Eyespot-dependent determination of the phototactic sign inChlamydomonas reinhardtii

The biflagellate green algaChlamydomonas reinhardtiiexhibits both positive and negative phototaxis to inhabit areas with proper light conditions. It has been shown that treatment of cells with reactive oxygen species (ROS) reagents biases the phototactic sign to positive, whereas that with ROS scavengers biases it to negative. Taking advantage of this property, we isolated a mutant,lts1-211, which displays a reduction-oxidation (redox) dependent phototactic sign opposite to that of the wild type. This mutant has a single amino acid substitution in phytoene synthase, an enzyme that functions in the carotenoid-biosynthesis pathway. The eyespot contains large amounts of carotenoids and is crucial for phototaxis. Mostlts1-211cells have no detectable eyespot and reduced carotenoid levels. Interestingly, the reversed phototactic-sign phenotype oflts1-211is shared by other eyespot-less mutants. In addition, we directly showed that the cell body acts as a convex lens. The lens effect of the cell body condenses the light coming from the rear onto the photoreceptor in the absence of carotenoid layers, which can account for the reversed-phototactic-sign phenotype of the mutants. These results suggest that light-shielding property of the eyespot is essential for determination of phototactic sign.

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Genetic Characterization of the Carotenoid Biosynthetic Pathway in Methylobacterium extorquens AM1 and Isolation of a Colorless Mutant

Applied and Environmental Microbiology ◽

10.1128/aem.69.12.7563-7566.2003 ◽

2003 ◽

Vol 69 (12) ◽

pp. 7563-7566 ◽

Cited By ~ 29

Author(s):

Stephen J. Van Dien ◽

Christopher J. Marx ◽

Brooke N. O'Brien ◽

Mary E. Lidstrom

Keyword(s):

Biosynthetic Pathway ◽

Genetic Characterization ◽

Carotenoid Biosynthesis ◽

Biosynthesis Pathway ◽

Wild Type ◽

Methylobacterium Extorquens ◽

Growth Properties ◽

Carotenoid Biosynthesis Pathway ◽

Free Strain

ABSTRACT Genomic searches were used to reconstruct the putative carotenoid biosynthesis pathway in the pink-pigmented facultative methylotroph Methylobacterium extorquens AM1. Four genes for putative phytoene desaturases were identified. A colorless mutant was obtained by transposon mutagenesis, and the insertion was shown to be in one of the putative phytoene desaturase genes. Mutations in the other three did not affect color. The tetracycline marker was removed from the original transposon mutant, resulting in a pigment-free strain with wild-type growth properties useful as a tool for future experiments.

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SIR-2.1 integrates metabolic homeostasis with the reproductive neuromuscular excitability in early aging male Caenorhabditis elegans

eLife ◽

10.7554/elife.01730 ◽

2014 ◽

Vol 3 ◽

Cited By ~ 9

Author(s):

Xiaoyan Guo ◽

L René García

Keyword(s):

Mating Behavior ◽

Vas Deferens ◽

Lipid Synthesis ◽

Oxygen Species ◽

Wild Type ◽

Compensatory Response ◽

C Elegans ◽

Catabolic Enzymes ◽

Neuromuscular Excitability ◽

Ros Scavengers

The decline of aging C. elegans male’s mating behavior is correlated with the increased excitability of the cholinergic circuitry that executes copulation. In this study, we show that the mating circuits’ functional durability depends on the metabolic regulator SIR-2.1, a NAD+-dependent histone deacetylase. Aging sir-2.1(0) males display accelerated mating behavior decline due to premature hyperexcitability of cholinergic circuits used for intromission and ejaculation. In sir-2.1(0) males, the hypercontraction of the spicule-associated muscles pinch the vas deferens opening, thus blocking sperm release. The hyperexcitability is aggravated by reactive oxygen species (ROS). Our genetic, pharmacological, and behavioral analyses suggest that in sir-2.1(0) and older wild-type males, enhanced catabolic enzymes expression, coupled with the reduced expression of ROS-scavengers contribute to the behavioral decline. However, as a compensatory response to reduce altered catabolism/ROS production, anabolic enzymes expression levels are also increased, resulting in higher gluconeogenesis and lipid synthesis.

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Characterizing an engineered carotenoid-producing yeast as an anti-stress chassis for building cell factories

Microbial Cell Factories ◽

10.1186/s12934-019-1205-y ◽

2019 ◽

Vol 18 (1) ◽

Cited By ~ 1

Author(s):

Hsien-Lin Liu ◽

Jui-Jen Chang ◽

Caroline Thia ◽

Yu-Ju Lin ◽

Shou-Chen Lo ◽

...

Keyword(s):

Ethanol Tolerance ◽

Cost Effective ◽

Carotenoid Biosynthesis ◽

Wild Type ◽

Cell Factories ◽

Natural Medicine ◽

Engineered Yeast ◽

Radical Removal ◽

Carotenoid Biosynthesis Pathway ◽

Tolerance To Ethanol

Abstract Background A microorganism engineered for non-native tasks may suffer stresses it never met before. Therefore, we examined whether a Kluyveromyces marxianus strain engineered with a carotenoid biosynthesis pathway can serve as an anti-stress chassis for building cell factories. Results Carotenoids, a family of antioxidants, are valuable natural products with high commercial potential. We showed that the free radical removal ability of carotenoids can confer the engineered host with a higher tolerance to ethanol, so that it can produce more bio-ethanol than the wild type. Moreover, we found that this engineered strain has improved tolerance to other toxic effects including furfurals, heavy metals such as arsenate (biomass contaminant) and isobutanol (end product). Furthermore, the enhanced ethanol tolerance of the host can be applied to bioconversion of a natural medicine that needs to use ethanol as the delivery solvent of hydrophobic precursors. The result suggested that the engineered yeast showed enhanced tolerance to ethanol-dissolved hydrophobic 10-deacetylbaccatin III, which is considered a sustainable precursor for paclitaxel (taxol) bioconversion. Conclusions The stress tolerances of the engineered yeast strain showed tolerance to several toxins, so it may serve as a chassis for cell factories to produce target products, and the co-production of carotenoids may make the biorefinary more cost-effective.

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Differential Response of Several Carotenoid Biosynthesis Inhibitors in Mixtures with Atrazine

Weed Technology ◽

10.1614/wt-06-133.1 ◽

2007 ◽

Vol 21 (4) ◽

pp. 947-953 ◽

Cited By ~ 16

Author(s):

Gregory R. Armel ◽

Patrick L. Rardon ◽

Michael C. McComrick ◽

Nancy M. Ferry

Keyword(s):

Enzyme Inhibitor ◽

D1 Protein ◽

Carotenoid Biosynthesis ◽

Phytoene Desaturase ◽

Oxygen Species ◽

Biosynthesis Pathway ◽

Giant Foxtail ◽

Lycopene Cyclase ◽

Carotenoid Biosynthesis Pathway ◽

Singlet Oxygen Species

Greenhouse studies were conducted in 2003 at the Stine–Haskell Research Center to determine whether herbicide inhibitors of six specific sites in the carotenoid biosynthesis pathway would elicit synergistic responses when applied postemergence (POST) in combination with the photosystem II (PSII) inhibitor atrazine. Based on data analysis with the Isobole method, synergistic responses were observed on red morningglory, common cocklebur, and giant foxtail when atrazine was applied in mixtures with the deoxy-D-xylulose-5-phosphate reductoisomerase (DOXP reductoisomerase) inhibitor fosmidomycin, thep-hydroxyphenylpyruvate dioxygenase (HPPD) inhibitor mesotrione, and the DuPont proprietary zeta-carotene desaturase (ZDS) inhibitor DFPC. Clomazone (its metabolite ketoclomazone is the actual enzyme inhibitor), an inhibitor of 1-deoxy-D-xylulose-5-phosphate synthatase (DOXP synthase), provided synergistic responses on red morningglory, but antagonistic responses on both common cocklebur and giant foxtail when applied in mixtures with atrazine. Combinations of the lycopene cyclase (LC) inhibitor, CPTA, with atrazine produced synergistic responses on both common cocklebur and giant foxtail but were antagonistic on red morningglory. Norflurazon, a phytoene desaturase (PDS) inhibitor, applied in mixtures with atrazine provided synergistic responses on red morningglory, antagonistic responses on giant foxtail, and independent responses on common cocklebur. Because carotenoids have been determined to play a key role in quenching singlet oxygen species in the chloroplast and also assist in the maintenance of the D1 protein in PSII, this might help explain the synergistic responses with atrazine observed in our studies.

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A Single Amino Acid Insertion in LCYB2 Deflects Carotenoid Biosynthesis in Red Carrot

10.21203/rs.3.rs-582415/v1 ◽

2021 ◽

Author(s):

Hye Sun Cho ◽

Seung Hee Jo ◽

Hyun Ji Park ◽

Areum Lee ◽

Haemyeong Jung ◽

...

Keyword(s):

Amino Acid ◽

Vitamin A ◽

Molecular Basis ◽

Carotenoid Biosynthesis ◽

Genetic Network ◽

Single Amino Acid ◽

Biosynthesis Pathway ◽

Carotenoid Production ◽

Amino Acid Insertion ◽

Carotenoid Biosynthesis Pathway

Abstract Carotenoids are phytochemicals that are precursors of vitamin A and effective antioxidants, required for human health. The mechanisms and underlying genetic network responsible for regulating carotenoid production in plants, however, is poorly understood, despite the carotenoid biosynthesis pathway being known. We found that a single amino acid insertion in lycopene β-cyclase2 (LCYB2) caused catalytic failure, possibly due to a flux down of lycopene to the carotenoids which may be the molecular basis for the color of red carrot roots.

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Unique Cellular and Biochemical Features of Human Mitochondrial Peroxiredoxin 3 Establish the Molecular Basis for Its Specific Reaction with Thiostrepton

Antioxidants ◽

10.3390/antiox10020150 ◽

2021 ◽

Vol 10 (2) ◽

pp. 150

Author(s):

Kimberly J. Nelson ◽

Terri Messier ◽

Stephanie Milczarek ◽

Alexis Saaman ◽

Stacie Beuschel ◽

...

Keyword(s):

Oxygen Species ◽

Mitochondrial Reactive Oxygen Species ◽

Wild Type ◽

Cellular Models ◽

Chemotherapeutic Approach ◽

Promising Target ◽

Redox Responsive ◽

Catalytic Cysteine ◽

Increased Sensitivity ◽

Peroxiredoxin 3

A central hallmark of tumorigenesis is metabolic alterations that increase mitochondrial reactive oxygen species (mROS). In response, cancer cells upregulate their antioxidant capacity and redox-responsive signaling pathways. A promising chemotherapeutic approach is to increase ROS to levels incompatible with tumor cell survival. Mitochondrial peroxiredoxin 3 (PRX3) plays a significant role in detoxifying hydrogen peroxide (H2O2). PRX3 is a molecular target of thiostrepton (TS), a natural product and FDA-approved antibiotic. TS inactivates PRX3 by covalently adducting its two catalytic cysteine residues and crosslinking the homodimer. Using cellular models of malignant mesothelioma, we show here that PRX3 expression and mROS levels in cells correlate with sensitivity to TS and that TS reacts selectively with PRX3 relative to other PRX isoforms. Using recombinant PRXs 1–5, we demonstrate that TS preferentially reacts with a reduced thiolate in the PRX3 dimer at mitochondrial pH. We also show that partially oxidized PRX3 fully dissociates to dimers, while partially oxidized PRX1 and PRX2 remain largely decameric. The ability of TS to react with engineered dimers of PRX1 and PRX2 at mitochondrial pH, but inefficiently with wild-type decameric protein at cytoplasmic pH, supports a novel mechanism of action and explains the specificity of TS for PRX3. Thus, the unique structure and propensity of PRX3 to form dimers contribute to its increased sensitivity to TS-mediated inactivation, making PRX3 a promising target for prooxidant cancer therapy.

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Production and scavenging of reactive oxygen species both affect reproductive success in male and female Drosophila melanogaster

Biogerontology ◽

10.1007/s10522-021-09922-1 ◽

2021 ◽

Author(s):

Biz R. Turnell ◽

Luisa Kumpitsch ◽

Klaus Reinhardt

Keyword(s):

Reactive Oxygen Species ◽

Drosophila Melanogaster ◽

Reactive Oxygen ◽

Cellular Aging ◽

Ros Production ◽

Oxygen Species ◽

Wild Type ◽

Ros Scavenging ◽

Respiratory Pathway ◽

Male And Female

AbstractSperm aging is accelerated by the buildup of reactive oxygen species (ROS), which cause oxidative damage to various cellular components. Aging can be slowed by limiting the production of mitochondrial ROS and by increasing the production of antioxidants, both of which can be generated in the sperm cell itself or in the surrounding somatic tissues of the male and female reproductive tracts. However, few studies have compared the separate contributions of ROS production and ROS scavenging to sperm aging, or to cellular aging in general. We measured reproductive fitness in two lines of Drosophila melanogaster genetically engineered to (1) produce fewer ROS via expression of alternative oxidase (AOX), an alternative respiratory pathway; or (2) scavenge fewer ROS due to a loss-of-function mutation in the antioxidant gene dj-1β. Wild-type females mated to AOX males had increased fecundity and longer fertility durations, consistent with slower aging in AOX sperm. Contrary to expectations, fitness was not reduced in wild-type females mated to dj-1β males. Fecundity and fertility duration were increased in AOX and decreased in dj-1β females, indicating that female ROS levels may affect aging rates in stored sperm and/or eggs. Finally, we found evidence that accelerated aging in dj-1β sperm may have selected for more frequent mating. Our results help to clarify the relative roles of ROS production and ROS scavenging in the male and female reproductive systems.

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Somatic production of reactive oxygen species does not predict its production in sperm cells across Drosophila melanogaster lines

BMC Research Notes ◽

10.1186/s13104-021-05550-7 ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Biz R. Turnell ◽

Luisa Kumpitsch ◽

Anne-Cécile Ribou ◽

Klaus Reinhardt

Keyword(s):

Reactive Oxygen Species ◽

Drosophila Melanogaster ◽

Reactive Oxygen ◽

Future Research ◽

Ros Production ◽

Oxygen Species ◽

Loss Of Function ◽

Wild Type ◽

Ros Scavenging ◽

Transport Chain

Abstract Objective Sperm ageing has major evolutionary implications but has received comparatively little attention. Ageing in sperm and other cells is driven largely by oxidative damage from reactive oxygen species (ROS) generated by the mitochondria. Rates of organismal ageing differ across species and are theorized to be linked to somatic ROS levels. However, it is unknown whether sperm ageing rates are correlated with organismal ageing rates. Here, we investigate this question by comparing sperm ROS production in four lines of Drosophila melanogaster that have previously been shown to differ in somatic mitochondrial ROS production, including two commonly used wild-type lines and two lines with genetic modifications standardly used in ageing research. Results Somatic ROS production was previously shown to be lower in wild-type Oregon-R than in wild-type Dahomey flies; decreased by the expression of alternative oxidase (AOX), a protein that shortens the electron transport chain; and increased by a loss-of-function mutation in dj-1β, a gene involved in ROS scavenging. Contrary to predictions, we found no differences among these four lines in the rate of sperm ROS production. We discuss the implications of our results, the limitations of our study, and possible directions for future research.

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Evaluation of wild-type MIC distributions as a tool for determination of clinical breakpoints for Mycobacterium tuberculosis

Journal of Antimicrobial Chemotherapy ◽

10.1093/jac/dkp262 ◽

2009 ◽

Vol 64 (4) ◽

pp. 786-793 ◽

Cited By ~ 64

Author(s):

T. Schon ◽

P. Jureen ◽

C. G. Giske ◽

E. Chryssanthou ◽

E. Sturegard ◽

...

Keyword(s):

Mycobacterium Tuberculosis ◽

Wild Type ◽

Clinical Breakpoints

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Expression Level of Mature miR172 in Wild Type and StSUT4-Silenced Plants of Solanum tuberosum Is Sucrose-Dependent

International Journal of Molecular Sciences ◽

10.3390/ijms22031455 ◽

2021 ◽

Vol 22 (3) ◽

pp. 1455

Author(s):

Varsha Garg ◽

Aleksandra Hackel ◽

Christina Kühn

Keyword(s):

Solanum Tuberosum ◽

Wild Type ◽

Potato Plants ◽

Mature Leaves ◽

In Vitro Plantlets ◽

Long Time ◽

Short Time ◽

Cut Leaves

In potato plants, the phloem-mobile miR172 is involved in the sugar-dependent transmission of flower and tuber inducing signal transduction pathways and a clear link between solute transport and the induction of flowering and tuberization was demonstrated. The sucrose transporter StSUT4 seems to play an important role in the photoperiod-dependent triggering of both developmental processes, flowering and tuberization, and the phenotype of StSUT4-inhibited potato plants is reminiscent to miR172 overexpressing plants. The first aim of this study was the determination of the level of miR172 in sink and source leaves of StSUT4-silenced as well as StSUT4-overexpressing plants in comparison to Solanum tuberosum ssp. Andigena wild type plants. The second aim was to investigate the effect of sugars on the level of miRNA172 in whole cut leaves, as well as in whole in vitro plantlets that were supplemented with exogenous sugars. Experiments clearly show a sucrose-dependent induction of the level of mature miR172 in short time as well as long time experiments. A sucrose-dependent accumulation of miR172 was also measured in mature leaves of StSUT4-silenced plants where sucrose export is delayed and sucrose accumulates at the end of the light period.

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