Notes: Germination and growth of Bacillus cereus spores from emetic and diarrheal strains were measured in Trypticase soy broth (TSB) and in autoclaved rice/beef extract from 5°– 55°C. Growth for some strains occurred from 15°– 50°C, and little difference was noted between responses of diarrheal and emetic types or between media, except a higher maximum population was achieved in rice. Germination was more extensive in rice than in TSB at 〈15°C and was generally more extensive for diarrheal strains in either medium.

Notes: Survival, spore germination, and growth of emetic and diarrheal type strains of Bacillus cereus were evaluated in broth and rice media during heating and cooling. Samples were heated to 80°C (20C°/hr or 40C°/hr) or 90°C (ca. 900C°/hr), prior to cooling to 10°C (5C°/hr or 10C°/hr). Following heating to 80°C, growth occurred during 5C°/hr cooling. After heating to 90°C, inactivation of three strains occurred during cooling from 90 to 80°C and again from 50 to 40°C. Great variability was observed among the responses of the four strains. Emetic strains exhibited greater survival than diarrheal strains. Rice reduced low temperature inactivation, and did not favor emetic strains. Significant two and three way interactions existed among media, strains, heating and cooling rates.

Notes: Bacillus cereus has been implicated as the cause of both diarrheal and emetic forms of food-borne illness. Spores of eight strains of B. cereus, representing diairheal, emetic and atoxigenic origins, were examined for heat resistance and germination responses. No correlation was observed between heat resistance at 85° or 90°C and origin of the strain. Germination of spores in Trypticase soy broth at 30°C, measured by loss of heat resistance, was more extensive for diarrheal strains than for emetic strains. These data should be useful in evaluating potential hazards from B. cereus in foods.

Notes: Summary Acute administration of phencyclidine hydrochloride (PCP) resulted in a dose-responsive decrease in the conversion of3H-tryptophan to3H-serotonin (3H-5-HT) in rat forebrain. Subsequent experiments measured the effect of a subthreshold dose of PCP (4 mg/kg) daily for one, seven, or fourteen days on this index of 5-HT turnover. Although single administration again had no effect at this dose, repeated administration for seven days resulted in a 37% decrease in 5-HT turnover. However, after fourteen days of administration this index was not significantly different from saline controls. The possible significance of these findings are discussed in relation to reported alterations in PCP-induced behaviors observed with chronic administration.

Notes: Abstract In an attempt to evaluate ΣCO2 changes as an index of net ecosystem metabolism, ΣCO2 and dissolved organic carbon (DOC) by infrared (IR) analysis and O2 by the Winkler method were followed over 12 diel cycles in a salt marsh, a simulated estuarine ecosystem, and the mixed layer of the northwestern Caribbean Sea. Each ecosystem exhibited replicable diel cycles, net production during the photoperiod, and a significant inverse correlation between ΣCO2 and O2 changes. Daily rates of system production and respiration calculated from ΣCO2, however, exceeded those from O2 by 1.5 to 3.5 fold in nearshore waters and by 2 to 6 fold in the open ocean. Net total system apparent production based on O2 and ΣCO2, respectively, were 2 345 and 3 604 mg C m-3d-1 for the salt marsh, 348 and 625 mg C m-3d-1 for the estuarine ecosystem, and 53 and 306 mg C m-3d-1 for the oceanic ecosystem, both parameters exceeding 14C data in the literature for similar environments by one to two orders of magnitude. The IR ΣCO2 productivity estimates are compatible with the diel cycles in DOC. In the marsh and Caribbean Sea, maxinium DOC concentrations were usually observed in the evening following a gradual accumulation during the photoperiod, while minimal values occurred in the early morning. In all ecosystems the average net release of DOC lagged CO2 uptake and O2 production and represented 22.7 and 43.3% of the carbon fixed as estimated from CO2 uptake and O2 production, respectively. If the consistently higher ΣCO2 measurements are not a systematic error nor due to atmospheric diffusion, then diel variation in O2 and CO2 may not always be quantitatively coupled due in part to habitat-dependent factors such as the nonphotosynthetic incorporation of CO2 and chemosynthetic removal of O2.

Notes: Abstract Dissolved total carbohydrate (TCHO), polysaccharide (PCHO), monosaccharide (MCHO) and organic carbon (DOC) were determined at 3-h intervals over 5 diel cycles in the mixed layer of the northwestern Caribbean Sea while following a drogued buoy. These data have been compared to populations of phototrophic (PNAN) and heterotrophic (HNAN) nanoplankton (2–20 μm diameter) and heterotrophic bacteria (HBAC) (0.2–2.0 μm diameter) estimated by epifluorescence counts, as well as to ΣCO2, phosphate, chlorophyll a and phaeopigment data determined simultaneously. Two different types of apparent diel dissolved carbohydrate (CHO) patterns were found. On 3 d when no sustained net ΣCO2 uptake was evident, TCHO and PCHO generally declined during the afternoon and early evening while MCHO tended to increase. On two other days when apparent sustained ΣCO2 uptake occurred during the day, there were large evening TCHO and PCHO peaks with constant or declining MCHO levels. These accumulations probably resulted from the release of recently produced PCHO from phototrophs. As was found earlier in the Sargasso Sea, PNAN populations were inversely related to PCHO concentrations. The sample to sample fluctuations of PNAN also were inversely related to the apparent rates of change of TCHO and PCHO, possibly due to an inverse relation between the rates of PNAN cell division and CHO excretion. Fluctuations in HBAC populations were inversely correlated with PCHO dynamics and directly related to MCHO variations, possibly due to extracellular hydrolysis of PCHO to MCHO during periods of rapid bacterial growth as well as to net heterotrophic PCHO uptake. A direct relationship between HNAN and TCHO fluctuations suggests the importance of HNAN excretion in the release of dissolved organics. The combined PNAN and HBAC fluctuations accounted for a more significant fraction of the variance in the apparent rates of change of PCHO than did any single population parameter indicating that intimate interactions between the microbial plankton groups are important in the in-situ regulation of CHO dynamics. Total system net TCHO release and uptake rates for 5 d averaged 56 and 53 μg C l-1 d-1 respectively, assuming that the observed fluctuations resulted from temporal planktonic processes in homogeneous water masses. While the data contain indications that this was the case, this assumption is not definitive.

Notes: Abstract The concentrations of total dissolved carbohydrate (TCHO), monosaccharide (MCHO) and polysaccharide (PCHO) were followed over a total of ten diel cycles in a salt marsh and a 13 m3 seawater tank simulating an estuarine ecosystem. Their patterns are compared to those for total dissolved organic carbon (DOC), ΣCO2, pH, O2, chlorophyll a, phaeopigments and solar radiation. During 5 of the 6 marsh studies, PCHO underwent periods of sustained accumulation starting in the late morning or early afternoon and continuing into the early evening. These periods possibly represent release of recently synthesized PCHO from phototrophs. similar patterns were not found in the tank although direct associations between TCHO and phaeopigment dynamics suggest that zooplankton excretion was an important source of dissolved carbohydrate. The numbers of planktonic bacteria determined in one tank study increased rapidly during a late morning PCHO pulse and varied inversely with PCHO throughout the afternoon and evening, indicating that they were able to respond rapidly and control natural substrate concentrations on a time scale of a few hours. MCHO fluctuated to a much lesser extent than PCHO at both locations with levels possibly maintained near the bacterial uptake threshold or in a closely regulated steady state. TCHO concentration changes over 2-to 3-h sampling intervals suggest very rapid net system release and uptake with summer rates frequently exceeding 30 μg C l-1h-1 in the marsh and 20 μg C l-1 h-1 in the tank.

Notes: Abstract Six diel TCO2 cycles determined by infrared (IR) photometry from five drift stations occupied between 24 February and 16 March 1979 in the mixed layer of the northwestern Caribbean Sea are examined. Comparison of TCO2 variation with coincident salinity and O2 variation demonstrated that TCO2 often co-varied with these independently measured variables. During five diel cycles TCO2 variation was characterized by nocturnal production and diurnal consumption. The inverse, diurnal production of CO2, occurred downstream from Misteriosa Bank, whose corals apparently contributed to a water mass having a twofold increase of POC and a sixfold larger population of heterotrophic nanoplankters. For the five diel studies carried out in waters with balanced or nearly blanced heterotrophic and phototrophic components of the nanoplankton, CO2 consumption at constant salinity always occurred between 06.00 and 09.00 hrs. Net uptake often continued through 15.00 hrs, but not always in the absence of significant salinity changes. At constant salinity net O2 evolution never exceeded 0.5 μmol l-1 h-1 while net CO2 uptake consistently averaged 3 μmol l-1 h-1 for an apparent net production of 36 mg C m-3 h-1, which greatly exceeds the O2 changes and open ocean 14C estimates from the literature. Diurnal consumption was apparently balanced by nocturnal production of CO2 so that no significant net daily change in TCO2 was observed. Departures from theoretical PQ and RQ and the possibility of nocturnal variations in formaldehyde and carbonate alkalinity imply that chemotrophs, both methane producers and methane oxidizers, play a significant role in CO2 cycling. This could be through the metabolism of the nonconservative gases CH4, CO, and H2, and a link between chemotrophy and phototrophy through these gases is hypothesized. These open system measurements were subject to diffusion and documentable patchiness, but temporal TCO2 changes appear to indicate the net direction of microbiological activity and join a growing body of literature showing dynamic variation in CO2 and O2 that exceeds estimates by 14C bottle assays of carbon fixation.

Notes: Abstract The release via exudation of dissolved organic carbon by Ascophyllum nodosum (L.) Le Jol. was investigated under laboratory conditions. In contrast to results previously reported by Sieburth (1969), continuous release of organic matter was found with only 1 specimen out of 21 tested either in stagnant sea water or in sea water flowing through the system. The holdfast of the plants was found to release relatively large amounts of organic material; however, this release lasted only for short periods, and was most probably due to damage caused by removing the plants from their substrate. The possible reasons for the failure to detect exudation are discussed. With Fucus vesiculosus L., no reliable results could be obtained, most probably due to particulate matter sloughing off the plants during the washings and during the experiments under conditions of photosynthesis.

Notes: Abstract The release of dissolved organic carbon (DOC) by Ascophyllum nodosum (L.) Le Jol. and Fucus vesiculusus L. during rehydration was investigated after desiccation under experimental conditions. During 30 min of rehydration of plants which had lost up to 70% of their water, A. nodosum released about 2 to 10 mg C/100 g dry weight, while F. vesiculosus released 10 to 50 times more. When dried to water losses exceeding 70%, plants of both species yielded similar amounts of DOC, approximating 2 g C/100 g dry weight. Considerable variance in the amounts of DOC released by individual plant of both species was observed over the whole range of water losses tested. Among the DOC released, the portion of carbohydrate-C was O to 5% with A. nodosum but 2 to 47% with F. vesiculosus. This difference was most pronounced when less than 100 mg C/100 g dry weight were released. A. nodosum regained a smaller percentage of its original weight than F. vesiculosus after 30 min of rehydration when more than 30% of fresh weight were lost during desiccation. Curves were obtained which enable the estimation of water losses in naturally desiccated specimens within 30 min.