we have simulated the carrier concentration and temporal response characteristics of a back-gated metal- semiconductor-metal (bg-msm) photodetector in one dimension as a function of optical pulse position on the active region in an equilibrium condition (without bias voltage to the photodetector). we have adopted a nonlinear ambipolar transport model to simulate the behavior of photo-generated ...

Thyroid hormones (TH) are essential for the development of the human brain, growth and cellular metabolism. Investigation of TH transporters became one of the emerging fields in thyroid research after the discovery of inactivating mutations in the Monocarboxylate transporter 8 (MCT8), which was found to be highly specific for TH transport. However, additional transmembrane transporters are also...

An investigation was made of azaserine entry into cells of a sensitive and resistant line of the plasma-cell neoplasm 70429. Transport experiments determined (a) the initial velocity of concentrative uptake in the first 1 or 2 minutes of exposure to the compound, (6) the total kinetics of uptake over 30-minute to 90-minute periods, and (c) the dependence of steady-state uptake on the extracellu...

N-ethylmaleimide (NEM) inhibits the transport of phosphate in mitochondria but is without effect on permeation of other metabolities. In spite of its specificity for inhibition of phosphate transport, NEM reacts in an unspecific manner with inner membrane proteins in general. Treatment of mitochondria with [3H]NEM just sufficient to produce inhibition of phosphate transport results in labeling ...

Fluorescence and electrophysiological methods were used to determine the effects of intracellular pH (pHi) on cellular NH4+/K+ transport pathways in the renal medullary thick ascending limb of Henle (MTAL) from CD1 mice. Studies were performed in suspensions of MTAL tubules (S-MTAL) and in isolated, perfused MTAL segments (IP-MTAL). Steady-state pHi measured using 2,7-biscarboxyethyl-5(6)-carbo...

Semi-intact cells, a cell population in which the plasma membrane is perforated to expose intact intracellular organelles (Beckers, C. J. M., Keller, D. S., and Balch, W. E. (1987) Cell 50, 523-534), efficiently reconstitute vesicular trafficking of protein from the endoplasmic reticulum (ER) to the cis Golgi compartment. We now extend these studies to biochemically dissect transport of protein...

The small GTPase ADP-ribosylation factor (ARF) is absolutely required for coatomer vesicle formation on Golgi membranes but not for anterograde transport to the medial-Golgi in a mammalian in vitro transport system. This might indicate that the in vivo mechanism of intra-Golgi transport is not faithfully reproduced in vitro, or that intra-Golgi transport occurs by a nonvesicular mechanism. As o...

Both Cs(+) and NH(4)(+) alter neuronal Cl(-) homeostasis, yet the mechanisms have not been clearly elucidated. We hypothesized that these two cations altered the operation of the neuronal K(+)-Cl(-) cotransporter (KCC2). Using exogenously expressed KCC2 protein, we first examined the interaction of cations at the transport site of KCC2 by monitoring furosemide-sensitive (86)Rb(+) influx as a fu...

In osmoregulating teleost fish, urea is a minor nitrogen excretory product, whereas in osmoconforming marine elasmobranchs it serves as the major tissue organic solute and is retained at relatively high concentrations ( approximately 400 mmol/l). We tested the hypothesis that urea transport across liver mitochondria is carrier mediated in both teleost and elasmobranch fishes. Intact liver mitoc...

Ion transport is the major determining factor of salinity tolerance in plants. A simple scheme of a plant cell with ion fluxes provides basic understanding of ion transport and the corresponding changes of ion concentrations under salinity. The review describes in detail basic principles of ion transport for a plant cell, introduces set of transporters essential for sodium and potassium uptake ...