Pyrenophora teres: Population structure, virulence and aggressiveness in Southern Russia.

The barley net blotch agent Pyrenophora teres (Died) Drechs. is one of the dominant fungal pathogens in agricultural crops worldwide. Here we aim to study the aggressiveness and virulence of P. teres populations collected at different ontogenesis stages (BBCH 30 and BBCH 47) from winter barley cultivars of various resistance types: moderately resistant, moderately susceptible and highly susceptible. We observed a direct proportional relationship between cultivar resistance and the aggressiveness of P. teres populations collected in both growth phases of the host plant. The isolates collected at an early stage of host plant development have a large difference in aggressiveness criteria: colony growth rate, sporulation intensity, latency period, plant damage degree, and the number of identified races. At the BBCH 30 growth stage, the growth rate of fungus colonies selected from a resistant cultivar is 1.2 times higher than that of a susceptible cultivar. The growth rate of colonies selected from resistant and susceptible cultivars in the earlier BBCH 30 stage is 1.04 times higher than the growth rate of colonies selected from the later phase. The sporulation intensity of fungal populations selected from a resistant cultivar is higher than that of populations selected from a susceptible cultivar (for BBCH 30-5.4 times, for BBCH 47-4.0 times); and it is 1.3 times higher in an earlier phase of plant development. Correlation between colony growth rate and spore formation rate in the BBCH 30 is r = 0.4. A high correlation level (r = 0.9) and notable difference between the variants were revealed when studying the duration of the latent period. The average value of plant damage by the P. teres from resistant cultivar is 4 times higher than from the susceptible cultivar in the BBCH 30 stage; and 12 times - in the BBCH 47 stage. There is a moderate negative correlation between the plant damage degree and the number of races identified from the fungal population, r = -0.59 for the BBCH 30, r = -0.8 for the BBCH 47. The number of races identified from P. teres populations collected in the late phase of plant growth was one third less. Our study helped to acquire new knowledge about intrapopulation processes under the influence of various factors - plant growth stage and cultivar genotype. The results obtained are the basis for the development of adaptive-integrated techniques for managing populations of the hemibiotrophic pathogen, barley net blotch.

Effectiveness of Leaf Rust Resistance Genes in the Adult and Juvenile Stages in Southern Russia in 2011-2020.

Puccinia triticina Erikss. is a causative agent of wheat leaf rust spread worldwide. Wheat rust is a major disease on wheat in southern regions of Russia, which are leaders in grain production and have favorable conditions for pathogen development. In this paper we studied the effectiveness of 52 NILs of cv. Thatcher with Lr genes in field trials and 41 NILs-in the juvenile phase in a greenhouse during 2011-2020. We conclude that the lines with Lr9, Lr42 and Lr43+24 genes remained immune in the adult phase during ten years of research. Lines with Lr genes: 19, 24, 29, 36, 37, 38, 43, 45, 47, 50 showed efficiency in field tests (1-5 R on the CIMMYT scale). No immune lines to Puccinia triticina were registered in the juvenile phase during 2011-2020. The line with the Lr9 gene remained immune up to 2020; Lr19 and Lr41-up to 2015; Lr42-up to 2018, and Lr50-up to 2019. In 2020, there was an increase of P. triticina isolates with virulence to Thatcher lines with Lr: 9, 14a, 16, 19, 21, 28, 30, 33, 40, 45, W, 50. Additionally, we registered a change in infection types towards more susceptible in isogenic Lr gene lines: 1, 2a, 12, 14b, 15, 18, 20, 23, 25, 28, 29, 32, 35, 36, 37, 38, 40, 44, 45 in the field. A sharp increase in the frequencies of virulent isolates was recorded in 2018-2020 due to unfavorable weather in the growing seasons. This indicates the ability of a dangerous pathogen to rapidly evolve in response to biotic and abiotic stresses. Therefore, annual monitoring of the reaction of isogenic lines, selected released varieties and the study of the virulence of the phytopathogen are important measures necessary to prevent and control leaf rust in grain-producing regions of the world.

Resistance of winter wheat varieties to tan spot in the North Caucasus region of Russia.

Tan spot caused by Pyrenophora tritici-repentis (Died.) Drechsler, in recent years, occupies an increasingly large area on the territory of Russia. Due to the wide distribution and economic significance of this disease, the search for resistant plants to the pathogen is relevant. This paper presents the results of a field assessment for 2017-2019 of 34 regionally distributed winter wheat varieties of Russian selection for resistance to P. tritici-repentis in the North Caucasus region of Russia. Field resistance - the development of the disease up to 30% against the background of artificial infection for three years was shown by 20.5% of the studied varieties. Wheat varieties were assessed for resistance to isolates of tan spot identified as races 1, 3, and 4 in the greenhouse at the seedling stage. The number of resistant accessions for each race was different and ranged from 12 to 20. The 12 varieties showed resistance to race 1, 14 varieties to race 3, 20 varieties to race 4. This research showed that the resistance to tan spot of studied varieties was race-specific. A functional allele of the susceptibility gene Tsn1 to P. tritici-repentis isolates, producing the toxin Ptr ToxA, was diagnosed by PCR method. Of the analyzed 34 varieties, 13 had a dominant allele of the Tsn1 (Tsn1+), and 21 had a recessive allele in the tsn1tsn1 homozygous state. All Tsn1+ varieties, and most varieties with recessive alleles tsn1tsn1, were susceptible to tan spot in the field. Varieties Dolya, Gurt, Lebed and Sila, which showed field resistance, had the tsn1tsn1 genotype. The expected reaction of varieties with different allelic composition of the Tsn1 gene to inoculation with the isolate of race 1, according to the generally accepted model of "gene-to-gene" interaction, did not coincide with that observed in reality, which confirms the results obtained by other authors. Research results demonstrate the effect of weather conditions on the susceptibility of wheat varieties to tan spot. In years with higher humidity and higher average air temperatures, the susceptibility response to the disease was observed in more varieties than in drier years. The studies show that the main part (79.5%) of winter wheat varieties of Russian selection widely zoned in the North Caucasus region of Russia are susceptible to P. tritici-repentis. Varieties that have been resistant to the pathogen in the adult phase in the field for three years and to the pathogen races in which the recessive allele of the tsn1 gene has been identified may be of interest as sources of resistance for developing new disease-resistant varieties.

Annotated catalogue of type specimens of flatfishes (Osteichthyes: Pleuronectiformes) in the Zoological Institute, St. Petersburg, Russia.

A complete catalogue is provided for the type specimens of flatfishes curated in the ichthyological collection of the Zoological Institute, St. Petersburg. The collection contains a total of 138 type specimens, representing 25 species and one subspecies of eight different flatfish families. The catalogue includes: photographs of type specimens, radiographs of holotypes or largest syntypes, number of specimens, original sampling data (locality, coordinates, depth, collection date and collector), and select morphometric characters for each specimen.

Comparative analyses of the IV group oxides additives influence on the sintering kinetics of zirconia nanopowders.

Ceramics materials based on yttria stabilised tetragonal zirconia nanopowders (3Y-TZP) are widely used in the production fuel cells, oxygen sensors, refractories, etc. and intensively studied due to their outstanding mechanical and electrical properties. To obtain ceramics with specific properties different additives can be used. This allow for control over the features of a nanopowder' structure and its consolidation during the sintering process. It is important examine in detail the initial sintering stage of tetragonal zirconia based nanopowders modified by third element additives. The present paper shows the impact of SiO2 and SnO2 additives and the influence of different methods of dopant addition (co-precipitation and mechanical mixing) on the kinetics of the initial sintering stage of tetragonal zirconia nanopowders. It demonstrates that sintering mechanism is changed by the addition of a small amount SiO2 and SnO2 by volume to the grain boundary diffusion in 3Y-TZP nanopowders obtained by the co-precipitation method. This change led to increased activation energy. This paper explores the reasons for the acceleration in the sintering process of nanopowders 3Y-TZP with SiO2 and SnO2 additives obtained by the mixing method. It shows that the sintering mechanism is the same as that of the initial 3Y-TZP powder obtained by the co-precipitation technique. The volume diffusion mechanism was the predominant mechanism at the initial sintering stage and was accompanied by a decrease in the activation energy of the sintering process.

The Effect of a Small Amount SiO2 on Sintering Kinetics of Tetragonal Zirconia Nanopowders.

In the present paper the sintering behavior of 3 mol% yttria-stabilized zirconia (3Y-TZP) with and without small amount (0.2 wt %) of SiO2 additive was investigated. It has been studied the silica impact which was added in two ways (co-precipitation and mechanical mixing) on sintering kinetics of 3Y-TZP nanopowders at the initial sintering stage. It was found the silica additive leads to the changing in the predominant sintering mechanism at the initial sintering stage from volume (VD) to the grain boundary diffusion (GBD) in nanopowders obtained by co-precipitation. It was shown that the way of silica addition also significantly influence the sintering kinetics of 3Y-TZP. In case of nanopowders with silica additive obtained by mixing method, sintering process occurred due to the predominance of VD mechanism. It was found that the silica additive and the mechanical activation leads to the acceleration of the sintering process.

Influence of Obtaining Conditions on Kinetics of the Initial Sintering Stage of Zirconia Nanopowders.

The present paper is devoted to the problem of sintering ceramics based on yttria-stabilized zirconia (Y-TZP). In this paper, we studied the effect of two obtaining methods (co-precipitation and technical hydrolysis) on sintering kinetics of Y-TZP nanopowders. We used the constant rate of heating (CRH) method at different heating rates for determining the sintering mechanisms. The basic mechanism and activation energy (Q) of diffusion at the initial sintering stage were estimated using the sintering rate equations that are applicable to the CRH data. We found that nanopowder 3Y-TZP produced by the co-precipitation method (DIPE) was sintered according to the volume diffusion mechanism (n = 1/2) and nanopowder TZ-3Y (TOSOH) produced by the technical hydrolysis was sintered according to the grain boundary diffusion mechanism (n = 1/3).

Five-year trends in epidemiology and prevention of mother-to-child HIV transmission, St. Petersburg, Russia: results from perinatal HIV surveillance.

BACKGROUND: The HIV epidemic in Russia has increasingly involved reproductive-aged women, which may increase perinatal HIV transmission. METHODS: Standard HIV case-reporting and enhanced perinatal HIV surveillance systems were used for prospective assessment of HIV-infected women giving birth in St. Petersburg, Russia, during 2004-2008. Trends in social, perinatal, and clinical factors influencing mother-to-child HIV transmission stratified by history of injection drug use, and rates of perinatal HIV transmission were assessed using two-sided χ2 or Cochran-Armitage tests. RESULTS: Among HIV-infected women who gave birth, the proportion of women who self-reported ever using injection drugs (IDUs) decreased from 62% in 2004 to 41% in 2008 (P<0.0001). Programmatic improvements led to increased uptake of the following clinical services from 2004 to 2008 (all P<0.01): initiation of antiretroviral prophylaxis at ≤28 weeks gestation (IDUs 44%-54%, non-IDUs 45%-72%), monitoring of immunologic (IDUs 48%-64%, non-IDUs 58%-80%) and virologic status (IDUs 8%-58%, non-IDUs 10%-75%), dual/triple antiretroviral prophylaxis (IDUs 9%-44%, non-IDUs 14%-59%). After initial increase from 5.3% (95% confidence interval [CI] 3.5%-7.8%) in 2004 to 8.5% (CI 6.1%-11.7%) in 2005 (P<0.05), perinatal HIV transmission decreased to 5.3% (CI 3.4%-8.3%) in 2006, and 3.2% (CI 1.7%-5.8%) in 2007 (P for trend<0.05). However, the proportion of women without prenatal care and without HIV testing before labor and delivery remained unchanged. CONCLUSIONS: Reduced proportion of IDUs and improved clinical services among HIV-infected women giving birth were accompanied by decreased perinatal HIV transmission, which can be further reduced by increasing outreach and HIV testing of women before and during pregnancy.

Potential bridges of heterosexual HIV transmission from drug users to the general population in St. Petersburg, Russia: is it easy to be a young female?

The epidemic of HIV in St. Petersburg, which is currently concentrated among injection drug users (IDUs), may be penetrating into the general population. Non-IDUs who have IDU sex partners (SP) could be potential bridges in an expanding epidemic. To investigate potential bridges, we accrued a convenience sample of 288 non-IDUs whose HIV diagnosis was attributed to sexual transmission and we determined the proportion that had IDUs among their SP. Having IDU SP ever (lifetime) and IDU SP in the last year were the key variables for the analysis of potential bridges in this study. The interaction of gender and age was found to be a significant predictor of having lifetime IDU SP (p = 0.006, chi (2) test) and IDU SP in the last year (p = 0.05, chi (2) test): females aged 26 and younger were more likely to have both lifetime IDU SP and IDU SP in the last year. Among the group of young females, 46% reported ever having an IDU SP. Out of young women reporting ever having an IDU SP, 85% also reported at least one lifetime non-IDU SP. Among the females aged 26 or younger, a lower level of education (odds ratio [OR] = 2.7, confidence interval [CI] = 1.1-6.7), being born in St. Petersburg (OR = 2.9, CI = 1.2-7.2), and alcohol use in the last 30 days (OR = 3.5, CI = 1.3-9.6) were significant correlates for ever having had an IDU SP. Urgent efforts are necessary to expand HIV prevention to target the potential bridging population to prevent further transmission.

HIV seroprevalence in street youth, St. Petersburg, Russia.

BACKGROUND: Reliable data on HIV infection among Russian street youth are unavailable. The purpose of this study was to assess HIV seroprevalence among street youth in St Petersburg and to describe social, sexual, and behavioral characteristics associated with HIV infection. METHODS: A cross-sectional assessment conducted during January-May 2006 included city-wide mapping of 41 street youth locations, random selection of 22 sites, rapid HIV testing for all consenting 15-19-year-old male and female street youth at these sites, and an interviewer-administered survey. Adjusted odds ratios (AOR) were calculated using logistic regression, accounting for intracluster homogeneity. RESULTS: Of 313 participants, 117 (37.4%, 95% confidence interval 26.1-50.2%) were HIV infected. Subgroups with the highest seroprevalences included double orphans (64.3%), those with no place to live (68.1%), those previously diagnosed with a sexually transmitted infection (STI; 70.5%), those currently sharing needles (86.4%), and those currently using inhalants (60.5%) or injection drugs (78.6%), including Stadol (82.3%) or heroin (78.1%). Characteristics independently associated with HIV infection included injecting drugs (AOR 23.0), sharing needles (AOR 13.3), being a double or single orphan (AOR 3.3 and 1.8), having no place to live (AOR 2.4), and being diagnosed with a STI (AOR 2.1). Most HIV-infected street youth were sexually active (96.6%), had multiple partners (65.0%), and used condoms inconsistently (80.3%). DISCUSSION: Street youth aged 15-19 years in St Petersburg, Russia, have an extraordinarily high HIV seroprevalence. In street youth who are injection drug users, HIV seroprevalence is the highest ever reported for eastern Europe and is among the highest in the world.

Rapid HIV testing, pregnancy, antiretroviral prophylaxis and infant abandonment in St Petersburg.

In St Petersburg, Russia, a rapid HIV-testing programme was implemented in April 2004 for high-risk women giving birth. Among 670 women without prenatal care who received rapid HIV testing, 6.4% (43) had positive results. Among HIV-positive mothers, receipt of intrapartum antiretroviral prophylaxis increased significantly compared to pre-programme levels (76 versus 41%). Additionally, infant abandonment increased significantly (50% versus 26%), and was 10 times greater in women with unintended versus intended pregnancies (73% versus 7%).