| 1. |
- Castillo Leon, Jaime, et al.
(författare)
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Purification and substrate specificity of peroxidase from sweet potato tubers
- 2002
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Ingår i: Plant Science. - 0168-9452. ; 163:5, s. 1011-1019
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Tidskriftsartikel (refereegranskat)abstract
- Previously the screening of tropical plants demonstrated a high peroxidase activity in sweet potato (Ipomoea batatas) tubers. The major peroxidase pool is localized in peel. Using peel of sweet potato as a source, the sweet potato peroxidase (SPP) has been isolated and purified to homogeneity. The enzyme purification included homogenization, extraction of colored compounds and consecutive chromatographies on Phenyl-Sepharose and DEAE-Toyopearl. The purified SPP had specific activity of 4900 U mg(-1) protein, RZ (ratio of absorbances at 403 and 280 nm, respectively) 3.4, molecular mass of 37 kDa and isoelectric point of 3.5. The spectrum of peroxidase from sweet potato is typical for plant peroxidases with a Soret maximum at 401 nm and the maxima in the visible region at 497 and 638 nm, respectively. The substrate specificity of SPP is distinct from the specificity of other plant peroxidases, ferulic acid being the best substrate for SPP.
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| 2. |
- Heiser, Volker, et al.
(författare)
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Antisense repression of the mitochondrial nadh-binding subunit of complex I in transgenic potato plants affects male fertility
- 1997
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Ingår i: Plant Science. - 0168-9452. ; 127:1, s. 61-69
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Tidskriftsartikel (refereegranskat)abstract
- Mitochondrial respiratory chain complex I is a large multi-subunit enzyme composed of both organellar and nuclear encoded proteins. To investigate the role of the nuclear encoded components, expression of the gene for the 55 kDa NADH-binding subunit of complex I was disturbed by antisense repression in transgenic potato plants. The antisense construct driven by the CaMV 35S promoter decreases the steady-state mRNA levels of transcripts for the 55 kDa subunit to 33% of the wild type levels. Quantities of the 55 kDa protein in mitochondrial protein extracts are lowered to about 50% in these plants. Transgenic plants show normal vegetative growth and tuber formation, but pollen maturation is found to be disturbed. The reduced male fertility of the transgenic 55 kDa antisense plants may be caused by an insufficient mitochondrial respiratory chain, impaired by the decreased expression of the NADH-binding component of mitochondrial complex I.
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| 3. |
- Petit, Patrice X., et al.
(författare)
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Properties of submitochondrial particles from plant mitochondria : generation, surface characteristics and NAD(P)H oxidation
- 1991
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Ingår i: Plant Science. - 0168-9452 .- 1873-2259. ; 78:2, s. 177-183
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Tidskriftsartikel (refereegranskat)abstract
- Purified mitochondria isolated from potato (Solanum tuberosum L. cv. Bintje) tuber, Jerusalem artichoke (Helianthus tuberosu L.) tuber and rat liver were disrupted at different pH and different EDTA and MgCl2 concentrations either by French Press treatment or by sonication. The submitochondrial particles (SMP) were isolated by differential centrifugation and polarity estimated by the latency of cytochrome c oxidase (CCO) activity. The SMP were 5-9% inside-out depending on the conditions, and the disruption method was more important than the composition of the disruption medium in determining the polarity. At pH 6 and 7 and high-salt conditions sonication yielded SMP of the same polarity (82-91% inside-out) whereas French Press treatment in a low-salt buffer + EDTA gave more inside-out SMP at pH 6 than at pH 7. The inside out vesicles were able to build up a membrane potential in the presence of respiratory substrates (as tested with the anionic dye, oxonol VI) whereas no membrane potantial could be detected with the right-side-out vesicles (as tested with cationic dyes, and optical dye, safranine O, and a fluorescent dye, rhodamine 123) under similar conditions. Binding of Concanavalin A indicated that both the inner and outer surface of the inner membrane have exposed glycoproteins and/or glycolipids. Both right-side-out and inside-out SMP oxidized NADH, NADPH and succinate with good rates but there were clear differences in both donor and acceptor specificity between the outer and inner surface of the inner mitochondrial membrane. NADH oxidation by inside-out SMP was Ca2+-independent and rotenone-inhibited whereas NADPH oxidation by the inside-out SMP was Ca2+-dependent and relatively unaffected by rotenone.
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| 4. |
- Baguma, Yona, et al.
(författare)
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Expression patterns of the gene encoding starch branching enzyme II in the storage roots of cassava (Manihot esculenta Crantz)
- 2003
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Ingår i: Plant Science. - 0168-9452 .- 1873-2259. ; 164:5, s. 833-839
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Tidskriftsartikel (refereegranskat)abstract
- Spatial and temporal expression patterns of the sbeII and sbeI genes, encoding starch branching enzyme II and I, respectively, in cassava (Manihot esculenta Crantz) were studied at different phenological stages of the crop. A partial cDNA for sbeII in cassava was cloned and used along with a cDNA-specific fragment of sbeI. As the cassava plant aged, the transcriptional activity of the sbeII and sbeI genes in the underground storage roots increased, whereas the activity in other organs remained the same or declined. At 180 days after planting (d.a.p.), levels of sbeII and sbeI transcripts in storage roots were very low, whereas at 360 d.a.p., the levels had increased dramatically. The 360 d.a.p. old storage roots also accumulated gbssII and gbssI transcripts, as well as a longer gbssI transcript, gbssI′. The difference between the gbssI and gbssI′ transcripts was shown to be due to differential splicing, whereby the gbssI′ transcript retained the first three introns. Unexpectedly, expression of sbeII and sbeI in the 360 d.a.p. storage roots exhibited fluctuations during the 24 h cycle, both under the normal light/dark regime and under continuous light or continuous dark conditions.
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| 5. |
- Bellini, C., et al.
(författare)
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Stability of a foreign gene in transgenic Nicotiana tabacum plants during a cycle of dedifferentiation-differentiation
- 1992
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Ingår i: Plant Science. - : Elsevier BV. - 0168-9452 .- 1873-2259. ; 82:2, s. 193-200
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Tidskriftsartikel (refereegranskat)abstract
- Protoplasts of Nicotiana tabacum were transformed with the APH(3’)II gene, which confers kanamycin resistance. Plants resistant to kanamycin were differentiated and 3 of them were chosen at random. These were used to study the stability of the foreign gene after a cycle of dedifferentiation, to produce calli, and differentiation, to produce new plants. The effect of the selective pressure was analyzed by performing dedifferentiation and differentiation in the presence or absence of kanamycin. Inbred plants were also produced from the original transformed plants and used as control. Southern blot analysis of DNA extracted from 66 regenerated plants showed in all cases that no detectable alteration occurred both in gene structure and insertion site. Furthermore the specific activity of the APH(3’)II enzyme was shown to be at high level in all regenerated plants regardless of the fact that they were regenerated in the presence or absence of kanamycin. The results described here are experimental evidence that a hybrid forcing gene is rather stable in a heterologous genome even after dedifferentiation of the transformed plants and differentiation in vitro, i.e. in those conditions known to be correlated with extensive somaclonal variation.
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| 6. |
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| 7. |
- Carol, R. J., et al.
(författare)
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PASTICCINO1 (AtFKBP70) is a nuclear-localised immunophilin required during Arabidopsis thaliana embryogenesis
- 2001
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Ingår i: Plant Science. - : Elsevier BV. - 0168-9452 .- 1873-2259. ; 161:3, s. 527-535
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Tidskriftsartikel (refereegranskat)abstract
- The PASTICCINO1 (PAS1) gene of Arabidopsis thaliana encodes a protein with homology to the FK506-binding protein (FKBP) class of immunophilins. To begin to understand more about the possible function of PAS1, we tested some properties of recombinant PAS1 protein and analysed the expression of the gene in Arabidopsis embryos and cell cultures and in tobacco cells. In pas1-1/+ heterozygote embryos the pas1-1 allele is expressed at very low levels in all cells, but it is misexpressed in the pas1-1 homozygote mutant at the same stage. Anti-PAS1 affinity-purified antibodies recognise a 70 kDa protein from dividing cell cultures of Arabidopsis. In indirect immunofluorescence, the same antibodies label the nuclei of dividing tobacco BY-2 cells. In a protease-coupled assay, recombinant PAS1 protein has low peptidylprolyl cis-trans isomerase (PPIase) activity, which is inhibited by the immunosuppressive drugs FK506 and rapamycin, but not by cyclosporin. PAS1 also binds calmodulin in vitro. This data suggests the importance of the correctly regulated production of functional PAS1 protein, a likely nuclear-localised FKBP, for the correct development of the plant embryo. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.
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| 8. |
- Hakman, Inger, et al.
(författare)
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The development of somatic embryos in tissue-cultures initiated from immature embryos of Picea abies (Norway spruce)
- 1985
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Ingår i: Plant Science. - : Elsevier BV. - 0168-9452 .- 1873-2259. ; 38:1, s. 53-59
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Tidskriftsartikel (refereegranskat)abstract
- Embryos of Picea abies at various developmental stages were cultured on defined media supplemented with 2,4-dichlorophenoxyacetic acid (2,4-D) (10−5 M) and N6-benzyladenine (BA) (5×10−6 M). The immature embryos gave rise to a highly friable and embryogenic callus which could be maintained by subculture and contained polarized and organized structures (somatic embryos) consisting of long highly vacuolated cells at one end (suspensor) and a group of small meristematic cells at the other (embryonal end). These structures closely resembled the early stages of normal zygotic embryogeny. Upon further culture these structures formed a bipolar shoot-root axis with an independent and closed vascular system. In many instances either the shoot or the root meristems failed to differentiate. Embryogenic tissues obtained on agar media could be transferred to liquid media and maintained by subculture for at least 6 months. The development of somatic embryos was observed in the liquid cultures also.
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| 9. |
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| 10. |
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