Oxidation of hydroxylamine as an indicator reaction for the kinetic determination of copper and iron

The oxidation of hydroxylamine by hexacyanoferrate(III) is proposed as an indicator reaction for kinetic determining copper(II) traces (detection limit of 2 × 10-8 M). It is shown that iron(II) and total iron can be determined with a detection limit of 2 × 10-6 M using the oxidation of hydroxylamine by potassium bromate, catalyzed by Fe(II). The bromination of Methyl Orange catalyzed by bromide formed in the reduction of the bromate ion is proposed as an indicator reaction. © 1999 MAEe Cyrillic signK "Hayκa/Interperiodica"

Flow-injection determination of nickel with voltammetric detection by the catalytic hydrogen current

It is shown that the analytical signal in a flow-injection system with voltammetric detection can, in principle, be measured by the catalytic current of hydrogen liberation in solutions of nickel(II) cysteinates in the range 0.3-6.0 μg/mL Ni with a throughput capacity of 25 samples/h. © 1996 MAEe Cyrillic sign;K Hayκa/Interperiodica Publishing

Spin-other-orbit operator in the tensorial form of second quantization

The tensorial form of the spin-other-orbit interaction operator in the formalism of second quantization is presented. Such an expression is needed to calculate both diagonal and off-diagonal matrix elements according to an approach, based on a combination of second quantization in the coupled tensorial form, angular momentum theory in three spaces (orbital, spin and quasispin), and a generalized graphical technique. One of the basic features of this approach is the use of tables of standard quantities, without which the process of obtaining matrix elements of spin-other-orbit interaction operator between any electron configurations is much more complicated. Some special cases are shown for which the tensorial structure of the spin-other-orbit interaction operator reduces to an unusually simple form

Complex analysis of flax seeds composition for breeding programs

Single plant selection using complex of seed quality traits requires development and optimization of the methods, which allow qualitative and quantitative analysis applying minimum quantity of seeds. The proposed evaluation scheme of seed composition enables optimal use of seed material for individual plant analysis: oil percentage (Rushkovsky’s extraction method), fatty acid composition (vaporliquid chromatography), protein and ash content (dynamic thermogravimetry), elemental composition (electron probe X-ray fluorescence method). Reproducibility of analytical methods used was assessed by the coefficient of variation, the reproducibility index (ARI) and the convergence of data on seasonal cultivation

Identification and Intraspecific Typing of Plague Microbe Strains with Their Potential Virulence Determination Using PCR

Developed is the method of identification and intraspecific typing of plague microbe strains along with their potential virulence determination. Intraspecific differentiation and focal attribution of the examined plague microbe strains can be determined by monolocus VNTR-PCR, and main virulence determinants (chromosomal pigmentation region and calcium-dependence plasmid genes) - by multiplex PCR

The trait-specific collection of large-seeded sunflower at VIR: ba source for breeding cultivars and hybrids

Background. In recent years, an increase has been observed in the share of sunflower seeds in the confectionery and food industries. There are 30 cultivars and only 3 hybrids for confectionery use among 839 zoned sunflower cultivars and hybrids listed in the State Register for Selection Achievements Admitted for Usage in 2023. Thus, the development of source material for breeding large-seeded cultivars and hybrids remains a relevant task.Materials and methods. The studied material included 90 accessions selected for their large seed size from VIR’s sunflower collection. The following characters were assessed: 1000 seed weight, days from sprouting to maturation, plant height, head diameter, cypsela color and size, and resistance to downy mildew. DNA markers were used to identify accessions with the Rf1 gene and CMS.Results. Accessions k-2818 (Primorsky Territory), k-3633, k-3748, k-3782 (China), and k-3578 (Ukraine) were the best in 1000 seed weight. Russian cvs. ‘Alekseyevsky Krupnoplodny 2’ (k-3552), ‘Gyar-Gyar’ (k-1589), ‘SPK’ (k-3426), and ‘Lakomka’ (k-3526) confirmed their large seed size. The sterile type of cytoplasm was identified in 12 accessions. Fourteen accessions with fertile cytoplasm had diagnostic markers of the nuclear Rf1 gene.Conclusion. The large-seeded cultivars developed at VNIIMK, ‘SPK’, ‘Lakomka’, and k-3782 from China were the best not only in their large seed size but also in downy mildew resistance. As a result of long-term studies, a trait-specific collection was established for the large seed size trait. It included 90 accessions that can be used in the development of confectionery cultivars. Large-seeded sunflower accessions carrying the Rf1 gene were identified. Some of them became the ancestors of donor lines for both pollen fertility restoration genes and large seed size

Development of a Set of Primers for Drug-Resistance Genes Detection in the Agents of Dangerous Bacterial Infections as Exemplified by <I>Yersinia pestis</I>, <I>Vibrio cholerae</I>, <I>Escherichia coli</I> Strains

A set of primers for detection of genes encoding resistance to streptomycin ( strA, strB ), tetracyclin ( tetA, tetR ), chloramphenicol ( catА ), kanamycin ( npt , aphA ), vankomycin ( sanA ), polymyxin ( pmrD ) has been developed with the aim of rapid and effective detection of drug-resistant strains of dangerous bacterial infections agents. Efficacy of constructed primers has been confirmed against a panel of 40 Yersinia pestis, 49 Vibrio cholerae, and 2 Escherichia coli strains from the State collection of pathogenic bacteria of the RAPI “Microbe”. Drug-resistance genes ntp and catA have been detected in plague agent strains , strA, strB , npt , aphA , tetA and tetR - in cholera agent; strA , tetR , ntp and aphA - in pathogenic strain E. coli О157:H7. Determined is universal character of the designed primers for drug-resistance genes detection in these pathogenic bacteria species

Lines resistant to downy mildew in the sunflower genetic collection at VIR

Background. Downy mildew (DM) caused by the fungus Plasmopara halstedii (Farl) Berl. &amp; De Toni) is one of the most harmful diseases of sunflower (Helianthus annuus L.). Due to the pathogen’s attacks, annual seed harvest losses range between 30% and 70%. Lines resistant to new races of the pathogen should be obtained for the development of commercial sunflower hybrids.Materials and methods. Downy mildew resistance of 323 lines and 10 cultivars from the sunflower collection was assessed in the field at the Kuban Experiment Station of VIR in 2017–2018. Line VIR 845, susceptible during all years of observations, was used as a control. Resistance genes were identified by means of the molecular analysis using diagnostic markers of the Plarg, Pl6 and Pl8 genes that confer resistance to many known P. halstedii races.Results. The founder varieties of VIR’s lines were susceptible to a varying extent. Thirty-nine lines were resistant in 2016 and 2018; among those, 36 lines were susceptible in 2017. Presumably, a more virulent P. halstedii race became widespread in 2017, compared to the races that prevailed in 2016 and 2018, so the genes that determined resistance in 2016 and 2018 turned out to be ineffective. Lines ТА 716-18, VIR 768, and VIR 800, having originated from interspecific hybrids, exhibited absence of pathogenic damage during 3 years of the trials. Molecular markers of the Plarg, Pl6 and Pl8 genes were detected in most lines that demonstrated resistance in 2016 and 2018. There were no markers in lines VIR 768 and VIR 800, whereas in ТА 716-18 the markers of Plarg and Pl8 were present.Conclusion. As a result of the long-term studies, a trait-specific genetic collection was established for sunflower. It comprises genotyped lines with various effective DM resistance genes. Lines ТА 716-18, VIR 768 and VIR 800 appeared highly resistant to the pathogen and probably possess new resistance genes/alleles introgressed from wild species

Selective Constraints on Amino Acids Estimated by a Mechanistic Codon Substitution Model with Multiple Nucleotide Changes

Empirical substitution matrices represent the average tendencies of substitutions over various protein families by sacrificing gene-level resolution. We develop a codon-based model, in which mutational tendencies of codon, a genetic code, and the strength of selective constraints against amino acid replacements can be tailored to a given gene. First, selective constraints averaged over proteins are estimated by maximizing the likelihood of each 1-PAM matrix of empirical amino acid (JTT, WAG, and LG) and codon (KHG) substitution matrices. Then, selective constraints specific to given proteins are approximated as a linear function of those estimated from the empirical substitution matrices. Akaike information criterion (AIC) values indicate that a model allowing multiple nucleotide changes fits the empirical substitution matrices significantly better. Also, the ML estimates of transition-transversion bias obtained from these empirical matrices are not so large as previously estimated. The selective constraints are characteristic of proteins rather than species. However, their relative strengths among amino acid pairs can be approximated not to depend very much on protein families but amino acid pairs, because the present model, in which selective constraints are approximated to be a linear function of those estimated from the JTT/WAG/LG/KHG matrices, can provide a good fit to other empirical substitution matrices including cpREV for chloroplast proteins and mtREV for vertebrate mitochondrial proteins. The present codon-based model with the ML estimates of selective constraints and with adjustable mutation rates of nucleotide would be useful as a simple substitution model in ML and Bayesian inferences of molecular phylogenetic trees, and enables us to obtain biologically meaningful information at both nucleotide and amino acid levels from codon and protein sequences.Comment: Table 9 in this article includes corrections for errata in the Table 9 published in 10.1371/journal.pone.0017244. Supporting information is attached at the end of the article, and a computer-readable dataset of the ML estimates of selective constraints is available from 10.1371/journal.pone.001724

Exploratory Study of the Long-Term Persistence of <i>Yersinia pestis</i> in the Cells of Soil-Inhabiting Ameba - <i>Acanthamoeba Sp.</i>

Objective of the study is to explore the feasibility of the long-term persistence of Yersinia pestis strains in association with ameba - Acanthamoeba sp. Materials and methods. Investigated has been interaction of ameba - Acanthamoeba sp., isolated from rodent burrows in the Pre-Caspian sandy, Volga-Ural steppe, and Pre-Caspian North-Western steppe natural foci, with 4 strains of Y. pestis of the main subspecies, 1 strain of caucasica and 1 strain of altai subspecies. Results and discussion. It is established that the strains of the main subspecies survive in the cells of ameba at 26 °C and 20 % humidity (modeling of the drought conditions in the natural plague foci) within 2-4 months of experiment, and 10-20 times longer that in pure culture. Two strains of the non-main ssp. have not demonstrated an increase in persistency in association with Acanthamoeba sp., which may occur due to degraded resistance to phagocytosis in the ameba of this specie. Using fluorescent and transmission electronic microscopy, it is determined that the cells of plague agent persist in ameba cells in individual vacuoles, enclosed in endoplasmic reticulum. The data obtained may testify to the possible involvement of ameba Acanthamoeba sp. . into sustainment of Y. pestis in soil biocoenoses of natural plague foci