METHYLAMINE UPTAKE IN THE GREEN ALGA CHLORELLA PYRENOIDOSA¹

Abstract

Methylamine uptake in nitrogen‐starved Chlorella pyrenoidosa Beij. follows Michaelis‐Menten kinetics: maximum uptake is about 1.6 nmol μl−1· cells · min−1, half‐saturation occurs at 4 μM methylamine, and the slope in the range where uptake is proportional to concentration is 0.4 nmol μl−1· min−1·μM−1. In cells grown in the presence of a non‐limiting nitrogen concentration, methylamine uptake is directly proportional to concentration up to at least 0.5 mM, and the slope is 1/500 that for starved cells. Similar uptake kinetics have been reported for Penicillium chrysogenum and attributed to an inducible “ammonium permease.” Apparently, a similar permease occurs in algae.

An evaluation of the metabolism of sestonic and epilithic communities in running waters using an improved chamber technique

“…Ammonia uptake was measured using '*Cmetbylamine bydrocbloride (1.81 CiBq mmol"', New England Nuclear), Its suitability as an ammonium analogue has been demonstrated (Wheeler, 1979(Wheeler, , 1980Pelley & Bannister, 1979). Radioisotope (0.37 GBq) was added to the chamber and after 20 s, a 1 ml aliquot was taken from the chamber with a syringe to determine the total activity added.…”

Suppression of ammonium uptake by nitrogen supply and its relief during nitrogen limitation

“…Feedback inhibition of NHf uptake by nitrogenous effectors (Kleiner 1985) has been implicated in Lemna (Ullrich et al 1984). algae (Pelley and Bannister 1979, MacFarlane and Smith 1982, Wright and Syrett 1983, Thomas and Harrison 1985 and yeast (Wiame et al 1085). In the latter, glutamine appears to be the negative effector, and both repression o f synthesis and inhibition of activity of the NHf influx system are involved (Cook and Anthony 1978a.b.…”

Seasonal pattern of ammonium (methylamine) uptake by phytoplankton in an oligotrophic lake

“…The highest uptake rates of MeA during our study when inorganic nitrogen levels were lowest agrees with the enhanced ammonium and MeA uptake by cultured green algae, diatoms, and natural populations under nitrogen deficient conditions (Myers, 1951;Eppley & Renger, 1974;Healey & Hendzel, 1979;Pelley & Banister, 1979;Vincent, 1981;Hellebust et al, 1985;Suttle & Harrison, 1988;Cochlan & Harrison, 1991). The opposite relationship has been reported, however, for blue-green algae (Vincent, 1979).…”