Forgot your password?
New user?
New Window Opens on the Secret Life of Microbes: Scientists Develop First Microbial Profiles of Ecosystems
CAS announces the release of SciFinder Scholar for Mac OS X
Press Releases
Press Releases
| Check out our New Publishers' Select for Free Articles |
Applied Biochemistry and Microbiology (v.42, #5)
Heterothallism of mucoraceous fungi: A review of biological implications and uses in biotechnology by E. P. Feofilova (pp. 439-454).
The phenomenon of heterothallism in filamentous fungi is reviewed, with emphasis on the discussion of hormonal regulation of heterothallic strains of mucoraceous fungi. This process is viewed from the standpoint of current understanding that fungal cells communicate with each other using a special “language,” i.e., signaling chemicals (hormones or pheromones). Physiological and biochemical criteria of distinguishing between heterosexual strains, which make it possible to draw analogies with higher eukaryotes, are set forth for the first time, based on experimental data obtained with Blakeslea trispora. The synthetic pathway to trisporic acids (a zygogenic sex hormone of Mucorales), their relation to carotenoids, and biological functions are described. The similarity (both structural and functional) between fungal, plant, and animal hormones is another topic dealt with. Current understanding of the role of terpenoids in the evolution of sexual communication and transduction is presented with an excursion into microbial endocrinology, a novel field of research in biology. The concluding part of the review analyzes the data on biotechnological implications of the phenomenon of heterothallism. Specifically, it may be used to obtain a series of isoprenoid compounds, such as β-carotene and lycopene (which exhibit pronounced antioxidant activity), as well as sterols and trisporic acids.
Real-time PCR: A review of approaches to data analysis by D. V. Rebrikov; D. Yu. Trofimov (pp. 455-463).
The registration of the accumulation of polymerase chain reaction (PCR) products in the course of amplification (real-time PCR) requires specific equipment, i.e., detecting amplifiers capable of recording the level of fluorescence in the reaction tube during amplicon formation. When the time of the reaction is complete, researchers are able to obtain DNA accumulation graphs. This review discusses the most promising algorithms of the analysis of real-time PCR curves and possible errors, caused by the software used or by operators’ mistakes. The data included will assist researchers in understanding the features of a method to obtain more reliable results.
A regulatory protein isolated from cattle milk by P. A. Nazarova; M. S. Krasnov; V. P. Yamskova; I. A. Yamskov (pp. 464-467).
A regulatory protein displaying biological activity at ultralow doses was identified in cow’s milk. The isoelectric point for this protein falls into the pH range of 4.48–5.59, and the molecular weight does not exceed 10 kDa. A study of the secondary structure detected the predominant presence of β-structures, especially antiparallel, in the molecule of this regulatory protein as well as the regions described in terms of a statistical globule. It was demonstrated that this protein is located extracellularly in the epithelium of mammary ducts, and that this regulatory protein is present in an active form in whole milk; however, it was detectable neither in dry milk nor in infant formula. The results obtained suggest that the milk regulatory protein characterized in this work was identical to low-molecular-weight serum glycoprotein, one of the proteins studied earlier, displaying biological activity at ultralow doses.
Isolation and study of active ATP-dependent phosphofructokinase from apple fruits Pyrus domestica Borkh by S. G. Gyulakhmedov; Y. A. Omarov; Z. M. Mamedov; A. A. Kuliev (pp. 468-471).
The activity of ATP-dependent phosphofructokinase (PFK) from subepidermal tissue of apple fruits was studied. The enzyme extracted under optimal conditions was stable for 14 h at room temperature. The enzyme was partially purified by ammonium sulfate fractionation and dialysis. PFK from apple fruits was found to be ATP-, UTP-, and CTP-specific. It was inhibited by PEP, Gly-2-P, Gly-1,3-DP, and ADP. The effect of the listed inhibitors was diminished by the presence of phosphate. The activity of PFK was stimulated by magnesium cations. The activity of the enzyme in fruits of an Antonovka cultivar was higher than in the Simirenko rennet cultivar by a factor of 1.3.
Range of substrates and steroid bioconversion reactions performed by recombinant microorganisms Saccharomyces cerevisiae and Yarrowia lipolytica expressing cytochrome P450c17 by V. M. Shkumatov; N. S. Frolova; E. V. Rudaya; Ya. V. Faletrov; S. Mauersberger; G. Barth (pp. 472-478).
The relationship between 17α-hydroxylation and 20-oxidation-reduction of progesterone and some of its derivatives was studied in yeast strains Saccharomyces cerevisiae YEp51α, Yarrowia lipolytica E129A15, and expressing cytochrome P450c17. The key metabolites were found to be 17α-hydroxyprogester-one and 17α,20(α,β)-dihydroxypregn-4-ene-3-ones. The bioconversion pathways of pregn-4-ene-20(α,β)-ol-3-ones were determined. They included cycles of 20-oxidation, 17α-hydroxylation, and stereospecific 20-reduction. The efficiency and kinetic parameters of steroid bioconversion by the recombinant strains were determined. The role of yeast analogs of mammalian steroid dehydrogenases is discussed. It was found that any of the desired derivatives, 17α-hydroxyprogesterone or progesterone 17α,20(α,β)-diols, could be obtained from progesterone. Cholesterol bioconversion yields important metabolites: steroid hormones, the vitamin-D group, and bile acids [1, 2]. Attention to various cytochrome-P450 species participating in the biosynthesis of mammalian steroid hormones is caused by two circumstances: (1) the necessity of detecting structural-function abnorm alities of some of the enzymes of steroid-synthesis that cause human diseases, and (2) the potential of regio-and stereospecific cytochrome P450 species of mammals in chemoenzymatic synthesis of pharmacologically valuable steroids. Concerning the second line of inquiry, the development of transgenic Saccharomyces cerevisiae yeast for the complete synthesis of cortisol by additional expression and elimination of a total of 13 genes was reported [3]. To increase the yield of the target compound, the genes for enzymes performing undesirable steroid modifications were inactivated. These modifications included esterification of pregnenolone [4] and 20α-reduction of 17α-hydroxyprogesterone [5]. A search for analogs of mammalian 20α-hydroxysteroid dehydrogenase (20α-HSD) in the Saccharomyces cerevisiae genome revealed two candidate proteins: Ypr1p (yeast aldo-keto reductase) and Gcy1p (yeast galactose-inducible crystallin-like protein) [3]. Indeed, it was formerly shown that expression of cytochrome P450 from bovine adrenal cortex, performing 17α-hydroxylation and the C17,20-lyase reaction (P450c17) in S. cerevisiae under the control of the GAL10-promoter with the presence of D-galactose as an inducer, was accompanied by the sequential conversion of progesterone to 17α-hydroxyprogesterone and 17α,20(α,β)-dihydroxypregn-4-ene-3-one with a high yield [5].
Biotransformation of cortexolone to hydrocortisone by molds using a rapid color-development assay by J. Manosroi; Y. Chisti; A. Manosroi (pp. 479-483).
The capacity of 22 molds for 11β-hydroxylation of cortexolone (Reichstein’s compound S) to hydrocortisone were assessed. The biotransformation capacity was compared for solid-state and submerged monocultures of molds that were otherwise under identical conditions. Thin-layer chromatography and a novel rapid color-development assay were used to qualitatively establish the ability of fungi to convert cortexolone to hydrocortisone. These assays were validated and supplemented with data from high-performance liquid chromatography to obtain quantitative information on biotransformation. Nearly all the fungi consumed a significant fraction of the cortexolone fed, but only four of them (i.e., two isolates of Cunninghamella blakesleeana, C. echinulata, and Curvularia lunata) yielded measurable quantities of hydrocortisone. Submerged cultures generally gave a significantly greater yield of hydrocortisone compared to equivalent solid-state cultures.
Distribution of intracellular fucoidan hydrolases among marine bacteria of the family Flavobacteriaceae by A. M. Urvantseva; I. Yu. Bakunina; O. I. Nedashkovskaya; S. B. Kim; T. N. Zvyagintseva (pp. 484-491).
A search for fucoidan-degrading enzymes and other O-glycosylhydrolases has been performed among 51 strains of marine bacteria of the family Flavobacteriaceae isolated from red, green, and brown algae, as well as from the sea urchin Strongylocentrotus intermedius and the holothurian Apostichopus japonicus. Over 40% of the studied strains synthesized fucoidanases. The marine bacteria Mesonia algae KMM 3909T (an isolate from green alga Acrosiphonia sonderi), as well as Maribacter sp. KMM 6211 and Gramella sp. KMM 6054 (associants of the sea urchin S. intermedius), were the best producers of fucoidanases. Xylose effectively induced the biosynthesis of fucoidanases in these strains. None of the 15 strains of marine bacteria belonging to the genus Arenibacter produced polysaccharide hydrolases.
Isolation and identification of new nisin-producing Lactococcus lactis subsp. lactis from milk by L. G. Stoyanova; T. D. Sul’timova; S. G. Botina; A. I. Netrusov (pp. 492-499).
A method for isolating active nisin-producing strains of mesophilic lactococci was developed. Overall, 55 strains of mesophilic lactic acid bacteria were isolated from fresh cow’s milk obtained from milk farms in various regions throughout Russia; of them, 36 displayed nisin-synthesizing activity. The three most active strains were studied according to morphological, cultural, physiological, and biochemical characteristics and identified as Lactococcus lactis subsp. lactis. The species attribution of the strains studied was confirmed by the similarity of the nucleotide sequences of the 16S rRNA gene. The nucleotide sequences of the 16S rRNA genes were deposited with the GenBank under accession numbers DQ255951–DQ255954. The distinctions between these strains in physiological and biochemical characteristics and the ranges of their bactericide action on the microorganisms capable of developing in agricultural materials and food products were determined. The isolated strains displayed considerably wider ranges of action, which differed from the nisin-producing strain MGU and the commercial nisin preparation (Nisaplin), used as a biological preserving agent.
Effect of silicone oil on gibberellic acid production by Gibberella fujikuroi and Aspergillus niger by S. Ates; S. Ozenir; M. Gökdere (pp. 500-501).
The effect of silicone oil on gibberellic acid production was investigated using Gibberella fujikuroi and Aspergillus niger fungi. Silicone oil was used as an oxygen vector in the gibberellic acid production process. When silicone oil was used, the concentration of gibberellic acid increased 4.6 and 6.7 times with respect to the control run having A. niger and G. fujikuroi microorganisms, respectively.
Interaction of proteinases secreted by the fungal plant pathogen Rhizoctonia solani with natural proteinase inhibitors produced by plants by E. L. Gvozdeva; A. V. Volotskaya; A. V. Sof’in; N. N. Kudryavtseva; T. A. Revina; T. A. Valueva (pp. 502-507).
The fungal plant pathogen Rhizoctonia solani Kuhn. grown in a medium containing thermostable potato tuber proteins produced proteinases active at moderately alkaline pH values. Electrophoretic analysis in polyacrylamide gel with SDS and copolymerized gelatin showed that the extracellular proteinase complex contained four components that differed in molecular weight. Studies on the action of the exoenzymes on various synthetic substrates indicated that the culture liquid of R. solani contained mainly trypsin-like proteinases. The exoproteinase activity was virtually completely suppressed by trypsin inhibitor proteins isolated from potato tubers and seeds of various legume species. The results suggest that the extracellular proteinases produced by R. solani play a significant role in attacking plant tissue, and natural inhibitors contribute to the protection of Solanaceae and Leguminosae from this fungal pathogen.
Depolymerization of legume seed galactomannan by Celloviridin G20x by A. V. Ilyina; N. M. Mestechkina; V. D. Shcherbukhin; V. P. Varlamov (pp. 508-513).
The depolymerization of legume galactomannans by the commercial preparation Celloviridin G20x was studied with the aim of obtaining macromolecular fragments of a constant composition. Four galactomannans, representative of the entire range of monomer ratios characteristic of this class of phytopolysaccharides, were hydrolyzed. The galactomannans were isolated from oriental goat’s rue (Galega orientalis Lam., Man: Gal 1.1), guar (Cyamopsis tetragonoloba L., Man: Gal 1.6), honeylocust (Gleditsia triacanthos f. inermis L., Man: Gal 2.4), and sophora (Styphnolobium japonicum (L.) Schott., Man: Gal 5.1). Fragments with a monomer ratio close to that in the original polysaccharides were obtained with a high yield (75–80%). The degree of substitution of the 1,4-β-D-mannopyranose chain at position C-6 with α-galactose residues influenced the molecular weight of the final reaction product.
Oak wood hemicelluloses extracted with aqueous-alcoholic media by A. F. Pisarnitskii; T. Yu. Rubeniya; A. O. Rutitskii (pp. 514-518).
Hemicellulose fractions were isolated from oak wood ethanol extracts (40–90%). To determine the composition of these fractions, they were hydrolyzed and the hydrolysis products in the form of trimethylsilyl derivatives were analyzed by GLC/MS. Depending on the content of the ethanol, hemicelluloses of a different composition were extracted from wood. In alcohols that were kept in oak wood, intended for manufacturing brandy and whisky, the content of the hemicelluloses increased depending on the duration of storage. It is assumed that this makes drinks more full-bodied and makes them softer.
Optimization of the protocol for constructing transgenic plants of the cabbage Brassica oleracea var. capitata by T. N. Gribova; A. M. Kamionskaya; K. G. Skryabin (pp. 519-524).
The strain Agrobacterium tumefaciens GV3101, which contains the pBar vector carrying the phosphinothricin acetyltransferase gene (bar) under the control of the 35SCMoV promoter and NOS 3′ terminator, was used for genetic transformation of four cabbage lines, Ges-3, Drv-2, Zmu 7, and Meg 2. The effect of different concentrations and combinations of phytohormones was studied, which allowed for choosing the cultivation conditions that provided a 63–87% regeneration efficiency. It was demonstrated that concerted action by natural and synthetic cytokinins is necessary for the lines studied. Overall, 26 transgenic plants were obtained using the optimized protocol for agrobacterial transformation. The transgenic nature of these plants was confirmed by PCR and dot-blot hybridization.
An electrochemical method for measuring metabolic activity and counting cells by B. A. Kuznetsov; M. T. Khlupova; S. V. Shleev; A. S. Kaprel’yants; A. I. Yaropolov (pp. 525-533).
An express electrochemical method for determining the metabolic activity of live cells based on the possibility of an electron exchange between an electrode and elements of the biological electron transfer chain in the presence of a mediator is proposed. This method is useful for studying any live cells (animal, plant, and microbial), including anaerobic, dormant, and spore cells. The sample preparation and measurement itself does not take more than 30 min. The detection limit in a volume of 15 ml amounts to 105 cells/ml. The applicability of the assessment method of the metabolic activity level during the transition of the bacteria Mycobacterium smegmatis into an uncultivable dormant state was demonstrated. This method is of special value for medicine and environmental control, detecting latent forms of pathogens. An optimal combination of the methods for the express analysis of latent pathogens is proposed.