The possible role of lipid intermediates in the synthesis of ?-glucans by a membrane fraction from pollen tubes of Petunia hybrida

Planta ◽  
1979 ◽  
Vol 144 (5) ◽  
pp. 443-450 ◽  
Author(s):  
J. P. F. G. Helsper
Keyword(s):  
Membrane Fraction ◽  
Petunia Hybrida ◽  
Pollen Tubes

The possible role of embryo sac degeneration in yield reduction of summer turnip rape cultivar Candle

1995 ◽  
Vol 75 (3) ◽  
pp. 595-598
Author(s):  
Xiuying Tian ◽  
L. Van Caeseele ◽  
M. J. Sumner
Keyword(s):  
Brassica Rapa ◽  
Seed Set ◽  
Embryo Sac ◽  
Pollen Tubes ◽  
Yield Reduction ◽  
Turnip Rape ◽  
Key Words:Brassica

When pollination occurred within 24 h after anthesis, 69.2% of the pods of Brassica rapa cultivar Candle contained at least 50% fertilized ovules. If pollination occurred later than 4 d after anthesis, an occasional ovule near the base of the pistil was fertilized; however, no significant seed set was observed. Pollen tubes were observed entering the locules of the ovary from pollinations carried out as late as 5 d after anthesis. At 3 d after anthesis, in unpollinated flowers, a general deterioration of the embryo-sac contents began and gradually increased to include integumentary cells by 6 d after anthesis. Some ovules swelled as though they were fertilized, but no embryos were present. The results suggest that yield reductions in this species may occur because of the reduction of fertilization potential through rapid degeneration of embryo sacs following anthesis. Key words:Brassica rapa, embryo sac, yield

Activation of Rho signaling contributes to lysophosphatidic acid-induced contraction of intact ileal smooth muscle of guinea-pig

2000 ◽  
Vol 78 (9) ◽  
pp. 729-736 ◽  
Author(s):  
Mayumi Mori ◽  
Hiromi Tsushima
Keyword(s):  
Smooth Muscle ◽  
Guinea Pig ◽  
Lysophosphatidic Acid ◽  
Membrane Fraction ◽  
Smooth Muscles ◽  
Rho Kinase ◽  
Specific Inhibitor ◽  
High K ◽  
Rho A

To elucidate the possible role of Rho A/Rho-kinase on lysophosphatidic acid (LPA)-induced contraction in intact guinea-pig ileal smooth muscle, we examined effects of pretreatment with a specific inhibitor of Rho-kinase (Y-27632) on the LPA-induced contraction and MLC20 phosphorylation. In addition, we investigated whether LPA actually elicits an activation of Rho A by studying subcellular distribution of Rho A in unstimulated and stimulated smooth muscles by LPA. LPA induced a less intense, but sustained, contraction compared with ACh, and was accompanied by significant increases in MLC20 phosphorylation. The effects of LPA on tension and MLC20 phosphorylation were inhibited by Y-27632. The ACh-induced contraction, but not increases in MLC20 phosphorylation, was partially inhibited by Y-27632. High K+-induced contraction was unaffected by the inhibitor. LPA stimulated translocation of Rho A from the cytosol to the membrane fraction of the muscle. Translocation of Rho A was also induced by ACh and high K+. These results suggest that LPA-induced contraction of intact ileal smooth muscle is dominated through activation of Rho A and Rho-kinase and subsequent increases in MLC20 phosphorylation.Key words: lysophosphatidic acid, Rho, Rho-kinase, ileal smooth muscle.

The function of glycosyl phosphoinositides in hormone action

1988 ◽  
Vol 320 (1199) ◽  
pp. 345-358 ◽  
Keyword(s):  
Membrane Fraction ◽  
Inositol Phosphate ◽  
Second Messengers ◽  
Chemical Substance ◽  
Hormone Action ◽  
Glycosyl Phosphatidylinositol ◽  
Molecular Events ◽  
Fat Liver ◽  
Hydrolysis Of

The molecular events involved in the cellular actions of insulin remain unexplained. Some of the acute actions of the hormone may be due to the intracellular generation of a chemical substance which modulates certain enzyme activities. Such an enzymemodulating substance has been identified as an inositol phosphate-glycan, produced by the insulin-sensitive hydrolysis of a glycosyl-phosphatidylinositol (glycosyl-Ptdlns) precursor. This precursor glycolipid is structurally similar to the glycosylphosphoinositide membrane protein anchor. The exposure of fat, liver or muscle cells to insulin results in the hydrolysis of glycosyl-Ptdlns, giving rise to the inositol phosphate glycan and diacylglycerol. This hydrolysis reaction is catalysed by a glycosyl-PtdIns-specific phospholipase C. This enzyme has been characterized and purified from a plasma membrane fraction of liver. This reaction also results in the acute release of certain glycosyl-Ptdlns-anchored proteins from the cell surface. Elucidation of the functional role of glycosyl-phosphoinositides in the generation of second messengers or the release of proteins may provide further insights into the pleiotropic nature of insulin action.

Role of a callose synthase zymogen in regulating wall deposition in pollen tubes of Nicotiana alata Link et Otto

Planta ◽  
1999 ◽  
Vol 208 (4) ◽  
pp. 528-538 ◽  
Author(s):  
Huijuan Li ◽  
Antony Bacic ◽  
Steve M. Read
Keyword(s):  
Pollen Tubes ◽  
Nicotiana Alata ◽  
Callose Synthase ◽  
Wall Deposition

scholarly journals Phosphorylated HSP27 essential for acetylcholine-induced association of RhoA with PKCα

2004 ◽  
Vol 286 (4) ◽  
pp. G635-G644 ◽  
Author(s):  
Suresh B. Patil ◽  
Mercy D. Pawar ◽  
Khalil N. Bitar
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Muscle Contraction ◽  
Membrane Fraction ◽  
Muscle Cells ◽  
Smooth Muscle Contraction ◽  
Cell Length ◽  
Sustained Contraction ◽  
Hsp 27

Reorganization of the cytoskeleton and association of contractile proteins are important steps in modulating smooth muscle contraction. Heat shock protein (HSP) 27 has significant effects on actin cytoskeletal reorganization during smooth muscle contraction. We investigated the role of phosphorylated HSP27 in modulating acetylcholine-induced sustained contraction of smooth muscle cells from the rabbit colon by transfecting smooth muscle cells with phosphomimic (3D) or nonphosphomimic (3G) HSP27. In 3G cells, the initial peak contractile response at 30 s was inhibited by 25% (24.0 ± 4.5% decrease in cell length, n = 4). The sustained contraction was greatly inhibited by 75% [9.3 ± .9% decreases in cell length ( n = 4)]. Furthermore, in 3D cells, translocation of both PKCα and of RhoA was greatly enhanced and resulted in a greater association of PKCα-RhoA in the membrane fraction. In 3G transfected cells, PKCα and RhoA failed to translocate in response to stimulation with acetylcholine, resulting in an inhibition of association of PKCα-RhoA in the membrane fraction. Studies using GST-RhoA fusion protein indicate that there is a direct association of RhoA with PKCα and with HSP27. The results suggest that phosphorylated HSP27 plays a crucial role in the maintenance of association of PKCα-RhoA in the membrane fraction and in the maintenance of acetylcholine-induced sustained contraction.

Sign in / Sign up

Export Citation Format

Share Document