Silencing of the Phytoene desaturase gene mitigates oxidative stress through the accumulation of free amino acids

Phytoene desaturase (PDS) is a rate-limiting enzyme involved in the biosynthesis of carotenoids, which converts phytoene to zeta-carotene in a two-step desaturation reaction. Transiently blocked carotenogenesis by silencing the PDS gene in Nicotiana benthamiana (NbPDS) using the virus-induced gene silencing (VIGS) technique was used. Silencing of NbPDS induced dwarfism and an albino-type leaf trait in N. benthamiana. The NbPDS-silenced leaves accumulated free amino acids in amounts 9.5-folds greater than those of the GFP-silenced control leaves, but contained only 59.6% of total soluble proteins. When treatment with 10 and 100 μM paraquat was carried out to induce oxidative stress, NbPDS-silenced N. benthamiana demonstrated more resistance at both concentrations compared to the control plants. These data strongly suggest that high concentrations of free amino acids occur because they are inadequately incorporated into proteins of the NbPDS-silenced plants, but reduce injury inflicted by oxidative stress even without the assistance of important antioxidants like carotenoids.

Download Full-text

PSII-9 Free amino acids in pre- and post-rigor muscles from beef cattle under induced oxidative stress by hydrogen peroxide

Journal of Animal Science ◽

10.1093/jas/skab235.579 ◽

2021 ◽

Vol 99 (Supplement_3) ◽

pp. 315-315

Author(s):

Corbin R Fornes ◽

Bethaney M Penrod ◽

Daniel Rivera ◽

Thu Dinh

Keyword(s):

Oxidative Stress ◽

Amino Acids ◽

Hydrogen Peroxide ◽

Free Amino Acids ◽

Free Amino ◽

Fixed Effects ◽

Treatment Time ◽

Block Design ◽

Mass Spectrometry Data ◽

Gas Chromatography Mass Spectrometry

Abstract This study examined the effects of oxidative stress induced by hydrogen peroxide on free amino acids in pre-and post-rigor muscles from beef heifers (n = 18). Cattle were supplemented with ground corn and soybean hulls to 310 to 456 kg of BW while grazing cool and warm-season pastures and were evaluated for preliminary oxidative markers; afterward, they were shipped and finished at a commercial feedlot in Iowa. Animals were blocked into three groups based on prior analysis of oxidative stress markers and two treatments of either 20 mg hydrogen peroxide/kg BW (OX, n = 9) or 10 mL of saline (CON, n = 9) were equally and randomly assigned to animals within each block. On the day before slaughter, the OX and CON treatments were administered intravenously through the jugular vein. Pre-rigor muscles were collected at the neck (splenius) during slaughter; whereas post-rigor muscles were collected at the anterior of the beef loins (longissimus lumborum) at 72 h postmortem. Free amino acids were extracted in phosphate buffer, derivatized by propyl chloroformate, and determined by gas chromatography - mass spectrometry. Data were analyzed as a randomized complete block design with treatment, muscle rigor, and their interaction as fixed effects. Twenty-seven amino acids were quantified and ornithine and glutamine were 0.03 and 2.99 mmole/kg greater in OX muscle than in CON muscle (P = 0.031 and 0.024, respectively). Ten amino acids, such as glutamine and glutamic acid, were greater in pre-rigor muscles (P ≤ 0.003); whereas eleven amino acids were greater in post-rigor muscles, such as ß-aminoisobutyric acid and histidine (P ≤ 0.039). No treatment × time interaction was found (P > 0.069). Both ornithine and glutamine have been reported to reduce oxidative stress. Postmortem metabolism also greatly influences free amino acid concentrations.

Download Full-text

PSII-8 Free amino acids in blood plasma of beef cattle under induced oxidative stress by hydrogen peroxide

Journal of Animal Science ◽

10.1093/jas/skab235.580 ◽

2021 ◽

Vol 99 (Supplement_3) ◽

pp. 315-316

Author(s):

Bethaney M Penrod ◽

Corbin R Fornes ◽

Thu Dinh ◽

Daniel Rivera

Keyword(s):

Oxidative Stress ◽

Amino Acids ◽

Hydrogen Peroxide ◽

Blood Plasma ◽

Repeated Measures ◽

Free Amino Acids ◽

Free Amino ◽

Fixed Effects ◽

Block Design ◽

In Blood Plasma

Abstract This study examined the effects of oxidative stress induced by hydrogen peroxide on free amino acids in blood plasma from beef heifers (n = 18). Cattle were supplemented with ground corn and soybean hulls to 310 to 456 kg of BW while grazing cool and warm-season pastures and were evaluated for preliminary oxidative markers; afterward, they were shipped and finished at a commercial feedlot in Iowa. Animals were blocked into three groups based on principal component analysis of oxidative stress markers and two treatments of either 20 mg hydrogen peroxide/kg BW (OX, n = 9) or 10 mL of saline (CON, n = 9) were equally and randomly assigned to animals within each group. On the day before slaughter, the OX and CON treatments were administered intravenously through the jugular vein. Blood samples were collected immediately before and 90 min after treatment, centrifuged into plasma, aliquoted, snap-frozen in liquid nitrogen, and stored at -80°C. Free amino acids in plasma were derivatized by propyl chloroformate, extracted in isooctane, and determined by gas chromatography – mass spectrometry. The data were analyzed as a randomized complete block design with repeated measures with treatment, time, and their interaction as fixed effects. Twenty-seven amino acids were quantified and sarcosine concentration was 1.5 mM greater in OX plasma than in that of CON (P = 0.064). Leucine, threonine, proline, asparagine, methionine, and α-aminobutyric acid were greater pre-treatment (P ≤ 0.006); whereas cystine was greater at 90 min post-treatment (P = 0.019). Although the effects of hydrogen peroxide injection on free amino acids in blood plasma were minimal, an increase in sarcosine concentration has been reported as a marker of induced oxidative stress.

Download Full-text

Influence of Nitrogen Source on Nitrogen Metabolism in Detached Wheat Heads

Functional Plant Biology ◽

10.1071/pp9780779 ◽

1978 ◽

Vol 5 (6) ◽

pp. 779 ◽

Cited By ~ 1

Author(s):

JW Lee

Keyword(s):

Amino Acids ◽

Ammonium Nitrate ◽

Nitrogen Source ◽

Free Amino Acids ◽

Free Amino ◽

Liquid Culture ◽

Specific Activity ◽

Specific Activities ◽

High Concentrations ◽

Different Parts

Detached wheat heads growing in liquid culture, with either ammonium nitrate or amino acids as the nitrogen source, were exposed to 14CO2 for 1, 2 or 3 h. Examination of the free amino acids in different parts of the heads showed the highest specific activities in glumes. Specific activities were higher in heads cultured on ammonium nitrate than in those cultured on a complete mixture of amino acids. Of the nine amino acids examined, serine had the highest specific activity in grain, glumes and rachis. Proline was present in glumes and rachis at relatively high concentrations but its specific activity was low. Results suggest that the glumes are a significant site of synthesis of carbon skeletons for amino acids in the grain in detached wheat heads.

Download Full-text