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1.
The diatoms Chaetoceros sp., Skeletonema costatum and Thalassiosira pseudonana were grown with different irradiances of white and of blue-green light, and with a mixture of blue-green plus 6.5 mol m –2 s –1 of white light. Exponential growth rates were higher in mixed blue for the first two, while T. pseudonana grew faster in white light but, in all cases, mean cell division rates did not differ with increasing irradiances. Harvesting in stationary, rather than in late exponential growth phase, resulted in higher protein contents for Chaetoceros sp. and S. costatum, but for T. pseudonana the highest value was in the exponential phase. The highest protein content was in blue-green light for the three species and it increased with irradiance. As to other fractions, the three strains showed different responses, related to quality and quantity, as well as to culture ages. 相似文献
2.
Competition experiments between Phaeodactylum tricornutum and Skeletonema costatum showed that even at temperatures higher than 10°C ( i.c. 14°C), the development of Skeletonema can be favoured by adjusting nutrient levels and nutrient ratios. Low NSi ratios were found to favour Skeletonema. Additionally, high NP ratios further enhanced the ability of Skeletonema to dominate the cuftures. Contrary to some statements in literature, it seems that high concentrations of silicates are more important for the dominance of Skeletonema costatum in large-scale cultures than just low temperatures. This finding is important with regard to stimulating the blooming of Skeletonema costatum in natural phytoplankton populations as food for bivalve molluscs. 相似文献
3.
The green micro-algae Chlamydomonas reinhardtiiand Dunaliella tertiolecta were cultivated undermedium-duration square-wave light/dark cycles with acycle time of 15 s. These cycles were used to simulatethe light regime experienced by micro-algae inexternally-illuminated (sunlight) air-lift loopbioreactors with internal draft tube. Biomass yieldin relation to light energy was determined as gprotein per mol of photons (400–700 nm). Between 600and 1200 mol m -2 s -1 the yield at a10/5 s light/dark cycle was equal to the yield atcontinuous illumination. Consequently, provided thatthe liquid circulation time is 15 s, a considerabledark zone seems to be allowed in the interior ofair-lift loop photobioreactors (33% v/v) without lossof light utilization efficiency. However, at a 5/10 slight/dark cycle, corresponding to a 67% v/v darkzone, biomass yield decreased. Furthermore, bothalgae, C. reinhardtii and D. tertiolecta,responded similarly to these cycles with respect tobiomass yield. This was interesting because they werereported to exhibit a different photoacclimationstrategy. Finally, it was demonstrated that D.tertiolecta was much more efficient at low (average)photon flux densities (57–370 mol m -2s -1) than at high PFDs (> 600 mol m -2s -1) and it was shown that D. tertiolectawas cultivated at a sub-optimal temperature (20 °C). 相似文献
4.
Imposex – the superimposition of male sexual organs (penis and vas deferens) onto female Neogastropods such as Hexaplex trunculus (Linné, 1758) – is used world-wide as a biomarker of ecological impact of organotin based antifouling biocides (TBT and TPhT).
To limit the impact of organotin pollution, since January 1, 2003, the International Maritime Organization (IMO) has enacted
a global ban on the use of organotin compounds in antifouling systems. It is important to record imposex levels and organotin
contamination before the implementation of the ban, in order to assess the current situation and be able, in the future, to
verify the effects of the International Protocol. In this paper, recent imposex data measured in populations of Hexaplex trunculus from three different Mediterranean regions are compared: the Ligurian Sea (Italy), the Lagoon of Venice (Italy) and the western
coast of Istria (Croatia). In the two former locations, a partial ban on TBT has been in force for vessels less than 25 m
since 1982, while in the latter region no restrictions on organotin antifouling paints have been applied yet. Gastropod samples
collected from the Venice lagoon were analysed with an acid extraction followed by Grignard derivatisation, clean up and GC-MS
determination, in order to relate the levels of TBT, TPhT and their metabolites with the imposex degree detected. Biological
data show that the levels of imposex were very high (VDS from 4.3 to 5) in all the sampling sites considered, particularly
in the Croatian coast stations. The concentrations of organotin compounds – butyltins and phenyltins – measured in the samples
from the lagoon of Venice were found to partition differently in the visceral coil and in the rest of the soft body of the
analysed organisms. 相似文献
5.
Organotin compounds (OTC) are toxic towards all living organisms. The application of organitin-based antifouling systems is becoming the main source of OTC in the ocean. Harbor sediments and water contain large deposits of organotin compounds due to application of antifouling systems in the shipping industry. OTC contamination presents a potential risk to the marine environment. Sediment and water samples were collected in 2009 from Gdynia Harbor. For all the analyzed organotin compounds, the mean concentration values were determined: water samples monobutyltin (MBT): 13.2, dibutyltin (DBT): 16.7, tributyltin (TBT): 60.7 (ng cation dm?3), and sediment samples MBT: 261.4, DBT: 751.9, TBT: 2148.2 (ng cation g?1 d.w.). The estimated content of monophenyltin (MPhT), diphenyltin (DPhT), triphenyltin (TPhT), monooctyltin (MOT), dioctyltin (DOT), and tricyclohexyltin (TCHT) were below the detection limit of the applied method. It was found that the content of organic matter, the amount of fine fraction, and the pH all play a significant role in the distribution and sorption process of OTC between the water and the sediment on the bottom. Compared to an earlier study, the concentrations of all OTC are much lower, confirming that the applied legislation has had a positive impact. 相似文献
6.
A mass spectrometric 16O 2/ 18O 2-isotope technique was used to analyse the rates of gross O 2 evolution, net O 2 evolution and gross O 2 uptake in relation to photon fluence rate by Dunaliella tertiolecta adapted to 0.5, 1.0, 1.5, 2.0 and 2.5 M NaCl at 25°C and pH 7.0.At concentrations of dissolved inorganic carbon saturating for photosynthesis (200 M) gross O 2 evolution and net O 2 evolution increased with increasing salinity as well as with photon fluence rate. Light compensation was also enhanced with increased salinities. Light saturation of net O 2 evolution was reached at about 1000 mol m -2s -1 for all salt concentrations tested. Gross O 2 uptake in the light was increased in relation to the NaCl concentration but it was decreased with increasing photon fluence rate for almost all salinities, although an enhanced flow of light generated electrons was simultaneously observed. In addition, a comparison between gross O 2 uptake at 1000 mol photons m -2s -1, dark respiration before illumination and immediately after darkening of each experiment showed that gross O 2 uptake in the light paralleled but was lower than mitochondrial O 2 consumption in the dark.From these results it is suggested that O 2 uptake by Dunaliella tertiolecta in the light is mainly influenced by mitochondrial O 2 uptake. Therefore, it appears that the light dependent inhibition of gross O 2 uptake is caused by a reduction in mitochondrial O 2 consumption by light.Abbreviations DCMU
3-(3, 4-dichlorophenyl)-1, 1-dimethylurea
- DHAP
dihydroxy-acetonephosphate
- DIC
dissolved inorganic carbon
- DR a
rate of dark respiration immediately after illumination
- DR b
rate of dark respiration before illumination
- E 0
rate of gross oxygen evolution in the light
- NET
rate of net oxygen evolution in the light
- PFR
photon fluence rate
- RubP
rubulose-1,5-bisphosphate
- SHAM
salicyl hydroxamic acid
- U 0
rate of gross oxygen uptake in the light 相似文献
7.
Summary Alloplasmic common wheat ( Triticum aestivum L. cultivais Penjamo 62 and Siete Cerros 66) with cytoplasms of wheatgrass ( Agropyron trichophorum and Ag. glaucum) showed two aberrant phenotypes, i.e., gross reduction in plant vigor and male sterility. Plant vigor and male fertility were restored by cytoplasm-specific telocentric chromosomes (telosomes). Studies on carbon assimilation and consumption and on oxygen evolution and uptake showed that maximum rates of apparent photosynthesis were significantly lower in the alloplasmic lines than in their corresponding euplasmic lines and that the telosomes restored a normal level of photosynthesis. The decreased apparent photosynthetic rates in the alloplasmic lines were shown to be not due to decreased rates of true photosynthesis but to increased rates of dark respiration in the green leaves. In contrast, dark respiration in the roots was significantly low in the alloplasmic lines. The alloplasmic lines also showed decreased rates of respiratory consumption of new photosynthates. These results suggest that growth depression and male sterility in the alloplasmic lines are related to aberrant mitochondrial function, which is compensated for by cytoplasm-specific telosomes. 相似文献
8.
A study on the effects of selected organic chlorides of tin on the extent of hydration of the lipid bilayer of erythrocyte ghosts from pig blood is presented. The following compounds were used, dibutyltin dichloride (DBT), tributyltin chloride (TBT), diphenyltin dichloride (DPhT) and triphenyltin chloride (TPhT). The degree of membrane hydration was measured by the ATR FTIR technique, which makes it possible to estimate the level of carbonyl and phosphate group hydration in lipids of membranes. Other measurements were made with a fluorescence technique involving a laurdan probe. Tin organic compounds caused dehydration of the lipid bilayer of ghosts in the region of the carbonyl groups. DBT and TBT produced weak dehydration in the region of the phosphate group, whereas DPhT and TPhT increased hydration. The results allow one to determine the location of organotin compounds within a membrane, and show that TBT penetrates the membrane the deepest and DBT the shallowest. Phenyl tin compounds penetrate membranes to an intermediate depth. The results obtained indicate that the destructive properties of the organometallic compounds depend mostly on their effect on hydration of the membrane. 相似文献
9.
Organotin compounds examined in this study exhibited a relative order of potency for induction of in vitro hemolysis in human erythrocytes as follows: tri-n-butyltin > tri-n propyltin > tetra-n-butyltin > triphenyltin chloride > tri-n-ethyltin bromide > dibutyltin dichloride > stannous chloride > tri-n-methyltin chloride = butyltin chloride dihydroxide. All of the organotin compounds induced erythrocyte shape transformation from the normal discocyte to an echinocyte and, in addition, triphenyltin chloride, tetra-n-butyltin and tri-n-ethyltin bromide also elicited stomatocyte formation at higher concentrations. Select organotin compounds also formed tin-containing aggregates within the plasma membrane. The relative order of effectiveness for organotin induction of intramembranous aggregates was tri-n-butyltin > tri-npropyltin > tetra-n-butyltin > tri-n-ethyltin bromide, which was based upon the lowest concentration at which they were observed. These results support the previously suggested theory that organotins are membrane effectors because of their comparatively high hydrophobic, lipid partitioning properties. The relatively lipophilic compound, triphenyltin chloride, appeared to be anomalous because it did not readily promote hemolysis or induce the formation of intramembranous aggregates in human erythrocytes. A log-linear statistical model demonstrated an association of hemolysis with both tri-n-butyltin aggregate formation and shape transformation. Select organotin compounds should be useful probes in membrane studies because of their numerous effects.Abbreviations DBT
dibutylin dichloride
- MBT
butyltinchloride dihydroxide
- SnCl 2
stannous chloride
- TBT
tri-n-butyltin
- TET
tri-n-ethyltin bromide
- TMT
tri-n-methyltin chloride
- TPhT
triphenyltin chloride
- TPT
tri-n-propyltin
- TTBT
tetra-n-butyltin 相似文献
10.
A nuclear transformation system for the microalga Dunaliella tertiolecta was explored using electroporation. Plasmids incorporating the D. tertiolecta RbcS1 5′ and 3′ untranslated regions flanking the Streptoalloteichus hindustanus gene encoding bleomycin resistance ( ble) were introduced into D. tertiolecta cells both transiently and stably. Southern hybridisation was used to examine the fate of the plasmid following electroporation and revealed that the DNA was entering the cells but was quickly degraded. Using the same procedure one stably transformed line was recovered. 相似文献
11.
Summary Curves were established for the pH response of respiration on eleven substrates by Azotobacter vinelandii and Acetobacter diazotrophicus. With every substrate the optimal pH for A. diazotrophicus was lower than for A. vinelandii. The optimal hydrogen ion concentration for A. diazotrophicus was 5 fold to 365 fold greater than for A. vinelandii depending upon the substrate. In general, A. diazotrophicus supports respiration over a wider pH range than does A. vinelandii.Dedicated to the memory of Professor John G. Torrey 相似文献
12.
We examined the in situ CO 2 gas-exchange of fruits of a tropical tree, Durio zibethinus Murray, growing in an experimental field station of the Universiti Pertanian Malaysia. Day and night dark respiration rates were exponentially related to air temperature. The temperature dependent dark respiration rate showed a clockwise loop as time progressed from morning to night, and the rate was higher in the daytime than at night. The gross photosynthetic rate was estimated by summing the rates of daytime dark respiration and net photosynthesis. Photosynthetic CO 2 refixation, which is defined as the ratio of gross photosynthetic rate to dark respiration rate in the daytime, ranged between 15 and 45%. The photosynthetic CO 2 refixation increased rapidly as the temperature increased in the lower range of air temperature T
c ( T
c <28.5 °C), while it decreased gradually as the temperature increased in the higher range ( T
c 28.5 °C). Light dependence of photosynthetic CO 2 refixation was approximated by a hyperbolic formula, where light saturation was achieved at 100 mol m –2 s –1 and the asymptotic CO 2 refixation was determined to be 37.4%. The estimated gross photosynthesis and dark respiration per day were 1.15 and 4.90 g CO 2 fruit –1, respectively. Thus the CO 2 refixation reduced the respiration loss per day by 23%. The effect of fruit size on night respiration rate satisfied a power function, where the exponent was larger than unity. 相似文献
13.
The normal high-performance liquid chromatography with UV detection was applied for the determination of tributyltin chloride (TBT), triphenyltin chloride (TPhT), tetraphenyltin (TrPhT), triethyltin chloride (TET) and tetraethyltin (TrET) from flour samples. The separation was performed in the isocratic mode on cyanopropyl column with a mobile phase of hexane-acetonitrile-THF (97/1/2). Under the experimental conditions used, quantitative limit of TBT, TPhT, TrPhT, TET and TrET are 0.95, 0.46, 0.97, 0.75 and 0.96 microg/ml, respectively. Microwave-assisted extraction of organotin (OT) compounds at 100 degrees C with an extraction time of 3 min was described. The extraction of organotin can be finished in acetic acid-hexane (20/80) medium. The quantitative extraction of five organotin compounds was achieved with recoveries ranging from 88 to 101% R.S.D. 3-8%. 相似文献
14.
The green algae D. tertiolecta, the flagellate I. galbana and the diatom C. gracilis were grown in batch cultures. The organisms were analysed for lipid class composition at the logarithmic and stationary growth phases using the Chromarod-Iatroscan thin layer chromatography with flame ionization detection (TLC-FID) system.There were major differences in lipid class production among the organisms investigated, but few differences in lipid class distribution between log phase and stationary phase cultures of D. tertiolecta and I. galbana. C. gracilis displayed the general trend exhibited in diatom metabolism, which can be characterized by an increase in triacylglycerol synthesis in situations of stress. 相似文献
15.
We examined the importance of temperature (7°C or 15°C) and soil moisture regime (saturated or field capacity) on the carbon (C) balance of arctic tussock tundra microcosms (intact blocks of soil and vegetation) in growth chambers over an 81-day simulated growing season. We measured gaseous CO 2 exchanges, methane (CH 4) emissions, and dissolved C losses on intact blocks of tussock ( Eriophorum vaginatum) and intertussock (moss-dominated). We hypothesized that under increased temperature and/or enhanced drainage, C losses from ecosystem respiration (CO 2 respired by plants and heterotrophs) would exceed gains from gross photosynthesis causing tussock tundra to become a net source of C to the atmosphere. The field capacity moisture regime caused a decrease in net CO 2 storage (NEP) in tussock tundra micrososms. This resulted from a stimulation of ecosystem respiration (probably mostly microbial) with enhanced drainage, rather than a decrease in gross photosynthesis. Elevated temperature alone had no effect on NEP because CO 2 losses from increased ecosystem respiration at elevated temperature were compensated by increased CO 2 uptake (gross photosynthesis). Although CO 2 losses from ecosystem respiration were primarily limited by drainage, CH 4 emissions, in contrast, were dependent on temperature. Furthermore, substantial dissolved C losses, especially organic C, and important microhabitat differences must be considered in estimating C balance for the tussock tundra system. As much as 20% of total C fixed in photosynthesis was lost as dissolved organic C. Tussocks stored 2x more C and emitted 5x more methane than intertussocks. In spite of the limitations of this microcosm experiment, this study has further elucidated the critical role of soil moisture regime and dissolved C losses in regulating net C balance of arctic tussock tundra. 相似文献
16.
The response of net photosynthesis and apparent light respiration to changes in [O 2], light intensity, and drought stress was determined by analysis of net photosynthetic CO 2 response curves. Low [O 2] treatment resulted in a large reduction in the rate of photorespiratory CO 2 evolution. Lightintensity levels influenced the maximum net photosynthetic rate at saturating [CO 2]. These results indicate that [CO 2], [O 2] and light intensity affect the levels of substrates involved in the enzymatic reactions of photosynthesis and photorespiration. Intracellular resistance to CO 2 uptake decreased in low [O 2] and increased at low leaf water potentials. This response reflects changes in the efficiency with which photosynthetic and photorespiratory substrates are formed and utilized. Water stress had no effect on the CO 2 compensation point or the [CO 2] at which net photosynthesis began to saturate at high light intensity. The relationship between these data and recently published in-vitro kinetic measurements with ribulose-diphosphate carboxylase is discussed.Abbreviations
C
w
intracellular CO 2 concentration
-
F
gross
gross photosynthesis
-
F
net
net photosynthesis
-
I
light intensity
-
R
L
light respiration rate
-
r
c
carboxylation resistance
-
r
8
leaf gas-phase resistance
-
r
i
intracellular resistance; to CO 2 uptake
-
r
t
resistance to CO 2 flux between the intercellular spaces and the carboxylation sites
-
T
L
leaf temperature
-
t
leaf water potential
-
CO 2 compensation point 相似文献
17.
The work addressed bioenergetic, metabolic and physiological responses ofthe green alga Dunaliella salina to sulfur (S)-deprivation. Photo-autotrophically grown cells were suspended in a medium in which thesulfates were replaced by chloride salts. Growth characteristics, pigmentcontent, rates of photosynthesis and respiration, as well as endogenoussubstrate (starch and protein) accumulation were monitored as a functionof time under S-deprivation. Lack of S from the growth medium had adifferential effect on photosynthesis and respiration. The rate oflight-saturated photosynthesis declined semi-exponentially with time,whereas the activity of respiration remained fairly constant over a periodof up to 100 h in S-deprived medium. Cell division and `packed cell volumeincrease' declined in tandem with the decline in the rate of photosynthesis. There was gradual loss of chlorophyll from the cells and a concomitant lossof photochemically competent system-II reaction centers, whereas theconcentration of system-I remained largely unaffected under S-deprivation. Cells altered the partition of photosynthate between starch and protein sothat control steady-state starch/protein ratios in the light (0.1: 1, w: w)gradually increased up to about 1: 1 as a function of S-deprivation. Sealed Dunaliella salina cultures, in which the capacity of photosynthesisdeclined to levels lower than that of respiration, consumed dissolvedoxygen and became anaerobic in the light. These cultures, however, did notactivate the reversible `hydrogenase pathway' and did not produceH 2 gas. Instead, under extended S-deprivation, cells maintained alow-level cycling of O 2 and CO 2 between photosynthesis andrespiration that resulted in no net exchange of gases. Such low-level cyclingof photosynthesis and respiration was sufficient to ensure the generation ofATP needed for survival of the organism under protracted S-deprivationconditions. 相似文献
18.
Various ecophysiological investigations on carnivorous plants in wet soils are presented. Radial oxygen loss from roots of Droseraceae to an anoxic medium was relatively low 0.02 – 0.07 mol(O 2) m – 2 s –1 in the apical zone, while values of about one order of magnitude greater were found in both Sarracenia rubra roots and Genlisea violacea traps. Aerobic respiration rates were in the range of 1.6 – 5.6 mol kg –1 (f.m.) s –1 for apical root segments of seven carnivorous plant species and 0.4 – 1.1 mol kg –1 (f.m.) s –1 for Genlisea traps. The rate of anaerobic fermentation in roots of two Drosera species was only 5 – 14 % of the aerobic respiration. Neither 0.2 mM NaN 3 nor 0.5 mM KCN influenced respiration rate of roots and traps. In all species, the proportion of cyanide-resistant respiration was high and amounted to 65 – 89 % of the total value. Mean rates of water exudation from excised roots of 12 species ranged between 0.4 – 336 mm 3 kg –1 (f.m.) s –1 with the highest values being found in the Droseraceae. Exudation from roots was insensitive to respiration inhibitors. No significant difference was found between exudation rates from roots growing in situ in anoxic soil and those kept in an aerated aquatic medium. Carnivorous plant roots appear to be physiologically very active and well adapted to endure permanent soil anoxia. 相似文献
19.
Eucalyptus camaldulensis Dehnh. seedlings inoculated with Pisolithus tinctorius (Pers.) Coker & Couch and Thelephora terrestris Ehrl. per Fr. were grown in well watered soil ( s –0.03 MPa) or subjected to a long-term soil water stress of up to –1.0 MPa over 13-week period in a glasshouse. After 13 weeks, all seedling containers were watered to field capacity and then water was withheld from the E. camaldulensis seedlings to induce a short-term drought. Diurnal measurements of seedling photosynthesis rate (A), leaf stomatal conductance (g) and leaf water potential ( p) were completed before, during, and after the short term drought. Although they were growing in an equal soil volume, photosynthesis rate (A), leaf stomatal conductance and leaf water potential ( p) of larger seedlings with P. tinctorius ectomycorrhizae were similar to those of smaller seedlings colonized with T. terrestris during the short-term drought period. Seedlings inoculated with Pisolithus tinctorius maintained higher photosynthesis rates over the course of the short-term drought. Thus, P. tinctorius ectomycorrhizae appear to be more efficient than those of T. terrestris in assisting seedlings to maintain gas exchange and photosynthesis under limited soil moisture conditions. 相似文献
20.
We examine the issue of prochlorophyte origins and provide analyses which highlight the limitations of inferring evolutionary trees from anciently diverged sequences that have markedly different GC contents. Under these conditions we have found that current tree reconstruction methods strongly group together sequences with similar GC contents, whether or not the sequences share a common ancestor. We provide 3 psbA termini sequence for Prochloron didemni and find it does not have the 7 amino acid deletion that occurs in Chl a/b chloroplasts and Prochlorothrix hollandica. This is consistent with the recent findings of a Chl c like pigment in the light harvesting system in other prochlorophytes but apparently absent in P. hollandica. From these observations we suggest that P. hollandica is the prochlorophyte most closely related to Chl a/b containing chloroplasts and hence the most appropriate prokaryotic model for higher plant Chl a/b photosynthesis. 相似文献
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