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1.
Phytopathology ; 108(3): 362-373, 2018 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-29027886

RESUMO

Bois noir (BN) is the most widespread disease of the grapevine yellows complex in the Euro-Mediterranean area. BN is caused by 'Candidatus Phytoplasma solani' (BNp), transmitted from herbaceous plants to grapevine by polyphagous insect vectors. In this study, genetic diversity among BNp strains and their prevalence and possible association with grapevine symptom severity were investigated in a Sangiovese clone organic vineyard in the Chianti Classico area (Tuscany). Field surveys over 2 years revealed a range of symptom severity on grapevine and an increase of BN incidence. A TaqMan allelic discrimination assay detected only tufB type b among BNp strains, suggesting the prevalence of the bindweed-related ecology. Nucleotide sequence analyses of vmp1 and stamp genes identified 12 vmp1 and 16 stamp sequence variants, showing an overall positive selection for such genes. The prevalent genotype was Vm43/St10, reported for the first time in this study and closely related to strains identified only in the French Eastern Pyrenees. BNp strains identified in the examined vineyard and mostly grouped in separate bindweed-related phylogenetic clusters showed statistically significant differences in their distribution in grapevines exhibiting distinct symptom severity. These results suggest the possible occurrence of a range of virulence within BNp strain populations in the Chianti Classico area.


Assuntos
Phytoplasma/classificação , Doenças das Plantas/microbiologia , Vitis/microbiologia , DNA Bacteriano/genética , DNA Bacteriano/metabolismo , Itália , Tipagem Molecular , Filogenia , Phytoplasma/genética
2.
Plant Dis ; 98(12): 1747, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30703907

RESUMO

Grapevine (Vitis vinifera L.) is an economically important crop and can host several different viruses, including those that have to be excluded from certified propagating material in Europe. Among these, the Vitivirus Grapevine virus A (GVA) and the Maculavirus Grapevine fleck virus (GFkV) are phloem-limited viruses that are associated with two different grapevine diseases, Kober stem grooving, belonging to the rugose wood complex, and fleck diseases, respectively. During a survey conducted in 2012 in the former Republic of Macedonia, symptomatic plants with reddening of leaves were collected for laboratory analyses. In this study, grapevine red varieties (Vranec, Francovka, and Pinot noir) from four different localities (Stip, Kavadarci, Valandovo, and Gevgelija) in Macedonia were examined. Thirty-four samples were analyzed by DAS-ELISA using commercially antibodies against Grapevine leafroll associated virus-3 (GLRaV-3). Ten selected samples were processed through DAS-ELISA and molecular assays also for the presence of GVA and GFkV. Total RNA was extracted as previously described (2) and retro-transcribed (RT) using random primers followed by PCR assay with primers GVA-MP (5'-GCCAGAGGTGTTTGAGACAAT-3') and GVA-CPdt (5'-TTTTGTCTTCGTGTGACAACCT-3') (1), which amplified a GVA-specific fragment of 986 bp, and with primers GFkV-U279 (5'-TGGTCCTCGGCCCAGTGAAAAAGTA-3') and GFkV-L630 (5'-GGCCAGGTTGTAGTCGGTGTTGTC-3') (3), which amplified a GFkV-specific region of 315 bp. Results from DAS-ELISA test showed the presence of GLRaV-3 in 21 tested samples and of GVA and GFkV in six and three out of 10 selected samples, respectively. GVA was found in Vranec and Francovka vines sampled in all the locations mentioned before, while GFkV was detected in Vranec and Pinot noir vines, in Stip, Kavadarci, and Gevgelija. These latter results were confirmed by RT-PCR assays; then, four GVA-specific and three GFkV-specific amplicons were sequenced from both directions to get a 3× coverage. For GVA fragment, a primer pair designed in the internal part of the sequence was also used. BLASTn analyses showed that (i) PCR products amplified with GVA-specific primers shared best nucleotide sequence identities, ranging from 91.7 to 93.7%, with GVA isolate at GenBank Accession No. X75433; (ii) PCR products amplified with GFkV-specific primers shared best nucleotide sequence identities, from 92.5 to 94.7%, with GFkV isolate at AJ309022. These evidences reinforced the serological and PCR results indicating that GVA and GFkV were identified in examined grapevine plants in this study. Nucleotide sequences of GVA (KF594432 to 35) and GFkV (KF594429 to 31) were submitted to GenBank. To our knowledge, this is the first report of GVA and GFkV grapevine viruses in the Former Yugoslav Republic of Macedonia. References: (1) J. De Meyer et al. Page 138 in: Extended Abstracts, 13th Meeting of ICVG, Adelaide, 12-17 March 2000. (2) D. J. MacKenzie et al. Plant Dis. 81:222, 1997. (3) B. J. Shi et al. Ann. Appl. Biol. 142:349, 2003.

3.
Plant Dis ; 98(8): 1151, 2014 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30708810

RESUMO

A survey carried out in Georgian vineyards, located in the Khaketi region, in September 2013, showed the presence of vines of the cultivar Chardonnay with typical grapevine yellows (GY) symptoms including leaf discoloration and curling, berry shriveling, and irregular maturation of wood. In the same vineyards, bindweed (Convolvulus arvensis L.) plants showing shoot proliferation and leaf yellowing were found, suggesting the involvement of phytoplasmas in the disease etiology. Total DNA was extracted by a CTAB method from leaf veins of 18 symptomatic and two asymptomatic grapevines, and from four symptomatic and two asymptomatic bindweeds, and analyzed by PCR assays. Moreover, DNA extracted from 'Candidatus Phytoplasma asteris' strain SAY (group 16SrI), 'Ca. P. solani' strain STOL (group 16SrXII), and 'Ca. P. ulmi' strain EY1 (group 16SrV) were used as positive controls. DNA extracted from healthy periwinkle and a reaction mixture without template were employed as negative controls. Nested PCRs targeting the 16S rDNA, carried out using the primer pairs P1/P7 followed by R16F2n/R16R2 (1), produced a band of the expected size (1,250 nt) in all the symptomatic grapevine and bindweed plants, and in the positive controls. No amplification was observed with DNA from asymptomatic plants nor the negative controls. PCR products were sequenced by a commercial sequencing service (Primm, Milan, Italy). The 16S rDNA nucleotide sequences of phytoplasmas identified in all grapevines and in two bindweed samples shared >99.5% sequence identity with 'Ca. P. solani' reference strain STOL (GenBank Accession No. AF248959), and carried identical STOL-unique signature sequence and distinguishing sequence blocks (3). Moreover, nucleotide sequences of phytoplasmas identified in the other two bindweed samples shared >99.6% sequence identity with 'Ca. P. convolvuli' reference strain BY-S57/11 (JN833705) (2). RFLP and phylogenetic analyses confirmed the affiliation of the phytoplasma strains identified in grapevine and bindweed plants in Georgia to the species 'Ca. P. solani' (subgroup 16SrXII-A) and 'Ca. P. convolvuli' (subgroup 16SrXII-H). Representative 16S rDNA nucleotide sequences were deposited in NCBI GenBank website with accession nos. KF996535 and KF996536 ('Ca. P. solani' from grapevine and bindweed, respectively), and KF996537 ('Ca. P. convolvuli'). Future studies will focus on investigating the spread and impact of 'Ca. P. solani'-associated bois noir (BN) in Georgia. In particular, the identification of 'Ca. P. solani' in bindweeds suggested the presence of the insect Hyalesthes obsoletus, a polyphagous cixiidae responsible for BN phytoplasma transmission in vineyards in Europe. Accurate surveys and molecular analyses will be performed for identifying the insect vector(s) of the BN associated phytoplasma strains in Georgia. Additional studies will be performed to study the spread and impact of 'Ca. P. convolvuli,' identified only in Italy, Germany, Serbia, and Bosnia and Herzegovina (2), throughout the Caucasian countries. References: (1) I.-M. Lee et al. Int. J. Syst. Bacteriol. 48:1153, 1998. (2) M. Martini et al. Int. J. Syst. Evol. Microbiol. 62:2910, 2013. (3) F. Quaglino et al. Int. J. Syst. Evol. Microbiol. 63:2879, 2013.

4.
Plant Dis ; 97(11): 1505, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30708465

RESUMO

During a survey carried out in Jordanian vineyards in August and October 2012, grapevine (Vitis vinifera L.) plants showing typical grapevine yellows (GY) disease symptoms, including leaf discoloration and curling, berry shriveling, and irregular maturation of wood, were observed. In the same vineyards, bindweed (Convolvulus arvensis L.) plants showing stunting and leaf chromatic alteration were found, suggesting the involvement of phytoplasmas in the disease etiology. Using a CTAB method, total DNA was extracted from leaf veins of 25 symptomatic and two asymptomatic grapevines, and from five symptomatic and two asymptomatic bindweeds for PCR analysis. DNAs from periwinkle (Catharanthus roseus (L.) G. Don) plants infected by 'Ca. Phytoplasma asteris' strain SAY (group 16SrI), 'Ca. Phytoplasma solani' strain STOL (group 16SrXII), and 'Ca. Phytoplasma ulmi' strain EY1 (group 16SrV), were used as positive controls. DNAs from healthy periwinkle and reactions without template DNA were employed as negative controls. 16S rDNA nested PCRs, carried out using the primer pairs P1/P7, followed by R16F2n/R16R2 (1), yielded an amplicon of the expected size (1,250-bp) in three grapevine and in five bindweed samples, and in positive controls. Amplicons were not produced with DNA from 22 symptomatic grapevines (probably because samples were collected late in the growing season and phytoplasma distribution in plants was non-uniform [2]); nor from asymptomatic plants and negative controls. PCR products were sequenced by commercial services in Italy (Primm, Milan) and Korea (Macrogen Inc., Soul). Representative 16S rDNA nucleotide sequences were deposited in NCBI GenBank with accessions KC835139 (from grapevine) and KC835140 (from bindweed). The 16S rDNA nucleotide sequences of phytoplasmas identified in grapevine and bindweed in Jordan shared >99.5% sequence identity with 'Ca. Phytoplasma solani' reference strain STOL (AF248959), and carried identical STOL-unique signature sequences and distinguishing sequence blocks (3). Phylogenetic and in silico RFLP analyses confirmed the affiliation of phytoplasma strains identified in grapevine and bindweed in Jordan to the species 'Ca. Phytoplasma solani' (subgroup 16SrXII-A), opening an avenue to future studies on the dissemination and impact of Bois noir (BN) in Jordan. These studies may add new information about BN, previously reported in neighboring countries (4). Further studies will investigate the role of Hyalesthes obsoletus Signoret, a polyphagous Cixiidae responsible for the BN phytoplasma transmission in Europe, and other possible insect vector(s) in the BN spread in Jordan. References: (1) I.-M. Lee et al. Int. J. Syst. Bact. 48:1153, 1998. (2) F. E. Constable et al. Plant Pathol. 52:267, 2003. (3) F. Quaglino et al. Int. J. Syst. Evol. Microb. 63:2879. (4) E. Choueiri et al. Plant Dis. 86:697, 2002.

5.
Folia Microbiol (Praha) ; 55(3): 251-7, 2010 May.
Artigo em Inglês | MEDLINE | ID: mdl-20526838

RESUMO

During a survey on grapevine yellows disease complex in vineyards of Lombardy region (northern Italy), phytoplasmas associated with Flavescence dorée disease were identified in symptomatic grapevines. Polymerase chain reaction and restriction fragment length polymorphism (RFLP) analyses of 16S rDNA revealed the prevalence of phytoplasmal subgroup 16SrV-D. Bioinformatic analyses of nucleotide sequences of rplV and rpsC genes, amplified from 16SrV-D phytoplasma infected grapevines and cloned, underscored the presence of five confirmed rpsC single nucleotide polymorphism (SNP) lineages, determined by different combination of SNPs at nucleotide positions 29, 365, 680, and 720 of rpsC gene. Virtual and actual RFLP analyses with the enzyme TaqI validated the presence of these SNPs. Co-infections by up to four distinct rpsC SNP lineages of 16SrV-D phytoplasma were found in grapevines. These results could open new perspectives for the study of the ecology and the epidemiology of Flavescence dorée.


Assuntos
Proteínas de Bactérias/genética , Phytoplasma/classificação , Phytoplasma/isolamento & purificação , Doenças das Plantas/microbiologia , Polimorfismo de Nucleotídeo Único , Proteínas Ribossômicas/genética , Vitis/microbiologia , Análise por Conglomerados , Impressões Digitais de DNA , DNA Bacteriano/química , DNA Bacteriano/genética , DNA Ribossômico/genética , Itália , Dados de Sequência Molecular , Filogenia , Phytoplasma/genética , Reação em Cadeia da Polimerase , Polimorfismo de Fragmento de Restrição , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Homologia de Sequência
6.
J Econ Entomol ; 100(4): 1047-52, 2007 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-17849850

RESUMO

Plum pox virus (family Potyviridae, genus Potyvirus, PPV) is one of the most important viral pathogens of plants in the genus Prunus, particularly Prunus persica L. The role of the Myzus persicae (Sulzer) (Hemiptera: Aphididae) as a vector of PPV-M, and its role in spreading PPV-M, was investigated. PPV-M-infected peach trees were used as inoculum sources, and transmission to 15 herbaceous species commonly present in and around peach orchards was evaluated. The presence of PPV-M in secondary hosts after aphid transmission was verified by reverse transcription-polymerase chain reaction tests. The results indicate that Saponaria ocymoides L., Pisum sativum L., Trifolium repens L., Trifolium pratense L., Lepidium sativum L., Matricaria chamomilla L., Centaurea cyanus L., Bellis perennis L., Papaver rhoeas L., and Zinnia elegans L. became infected. Although Lupinus polyphyllus Lindley, Taraxacum officinale L., Achillea millefolium L., Amaranthus retroflexus L., and Linum rubrum L. did not become infected, they are hosts of M. persicae. Among the 10 positive species that were infected, the species most common in peach orchards, T. pratense, T. repens, B. perennis, and M. chamomilla, were used as source plants for the transmission studies to the peach tree. Our study reveals the ability of M. persicae to transmit PPV-M from herbaceous hosts to peach trees, describes PPV-M symptoms in herbaceous species, and discusses the role of M. persicae and its hosts as a source of PPV-M in peach orchards.


Assuntos
Afídeos/virologia , Insetos Vetores/virologia , Doenças das Plantas/virologia , Vírus Eruptivo da Ameixa/fisiologia , Prunus/virologia , Animais , Bioensaio , Transmissão de Doença Infecciosa , Vírus Eruptivo da Ameixa/crescimento & desenvolvimento , Prunus/anatomia & histologia , Reação em Cadeia da Polimerase Via Transcriptase Reversa
7.
Mol Cell Probes ; 16(3): 197-208, 2002 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-12144771

RESUMO

Flavescence dorée is a devastating disease of grapevine widespread in several countries in EU such as France, Italy and Spain. Genetic variability among 17 Italian and 3 French FD strains was investigated by RFLP analyses based on a fragment of the ribosomal protein operon and on the non-ribosomal DNA fragment FD9. RFLP analysis of the PCR amplified ribosomal protein fragment, coding for the 3' end of rpl22 and the entire rps3 genes, differentiated 4 rp-subgroups among the FD strains and 4 subgroups among the reference strains belonging to elm yellows group (16SrV). Sequencing and phylogenetic analysis of the same ribosomal protein DNA fragment validated the delineation of 4 distinct FD strain types derived by RFLP analyses. The results supported the differentiation based on analysis of the non-ribosomal DNA fragment FD9. The phylogenetic analysis further revealed relationships and a probable evolutionary trend among the FD strains and the other representatives of elm yellows group. All the FD strains together with the reference strains ALY, RuS and JWB formed a cluster very well distinct from the EY/ULW cluster. Moreover, ALY was shown to be more closely related to three FD strain types: the Lombardia/Piemonte, the French FD70, and the French FD88/Italian FD-D strain clusters.


Assuntos
Variação Genética , Mycoplasma/genética , Doenças das Plantas/microbiologia , Vitis/microbiologia , DNA Bacteriano/análise , DNA Ribossômico/genética , França , Itália , Dados de Sequência Molecular , Mycoplasma/classificação , Óperon , Filogenia , Polimorfismo de Fragmento de Restrição , Alinhamento de Sequência
8.
Plant Cell Physiol ; 42(4): 441-5, 2001 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-11333316

RESUMO

In vivo phosphorylation of PEPC in Egeria densa was studied using plants at high temperature and in light, and plants kept at low temperature and in light. The isoform induced by high temperature and light was more phosphorylated in the light. Changes in kinetic and regulatory properties correlated with changes in the phosphorylation state of PEPC.


Assuntos
Liliaceae/enzimologia , Fosfoenolpiruvato Carboxilase/metabolismo , Escuridão , Isoenzimas/metabolismo , Cinética , Luz , Fosforilação , Temperatura , Termodinâmica
9.
FEBS Lett ; 490(1-2): 1-6, 2001 Feb 09.
Artigo em Inglês | MEDLINE | ID: mdl-11172800

RESUMO

NADP-malic enzyme (NADP-ME) is a widely distributed enzyme that catalyzes the oxidative decarboxylation of L-malate. Photosynthetic NADP-MEs are found in C4 bundle sheath chloroplasts and in the cytosol of CAM plants, while non-photosynthetic NADP-MEs are either plastidic or cytosolic in various plants. We propose a classification of plant NADP-MEs based on their physiological function and localization and we describe recent advances in the characterization of each isoform. Based on the alignment of amino acid sequences of plant NADP-MEs, we identify putative binding sites for the substrates and analyze the phylogenetic origin of each isoform, revealing several features of the molecular evolution of this ubiquitous enzyme.


Assuntos
Malato Desidrogenase/química , Plantas/enzimologia , Sequência de Aminoácidos , Sítios de Ligação , Evolução Molecular , Cinética , Malato Desidrogenase/classificação , Dados de Sequência Molecular , Filogenia , Isoformas de Proteínas
10.
Plant Physiol ; 123(4): 1611-22, 2000 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-10938377

RESUMO

The expression of phosphoenolpyruvate carboxylase (PEPC) and NADP-malic enzyme (NADP-ME) in Egeria densa leaves was studied under low temperature and light (LTL) following incubation under high temperature and light (HTL), conditions previously shown to induce high and low CO(2) compensation points, respectively. Transfer from LTL to HTL conditions induced increases in the activities and amounts of both enzymes. One NADP-ME isoform was observed in induced and uninduced samples. Two isoforms of PEPC were expressed, with the lower M(r) isoform being induced by HTL. NADP-ME showed properties similar to those of the isoform in C(3) species. The inducible PEPC isoform has a low K(m) for both substrates. PEPC kinetic and regulatory properties (V(max) and K(m) for phosphoenolpyruvate, and I(50) for L-malate) are different in samples taken in the dark from those in the light, indicating that some modification of PEPC may be occurring during the day. Finally, abscisic acid induced the expression of PEPC and NADP-ME in a manner similar to temperature induction, except that the activities of both PEPC isoforms were increased. A different signaling system may exist in this species in response to high temperature or abscisic acid, both of which induce changes in photosynthetic metabolism.


Assuntos
Dióxido de Carbono/metabolismo , Magnoliopsida/metabolismo , Malato Desidrogenase/metabolismo , Fotossíntese/fisiologia , Ácido Abscísico/metabolismo , Ácido Abscísico/farmacologia , Southern Blotting , Western Blotting , DNA de Plantas/análise , Isoenzimas/metabolismo , Luz , Magnoliopsida/enzimologia , Malatos/farmacologia , Peso Molecular , Fosfoenolpiruvato Carboxilase/química , Fosfoenolpiruvato Carboxilase/metabolismo , Folhas de Planta/enzimologia , Folhas de Planta/metabolismo , Folhas de Planta/ultraestrutura , Temperatura
11.
Braz J Med Biol Res ; 32(10): 1187-93, 1999 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-10510253

RESUMO

The induction of nicotinamide adenine dinucleotide phosphate-malic enzyme (NADP-ME) in etiolated maize (Zea mays) seedlings by UV-B and UV-A radiation, and different levels of photosynthetically active radiation (PAR, 400-700 nm) was investigated by measuring changes in activity, protein quantity and RNA levels as a function of intensity and duration of exposure to the different radiations. Under low levels of PAR, exposure to UV-B radiation but not UV-A radiation for 6 to 24 h caused a marked increase in the enzyme levels similar to that observed under high PAR in the absence of UV-B. UV-B treatment of green leaves following a 12-h dark period also caused an increase in NADP-ME expression. Exposure to UV-B radiation for only 5 min resulted in a rapid increase of the enzyme, followed by a more gradual rise with longer exposure up to 6 h. Low levels of red light for 5 min or 6 h were also effective in inducing NADP-ME activity equivalent to that obtained with UV-B radiation. A 5-min exposure to far-red light following UV-B or red light treatment reversed the induction of NADP-ME, and this effect could be eliminated by further treatment with UV-B or red light. These results indicate that physiological levels of UV-B radiation can have a positive effect on the induction of this photosynthetic enzyme. The reducing power and pyruvate generated by the activity of NADP-ME may be used for respiration, in cellular repair processes and as substrates for fatty acid synthesis required for membrane repair.


Assuntos
Malato Desidrogenase/efeitos da radiação , Fotossíntese/efeitos da radiação , Raios Ultravioleta , Zea mays/efeitos da radiação , Indução Enzimática , Malato Desidrogenase/metabolismo , RNA/metabolismo , RNA/efeitos da radiação , Fatores de Tempo , Zea mays/enzimologia
12.
Braz. j. med. biol. res ; 32(10): 1187-93, Oct. 1999. tab
Artigo em Inglês | LILACS | ID: lil-252266

RESUMO

The induction of nicotinamide adenine dinucleotide phosphate-malic enzyme (NADP-ME) in etiolated maize (Zea mays) seedlings by UV-B and UV-A radiation, and different levels of photosynthetically active radiation (PAR, 400-700 nm) was investigated by measuring changes in activity, protein quantity and RNA levels as a function of intensity and duration of exposure to the different radiations. Under low levels of PAR, exposure to UV-B radiation but not UV-A radiation for 6 to 24 h caused a marked increase in the enzyme levels similar to that observed under high PAR in the absence of UV-B. UV-B treatment of green leaves following a 12-h dark period also caused an increase in NADP-ME expression. Exposure to UV-B radiation for only 5 min resulted in a rapid increase of the enzyme, followed by a more gradual rise with longer exposure up to 6 h. Low levels of red light for 5 min or 6 h were also effective in inducing NADP-ME activity equivalent to that obtained with UV-B radiation. A 5-min exposure to far-red light following UV-B or red light treatment reversed the induction of NADP-ME, and this effect could be eliminated by further treatment with UV-B or red light. These results indicate that physiological levels of UV-B radiation can have a positive effect on the induction of this photosynthetic enzyme. The reducing power and pyruvate generated by the activity of NADP-ME may be used for respiration, in cellular repair processes and as substrates for fatty acid synthesis required for membrane repair


Assuntos
Malato Desidrogenase/metabolismo , Fotossíntese/efeitos da radiação , Raios Ultravioleta , Zea mays/enzimologia , Zea mays/efeitos da radiação , Fatores de Tempo
13.
J Photochem Photobiol B ; 48(2-3): 200-9, 1999 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-10343405

RESUMO

The effects of UV-B radiation on growth, photosynthesis, UV-B-absorbing compounds and NADP-malic enzyme have been examined in different cultivars of Phaseolous vulgaris L. grown under 1 and 12 mM nitrogen. Low nitrogen nutrition reduces chlorophyll and soluble protein contents in the leaves and thus the photosynthesis rate and dry-matter accumulation. Chlorophyll, soluble protein and Rubisco contents and photosynthesis rate are not significantly altered by ambient levels of UV-B radiation (17 microW m-2, 290-320 nm, 4 h/day for one week). Comparative studies show that under high nitrogen, UV-B radiation slightly enhances leaf expansion and dry-matter accumulation in cultivar Pinto, but inhibits these parameters in Vilmorin. These results suggest that the UV-B effect on growth is mediated through leaf expansion, which is particularly sensitive to UV-B, and that Pinto is more tolerant than Vilmorin. The effect of UV-B radiation on UV-B-absorbing compounds and on NADP-malic enzyme (NADP-ME) activity is also examined. Both UV-B radiation and low-nitrogen nutrition enhance the content of UV-B-absorbing compounds, and among the three cultivars used, Pinto exhibits the highest increases and Arroz the lowest. The same trend is observed for the specific activity and content of NADP-ME. On a leaf-area basis, the amount of UV-B-absorbing compounds is highly correlated with the enzyme activity (r2 = 0.83), suggesting that NADP-ME plays a key role in biosynthesis of these compounds. Furthermore, the higher sensitivity of Vilmorin than Pinto to UV-B radiation appears to be related to the activity of NADP-ME and the capacity of the plants to accumulate UV-B-absorbing compounds.


Assuntos
Fabaceae/efeitos da radiação , Plantas Medicinais , Raios Ultravioleta , Dióxido de Carbono , Clorofila , Fabaceae/enzimologia , Fabaceae/crescimento & desenvolvimento , Fabaceae/fisiologia , Malato Desidrogenase/metabolismo , Malato Desidrogenase/efeitos da radiação , Nitrogênio/metabolismo , Fotossíntese/efeitos da radiação , Folhas de Planta/metabolismo , Proteínas de Plantas/metabolismo , Ribulose-Bifosfato Carboxilase/metabolismo
14.
Plant Physiol ; 117(3): 733-44, 1998 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-9662516

RESUMO

NADP-malic enzyme (NADP-ME, EC 1.1.1.40), a key enzyme in C4 photosynthesis, provides CO2 to the bundle-sheath chloroplasts, where it is fixed by ribulose-1,5-bisphosphate carboxylase/oxygenase. We characterized the isoform pattern of NADP-ME in different photosynthetic species of Flaveria (C3, C3-C4 intermediate, C4-like, C4) based on sucrose density gradient centrifugation and isoelectric focusing of the native protein, western-blot analysis of the denatured protein, and in situ immunolocalization with antibody against the 62-kD C4 isoform of maize. A 72-kD isoform, present to varying degrees in all species examined, is predominant in leaves of C3 Flaveria spp. and is also present in stem and root tissue. By immunolabeling, NADP-ME was found to be mostly localized in the upper palisade mesophyll chloroplasts of C3 photosynthetic tissue. Two other isoforms of the enzyme, with molecular masses of 62 and 64 kD, occur in leaves of certain intermediates having C4 cycle activity. The 62-kD isoform, which is the predominant highly active form in the C4 species, is localized in bundle-sheath chloroplasts. Among Flaveria spp. there is a 72-kD constitutive form, a 64-kD form that may have appeared during evolution of C4 metabolism, and a 62-kD form that is necessary for the complete functioning of C4 photosynthesis.

15.
Biochim Biophys Acta ; 1383(2): 245-52, 1998 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-9602140

RESUMO

The different aggregational states of maize and wheat NADP-malic enzyme as affected by pH, temperature and various metabolites have been studied by the combined use of intersubunit crosslinking and denaturing polyacrylamide gel electrophoresis. The association/dissociation equilibrium is a pH-dependent process: pH values above 8.0 promote the tetramer formation, while lowering the pH shifts the equilibria towards dimers and monomers. Below pH 6.0, most molecules exist as monomers. In the same way, the temperature governs the equilibria between the different oligomeric states. As the temperature is lowered from 42 to 0 degrees C, a progressive dissociation into dimers and monomers is observed. Excess enthalpies are negative in all cases, but the overall process demands an input of Gibb's free energy. Consequently, the protein dissociation is an entropy-driven process. The presence of Mg2+ or glycerol induces aggregation in both enzymes, while increasing the ionic strength produces the opposite effect. The results suggest that changes in the equilibria between monomer, dimer and tetramer of NADP-malic enzyme could be the molecular basis for an effective regulation of the enzyme activity in vivo.


Assuntos
Malato Desidrogenase/química , Triticum/enzimologia , Zea mays/enzimologia , Reagentes de Ligações Cruzadas , Dimerização
16.
Farmaco Sci ; 42(5): 319-23, 1987 May.
Artigo em Inglês | MEDLINE | ID: mdl-3609290

RESUMO

A very high molecular weight form of urokinase, of about 100,000 D (VHMr-UK), was isolated from human urine in trace amounts as compared to the well characterized two forms of urokinase, HMr-UK (Mr of about 50,000) and LMr-UK (Mr of about 30,000). This form was demonstrated to be a dimer of HMr-UK, in which no covalent bond is involved, on the basis of the following evidence: by SDS electrophoresis it is dissociated, to the 50,000 D form; by electrophoresis in SDS under reducing conditions it is dissociated, as HMr-UK, to two polypeptide chains of about 30,000 and 20,000 D; by short heating at pH 5 it is quantitatively converted to the 50,000 D form; the kinetic constants towards the alpha-carbobenzoxy-L-lysine-p-nitro-phenylester substrate are the same for HMr-UK and VHMr-UK.


Assuntos
Ativador de Plasminogênio Tipo Uroquinase/urina , Cromatografia em Gel , Eletroforese em Gel de Poliacrilamida , Humanos , Cinética , Peso Molecular , Ribonuclease Pancreático/metabolismo , Dodecilsulfato de Sódio
17.
Ital J Biochem ; 24(3-4): 188-98, 1975.
Artigo em Inglês | MEDLINE | ID: mdl-1213874

RESUMO

Affinity chromatography has led to the extraction of a trypsin inhibitor from urines of pregnant women, with a recovery of about 85%. The inhibitor obtained by this method is fairly pure, but heterogeneous, according to several criteria. The heterogeneity is not the result of the extraction procedure, but it seems to pre-exist in the urine itself.


Assuntos
Gravidez , Inibidores da Tripsina/urina , Cromatografia de Afinidade , Feminino , Humanos , Inibidores da Tripsina/isolamento & purificação
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