Introduction We have shown previously that C-labeled bicarbonate (HCO3 ) can be hyperpolarized using Dynamic Nuclear Polarisation (DNP) and that when this is injected in vivo, the enzyme carbonic anhydrase (CA) rapidly interconverts this with carbon dioxide (CO2) [1]. Furthermore, we have also shown that selective saturation of the CO2 signal in vivo will decrease the H CO3 signal in the presen...

Due to the low CO2 concentration in seawater, macroalgae including Saccharina japonica have developed mechanisms for using the abundant external pool of HCO3 − as an exogenous inorganic carbon (Ci) source. Otherwise, the high photosynthetic efficiency of some macroalgae indicates that they might possess CO2 concentrating mechanisms (CCMs) to elevate CO2 concentration intracellularly around the ...

To predict effects of climate change on phytoplankton, it is crucial to understand how their mechanisms for carbon acquisition respond to environmental conditions. Aiming to shed light on the responses of extra- and intracellular inorganic C (Ci) fluxes, the cyanobacterium Trichodesmium erythraeum IMS101 was grown with different nitrogen sources (N2 vs NO3 (-)) and pCO2 levels (380 vs 1400 µatm...

Many microalgae induce an extracellular carbonic anhydrase (eCA), associated with the cell surface, at low carbon dioxide (CO2) concentrations. This enzyme is thought to aid inorganic carbon uptake by generating CO2 at the cell surface, but alternative roles have been proposed. We developed a new approach to quantify eCA activity in which a reaction-diffusion model is fit to data on (18)O remov...

Cyanobacteria probably exhibit the widest range of diversity in growth habitats of all photosynthetic organisms. They are found in cold and hot, alkaline and acidic, marine, freshwater, saline, terrestrial, and symbiotic environments. In addition to this, they originated on earth at least 2.5 billion years ago and have evolved through periods of dramatic O2 increases, CO2 declines, and temperat...

Coccolithophores play a crucial role in the marine carbon cycle and thus it is interesting to know how they will respond to climate change. After several decades of research the interplay between intracellular processes and the marine carbonate system is still not well understood. On the basis of experimental findings given in literature, a numerical cell model is developed that describes inorg...

Recent studies suggest that projected rises of aquatic CO2 levels cause acid-base regulatory responses in fishes that lead to altered GABAergic neurotransmission and disrupted behaviour, threatening fitness and population survival. It is thought that changes in Cl(-) and HCO3 (-) gradients across neural membranes interfere with the function of GABA-gated anion channels (GABAA receptors). So far...

B romide (Br) causes positive interference with all clinical laboratory methods for the detenmination of serum Cl (1 .2). Interference with Cl measurement is much greater with ion-selective electrode (ISE) technology (1 .3) than with coubometry (1 -4). We recently described a patient ingesting therapeutic amounts of pynidostigmine Br (MestInon1 , containing 1 8.4 mg of Br [30.6%j per 60-mg tabl...

Soluble adenylyl cyclase (sAC) is a source of the second messenger cyclic adenosine 3', 5' monophosphate (cAMP). sAC is directly regulated by bicarbonate (HCO(-) 3) ions. In living cells, HCO(-) 3 ions are in nearly instantaneous equilibrium with carbon dioxide (CO2) and pH due to the ubiquitous presence of carbonic anhydrases. Numerous biological processes are regulated by CO2, HCO(-) 3, and/o...

We investigated the pH of interlamellar water of trout (Salmo gairdneri) by following changes in the downstream pH of expired water using a stopped-flow method. As water flowed over the gills of control fish, there was a significant decrease in water pH. Acetazolamide added to the water increased the CO2 disequilibrium, while carbonic anhydrase (CA) eliminated the CO2 disequilibrium relative to...