ВЛИЯНИЕ ЭТРЕЛА В УСЛОВИЯХ КРАСНОДАРСКОГО КРАЯ НА ЦВЕТЕНИЕ МУЖСКИХ ЦВЕТКОВ РАСТЕНИЙ КАБАЧКА С РАЗЛИЧНОЙ ГЕНЕТИЧЕСКОЙ ВЫРАЖЕННОСТЬЮ ПОЛА

Depending on the genotype of monoecious plants Cucurbitaceae family may have different gender expressions: predominantly female, mixed and predominantlymale type of flowering. However, the degree of sexual differentiation can be changedunder the influence of abiotic and endogenous factors. Among the chemicals that affect the level of female flowering in pumpkin crops, preparations based on 2-chloroethylphosphonic acid (Ethephon or Etrelle) are the most promising for hybrid seed production. Study of plant response of squash Cucurbita pepo var. giromontina with varying sex expressions on the treatments with Etrelle revealed common conformities and specificities of preparation action in the condition of Krasnodar region. It is shown the use of treatment once is not effective even if the high concentration range, 500-1100 mg/L, was taken. On gender switch was effectively influenced successive plant treatments with Etrelle at stages of 3-5 true leaves in a wide concentration range from 250 to 700 mg /L., where the restraining was that the start of male flower blossoming was 14-25 days after female flower blossoming. K69 line with predominantly female flowering was more responsive to the variation of concentration and frequency of treatments whereas the line K49 with male flowering was less responsive to the frequency of treatments. It is shown that in the range of effective concentrations, Etrelle may have phytotoxic effects on the growth and development of squash plants at the time of restraining flowering of male flowers. It is important to  ake that into account when choosing a regime of preparation treatments for chemical castration of maternal forms in hybrid seed production of this crop.В зависимости от генотипа однодомные растения семейства тыквенных могут иметь различную выраженность пола: преимущественно женский, смешанный и  преимущественно мужской тип цветения. Однако степень половой дифференциации изменяется под действием абиотических и эндогенных факторов. Среди химических веществ, влияющих на уровень женского цветения растений тыквенных культур, наибольший интерес с точки зрения гибридного семеноводства представляют препараты на основе 2-хлорэтилфосфоновой кислоты (Этрел или Этефон). Изучение реакции растений кабачка Cucurbita pepo var. giromontina с различной выраженностью пола на обработку Этрелом позволило выявить общие закономерности и специфику действия препарата в условиях Краснодарского края. Установлено, что использование однократной обработки на всех изучаемых генотипах является малоэффективным, даже в диапазоне высоких концентраций 500-1100 мг/л д.в. На смещение сексуализации эффективно влияют последовательные обработки растений кабачка Этрелом на стадиях развития 3-5 настоящих листа в диапазоне концентраций от 250 до 700 мг/л д.в., где сдерживание начала цветения мужских цветков после распускания женских составляло 14-25 суток. На изменение концентрации и кратности обработок более отзывчивы растения линии К69 с преимущественно женским типом. В меньшей степени на кратность обработок реагируют растения линии К49, с преимущественно мужским типом цветения. Показано, что в диапазоне эффективных концентраций, сдерживая цветение мужских цветков, Этрел может оказывать фитотоксическое действие нарост и развитие растений кабачка, что важно учитывать при выборе регламента применения препарата для химической кастрации материнских форм при гибридном семеноводстве этой культуры. Для практического применения препарата Этрел в условиях Краснодарского края оптимальным следует считать трехкратную обработку (фазы 3+4+5 н.л.) в диапазоне концентраций 250-350 мг/л д.в. в зависимости от генотипа материнской формы

Artificial Neural Networks as Non-Linear Extensions of Statistical Methods in Astronomy

We attempt to de-mistify Artificial Neural Networks (ANNs) by considering special cases which are related to other statistical methods common in Astronomy and other fields. In particular we show how ANNs generalise Bayesian methods, multi-parameter fitting, Principal Component Analysis (PCA), Wiener filtering and regularisation methods. Examples of morphological classification of galaxies illustrate how non-linear ANNs improve on linear techniques.Comment: 9 pages, uu-encoded compressed postscript file. Also available by anonymous ftp to cast0.ast.cam.ac.uk (131.111.68.35) at ftp://cast0.ast.cam.ac.uk/pub/lahav/vistas/vistas4.ps.Z with figure at ftp://cast0.ast.cam.ac.uk/pub/lahav/vistas/fig1.ps.Z To appear in Vistas in Astronomy, special issue on Artificial Neural Networks in Astronom

The Effector Domain of MARCKS Is a Nuclear Localization Signal that Regulates Cellular PIP2 Levels and Nuclear PIP2 Localization

Translocation to the nucleus of diacylglycerol kinase (DGK)– ζ is dependent on a sequence homologous to the effector domain of Myristoylated Alanine Rich C-Kinase Substrate (MARCKS). These data would suggest that MARCKS could also localize to the nucleus. A single report demonstrated immunofluorescence staining of MARCKS in the nucleus; however, further experimental evidence confirming the specific domain responsible for this localization has not been reported. Here, we report that MARCKS is present in the nucleus in GBM cell lines. We then over-expressed wild-type MARCKS (WT) and MARCKS with the effector domain deleted (ΔED), both tagged with V5-epitope in a GBM cell line with low endogenous MARCKS expression (U87). We found that MARCKS-WT localized to the nucleus, while the MARCKS construct without the effector domain remained in the cytoplasm. We also found that over-expression of MARCKS-WT resulted in a significant increase in total cellular phosphatidyl-inositol (4,5) bisphosphate (PIP2) levels, consistent with prior evidence that MARCKS can regulate PIP2 levels. We also found increased staining for PIP2 in the nucleus with MARCKS-WT over-expression compared to MARCKS ΔED by immunofluorescence. Interestingly, we observed MARCKS and PIP2 co-localization in the nucleus. Lastly, we found changes in gene expression when MARCKS was not present in the nucleus (MARCKS ΔED). These data indicate that the MARCKS effector domain can function as a nuclear localization signal and that this sequence is critical for the ability of MARCKS to regulate PIP2 levels, nuclear localization, and gene expression. These data suggests a novel role for MARCKS in regulating nuclear functions such as gene expression

Impact of viral replication inhibition by entecavir on peripheral T lymphocyte subpopulations in chronic hepatitis B patients

<p>Abstract</p> <p>Background</p> <p>To investigate dynamic fluctuations of serum viral load and peripheral T-lymphocyte subpopulations of chronic hepatitis B patients and their correlation during entecavir therapy.</p> <p>Methods</p> <p>Fifty-five patients received entecavir 0.5 mg/d therapy. Serum HBV DNA load was measured by Real-Time-PCR, and the levels of peripheral T-lymphocyte subpopulations by flow cytometry biweekly, every four weeks and every eight weeks during weeks 1–12, 13–24 and 24–48, respectively. Multilevel modelling was used to analyse the relationship between these variables.</p> <p>Results</p> <p>Of the 55 patients, all HBeAg positive and with detectable HBV DNA, the majority (81.8%) had serum levels of HBV DNA over 10⁷copies per milliliter. HBV viral load dropped sharply during the first two weeks. In 28 and 43 patients, the level became undetectable from week 24 and 48, respectively. Using pre-therapy level as the reference, a significant decrease in CD8⁺T cells and increase in CD4⁺T cells were found from week 12. Both parameters and CD4⁺/CD8⁺ratio steadily improved throughout the 48 weeks. Multilevel analyses showed that the level of decrement of HBV DNA was associated with the increment of T-lymphocyte activities only in the later period (4–48 week). After 4 weeks of therapy, for each log₁₀scale decrement of HBV DNA, the percentage of CD4⁺lymphocyte was increased by 0.49 and that of CD8⁺decreased by 0.51.</p> <p>Conclusion</p> <p>T-lymphocyte subpopulations could be restored partially by entecavir treatment in patients with chronic hepatitis B concurrently with reduction of viremia.</p

The migration of physicians from sub-Saharan Africa to the United States of America: measures of the African brain drain

BACKGROUND: The objective of this paper is to describe the numbers, characteristics, and trends in the migration to the United States of physicians trained in sub-Saharan Africa. METHODS: We used the American Medical Association 2002 Masterfile to identify and describe physicians who received their medical training in sub-Saharan Africa and are currently practicing in the USA. RESULTS: More than 23% of America's 771 491 physicians received their medical training outside the USA, the majority (64%) in low-income or lower middle-income countries. A total of 5334 physicians from sub-Saharan Africa are in that group, a number that represents more than 6% of the physicians practicing in sub-Saharan Africa now. Nearly 86% of these Africans practicing in the USA originate from only three countries: Nigeria, South Africa and Ghana. Furthermore, 79% were trained at only 10 medical schools. CONCLUSIONS: Physician migration from poor countries to rich ones contributes to worldwide health workforce imbalances that may be detrimental to the health systems of source countries. The migration of over 5000 doctors from sub-Saharan Africa to the USA has had a significantly negative effect on the doctor-to-population ratio of Africa. The finding that the bulk of migration occurs from only a few countries and medical schools suggests policy interventions in only a few locations could be effective in stemming the brain drain

Molecular Modeling of Mechanosensory Ion Channel Structural and Functional Features

The DEG/ENaC (Degenerin/Epithelial Sodium Channel) protein family comprises related ion channel subunits from all metazoans, including humans. Members of this protein family play roles in several important biological processes such as transduction of mechanical stimuli, sodium re-absorption and blood pressure regulation. Several blocks of amino acid sequence are conserved in DEG/ENaC proteins, but structure/function relations in this channel class are poorly understood. Given the considerable experimental limitations associated with the crystallization of integral membrane proteins, knowledge-based modeling is often the only route towards obtaining reliable structural information. To gain insight into the structural characteristics of DEG/ENaC ion channels, we derived three-dimensional models of MEC-4 and UNC-8, based on the available crystal structures of ASIC1 (Acid Sensing Ion Channel 1). MEC-4 and UNC-8 are two DEG/ENaC family members involved in mechanosensation and proprioception respectively, in the nematode Caenorhabditis elegans. We used these models to examine the structural effects of specific mutations that alter channel function in vivo. The trimeric MEC-4 model provides insight into the mechanism by which gain-of-function mutations cause structural alterations that result in increased channel permeability, which trigger cell degeneration. Our analysis provides an introductory framework to further investigate the multimeric organization of the DEG/ENaC ion channel complex

Unsuccessful therapy with adefovir and entecavir-tenofovir in a patient with chronic hepatitis B infection with previous resistance to lamivudine: a fourteen-year evolution of hepatitis B virus mutations

<p>Abstract</p> <p>Background</p> <p>Complex mutants can be selected under sequential selective pressure by HBV therapy. To determine hepatitis B virus genomic evolution during antiviral therapy we characterized the HBV quasi-species in a patient who did no respond to therapy following lamivudine breakthrough for a period of 14 years.</p> <p>Case Presentation</p> <p>The polymerase and precore/core genes were amplified and sequenced at determined intervals in a period of 14 years. HBV viral load and HBeAg/Anti-HBe serological profiles as well as amino transferase levels were also measured. A mixture of lamivudine-resistant genotype A2 HBV strains harboring the rtM204V mutation coexisted in the patient following viral breakthrough to lamivudine. The L180M+M204V dominant mutant displayed strong lamivudine-resistance. As therapy was changed to adefovir, then to entecavir, and finally to entecavir-tenofovir the viral load showed fluctuations but lamivudine-resistant strains continued to be selected, with minor contributions to the HBV quasi-species composition of additional resistance-associated mutations. At the end of the 14-year follow up period, high viral loads were predominant, with viral strains harboring the lamivudine-resistance signature rtL180M+M204V. The precore/core frame A1762T and G1764A double mutation was detected before treatment and remaining in this condition during the entire follow-up. Specific entecavir and tenofovir primary resistance-associated mutations were not detected at any time. Plasma concentrations of tenofovir indicated adequate metabolism of the drug.</p> <p>Conclusions</p> <p>We report the selection of HBV mutants carrying well-defined primary resistance mutations that escaped lamivudine in a fourteen-year follow-up period. With the exception of tenofovir resistance mutations, subsequent unselected primary resistance mutations were detected as minor populations into the HBV quasispecies composition during adefovir or entecavir monotherapies. Although tenofovir is considered an appropriate therapeutic alternative for the treatment of entecavir-unresponsive patients, its use was not effective in the case reported here.</p

Comparative analysis of somitogenesis related genes of the hairy/Enhancer of split class in Fugu and zebrafish

BACKGROUND: Members of a class of bHLH transcription factors, namely the hairy (h), Enhancer of split (E(spl)) and hairy-related with YRPW motif (hey) (h/E(spl)/hey) genes are involved in vertebrate somitogenesis and some of them show cycling expression. By sequence comparison, identified orthologues of cycling somitogenesis genes from higher vertebrates do not show an appropriate expression pattern in zebrafish. The zebrafish genomic sequence is not available yet but the genome of Fugu rubripes was recently published. To allow comparative analysis, the currently known Her proteins from zebrafish were used to screen the genomic sequence database of Fugu rubripes. RESULTS: 20 h/E(spl)/hey-related genes were identified in Fugu, which is twice the number of corresponding zebrafish genes known so far. A novel class of c-Hairy proteins was identified in the genomes of Fugu and Tetraodon. A screen of the human genome database with the Fugu proteins yielded 10 h/E(spl)/hey-related genes. By analysing the upstream sequences of the c-hairy class genes in zebrafish, Fugu and Tetraodon highly similar sequence stretches were identified that harbour Suppressor of hairless paired binding sites (SPS). This motif was also discovered in the upstream sequences of the her1 gene in the examined fish species. Here, the Su(h) sites are separated by longer intervening sequences. CONCLUSIONS: Our study indicates that not all her homologues in zebrafish have been isolated. Comparison to the human genome suggests a selective duplication of h/E(spl) genes in pufferfish or loss of members of these genes during evolution to the human lineage