• The Korean Journal of Physiology and Pharmacology
• /
• v.7 no.4
• /
• pp.211-215
• /
• 2003

To examine the localization pattern of phospholipase D2 (PLD2) in the pancreatic islet (the islet of Langerhans) depending on species, we conducted a morphological experiment in the rat and guinea pig. Since individual islets display a typical topography with a central core of B cell mass and a peripheral boundary of A, D, and PP cells, double immunofluorescent staining with a panel of antibodies was performed to identify PLD2-immunoreactive cells in the islets PLD2 immunoreactivity was mainly present in A and PP cells of the rat pancreatic islets. And yet, in the guinea pig, PLD2 immunoreactivity was exclusively localized in A cells, and not in PP cells. These findings suggest a possibility that PLD2 is mainly located in A cells of rodent pancreatic islets, and that the existence of PLD2 in PP cells is not universal in all species. Based on these results, it is suggested that PLD2 may play a significant role in the function of A and/or PP cells via a PLD-mediated signaling pathway.

• Toxicological Research
• /
• v.21 no.4
• /
• pp.291-295
• /
• 2005

To define the effect of silica on the stimulator of signaling pathway, we studied the phospholipase D (PLD) activity in the Rat2 fibroblasts. Silica stimulated the accumulation of labeled $[^3H]$ phosphatidylethanol$([^3H]\;PEt)$ in a time- and concentration-dependent manner. This Silicainduced PLD activity was partially attenuated by the pretreatment with U73122 (phospholipase C inhibitor), genistein (protein tyrosine kinase inhibitor), PD 98056 (MEK inhibitor) and mepacrine (phospholipase $A_2$ inhibitor). But, sphingosine (protein kinase C inhibitor) and DPI (NADPH reductase inhibitor) had not effect the PLD activity. Silica also increased the PLD activity about four fold, which imply that the PLD activity is more influenced by the mobilization of PLD than other signaling mediators. The PLD activity also partially inhibited calcium chelator EGTA or/and BAPTA/AM compared to silica. Finally, we concluded that a silica-stimulated phospholipase D activity is present in the Rat2 fibroblasts and is modulated by combination of various signaling mediators.

• Journal of fish pathology
• /
• v.21 no.1
• /
• pp.1-11
• /
• 2008

We report the existence of new type of phosphatidylcholine-hydrolyzing phospholipase D (PLD), which has been characterized and partially purified in the scuticociliate, Uronema marinum. The enzyme from partial purification showed that it was existed in membrane fraction and was a neutral PLD, which catalyzed both transphosphatidylation and hydrolysis reaction. The activity of partially purified membrane-bound PLD was also found to be optimal at pH 7.0-7.5 for 2 hours at 37℃ and depended strictly on the presence of Ca2+ (2.5 mM) and Mg2+ (1.6 mM). Immunoblot analysis indicated that the enzyme was distinct from hPLD1 (human PLD1) and hPLD2 (human PLD2) because it was not recognized by a polyclonal antibody raised to the 12 terminal amino acid of these enzymes. We also found that the membrane-bound PLD is a PIP2-dependent PLD and that GTP-binding proteins are not implicated in the regulation of this enzyme: This enzyme activity is markedly stimulated by phosphatidylinositol 4,5-bisphosphate (PIP2) but not by the small G-protein Arf and GTPrS. In addition, this enzyme was capable of hydrolyzing phosphatidylcholine (PC) but not phosphatidylethanolamine (PE), implying that PC was a preferred substrate.

• Journal of Radiation Protection and Research
• /
• v.35 no.1
• /
• pp.1-5
• /
• 2010

This study concerning the surface dose of eye and thyroid from panoramagraphy used thermoluminescent dosimeter (TLD) and photoluminescent dosimeter (PLD) to take measurements at ten hospitals in the Gwangju metropolitan area. The recommendations from ICRP 60 and ICRP 73 on the allowance standard for eye are 15 mSv and for thyroid is 1 mSv. The left eye TLD and PLD values are 0.19 mSv and 0.24 mSv respectively. The right eye TLD and PLD values are 0.23 mSv and 0.25 mSv respectively. Thyroid TLD and PLD values are 0.08 mSv and 0.25 mSv respectively and did not exceed the allowance standards(p<0.001). Also comparisons are made between TLD and PLD for each organ and PLD has higher dose measurements than TLD. There are statistically significant differences in left eye measurements and thyroid measurements (p<0.01). There is no significant difference in measurements for the right eye (p>0.05). The TLD and PLD measured dose from panoramagraphy instruments on eyes and thyroid from each hospital did not exceed the recommended dose from ICRP 60 for surface dose measurements. However, due to the probability of influence, consideration should be made for all levels of dose.

• Journal of radiological science and technology
• /
• v.42 no.1
• /
• pp.47-51
• /
• 2019

This study was conducted from July 1 to September 30, 2018 using Optically Stimulated Luminescence Dosimeter(OSLD) and photoluminescent glass dosimeter(PLD) to measure the 3-month exposure dose and the cumulative dose in the active working area of the nuclear medicine worker Respectively. As a result, the cumulative dose for three months in the worker and work area was measured as 1.97 mSv and 2.02 mSv in the PLD. The mean surface dose and the mean depth dose of the OSLD were measured to be 2.04 mSv. The difference in the total surface dose measured by the PLD and the OSLD was 0.66mSv and the total mean surface dose was 0.07mSv. The difference between the total depth dose and the total depth dose was 0.1mSv and 0.02mSv, respectively. It was found that the dose value of the OSLD was higher than that of the PLD. In addition, it was found that the maximum difference of 0.01mSv was observed between the PLD and the OSLD of the worker. For the dose measurement of the two dosimetry systems, there was no significant difference between the PLD and the OSLD in the surface dose of 0.239 (p>0.05). Also, the significance of PLD and OSLD in the deep dose was 0.109, which was not statistically significant (p>0.05).

• Microbiology and Biotechnology Letters
• /
• v.22 no.4
• /
• pp.333-339
• /
• 1994

In order to screen microorganisms producing phospholipase D (PLD) [EC 3.1.4.4], culture broths of about 900 strains of soil bacteria were subjected to examine for the PLD activity. When the hydrolytic activity of PLD (H-activity) in the supernatant was determined, 64 strains produced PLD more than 0.3 unit/ml and all of them were actinomycetes. Among 26 culture broths tested, 6 ones had transphosphatidylation activity (T-activity) of 30~68%. When the strains except one were cultivated on 3 different media at 30$\circ$C for 3 days under aerobic condition, strain # 1090 on medium B (yeast extract 1%, peptone 1%, glucose 1.5%, glycerol 1%, CaCO$_{3}$ 0.4%, and pH 7.2) produced PLD with much higher H- and T-activity, which were 8.3 units/ml and 76.3%, respectively. Subsequently, time course of PLD production of the strain # 1090 during cultivation with aeration of 1 v/v/m and agitation of 400 rpm at 30$\circ$C for 5 days on medium B in jar fermentor was investigated. H-activty of PLD reached almost maximum (about 9 units/ml) after 32 hours and maximal T-activity was found to be about 80%.

• Biomedical Science Letters
• /
• v.15 no.4
• /
• pp.287-293
• /
• 2009

Phospholipase D (PLD) is an enzyme hydrolyzing phosphatidylcholine to phosphatidic acid (PA) and choline. We investigated the involvement of PLD1 in the uptake of norepinephrine (NE) in PC12 cells, pheochromocytoma cells. NE uptake was specific in PC12 cells because nomifensine, a specific blocker of NE transporter, blocked NE uptake. Inhibition of PLD function in PC12 cells by the treatment of butanol suppressed the NE uptake. In contrast, overexpression of PLD1 in PC12 cells increased NE uptake efficiently. These results suggest that PLD activity is involved in NE uptake. We explored the action mechanism of PLD in NE uptake. PA phosphatase inhibitor, propranolol, blocks the formation of PKC activator diacylglycerol from PA. Propranolol treatment to PC12 cells blocked dramatically the uptake of NE. Specific PKC inhibitors, GF109203X and Ro31-8220, blocked NE uptake. Taken together, we suggest for the first time that PLD1 activity is involved in NE uptake via the activation of PKC.

• Microbiology and Biotechnology Letters
• /
• v.32 no.1
• /
• pp.78-83
• /
• 2004

In order to screen microorganisms producing phopholipase D (PLD) had high transphosphatidylation activity, about 1,000 Actinomycetes strains were isolated from the 63 soil samples, collected over 6 local area in Korea. When the hydrolytic activity in the supernatant was determined, 131 strains produced PLD more than 0.3U/$m\ell$. Among 131 culture broths tested, 23 ones had transphosphatidylation activity higher than 20% and finally one strain (Actinomycetes KF923), which had highest hydrolytic and transphophadylation activity, was selected. Actinomycetes KF923 showed the highest hydrolytic activity (13U/$m\ell$) and phosphatidylation activity (95%) after 48 h fermentation using the P medium (yeast extract 1%, peptone 1%, glucose 1.5%, glycerol 1%, $CaCO_3$ 0.4%, pH 7.2). PLD was purified from the culture broth of Actinomycetes KF923 and the specific activity of purified PLD was 567U/mg. The molecular weight of PLD was about 55kD and the optimum pH and temperature were pH 6.0 and $60^{\circ}C$, respectively. The stability of PLD toward pH and temperature were high around pH 8.0 and below $40^{\circ}C$ Special metal ions were not necessary to the PLD activity.

• Clean Technology
• /
• v.21 no.4
• /
• pp.224-228
• /
• 2015

Phospholipase D (PLD) was immobilized on a submicro-porous membrane through covalent immobilization. The immobilization was conducted on the porous membrane surface with the treatment of polyethyleneimine, glutaraldehyde, and the anhydrase, in sequence. The immobilization was confirmed using X-ray photon spectrometer. The pH values of phosphatidylcholine (PC) dispersion solution with buffer were monitored with respect to time to calculate the catalytic activities of PC for free and immobilized PLD. The catalytic rate constant values for free PLD, immobilized PLD on polystyrene nanoparticles, and immobilized PLD on a porous cellulose acetate membrane were 0.75, 0.64, and 0.52 s^-1, respectively. Reusability was studied up to 10 cycles of PC hydrolysis. The activity for the PLD immobilized on the membrane was kept to 95% after 10 cycles, and comparable to the PLD on the nanoparticles. The stabilities for heat and storage were also investigated for the three cases. The results suggested that the PLD immobilized on the membrane had the least loss rate of the activity compared to the others. From these studies, the porous membrane was feasible as a carrier for the PLD immobilization in the production of phosphatidic acid.

• Journal of the Korean Chemical Society
• /
• v.54 no.2
• /
• pp.208-214
• /
• 2010

In the presence of alcohol, phospholipase D (PLD) is known to perform transphosphatidylation activity, during which the overall reaction rate of PLD increased. To elucidate the reaction mechanism of transphosphatidylation further, we investigated rate constants of transphosphatidylation reaction of the purified ${\alpha}$-type PLD from cabbage in the presence of various alcohols. The second-oder rate constants of PLD transphosphatidylation showed a large increase with the primary alcohols examined as expected. In the case of butanol we observed the second-oder rate constant of $33.33{\pm}1.33M^{-1}sec^{-1}$. This second-order rate constant of transphosphatidylation was as 400 times greater as the second-order hydrolysis rate constant of $0.078M^{-1}sec^{-1}$ which was adjusted for the water concentration. A linear free energy relationship between the $pK_a$ of alcohol and transphosphatidylation rate gives a Br${\o}$nsted slope of ${\beta}_{nu}$ = 0.12 ${\pm}$ 0.03. This small ${\beta}_{nu}$ value implicates that the transition state of break down of phosphatidyl-enzyme intermediate (E-P) is likely dissociative. Finally, a reaction mechanism of cabbage PLD is suggested on the basis of our results presented here and the histidine residue known to be located in the active site of cabbage PLD.