Preservation of enzymic activity in marine plankton by low-temperature freezing

Ahmed, S. I.; Kenner, R. A.; King, Frederick D.

doi:10.1016/0304-4203(76)90002-5

Cited by 44 publications

(16 citation statements)

References 5 publications

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“…Ahmed et al (1976) found that ETS activity and GDH activity in whole cells of marine phytoplankton could be preserved without loss for up to 1 yr in liquid nitrogen, but Clayton (1986) reported losses of activity in S. costatum NR of up to 40% immediately after freezing in liquid nitrogen. Such losses were not found in this study, suggesting that in field situations samples could be frozen in liquid nitrogen for later analyses.…”

Section: Discussionmentioning

confidence: 99%

Nitrate reductase activity quantitatively predicts the rate of nitrate incorporation under steady state light limitation: A revised assay and characterization of the enzyme in three species of marine phytoplankton

Berges

Harrison

1995

Limnology & Oceanography

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The enzyme nitrate reductase (NR) has been proposed as an index of nitrate incorporation rates in marine phytoplankton, but it has proven difficult to interpret NR measurements in field settings because many previous NR assays have been poorly optimized and NR activity in phytoplankton has been poorly characterized under steady state conditions. An NR assay was developed for the diatom Thalassiosira pseudonana using an extraction in phosphate buffer with Triton X-100, EDTA, dithiothreitol, polyvinyl pyrrolidone, and bovine serum albumin. NR activity in homogenates was stable for up to 1 h, but filtered samples could be stored for 96 h in liquid nitrogen without significant loss of activity. Addition of FAD to crude extracts of T. pseudonana had no effect, whereas the effect on desalted extracts or crude extracts from other species, varied from decreases in NR activity to over 250% increases. Half-saturation constants (K,) varied between species; high levels of NADH or nitrate were found to be inhibitory in some cases. These results indicate a wide diversity of forms of NR in marine phytoplankton.Under continuous, light-limited growth, NR activity was quantitatively related to calculated rates of nitrate incorporation (pN) in T. pseudonana, Skeletonema costatum, and three other diatom species examined. The relationship differed for 10 other species; NR activity was equal to bN in some cases, but higher or lower in others. In dinoflagellates, in particular, NR activity was highly correlated with pN, but accounted for ~20% of hN in Amphidinium carterae.The importance of nitrogen metabolism in general, and nitrate metabolism in particular, in the marine environment is based not only on the frequent identification of nitrogen as a nutrient limiting primary production, but also because of the important differences between the fate of production depending on whether newly available nitrogen (e.g. nitrate) or regenerated forms (e.g. ammonium) are used (Dugdale and Goering 1967;Platt et al. 1992). Thus, measurements of rates of nitrate incorporation (sensu Wheeler 1983, i.e. the combination of inorganic nitrogen into large macromolecules such as proteins and nucleic acids) by marine phytoplankton are critical to understanding rates of primary production and biogeochemical cycling in many areas of the oceans.Current methods of estimating rates of nitrate incorporation are based largely on incubation techniques with the stable isotope 15N as a tracer (Dugdale and Wilkerson 1986). It is appreciated that there are problems with this

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Section: Discussionmentioning

confidence: 99%

Nitrate reductase activity quantitatively predicts the rate of nitrate incorporation under steady state light limitation: A revised assay and characterization of the enzyme in three species of marine phytoplankton

Berges

Harrison

1995

Limnology & Oceanography

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“…Half of the frozen samples were then transferred to a conventional deep freeze (-15°C) and the other half stored in liquid nitrogen (-196°C Ahmed et al (1976).…”

Section: Methodsmentioning

confidence: 99%

Zooplankton respiration and its relation to plankton dynamics in two lakes of contrasting trophic state1

Devol¹

1979

Limnology & Oceanography

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The seasonal cycles of respiration of net zooplankton and microplankton were determined for euphotic zones of Lake Washington and Findlcy Lake. In Lake Washington net zooplankton respiration rates estimated from ETS activity ranged from 22.4 to 1,194 mg 0 * rnd2. d-l with the maximum occurring during the spring bloom. Net zooplankton respiration rates in Findlcy Lake ranged from 27 mg 0. mm2 * d-l under ice cover to a maximum of 205 mg 0 * rnp2 * d-l, which occurred well after the bloom. Respiration rates estimated from ETS activity agreed well with those estimated from zooplankton species abundance. Zooplankton community respiration never exceeded 60% of primary production in Lake Washington; however, in Findlcy Lake zooplankton community respiration rates exceeded primary production during the latter part of the ice-free growing season. Phosphorus regeneration rates calculated from zooplankton respiration appeared sufficient to supply most of the phytoplankton phosphorus reqtlirement during summer stratification in Lake Washington.

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“…Similar differences are reported for long-term storing. Ahmed et al (1976), Ikeda & Skjoldal (1980 and Ikeda & Hing Fay (1981) apparently recorded good results with freezing and storing their samples (of whole organisms) at -20°C, but others (with homogenized samples) did not (Packard 1971, BAmstedt 1980. Apparently many factors influence the ETS activity in the samples.…”

Section: Discussionmentioning

confidence: 99%

Respiratory electron transport system (ETS) activities in zooplankton and micronekton of the Indo-Pacific region

Schalk¹

1988

Mar. Ecol. Prog. Ser.

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ETS activities of natural zooplankton assemblages and some micronekton species from the eastern Banda Sea and western Arafura Sea (Indonesia) were measured during the SE and NW monsoons, when respectively rich upwehng and poor downwelling condtlons occur. Weight-specific ETS activities of the zooplankton community decreased with depth; 13 to 20 % of this decrease was related to temperature, and another 5 to 10 % to hlgher water contents of the deeper samples. Large geographical dfferences, but no seasonal differences, were detected within the area studled. About 65 % of the total zooplankton ETS activity in the upper 500 m was confined to the upper 100 m. Day/ night differences in ETS profiles were observed during the less fertile NW monsoon period, attributed to diel vertical migration of the zooplankton, and resulting in a 9 to 36 90 lower activity in the water column during daytime. Since no diel migration by the zooplankton was seen in the fertlle SE monsoon season, the abundance of food, or the necessity to conserve energy, seems a major factor in determining d e l vertical migration. Of the micronekton examined, shallow-living species and those performing d e l vertical migration showed higher weight-specific ETS activities than deeper living and non-migrating species. Myctophid fishes and carid crustaceans showed very high weight-specific activities; chauliodontids, gonostomatids, euphausids and sergestids moderate activities; and leptocephali, chdeiognains, saips, siphonophores and medusas low activities. None of the micronekton species investigated showed seasonal differences in ETS activity.

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Preservation of enzymic activity in marine plankton by low-temperature freezing

Cited by 44 publications

References 5 publications

Nitrate reductase activity quantitatively predicts the rate of nitrate incorporation under steady state light limitation: A revised assay and characterization of the enzyme in three species of marine phytoplankton

Nitrate reductase activity quantitatively predicts the rate of nitrate incorporation under steady state light limitation: A revised assay and characterization of the enzyme in three species of marine phytoplankton

Zooplankton respiration and its relation to plankton dynamics in two lakes of contrasting trophic state1

Respiratory electron transport system (ETS) activities in zooplankton and micronekton of the Indo-Pacific region

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