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11.
Distinction between light-mediated and light-independent variations in phytoplankton production rates 总被引:1,自引:1,他引:0
Max M. Tilzer 《Hydrobiologia》1989,173(2):135-140
An array of factors simultaneously controls phytoplankton photosynthesis and hence the primary production process. Because their relative importance shifts both with depth and with season, the significance of individual factors cannot be resolved by in situ incubations, even if all relevant environmental and biotic variables are measured.Here a procedure is described by which in addition to in situ measurements, photosynthesis is simultaneously assessed in identical subsamples under constant temperature (10 °C) and light (0.66 mol m–2 h–1 PAR conditions, in vitro). By calculating photosynthesis per unit of chlorophyll, effects of shifting biomass on photosynthesis can be eliminated but seasonal variations of light-saturated photosynthesis generated by temperature, and vertical changes of light-requirements (e.g. by light-shade adaptation) remain obscure. Quotients of in situ photosynthetic rates divided by in vitro rates allow the quantification of light-mediated changes. Provided that photosynthesis measured in vitro is light-saturated, quotients in situ: in vitro rates should never exceed unity. They are a measure for the degree of light-limitation. In vitro rates normalized to chlorophyll give information on temporal changes caused by variations in photosynthetic capacity. In Lake Constance, mean cell size appears to control light-saturated assimilation numbers. 相似文献
12.
Max Lechner Herbert Märkl Friedrich Götz 《Applied microbiology and biotechnology》1988,28(4-5):345-349
Summary In a newly constructed one-vessel dialysis fermentor, a strain of Staphylococcus carnosus TM300 carrying the lipase secretion plasmid pLipPS1 was used to investigate exoenzyme and biomass production. The bacterial culture grows in an inner compartment of 21 volume, separated from a 101 nutrient broth compartment by a conventional dialysis membrane. In order to avoid substrate depletion and to prolong the growth phase, a highly concentrated nutrient broth was used. The biomass production reached 60 g cell dry weight/l. The increase in extracellular lipase concentration was directly coupled with the increase of cell mass and reached a value of 230 mg/l culture supernatant. Harvesting the cells in the late growth phase, the lipase content was about 30% of the total exoproteins in the supernatant. 相似文献
13.
Phytoplankton and nutrients in the Helgoland region 总被引:3,自引:0,他引:3
Max Gillbricht 《Helgoland Marine Research》1988,42(3-4):435-467
During recent decades, phytoplankton stock on the one hand and inorganic nutrients (P and bound N) on the other have increased
considerably in the southern North Sea, as demonstrated at a permanent station (since 1962) near the island Helgoland. This
correlation between phytoplankton and inorganic P and N need not have anything to do with causality; exceptional algal blooms
have been observed and reported in the literature since in the 19th century. Furthermore, these increases (four-fold for phytoplankton and two-fold for nutrients) are in the same range as the
fluctuations from year to year under different hydrographical conditions. A detailed investigation carried out in 1981 demonstrated
the presence of a slowly growing phytoplankton population. Starting with a considerable stock of flagellates in spring, it
reached a peak in cell numbers over a long reproduction period which contrasted with the normal duration of a spring bloom
of diatoms. These processes were not related to a limited production by P or N. A considerable concentration of these nutrients
was permanently available in the form of inorganic compounds. The total amount of nutrients surpassed by far the portion incorporated
in the phytoplankton. This is a consequence of the fact that small organisms have a high metabolic rate. Therefore, the relation
between stock and production (daily production ≈stock) is completely different from that known e.g. in agriculture. The nutrients
exist during the vegetation period mainly in the form of dissolved organic matter that is accessible to plankton. The great
dynamics of this system, including a phase shifting during the year between inorganic P, N, Si, and production, indicates
the significance of permanent and fast remineralization. Calculations demonstrate that the natural nutrient content of seawater
normally satisfies the demands of phytoplankton present in the North Sea area under study. Only in the more productive coastal
region (salinity<30 associated with fresh water run-offs of low nutrient content — an unrealistic assumption in the German
Bight) might some limitation be observed. For diatoms, silicate may represent a critical component, but a high dynamic force
exists in the presence of small Si concentrations. Therefore, a lack of silicon must not represent any limitation; however,
knowledge on the silicon system is insufficient up to now.
Dedicated to Dr. Dr. h. c. Peter Kornmann on the occasion of his eightieth birthday. 相似文献
14.
Nucleotide sequence of the intron of the germline human kappa immunoglobulin gene connecting the J and C regions reveals a matrix association region (MAR) next to the enhancer.
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C Whitehurst H R Henney E E Max H W Schroeder Jr F Stüber K A Siminovitch W T Garrard 《Nucleic acids research》1992,20(18):4929-4930
15.
Interannual variability of phytoplankton productivity and related parameters in Lake Constance: no response to decreased phosphorus loading? 总被引:2,自引:0,他引:2
Tilzer Max M.; Gaedke Ursula; Schweizer Anette; Beese B?rbel; Wieser Thomas 《Journal of plankton research》1991,13(4):755-777
In meso-eutrophic Lake Constance (Germany-Austria-Switzerland),phytoplankton bioraass, pigments and water transparency, aswell as primary productivity, have been followed between 1980and 1989. During this period, municipal phosphorus loading declinedsignificantly. Since 1981, soluble reactive phosphorus (SRP)concentrations during deep lake mixing have decreased from 3.0to currently 1 6 mmol m3 at a rate of 7% year1.Nitrate concentrations, by contrast, continued to rise. Duringthe period of maximum phosphorus loading, flushing through theoutlet and sedimentation were about equally important sinksof phosphorus from the euphotic zone. Recently, however, sedimentationand subsequent burial of P in the bottom deposits contributedabout three-quarters to the overall P-losses from the systemMain reasons for this shift are unchanged settling fluxes ofphosphorus out of the euphotic zone and decreasing concentrationsof total phosphorus in the water. Only during spring, do concentrations of soluble reactive phosphoruswithin the euphotic zone decrease in proportion to the formationof particulate organic matter. Later during the season, euphoticSRP concentrations continue to be low but are no longer matchedby high plankton biomass because phosphorus is efficiently removedby settling of particles In spite of the observed dramatic decreasein phosphorus loading since 1980, chlorophyll concentrationsand water transparency, as well as annual phytoplankton productivity(300 g C m2), have not shown a consistent downward trend.However, the intensity of phosphorus regeneration within theeuphoric zone, which can be used as a measure of the degreeof nutrient limitation, is likely to have increased significantlyThe most probable explanation for the insensitivity of importanttrophic state indicators to reduced nutrient loading is that,in Lake Constance, biomass accumulation to a greater extentis controlled by losses, mainly grazing by zooplankton and sedimentation,than by primary resources. This is concluded from the observationthat phytoplankton biomass always falls far short of the nutrient-dependentcarrying capacity of the system. 相似文献
16.
17.
Terminal associations occur commonly between meiotic homologues of the two smallest (S10, S11) chromosomes in the northern race of Cryptobothrus chrysophorus when they are either heterozygous or homozygous for distal supernumerary heterochromatic segments. A detailed examination of the origin and behaviour of these associations provides convincing evidence that they are non-chiasmate in character and so cannot be explained by either pseudoterminalisation or terminalisation. The same is true of the terminal associations involved in the persistent pseudomultiples that develop between non-homologues of Heteropternis obscurella when one or both of these carry distal heterochromatic segments. In both situations the C-bands involved in such terminal associations are entire and are never interrupted by non-banded material. In Cryptobothrus, similar associations can also develop between centromere regions when these are heterozygous or homozygous for proximal supernumerary heterochromatic segments. 相似文献
18.
19.
20.
Max Häggblom Juha Apajalahti Mirja Salkinoja-Salonen 《Applied microbiology and biotechnology》1986,24(5):397-404
Summary A polychlorophenol degrader, Rhodococcus chlorophenolicus, was shown to metabolize five different chlorinated guaiacols, namely tetrachloroguaiacol, 3,4,6-trichloroguaiacol, 3,5,6-trichloroguaiacol, 3,5-dichloroguaiacol and 3,6-dichloroguaiacol. Seven different intermediate metabolites, each with three hydroxyl or methoxyl groups, were identified. Four of these metabolites were also dehalogenation products, three carrying one chlorine atom less than the parent compound, and one metabolite from tetrachloroguaiacol where two chlorine atoms had been removed. Tetrachloroguaiacol was shown to undergo reductive dehalogenation. Demethylation of guaiacol to catechol was observed with the dichloroguaiacols, but not with polychloroguaiacols.Abbreviations DCG
dichloroguaiacol
- TCG
trichloroguaiacol
- TeCG
tetrachloroguaiacol
- DCC
dichlorocatechol
- TCC
trichlorocatechol
- TeCC
tetrachlorocatechol
- TCP
trichlorophenol
- TeCP
tetrachlorophenol
- PCP
pentachlorophenol. An example of numeration
- 346-TCG
3,4,6-trichloroguaiacol
- GLC
gas liquid chromatography 相似文献