Metribuzin-Resistant Mutants of Chlamydomonas reinhardii

1984 ◽  
Vol 39 (5) ◽  
pp. 437-439 ◽  
Author(s):  
N. Pucheu ◽  
W. Oettmeier ◽  
U. Heisterkamp ◽  
K. Masson ◽  
G.F. Wildner
Keyword(s):  
Electron Transport ◽  
Photosynthetic Electron Transport ◽  
Wild Type ◽  
Binding Studies ◽  
Molecular Weight Range ◽  
Chlamydomonas Reinhardii ◽  
Thylakoid Membrane Proteins ◽  
Mutant Strains ◽  
Resistant Mutants

Herbicide resistance in Chlamydomonas reinhardii cells was induced by mutagenesis with 5-fluorodeoxyuridine and ethylmethanesulfonate. Four mutant strains were isolated and analyzed for resistance against DCMU-type or phenolic inhibitors of photosynthetic electron transport. The mutants were different in both the extent and the pattern of their resistance: the R/S value, i.e. the ratio of I50 values of the inhibition of photosynthetic electron transport in isolated resistant and susceptible thylakoids, varied for metribuzin from 10 000 to 36. The mutant MZ-1 was resistant against metribuzin, atrazine and DCMU, whereas the mutant MZ-2 showed resistance mainly against metribuzin and atrazine. The mutant MZ-3 was similar to MZ-1, but showed a lesser extent of resistance against DCMU. The mutant MZ-4 showed resistance against metribuzin, but not against atrazine. These results demonstrate that the resistance against one herbicide of the DCMU-type (metribuzin) must not be accompanied by similar resistance against te other inhibitors. Binding studies with radioactively labeled herbicides, [14C]metribuzin, [14C]atrazine and [3H]DCMU, and isolated thylakoids supported these observations. Phosphorylation of thylakoid membrane proteins was studied with wild-type cells and resistant mutants under in vivo conditions in the light. The 32P-labeled main proteins bands were in the molecular weight range of 10-14 kDa, 26-29 kDa, 32-35 kDa and 46-48 kDa. The pattern and the extent of incorporation of 32P were similar for the mutants and the wild-type cells.

Inhibition of Photosynthetic Electron Transport by the Quinone Antagonist UHDBT

1981 ◽  
Vol 36 (3-4) ◽  
pp. 272-275 ◽  
Author(s):  
Walter Oettmeier ◽  
Klaus Masson ◽  
Doris Godde
Keyword(s):  
Electron Transport ◽  
Green Alga ◽  
Photosynthetic Electron Transport ◽  
Binding Studies ◽  
Chlamydomonas Reinhardii ◽  
Efficient Inhibitor ◽  
Low Concentrations

UHDBT (5-n-undecyl-6-hydroxy-4,7-dioxobenzothiazole) is an efficient inhibitor of photosynthetic electron transport in chloroplasts from spinach (pI50-value = 7.61) and the green alga Chlamydomonas reinhardii. At low concentrations of UHDBT its site of inhibition is located at the reducing side of plastoquinone, identical to that of 3-(3,4-dichlorophenyl)-1, 1-dimethylurea (DCMU). This became evident from functional as well as binding studies. At higher concentrations of UHDBT a secondary inhibition site at the oxidizing side of plastoquinone, identical to that of 2,5-dibromo-3-methyl-6-isopropyl-1,4-benzoquinone (DBMIB) becomes evident

scholarly journals In Vivo Role of Catalase-Peroxidase inSynechocystis sp. Strain PCC 6803

1999 ◽  
Vol 181 (6) ◽  
pp. 1875-1882 ◽  
Author(s):  
Martin Tichy ◽  
Wim Vermaas
Keyword(s):  
Electron Transport ◽  
Photosynthetic Electron Transport ◽  
Protective Role ◽  
Scavenging Activity ◽  
Wild Type ◽  
Gene Coding ◽  
In The Wild ◽  
Catalase Peroxidase ◽  
Pcc 6803

ABSTRACT The katG gene coding for the only catalase-peroxidase in the cyanobacterium Synechocystis sp. strain PCC 6803 was deleted in this organism. Although the rate of H2O2 decomposition was about 30 times lower in the ΔkatG mutant than in the wild type, the strain had a normal phenotype and its doubling time as well as its resistance to H2O2 and methyl viologen were indistinguishable from those of the wild type. The residual H2O2-scavenging capacity was more than sufficient to deal with the rate of H2O2production by the cell, estimated to be less than 1% of the maximum rate of photosynthetic electron transport in vivo. We propose that catalase-peroxidase has a protective role against environmental H2O2 generated by algae or bacteria in the ecosystem (for example, in mats). This protective role is most apparent at a high cell density of the cyanobacterium. The residual H2O2-scavenging activity in the ΔkatG mutant was a light-dependent peroxidase activity. However, neither glutathione peroxidase nor ascorbate peroxidase accounted for a significant part of this H2O2-scavenging activity. When a small thiol such as dithiothreitol was added to the medium, the rate of H2O2 decomposition in the ΔkatG mutant increased more than 10-fold, indicating that a thiol-specific peroxidase, for which thioredoxin may be the physiological electron donor, is present. Oxidized thioredoxin is likely to be reduced again by photosynthetic electron transport. Therefore, under laboratory conditions, there are only two enzymatic mechanisms for H2O2 decomposition present inSynechocystis sp. strain PCC 6803. One is catalyzed by a catalase-peroxidase, and the other is catalyzed by thiol-specific peroxidase.

scholarly journals N-3-Hydroxy Dodecanoyl-DL-homoserine Lactone (OH-dDHL) Triggers Apoptosis of Bone Marrow-Derived Macrophages through the ER- and Mitochondria-Mediated Pathways

2021 ◽  
Vol 22 (14) ◽  
pp. 7565
Author(s):  
Kyungho Woo ◽  
Dong Ho Kim ◽  
Man Hwan Oh ◽  
Ho Sung Park ◽  
Chul Hee Choi
Keyword(s):  
Bone Marrow ◽  
Quorum Sensing ◽  
Deletion Mutant ◽  
Transmembrane Protein ◽  
Cell Communication ◽  
Homoserine Lactone ◽  
Host Responses ◽  
Wild Type ◽  
Mutant Strains

Quorum sensing of Acinetobacter nosocomialis for cell-to-cell communication produces N-3-hydroxy dodecanoyl-DL-homoserine lactone (OH-dDHL) by an AnoR/I two-component system. However, OH-dDHL-driven apoptotic mechanisms in hosts have not been clearly defined. Here, we investigated the induction of apoptosis signaling pathways in bone marrow-derived macrophages treated with synthetic OH-dDHL. Moreover, the quorum-sensing system for virulence regulation was evaluated in vivo using wild-type and anoI-deletion mutant strains. OH-dDHL decreased the viability of macrophage and epithelial cells in dose- and time-dependent manners. OH-dDHL induced Ca2+ efflux and caspase-12 activation by ER stress transmembrane protein (IRE1 and ATF6a p50) aggregation and induced mitochondrial dysfunction through reactive oxygen species (ROS) production, which caused cytochrome c to leak. Pretreatment with a pan-caspase inhibitor reduced caspase-3, -8, and -9, which were activated by OH-dDHL. Pro-inflammatory cytokine and paraoxonase-2 (PON2) gene expression were increased by OH-dDHL. We showed that the anoI-deletion mutant strains have less intracellular invasion compared to the wild-type strain, and their virulence, such as colonization and dissemination, was decreased in vivo. Consequently, these findings revealed that OH-dDHL, as a virulence factor, contributes to bacterial infection and survival as well as the modification of host responses in the early stages of infection.

scholarly journals TIP family aquaporins play role in chloroplast osmoregulation and photosynthesis

2020 ◽  
Author(s):  
Azeez Beebo ◽  
Ahmad Zia ◽  
Christopher R. Kinzel ◽  
Andrei Herdean ◽  
Karim Bouhidel ◽  
...  
Keyword(s):  
Electron Transport ◽  
Oxygen Evolution ◽  
Photosynthetic Electron Transport ◽  
Chloroplast Envelope ◽  
Photosynthetic Oxygen Evolution ◽  
Wild Type ◽  
Thylakoid Lumen ◽  
Photosynthetic Oxygen ◽  
Osmotic Treatment ◽  
Envelope Membranes

SUMMARYPhotosynthetic oxygen evolution by photosystem II requires water supply into the chloroplast to reach the thylakoid lumen. A rapid water flow is also required into the chloroplast for optimal oxygen evolution and to overcome osmotic stress. The mechanisms governing water transport in chloroplasts are largely unexplored. Previous proteomics indicated the presence of three aquaporins from the tonoplast intrinsic protein (TIP) family, TIP1;1, TIP1;2 and TIP2;1, in chloroplast membranes of Arabidopsis thaliana. Here we revisited their location and studied their role in chloroplasts. Localization experiments indicated that TIP2;1 resides in the thylakoid, whereas TIP1;2 is present in both thylakoid and envelope membranes. Mutants lacking TIP1;2 and/or TIP2;1 did not display a macroscopic phenotype when grown under standard conditions. The mutant chloroplasts and thylakoids underwent less volume changes than the corresponding wild type preparations upon osmotic treatment and in the light. Significantly reduced rates of photosynthetic electron transport were obtained in the mutant leaves, with implications on the CO2 fixation rates. However, electron transport rates did not significantly differ between mutants and wild type when isolated thylakoids were examined. Less acidification of the thylakoid lumen was measured in mutants thylakoids, resulting in a slower induction of delta pH-dependent photoprotective mechanisms. These results identify TIP1;2 and TIP2;1 as chloroplast proteins and highlight their importance for osmoregulation and optimal photosynthesis. A third aquaporin, TIP1;1, is present in the chloroplast envelope, and may play role in photosynthesis under excessive light conditions, as based on the weak photosynthetic phenotype of its mutant.

Cyanoacrylate Inhibitors of Photosynthetic Electron Transport in Atrazine Susceptible and Atrazine Resistant Brassica Chloroplasts

1987 ◽  
Vol 42 (6) ◽  
pp. 670-673 ◽  
Author(s):  
John N. Phillips ◽  
John L. Huppatz
Keyword(s):  
Electron Transport ◽  
Inhibitory Activity ◽  
Photosynthetic Electron Transport ◽  
Resistant Mutant ◽  
Herbicidal Activity ◽  
Optical Isomers ◽  
Wild Type ◽  
Specific Receptor ◽  
Receptor Sites ◽  
Alkyl Moiety

Comparison of the p/50 values for a series of cyanoacrylate derivatives in chloroplasts isolated from atrazinc susccptiblc (wild type) and atrazine resistant (mutant) Brassica napus biotvpes reveal that the degree and direction of discrimination can vary from being 200- fold more active against the wild type to 10-fold more active against the mutant. There appears to be a direct correlation between the level of inhibitory activity in thylakoids isolated from “susceptible” chloroplasts and the level of discrimination between “susceptible” and “resistant” chloroplasts - a correlation which can be improved by allowing for variations in molecular hydrophobicity. Studies with optically active ethoxyethyl-3-alkyl-2-cyano-3-α-methylbenzylamino acrylates suggest that there are specific receptor sites present in both “susceptible” and “resistant” chloroplasts for both the a-methylbenzyl chiral centre and the 3-alkyl moiety. There is a direct relationship between photosynthetic electron transport inhibitory activity and herbicidal activity of optical isomers.

Calreticulin Mediates Anesthetic Sensitivity in Drosophila melanogaster 

2003 ◽  
Vol 99 (4) ◽  
pp. 867-875 ◽  
Author(s):  
Sumiko Gamo ◽  
Junya Tomida ◽  
Katsuyuki Dodo ◽  
Dai Keyakidani ◽  
Hitoshi Matakatsu ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Double Mutant ◽  
Developmental Stages ◽  
Northern Blotting ◽  
General Anesthetics ◽  
Wild Type ◽  
Mutant Strains ◽  
Low Expression

Background Various species, e.g., Caenorhabditis elegans, Drosophila melanogaster, and mice, have been used to explore the mechanisms of action of general anesthetics in vivo. The authors isolated a Drosophila mutant, ethas311, that was hypersensitive to diethylether and characterized the calreticulin (crc) gene as a candidate of altered anesthetic sensitivity. Methods Molecular analysis of crc included cloning and sequencing of the cDNA, Northern blotting, and in situ hybridization to accomplish the function of the gene and its mutation. For anesthetic phenotype assay, the 50% anesthetizing concentrations were determined for ethas311, revertants, and double-mutant strains (wild-type crc transgene plus ethas311). Results Expression of the crc 1.4-kb transcript was lower in the mutant ethas311 than in the wild type at all developmental stages. The highest expression at 19 h after pupation was observed in the brain of the wild type but was still low in the mutant at that stage. The mutant showed resistance to isoflurane as well as hypersensitivity to diethylether, whereas it showed the wild phenotype to halothane. Both mutant phenotypes were restored to the wild type in the revertants and double-mutant strains. Conclusion ethas311 is a mutation of low expression of the Drosophila calreticulin gene. The authors demonstrated that hypersensitivity to diethylether and resistance to isoflurane are associated with low expression of the gene. In Drosophila, calreticulin seems to mediate these anesthetic sensitivities, and it is a possible target for diethylether and isoflurane, although the predicted anesthetic targets based on many studies in vitro and in vivo are the membrane proteins, such as ion channels and receptors.

scholarly journals The Entner-Doudoroff Pathway Has Little Effect on Helicobacter pylori Colonization of Mice

2003 ◽  
Vol 71 (5) ◽  
pp. 2920-2923 ◽  
Author(s):  
Amy E. Wanken ◽  
Tyrrell Conway ◽  
Kathryn A. Eaton
Keyword(s):  
Helicobacter Pylori ◽  
Wild Type ◽  
Mutant Strains ◽  
H Pylori ◽  
Type Strains

ABSTRACT Helicobacter pylori mutants deficient in 6-phosphogluconate dehydratase (6PGD) were constructed. Colonization densities were lower and minimum infectious doses were higher for mutant strains than for wild-type strains. In spite of better colonization, however, wild-type strains did not displace the mutant in cocolonization experiments. Loss of 6PGD diminishes the fitness of H. pylori in vivo, but the pathway is nonessential for colonization.

scholarly journals phgABC, a Three-Gene Operon Required for Growth of Streptococcus pneumoniae in Hyperosmotic Medium and In Vivo

2004 ◽  
Vol 72 (8) ◽  
pp. 4579-4588 ◽  
Author(s):  
Jeremy S. Brown ◽  
Sarah M. Gilliland ◽  
Shilpa Basavanna ◽  
David W. Holden
Keyword(s):  
Streptococcus Pneumoniae ◽  
Mutant Strain ◽  
Compatible Solutes ◽  
Wild Type ◽  
Gram Positive Bacteria ◽  
Mutant Strains ◽  
Increased Sensitivity ◽  
Related Proteins ◽  
And Oxidative Stress

ABSTRACT To cause disease, bacterial pathogens need to be able to adapt to the physiological conditions found within the host, including an osmolality of approximately 290 mosmol kg−1. While investigating Streptococcus pneumoniae genes contained within pneumococcal pathogenicity island 1, we identified a three-gene operon of unknown function termed phgABC. PhgC has a domain with similarity to diacylglycerol kinases of eukaryotes and is the first described member of a family of related proteins found in many gram-positive bacteria. phgA and phgC mutant strains were constructed by insertional duplication mutagenesis and found to have impaired growth under conditions of high osmotic and oxidative stress. The compatible solutes proline and glycine betaine improved growth of the wild-type and the phgA mutant strains in hyperosmolar medium, and when analyzed by electron microscopy, the cellular morphology of the phgA mutant strain was unaffected by osmotic stress. The phgA and phgC mutant strains were reduced in virulence in models of both systemic and pulmonary infection. As the virulence of the phgA mutant strain was not restored in gp91phox−/− mice and the phgA and phgC mutant strains had reduced growth in both blood and serum, the reduced virulence of these strains is unlikely to be due to increased sensitivity to the respiratory burst of phagocytes but is, instead, due to impaired growth at physiological osmolality.

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