Development of Photochemical Activity in Chloroplast Membranes. I. Studies With Mutants of Barley Grown Under a Single Environment

1977 ◽  
Vol 4 (3) ◽  
pp. 415 ◽  
Author(s):  
RM Smillie ◽  
NC Nielsen ◽  
KW Kenningsen ◽  
DV Wettstein
Keyword(s):  
Nuclear Gene ◽  
Protein Composition ◽  
Thylakoid Membranes ◽  
Photochemical Activity ◽  
Wild Type ◽  
Membrane Systems ◽  
Chloroplast Membranes ◽  
Pump Activity ◽  
Low Activity ◽  
Single Set

The development of photochemical competence in chloroplast thylakoid membranes was studied using a series of nuclear gene mutants of barley. The chloroplasts of each mutant reached a different developmental stage when grown under a single set of environmental conditions. Photochemical capacity as well as morphological and compositional features were compared for chloroplasts in the primary leaves of eight mutants and wild-type barley (Hordeum vulgare cv. Sval�fs Bonus) after growth of the plants for 7 days at 21°C and 1700 lux. The results obtained indicated a sequence for the progressive acquisition of photochemical capability by the chloroplast membranes. The least developed of the mutant chloroplasts photoreduced ferricyanide but not 2,6-dichloroindophenol (DCIP). Immature chloroplast membrane systems from other slightly more developed mutants showed a low activity for DCIP photoreduction which was stimulated by diphenylcarbazide. In these mutants, however, the rate of photoreduction of ferricyanide was not stimulated by the uncoupler methylamine, proton pump activity was not detected and photosystem I activity was low. In the more developed of the mutant thylakoid systems, photoreductive activity was stimulated by methylamine and a proton gradient was generated in the light. The more developed the system, the greater was the stimulation obtained with methylamine. Other changes which were correlated with lamellar membrane development included a decrease in the light intensity required to saturate ferricyanide and DCIP photoreductive activities and an increase in the degree of inhibition of the photoreduction of ferricyanide by the photosystem II inhibitor 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU). The activity changes were not correlated with either the amount of grana present or the ratio of chlorophyll a to b. Mutants showing low rates of DCMU-sensitive photoreduction of ferricyanide and DCIP were aberrant in protein composition of the chloroplast membranes.

Development of Photochemical Activity in Chloroplast Membranes. II. Studies With a Mutant of Barley Grown Under Different Environments

1977 ◽  
Vol 4 (3) ◽  
pp. 439 ◽  
Author(s):  
RM Smillie ◽  
NC Nielsen ◽  
KW Henningsen ◽  
DV Wettstein
Keyword(s):  
Light Intensity ◽  
Developmental Stages ◽  
Chloroplast Development ◽  
Nuclear Gene ◽  
Photochemical Activity ◽  
Hordeum Vulgare L ◽  
Chloroplast Membranes ◽  
Photochemical Activities ◽  
Gene Mutant ◽  
Isolated Chloroplasts

Chloroplast development in the barley mutant xantha-b12, a nuclear gene mutant derived from Hordeum vulgare L. cv. Sval�fs Bonus, was profoundly influenced by the temperature and light intensity to which the plants were subjected during growth. Low temperatures and high light intensities retarded chloroplast development. By growing this mutant under different combinations of temperature and light intensity, seedlings were produced containing chloroplasts at different developmental stages. Measurements of photochemical activities of the isolated chloroplasts indicated a sequence for development of photochemical competence in chloroplast membranes very similar to that adduced from a study of several different barley mutants grown under a single environment. A photoreductive capacity is initially acquired but energy conservation sites only become fully functional at an advanced stage of membrane development.

scholarly journals The TonB system in Aeromonas hydrophila NJ-35 is essential for MacA2B2 efflux pump-mediated macrolide resistance

2021 ◽  
Vol 52 (1) ◽  
Author(s):  
Yuhao Dong ◽  
Qing Li ◽  
Jinzhu Geng ◽  
Qing Cao ◽  
Dan Zhao ◽  
...  
Keyword(s):  
Aeromonas Hydrophila ◽  
Efflux Pump ◽  
Fold Increase ◽  
Activity Level ◽  
Macrolide Resistance ◽  
Wild Type ◽  
Iron Deprivation ◽  
Pump Activity ◽  
Tonb System ◽  
Increased Sensitivity

AbstractThe TonB system is generally considered as an energy transporting device for the absorption of nutrients. Our recent study showed that deletion of this system caused a significantly increased sensitivity of Aeromonas hydrophila to the macrolides erythromycin and roxithromycin, but had no effect on other classes of antibiotics. In this study, we found the sensitivity of ΔtonB123 to all macrolides tested revealed a 8- to 16-fold increase compared with the wild-type (WT) strain, but this increase was not related with iron deprivation caused by tonB123 deletion. Further study demonstrated that the deletion of tonB123 did not damage the integrity of the bacterial membrane but did hinder the function of macrolide efflux. Compared with the WT strain, deletion of macA2B2, one of two ATP-binding cassette (ABC) types of the macrolide efflux pump, enhanced the sensitivity to the same levels as those of ΔtonB123. Interestingly, the deletion of macA2B2 in the ΔtonB123 mutant did not cause further increase in sensitivity to macrolide resistance, indicating that the macrolide resistance afforded by the MacA2B2 pump was completely abrogated by tonB123 deletion. In addition, macA2B2 expression was not altered in the ΔtonB123 mutant, indicating that any influence of TonB on MacA2B2-mediated macrolide resistance was at the pump activity level. In conclusion, inactivation of the TonB system significantly compromises the resistance of A. hydrophila to macrolides, and the mechanism of action is related to the function of MacA2B2-mediated macrolide efflux.

scholarly journals Molecular Dynamics of Chloroplast Membranes Isolated from Wild-Type Barley and a Brassinosteroid-Deficient Mutant Acclimated to Low and High Temperatures

Biomolecules ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 27
Author(s):  
Iwona Sadura ◽  
Dariusz Latowski ◽  
Jana Oklestkova ◽  
Damian Gruszka ◽  
Marek Chyc ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Temperature Stress ◽  
High Temperatures ◽  
Biological Membrane ◽  
Hydrophobic Core ◽  
Wild Type ◽  
Chloroplast Membranes ◽  
Paramagnetic Resonance ◽  
Photosynthetic Membranes

Plants have developed various acclimation strategies in order to counteract the negative effects of abiotic stresses (including temperature stress), and biological membranes are important elements in these strategies. Brassinosteroids (BR) are plant steroid hormones that regulate plant growth and development and modulate their reaction against many environmental stresses including temperature stress, but their role in modifying the properties of the biological membrane is poorly known. In this paper, we characterise the molecular dynamics of chloroplast membranes that had been isolated from wild-type and a BR-deficient barley mutant that had been acclimated to low and high temperatures in order to enrich the knowledge about the role of BR as regulators of the dynamics of the photosynthetic membranes. The molecular dynamics of the membranes was investigated using electron paramagnetic resonance (EPR) spectroscopy in both a hydrophilic and hydrophobic area of the membranes. The content of BR was determined, and other important membrane components that affect their molecular dynamics such as chlorophylls, carotenoids and fatty acids in these membranes were also determined. The chloroplast membranes of the BR-mutant had a higher degree of rigidification than the membranes of the wild type. In the hydrophilic area, the most visible differences were observed in plants that had been grown at 20 °C, whereas in the hydrophobic core, they were visible at both 20 and 5 °C. There were no differences in the molecular dynamics of the studied membranes in the chloroplast membranes that had been isolated from plants that had been grown at 27 °C. The role of BR in regulating the molecular dynamics of the photosynthetic membranes will be discussed against the background of an analysis of the photosynthetic pigments and fatty acid composition in the chloroplasts.

scholarly journals Mutants inSaccharomyces lactiscontrolling both β-glucosidase and β-galactosidase activities

1972 ◽  
Vol 19 (1) ◽  
pp. 27-32 ◽  
Author(s):  
M. Tingle ◽  
H. O. Halvorson
Keyword(s):  
Nuclear Gene ◽  
Mutant Phenotype ◽  
Single Mutation ◽  
Wild Type ◽  
Genetic Studies ◽  
Glucosidase Activity ◽  
Type Strains

SUMMARYInSaccharomyces lactis, a class of mutants isolated for low β-glucosidase activity are reduced in activity for β-galactosidase as well. Genetic studies indicate that their properties are the result of a single mutation in a nuclear gene. In diploide containing a wild-type and mutant β-galactosidase allele, the mutant phenotype is partially dominant. The two enzymes can be separated physically and under appropriate conditions are induced independently in wild-type strains.

scholarly journals Alpha Carbonic Anhydrase 5 Mediates Stimulation of ATP Synthesis by Bicarbonate in Isolated Arabidopsis Thylakoids

2021 ◽  
Vol 12 ◽  
Author(s):  
Tatiana P. Fedorchuk ◽  
Inga A. Kireeva ◽  
Vera K. Opanasenko ◽  
Vasily V. Terentyev ◽  
Natalia N. Rudenko ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Arabidopsis Thaliana ◽  
Carbonic Anhydrase ◽  
Atp Synthesis ◽  
Thylakoid Membranes ◽  
Wild Type ◽  
Gene Encoding ◽  
Mutant Lines ◽  
Stimulation Of ◽  
Soluble Carbonic Anhydrase

We studied bicarbonate-induced stimulation of photophosphorylation in thylakoids isolated from leaves of Arabidopsis thaliana plants. This stimulation was not observed in thylakoids of wild-type in the presence of mafenide, a soluble carbonic anhydrase inhibitor, and was absent in thylakoids of two mutant lines lacking the gene encoding alpha carbonic anhydrase 5 (αCA5). Using mass spectrometry, we revealed the presence of αCA5 in stromal thylakoid membranes of wild-type plants. A possible mechanism of the photophosphorylation stimulation by bicarbonate that involves αCA5 is proposed.

scholarly journals STRUCTURAL DIFFERENTIATION OF STACKED AND UNSTACKED CHLOROPLAST MEMBRANES

1971 ◽  
Vol 48 (3) ◽  
pp. 594-619 ◽  
Author(s):  
Ursula W. Goodenough ◽  
L. Andrew Staehelin
Keyword(s):  
Gene Mutation ◽  
Growth Conditions ◽  
Salt Medium ◽  
Wild Type ◽  
Dense Population ◽  
Structural Differentiation ◽  
Chloroplast Membranes ◽  
Particle Distributions ◽  
Low Salt

Wild-type chloroplast membranes from Chlamydomonas reinhardi exhibit four faces in freeze-etchreplicas: the complementary Bs and Cs faces are found where the membranes are stacked together; the complementary Bu and Cu faces are found in unstacked membranes. The Bs face carries a dense population of regularly spaced particles containing the large, 160 ± 10 A particles that appear to be unique to chloroplast membranes. Under certain growth conditions, membrane stacking does not occur in the ac-5 strain. When isolated, these membranes remain unstacked, exhibit only Bu and Cu faces, and retain the ability to carry out normal photosynthesis. Membrane stacking is also absent in the ac-31 strain, and, when isolated in a low-salt medium, these membranes remain unstacked and exhibit only Bu and Cu faces. When isolated in a high-salt medium, however, they stack normally, and Bs and Cs faces are produced by this in vitro stacking process. We conclude that certain particle distributions in the chloroplast membrane are created as a consequence of the stacking process, and that the ability of membranes to stack can be modified both by gene mutation and by the ionic environment in which the membranes are found.

Murein components rescue developmental sporulation of Myxococcus xanthus

1982 ◽  
Vol 152 (1) ◽  
pp. 462-470 ◽  
Author(s):  
L J Shimkets ◽  
D Kaiser
Keyword(s):  
Fruiting Body ◽  
High Cell Density ◽  
Myxococcus Xanthus ◽  
Sodium Dodecyl ◽  
Protein Composition ◽  
Diaminopimelic Acid ◽  
Nutrient Level ◽  
High Cell ◽  
Wild Type ◽  
Nutrient Rich Medium

Murein (peptidoglycan) components are able to rescue sporulation in certain sporulation-defective mutants of Myxococcus xanthus. N-Acetylglucosamine, N-acetylmuramic acid, diaminopimelic acid, and D-alanine each increase the number of spores produced by SpoC mutants. When all four components are included they have a synergistic effect, raising the number of spores produced by SpoC mutants to the wild-type level. Murein-rescued spores are resistant to heat and sonic oscillation and germinate when plated on a nutrient-rich medium. They appear to be identical to fruiting body spores in their ultrastructure, in their protein composition, and in their resistance to boiling sodium dodecyl sulfate. Murein rescue of sporulation, like fruiting body sporulation, requires high cell density, a low nutrient level, and a solid surface.

Rpm2, the Protein Subunit of Mitochondrial RNase P in Saccharomyces cerevisiae, Also Has a Role in the Translation of Mitochondrially Encoded Subunits of Cytochrome c Oxidase

Genetics ◽  
2001 ◽  
Vol 158 (2) ◽  
pp. 573-585
Author(s):  
Vilius Stribinskis ◽  
Guo-Jian Gao ◽  
Steven R Ellis ◽  
Nancy C Martin
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Mitochondrial Biogenesis ◽  
Mitochondrial Protein ◽  
Nuclear Gene ◽  
Rnase P ◽  
Wild Type ◽  
Protein Subunit ◽  
Mitochondrial Translation

Abstract RPM2 is a Saccharomyces cerevisiae nuclear gene that encodes the protein subunit of mitochondrial RNase P and has an unknown function essential for fermentative growth. Cells lacking mitochondrial RNase P cannot respire and accumulate lesions in their mitochondrial DNA. The effects of a new RPM2 allele, rpm2-100, reveal a novel function of RPM2 in mitochondrial biogenesis. Cells with rpm2-100 as their only source of Rpm2p have correctly processed mitochondrial tRNAs but are still respiratory deficient. Mitochondrial mRNA and rRNA levels are reduced in rpm2-100 cells compared to wild type. The general reduction in mRNA is not reflected in a similar reduction in mitochondrial protein synthesis. Incorporation of labeled precursors into mitochondrially encoded Atp6, Atp8, Atp9, and Cytb protein was enhanced in the mutant relative to wild type, while incorporation into Cox1p, Cox2p, Cox3p, and Var1p was reduced. Pulse-chase analysis of mitochondrial translation revealed decreased rates of translation of COX1, COX2, and COX3 mRNAs. This decrease leads to low steady-state levels of Cox1p, Cox2p, and Cox3p, loss of visible spectra of aa3 cytochromes, and low cytochrome c oxidase activity in mutant mitochondria. Thus, RPM2 has a previously unrecognized role in mitochondrial biogenesis, in addition to its role as a subunit of mitochondrial RNase P. Moreover, there is a synthetic lethal interaction between the disruption of this novel respiratory function and the loss of wild-type mtDNA. This synthetic interaction explains why a complete deletion of RPM2 is lethal.

scholarly journals Nuclear Activation Function 2 Estrogen Receptor α Attenuates Arterial and Renal Alterations Due to Aging and Hypertension in Female Mice

2020 ◽  
Vol 9 (5) ◽  
Author(s):  
Emmanuel Guivarc'h ◽  
Julie Favre ◽  
Anne‐Laure Guihot ◽  
Emilie Vessières ◽  
Linda Grimaud ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Estrogen Receptor ◽  
Angiotensin Ii ◽  
Systolic Blood Pressure ◽  
Vascular Reactivity ◽  
Nuclear Gene ◽  
Estrogen Receptor Α ◽  
Protective Effects ◽  
Wild Type ◽  
Female Mice

Background The cardiovascular protective effects of estrogens in premenopausal women depend mainly on estrogen receptor α (ERα). ERα activates nuclear gene transcription regulation and membrane‐initiated signaling. The latter plays a key role in estrogen‐dependent activation of endothelial NO synthase. The goal of the present work was to determine the respective roles of the 2 ERα activities in endothelial function and cardiac and kidney damage in young and old female mice with hypertension, which is a major risk factor in postmenopausal women. Methods and Results Five‐ and 18‐month‐old female mice lacking either ERα (ERα −/− ), the nuclear activating function AF2 of ERα (AF2°), or membrane‐located ERα (C451A) were treated with angiotensin II (0.5 mg/kg per day) for 1 month. Systolic blood pressure, left ventricle weight, vascular reactivity, and kidney function were then assessed. Angiotensin II increased systolic blood pressure, ventricle weight, and vascular contractility in ERα −/− and AF2° mice more than in wild‐type and C451A mice, independent of age. In both the aorta and mesenteric resistance arteries, angiotensin II and aging reduced endothelium‐dependent relaxation in all groups, but this effect was more pronounced in ERα −/− and AF2° than in the wild‐type and C451A mice. Kidney inflammation and oxidative stress, as well as blood urea and creatinine levels, were also more pronounced in old hypertensive ERα −/− and AF2° than in old hypertensive wild‐type and C451A mice. Conclusions The nuclear ERα‐AF2 dependent function attenuates angiotensin II–dependent hypertension and protects target organs in aging mice, whereas membrane ERα signaling does not seem to play a role.

The structure and function of grana-free thylakoid membranes in gerontoplasts of senescent leaves of vicia faba l.

1988 ◽  
Vol 43 (1-2) ◽  
pp. 149-154 ◽  
Author(s):  
H. Oskar Schmidt
Keyword(s):  
Vicia Faba ◽  
Thylakoid Membranes ◽  
Photochemical Activity ◽  
Structure And Function ◽  
Polypeptide Composition ◽  
Light Harvesting Complex ◽  
Vicia Faba L ◽  
Light Protection ◽  
Flotation Method ◽  
And Function

In the course of yellowing (senescence) the leaves of Vicia faba L. lose 95% of their chlorophyll. Gerontoplasts develop from chloroplasts and aggregate with the pycnotic mitochondria and the cell nucleus in the senescent cells (organelle aggregation). The gerontoplasts contain only a few, unstacked thylakoid membranes but a large number of carotinoid-containing plastoglobuli, which after the degration of chlorophyll presumably assume the light protection of the cells. The thylakoid membranes of the gerontoplasts were isolated by means of a flotation method. Their polypeptide composition is characterized by a high proportion of light-harvesting complex. Evidence of relatively high photochemical activity shows that functional thylakoid membranes are present in the premortal senescence state of leaves and this suggests that there is functional compartmentation of the hydrolytic processes in this stage of the leaves’ development

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