Planar aromaticity of <Emphasis Type="Italic">D</Emphasis><Subscript><Emphasis Type="Italic">N</Emphasis><Emphasis Type="Italic">h</Emphasis></Subscript>-symmetrical systems as a perturbed two-dimensional (2D) rigid rotor

Energy levels for D _{N h} -symmetrical cyclic polyenes with planar aromaticity were obtained using two-dimensional (2D) rigid rotor as the zeroth approximation. The addition of nuclei was simulated by the cosine-type potential and treated at the first-order perturbation theory. The result is qualitatively equivalent to that obtained using Hückel’s molecular orbital theory. As an addition, the energetic shift between σ and π orbitals is obtained using the model of electron oscillating around the center of a positively charged ring.     

Theoretical assessment of oscillations in the concentrations of P<Stack><Subscript>700</Subscript><Superscript>+</Superscript></Stack> and intermediates of the Calvin-Benson cycle

A theoretically obtained oscillatory mode of photosynthesis caused by long-wave illumination is discussed. Periodical variations in the operation of photosystem (PS) I, the electron transport chain, and the Calvin-Benson cycle take place in this mode. The changes in PS II operation are not repetitive. Damped oscillations of P₇₀₀⁺ concentration and CO₂ assimilation rate are observed in the theoretical curves. The results of modeling are quite consistent with the P₇₀₀⁺ kinetics obtained earlier by measuring the induction of the PS I EPR signal in leaves at different temperatures.     

Estimation de la distensibilité aortique à partir de séquences d’images de résonance magnétique « steady-state free-precession » et « contraste de phase »

Objective

To investigate the accuracy in the estimation of the aortic lumen area and distensibility obtained from Steady-State Free-Precession (SSFP) and Phase Contrast (PC) MR sequences.

Subjects and methods

Systolic and diastolic aortic lumen of the ascending and descending aorta of 50 subjects, collected with both acquisition sequences, were extracted using a 2D + t automated segmentation method.

Results

While the statistical study indicated very similar lumen areas for SSFP and PC data (slope = 1, r = 0.99), the corresponding distensibility values were less correlated (r = 0.54). Comparison between distensibility values in the ascending and descending aorta and study of these values with aging indicated a greater coherence with expected physiological behavior of the aorta when using SSFP images.

Discussion

Flow artifacts were more severe in PC images and could explain the better results obtained when using SSFP sequences.

Conclusion

A more accurate local assessment of the aortic stiffness is obtained from SSFP image sequences than from PC image sequences.     

Protoplast formation and regeneration in <Emphasis Type="Italic">Lactobacillus delbrueckii</Emphasis>

Method for production and regeneration of Lactobacillus delbrueckii protoplasts are described. The protoplasts were obtained by treatment with a mixture of lysozyme and mutanolysin in protoplast buffer at pH 6.5 with different osmotic stabilizers. The protoplasts were regenerated on deMan, Rogosa and Sharpe (MRS) with various osmotic stabilizers. Maximum protoplast formation was obtained in protoplast buffer with sucrose as an osmotic stabilizer using a combination of lysozyme (1 mg/ml) and mutanolysin (10 μg/ml). Maximum protoplast regeneration was obtained on MRS medium with sucrose (0.5 M) as an osmotic stabilizer. The regeneration medium was also applicable to other species of lactobacilli as well. This is, to our knowledge, the first report on protoplast formation and efficient regeneration in case of L. delbrueckii.     

Main trends in the genetic transformation of <Emphasis Type="Italic">Populus</Emphasis> species

The main advantages that could be obtained by poplar plantation production were described in this review. We also described the significance of poplars for industry and for solutions to ecological problems. Taking into consideration the results obtained by genetic engineering methods, we analyzed the trends in the improvement of the Populus phenotypes related to the resistance to biotic and abiotic stresses and herbicides, as well as to the modification of the wood quality (decreasing or modifing the lignin content), phytoremediation, plant growth acceleration, and changes in the plant morphology.     

Mutagenicity and antimutagenicity of <Emphasis Type="Italic">Croton cajucara</Emphasis>

Croton cajucara Benth. (‘sacaca’) is a tree of the Euphorbiaceae family, native to the Amazon region in northern Brazil, where it is widely used in the popular treatment of various diseases. Its active principle, the terpenoid trans-dehydrocrotonin, has been credited with a variety of medical properties, including antiulcer, antiinflammatory, antitumor, antimutagenic and hypoglycemic activity. In this investigation, possible mutagenic and antimutagenic effects were evaluated in treatments using methanol extract of this plant on Swiss Albino mice by examining their peripheral blood cells for micronuclei. In these tests, the material obtained by methanol extraction of C. cajucara tree bark was administered to the mice by gavage. None of the doses evaluated in this study presented mutagenicity. Analysis of the results obtained from studies evaluating antimutagenicity revealed protection against the chemotherapeutic agent cyclophosphamide for the two highest doses used.     

Construction of an Effective Protein Expression System Using the <Emphasis Type="Italic">tpl</Emphasis> Promoter in <Emphasis Type="Italic">Escherichia coli</Emphasis>

An effective protein expression system was constructed in Escherichia coli using the promoter of the tyrosine phenol-lyase (tpl) gene of Erwinia herbicola. This system involves a mutant form of the TyrR protein with an enhanced ability to activate tpl and the TutB protein with an ability to transport L-tyrosine (an inducer of Tpl). The highest expression level obtained for this system was more than twice that obtained for the tac system, although it was lower than the level obtained for the T7 system, as revealed with the lac-reporter assay and SDS-polyacrylamide gel electrophoresis.     

Gynogenesis in the vine cacti <Emphasis Type="Italic">Hylocereus</Emphasis> and <Emphasis Type="Italic">Selenicereus</Emphasis> (Cactaceae)

Gynogenesis was investigated on the allotetraploid Selenicereus megalanthus and the diploid Hylocereus polyrhizus and Hylocereus undatus vine cactus species. Unpollinated ovules from developing flower buds containing microspores at middle uninucleate developmental stage were cultured on MS basal medium containing 2,4-D/TDZ with different sucrose concentrations. Ovule size increased under dark culture conditions in all the three species and the level of response was species and sucrose concentration dependent. The best responses were achieved in the two S. megalanthus accessions, E-123 and J-80, at 0.18 and 0.26 M sucrose. Only ovule enlargement was obtained in H. undatus and both ovule enlargement and callus were obtained in H. polyrhizus. Development in both species ceased and embryoids were not formed. Plant regeneration was directly and indirectly obtained in both S. megalanthus accessions. Ploidy level was determined for a total of 29 S. megalanthus gynogenic plants using flow cytometry: 15 were found to be dihaploid (plants with the gametophytic chromosome number) and the other 14 were found to have higher ploidy levels. This is the first report of successful gynogenesis in Cactaceae. The dihaploids of S. megalanthus successfully produced by ovule culture techniques opens new perspectives in vine cacti breeding.     

Essential oil composition of <Emphasis Type="Italic">Taraxacum officinale</Emphasis>

The gas chromatography–mass spectrometry (GC–MS) analysis of essential oil obtained by hydrodistillation from the flower of Taraxacum officinale L. revealed the presence of 25 compounds with 1,3-dimethylbenzene, 1,2-dimethylbenzene, 1-ethyl-3-methylbenzene, heneicosane and tricosane as the main components.     

Plant regeneration from carrot (<Emphasis Type="Italic">Daucus carota</Emphasis> L.) anther culture derived embryos

The research concerned of the regeneration of plants from embryos obtained from anther cultures of seven carrot (Daucus carota L.) cultivars. The aim was to determine the influence of the regeneration medium on the efficiency of the regeneration process. The optimization of the adaptation of the obtained plants was also carried out. Embryogenesis occurred on four of the tested media: B5 and MS without hormones, MS with charcoal, and MS with 1 mg dm⁻³ BA and 0.001 mg dm⁻³ NAA. Embryos obtained from the anther cultures produced secondary embryos, from which the regenerations of plants was observed. Secondary embryos were formed most extensively on the B₅ medium without hormones. The efficiency of the regeneration process depended on the cultivar. Most of the secondary embryos were formed by androgenetic embryos of the cultivar ‘Feria F₁’. The highest number of plants (102) regenerated from one embryo during 12 weeks of culture was also obtained in case of the cultivar ‘Feria F₁’. Secondary embryogenesis and plant regeneration from embryos allow to omit the difficult stage of root induction applied when plants are regenerated form shoots' explants. This makes the plant regeneration process quicker and easier. The plants regenerated by the conversion of embryos are better adapted to the ex vitro conditions than those obtained in the two-stage organogenesis involving the regeneration of shoots and in second stage roots induction.     

Design of mutant variants of horse cytochrome <Emphasis Type="Italic">c</Emphasis> by analysis of informational structure method and testing its biological activity

Informational structure of cytochrome c was investigated using the ANIS method (Analysis of Informational Structure Method). Mutant variants of cytochrome c gene were constructed on the basis of data from the ANIS method. The mutations carry substitutions reducing electron-transport activity of cytochrome c in the mitochondrial respiratory chain. These mutant genes were obtained and expressed in the bacterial system. The biological activity of the obtained cytochrome c mutant variants interacting with complexes III and IV of the respiratory chain in the system of rat liver mitoplasts.     

Application of <Emphasis Type="Italic">gyrB</Emphasis> and <Emphasis Type="Italic">parE</Emphasis> sequence similarity analyses for differentiation of species within the genus <Emphasis Type="Italic">Geobacillus</Emphasis>

The primary structures of the genes encoding the β-subunits of a type II topoisomerase (gyrase, gyrB) and a type IV topoisomerase (parE) were determined for 15 strains of thermophilic bacteria of the genus Geobacillus. The obtained sequences were used for analysis of the phylogenetic similarity between members of this genus. Comparison of the phylogenetic trees of geobacilli constructed on the basis of the 16S rRNA, gyrB, and parE gene sequences demonstrated that the level of genetic distance between the sequences of the genes encoding the β-subunits of type II topoisomerases significantly exceeded the values obtained by comparative analysis of the 16S rRNA gene sequences of Geobacillus strains. It was shown that, unlike the 16S rRNA gene analysis, comparative analysis of the gyrB and parE gene sequences provided a more precise determination of the phylogenetic position of bacteria at the species level. The data obtained suggest the possibility of using the genes encoding the β-subunits of type II topoisomerases as phylogenetic markers for determination of the species structure of geobacilli.     

Effects of Different Geographical Aspects and Ontogenetic Variability on Total Hypericin Content of <i>Hypericum triquetrifolium</i> Turra. and <i>Hypericum scabrum</i> L.

The present study was conducted to determine the total hypericin contents of Hypericum triquetrifolium Turra. and Hypericum scabrum L. species which are naturally distributed in the flora of Siirt province, Turkey. Hypericin contents of Hypericum species grown in different geographical aspects (North, South, East, and West), and it was measured at different harvest times (full blooming and post blooming period). In the current study, it has been determined that total hypericin content varies considerably according to aspects, plant developmental stages (ontogenetic variance), and species. According to species x aspect interaction, the highest total hypericin content was recorded from the west aspect (3.13 mg/g) in Hypericum triquetrifolium, while, the lowest hypericin content was also obtained from the west aspect (1.22 mg/g) in Hypericum scabrum. When the highest total hypericin content was analyzed according to aspect x species x harvest time interaction, the highest total hypericin content was produced from Hypericum triquetrifolium at the harvest of west aspect with 5.28 mg/g, while the minimum amount of hypericin was obtained from the same aspect in Hypericum scabrum with 0.50 mg/g. In species x harvest time interaction, the highest total hypericin content was obtained from the full bloom (3.10 mg/g) harvest in Hypericum triquetrifolium, while the lowest hypericin was obtained from the full bloom (1.26 mg/g) harvest in Hypericum scabrum. The data suggest that the average total hypericin content was 2.26 mg/g in Hypericum triquetrifolium and 1.28 mg/g in Hypericum scabrum.     

Immunological and biological relationship among flagellin of <Emphasis Type="Italic">Pseudomonas aeruginosa,Burkholderia cepacia</Emphasis>, and <Emphasis Type="Italic">Stenotrophomonas maltophilia</Emphasis>

The flagellar protein (flagellin) was isolated and purified from strains of Pseudomonas aeruginosa, Burkholderia cepacia and Stenotrophomonas maltophilia. A significant difference was observed in the molecular weight of different flagellin preparations obtained from these bacterial isolates. Antiserum prepared against S. maltophilia flagellin did not react with flagellin of P. aeruginosa or/and B. cepacia on Immunoblot or in indirect ELISA. In addition the anti-flagellin did not agglutinate P. aeruginosa and B. cepacia. No inhibition of motility of P. aeruginosa and B. cepacia was observed in presence of antiserum; though the latter inhibited the motility of S. maltophilia. The results of the present study prove that no specific relationship existed among all the studied flagellar proteins obtained from closely related bacteria.     

Genetic transformation of the medicinal plant <Emphasis Type="Italic">Salvia miltiorrhiza</Emphasis> by <Emphasis Type="Italic">Agrobacterium tumefaciens</Emphasis>-mediated method

A high-frequency and simple procedure for Agrobacterium tumefaciens-mediated genetic transformation of the medicinal plant Salvia miltiorrhiza was developed. Leaf discs were pre-cultured on MS medium supplemented with 6.6 μmol l⁻¹ BAP and 0.5 μmol l⁻¹ NAA for one day, then co-cultured with A. tumefaciens strain EHA105 harboring the plasmid pCAMBIA 2301 for three days on the same medium. Regenerated buds were obtained on selection medium (co-culture medium supplemented with 60 mg l⁻¹ kanamycin and 200 mg l⁻¹ cefotaxime) after two cycles’ culture of 10 days each and then transferred to fresh MS medium with 60 mg l⁻¹ kanamycin for rooting. Fifteen days later, the rooted plantlets were obtained and then successfully transplanted to soil. The transgenic nature of the regenerated plants was confirmed by PCR, Southern hybridization analysis and GUS histochemical assay. Averagely, 1.1 independent verified transgenics per explant plated were obtained through this protocol. Adopting this procedure, positive transformed plants could be obtained within 2–3 months from mature seeds germination to transplant to soil, and more than 1,000 transgenic plants with several engineered constructs encoding different genes of interest were produced in our lab in the past two years.     

Genome-wide analysis of across herd <Emphasis Type="Italic">F</Emphasis> <Subscript>st</Subscript> Heterogeneity in holsteinized cattle

To form a reference population necessary for genomic selection of dairy cattle, it is important to acquire information on the genetic diversity of the base population. Our report is the first among the studies on breeding of farm animals to implement Wright’s F-statistics for this purpose. Genotyping of animals was performed using BovineSNP50 chip. In total, we genotyped 499 heifers from 13 breeding farms in the Leningrad region. We calculated Weir and Cockerham’s F_st estimate for all pairwise combinations of herds from breeding farms and the values obtained were in the range of 0.016–0.115 with the mean of 0.076 ± 0.002. Theoretical F_st values for the same pairwise combinations of herds were calculated using the ADMIXTURE program. These values were significantly (P < 0.05) higher than Weir and Cockerham’s F_st estimates and fell in the range of 0.063–0.136 with the mean of 0.100 ± 0.001. We discuss the reasons for this discrepancy between the two sets of F_st data. The obtained F_st values were used to identify reliable molecular-genetical differences between the herds. The ADMIXTURE program breaks the pool of 476 heifers into 16 subpopulations, the number of which is close to the number of herds used in the experiment. Results of the comparison between F_st values obtained using SNP markers with published data obtained on microsatellites are in support of the common opinion that microsatellite analysis results in underestimation of F_st values. On the whole, the obtained across-herd F_st values are in the range Fst data reported for cattle breeds. Results of comparison of F_st values with the data on the origin of bulls imported from different countries lead to the conclusion on the expediency of the use of F_st data to assess heterogeneity of the herds. Thus, we have demonstrated that use of F_st data provides the means to assess genetic diversity of cattle herds and is a necessary step in the formation of a reference population for dairy cattle.     

Effect of alkali treatment time and extraction time on agar from <Emphasis Type="Italic">Gracilaria vermiculophylla</Emphasis>

The effects of alkali treatment time and extraction time of native agar and alkali treated agar obtained from Gracilaria vermiculophylla were studied. The response characteristics were mainly agar yield and gel strength. Alkali treatment was carried out at 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0 h. Agar yield and gel strength decreased with the increase in the time of the alkali treatment. The highest yield (15.3%) and highest gel strength (1,064 g cm⁻²) were obtained at 0.5 h, and therefore this time was used for the next experiment. The extraction of both native and alkali treated agars was carried out at 1.5, 2.0, 2.5, and 3.0 h. The best extraction time for alkali treated agar was 1.5 h, and for native agar 2.5 h. The alkali treated agar obtained with the different alkali treatment and extraction times showed higher melting (92.4–99.7°C) and gelling (35.7–39.6°C) temperatures. Native agar was lower in melting (60.2–64.1°C) and gelling (20.4–23.4°C) temperatures. The 3,6-anhydrogalactose content decreased with increasing alkali treatment time, with the opposite effect during the extraction of native and alkali treated agars.     

Partial characterization and antimicrobial activity of peptides from <Emphasis Type="Italic">Amburana cearensis</Emphasis> seeds against phytopathogenic fungi and yeasts

The aim of this work was to study the antifungal action of a protein and peptide-rich fraction from Amburana cearensis seeds. Initially, proteins were extracted from seed flour in phosphate buffer and re-extracted with 1 M lithium chloride. The products obtained from both extractions were precipitated with ammonium sulfate at 70% saturation, and the precipitates were re-suspended in distilled water, heated at 80°C for 15 min and clarified by centrifugation at 12,000×g. The obtained fractions from both extractions were dialyzed, recovered by lyophilization and visualized in Tris–Tricine/SDS gel electrophoresis. The fractions obtained were rich in proteins of low molecular weight and were submitted to antifungal assays. Fraction S4 (extraction with phosphate buffer) inhibited the fungi, Colletotrichum lindemuthianum, Fusarium oxysporum, Fusarium solani, Candida albicans and Saccharomyces cerevisiae. Fractions P2 (re-extraction with lithium chloride) had a low or non-inhibitory effect on the fungi tested.     

Computational synthesis of hydrogenated fullerenes from C<Subscript>60</Subscript> to C<Subscript>60</Subscript>H<Subscript>60</Subscript>

Hydrogenation from C₆₀ to C₆₀H₆₀ was studied by an unrestricted broken spin symmetry Hartree–Fock approach implemented in semiempirical codes based on the AM1 technique. The calculations focused on the successive addition of hydrogen molecules to the fullerene cage following the identification of the cage target atoms by calculating the highest atomic chemical susceptibility at each step. The results obtained are analyzed from energy, symmetry, and composition perspectives.     

Resistance of Human Erythrocyte Membranes to Triton X-100 and C<Subscript>12</Subscript>E<Subscript>8</Subscript>

Lipid rafts are microdomains enriched in cholesterol and sphingolipids that contain specific membrane proteins. The resistance of domains to extraction by nonionic detergents at 4°C is the commonly used method to characterize these structures that are operationally defined as detergent-resistant membranes (DRMs). Because the selectivity of different detergents in defining membrane rafts has been questioned, we have compared DRMs from human erythrocytes prepared with two detergents: Triton X-100 and C₁₂E₈. The DRMs obtained presented a cholesterol/protein mass ratio three times higher than in the whole membrane. Flotillin-2 was revealed in trace amounts in DRMs obtained with C₁₂E₈, but it was almost completely confined within the DRM fraction with Triton X-100. Differently, stomatin was found distributed in DRM and non-DRM fractions for both detergents. We have also measured the order parameter (S) of nitroxide spin labels inserted into DRMs by means of electron paramagnetic resonance. The 5- and 16-stearic acid spin label revealed significantly higher S values for DRMs obtained with either Triton X-100 or C₁₂E₈ in comparison to intact cells, while the difference in the S values between Triton X-100 and C₁₂E₈ DRMs was not statistically significant. Our results suggest that although the acyl chain packing is similar in DRMs prepared with either Triton X-100 or C₁₂E₈ detergent, protein content is dissimilar, with flotillin-2 being selectively enriched in Triton X-100 DRMs.