scholarly journals Two Mutants Affecting Adaptative Responses to Abiotic Stresses in Barley Seedlings

2011 ◽  
Vol 41 (No. 1) ◽  
pp. 1-10 ◽  
Author(s):  
A.E. Martínez ◽  
A. Landau ◽  
P.T. García ◽  
G. Polenta ◽  
M.C. Arias ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Photosystem I ◽  
Abiotic Stresses ◽  
Higher Plants ◽  
Nuclear Gene ◽  
The Other ◽  
Wild Type ◽  
Seedling Roots ◽  
In The Wild ◽  
Photosystem I And Ii

Two novel mutants which affect the adaptative responses of barley seedlings to different abiotic stresses are described. They allow us to explore some aspects of adaptative phenomena that are little known in higher plants. One of these mutants corresponds to a nuclear gene which under certain circumstances in the wild type barley induces additional ethylene production in the seedling roots. This mechanism seems to be involved in inducing a negative hydrotropic growth of the roots, a phenomenon that we interpret as a response avoiding waterlogging. The other mutant corresponds to a plastid encoded gene which is involved in photosystem I and II stability and, probably, indirectly affects the acclimation of the seedlings to higher temperatures, a fact which seems to occur through the control of unsaturation/saturation levels of the thylakoid membrane fatty acids.  

scholarly journals Ester-Producing Mechanism of Ethanol O-acyltransferaseEHT1Gene inPichia pastorisfrom Shanxi Aged Vinegar

2019 ◽  
Vol 2019 ◽  
pp. 1-9
Author(s):  
Jia Chen ◽  
Ruipeng Nan ◽  
Rufu Wang ◽  
Lixin Zhang ◽  
Junfeng Shi
Keyword(s):  
Fatty Acids ◽  
Esterase Activity ◽  
Volatile Fatty Acids ◽  
The Other ◽  
Fatty Acid Esters ◽  
Wild Type ◽  
Fermentation Products ◽  
Over Expression ◽  
In The Wild ◽  
Methyl Nonanoate

The ethanol O-acyltransferaseEHT1is an important element of key signaling pathways and is widely expressed in yeast strains. In this study, we investigated the expression ofEHT1 in the overexpression lines or knockout system ofPichia pastorisusing qRT-PCR and western blotting. The amount of total protein was determined using the Bradford method; the esterase activity was determined using p-nitrophenyl acetate as a substrate, and the production of volatile fatty acids in wild-type, knockout, and over-expression systems was detected using SPME GC-MS. The esterase activity ofEHT1-knockoutP. pastoriswas significantly lower than that in wild type (P<0.01), and the activities of esterase in threeEHT1-overexpressing strains—OE-1, OE-2, and OE-3—were significantly higher than those in wild type (P<0.01). In theEHT1-knockout strain products, the contents of nine volatile fatty acids were significantly lower than those in wild type (P<0.01), and the relative percentages of three fatty acids, methyl nonanoate, methyl decanoate, and ethyl caprate, were significantly lower than those in the other six species in the wild-type and knockout groups (P<0.05). The nine volatile fatty acids in the fermentation products of the overexpressedEHT1 gene were significantly higher than those in the wild-type group (P<0.01). The relative percentages of the three fatty acid esters, methyl nonanoate, methyl caprate, and ethyl caprate, were significantly higher than those in the other six species (P<0.05).EHT1 plays an important regulatory role in esterase activity and the production of medium-chain volatile fatty acids.

arc6, an extreme chloroplast division mutant of Arabidopsis also alters proplastid proliferation and morphology in shoot and root apices

1995 ◽  
Vol 108 (9) ◽  
pp. 2937-2944 ◽  
Author(s):  
E.J. Robertson ◽  
K.A. Pyke ◽  
R.M. Leech
Keyword(s):  
Higher Plants ◽  
Nuclear Gene ◽  
Mesophyll Cell ◽  
Wild Type ◽  
Plastid Development ◽  
Plastid Differentiation ◽  
Root Cells ◽  
In The Wild ◽  
Variable Morphology ◽  
Root Apices

The arc6 (accumulation and replication of chloroplasts) mutant of Arabidopsis has only two greatly enlarged chloroplasts per mature leaf mesophyll cell compared with ninety chloroplasts per cell in the wild type. The mutation is a single nuclear gene and the plant phenotype is normal. Shoot and root apical meristems of arc6 plants have been examined to determine how early during plastid development the mutant arc6 phenotype can be recognised. In the cells of the arc6 apical meristem there are only two proplastids, which are larger than wild type with a highly variable morphology. In the cells of the leaf primordia where differentiation of proplastids to chloroplasts occurs arc6 plastids are larger and at a more advanced developmental stage than wild-type plastids. In arc6 root cells statoliths and other plastids also show grossly abnormal morphology and the statoliths are greatly increased in size. During arc6 stomatal guard cell development the perturbation in proplastid population dynamics affects plastid segregation and 30% of stomata lack plastids in one or both guard cells. Our evidence would suggest that ARC6 is expressed throughout the vegetative cells of the Arabidopsis seedling with major effects on both the proplastid phenotype and the proplastid population. ARC6 is the first gene to be identified in Arabidopsis which has a global effect on plastid development in cells arising from both the shoot and root meristems, and is of major importance in the nuclear control of plastid differentiation in higher plants.

scholarly journals Cytokinesis in fra2 Arabidopsis thaliana p60-katanin Mutant: Defects in Cell Plate/Daughter Wall Formation

2021 ◽  
Author(s):  
Emmanuel Panteris ◽  
Anna Kouskouveli ◽  
Dimitris Pappas ◽  
Ioannis-Dimosthenis S. Adamakis
Keyword(s):  
Arabidopsis Thaliana ◽  
Cell Wall ◽  
Cell Walls ◽  
Higher Plants ◽  
Cell Plate ◽  
Wild Type ◽  
Microtubule Organization ◽  
Root Cells ◽  
Wall Formation ◽  
In The Wild

Cytokinesis is accomplished in higher plants by the phragmoplast, creating and conducting the cell plate, to separate daughter nuclei by a new cell wall. The microtubule-severing enzyme p60-katanin plays an important role in the centrifugal expansion and timely disappearance of phragmoplast microtubules. Consequently, aberrant structure and delayed expansion rate of the phragmoplast occur in p60-katanin mutants. Here, the consequences of p60-katanin malfunction in cell plate/daughter wall formation were investigated by transmission electron microscopy (TEM), while deviations in the chemical composition of cell plate/new cell wall were identified by immunolabeling and confocal microscopy, in root cells of the fra2 Arabidopsis thaliana mutant. It was found that, apart from defective phragmoplast microtubule organization, cell plates/new cell walls appeared also faulty in structure, being unevenly thick and perforated by large gaps. In addition, demethylesterified homogalacturonans were prematurely present in fra2 cell plates, while callose content was significantly lower than in the wild-type. Furthermore, KNOLLE syntaxin disappeared from newly formed cell walls in fra2 earlier than in the wild-type. Taken together, these observations indicate that delayed cytokinesis, due to faulty phragmoplast organization and expansion, results in a loss of synchronization between cell plate growth and its chemical maturation.

scholarly journals Pleiotropic Effects of Inactivating a Carboxyl-Terminal Protease, CtpA, in Borrelia burgdorferi

2004 ◽  
Vol 186 (7) ◽  
pp. 2074-2084 ◽  
Author(s):  
Yngve Östberg ◽  
James A. Carroll ◽  
Marija Pinne ◽  
Jonathan G. Krum ◽  
Patricia Rosa ◽  
...  
Keyword(s):  
Borrelia Burgdorferi ◽  
Higher Plants ◽  
Bacterial Species ◽  
Immunoblot Analysis ◽  
Pleiotropic Effect ◽  
Wild Type ◽  
Gene Encoding ◽  
Two Dimensional Gel Electrophoresis ◽  
In The Wild ◽  
Carboxyl Terminal

ABSTRACT A gene encoding a putative carboxyl-terminal protease (CtpA), an unusual type of protease, is present in the Borrelia burgdorferi B31 genome. The B. burgdorferi CtpA amino acid sequence exhibits similarities to the sequences of the CtpA enzymes of the cyanobacterium Synechocystis sp. strain PCC 6803 and higher plants and also exhibits similarities to the sequences of putative CtpA proteins in other bacterial species. Here, we studied the effect of ctpA gene inactivation on the B. burgdorferi protein expression profile. Total B. burgdorferi proteins were separated by two-dimensional gel electrophoresis, and the results revealed that six proteins of the wild type were not detected in the ctpA mutant and that nine proteins observed in the ctpA mutant were undetectable in the wild type. Immunoblot analysis showed that the integral outer membrane protein P13 was larger and had a more acidic pI in the ctpA mutant, which is consistent with the theoretical change in pI for P13 not processed at the carboxyl terminus. Matrix-assisted laser desorption ionization—time of flight data indicated that in addition to P13, the BB0323 protein may serve as a substrate for carboxyl-terminal processing by CtpA. Complementation analysis of the ctpA mutant provided strong evidence that the observed effect on proteins depended on inactivation of the ctpA gene alone. We show that CtpA in B. burgdorferi is involved in the processing of proteins such as P13 and BB0323 and that inactivation of ctpA has a pleiotropic effect on borrelial protein synthesis. To our knowledge, this is the first analysis of both a CtpA protease and different substrate proteins in a pathogenic bacterium.

Characterization of a Light-Induced Oxygen-Uptake in Tobacco Protoplasts

1979 ◽  
Vol 34 (7-8) ◽  
pp. 570-575 ◽  
Author(s):  
Georg H. Schmid ◽  
Pierre Thibault
Keyword(s):  
Oxygen Uptake ◽  
Oxygen Evolution ◽  
Photosystem I ◽  
Action Spectrum ◽  
Photosynthetic Oxygen Evolution ◽  
Yellow Leaf ◽  
Wild Type ◽  
In The Wild ◽  
Aurea Mutant ◽  
Yellow Pigments

Abstract Protoplasts prepared from the wild type tobacco N. tabacum var. John William’s Broadleaf exhibit photosynthetic oxygen-evolution if the suspension medium is supplemented with bicarbonate. In the absence of bicarbonate no steady state oxygen-evolution is observed with such preparations. Instead, an appreciable uptake which is mainly insensitive to DCMU and which persists over hours, and therefore is no induction phenomenon, is seen. Protoplasts of the tobacco aurea mutant Su/su, which is a plant with an exceptionally high photorespiration, show an oxygen consumption in the light which is 4 to 5 times higher per protoplast than in the wild type. Again, the uptake is practically insensitive to DCMU which means that the effect is to be associated with photosystem I. This is further substantiated by the fact that protoplasts prepared from yellow leaf1 sec­tions of the variegated tobacco mutant NC 95 also show the light induced uptake. As reported earlier, the yellow leaf sections of this mutant exhibit only photosystem I reactions.The action spectrum for this oxygen-uptake yields the spectrum of chlorophyll. Consequently, this uptake is an inherent property of the chloroplast and has nothing to do with earlier described, light-dependent oxygen consumptions, which were mainly driven by blue light and hence used some yellow pigment as the photoreceptor. No effect or contribution of yellow pigments such as carotenoids is seen since the action spectrum with the yellow tobacco mutants which have an up to 4 fold higher carotenoid/chlorophyll ratio than the wild type is identical to that of the wild type.

Developmentally related changes in the production and expression of endo-β-1,4-glucanases in Aspergillus nidulans

Genome ◽  
1989 ◽  
Vol 32 (2) ◽  
pp. 288-292 ◽  
Author(s):  
P. S. Bagga ◽  
S. Sharma ◽  
D. K. Sandhu
Keyword(s):  
Aspergillus Nidulans ◽  
The Other ◽  
Wild Type ◽  
Stages Of Development ◽  
Experimental Conditions ◽  
The Third ◽  
Developmental Mutants ◽  
Mutant Strains ◽  
In The Wild ◽  
Low Levels

The production and electrophoretic expression of endoglucanase(s) were compared in the wild-type and three developmental mutants of Aspergillus nidulans. In the wild type, the production of endoglucanase and its distribution in extracellular and intracellular fractions varied with the age of the culture and the yield was better in stable cultures (production of conidia and cleistothecia) as compared with shake cultures (vegetative hyphae only). Two developmental mutants, aco-T69 and aco-40, which lack the development of conidia and cleistothecia, produced low levels of endoglucanase enzymes as compared with the wild type grown under similar conditions. On the other hand, in aco-90, a mutant capable of producing cleistothecia but no conidia, endoglucanase production was better. The results indicate a correlation between cleistothecial development and endoglucanase level. The electrophoretic studies revealed the presence of three forms of endoglucanase, i.e., EGI, EGII, and EGIII. The first two were detectable in the wild type as well as in mutant strains when grown under various experimental conditions and at all the stages of development. However, the third form could be observed only during cleistothecial development, indicating that this isozyme is developmentally regulated.Key words: endoglucanases, development, Aspergillus nidulans.

scholarly journals Engineering the substrate specificity of Bacillus megaterium cytochrome P-450 BM3: hydroxylation of alkyl trimethylammonium compounds

1997 ◽  
Vol 327 (2) ◽  
pp. 537-544 ◽  
Author(s):  
F. Catherine OLIVER ◽  
Sandeep MODI ◽  
U. William PRIMROSE ◽  
Lu-Yun LIAN ◽  
C. K. Gordon ROBERTS
Keyword(s):  
Fatty Acids ◽  
Bacillus Megaterium ◽  
Three Dimensional ◽  
Pair Interaction ◽  
Dimensional Structure ◽  
Wild Type ◽  
Wild Type Enzyme ◽  
Steady State Kinetics ◽  
In The Wild ◽  
Cytochrome P 450

Oligonucleotide-directed mutagenesis has been used to replace arginine-47 with glutamate in cytochrome P-450 BM3 from Bacillus megaterium and in its haem domain. The mutant has been characterized by sequencing, mass spectrometry, steady-state kinetics and by optical and NMR measurements of substrate binding. The mutant retains significant catalytic activity towards C12-C16 fatty acids, catalysing hydroxylation in the same (ω-1, ω-2, ω-3) positions with kcat/Km values a factor of 14-21 lower. C12-C16 alkyl trimethylammonium compounds are relatively poor substrates for the wild-type enzyme, but are efficiently hydroxylated by the arginine-47 → glutamate mutant at the ω-1, ω-2 and ω-3 positions, with kcat values of up to 19 s-1. Optical spectroscopy shows that the binding of the C14 and C16 alkyl trimethylammonium compounds to the mutant is similar to that of the corresponding fatty acids to the wild-type enzyme. Paramagnetic relaxation measurements show that laurate binds to the ferric state of the mutant in a significantly different position, 1.5 Å closer to the iron, than seen in the wild-type, although this difference is much smaller (~ 0.2 Å) in the ferrous state of the complex. The binding of a substrate having the same charge as residue 47 to the ferric state of the enzyme is roughly ten times weaker than that of a substrate having the opposite charge (and thus is able to make an ion-pair interaction with this residue). The results are discussed in the light of the three-dimensional structure of the enzyme.

scholarly journals Role of Unsaturated Fatty Acid Biosynthesis in Virulence of Streptococcus mutans

2007 ◽  
Vol 75 (3) ◽  
pp. 1537-1539 ◽  
Author(s):  
Elizabeth M. Fozo ◽  
Kathy Scott-Anne ◽  
Hyun Koo ◽  
Robert G. Quivey
Keyword(s):  
Fatty Acids ◽  
Streptococcus Mutans ◽  
Type Strain ◽  
Wild Type Strain ◽  
Fatty Acid Biosynthesis ◽  
Wild Type ◽  
Acid Biosynthesis ◽  
Carious Lesions ◽  
In The Wild

ABSTRACT An insertionally inactivated fabM strain of Streptococcus mutans does not produce unsaturated membrane fatty acids and is acid sensitive (E. M. Fozo and R. G. Quivey, Jr., J. Bacteriol. 186:4152-4158, 2004). In this study, the strain was shown to be poorly transmissible from host to host. Animals directly infected with the fabM strain exhibited fewer and less severe carious lesions than those observed in the wild-type strain.

scholarly journals Cytokinesis in fra2 Arabidopsis thaliana p60-Katanin Mutant: Defects in Cell Plate/Daughter Wall Formation

2021 ◽  
Vol 22 (3) ◽  
pp. 1405
Author(s):  
Emmanuel Panteris ◽  
Anna Kouskouveli ◽  
Dimitris Pappas ◽  
Ioannis-Dimosthenis S. Adamakis
Keyword(s):  
Arabidopsis Thaliana ◽  
Cell Wall ◽  
Cell Walls ◽  
Higher Plants ◽  
Cell Plate ◽  
Wild Type ◽  
Microtubule Organization ◽  
Root Cells ◽  
Wall Formation ◽  
In The Wild

Cytokinesis is accomplished in higher plants by the phragmoplast, creating and conducting the cell plate to separate daughter nuclei by a new cell wall. The microtubule-severing enzyme p60-katanin plays an important role in the centrifugal expansion and timely disappearance of phragmoplast microtubules. Consequently, aberrant structure and delayed expansion rate of the phragmoplast have been reported to occur in p60-katanin mutants. Here, the consequences of p60-katanin malfunction in cell plate/daughter wall formation were investigated by transmission electron microscopy (TEM), in root cells of the fra2 Arabidopsis thaliana loss-of-function mutant. In addition, deviations in the chemical composition of cell plate/new cell wall were identified by immunolabeling and confocal microscopy. It was found that, apart from defective phragmoplast microtubule organization, cell plates/new cell walls also appeared faulty in structure, being unevenly thick and perforated by large gaps. In addition, demethylesterified homogalacturonans were prematurely present in fra2 cell plates, while callose content was significantly lower than in the wild type. Furthermore, KNOLLE syntaxin disappeared from newly formed cell walls in fra2 earlier than in the wild type. Taken together, these observations indicate that delayed cytokinesis, due to faulty phragmoplast organization and expansion, results in a loss of synchronization between cell plate growth and its chemical maturation.

scholarly journals Multiple Translational Control Sequences in the 5′ Leader of the Chloroplast psbC mRNA Interact With Nuclear Gene Products in Chlamydomonas reinhardtii

Genetics ◽  
2003 ◽  
Vol 163 (3) ◽  
pp. 895-904
Author(s):  
William Zerges ◽  
Andrea H Auchincloss ◽  
Jean-David Rochaix
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Reporter Gene ◽  
Translational Control ◽  
Nuclear Gene ◽  
Gene Products ◽  
Wild Type ◽  
Translation Initiation Region ◽  
Mrna Stabilization ◽  
In The Wild ◽  
Nuclear Loci

Abstract Translation of the chloroplast psbC mRNA in the unicellular eukaryotic alga Chlamydomonas reinhardtii is controlled by interactions between its 547-base 5′ untranslated region and the products of the nuclear loci TBC1, TBC2, and possibly TBC3. In this study, a series of site-directed mutations in this region was generated and the ability of these constructs to drive expression of a reporter gene was assayed in chloroplast transformants that are wild type or mutant at these nuclear loci. Two regions located in the middle of the 5′ leader and near the initiation codon are important for translation. Other deletions still allow for partial expression of the reporter gene in the wild-type background. Regions with target sites for TBC1 and TBC2 were identified by estimating the residual translation activity in the respective mutant backgrounds. TBC1 targets include mostly the central part of the leader and the translation initiation region whereas the only detected TBC2 targets are in the 3′ part. The 5′-most 93 nt of the leader are required for wild-type levels of transcription and/or mRNA stabilization. The results indicate that TBC1 and TBC2 function independently and further support the possibility that TBC1 acts together with TBC3.

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