enzyme 98janb 28 January 1998 to 13 February 1998 Ectoenzyme activity: a-glucosidase, b-glucosidase, alkaline phosphatase, leucine aminopepetidase. Different depths were sampled at each station. Depth profiles were usually constructed, although surface samples only were taken at several stations. See event log for this cruise and the enzyme data set. The number of stations sampled per day varied. Measurement of the potential activities of four ectoenzymes at different depths throughout the Palmer LTER grid. Samples for determination of potential a- and b-glucosidase and leucine aminopeptidase activities were processed as described by Christian and Karl (1995) after Hoppe (1983) and Somville and Billen (1983) using fluorescent substrate analogs (4-MUF and LLBN) applied at previously determined saturating concentrations. Briefly, a- and b-glucosidase and alkaline phosphatase activities were calculated from the fluorescences of triplicate 6 ml samples from each depth with a fourth, time zero control sample denatured immediately by addition of 100 ul of saturated mercuric chloride solution (final concentration, 4 mM). Fluorescent substrate analogs (200 ul) 4-methylumbelliferyl-a-D- glucosidase (MUAG), 4-methylumbelliferyl-b-D-glucosidase (MUBG) or 4-methylumbelliferyl phosphate were applied at saturating concentrations to the respective vials. Controls were frozen immediately (-20 C). Leucine aminopeptidase activities were calculated from the fluorescences of duplicate 6 ml samples in sterile polypropylene centrifuge tubes with L-leucine b-naphthylamide at saturating concentration, again with mercuric chloride denatured controls frozen upon inoculation. After 24 hours dark incubation at surface seawater temperature in flow through incubators, 100 ul of saturated mercuric chloride solution were added to each sample. Denatured samples were immediately frozen. Sample fluorescences were determined in a Perkin-Elmer LS-5 or LS-5B spectrofluorometer against a 4- methylumbelliferone standard at lambda(ex) = 360 nm and lambda(em) = 448 nm, or a b-naphthylamine standard at lambda(ex) = 338 nm and lambda(em) = 407 nm. Water samples collected from Go-Flo opened at depths determined during down-cast (on the basis of light levels). Samples collected into dedicated, opaque PTFE bottles. Subsamples inoculated with substrate analogs are incubated in scintillation vials (glucosidases, alkaline phosphatase) or PP centrifuge tubes (leucine aminopeptidase) in flow through incubators at in situ temperature (in darkness). Preliminary results: Glucosidase activities showed little, if any, consistent pattern with depth. b-glucosidase activity frequently below detection limit (1 pmol/L/hr). Leucine aminopeptidase (LAPase) tended to peak at the surface and show greatest potential activity reductions around 50 m, or 13% light level. The activity of each enzyme increased along the 200. line, from the open sea towards Marguerite Bay, and each showed peak activities in surface samples at station 200.-060. a-glucosidase, b-glucosidase, alkaline phosphatase, leucine aminopeptidase, LLBN, ectoenzyme /home/data3/data/98janb/enzyme lmg9801.enz David M. Karl Dr. Stuart P. Donachie, Dr. J. Christian Stuart Donachie, University of Hawaii Stuart Donachie Stuart Donachie Stuart Donachie Stuart Donachie Lance Fujieki, University of Hawaii 6/1/98 Christian JR and DM Karl (1995) measuring bacterial ectoenzyme activities in marine waters using mercuric chloride as a preservative and a control. Mar Ecol Prog Ser 123:217-224 Hoppe HG (1983) Significance of exoenzymatic activities in the ecology of brackish water: measurements by means of methylumbelliferyl substrates. Mar Ecol Prog Ser 11:299-308 Somville M and G Billen (1983) A method for determining exoproteolytic activity in natural waters. Limnol Oceanogr 28:190-193