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A Aharoni,
L C Keizer,
H J Bouwmeester,
Z Sun,
M Alvarez-Huerta,
H A Verhoeven,
J Blaas,
A M van Houwelingen,
R C De Vos,
H van der Voet,
R C Jansen, M Guis,
J Mol,
R W Davis,
M Schena,
A J van Tunen,
A P O'Connell
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ABSTRACT: Fruit flavor is a result of a complex mixture of numerous compounds. The formation of these compounds is closely correlated with the metabolic changes occurring during fruit maturation. Here, we describe the use of DNA microarrays and appropriate statistical analyses to dissect a complex developmental process. In doing so, we have identified a novel strawberry alcohol acyltransferase (SAAT) gene that plays a crucial role in flavor biogenesis in ripening fruit. Volatile esters are quantitatively and qualitatively the most important compounds providing fruity odors. Biochemical evidence for involvement of the SAAT gene in formation of fruity esters is provided by characterizing the recombinant protein expressed in Escherichia coli. The SAAT enzyme showed maximum activity with aliphatic medium-chain alcohols, whose corresponding esters are major components of strawberry volatiles. The enzyme was capable of utilizing short- and medium-chain, branched, and aromatic acyl-CoA molecules as cosubstrates. The results suggest that the formation of volatile esters in fruit is subject to the availability of acyl-CoA molecules and alcohol substrates and is dictated by the temporal expression pattern of the SAAT gene(s) and substrate specificity of the SAAT enzyme(s).
The Plant Cell 06/2000; 12(5):647-62. · 8.99 Impact Factor
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ABSTRACT: Charentais melons (Cucumis melo cv Reticulatus) are climacteric and undergo extremely rapid ripening. Sixteen cDNAs corresponding to mRNAs whose abundance is ripening regulated were isolated to characterize the changes in gene expression that accompany this very rapid ripening process. Sequence comparisons indicated that eight of these cDNA clones encoded proteins that have been previously characterized, with one corresponding to ACC (1-aminocyclopropane-1-carboxylic acid) oxidase, three to proteins associated with pathogen responses, two to proteins involved in sulfur amino acid biosynthesis, and two having significant homology to a seed storage protein or a yeast secretory protein. The remaining eight cDNA sequences did not reveal significant sequence similarities to previously characterized proteins. The majority of the 16 ripening-regulated cDNAs corresponded to mRNAs that were fruit specific, although three were expressed at low levels in vegetative tissues. When examined in transgenic antisense ACC oxidase melon fruit, three distinct patterns of mRNA accumulation were observed. One group of cDNAs corresponded to mRNAs whose abundance was reduced in transgenic fruit but inducible by ethylene treatment, indicating that these genes are directly regulated by ethylene. A second group of mRNAs was not significantly altered in the transgenic fruit and was unaffected by treatment with ethylene, indicating that these genes are regulated by ethylene-independent developmental cues. The third and largest group of cDNAs showed an unexpected pattern of expression, with levels of mRNA reduced in transgenic fruit and remaining low after exposure to ethylene. Regulation of this third group of genes thus appears to ethylene independent, but may be regulated by developmental cues that require ethylene at a certain stage in fruit development. The results confirm that both ethylene-dependent and ethylene-independent pathways of gene regulation coexist in climacteric fruit.
Plant physiology 04/2000; 122(3):977-83. · 6.53 Impact Factor
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ABSTRACT: Angiomyolipoma (AML) of the liver is an uncommon benign lesion that may be difficult to distinguish clinically, radiographically, and morphologically from hepatocellular carcinoma (HCC).
Fine-needle aspiration biopsies (FNAB) of three AMLs of the liver were compared with FNABs from eight cases of HCC. Immunoperoxidase stains for HMB-45, muscle specific actin, and CAM 5.2 were performed on two cell blocks and one resection of AML.
All three AMLs yielded cellular aspirates. They were composed of clusters of cells with arborizing transgressing endothelium but no peripherally wrapping endothelium. Smooth muscle cells of AML showed fibrillar cytoplasm and indistinct cytoplasmic borders; HCC showed granular cytoplasm and distinct cytoplasmic borders. Extramedullary hematopoiesis was present only in AML. Mitotic figures were seen only in HCC. Intranuclear inclusions, nucleoli, and large, atypical cells were present in both AML and HCC. Fat was seen in only one case of AML and was scant. Immunoperoxidase stains for HMB-45 and smooth muscle actin were positive in AML and negative in adjacent normal liver. CAM 5.2 stain was negative in AML.
The cytologic features seen on FNABs of AML are distinct from those of HCC. Immunoperoxidase stains can aid in the definitive diagnosis on FNAB. It is important to recognize AML on FNAB to allow conservative clinical management.
Cancer 03/1999; 87(1):25-30. · 4.77 Impact Factor
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P Guillén, M Guis,
G Martínez-Reina,
S Colrat,
S Dalmayrac,
C Deswarte,
M Bouzayen,
J P Roustan,
J Fallot,
J C Pech,
A Latché
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ABSTRACT: Eutypine, 4-hydroxy-3-(3-methyl-3-butene-1-ynyl) benzyl aldehyde, is a toxin produced by Eutypa lata, the causal agent of eutypa dieback of grapevines. It has previously been demonstrated that tolerance of some cultivars to this disease was correlated with their capacity to convert eutypine to the corresponding alcohol, eutypinol, which lacks phytotoxicity. We have thus purified to homogeneity a protein from Vigna radiata that exhibited eutypine-reducing activity and have isolated the corresponding cDNA. This encodes an NADPH-dependent reductase of 36 kDa that we have named Vigna radiata eutypine-reducing enzyme (VR-ERE), based on the capacity of a recombinant form of the protein to reduce eutypine into eutypinol. The strongest homologies (86.8%) of VR-ERE at the amino acid level were found with CPRD14, a drought-inducible gene of unknown function, isolated from Vigna unguiculata and with an aromatic alcohol dehydrogenase (71.7%) from Eucalyptus gunnii. Biochemical characterization of VR-ERE revealed that a variety of compounds containing an aldehyde group can act as substrates. However, the highest affinity was observed with 3-substituted benzaldehydes. Expression of a VR-ERE transgene in Vitis vinifera cells cultured in vitro conferred resistance to the toxin. This discovery opens up new biotechnological approaches for the generation of grapevines resistant to eutypa dieback.
The Plant Journal 12/1998; 16(3):335-43. · 6.16 Impact Factor
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ABSTRACT: The role of ethylene in shoot regeneration was investigated using transgenic Cucumis melo plants expressing an antisense 1-aminocyclopropane-1-carboxylate (ACC) oxidase gene. ACC oxidase catalyses the last step
of ethylene biosynthesis. Leaf and cotyledon explants from the transgenic plants exhibited low ACC oxidase activity and ethylene
production, whereas the regeneration capacity of the tissues was greatly enhanced (3.5- and 2.8-fold, respectively) compared
to untransformed control tissues. Addition of ethylene released by 50 or 100 µm 2-chloroethylphosphonic acid dramatically reduced the shoot regeneration rate of the transgenic tissues. The results clearly
demonstrate that ethylene plays an important role in C. melo morphogenesis in vitro.
Plant Cell Reports 03/1998; 17(6):586-589. · 2.27 Impact Factor
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ABSTRACT: The plant hormone ethylene plays a major role in the ripening of climacteric fruit. We have generated transgenic cantaloupe Charentais melons expressing an antisense ACC oxidase gene; ACC oxidase catalyzes the last step of ethylene biosynthesis. Ethylene production of transgenic fruit was < 1% of control untransformed fruit, and the ripening process was blocked both on and off the vine. The antisense phenotype could be reversed by exogenous ethylene treatment. Analysis of antisense ACC oxidase melons indicated that the ripening process includes ethylene-dependent and ethylene-independent pathways. Because the transgenic line we generated displays extended storage life and improved quality, it has a promising potential for commercial development.
Nature Biotechnology 08/1996; 14(7):862-6. · 23.27 Impact Factor
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ABSTRACT: Recent experience has shown that parathyroid adenomas vary in their MR signal intensity, which raises the question of whether the signal intensity is related to different histologic characteristics. In order to address this question, 10 patients who had MR imaging studies (four at 0.35 T, six at 1.5 T) showing large- to medium-sized parathyroid adenomas and who subsequently underwent surgery with histologic proof of the lesion were evaluated. The MR appearance was compared with histologic characteristics. The adenomas were classified into three groups according to the MR appearance: group I, low signal intensity on short TR/TE images, high signal intensity on long TR/TE images (n = 5); group II, low signal intensity on short and long TR/TE images (n = 3); group III, high signal intensity on short and long TR/TE images (n = 2). Histologic analysis revealed that the major features of each group were different. High cellularity without degeneration or fibrosis was observed for all five adenomas from group I. In group II, all three adenomas showed cellular degenerative changes, old hemorrhage with hemosiderin-loaded macrophages, and/or fibrosis. In group III, both adenomas showed evidence of acute hemorrhage without significant degenerative or fibrotic changes. These data suggest that the signal intensity of parathyroid adenomas on T1- and T2-weighted images corresponds at least in part to differences in histologic composition.
American Journal of Roentgenology 11/1989; 153(4):873-6. · 2.78 Impact Factor
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ABSTRACT: Malignant lymphoma is a frequent complication of organ transplantation. It has been suggested that such tumors arise as a result of uncontrolled proliferation of Epstein-Barr virus-infected B lymphocytes in an immunosuppressed host. Although a few cases of posttransplant lymphomas in bone marrow transplantation have been shown to be of donor cell origin, no recipients of solid-organ transplants are known to have developed lymphomas arising from donor cells. In this report, a case of diffuse high-grade lymphoma that apparently arose in the allograft of a renal transplant recipient is described. DNA fingerprinting demonstrated the tumor to be of donor origin; Epstein-Barr sequences were absent. A therapeutic trial consisting of withdrawal of immunosuppressive agents and administration of acyclovir was unsuccessful. These data support the notion that donor cells can undergo malignant transformation in solid-organ transplant recipients, and such tumors need not carry EBV genetic material.
Transplantation 07/1989; 47(6):945-8. · 4.00 Impact Factor
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A. Aharoni,
L.C.P. Keizer,
H.J. Bouwmeester,
Z Sun,
M. Alvarez-Huerta,
H.A. Verhoeven,
J. Blaas,
Houwelingen,
A.M.M.L,
Vos,
R.C.H,
Voet,
R.C. Jansen, M Guis,
R W Davis,
M Schena,
Tunen,
A.J,
A.P. O'Connel
Plant Cell 12: 647-661.
