Mechanisms of gap gene expression canalization in the Drosophila blastoderm

<p>Abstract</p> <p>Background</p> <p>Extensive variation in early gap gene expression in the <it>Drosophila </it>blastoderm is reduced over time because of gap gene cross regulation. This phenomenon is a manifestation of canalization, the ability of an organism to produce a consistent phenotype despite variations in genotype or environment. The canalization of gap gene expression can be understood as arising from the actions of attractors in the gap gene dynamical system.</p> <p>Results</p> <p>In order to better understand the processes of developmental robustness and canalization in the early <it>Drosophila </it>embryo, we investigated the dynamical effects of varying spatial profiles of Bicoid protein concentration on the formation of the expression border of the gap gene <it>hunchback</it>. At several positions on the anterior-posterior axis of the embryo, we analyzed attractors and their basins of attraction in a dynamical model describing expression of four gap genes with the Bicoid concentration profile accounted as a given input in the model equations. This model was tested against a family of Bicoid gradients obtained from individual embryos. These gradients were normalized by two independent methods, which are based on distinct biological hypotheses and provide different magnitudes for Bicoid spatial variability. We showed how the border formation is dictated by the biological initial conditions (the concentration gradient of maternal Hunchback protein) being attracted to specific attracting sets in a local vicinity of the border. Different types of these attracting sets (point attractors or one dimensional attracting manifolds) define several possible mechanisms of border formation. The <it>hunchback </it>border formation is associated with intersection of the spatial gradient of the maternal Hunchback protein and a boundary between the attraction basins of two different point attractors. We demonstrated how the positional variability for <it>hunchback </it>is related to the corresponding variability of the basin boundaries. The observed reduction in variability of the <it>hunchback </it>gene expression can be accounted for by specific geometrical properties of the basin boundaries.</p> <p>Conclusion</p> <p>We clarified the mechanisms of gap gene expression canalization in early <it>Drosophila </it>embryos. These mechanisms were specified in the case of <it>hunchback </it>in well defined terms of the dynamical system theory.</p

INNOVATIVE METHOD OF PERSONNEL MANAGEMENT: NON-STANDARD NON-MATERIAL MOTIVATION

The article studied the influence of non-material motivation to increase the innovativeness of personnel management. When writing the article, it was concluded that the basic principles of intangible motivation should be included in the company's innovative HR management strategy

Comprehensive Screening for COVID-19 at St. Petersburg Oncology Centre

Background. Clinical reports on the coronavirus disease 2019 (COVID-19) suggest its higher incidence and worse outcomes in cancer patients. Considering a rapid pace of the severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) pandemic, more data on the risk of contagion and syndrome course is required with this patient group.Aim. Estimation of the infection rate in cancer patients managed at the Oncology Centre.Materials and methods. This retrospective study included cancer patients managed at the Oncology Centre between 9 April 2020 and 27 May 2020 and routinely tested for SARS-CoV-2 in polymerase chain reaction (PCR) assays and/or COVID-19 in chest computed tomography (CT).Results and discussion. A total of 2,628 patients were included in the study, with 119 (4.5 %) confirmed to have COVID-19; 45/119 were PCR-positive, 95/119 had viral pneumonia in CT, 21/119 were positive for both tests. A total of 47.9 % cases were asymptomatic, 11.8 % revealed a mild single-symptom disease. COVID-19 ended in death in 2 (2.5 %) of 80 cases with a known outcome. In PCR results of both patient and staff screening, the virus detection rate was 3.0 % and 2.4 %, respectively (p = 0.33).Conclusion. A COVID-19 screening revealed no significant difference in the risk of contagion between cancer patients and staff of the Oncology Centre. PCR tests may perform false negative for COVID-19 in cancer patients and should be coupled with CT scanning. The infection is asymptomatic or clinically mild in most other cases

Features of fractal conformity and bioconsolidation in the early myogenesis gene expression and their relationship to the genetic diversity of chicken breeds

Simple Summary In the bodies of animals, including birds, gene expression leads to the synthesis of many proteins. To provide optimal cellular and organismal properties and functions, many genes should work in concert, reaching certain balanced relationships (or networks) between them and the intensities of their expression. Here, we studied the expression of several genes responsible for muscle formation and growth in chick embryos of diverse breeds belonging to various utility types. Using two mathematical (fractal) models and the respective indices, we showed that there are specific coordinated patterns of gene expression in the embryonic breast and thigh muscles. These patterns correlated with growth rate of chicks after hatching and depended on a utility type of the breeds studied. Overall, the proposed models contributed to an expanded understanding of the coordinated gene expression in early development and growth, providing additional characteristics of genetic diversity in chickens. Abstract Elements of fractal analysis are widely used in scientific research, including several biological disciplines. In this study, we hypothesized that chicken breed biodiversity manifests not only at the phenotypic level, but also at the genetic-system level in terms of different profiles of fractal conformity and bioconsolidation in the early myogenesis gene expression. To demonstrate this effect, we developed two mathematical models that describe the fractal nature of the expression of seven key genes in the embryonic breast and thigh muscles in eight breeds of meat, dual purpose, egg and game types. In the first model, we produced breed-specific coefficients of gene expression conformity in each muscle type using the slopes of regression dependencies, as well as an integral myogenesis gene expression index (MGEI). Additionally, breed fractal dimensions and integral myogenesis gene expression fractal dimension index (MGEFDI) were determined. The second gene expression model was based on plotting fractal portraits and calculating indices of fractal bioconsolidation. The bioconsolidation index of myogenesis gene expression correlated with the chick growth rate and nitric oxide (NO) oxidation rate. The proposed fractal models were instrumental in interpreting the genetic diversity of chickens at the level of gene expression for early myogenesis, NO metabolism and the postnatal growth of chicks

Unraveling signatures of chicken genetic diversity and divergent selection in breed-specific patterns of early myogenesis, nitric oxide metabolism and post-hatch growth

Due to long-term domestication, breeding and divergent selection, a vast genetic diversity in poultry currently exists, with various breeds being characterized by unique phenotypic and genetic features. Assuming that differences between chicken breeds divergently selected for economically and culturally important traits manifest as early as possible in development and growth stages, we aimed to explore breed-specific patterns and interrelations of embryo myogenesis, nitric oxide (NO) metabolism and post-hatch growth rate (GR). These characteristics were explored in eight breeds of different utility types (meat-type, dual purpose, egg-type, game, and fancy) by incubating 70 fertile eggs per breed. To screen the differential expression of seven key myogenesis associated genes (MSTN, GHR, MEF2C, MYOD1, MYOG, MYH1, and MYF5), quantitative real-time PCR was used. We found that myogenesis associated genes expressed in the breast and thigh muscles in a coordinated manner showing breed specificity as a genetic diversity signature among the breeds studied. Notably, coordinated (“accord”) expression patterns of MSTN, GHR, and MEFC2 were observed both in the breast and thigh muscles. Also, associated expression vectors were identified for MYOG and MYOD1 in the breast muscles and for MYOG and MYF5 genes in the thigh muscles. Indices of NO oxidation and post-hatch growth were generally concordant with utility types of breeds, with meat-types breeds demonstrating higher NO oxidation levels and greater GR values as compared to egg-type, dual purpose, game and fancy breeds. The results of this study suggest that differences in early myogenesis, NO metabolism and post-hatch growth are breed-specific; they appropriately reflect genetic diversity and accurately capture the evolutionary history of divergently selected chicken breeds

Electron transport in TiO2 probed by THz time-domain spectroscopy

Euan Hendry, F. Wang, J. Shan, T. F. Heinz, and Mischa Bonn, Physical Review B, Vol. 69, article 081101 (2004). "Copyright © 2004 by the American Physical Society."Electron transport in crystalline TiO2 (rutile phase) is investigated by frequency-dependent conductivity measurements using THz time-domain spectroscopy. Transport is limited by electron-phonon coupling, resulting in a strongly temperature-dependent electron-optical phonon scattering rate, with significant anisotropy in the scattering process. The experimental findings can be described by Feynman polaron theory within the intermediate coupling regime and allow for a determination of electron mobility

Breed-specific patterns of early myogenesis, nitric oxide metabolism, and post-hatch growth in relation to genetic diversity and divergent selection in chickens [Породоспецифичные модели раннего миогенеза, метаболизма оксида азота и постнатального роста в связи с генетическим разнообразием и разнонаправленной селекцией у кур]

Aims: There is currently a significant genetic diversity across poultry breeds as a result of long-term domestication, breeding, and divergent selection, with each breed having its own distinctive phenotypic and genetic characteristics [1,2]. We presumed and set out to investigate whether differences between chicken breeds divergently selected for economically and culturally significant traits [3] manifest as early as possible in development and growth stages. Methods: Breed-specific patterns and relationships of embryo myogenesis, nitric oxide (NO) metabolism, and post-hatch growth rate were studied and analyzed [4]. Results: Our research revealed that myogenesis genes were coordinatedly expressed in the thigh and breast muscles, demonstrating breed uniqueness. Indicators of NO oxidation and post-hatch growth were largely consistent with utility breed types, with meat breeds showing higher NO oxidation levels and better growth rate values in comparison to egg, dual purpose, game, and fancy breeds. Conclusions: The findings of this study indicate that breed-specific variations in early myogenesis, NO metabolism, and post-hatch growth adequately represent genetic variety and reliably depict the evolutionary history of diversely chosen chicken breeds

Spatial Bistability Generates hunchback Expression Sharpness in the Drosophila Embryo

During embryonic development, the positional information provided by concentration gradients of maternal factors directs pattern formation by providing spatially dependent cues for gene expression. In the fruit fly, Drosophila melanogaster, a classic example of this is the sharp on–off activation of the hunchback (hb) gene at midembryo, in response to local concentrations of the smooth anterior–posterior Bicoid (Bcd) gradient. The regulatory region for hb contains multiple binding sites for the Bcd protein as well as multiple binding sites for the Hb protein. Some previous studies have suggested that Bcd is sufficient for properly sharpened Hb expression, yet other evidence suggests a need for additional regulation. We experimentally quantified the dynamics of hb gene expression in flies that were wild-type, were mutant for hb self-regulation or Bcd binding, or contained an artificial promoter construct consisting of six Bcd and two Hb sites. In addition to these experiments, we developed a reaction–diffusion model of hb transcription, with Bcd cooperative binding and hb self-regulation, and used Zero Eigenvalue Analysis to look for multiple stationary states in the reaction network. Our model reproduces the hb developmental dynamics and correctly predicts the mutant patterns. Analysis of our model indicates that the Hb sharpness can be produced by spatial bistability, in which hb self-regulation produces two stable levels of expression. In the absence of self-regulation, the bistable behavior vanishes and Hb sharpness is disrupted. Bcd cooperative binding affects the position where bistability occurs but is not itself sufficient for a sharp Hb pattern. Our results show that the control of Hb sharpness and positioning, by hb self-regulation and Bcd cooperativity, respectively, are separate processes that can be altered independently. Our model, which matches the changes in Hb position and sharpness observed in different experiments, provides a theoretical framework for understanding the data and in particular indicates that spatial bistability can play a central role in threshold-dependent reading mechanisms of positional information