; Gene expression ; Heat-shock promoter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Southern analysis indicated the presence of at least four ubiquitin gene loci in the Volvox carteri genome. Three of these, a polyubiquitin gene described here and a non-segregating ubiquitin gene pair, were assigned to two different linkage groups by RFLP mapping; the non-polymorphic fourth gene locus remained unassigned. The polyubiquitin gene was cloned and its 2,116-bp sequence determined. It contains six exons each interrupted by an intron at Gly35, and it encodes a pentameric polyubiquitin polypeptide consisting of five runs of 76 identical amino-acid residues and a C-terminal extension of one leucine. The five tandem repeats of coding units plus introns exhibit an unusually high degree of overall sequence identity indicating an efficient process of gene homogenization in this region of the V. carteri genome. S1 mapping revealed two closely-spaced transcription starts, 24 and 28 nucleotides downstream from a putative TATA sequence. Preceding the TATA box are two 14-bp conserved heat-shock elements (HSEs) and two octameric sequences closely resembling an yeast HSE. Consistent with a 1.6-kb transcript seen on Northern blots are two polyadenylation signals (TGTAA) located 99 bp and 169 bp downstream from the TGA translational stop. The polyubiquitin gene was transcribed throughout the Volvox life cycle with peaks in the 1.6-kb mRNA levels during pre-cleavage, cleavage, and post-inversion. In contrast, an 0.6-kb monoubiquitin transcript was abundant only at the pre-cleavage stage suggesting a different type of gene control. Heat shock increased the level of polyubiquitin mRNA, whereas the level of monoubiquitin mRNA was down-regulated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00309544
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  • 4
    Electronic Resource
    Electronic Resource
    The organization structure and regulatory elements of Chlamydomonas histone genes reveal features linking plant and animal genes (1995)
    Springer
    Current genetics 28 (1995), S. 333-345 
    Details
    ISSN: 1432-0983
    Keywords: Green algae ; Volvox ; Transcription signals ; Gene expression ; Intron ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The genome of the green alga Chlamydomonas reinhardtii contains approximately 15 gene clusters of the nucleosomal (or core) histone H2A, H2B, H3 and H4 genes and at least one histone H1 gene. Seven non-allelic histone gene loci were isolated from a genomic library, physically mapped, and the nucleotide sequences of three isotypes of each core histone gene species and one linked H1 gene determined. The core histone genes are organized in clusters of H2A–H2B and H3–H4 pairs, in which each gene pair shows outwardly divergent transcription from a short (300 bp) intercistronic region. These intercistronic regions contain typically conserved promoter elements, namely a TATA-box and the three motifs TGGCCAG-G(G/C)-CGAG, CGTTGACC and CGGTTG. Different from the genes of higher plants, but like those of animals and the related alga Volvox the 3′ untranslated regions contain no poly A signal, but a palindromic sequence (3′ palindrome) essential for mRNA processing is present. One single H1 gene was found in close linkage to a H2A–H2B pair. The H1 upstream region contains the octameric promoter element GGTTGA-CC (also found upstream of the core histone genes) and two specific sequence motifs that are shared only with the Volvox H1 promoters. This suggests differential transcription of the H1 and the core histone genes. The H1 gene is interrupted by two introns. Unlike Volvox H3 genes, the three sequenced H3 isoforms are intronfree. Primer-directed PCR of genomic DNA demonstrated, however, that at least 8 of the about 15 H3 genes do contain one intron at a conserved position. In synchronized C. reinhardtii cells, H4 mRNA levels (representative of all core histone mRNAs) peak during cell division, suggesting strict replication-dependent gene control. The derived peptide sequences place C. reinhardtii core histones closer to plants than to animals, except that the H2A histones are more animal-like. The peptide sequence of histone H1 is closely related to the V. carteri VH1-II (66% identity). Organization of the core histone gene in pairs, and non-polyadenylation of mRNAs are features shared with animals, whereas peptide sequences and enhancer elements are shared with higher plants, assigning the volvocalean histone genes a position intermediate between animals and plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00326431
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  • 5
    Electronic Resource
    Electronic Resource
    Structure, expression, and phylogenetic relationships of a family of ypt genes encoding small G-proteins in the green alga Volvox carteri (1993)
    Springer
    Current genetics 24 (1993), S. 229-240 
    Details
    ISSN: 1432-0983
    Keywords: ypt genes ; rab gene family ; Gene expression ; Nucleotide sequence ; GTP-binding ; Ras superfamily ; Phylogeny ; Green algae ; Volvocales
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In addition to the previously described gene yptV1 encoding a small G-protein we have now identified and sequenced four more ras-related ypt genes (yptV2-yptV5) from the green alga Volvox carteri. The four new genes encode polypeptides consisting of 203 to 217 amino-acid residues that contain the typical sequence elements (GTP-binding domains, effector domain) of the ypt/rab subgroup of the Ras superfamily. Comparison of the derived amino-acid sequences from the V. carteri ypt gene products and their Ypt homologs from other species revealed similarity values ranging from 60% to 85%, whereas intraspecies similarities were found to approach only 55%. The coding sequences are interrupted by 5–7 introns of variable size (70–1000 nucleotides) occupying different positions in the genes. Reverse-transcribed samples of stage-specific RNAs were PCR-amplified with primers specific to yptV1, yptV3, yptV4, and yptV5 to determine if yptV transcription might be restricted to either cell type or to a specific stage of the life cycle. These experiments demonstrated that each of these genes is expressed throughout the entire Volvox life cycle and in both the somatic and the reproductive cells of the alga. The transcription start sites of yptV1 and yptV5 were mapped by primer extension. Expression of recombinant yptV cDNA in E. coli yielded recombinant proteins that bound GTP specifically, demonstrating a property which is typical for small G-proteins. The derived YptV polypeptide sequences were used to group them into four distinct classes of Ras-like proteins. These are the first proteins of the Ras superfamily to be identified in a green alga. We discuss the possible role of the YptV-proteins in the intracellular vesicle transport of Volvox.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00351797
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