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61.
Effects of Glycerol on the Fluorescence Spectra and Chloroplast Ultrastructure of Phaeodactylum tricornutum (Bacillariophyta) 总被引:1,自引:0,他引:1
Responses of the photosynthetic activity of Phaeodactylum tricornutum (Bacillariophyta) to organic carbon glycerol were investigated. The growth rate, photosynthetic pigments, 77 K fluorescence spectra, and chloroplast ultrastructure of P. tricornutum were examined under photoautotrophic, mixotrophic, and photoheterotrophic conditions. The results showed that the specific growth rate was the fastest under mixotrophic conditions. The cell photosynthetic pigment content and values of Chl a/Chl c were reduced under mixotrophic and photoheterotrophic conditions. The value of carotenoid/Chl a was enhanced under mixotrophic conditions, but was decreased under photoheterotrophic conditions. In comparison with photoautotrophic conditions, the fluorescence emission peaks and fluorescence excitation peaks were not shifted. The relative fluorescence of photosystem (PS) Ⅰ and PS Ⅱ and the values of F685/F710 and F685/F738 were decreased. Chloroplast thylakoid pairs were less packed under mixotrophic and photoheterotrophic conditions. There was a strong correlation between degree of chloroplast thylakoid packing and the excitation energy kept in PS Ⅱ. These results suggested that the PS Ⅱ activity was reduced by glycerol under mixotrophic conditions, thereby leading to repression of the photosynthetic activity. 相似文献
62.
光强对两种硅藻光合作用、碳酸酐酶和RubisCO活性的影响 总被引:2,自引:0,他引:2
为研究海洋浮游硅藻光合固碳能力与光强的关系, 以三角褐指藻和威氏海链藻为实验材料, 测定了不同光强培养下三角褐指藻和威氏海链藻生长、光合特性、碳酸酐酶和核酮糖-1, 5-二磷酸羧化/氧化酶活性(RubisCO)的变化, 结果显示高光强促进两种硅藻的生长, 但对威氏海链藻的影响更明显。高光强导致两种硅藻叶绿素a、c含量、光系统Ⅱ的最大光化学效率和实际光化学效率明显下降, 非光化学淬灭系数明显升高, 但对光化学淬灭系数并没有明显影响。在高光下威氏海链藻和三角褐指藻胞内外碳酸酐酶活性明显升高。在高光强下培养的威氏海链藻RubisCO活性明显高于低光下培养, 但三角褐指藻正好相反, 不管高光还是低光培养威氏海链藻RubisCO活性始终高于三角褐指藻。以上结果表明不同硅藻对光强变化的响应存在差异, 它们可以通过调节光合生理特征、光合固碳关键酶和CO2供应以适应光强的变化。
相似文献
63.
64.
By means of circular dichroism (CD) spectroscopy, we have characterized the organization of the photosynthetic complexes of
the diatom Phaeodactylum tricornutum at different levels of structural complexity: in intact cells, isolated thylakoid membranes and purified fucoxanthin chlorophyll
protein (FCP) complexes. We found that the CD spectrum of whole cells was dominated by a large band at (+)698 nm, accompanied
by a long tail from differential scattering, features typical for psi-type (polymerization or salt-induced) CD. The CD spectrum
additionally contained intense (−)679 nm, (+)445 nm and (−)470 nm bands, which were also present in isolated thylakoid membranes
and FCPs. While the latter two bands were evidently produced by excitonic interactions, the nature of the (−)679 nm band remained
unclear. Electrochromic absorbance changes also revealed the existence of a CD-silent long-wavelength (∼545 nm) absorbing
fucoxanthin molecule with very high sensitivity to the transmembrane electrical field. In intact cells the main CD band at
(+)698 nm appeared to be associated with the multilamellar organization of the thylakoid membranes. It was sensitive to the
osmotic pressure and was selectively diminished at elevated temperatures and was capable of undergoing light-induced reversible
changes. In isolated thylakoid membranes, the psi-type CD band, which was lost during the isolation procedure, could be partially
restored by addition of Mg-ions, along with the maximum quantum yield and the non-photochemical quenching of singlet excited
chlorophyll a, measured by fluorescence transients. 相似文献
65.
R. J. Ritchie 《Photosynthetica》2008,46(1):115-126
A universal set of equations for determining chlorophyll (Chl) a, accessory Chl b, c, and d, and total Chl have been developed for 90 % acetone, 100 % methanol, and ethanol solvents suitable for estimating Chl in
extracts from natural assemblages of algae. The presence of phaeophytin (Ph) a not only interferes with estimates of Chl a but also with Chl b and c determinations. The universal algorithms can hence be misleading if used on natural collections containing large amounts
of Ph. The methanol algorithms are severely affected by the presence of Ph and so are not recommended. The algorithms were
tested on representative mixtures of Chls prepared from extracts of algae with known Chl composition. The limits of detection
(and inherent error, ±95 % confidence limit) for all the Chl equations were less than 0.03 g m−3. The algorithms are both accurate and precise for Chl a and d but less accurate for Chl b and c. With caution the algorithms can be used to calculate a Chl profile of natural assemblages of algae. The relative error of
measurements of Chls increases hyperbolically in diluted extracts. For safety reasons, efficient extraction of Chls and the
convenience of being able to use polystyrene cuvettes, the algorithms for ethanol are recommended for routine assays of Chls
in natural assemblages of aquatic plants. 相似文献
66.
One solution to the global crisis of antibiotic resistance is the discovery of novel antimicrobial compounds for clinical
application. Marine organisms are an attractive and, as yet, relatively untapped resource of new natural products. Cell extracts
from the marine diatom, Phaeodactylum tricornutum, have antibacterial activity and the fatty acid, eicosapentaenoic acid (EPA), has been identified as one compound responsible
for this activity. During the isolation of EPA, it became apparent that the extracts contained further antibacterial compounds.
The present study was undertaken to isolate these additional antibacterial factors using silica column chromatography and
reverse-phase high-performance liquid chromatography. Two antibacterial fractions, each containing a pure compound, were isolated
and their chemical structures were investigated by mass spectrometry and nuclear magnetic resonance spectroscopy. The antibacterial
compounds were identified as the monounsaturated fatty acid (9Z)-hexadecenoic acid (palmitoleic acid; C16:1 n-7) and the relatively unusual polyunsaturated fatty acid (6Z, 9Z, 12Z)-hexadecatrienoic acid (HTA; C16:3 n-4). Both are active against Gram-positive bacteria with HTA further inhibitory to the
growth of the Gram-negative marine pathogen, Listonella anguillarum. Palmitoleic acid is active at micro-molar concentrations, kills bacteria rapidly, and is highly active against multidrug-resistant
Staphylococcus aureus. These free fatty acids warrant further investigation as a new potential therapy for drug-resistant infections. 相似文献
67.
Maruin W. Fawley 《Journal of phycology》1989,25(3):601-604
Three chlorophyll c-type pigments were separated by reversed-phase high Performance liquid chromatography and thin-layer chromatography from pigment extracts of the prymnesiophyte, Prymnesium parvum Carter. Based on spectral characteristics, retention times, and comparison with reference pigments isolated from the diatom Phaeodactylum tricornutum Bohlin, two of these pigments were identijied as chlorophyll c1 and c2. The other pigment was identified by its absorption spectrum and thin-layer chromatography retention times as the newly described chlorophyll c3. However, in other prymnesiophytes so far examined, chlorophyll c1 and chlorophyll c3 were present with no chlorophyll cl. The discovery of chlorophyll c3 with chlorophyll c1 and chlorophyll c3 in Prymnesium parvum therefore represents the first report of this combination of pigments in prymnesiophytes. 相似文献
68.
The dominance of diatoms in turbulent waters suggests special adaptations to the wide fluctuations in light intensity that
phytoplankton must cope with in such an environment. Our recent demonstration of the unusually effective photoprotection by
the xanthophyll cycle in diatoms [Lavaud et al. (2002) Plant Physiol 129 (3) (in press)] also revealed that failure of this
protection led to inactivation of oxygen evolution, but not to the expected photoinhibition. Photo-oxidative damage might
be prevented by an electron transfer cycle around Photosystem II (PS II). The induction of such a cycle at high light intensity
was verified by measurements of the flash number dependence of oxygen production in a series of single-turnover flashes. After
a few minutes of saturating illumination, the oxygen flash yields are temporarily decreased. The deficit in oxygen production
amounts to at most 3 electrons per PS II, but continues to reappear with a half time of 2 min in the dark until the total
pool of reducing equivalents accumulated during the illumination has been consumed by (chloro)respiration. This is attributed
to an electron transfer pathway from the plastoquinone pool or the acceptor side of PS II to the donor side of PS II that
is insignificant at limiting light intensity but is accelerated to milliseconds at excess light intensity. Partial filling
of the 3-equivalents capacity of the cyclic electron transfer path in PS II may prevent both acceptor-side photoinhibition
in oxygen-evolving PS II and donor-side photoinhibition when the oxygen-evolving complex is temporarily inactivated.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
69.
Biochemical composition of three algal species proposed as food for captive freshwater mussels 总被引:4,自引:0,他引:4
Catherine M. Gatenby David M. Orcutt Daniel A. Kreeger Bruce C. Parker Vannessa A. Jones Richard J. Neves 《Journal of applied phycology》2003,15(1):1-11
To identify potential diets for rearing captive freshwater mussels, the protein, carbohydrate (CHO), and lipid contents of two green algae, Neochloris oleoabundans, Bracteacoccus grandis, and one diatom, Phaeodactylum tricornutum, were compared at different growth stages. The fatty acid and sterol composition were also identified. Protein was greatest (55–70%) for all species at late log growth stage (LL), and declined in late stationary (LS) growth. CHO was greatest at LS stage for all species (33.9–56.4% dry wt). No significant change in lipid levels occurred with growth stage, but tended to increase in N. oleoabundans. Mean lipid content differed significantly in the order: N. oleoabundans > P. tricornutum > B. grandis. Total fatty acids (TFA) were higher at LS stage compared to other stages in the two green algae, and stationary stage in the diatom. Mean unsaturated fatty acids (UFA) as %TFA was significantly higher in N. oleoabundans than the other species. The green algae contained high percentages of C-18 polyunsaturated fatty acids (PUFAs), while the diatom was abundant in C-16 saturated and mono-unsaturated fatty acids and C-20 PUFA fatty acids. Growth stage had no effect on sterol concentration of any species. B. grandis showed significantly higher sterol levels than the other species except P. tricornutum at S stage. B. grandis was characterized by predominantly 5, C-29 sterols, while N. oleoabundans synthesized 5,7, 5,7,22 , and 7, C-28 sterols. P. tricornutum produced primarily a 5,22, C-28 sterol, and a small amount of a 7,22, C-28 sterol. 相似文献
70.
Scale-up of tubular photobioreactors 总被引:1,自引:0,他引:1
E. Molina F.G. Acién Fernández F. García Camacho F. Camacho Rubio Y. Chisti 《Journal of applied phycology》2000,12(3-5):355-368
The effect of the light/dark cycle frequency on theproductivity of algal culture at differentday-averaged irradiance conditions was evaluated forPhaeodactylum tricornutum grown in outdoortubular photobioreactors. The photobioreactor scale-upproblem was analyzed by establishing the frequency oflight–dark cycling of cells and ensuring that thecycle frequency remained unchanged on scale-up. Thehydrodynamics and geometry related factors wereidentified for assuring an unchanged light/dark cycle.The light/dark cycle time in two different tubularphotobioreactors was shown to be identical when thelinear culture velocity in the large scale device(U
LL) and that in the small scale unit (>U
LS)were related as follows:ULL = \frac f 9/7 \alpha8/7 ULS.Here f is the scale factor (i.e., the ratio oflarge-to-small tube diameters), is afunction of the illuminated volumes in the tworeactors, and `dark' refers to any zone of the reactorwhere the light intensity is less than the saturationvalue. The above equation was tested in continuouscultures of P. tricornutum in reactors with 0.03 mand 0.06 m diameter tubes, and over the workableculture velocity range of 0.23 to 0.50 m s-1. Thepredicted maximum realistic photobioreactor tubediameter was about 0.10 m for assuring a cultureperformance identical to that in reactors with smaller tubes. 相似文献