Functions of polyamine acetylation

1987 ◽  
Vol 65 (10) ◽  
pp. 2024-2035 ◽  
Author(s):  
Nikolaus Seiler
Keyword(s):  
Polyamine Metabolism ◽  
Cyclic Process ◽  
Precise Control ◽  
Polyamine Transport ◽  
Anionic Binding Sites ◽  
Polyamine Acetylation ◽  
Concentration Changes ◽  
High Level ◽  
Rate Limiting ◽  
Net Positive Charge

Acetylation is a means to decrease the net positive charge of the plyamines and thus liberate polyamines from anionic binding sites. The acetyl derivatives can be removed from the cells by transport and catabolism. Intracellular polyamine metabolism can be formulated as a cyclic process, which explains the transformation of one polyamine into another. As a net result, this pathway metabolizes (in an energy-requiring manner) methionine to 5′-deoxy-5′-methylthioadenosine and β-alanine, and thus appears to be futile. It is suggested that the cyclic process is necessary for the precise control of cellular polyamine concentrations, as it allows relatively rapid spermine and spermidine concentration changes, in spite of a slow basal turnover rate. For the regulation of cellular polyamine metabolism, two decarboxylases, L-ornithine decarboxylase and S-adenosyl-L-methionine decarboxylase; the cytosolic acetyl-CoA:spermidine/spermine N1-acetyltransferase; and a polyamine transport system are required. The activity of the nucelar acetyltransferase is assumed to be the rate-limiting enzyme of nuclear polyamine turnover. The complexity and high level of sophistication of polyamine regulation is strong evidence for the important functional significance of the natural polyamines.

scholarly journals Differential expression and regulation of Tdo2 during mouse decidualization

2013 ◽  
Vol 220 (1) ◽  
pp. 73-83 ◽  
Author(s):  
Dang-Dang Li ◽  
Ying-Jie Gao ◽  
Xue-Chao Tian ◽  
Zhan-Qing Yang ◽  
Hang Cao ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Differential Expression ◽  
Stromal Cells ◽  
Real Time Pcr ◽  
Mouse Uterus ◽  
Decidual Cells ◽  
High Level ◽  
Rate Limiting

Tryptophan 2,3-dioxygenase (Tdo2) is a rate-limiting enzyme which directs the conversion of tryptophan to kynurenine. The aim of this study was to examine the expression and regulation of Tdo2 in mouse uterus during decidualization. Tdo2 mRNA was mainly expressed in the decidua on days 6–8 of pregnancy. By real-time PCR, a high level of Tdo2 expression was observed in the uteri from days 6 to 8 of pregnancy, although Tdo2 expression was observed on days 1–8. Simultaneously, Tdo2 mRNA was also detected under in vivo and in vitro artificial decidualization. Estrogen, progesterone, and 8-bromoadenosine-cAMP could induce the expression of Tdo2 in the ovariectomized mouse uterus and uterine stromal cells. Tdo2 could regulate cell proliferation and stimulate the expression of decidual marker Dtprp in the uterine stromal cells and decidual cells. Overexpression of Tdo2 could upregulate the expression of Ahr, Cox2, and Vegf genes in uterine stromal cells, while Tdo2 inhibitor 680C91 could downregulate the expression of Cox2 and Vegf genes in uterine decidual cells. These data indicate that Tdo2 may play an important role during mouse decidualization and be regulated by estrogen, progesterone, and cAMP.

scholarly journals Interactive Virtual Humans in Real-Time Virtual Environment

2006 ◽  
Vol 5 (2) ◽  
pp. 15-24 ◽  
Author(s):  
Nadia Magnenat-Thalmann ◽  
Arjan Egges
Keyword(s):  
Real Time ◽  
Linear Representation ◽  
Virtual Humans ◽  
Precise Control ◽  
Ongoing Work ◽  
The Face ◽  
Input Motion ◽  
High Level ◽  
Joint Motions ◽  
Vast Area

In this paper, we will present an overview of existing research in the vast area of IVH systems. We will also present our ongoing work on improving the expressive capabilities of IVHs. Because of the complexity of interaction, a high level of control is required over the face and body motions of the virtual humans. In order to achieve this, current approaches try to generate face and body motions from a high-level description. Although this indeed allows for a precise control over the movement of the virtual human, it is difficult to generate a natural-looking motion from such a high-level description. Another problem that arises when animating IVHs is that motions are not generated all the time. Therefore a flexible animation scheme is required that ensures a natural posture even when no animation is playing. We will present MIRAnim, our animation engine, which uses a combination of motion synthesis from motion capture and a statistical analysis of prerecorded motion clips. As opposed to existing approaches that create new motions with limited flexibility, our model adapts existing motions, by automatically adding dependent joint motions. This renders the animation more natural, but since our model does not impose any conditions on the input motion, it can be linked easily with existing gesture synthesis techniques for IVHs. Because we use a linear representation for joint orientations, blending and interpolation is done very efficiently, resulting in an animation engine especially suitable for real-time applications

Biological treatability of a corn wet mill effluent

2002 ◽  
Vol 45 (12) ◽  
pp. 339-346 ◽  
Author(s):  
G. Eremektar ◽  
O. Karahan-Gul ◽  
F. Germirli-Babuna ◽  
S. Ovez ◽  
H. Uner ◽  
...  
Keyword(s):  
Biological Treatment ◽  
Rate Coefficient ◽  
Activated Sludge Process ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Metabolic Products ◽  
High Level ◽  
Biological Treatability ◽  
Rate Limiting ◽  
Hydrolysis Of

Corn wet mill effluents are studied in terms of their characteristics relevant for biological treatment. They have a high COD of mainly soluble and biodegradable nature, with practically no soluble inert components. They generate a relatively high level of soluble residual metabolic products, which affects the choice of the appropriate biological treatment and favors aerobic activated sludge process. Experimental assessment of process kinetics yields typical values. Hydrolysis of the slowly biodegradable COD, the rate limiting step for the utilization of substrate, is characterized by an overall rate coefficient, which is within the range commonly associated for the hydrolysis of starch.

scholarly journals A new method to quantify macroalgae and a practical sampler for experimentation in lotic habitats

2012 ◽  
Vol 72 (4) ◽  
pp. 853-857 ◽  
Author(s):  
AF. Tonetto ◽  
CK. Peres ◽  
CCZ. Branco
Keyword(s):  
Benthic Communities ◽  
Experimental Studies ◽  
Temporal Variations ◽  
Nondestructive Technique ◽  
Abiotic Conditions ◽  
Precise Control ◽  
Lotic Habitats ◽  
Precise Quantification ◽  
Lotic Environments ◽  
High Level

Experimental studies in rivers and streams are extremely difficult to run due to the fact that the conditions of these environments are very complex and provide a high level of heterogeneity, which hinders the precise control and standardization of variables. In this study, we present a practical sampler that was designed to make it easier to conduct research projects involving benthic communities of lotic environments, as well as a new nondestructive technique for quantification of the macroalgal communities typically found in these habitats. The sampler consists of an acrylic square tube in which water flows normally inside. This structure carries a removable glass plaque with a known area and can simulate various ecological situations by changing both biotic and abiotic conditions. Thus, it can mitigate the differences between environmental characteristics where each sampler is exposed. The new technique involves capturing digital images that can monitor a unique macroalgal community in development throughout time and a more precise quantification when compared with other techniques that are widely applied. The sampler is easy to build and the images simple to quantify, allowing the detection of spatial and temporal variations in richness and abundance of investigated communities.

scholarly journals Effects of controlled RAD52 expression on repair and recombination in Saccharomyces cerevisiae.

1991 ◽  
Vol 11 (4) ◽  
pp. 2013-2017 ◽  
Author(s):  
K J Dornfeld ◽  
D M Livingston
Keyword(s):  
Fold Increase ◽  
Mitotic Recombination ◽  
Protein Product ◽  
Wild Type ◽  
Recombination Rates ◽  
Plasmid Recombination ◽  
Gal1 Promoter ◽  
High Level ◽  
Rate Limiting ◽  
Mutant Cells

We have examined the effects of RAD52 overexpression on methyl methanesulfonate (MMS) sensitivity and spontaneous mitotic recombination rates. Cells expressing a 10-fold excess of RAD52 mRNA from the ENO1 promoter are no more resistant to MMS than are wild-type cells. Similarly, under the same conditions, the rate of mitotic recombination within a reporter plasmid does not exceed that measured in wild-type cells. This high level of expression is capable of correcting the defects of rad52 mutant cells in carrying out repair and recombination. From these observations, we conclude that wild-type amounts of Rad52 are not rate limiting for repair of MMS-induced lesions or plasmid recombination. By placing RAD52 under the control of the inducible GAL1 promoter, we find that induction results in a 12-fold increase in the fraction of recombinants within 4 h. After this time, the fraction increases less rapidly. When RAD52 expression is quickly repressed during induction, the amount of RAD52 mRNA decreases rapidly and no nascent recombinants are formed. This result suggests a short active half-life for the protein product. Induction of RAD52 in G1-arrested mutant cells also causes a rapid increase in recombinants, suggesting that replication is not necessary for plasmid recombination.

scholarly journals Effects of the S-adenosylmethionine decarboxylase inhibitor, 5′-{[(Z)-4-amino-2-butenyl]methylamino)-5′-deoxyadenosine, on cell growth and polyamine metabolism and transport in Chinese hamster ovary cell cultures

1994 ◽  
Vol 303 (1) ◽  
pp. 89-96 ◽  
Author(s):  
T L Byers ◽  
R S Wechter ◽  
R H Hu ◽  
A E Pegg
Keyword(s):  
Cell Growth ◽  
Transport System ◽  
Chinese Hamster Ovary ◽  
Cho Cells ◽  
Chinese Hamster ◽  
Ovary Cell ◽  
Polyamine Metabolism ◽  
Decarboxylase Inhibitor ◽  
Transport Activity ◽  
Polyamine Transport

The regulation of polyamine transport and the roles of polyamine transport and synthesis in cell growth were investigated using cultured Chinese hamster ovary (CHO) cells and CHOMG cells which are mutants lacking polyamine-transport activity. Metabolically stable methylated polyamine analogues were used to measure polyamine accumulation, and the irreversible S-adenosyl-L-methionine decarboxylase inhibitor, 5′-([(Z)-4-amino-2-butenyl]methylamino)-5′-deoxyadenosine (AbeAdo), was used to inhibit synthesis. Exposure to AbeAdo lead to a dose-dependent decrease in growth for both cell lines, although CHOMG cells were more sensitive. Intracellular putrescine levels were greatly increased in AbeAdo-treated CHO cells and to a lesser extent in CHOMG cells, whereas intracellular spermidine and spermine levels were substantially reduced in both. Treatment with AbeAdo increased putrescine content in the culture medium to a much greater extent in CHOMG cultures indicating that a portion of the excess putrescine synthesized in response to AbeAdo treatment is excreted, but that CHO cells salvage this putrescine whereas it is lost to CHOMG cells which cannot take up polyamines. AbeAdo treatment increased polyamine transport into CHO cells despite high intracellular putrescine, suggesting that spermidine and/or spermine, and not putrescine, are the major factors regulating transport activity. The accumulation of either 1-methylspermidine or 1,12-dimethylspermine was significantly increased by AbeAdo treatment. Accumulation was increased even further when protein synthesis was blocked by cycloheximide, indicating that a short-lived protein is involved in the regulation of polyamine uptake. In the presence of cycloheximide and AbeAdo or alpha-difluoromethylornithine, methylated polyamine derivatives accumulated to very high levels leading to cell death. These results show that the polyamine-transport system plays an important role in retaining intracellular polyamines and that down-regulation of the transport system in response to increased intracellular polyamine content is necessary to prevent accumulation of toxic levels of polyamines.

Short-interval absorption and metabolism of some amino acids in Trypanosoma gambiense

Parasitology ◽  
1972 ◽  
Vol 64 (3) ◽  
pp. 379-387 ◽  
Author(s):  
L. H. Chappell ◽  
G. C. Southworth ◽  
C. P. Read
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Short Interval ◽  
Cysteic Acid ◽  
Transaminase Activity ◽  
Glutamate Pyruvate Transaminase ◽  
Glutamate Pyruvate ◽  
High Level ◽  
Rate Limiting ◽  
Trypanosoma Gambiense

During 2 min incubations of Trypanosoma gambiense (bloodstream form) with [U-14C]glucose (1 mM) over 60% of absorbed label was detected in free alanine. In the presence of 12·5 mM unlabelled alanine, the amount of alanine synthesized from glucose was reduced by less than 10%. These data support previous observations on the high level of transaminase activity in African human trypanosomes.Alanine, aspartate and glutamate were metabolized to various other free amino acids whereas a significant amount of label derived from [14C]arginine could not be accounted for by amino acid assay.The sulphur containing amino acids, cysteic acid and taurine, were apparently synthesized from alanine, glutamate and arginine. The significance of these syntheses is poorly understood.Following incubations of trypanosomes for 2 min in exogenous amino acids the internal free pool became imbalanced due to accumulation and metabolism of the substrate amino acid.Evidence obtained indicated that the level of free endogenous glutamate may be rate limiting for the glutamate-pyruvate transaminase system.

scholarly journals Social Electrical Engineering: A Pathway for Better Undergraduate Education

2018 ◽  
Vol 5 (1) ◽  
pp. 13
Author(s):  
Amilton Costa Lamas ◽  
Anderson Gomes Domingues
Keyword(s):  
Engineering Students ◽  
Low Cost ◽  
Electrical Engineering ◽  
Cyclic Process ◽  
Communication Analysis ◽  
Professional Recognition ◽  
Electrical Engineers ◽  
White Cane ◽  
Social Capitals ◽  
High Level

As engineering skills becomes a commodity, electrical engineers’ programs are urged to adapt their pedagogical strategies do better prepared their graduates. The 21st century engineers are expected to have a strong technical background while being capable to work with people with different kinds of intellectual and social capitals, and to have a high level of cognitive flexibility. This article reports on the application of an information appropriation method, adopted by the Department of Electrical Engineering at PUC-Campinas, where activities on extension projects are simultaneously conducted along with the regularly schedule classes. The study case is related to the coplanning and cocreation of a technological white cane (proof of connect) between electrical engineering students, social technicians and the visually impaired. In the present case, the technicians were led to reinterpret, adapt and reinvent technology while contributing to the design and build of a low cost adaptive electronic sensing aid attachable to a white cane. The collaborative method, applied during conversation rounds, is based on a virtuous cyclic process which includes steps like information capture, validation, guidance and feedback. The engineering students, on the other hand, have the opportunity to develop their communication, analysis and interpretation skills in a way not available in the classroom. They also experience solving conflict situations and find creative uses and applications for they knowledge not otherwise foreseen. The participating students transformed information into knowledge through a dialogical experience with people having a contrasting technological background to its own. Through this experience the engineering graduates emerged with a greater sense of responsibility with the society and a better understanding of what means to be an engineer. Participation in the Extension Project also brought up several opportunities of professional recognition by the technicians and the visual impaired themselves, which stimulated the students do achieve better performance in the course.

scholarly journals Differences of endogenous polyamines and putative genes associated with paraquat resistance in goosegrass (Eleusine indica L.)

2019 ◽  
Author(s):  
Qiyu Luo ◽  
Jiping Wei ◽  
Zhaoxia Dong ◽  
Xuefeng Shen ◽  
Yong Chen
Keyword(s):  
Resistance Mechanism ◽  
Transcript Level ◽  
Vital Role ◽  
Transport Systems ◽  
Polyamine Metabolism ◽  
Eleusine Indica ◽  
Significant Difference ◽  
Paraquat Resistance ◽  
Polyamine Content ◽  
High Level

AbstractBackgroundParaquat is one of the most effective herbicides used to control weeds in agricultural management, while the pernicious weed goosegrass (Eleusine indica) has evolved resistance to herbicides, including paraquat. Polyamines provide high-level paraquat resistance in many plants. In the present study, we selected three polyamines, namely, putrescine, spermidine, and spermine, as putative genes to investigate their correlation with paraquat resistance by using paraquat-resistant (R) and paraquat-susceptible (S) goosegrass populations.ResultsThere was no significant difference in the putrescine nor spermine content between the R and S biotypes. However, 30 and 90 min after paraquat treatment, the spermidine concentration was 346.14-fold and 421.04-fold (P < 0.001) higher in the R biotype than in the S biotype, but the spermidine concentration was drastically reduced to a marginal level after 90 min. Since the transcript level of PqE was low while the spermidine concentration showed a transient increase, the PqE gene was likely involved in the synthesis of the paraquat resistance mechanism, regulation of polyamine content, and synthesis of spermidine and spermine. PqTS1, PqTS2, and PqTS3 encode transporter proteins involved in the regulation of paraquat concentration but showed different transcription patterns with synchronous changes in polyamine content.ConclusionEndogenous polyamines (especially spermidine) play a vital role in paraquat resistance in goosegrass. PqE, PqTS1, PqTS2, and PqTS3 were speculated on the relationship between polyamine metabolism and paraquat resistance. To validate the roles of PqE, PqTS1, PqTS2, and PqTS3 in polyamine transport systems, further research is needed.

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