The functional status of paraveinal mesophyll vacuoles changes in response to altered metabolic conditions in soybean leaves

2005 ◽  
Vol 32 (4) ◽  
pp. 335 ◽  
Author(s):  
Kimberly A. Murphy ◽  
Rachel A. Kuhle ◽  
Andreas M. Fischer ◽  
Aldwin M. Anterola ◽  
Howard D. Grimes
Keyword(s):  
Functional Status ◽  
Storage Proteins ◽  
Vegetative Storage Proteins ◽  
Paraveinal Mesophyll ◽  
Lytic Function ◽  
Metabolic Conditions ◽  
Glycine Max L ◽  
Soybean Leaves ◽  
And Storage ◽  
Lytic Compartment

Antibodies raised against tonoplast intrinsic proteins (TIPs) were used to probe the functional status of the soybean [Glycine max (L.) Merr.] paraveinal mesophyll (PVM) vacuole during changes in nitrogen metabolism within the leaf. Young plants grown under standard conditions had PVM vacuoles characterised by the presence of γ-TIP, which is indicative of a lytic function. When plants were then subjected to shoot tip removal for a period of 15 d, forcing a sink-limited physiological condition, the γ-TIP marker diminished while the δ-TIP marker became present in the PVM vacuole, indicating the conversion of the PVM vacuole to a storage function. When the shoot tips were allowed to regrow, the γ-TIP marker again became dominant demonstrating the reversion of these PVM vacuoles back to a lytic compartment. The changes in TIP markers correlated with the accumulation of vegetative storage proteins and vegetative lipoxygenases, proteins implicated in nitrogen storage and assimilate partitioning. This research suggests that the PVM vacuole is able to undergo dynamic conversion between lytic and storage functions and further implicates this cell layer in assimilate storage and mobilisation in soybeans.

Soybean vegetative lipoxygenases are not vacuolar storage proteins

2011 ◽  
Vol 38 (10) ◽  
pp. 778 ◽  
Author(s):  
Glenn W. Turner ◽  
Howard D. Grimes ◽  
B. Markus Lange
Keyword(s):  
Storage Proteins ◽  
Tissue Level ◽  
Protein Bodies ◽  
Specific Antibodies ◽  
Vegetative Storage Proteins ◽  
Paraveinal Mesophyll ◽  
Cast Doubt ◽  
Sink Limitation ◽  
Immuno Cytochemistry

The paraveinal mesophyll (PVM) of soybean is a distinctive uniseriate layer of branched cells situated between the spongy and palisade chlorenchyma of leaves that contains an abundance of putative vegetative storage proteins, Vspα and Vspβ, in its vacuoles. Soybean vegetative lipoxygenases (five isozymes designated as Vlx(A–E)) have been reported to co-localise with Vsp in PVM vacuoles; however, conflicting results regarding the tissue-level and subcellular localisations of specific Vlx isozymes have been reported. We employed immuno-cytochemistry with affinity-purified, isozyme-specific antibodies to reinvestigate the subcellular locations of soybean Vlx isozymes during a sink limitation experiment. VlxB and VlxC were localised to the cytoplasm and nucleoplasm of PVM cells, whereas VlxD was present in the cytoplasm and nucleoplasm of mesophyll chlorenchyma (MC) cells. Label was not associated with storage vacuoles or any evident protein bodies, so our results cast doubt on the hypothesis that Vlx isozymes function as vegetative storage proteins.

scholarly journals Examining pathways of iron and sulfur acquisition, trafficking, deployment, and storage in mineral-grown methanogen cells

2021 ◽  
Author(s):  
Devon Payne ◽  
Eric M. Shepard ◽  
Rachel L. Spietz ◽  
Katherine Steward ◽  
Sue Brumfield ◽  
...  
Keyword(s):  
Iron Sulfide ◽  
Storage Proteins ◽  
Spectral Feature ◽  
Methanogenic Archaea ◽  
Sulfide Mineral ◽  
Methanococcus Voltae ◽  
Fe Content ◽  
And Storage ◽  
Fe Acquisition ◽  
Excess Fe

Methanogens have a high demand for iron (Fe) and sulfur (S); however, little is known of how they acquire, deploy, and store these elements and how this, in turn, affects their physiology. Methanogens were recently shown to reduce pyrite (FeS 2 ) generating aqueous iron-sulfide (FeS (aq) ) clusters that are likely assimilated as a source of Fe and S. Here, we compare the phenotype of Methanococcus voltae when grown with FeS 2 or ferrous iron (Fe(II)) and sulfide (HS - ). FeS 2 -grown cells are 33% smaller yet have 193% more Fe than Fe(II)/HS - -grown cells. Whole cell EPR revealed similar distributions of paramagnetic Fe, although FeS 2 -grown cells showed a broad spectral feature attributed to intracellular thioferrate-like nanoparticles. Differential proteomic analyses showed similar expression of core methanogenesis enzymes, indicating that Fe and S source does not substantively alter the energy metabolism of cells. However, a homolog of the Fe(II) transporter FeoB and its putative transcriptional regulator DtxR were up-expressed in FeS 2 -grown cells, suggesting that cells sense Fe(II) limitation. Two homologs of IssA, a protein putatively involved in coordinating thioferrate nanoparticles, were also up-expressed in FeS 2 -grown cells. We interpret these data to indicate that, in FeS 2 -grown cells, DtxR cannot sense Fe(II) and therefore cannot down-regulate FeoB. We suggest this is due to the transport of Fe(II) complexed with sulfide (FeS (aq) ) leading to excess Fe that is sequestered by IssA as a thioferrate-like species. This model provides a framework for the design of targeted experiments aimed at further characterizing Fe acquisition and homeostasis in M. voltae and other methanogens. IMPORTANCE FeS 2 is the most abundant sulfide mineral in the Earth’s crust and is common in environments inhabited by methanogenic archaea. FeS 2 can be reduced by methanogens, yielding aqueous FeS (aq) clusters that are thought to be a source of Fe and S. Here, we show that growth of Methanococcus voltae on FeS 2 results in smaller cell size and higher Fe content per cell, with Fe likely stored intracellularly as thioferrate-like nanoparticles. Fe(II) transporters and storage proteins were up-regulated in FeS 2 -grown cells. These responses are interpreted to result from cells incorrectly sensing Fe(II) limitation due to assimilation of Fe(II) as FeS (aq) . These findings have implications for our understanding of how Fe/S availability influences methanogen physiology and the biogeochemical cycling of these elements.

scholarly journals Water Stress and Storage-protein Degradation during Germination of Impatiens Seed

1991 ◽  
Vol 116 (2) ◽  
pp. 302-306 ◽  
Author(s):  
Mehrassa Khademi ◽  
David S. Koranski ◽  
David J. Hannapel ◽  
Allen D. Knapp ◽  
Richard J. Gladon
Keyword(s):  
Water Stress ◽  
Storage Proteins ◽  
Dry Weight ◽  
Insoluble Fraction ◽  
Weight Basis ◽  
Optimum Conditions ◽  
Fresh Weight ◽  
Soluble Protein Fraction ◽  
Molecular Weights ◽  
And Storage

Water uptake by impatiens (Impatiens wallerana Hook. f. cv. Super Elfin Coral) seeds was measured as an increase in fresh weight every 24 hours during 144 hours of germination. Seeds absorbed most of the water required for germination within 3 hours of imbibition and germinated at 60% to 67% moisture on a dry-weight basis. Germination started at 48 hours and was complete by 96 hours at 25C. Water stress of -0.1, -0.2, -0.4, and -0.6 MPa, induced by polyethylene glycol 8000, reduced germination by 13%, 49%, 91%, and 100%, respectively, at 96 hours. Under the same water-stress conditions, increases in fresh weight were inhibited by 53%, 89%, 107%, and 106%, respectively. Three distinct groups of storage proteins were present in dry seed; their estimated molecular weights were 1) 35, 33, and 31 kDa; 2) 26, 23, and 21 kDa; and 3) two bands <14 kDa. Major depletion of storage proteins coincided with the completion of germination. Water potentials that inhibited germination also inhibited degradation of storage proteins. During germination under optimum conditions, the soluble protein fraction increased, coinciding with a decrease in the insoluble fraction.

Sign in / Sign up

Export Citation Format

Share Document