No description available.

Quarter Horse mares (n=28, 465-612 kg BW, 6-19 yrs of age) were used to investigate the effect of organic selenium (Se) supplementation (Selenosource, Diamond V Mills, Inc. Cedar Rapids, IA (SeM)) and DE manipulation on plasma, muscle, and colostrum Se concentrations, plasma glutathione peroxidase (Gsh-Px) activity, foaling parameters, and physical characteristics in mares and their foals. Mares were arranged in a 2x2 factorial with two levels of nutrition, pasture (100% NRC DE) or pasture plus grain (120% NRC DE) (fed at 0.75% BW (0.63 ppm Se)) and two levels of Se supplementation (0 or 0.3 mg/kg DM) equaling four treatment groups: pasture (P), pasture grain (PG), pasture grain Se (PGS), or pasture Se (PS). Mares were blocked by expected foaling date and randomly assigned to dietary treatment within block. Body condition score (BCS), BW, and rump fat (RF) were observed every 14 d beginning at d 0. Mare and foal plasma and muscle sampling began on d 0 (birth in foals). Plasma continued every 14 d and muscle every 28 d until parturition (d 56 in foals). Upon parturition, foaling parameters consisting of times: water break to birth, birth to placenta expulsion, foal standing, and nursing were recorded. Colostrum quality was determined via refractometer and colostrometer analysis, and placenta weight, foal birth weight, whither and hip height and body length were recorded. Maternal SeM supplementation influenced (P<0.05) mare and foal plasma, muscle and colostrum Se concentrations. Increased maternal DE influenced (P<0.05) mare and foal plasma and foal muscle Se, mare BW, BCS, and RF. However, mare muscle Se was unaffected (P>0.05) by DE. Mare and foal plasma Gsh-Px, foal physical characteristics, and foaling parameters were unaffected by treatment (P>0.05). Greater (P<0.02) colostrum refractometer values (Brix%) for P, PS mares were noted and PGS, P mares had shorter gestational lengths (nutrition x SeM interaction (P<0.05)). These data indicate that maternal DE manipulation and SeM supplementation influences mare and foal Se status, mare BW and colostrum quality (Brix%), but not plasma Gsh-Px activity. Additionally, nutrition and SeM supplementation may affect gestational length. However, despite treatments there was no difference in foaling parameters or foal physical characteristics.

Two days of light irradiance reduced the levels of endogenous indole-3-acetic acid in mungbean (Phaseolus radiatus) hypocotyls. The important enzymes for IAA metabolic degradation are peroxidases and laccase. Peroxidase activity of mungbean hypocotyls was enhanced sevenfold by light. Laccase activity also remarkably increased after illumination. The lignin content in mungbean hypocotyls were enhanced twofold by light treatment. The inhibition of mungbean hypocotyls growth induced by light might be due to the decline of endogenous IAA, which was degraded by cationic peroxidase. The high level of lignin were correlated with the increased anionic peroxidase activity in light-treated tissues.

No description available.

No description available.

Flax (Linum usitatissimum L.) peroxidase cDNAs (FLXPER1--4) were isolated from a lambdagt10 shoot library using probes encoding the amino termini of class III plant peroxidases. These probes were obtained by PCR amplification of the library with lambda primers flanking the EcoRI cloning site, and a mixed oligonucleotide corresponding to the catalytic domain (HFHDCFV) found in secretory plant peroxidases. The transcriptional expressions of FLXPER1 and FLXPER2 appear to be specific to stem based on northern blot analyses. FLXPER1 and FLXPER2 encode acidic peroxidases of calculated isoelectric points (pIc) 4.6 and 4.7, respectively. However, FLXPER1 differs from FLXPER2 in amino acid sequence and in the possession of additional amino acids at its carboxy terminus containing motifs found in membrane-anchored proteins. The FLXPER1 anchoring motifs show striking similarity to those found in a blue copper-type protein (LP18) whose expression in pea (Pisum sativum) has been correlated with lignin deposition. FLXPER3 is expressed in leaf, root, and stein. Partial genomic sequences of FLXPER3 and a highly homologous FLXPER5 were also obtained. FLXPER3 and FLXPER5 do not have the typical class HI plant peroxidase third intron, located within the highly conserved VALSGAHT haem-binding motif. FLXPER3 and FLXPER5 do have, however, an intron downstream of this motif at a location not found in any other class III plant peroxidase gene. FLXPER4 encodes a basic (pIc 8.5) extracellular peroxidase. A modified version of the restriction fragment length polymorphism-coupled domain-directed differential display (RC4D) technique was used to evaluate class III peroxidase transcriptional expression in flax organs. The method revealed the expression of 20 to 30 peroxidase genes in each plant organ examined. It also confirmed the stem-specific nature of FLXPER2 and the ubiquitous character of FLXPER3. FLXPER1 was found in all organs investigated in contrast to results observed by northern b

Class III peroxidases have been identified as secreted proteins involved in plant defense, auxin metabolism, cell wall modification, and regulation of reactive oxygen species. Transcriptome analysis of Arabidopsis has identified many class III peroxidases that respond to aluminum stress. The large number and versatile function of peroxidases make functional characterization of individual peroxidases a challenging task. However, the use of promoter::GUS reporter fusions can help to elucidate the expression pattern of individual peroxidases. To investigate the expression of PER22 and PER73 under aluminum stress in Arabidopsis, single-copy, homozygous, transgenic plants harbouring promoter::GUS reporter fusions were generated through self-pollination and southern blot analyses. Histochemical GUS staining of transgenic lines revealed trichome-specific and vascular-specific expression patterns for PER22 and PER73, respectively. The temporal and spatial expression of PER22 and PER73 suggest that they might be involved in pathogen defense and/or lignification. Further experiments will help define these peroxidase functions under aluminum stress. / Plant Biology

Dissertation (Ph.D.)--Auburn University, 2005. / Abstract. Vita. Includes bibliographic references.

Thesis (Ph. D.)--University of Rhode Island, 2003. / Typescript. Includes bibliographical references (leaves 185-199).

Orientador: Valdecir Farias Ximenes / Banca: Rodrigo Cardoso de Oliveira / Banca: Luiz Carlos da Silva Filho / Resumo: A enzima mieloperoxidase (MPO), proveniente dos neutrófilos e monócitos, é capaz de catalisar a oxidação de íons Cl- e Br- a partir da redução do peróxido de hidrogênio. Os oxidantes formados, ácido hipocloroso (HOCl) e ácido hipobromoso (HOBr) são intensamente reativos e atuam como agentes bactericidas, podendo estar envolvidos em processos deletérios que caracterizam doenças de cunho inflamatório. A determinação da atividade halogenante específica da MPO não é trivial, pois devido ao alto potencial redox da forma ativa composto I (1,16 V), além de Cl- e Br-, ela é capaz de catalisar a oxidação de vários compostos orgânicos pelo mecanismo peroxidásico. Assim, são poucas as metodologias utilizadas até o momento que medem exclusivamente a atividade halogenante. Neste trabalho desenvolvemos uma metodologia para a determinação da atividade halogenante da MPO utilizando a sonda fluorescente dansilglicina (DG), a qual se mostrou insensível a ação peroxidásica da enzima, mas susceptível ao ataque eletrofílico dos ácidos HOCl e HOBr. Os estudos de cinética rápida mostram que a velocidade de reação entre a DG e o HOCl aumenta com a adição de Br-. Foi possível verificar a queda linear na intensidade de fluorescência da DG quando concentrações crescentes de HOCl foram adicionadas ao meio reacional juntamente com uma concentração fixa de Br-. Os mesmos resultados foram obtidos utilizando cromatografia líquida de alta eficiência (HPLC) e, quando acoplado ao espectrômetro de massas, foi p... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The enzyme myeloperoxidase (MPO) is able to catalyze the oxidation of chloride (Cl-) and bromide (Br-) ions from the reduction of hydrogen peroxide. The formed oxidizing agents, hypochlorous acid (HOCl) and hypobromous acid (HOBr) are highly reactive and involved in deleterious inflammatory processes that characterizes many diseases. The determination of the specific halogenating activity of MPO is not trivial, because due to high redox potential of the active form of compound I (MPO-I, 1.16 V), MPO is also capable to catalyze the oxidation of various organic compounds by the peroxidase mechanism. Thus, there are few methods used to date to measure only the halogenating activity. In this work, we developed a methodology for determining the halogenating activity of MPO using the fluorescent probe dansylglycine (DG), which proved insensitive to peroxidase action, but susceptible to electrophilic attack of HOCl and HOBr. The fast kinetics studies show that the reaction rate between DG and HOCl increases with the addition of Br-. It was possible to verify a linear decrease in fluorescence intensity of DG when increasing concentrations of HOCl were added to the reaction medium together with a fixed concentration of Br-. The same results were obtained using high performance lquid chromatography (HPLC) and, when coupled to mass spectrometry, it was possible to identify the product of the reaction, the compound bromo-dansylglycine. The abstraction of Cl- and Br- from the buffer block... (Complete abstract click electronic access below) / Mestre