紫球藻的光生物反应器培养

利用光生物反应器就碳源及其供给形式、光强和反应器的操作条件等影响紫球藻生长的因素进行了研究.结果表明:反应器良好的液体循环速度有助于培养液中每个细胞对光能的吸收利用,使紫球藻细胞可以获得较大的生长速度;利用CO2为碳源可以获得比利用NaHCO3更大的生长速度,有效地提高了紫球藻的生物量产量.在本实验条件下,细胞的生长速度和生物量产率分别达到了0.952 d-1和42.31 g/(m2.d).     

High Density Culture of Porphyridium cruentum in a 42 L Internal Airlift Loop Photobioreactor

1 INTRODUCTION Porphyridium cruentum is a kind of unicellular microalgae, which can live widely in freshwater, marine, brackish, and soil environment[1]. Great attention has been paid to its potential economic value such as the high content of essential high unsaturated fatty acids, especially arachidonic acid (AA) and eicosapentaenoic acid (EPA) (ca 50% in the total fatty acids), ploysaccharides, and synthetic pigments, especially phycoerythrin (PE)[2,3]. During cultivation, the cells…     

The production potential of eicosapentaenoic and arachidonic acids by the red algaPorphyridium cruentum

The red microalgaPorphyridium cruentum is a new source for eicosapentanoic acid (EPA) and arachidonic acid (AA) fatty acids of potential pharmaceutical value. The conditions leading to a high content of either fatty acid were investigated. The highest EPA content was obtained under conditions resulting in high growth rate (2.4% of ash free dry weight in Strain 1380-1d). High AA content was obtained under slow growth conditions and was maximal in th stationary phase or under nitrogen starvation (2.9%). Strain 1380-la had the highest content (1.9%) of arachidonic acid under exponential growth conditions. By imposing nitrogen starvation, it was possible to obtain a lipid mixture which may be separated into AA and EPA rich fractions.     

Inhibition of the growth of the red microalga porphyridium sp. by limitation of nutrient transfer

The unicellular red alga Porphyridium sp. was cultured in a medium to which increasing concentrations of its cell wall polysaccharide were added. As the polysaccharide concentration in the culture medium increased, algal growth rate and maximum cell number progressively decreased. In a different series of experiments it was shown that the polysaccharide also inhibited the rate of carbon uptake by the cells and as a result photosynthesis was also inhibited. In-vitro experiments showed that the mass transfer coefficient for nitrate, bicarbonate, phosphate and potassium decreased as the polysaccharide concentration increased. The data indicate that the polysaccharide inhibits nutrient transfer from the medium to the cells, resulting in a reduction of the growth rate.     

Lipidomic Profiling of Chylomicron Triacylglycerols in Response to High Fat Meals

Using lipidomic methodologies the impact that meal lipid composition and metabolic syndrome (MetS) exerts on the postprandial chylomicron triacylglycerol (TAG) response was examined. Males (9 control; 11 MetS) participated in a randomised crossover trial ingesting two high fat breakfast meals composed of either dairy-based foods or vegetable oil-based foods. The postprandial lipidomic molecular composition of the TAG in the chylomicron-rich (CM) fraction was analysed with tandem mass spectrometry coupled with liquid chromatography to profile CM TAG species and targeted TAG regioisomers. Postprandial CM TAG concentrations were significantly lower after the dairy-based foods compared with the vegetable oil-based foods for both control and MetS subjects. The CM TAG response to the ingested meals involved both significant and differential depletion of TAG species containing shorter- and medium-chain fatty acids (FA) and enrichment of TAG molecular species containing C16 and C18 saturated, monounsaturated and diunsaturated FA. Furthermore, there were significant changes in the TAG species between the food TAG and CM TAG and between the 3- and 5-h postprandial samples for the CM TAG regioisomers. Unexpectedly, the postprandial CM TAG concentration and CM TAG lipidomic responses did not differ between the control and MetS subjects. Lipidomic analysing of CM TAG molecular species revealed dynamic changes in the molecular species of CM TAG during the postprandial phase suggesting either preferential CM TAG species formation and/or clearance.     

Lectin may contribute to the atherogenicity of peanut oil

Peanut oil is unexpectedly atherogenic for rats, rabbits, and primates. The lesions it produces are more fibrous than fatty. The mechanism underlying the atherogenicity of peanut oil has been elusive. Randomization of peanut oil reduces significantly its atherogenic properties, but native and randomized peanut oils have similar rates of lipolysis, and rats fed the two oils absorb and transport lipids in a similar fashion. Peanut oil differs from other oils in having a relatively high lectin content, and the randomization process markedly reduces the lectin content as well. The biologically active lectin of peanut oil has an affinity for glycoproteins found specifically on arterial smooth muscle cells. Peanut lectin has been shown to stimulate growth of smooth muscle and pulmonary arterial cells. Vigorous washing of peanut oil reduces its lectin content by 46%. Compared to rabbits fed cholesterol and peanut oil, rabbits fed cholesterol and washed peanut oil exhibited less severe atherosclerosis in the aortic arch (by 9%) and in the thoracic aorta (by 31%). The data suggest that peanut oils' endogenous lectin may contribute significantly to its atherogenic properties.     

Triacylglycerols responsible for the onset of nucleation during clouding of palm olein

This paper discusses the results of an investigation to identify triacylglycerols that induce clouding of refined bleached deodorized (RBD) palm olein, which occurred within 24 h after fractionation. The experiments were conducted in a jacketed glass vessel in which the liquid sample was cooled from 70 to 23°C at a predetermined rate. Clouding began at around 28.5°C. The presence of three different types of saturated triglycerides, namely tripalmitin, dipalmitoyl-myristoylglycerol and dipalmitoyl-stearoyl-rac-glycerol, is critical in the formation of nuclei and thus clouding of the RBD palm olein. This conclusion is based on the significant increase in the relative concentration of these components in the nuclei as compared to the mother oil.     

Formation of Acrolein in the Autoxidation of Triacylglycerols with Different Fatty Acid Compositions

Fish, echium, linseed, and soybean oil triacyglycerols (TAGs) were oxidized at 50 or 60 °C to determine the effect of the polyunsaturated fatty acid composition on the volatile product formation. The analysis of the oxygen consumption and total volatile formation demonstrated that the soybean oil TAG had the highest oxidative stability followed by linseed, echium, and fish oil TAGs. Our results were in agreement with the expected average number of bis‐allylic positions of each TAG. Higher quantities of acrolein (2‐propenal) and propanal were detected using the static headspace gas chromatography method at the early stages of oxidation of echium and fish oil TAGs; however, a considerable amount of propanal and only a small amount of acrolein were found in the oxidized linseed oil TAG. The peak area ratios of acrolein to propanal were 0.115, 0.569, and 2.554 after the 8‐h oxidation of linseed, echium, and fish oil TAG, respectively, suggesting the preferential formation of acrolein, especially during the fish oil TAG oxidation. The acrolein quickly increased during the first stage of oxidation, but thereafter it either did not change or slightly decreased during the fish oil oxidation. Because fish oil induces flavor deterioration from the very early stage of the oxidation, the acrolein formation observed in the present study may be important for fish oil deterioration.     

Buried water molecules contribute to the conformational stability of a protein

This study sought to attain a better understanding of the contributionof buried water molecules to protein stability. The 3SS humanlysozyme lacks one disulfide bond between Cys77 and Cys95 andis significantly destabilized compared with the wild-type humanlysozyme (4SS). We examined the structure and stability of theI59A-3SS mutant human lysozyme, in which a cavity is createdat the mutation site. The crystal structure of I59A-3SS indicatedthat there were ordered new water molecules in the cavity created.The stability of I59A-3SS is 5.5 kJ/mol less than that of 3SS.The decreased stability of I59A-3SS (5.5 kJ/mol) is similarto that of Ile to Ala mutants with newly introduced water moleculesin other globular proteins (6.3 ± 2.1 kJ/mol), but isless than that of Ile/Leu to Ala mutants with empty cavities(13.7 ± 3.1 kJ/mol). This indicates that water moleculespartially compensate for the destabilization by decreasing hydrophobicand van der Waals interactions. These results provide furtherevidence that buried water molecules contribute to protein stability.     

Positional‐Species Composition of Triacylglycerols from the Arils of Mature Euonymus Fruits

Positional‐species composition (PSC) of 1,2,3‐triacyl‐sn‐glycerols (TAG) from the arils of mature fruits of 13 species of Euonymus L. genus was established. The residues of six major fatty acids (FA), palmitic, stearic, hexadecenoic (H), octadecenoic (O), linoleic (L), and linolenic, were present in the TAG. PSC of TAG was determined by their partial lipase hydrolysis. By using hierarchical cluster and principal component analyses, it was definitely demonstrated that separate taxonomic units forming this genus were significantly distinguished as regards PSC of TAG. In particular, the Euonymus subgenus greatly exceeded the Kalonymus subgenus in both total content of L in TAG and in the rate of its incorporation into their mid‐position, while TAG of Kalonymus were marked by a prevalence of O‐TAG and sn‐2‐O isomers. Thus, these subgenera were significantly distinct in the rate of incorporation of O and L residues in the sn‐2 position of TAG molecules. Meanwhile, the TAG from the Euonymus section species were marked by an enhanced concentration of H and the incorporation of H in UUU TAG was much more active than in other TAG types. As for positional‐type composition of TAG, saturated FA were always virtually absent in the sn‐2 position of Euonymus aril TAG.     

Acylglycerols Containing Trihydroxy Fatty Acids in Castor Oil and the Regiospecific Quantification of Triacylglycerols

Ricinoleate, a monohydroxy fatty acid in castor oil, has many industrial uses. Dihydroxy and trihydroxy fatty acids can also be used in industry. We report here the identification of diacylglycerols (DAG) and triacylglycerols (TAG) containing trihydroxy fatty acids in castor oil. The C₁₈ HPLC fractions of castor oil were used for mass spectrometry of the lithium adducts of acylglycerols to identify trihydroxy fatty acids and the acylglycerols containing trihydroxy fatty acids. Two DAG identified were triOH18:1–diOH18:1 and triOH18:0–OH18:1. Four TAG identified were triOH18:1–OH18:1–OH18:1, triOH18:0–OH18:1–OH18:1, triOH18:1–OH18:1–diOH18:1 and triOH18:0–OH18:1–diOH18:1. The structures of these two newly identified trihydroxy fatty acids were proposed as 11,12,13-trihydroxy-9-octadecenoic acid and 11,12,13-trihydroxyoctadecanoic acid. The locations of these trihydroxy fatty acids on the glycerol backbone were almost 100% at the sn-1,3 positions or at trace levels at the sn-2 position. The content of these acylglycerols containing trihydroxy fatty acids was at the level of about 1% or less in castor oil.     

Changes in the Composition of Triacylglycerols in the Fat Bodies of Bumblebee Males During Their Lifetime

The age-dependent changes in the composition of triacylglycerols (TAG) in the fat bodies of bumblebee males were studied using HPLC/MS. Two related species (Bombus terrestris and B. lucorum) were compared, with the age of the males being 0–30 days. The total amount of TAG in B. lucorum was about 2.7 times higher than that in B. terrestris for all of the ages studied. One to three-day-old males had the highest content of TAG in their fat bodies (1.6–2.3 mg/individual in B. terrestris and 3.8–4.2 mg/individual in B. lucorum). The analytical data show different patterns in both species. The qualitative composition of fatty acids in TAG was similar, but the mean relative abundance between B. terrestris and B. lucorum differed: 14:0, 7 and 14%; 16:0, 20 and 44%; 18:3, 62 and 23%; 18:1, 3 and 8%, respectively (the data is based on a GC/MS integration). A statistical evaluation of the dynamic changes in the TAG composition revealed that in B. terrestris different age classes were well separated according to their TAG composition while in B. lucorum the TAG did not change substantially during the male’s life. The TAG analyses provide more precise information on the differences between the classes studied than the FA composition alone.     

Comparison of High-Pressure Behavior of Physicochemical Properties of the Di- and Triacylglycerols Established by Ultrasonic Methods

Two samples of triacylglycerols i.e., olive oil and triolein, and one sample of diacylglycerol were investigated. In the course of compression, the density of the samples was determined by measurements of the change of piston position in a pressure chamber and volume correction due to chamber expansion under pressure. The speed of sound was evaluated from the time of flight of an ultrasonic impulse between emitting and receiving transducers placed in the high pressure chamber. The adiabatic compressibility, the intermolecular free length, the molar volume, the van der Waals’ constant b and the surface tension were evaluated from the density, the speed of sound and the average molecular mass. All tested liquids undergo a high-pressure phase transition. Discontinuities in the measured isotherms of the physicochemical parameters of the investigated oils indicate the presence of high-pressure phase transitions. Moreover the time dependent change of pressure at constant volume during the phase transition was measured. The fundamental difference in the molecular structure of these acylglycerols influences their behavior significantly under high pressure.     

Fractionation of the Triacylglycerols of Evening Primrose Oil by High-Performance Liquid Chromatography in the Silver Ion Mode

Triacylglycerols from evening primrose oil have been resolved by HPLC in the silver ion mode on a stationary phase consisted of an ion exchange medium, i.e. a silica gel matrix with boned sulphonic acid moieties, loaded with silver ions. The mobile phase was a gradient of acetone into 1,2-dichloroethane-dichloromethane initially, before acetonitrile was introduced. A mass detector was employed to monitor separations. Fractions were collected via a stream-splitter for identification and quantification by gas chromatography as methyl esters. Excellent resolution was obtained, and species differing in saturation from disaturated- monoenoic to monodienoic-ditrienoic were resolved and quantified.     

Dirt and Grime in Bathrooms: Their Chemical Composition and the Origin of the Triacylglycerols Contained Therein

Bathrooms provide environments that encourage the formation of biofilms and mold on the hard surfaces of bathtubs and tile walls. To prevent such microbe-produced grime from spreading, methods such as bleaching and scrubbing may be commonly employed. The removal of dirt before the mold can grow is much more important, however, and therefore clarification of the composition and the accumulation mechanism of dirt and grime is needed. The grime collected from the shower walls of home bathrooms in our previous study consisted mainly of calcium soap, surfactants, fatty acids, and triacylglycerols. The triacylglycerols were suggested as playing an important role in the accumulation of grime, and in the present study we focused on their detailed composition and origin. A non-aqueous reverse-phase HPLC-ESI-MS/MS enabled us to characterize the small amount of triacylglycerols, but their MS/MS spectra were complicated by the presence of a number of product ions. Furthermore, there were no characteristic ions that allowed us to identify the triacylglycerols. Therefore, we adopted a new methodology in which only two ESI-MS/MS spectra corresponding to two m/z ranges in MS spectra (m/z 800–900 and 850–950) were acquired instead of a number of MS/MS spectra corresponding to each MS signal. This made it possible to estimate the origin of triacylglycerols by comparing the spectral patterns of the grime with those of the standard materials, with the desired convenience and quickness. The origin of the triacylglycerols should be closely related to the accumulation mechanism, though the triacylglycerols in the grime examined in the present study came mostly from human sebum instead of bath products and other sources.

Different cellular response mechanisms contribute to the length-dependent cytotoxicity of multi-walled carbon nanotubes

To date, there has not been an agreement on the best methods for the characterisation of multi-walled carbon nanotube (MWCNT) toxicity. The length of MWCNTs has been identified as a factor in in vitro and in vivo studies, in addition to their purity and biocompatible coating. Another unresolved issue relates to the variable toxicity of MWCNTs on different cell types. The present study addressed the effects of MWCNTs'' length on mammalian immune and epithelial cancer cells RAW264.7 and MCF-7, respectively. Our data confirm that MWCNTs induce cytotoxicity in a length- and cell type-dependent manner. Whereas, longer (3 to 14 μm) MWCNTs exert high toxicity, especially to RAW264.7 cells, shorter (1.5 μm) MWCNTs are significantly less cytotoxic. These findings confirm that the degree of biocompatibility of MWCNTs is closely related to their length and that immune cells appear to be more susceptible to damage by MWCNTs. Our study also indicates that MWCNT nanotoxicity should be analysed for various components of cellular response, and cytotoxicity data should be validated by the use of more than one assay system. Results from chromogenic-based assays should be confirmed by trypan blue exclusion.     

Study of Some Experimental Parameters in the Synthesis of Triacylglycerols with CLA Isomers and Structural Analysis

The present research deals with the synthesis of structured triacylglycerols (TAG) by enzymatic treatment of sn-1,3-diacylglycerol (sn-1,3-DAG) with conjugated linoleic acid (CLA) isomers using the immobilized lipase from Rhizomucor miehei (Lipozyme^® IM) under different experimental conditions. In particular, the influence of reaction parameters, such as temperature, enzymatic load, reaction time and DAG/CLA ratio has been evaluated using an experimental design software with a screening objective. Two responses have been selected, they are the percentage of CLA isomers in total TAG and in the sn-2- position and a three-level-4-factor fractional factorial experimental design was used to screen the variables. The results showed that the selected experimental variables have an influence on the enzymatic reaction, in particular, the DAG/CLA substrate ratio and the temperature, both of which inversely correlated with CLA incorporation, but also the enzymatic load and the reaction time, both directly correlated with CLA incorporation. The best results for CLA isomer % content both in total TAG (46.3%) and in the sn-2- position (52.2%) were obtained at 40 °C for 96 h, with 20% enzymatic load and a 0.5 reactive ratio.     

Elucidation of Kinetic and Symmetry Effects on the Viscosity and Flow Behavior of Stearic and Oleic Triacylglycerols

The flow behavior and viscosity of TAGs containing oleic and stearic acids were examined in the liquid phase as well as at temperatures close to the onset of crystallization by means of a temperature‐controlled rheometer. Gelling and crystallization transitions were unambiguously identified by singularities in the viscosity versus temperature curves of the TAGs. An additional transition between the gelling and onset of crystallization temperatures, attributed to the reorganization of the gel, was observed in the symmetrical TAGs only. The effect of the cooling rate, ranging between 0.1 and 5 °C/min, was investigated. The flow behavior of the studied TAGs was shown to be strongly determined by structural parameters (symmetry, degree of unsaturation). The flow behavior was also affected significantly by the cooling rate, suggesting that to certain extents the flow behavior determined by structural parameters could be changed by manipulating the cooling rate. The study confirmed that TAG crystallization is initiated by and depends, at least in part, on complex molecular short range order transformations occurring in the melt. The findings of the study may be valuable for evaluating systems and equipment that are involved in the storage, handling and processing of materials incorporating these TAGs.     

Getting ready to translate: cytoplasmic maturation of eukaryotic ribosomes

The ribosome is the 'universal ribozyme' that is responsible for the final step of decoding genetic information into proteins. While the function of the ribosome is being elucidated at the atomic level, in comparison, little is known regarding its assembly in vivo and intracellular transport. In contrast to prokaryotic ribosomes, the construction of eukaryotic ribosomes, which begins in the nucleolus, requires >200 evolutionary conserved non-ribosomal trans-acting factors, which transiently associate with pre-ribosomal subunits at distinct assembly stages and perform specific maturation steps. Notably, pre-ribosomal subunits are transported to the cytoplasm in a functionally inactive state where they undergo maturation prior to entering translation. In this review, I will summarize our current knowledge of the eukaryotic ribosome assembly pathway with emphasis on cytoplasmic maturation events that render pre-ribosomal subunits translation competent.