大豆饱和脂肪酸组分改良研究进展

为了更好地满足消费者的需要,遗传改良豆油中脂肪酸含量已经取得很大进展,并有3个油分改良的大豆品种已经商品化,其油分中亚麻酸的含量已经从原来的8%降到了1%,油酸含量也已从25%增加到80%,棕榈酸从11%降到小于4%。传统育种和基因工程育种都是遗传改良大豆油的手段。阐述了遗传改良、基因型和表现型的选择等多方法对脂肪酸的影响,总结了大豆饱和脂肪酸组翻改良的主要进展。     

UC blood-derived mesenchymal stromal cells: an overview

The UC is a readily available source of blood that may be used for analysis and treatment. Some authors suggest that within the UC blood (UCB) are cells with potential for differentiation down mesenchymal lineages. Isolation and characterization of these cells has been accomplished in some centers. Differentiation of these cells down multiple lineages has been documented. Surface marker expression and gene expression profiling has been performed, and mesenchymal stromal cells (MSC) from BM and adipose tissue have been compared with those derived from UCB. The use of UCB-derived stem cells has been investigated in pre-clinical studies. As this field is rapidly advancing, this review summarizes the current state of our knowledge of MSC derived from UCB.     

The physicochemical and biochemical characteristics of the cell walls in M+ and M- variants of Streptococcus group A type 29

The amino acid composition of cell walls and surface proteins, isolated from virulent (M+) and avirulent (M-) streptococcal strains (group A, type 29) has been determined by the method of E. H. Beachey et al. The kinetics of the lysis and proteolysis of streptococcal cell walls with muramidase and protease obtained from Actinomyces levoris and streptolysin has been studied. The constants describing the progress rates of these processes has been determined; their values in case of both lysis and proteolysis are higher in virulent strains than in avirulent ones.     

Inhibition of collagenase by Cr(III): its relevance to stabilization of collagen

Bacterial collagenase has now been reacted with a select series of Cr(III) complexes and modifications in the activity of chromium-modified collagenase has been deduced from the extent of hydrolysis of (2-furanacryloyl-L-leucyl-glycyl-L-prolyl-L-alanine), FALGPA. A homologous series of Cr(III) complexes with dimeric, trimeric and tetrameric structures as in 1, 2 and 3 respectively has been investigated for their ability to inhibit the action of collagenase against FALGPA. Whereas competitive and non-competitive modes of inhibition of collagenase are expressed by 1, (dimer) and 2, (trimer) respectively, the tetramer, 3, exhibits poor affinity to collagenase and the inhibition of the enzyme activity is uncompetitive. Evidence for different modes of inhibition of collagenase depending on the nature of Cr(III) species has been presented in this work. Circular dichroism and gel electrophoresis data on Cr(III) modified collagenase corroborate the hypothesis that the inhibition of collagenase by the heavy metal ion arises from secondary and quaternary structural changes in the enzyme. The implications of the observed Cr(III) species specific inhibition of collagenase in gaining new insight into the mechanism of stabilization of collagen by Cr(III) are discussed.     

Selenoprotein expression and function—Selenoprotein W

Selenoprotein W (SeW) is a small selenoprotein (85 to 88 amino acids) first identified in sheep suffering from selenium deficiency. The levels are highest in muscle, heart (except rodents) spleen and brain. The deduced amino acid sequence has been obtained for mice, rats, monkeys, humans, sheep, pigs, fish and chickens. The sequences of SeW are identical in rats and mice as well as monkeys and humans. In all eight species of animals cysteine is present at residue number 9 and selenocysteine at residue number 13. Residue number 37 is cysteine in six species of animal with fish and chickens as the exceptions. Of those examined, the rodent SeW is the only one containing four cysteines whereas the others contain only two cysteines. Glutathionylaltion has been shown for SeW from rats and monkeys but has not been confirmed for this selenoprotein from the other six animals. The biological function of SeW has not been definitely identified. Evidence has been obtained that it can serve as an antioxidant, responds to stress, involved in cell immunity, specific target for methylmercury, and has thioredoxin-like function.     

Synthesis and characterization of carnitine nitro-derivatives

Nitric oxide (NO) acts as an autacoid molecule that diffuses from its endothelial production site to the neighboring muscular cells. NO-donors are often used to mimic the physiological effects of NO in biological systems. Organic nitrates are commonly used as NO-donors; the most popular, glycerol trinitrate (GTN), has been used in therapy for more than a century. Carnitine nitrates have been synthesized using an endogenous non-toxic molecule: (L)-carnitine. The biotransformation of carnitine nitro-derivatives in biological fluids (saliva and blood plasma) and in red blood cells (RBC) has been monitored by an electrochemical assay and the interaction of carnitine nitrates with the plasma membrane carnitine transporter has been investigated. Differences in the way carnitine nitro-derivatives are metabolized in biological fluids and cells and transported by OCTN2 transporter are modulated by the chemical structures and by the length of the acyl template which carries the nitro-group.     

The ApoE gene of Alzheimer's disease (AD)

The ApoE gene responsible for the Alzheimer's disease has been examined to identify functional consequences of single-nucleotide polymorphisms (SNPs). Eighty-eight SNPs have been identified in the ApoE gene in which 31 are found to be nonsynonymous, 8 of them are coding synonymous, 33 are found to be in intron, and 3 are in untranslated region. The SNPs found in the untranslated region consisted of two SNPs from 5′ and one SNP from the 3′. Twenty-nine percent of the identified nsSNPs have been reported as damaging. In the analysis of SNPs in the UTR regions, it has been recognized that rs72654467 from 5′ and rs71673244 from 5′ and 3′ are responsible for the alteration in levels of expression. Both native and mutant protein structures were analyzed along with the stabilization residues. It has been concluded that among all SNPs of ApoE, the mutation in rs11542041 (R132S) has the most significant effect on functional variation.     

Differences in conformational behavior of ATA and TAT sequences in single strand DNA trimer.

The conformational behavior of single strand (ss) TAT and ATA trimers of DNA have been studied by computational chemistry tools including CICADA software interfaced with AMBER molecular mechanics and dynamics. The Single-Coordinate-Driving (SCD) method has been used in conjunction with molecular dynamics simulated annealing. It has been revealed that the conformational flexibility of each sequence differs substantially from the other one. Four common conformational families have been found for both trimers. These are: helical, reverse-stacked (base 3), half-stacked (base 3), reverse-stacked (base 1). However, the energies of conformers representing the families are different for both the studied systems. An additional conformational family, bulged, has been found for ss(ATA), while ss(TAT) has been found also in half-stacked (base 1) conformation. In general, ss(TAT) exhibits a higher number of low energy conformations while ss(ATA) shows one interesting low energy conformational interconversion between reverse-stacked (A3) family and half-stacked (A3) family. The high conformational variability of the trimers has been confirmed by flexibility analysis and by molecular dynamics simulations, which have also shown the conformational stability of single conformational families. It has been concluded that the methodology used is able to provide a very detailed picture of the conformational space of these molecules.     

Studies on the apoproteins of the major lipoprotein of the yolk of hen's eggs. I. Isolation and properties of the low-molecular-weight apoproteins.

In a continuing study of protein-lipid interactions in egg yolk, the total apoprotein mixture (i.e. the 'apovitellenins') from the high-lipid, low-density lipoprotein (density 0.97 g/ml) of the yolk from hen's eggs has been isolated in a soluble form. By gel-filtration chromatography in 6M urea the mixture has been separated into several fractions from which three new low-molecular-weight proteins (I, Ia, and II), making up about 30% of the total, have been isolated. The most plentiful of these (I) consists of stable aggregates with several identical subunits each of molecular weight about 10 000. This protein is analogous to the principal protein from the corresponding lipoprotein of emu's egg yolk, i.e. emu's apovitellenin I. Hen's apovitellenin I has a slightly different amino acid composition from that of the emu; notably it contains a sulphydryl group. The hen's protein also forms more stable aggregates that are dissociated by detergent and by guanidine hydrochloride but are stable in urea. The molecular weight of Ia is similar to that of I and the amino acid composition is the same, with the exception that Ia has a higher proportion of amide groups. It aggregates less readily than I under the same conditions. The third new protein (II, 'hens's apovitellenin II') has a molecular weight of about 20 000. It has no tyrosine or methionine residues, but contains glucosamine and has several disulphide groups. It has been isolated in very small amount only.     

New subtype of salmonid alphavirus (SAV), Togaviridae, from Atlantic salmon Salmo salar and rainbow trout Oncorhynchus mykiss in Norway

In Europe, 2 closely related alphaviruses (Togaviridae) are regarded as the causative agents of sleeping disease (SD) and salmon pancreas disease (SPD): SD virus (SDV) has been isolated from rainbow trout Oncorhynchus mykiss in France and the UK, while SPD virus (SPDV) has been isolated from salmon Salmo salar in Ireland and the UK. Farmed salmonids in western Norway also suffer from a disease called pancreas disease (PD), and this disease is also believed to be caused by an alphavirus. However, this virus has not yet been characterised at the molecular level. We have cultured a Norwegian salmonid alphavirus from moribund fishes diagnosed with cardiac myopathy syndrome (CMS) and fishes diagnosed with PD. The virus has also been found in salmon suffering from haemorrhagic smolt syndrome in the fresh water phase. The genomic organisation of the Norwegian salmonid alphavirus is identical to that in SPDV and SDV, and the nucleotide sequence similarity to the other 2 alphaviruses is 91.6 and 92.9%, respectively. Based on the pathological changes, host species and the nucleotide sequence, we suggest naming this virus Norwegian salmonid alphavirus (NSAV). Together with SPDV and SDV it constitutes a third subtype of salmonid alphavirus (SAV) species within the genus Alphavirus, family Togaviridae.     

Two proteins purified from lobster nerve extract; isolation and physicochemical characterization

1. A protein component, fraction B, of lobster nerve extracts has been isolated and purified by differential ultracentrifugation and precipitation with zinc acetate. 2. Physicochemical data obtained from this protein and from fraction C are summarized. 3. Fraction B is present in lobster nerve extracts in higher concentration (relative to fraction A) than in blood. 4. A second component, fraction C, of sedimentation constant S(20) (o) = 13.2 has been isolated from lobster nerve extracts.     

Differences in Conformational Behavior of ATA and TAT Sequences in Single Strand DNA Trimer

Abstract

The conformational behavior of single strand (ss) TAT and ATA trimers of DNA have been studied by computational chemistry tools including CICADA software interfaced with AMBER molecular mechanics and dynamics. The Single-Coordinate-Driving (SCD) method has been used in conjunction with molecular dynamics simulated annealing. It has been revealed that the conformational flexibility of each sequence differs substantially from the other one. Four common conformational families have been found for both trimers. These are: helical, reverse-stacked (base 3), half-stacked (base 3), reverse-stacked (base 1). However, the energies of conformers representing the families are different for both the studied systems. An additional conformational family, bulged, has been found for ss(ATA), while ss(TAT) has been found also in half-stacked (base 1) conformation. In general, ss(TAT) exhibits a higher number of low energy conformations while ss(ATA) shows one interesting low energy conformational interconversion between reverse-stacked (A3) family and half-stacked (A3) family. The high conformational variability of the trimers has been confirmed by flexibility analysis and by molecular dynamics simulations, which have also shown the conformational stability of single conformational families. It has been concluded that the methodology used is able to provide a very detailed picture of the conformational space of these molecules.     

New antibiotic resistance Loci in the ribosomal region of yeast mitochondrial DNA

A large number of mitochondrial antibiotic-resistant mutants have been isolated following mutagenesis with manganese. These include several different phenotypic classes of mutants, as distinguished by cross-resistance patterns, that have been found to be allelic at cap1 or ery1; some have been found to be heteroallelic.--Seven chloramphenicol-resistant mutants have been identified that are nonallelic by recombination tests with the three loci (cap1, spi1 and ery1) previously identified in the ribosomal region. Four of these are allelic with each other and define a new locus, cap3; two others are allelic and define another new locus, cap2; the seventh maps at yet a different locus, cap4. One new spiramycin-resistant mutant has been identified that defines still another new locus, spi2. A variety of genetic techniques have been used to map these loci within the ribosomal region of the mitochondrial genome.-Manganese has been shown to be effective in inducing the mutation from omega(-) to omega(n) in many mutants that experience a simultaneous mutation at the closely linked cap1 locus. The omega(n) mutation has also been described in the cap4 mutant, and this locus has been shown to be more closely linked to omega than cap1 is to omega.     

Time-resolved fluorescence emission and excitation spectroscopy of d(TA) and d(AT) using synchrotron radiation

The photophysics of the sequence isomers d(TA) and d(AT) has been investigated at room temperature in 5 x 10(-5) M neutral aqueous solution using pulsed ultraviolet excitation from the ACO synchrotron and detection by time correlation or gated single-photon counting. Decay profiles of the emissions at 350, 400 and 460 have been analyzed both independently and globally by reiterative non-linear least-squares fitting to models of two and three independently emitting species. No evidence has been observed for excited-state reaction. Time-windowed spectra, both emission and excitation, have been collected for three time windows and have been deconvoluted to give time-resolved spectra using the lifetimes resulting from the decay analyses. Spectra are separated into two classes, with picosecond and nanosecond lifetimes, respectively. The picosecond spectra have the emission and excitation spectral characteristics of mixed monomer (A and T) fluorescences and are assigned as originating from the unstacked fractions of d(TA) and d(AT). The nanosecond emission spectra from d(TA) and d(AT) are both two-component, with lambda max approximately 350 and approximately 425 nm and lifetimes of 2.3 and 6.1 ns, respectively. The time-resolved excitation spectra for the nanosecond emissions are quite different from the isotropic absorption spectra of d(TA) and d(AT) but correlate with the anisotropic absorption for out-of-plane transitions between stacked bases of co-crystals of 9-methyladenine and 1-methylthymine reported by Stewart and Davidson. The nanosecond spectra thus represent the direct excitation and emission of stacked pairs of bases. These results provide no evidence for energy transfer and are probably related to sequence-specific photo-adduct formation.     

Purification and molecular characterization of alcohol dehydrogenase from Drosophila hydei: Conservation in the biochemical features of the enzyme in several species of Drosophila

Alcohol dehydrogenase (ADH) has been purified from Drosophila hydei. Biochemical investigations show that the native enzyme is a dimer consisting of two identical subunits with molecular weight 27,000. The pH optimum values of pure enzyme preparations are 7.9 and 9.4. The pI values are 8.83 and 8.41. Substrate specificities have been characterized. Km(app) values are lowest for propan-2-ol and butan-2-ol and Vmax(app) values are highest for these two substrates. The amino acid composition has been determined. Peptide mapping experiments performed after trypsin digestion of the enzyme allow the identification of 24 peptides. Peptides comprising 64% of the amino acid residues have also been purified by high-performance liquid chromatography (HPLC), and their N-terminal residues and amino acid composition determined. Results are compared with the amino acid sequence of ADH from D. melanogaster Adhs [Thatcher, D. R. (1980). Biochem. J. 187:875]. When data on the biochemical and structural characterization of ADH from D. hydei are compared with data from other species of Drosophila, clear homologies are observed.     

The primary structure of ribosomal protein L2 from Bacillus stearothermophilus

The complete amino acid sequence of ribosomal protein L2 from the moderate thermophile Bacillus stearothermophilus has been determined. This has been achieved by the sequence analysis of peptides derived by enzymatic digestion with Staphylococcus aureus protease, trypsin and chymotrypsin, as well as by chemical cleavage with o-iodosobenzoic acid. The protein contains 275 amino acid residues and has a calculated molecular mass of 30201 Da. Comparison of this sequence with sequences of the corresponding proteins from Escherichia coli and from spinach and tobacco chloroplasts reveals that 60% of the residues of protein L2 from B. stearothermophilus are identical to those of the protein from E. coli and 45% are identical to those found in the two chloroplast proteins. There are extended regions of totally conserved sequence at positions 54-58 (GGGHK), 81-86 (EYDPNR), and 224-230 (MNPVDHP) in all four proteins.     

Comparative risk assessment of secondary cancer incidence after treatment of Hodgkin's disease with photon and proton radiation

Probabilities for secondary cancer incidence have been estimated for a patient with Hodgkin's disease for whom treatment has been planned with different radiation modalities using photons and protons. The ICRP calculation scheme has been used to calculate cancer incidence from dose distributions. For this purpose, target volumes as well as critical structures have been outlined in the CT set of a patient with Hodgkin's disease. Dose distributions have been calculated using conventional as well as intensity-modulated treatment techniques using photon and proton radiation. The cancer incidence has been derived from the mean doses for each organ. The results of this work are: (a) Intensity-modulated treatment of Hodgkin's disease using nine photon fields (15 MV) results in nearly the same cancer incidence as treating with two opposed photon fields (6 MV). (b) Intensity-modulated treatment using nine proton fields (maximum energy 177.25 MeV) results in nearly the same cancer incidence as treating with one proton field (160 MeV). (c) Irradiation with protons using the spot scanning technique decreases the avoidable cancer incidence compared to photon treatment by a factor of about two. This result is independent of the number of beams used. Our work suggests that there are radiotherapy indications in which intensity-modulated treatments will result in little or no reduction of cancer incidence compared to conventional treatments. However, proton treatment can result in a lower cancer incidence than photon treatment.     

In-Plane and Out-of-Plane Plasmons in Random Silver Nanoisland Films

Effective permittivity of closely spaced random nanoparticles supported by a substrate has been calculated using a modified Yamaguchi’s model (MYM) which involves the exact expression of a local field outside a metal nanoparticle (NP) along with the effective-medium approach. Pulsed laser deposition has been used to deposit silver nanoisland films on SiO₂ substrates. In-plane and out-of-plane plasmonic responses have been calculated using MYM for various filling fractions and the results are compared with those obtained from spectroscopic ellipsometry. Distinct features of out-of-plane and in-plane plasmons are observed with an spectroscopic ellipsometer and their behavior is supported by the present theoretical investigation. The comparison of the effective dielectric constants of the films obtained from ellipsometry data with those calculated using MYM shows uniaxial optical anisotropy in our case. The calculated morphological parameters (filling fraction, aspect ratio, and average particle size) using MYM are also found to be consistent with those obtained from FESEM images.     

Degradation of polysaccharides and lignin in wood ozonation

Ozonation has been considered as a method for the pretreatment of plant biomass to obtain cellulose and monosaccharides. Ozone consumption by aspen wood with various moisture contents has been investigated. We have considered the gradual transformation of the substrate: wood to ozonated wood to cellulose-containing product (CP) to holocelluloze (HC) and to cellulose. Yields of ozonated wood (OW), the (CP), water-soluble ozonation products, HC, and cellulose have been determined. The lignin content in the CP has been estimated. Both HC and cellulose samples have been studied by IR spectroscopy. The degree of polymerization and molecular mass distribution of cellulose obtained from ozonated wood have been determined. It has been shown that wood destruction by ozone is accompanied by degradation of lignin, hemicelluloses, and cellulose.It has been found that physicochemical properties of cellulose obtained from ozonated wood can be regulated by the variation of the initial moisture content in the substrate. Both molecular ozone and radical species, which are generated in the course of ozone reactions with water present in the substrate structure, participate in wood destruction.