The effects of aflatoxin B1, citrinin, and ochratoxin A on amino acid uptake and incorporation by cucumber

1972 ◽  
Vol 50 (12) ◽  
pp. 2659-2664 ◽  
Author(s):  
Audrey G. White ◽  
Bryan Truelove
Keyword(s):  
Amino Acid ◽  
Ochratoxin A ◽  
Time Course ◽  
Amino Acid Uptake ◽  
Acid Uptake ◽  
Cucumber Cotyledon ◽  
Leucine Uptake ◽  
Pretreatment Time ◽  
Aflatoxin B ◽  
Subsequent Incorporation

Both aflatoxin B1 and citrinin, in light and darkness, inhibited leucine uptake and its incorporation into protein by cucumber cotyledon disks. Aflatoxin was more inhibitory in the light and both toxins showed increased inhibition with increasing concentration. At a concentration of 50 μg/ml, citrinin was more inhibitory to amino acid absorption than aflatoxin. Time-course studies showed that a pretreatment time of at least 2 h was necessary with aflatoxin to affect the subsequent incorporation of leucine; citrinin, on the other hand, was inhibitory when it was supplied together with the 14C-leucine. In darkness, ochratoxin A at 10, 50, and 100 μg/ml enhanced leucine uptake but did not affect its incorporation into protein.

The effects of aflatoxin B1 on protein synthesis by cucumber cotyledon discs

1970 ◽  
Vol 48 (3) ◽  
pp. 485-491 ◽  
Author(s):  
B. Truelove ◽  
D. E. Davis ◽  
Olivia C. Thompson
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Time Course ◽  
Actinomycin D ◽  
Amino Acid Uptake ◽  
Plant Tissues ◽  
Acid Uptake ◽  
Cucumber Cotyledon ◽  
Low Concentrations ◽  
Aflatoxin Concentration

The effects of aflatoxin on amino acid uptake and incorporation into protein by discs of cucumber cotyledon tissue showed that incubation for relatively short periods with low concentrations of aflatoxin reduced the amount of 14C-leucine absorbed without affecting incorporation into protein; increasing incubation time or increasing aflatoxin concentration inhibited the incorporation of absorbed leucine into protein. The effects of aflatoxin and actinomycin D on leucine absorption and incorporation were compared in a time course study.The data are discussed in relation to the possible mode of action of aflatoxin in plant tissues.

Myocardial amino acid transport by canine sarcolemma vesicles

1987 ◽  
Vol 252 (6) ◽  
pp. H1070-H1076
Author(s):  
L. H. Young ◽  
B. L. Zaret ◽  
E. J. Barrett
Keyword(s):  
Amino Acid ◽  
Sarcoplasmic Reticulum ◽  
Membrane Vesicles ◽  
Amino Acid Uptake ◽  
Ventricular Myocardium ◽  
Transport Systems ◽  
Acid Uptake ◽  
Leucine Uptake ◽  
Alanine Transport ◽  
Canine Ventricular Myocardium

The transport of L-alanine and L-leucine into membrane vesicles isolated from mature canine ventricular myocardium was studied. Transport was assessed in purified sarcolemma and in vesicles differentially enriched either for sarcolemma or sarcoplasmic reticulum to further localize these transport systems. An imposed inward gradient of a NaNO3 stimulated uptake of L-alanine but not L-leucine by these vesicles. Amino acid uptake by these vesicles occurred into an osmotically active space. The stimulatory effect of Na+ on alanine transport was most striking in the purified sarcolemma vesicles, where Na+-stimulated alanine flux was 45 +/- 14 pmol X mg-1 X min-1. Furthermore, Na+-dependent alanine transport activity appeared to copurify with Na+-K+-ATPase activity, which served as a marker for sarcolemma membrane when these activities were compared in the three different membrane preparations. Leucine transport by sarcolemma was not altered by an imposed Na+ gradient. However, leucine uptake was a saturable function of extravesicular leucine and was inhibited by valine. In contrast, in sarcoplasmic reticulum membrane vesicles leucine uptake increased proportionately with increasing media leucine and was unaffected by valine. Our results demonstrate the feasibility of directly studying the transport of naturally occurring amino acids in membrane vesicles from mammalian heart, and the presence of Na+-dependent alanine transport system and a Na+-independent leucine transporter in the sarcolemma but not in sarcoplasmic reticulum of canine ventricular myocardium.

INFLUENCE OF PHYSIOLOGICAL STATE AND OF FASTING ON AMINO ACID UPTAKE BY INTESTINAL TISSUE OF CATTLE

1984 ◽  
Vol 64 (5) ◽  
pp. 314-315 ◽  
Author(s):  
J. K. HA ◽  
J. J. KENNELLY
Keyword(s):  
Amino Acid ◽  
Key Words ◽  
Physiological State ◽  
Amino Acid Uptake ◽  
Acid Uptake ◽  
Early Lactation ◽  
Mucosal Tissue ◽  
Intestinal Tissue ◽  
Leucine Uptake ◽  
Key Words Amino Acid

Leucine and lysine uptake by duodenal mucosal tissue of cows were increased during early lactation compared to the final 2 wk of gestation. The uptake of leucine appeared to be higher than that of lysine at both physiological stages. Fasting steers for 5 days did not significantly affect leucine uptake. Key words: Amino acid uptake, intestinal tissue, cattle

Accumulation of L-phenylalanine by segments of small intestine

1961 ◽  
Vol 200 (3) ◽  
pp. 505-507 ◽  
Author(s):  
A. H. Samiy ◽  
Richard P. Spencer
Keyword(s):  
Small Intestine ◽  
Amino Acid ◽  
Time Course ◽  
Amino Acid Uptake ◽  
Acid Uptake ◽  
Outward Diffusion ◽  
Initial Event ◽  
Equilibrium Data ◽  
Site Dependence

Segments of hamster small intestine accumulate l-phenylalanine from an in vitro solution without degradation of the amino acid. Uptake by the segments equilibrates in about 20 minutes, while transport of the amino acid across intestinal sacs requires nearly 1 hour. This suggests that the initial event preceding transintestinal transport is cellular uptake of l-phenylalanine. Concentration of the amino acid in the wall of intestinal sacs during l-phenylalanine transport was equal to or greater than that in the serosal fluid. Hence it is possible that intramural accumulation is the active process and outward diffusion from wall to serosa is the passive event. Dependence of segmental uptake of l-phenylalanine on external concentration, and its increased magnitude in midintestinal segments, resembles the process occurring in intestinal sacs. On the basis of the time course of events, concentration within the wall, and concentration and site dependence, it is proposed that intestinal uptake of l-phenylalanine is the initial and essential event in its transport. For l-phenylalanine uptake, the KM calculated from initial rate data was identical to that found from equilibrium data. Usefulness of intestinal segment uptake in determining initial rates and other parameters is pointed out.

scholarly journals Molecular Imaging of Brain Tumor-Associated Epilepsy

Diagnostics ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1049
Author(s):  
Csaba Juhász ◽  
Sandeep Mittal
Keyword(s):  
Brain Tumor ◽  
Amino Acid ◽  
Brain Tumors ◽  
Treatment Strategies ◽  
Amino Acid Uptake ◽  
Seizure Outcome ◽  
Acid Uptake ◽  
Positron Emission ◽  
Oncology Practice ◽  
Glioneuronal Tumors

Epilepsy is a common clinical manifestation and a source of significant morbidity in patients with brain tumors. Neuroimaging has a pivotal role in neuro-oncology practice, including tumor detection, differentiation, grading, treatment guidance, and posttreatment monitoring. In this review, we highlight studies demonstrating that imaging can also provide information about brain tumor-associated epileptogenicity and assist delineation of the peritumoral epileptic cortex to optimize postsurgical seizure outcome. Most studies focused on gliomas and glioneuronal tumors where positron emission tomography (PET) and advanced magnetic resonance imaging (MRI) techniques can detect metabolic and biochemical changes associated with altered amino acid transport and metabolism, neuroinflammation, and neurotransmitter abnormalities in and around epileptogenic tumors. PET imaging of amino acid uptake and metabolism as well as activated microglia can detect interictal or peri-ictal cortical increased uptake (as compared to non-epileptic cortex) associated with tumor-associated epilepsy. Metabolic tumor volumes may predict seizure outcome based on objective treatment response during glioma chemotherapy. Advanced MRI, especially glutamate imaging, can detect neurotransmitter changes around epileptogenic brain tumors. Recently, developed PET radiotracers targeting specific glutamate receptor types may also identify therapeutic targets for pharmacologic seizure control. Further studies with advanced multimodal imaging approaches may facilitate development of precision treatment strategies to control brain tumor-associated epilepsy.

scholarly journals Polyribonucleotide Synthesis and Bacterial Amino Acid Uptake: the Work of Leon A. Heppel

2007 ◽  
Vol 282 (18) ◽  
pp. e13-e15
Author(s):  
Nicole Kresge ◽  
Robert D. Simoni ◽  
Robert L. Hill
Keyword(s):  
Amino Acid ◽  
Amino Acid Uptake ◽  
Acid Uptake

scholarly journals Amino Acid Transporters on the Guard of Cell Genome and Epigenome

Cancers ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 125
Author(s):  
Uğur Kahya ◽  
Ayşe Sedef Köseer ◽  
Anna Dubrovska
Keyword(s):  
Amino Acid ◽  
Cancer Metabolism ◽  
Tumor Imaging ◽  
Redox Homeostasis ◽  
Amino Acid Uptake ◽  
Metabolic Reprogramming ◽  
Tumor Evolution ◽  
Amino Acid Transporters ◽  
Acid Uptake ◽  
Growth And Survival

Tumorigenesis is driven by metabolic reprogramming. Oncogenic mutations and epigenetic alterations that cause metabolic rewiring may also upregulate the reactive oxygen species (ROS). Precise regulation of the intracellular ROS levels is critical for tumor cell growth and survival. High ROS production leads to the damage of vital macromolecules, such as DNA, proteins, and lipids, causing genomic instability and further tumor evolution. One of the hallmarks of cancer metabolism is deregulated amino acid uptake. In fast-growing tumors, amino acids are not only the source of energy and building intermediates but also critical regulators of redox homeostasis. Amino acid uptake regulates the intracellular glutathione (GSH) levels, endoplasmic reticulum stress, unfolded protein response signaling, mTOR-mediated antioxidant defense, and epigenetic adaptations of tumor cells to oxidative stress. This review summarizes the role of amino acid transporters as the defender of tumor antioxidant system and genome integrity and discusses them as promising therapeutic targets and tumor imaging tools.

scholarly journals Studies on Aromatic Amino Acid Uptake by Rat Brain in Vivo

1962 ◽  
Vol 237 (3) ◽  
pp. 803-806
Author(s):  
Gordon Guroff ◽  
Sidney Udenfriend
Keyword(s):  
Amino Acid ◽  
Rat Brain ◽  
Aromatic Amino Acid ◽  
Amino Acid Uptake ◽  
Acid Uptake
Sign in / Sign up

Export Citation Format

Share Document