Sucrose transport-related genes are expressed in both maternal and filial tissues of developing wheat grains

2000 ◽  
Vol 27 (11) ◽  
pp. 1009 ◽  
Author(s):  
Neil Bagnall ◽  
Xin-Ding Wang ◽  
Graham N. Scofield ◽  
Robert T. Furbank ◽  
Christina E. Offler ◽  
...  
Keyword(s):  
Membrane Transport ◽  
Plasma Membranes ◽  
Triticum Turgidum ◽  
Proton Pumping ◽  
Transfer Cells ◽  
Sucrose Transport ◽  
Wheat Grains ◽  
Nucellar Projection ◽  
Vascular Parenchyma ◽  
P Type

In developing wheat grains (Triticum turgidum var. durum cv. Fransawi), post-sieve element transport of phloem-imported photoassimilates (sucrose) includes membrane transport, to and from the grain apoplasm, between symplasmically-isolated maternal and filial tissues. The cellular location and mechanism of these membrane transport steps were explored during rapid grain fill. Genomic Southern analysis indicated the presence of a multigene family of sucrose/H + symporters (SUTs). One or more SUTs were highly expressed in developing grains, as were P-type H + /ATPase(s) and a sucrose binding protein (SBP). Transcripts of these genes were detected in vascular parenchyma, nucellar projection and aleurone cells. Antibodies, raised against a SUT, an H + /ATPase and a SBP, were selectively bound to plasma membranes of vascular parenchyma cells, nucellar projection transfer cells and modified aleurone/sub-aleurone transfer cells. The nucellar projection transfer cells and modified aleurone/sub-aleurone transfer cells exhibited strong proton pumping activity. In contrast, SUT transport function was restricted to filial tissues containing modified aleurone/sub-aleurone transfer cells. Based on these findings, we conclude that SUTs expressed in maternal tissues do not function as sucrose/H + symporters. Membrane exchange from nucellar projection transfer cells to the endosperm cavity occurs by an as yet unresolved mechanism. Sucrose uptake from the endosperm cavity into filial tissues is mediated by a SUT localised to plasma membranes of the modified aleurone/sub-aleurone transfer cells.

scholarly journals Structure and histochemistry of sorghum caryopsis in relation to grain-filling

2020 ◽  
Vol 12 (4) ◽  
pp. 852-868
Author(s):  
S. RAVI SHANKAR ◽  
P. DAYANANDAN
Keyword(s):  
Single Layer ◽  
Grain Filling ◽  
Vascular Supply ◽  
Transfer Cells ◽  
Stages Of Development ◽  
Nucellar Projection ◽  
Wall Ingrowth ◽  
Vascular Parenchyma ◽  
C3 Grasses ◽  
Pigment Strand

Anatomical and histochemical studies of ovary and caryopsis of sorghum reveal the importance of the chalazal complex in transporting nutrients from maternal sources to the filial diploid embryo and triploid endosperm. The presence of starch, protein, lipid, Ca, K, Mg, and Fe in various tissues at different stages of development can be revealed by a variety of histochemical techniques. Vascular supply ends at the base of the ovary and transport occurs through vascular parenchyma, pigment strand and nucellar projection where symplastic continuity is broken. Nutrients unloaded into an apoplastic placental sac then enter the endosperm and embryo through the aleurone transfer cells. The later possess characteristic wall ingrowth. The single layer of aleurone surrounding the endosperm may also help in transport during later stages of grain-filling. Grain-filling in C4 sorghum is compared with other C4 and C3 grasses showing the variety of strategies evolved to transport nutrients into filial tissues. Standardization of terminologies to describe the tissues of the crease region will help in further research and communication.

scholarly journals Energized Ca2+ transport by hepatopancreatic basolateral plasma membranes of Homarus americanus.

1998 ◽  
Vol 201 (2) ◽  
pp. 211-220 ◽  
Author(s):  
Z Zhuang ◽  
G A Ahearn
Keyword(s):  
Transport System ◽  
Carrier Transport ◽  
Plasma Membranes ◽  
Basolateral Membrane ◽  
Membrane Vesicles ◽  
Homarus Americanus ◽  
Molt Cycle ◽  
Apparent Affinity ◽  
Carrier Mechanism ◽  
P Type

Ca2+ transport by hepatopancreatic basolateral membrane vesicles of Atlantic lobster (Homarus americanus) occurred by at least two independent processes: (1) an ATP-dependent carrier transport system, and (2) a Na+-gradient-dependent carrier mechanism. The sensitivity of ATP-dependent Ca2+ transport to vanadate indicated that it was probably due to a P-type ATPase. This system exhibited an extremely high apparent affinity for Ca2+ (Kt=65.28+/-14.39 nmol l-1; Jmax=1. 07+/-0.06 pmol microg-1 protein 8 s-1). The Na+-gradient-dependent carrier transport system exhibited the properties of a Ca2+/Na+ antiporter capable of exchanging external Ca2+ with intravesicular Na+ or Li+. Kinetic analysis of the Na+-dependence of the antiport indicated that at least three Na+ were exchanged with each Ca2+ (n=2. 91+/-0.22). When Li+ replaced Na+ in exchange for 45Ca2+, the apparent affinity for Ca2+ influx was not significantly affected (with Na+, Kt=14.57+/-5.02 micromol l-1; with Li+, Kt=20.17+/-6.99 micromol l-1), but the maximal Ca2+ transport velocity was reduced by a factor of three (with Na+, Jmax=2.72+/-0.23 pmol microg-1 protein 8 s-1; with Li+, Jmax=1.03+/-0.10 pmol microg-1 protein 8 s-1). It is concluded that Ca2+ leaves hepatopancreatic epithelial cells across the basolateral membrane by way of a high-affinity, vanadate-sensitive Ca2+-ATPase and by way of a low-affinity Ca2+/Na+ antiporter with an apparent 3:1 exchange stoichiometry. The roles of these transporters in Ca2+ balance during the molt cycle are discussed.

Nucellar projection transfer cells in the developing wheat grain

PROTOPLASMA ◽  
1994 ◽  
Vol 182 (1-2) ◽  
pp. 39-52 ◽  
Author(s):  
H. L. Wang ◽  
C. E. Offler ◽  
J. W. Patrick
Keyword(s):  
Transfer Cells ◽  
Wheat Grain ◽  
Nucellar Projection

scholarly journals Direct observation of proton pumping by a eukaryotic P-type ATPase

Science ◽  
2016 ◽  
Vol 351 (6280) ◽  
pp. 1469-1473 ◽  
Author(s):  
S. Veshaguri ◽  
S. M. Christensen ◽  
G. C. Kemmer ◽  
G. Ghale ◽  
M. P. Moller ◽  
...  
Keyword(s):  
Direct Observation ◽  
Proton Pumping ◽  
P Type

scholarly journals Role for a P-type H+-ATPase in the acidification of the endocytic pathway of Trypanosoma cruzi

2005 ◽  
Vol 392 (3) ◽  
pp. 467-474 ◽  
Author(s):  
Mauricio Vieira ◽  
Peter Rohloff ◽  
Shuhong Luo ◽  
Narcisa L. Cunha-E-Silva ◽  
Wanderley De Souza ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Trypanosoma Cruzi ◽  
Subcellular Fractionation ◽  
Etiologic Agent ◽  
Proton Pumping ◽  
Endocytic Pathway ◽  
Immunogold Electron Microscopy ◽  
Intermediate Form ◽  
Confocal Immunofluorescence Microscopy ◽  
P Type

Previous studies in Trypanosoma cruzi, the etiologic agent of Chagas disease, have resulted in the cloning and sequencing of a pair of tandemly linked genes (TcHA1 and TcHA2) that encode P (phospho-intermediate form)-type H+-ATPases with homology to fungal and plant proton-pumping ATPases. In the present study, we demonstrate that these pumps are present in the plasma membrane and intracellular compartments of three different stages of T. cruzi. The main intracellular compartment containing these ATPases in epimastigotes was identified as the reservosome. This identification was achieved by immunofluorescence assays and immunoelectron microscopy showing their co-localization with cruzipain, and by subcellular fractionation and detection of their activity. ATP-dependent proton transport by isolated reservosomes was sensitive to vanadate and insensitive to bafilomycin A1, which is in agreement with the localization of P-type H+-ATPases in these organelles. Analysis by confocal immunofluorescence microscopy revealed that epitope–tagged TcHA1-Ty1 and TcHA2-Ty1 gene products are localized in the reservosomes, whereas the TcHA1-Ty1 gene product is additionally present in the plasma membrane. Immunogold electron microscopy showed the presence of the H+-ATPases in other compartments of the endocytic pathway such as the cytostome and endosomal vesicles, suggesting that in contrast with most cells investigated until now, the endocytic pathway of T. cruzi is acidified by a P-type H+-ATPase.

Vacuolar-type H(+)-ATPases are functionally expressed in plasma membranes of human tumor cells

1993 ◽  
Vol 265 (4) ◽  
pp. C1015-C1029 ◽  
Author(s):  
R. Martinez-Zaguilan ◽  
R. M. Lynch ◽  
G. M. Martinez ◽  
R. J. Gillies
Keyword(s):  
Plasma Membrane ◽  
Tumor Cells ◽  
Cell Lines ◽  
Mammalian Cells ◽  
Plasma Membranes ◽  
Human Tumor ◽  
Atp Depletion ◽  
Second Phase ◽  
Bafilomycin A1 ◽  
P Type

Mammalian cells generally regulate their intracellular pH (pHi) via collaboration between Na(+)-H+ exchanger and HCO3- transport. In addition, a number of normal mammalian cells have been identified that express H(+)-adenosinetriphosphatases (ATPases) in their plasma membranes. Because tumor cells often maintain a high pHi, we hypothesized that they might functionally express H(+)-ATPases in their plasma membranes. In the first phase of the present study, we screened 19 normal and tumorigenic human cell lines for the presence of plasmalemmal H(+)-ATPase activity using bafilomycin A1 to inhibit V-type H(+)-ATPase and Sch-28080 to inhibit P-type H(+)-K(+)-ATPase. Bafilomycin A1 decreased pHi in the six tumor cell lines with the highest resting pHi in the absence of HCO3-. Sch-28080 did not affect pHi in any of the human cells. Simultaneous measurement of pH in the cytoplasm and in the endosomes/lysosomes localized the activity of bafilomycin to the plasma membrane in three cell lines. In the second phase of this study, these three cell lines were shown to recover from NH4(+)-induced acid loads in the absence of Na+. This recovery was inhibited by N-ethylmaleimide, bafilomycin A1, and ATP depletion and was not significantly affected by vanadate, Sch-28080, or hexamethyl amiloride. These results indicate that a vacuolar type H(+)-ATPase is expressed in the plasma membrane of some tumor cells.

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