A Phenotype at Last: Essential Role for the Yersinia enterocolitica Ysa Type III Secretion System in a Drosophila melanogaster S2 Cell Model

ABSTRACT The highly pathogenic Yersinia enterocolitica strains have a chromosomally encoded type III secretion system (T3SS) that is expressed and functional in vitro only when the bacteria are cultured at 26°C. Mutations that render this system nonfunctional are slightly attenuated in the mouse model of infection only following an oral inoculation and only at early time points postinfection. The discrepancy between the temperature required for the Ysa gene expression and the physiological temperature required for mammalian model systems has made defining the role of this T3SS challenging. Therefore, we explored the use of Drosophila S2 cells as a model system for studying Ysa function. We show here that Y. enterocolitica is capable of infecting S2 cells and replicating intracellularly to high levels, an unusual feature of this pathogen. Importantly, we show that the Ysa T3SS is required for robust intracellular replication. A secretion-deficient mutant lacking the secretin gene, ysaC , is defective in replication within S2 cells, marking the first demonstration of a pronounced Ysa-dependent virulence phenotype. Establishment of S2 cells as a model for Y. enterocolitica infection provides a versatile tool to elucidate the role of the Ysa T3SS in the life cycle of this gastrointestinal pathogen

I–II Loop Structural Determinants in the Gating and Surface Expression of Low Voltage-Activated Calcium Channels

The intracellular loops that interlink the four transmembrane domains of Ca2+- and Na+-channels (Cav, Nav) have critical roles in numerous forms of channel regulation. In particular, the intracellular loop that joins repeats I and II (I–II loop) in high voltage-activated (HVA) Ca2+ channels possesses the binding site for Cavβ subunits and plays significant roles in channel function, including trafficking the α1 subunits of HVA channels to the plasma membrane and channel gating. Although there is considerable divergence in the primary sequence of the I–II loop of Cav1/Cav2 HVA channels and Cav3 LVA/T-type channels, evidence for a regulatory role of the I–II loop in T-channel function has recently emerged for Cav3.2 channels. In order to provide a comprehensive view of the role this intracellular region may play in the gating and surface expression in Cav3 channels, we have performed a structure-function analysis of the I–II loop in Cav3.1 and Cav3.3 channels using selective deletion mutants. Here we show the first 60 amino acids of the loop (post IS6) are involved in Cav3.1 and Cav3.3 channel gating and kinetics, which establishes a conserved property of this locus for all Cav3 channels. In contrast to findings in Cav3.2, deletion of the central region of the I–II loop in Cav3.1 and Cav3.3 yielded a modest increase (+30%) and a reduction (−30%) in current density and surface expression, respectively. These experiments enrich our understanding of the structural determinants involved in Cav3 function by highlighting the unique role played by the intracellular I–II loop in Cav3.2 channel trafficking, and illustrating the prominent role of the gating brake in setting the slow and distinctive slow activation kinetics of Cav3.3

Morphological and immunohistochemical characteristics of human trigeminal ganglion neurons in the prenatal period of development

Introduction: Data related to the amount, size and morphological characteristics of cell elements of sensory ganglia at different stages of prenatal development has not been fully elucidated in recent scientific publications. At the same time publications considering the study of cell structure of trigeminal ganglion in the postnatal period confirm heterogeneity of its neurons. The aim of the research was to study morphological and immunohistochemical characteristics of human trigeminal ganglion neurons at 12-14 weeks of prenatal development. Material and Methods: The study was made on 24 trigeminal ganglions of 12 human fetuses at 12 to 14 weeks of prenatal development after abortion made on social and medical indications. Results: At the studied period of the intrauterine development nerve cells of the trigeminal ganglion significantly differed in size, tinctorial properties and degree of argentophility of the perikaryon. At the same time, the number of small nerve cells with an average diameter of less than 15 pm prevailed. Immunohistochemical study allowed detecting the apparent Bd-2 expression in the overwhelming number of small neurons; the expression of this marker has been observed in 50% of cells of the medium-sized neurons. No Bd-2 expression has been found in most of the large neurons. Almost all the neurons, regardless of the size, showed moderate Ki-67 expression, protein S-100. VEGF expression has also occurred in the vast majority of the nerve cells of all size groups. Conclusions: 1. Human trigeminal ganglion neurons both at 12-14 weeks of prenatal development and in postnatal period are represented by heterogeneous population. 2. Polymorphism of trigeminal ganglion neurons has been found by all applied techniques. 3. Detected polymorphism is the evidence of processes of maturation and differentiation of neurons in human trigeminal ganglion at 12-14 weeks of prenatal developmen

Исследование влияния проводимости металлических электродов на СВЧ-свойства магнонных кристаллов

Theoretical model for the ferrite spin-wave magnonic crystals has been developed. A considered magnonic crystal has a construction of periodically metallized thin ferrite film. An influence of various magnonic crystal parameters on its transmission-loss characteristic was analyzed. It is shown that a developed model described with high accuracy the microwave transmission-loss characteristics.Разработана теоретическая модель, описывающая распространение спиновых волн в магнонных кристаллах, представляющих периодически металлизированные ферритовые пленки. В разработанной модели учтена конечная проводимость металлизации. Проанализировано влияние различных параметров магнонного кристалла на его передаточные СВЧ-характеристики. Разработанная теория с высокой точностью описывает результаты эксперимента

Orientation of the Calcium Channel β Relative to the α12.2 Subunit Is Critical for Its Regulation of Channel Activity

BACKGROUND: The Ca(v)beta subunits of high voltage-activated Ca(2+) channels control the trafficking and biophysical properties of the alpha(1) subunit. The Ca(v)beta-alpha(1) interaction site has been mapped by crystallographic studies. Nevertheless, how this interaction leads to channel regulation has not been determined. One hypothesis is that betas regulate channel gating by modulating movements of IS6. A key requirement for this direct-coupling model is that the linker connecting IS6 to the alpha-interaction domain (AID) be a rigid structure. METHODOLOGY/PRINCIPAL FINDINGS: The present study tests this hypothesis by altering the flexibility and orientation of this region in alpha(1)2.2, then testing for Ca(v)beta regulation using whole cell patch clamp electrophysiology. Flexibility was induced by replacement of the middle six amino acids of the IS6-AID linker with glycine (PG6). This mutation abolished beta2a and beta3 subunits ability to shift the voltage dependence of activation and inactivation, and the ability of beta2a to produce non-inactivating currents. Orientation of Ca(v)beta with respect to alpha(1)2.2 was altered by deletion of 1, 2, or 3 amino acids from the IS6-AID linker (Bdel1, Bdel2, Bdel3, respectively). Again, the ability of Ca(v)beta subunits to regulate these biophysical properties were totally abolished in the Bdel1 and Bdel3 mutants. Functional regulation by Ca(v)beta subunits was rescued in the Bdel2 mutant, indicating that this part of the linker forms beta-sheet. The orientation of beta with respect to alpha was confirmed by the bimolecular fluorescence complementation assay. CONCLUSIONS/SIGNIFICANCE: These results show that the orientation of the Ca(v)beta subunit relative to the alpha(1)2.2 subunit is critical, and suggests additional points of contact between these subunits are required for Ca(v)beta to regulate channel activity

Implantable Cardiac Defibrillator Pocket Infection Due to a Previously Undescribed Cupriavidus Species▿

The genus Cupriavidus consists of Gram-negative, nonfermenting bacteria most of which are environmental organisms, though some species have been associated with human disease. We report the recovery and identification of an isolate that represents a previously undescribed species of Cupriavidus from an implantable cardiac defibrillator pocket infection

Features of Topography of Trigeminal Ganglion in Prenatal Human Development

У роботі наведені дані, щодо топографії і розмірів трійчастого вузла людини на 16-23 тижнях внутрішньоутробного розвитку. Встановлено, що в досліджуваний період ембріогенезу взаємовідношення трійчастого вузла людини з оточуючими анатомічними утвореннями принципово не відрізняється від такого в постнатальному періоді розвитку. У період з 16 по 23 тиждень ембріогенезу істотно збільшується відстань від трійчастого вузла до верхньої очної щілини і внутрішнього слухового отвору. Також у зазначений період внутрішньоутробного розвитку відбувається збільшення трійчастого вузла, в першу чергу за рахунок поперечного розміру; В работе приведены данные, относительно топографии и размеров тройничного узла человека на 16-23 неделях внутриутробного развития. Установлено, что в изучаемый период эмбриогенеза взаимоотношение тройничного узла человека с окружающими анатомическими образованиями принципиально не отличается от такового в постнатальном периоде развития. В период с 16 по 23 неделю эмбриогенеза существенно увеличивается расстояние от тройничного узла до верхней глазничной щели и внутреннего слухового отверстия. Также в указанный период внутриутробного развития происходит увеличение тройничного узла, в первую очередь за счёт поперечного размера; The article presents the data regarding the size and topography of the human trigeminal ganglion at 16-23 weeks of fetal development. Found that during the study period of embryogenesis relationship of trigeminal ganglion of human with the anatomical structures is not fundamentally different from that in the postnatal development. Between 16 to 23 week of embryogenesis significantly increases the distance from the trigeminal ganglion to the superior orbital fissure and internal acoustic opening. Also in this period of prenatal development is the increase in trigeminal ganglion, primarily due to the transverse size