Mechanical Stretch and PI3K Signaling Link Cell Migration and Proliferation to Coordinate Epithelial Tubule Morphogenesis in the Zebrafish Pronephros

Organ development leads to the emergence of organ function, which in turn can impact developmental processes. Here we show that fluid flow-induced collective epithelial migration during kidney nephron morphogenesis induces cell stretch that in turn signals epithelial proliferation. Increased cell proliferation was dependent on PI3K signaling. Inhibiting epithelial proliferation by blocking PI3K or CDK4/Cyclin D1 activity arrested cell migration prematurely and caused a marked overstretching of the distal nephron tubule. Computational modeling of the involved cell processes predicted major morphological and kinetic outcomes observed experimentally under a variety of conditions. Overall, our findings suggest that kidney development is a recursive process where emerging organ function “feeds back” to the developmental program to influence fundamental cellular events such as cell migration and proliferation, thus defining final organ morphology

Cytoplasmic Carboxypeptidase 5 Regulates Tubulin Glutamylation and Zebrafish Cilia Formation and Function

Glutamylation is a functionally important tubulin posttranslational modification enriched on stable microtubules of neuronal axons, mitotic spindles, centrioles, and cilia. In vertebrates, balanced activities of tubulin glutamyl ligase and cytoplasmic carboxypeptidase deglutamylase enzymes maintain organelle- and cell type-specific tubulin glutamylation pat terns. Tubulin glutamylation in cilia is regulated via restricted subcellular localization or ex pression of tubulin glutamyl ligases (ttlls) and nonenzymatic proteins, including the zebrafish TPR repeat protein Fleer/Ift70. Here we analyze the expression patterns of ccp deglutamy lase genes during zebrafish development and the effects of ccp gene knockdown on cilia formation, morphology, and tubulin glutamylation. The deglutamylases ccp2, ccp5, and ccp6 are expressed in ciliated cells, whereas ccp1 expression is restricted to the nervous system. Only ccp5 knockdown increases cilia tubulin glutamylation, induces ciliopathy phenotypes, including axis curvature, hydrocephalus, and pronephric cysts, and disrupts multicilia motility, suggesting that Ccp5 is the principal tubulin deglutamylase that maintains functional levels of cilia tubulin glutamylation. The ability of ccp5 knockdown to restore cilia tubulin glutamyla tion in fleer/ift70 mutants and rescue pronephric multicilia formation in both fleer- and ift88-deficient zebrafish indicates that tubulin glutamylation is a key driver of ciliogenesis

Collective Epithelial Migration Drives Kidney Repair after Acute Injury

Acute kidney injury (AKI) is a common and significant medical problem. Despite the kidney’s remarkable regenerative capacity, the mortality rate for the AKI patients is high. Thus, there remains a need to better understand the cellular mechanisms of nephron repair in order to develop new strategies that would enhance the intrinsic ability of kidney tissue to regenerate. Here, using a novel, laser ablation-based, zebrafish model of AKI, we show that collective migration of kidney epithelial cells is a primary early response to acute injury. We also show that cell proliferation is a late response of regenerating kidney epithelia that follows cell migration during kidney repair. We propose a computational model that predicts this temporal relationship and suggests that cell stretch is a mechanical link between migration and proliferation, and present experimental evidence in support of this hypothesis. Overall, this study advances our understanding of kidney repair mechanisms by highlighting a primary role for collective cell migration, laying a foundation for new approaches to treatment of AKI

Collective Cell Migration Drives Morphogenesis of the Kidney Nephron

Tissue organization in epithelial organs is achieved during development by the combined processes of cell differentiation and morphogenetic cell movements. In the kidney, the nephron is the functional organ unit. Each nephron is an epithelial tubule that is subdivided into discrete segments with specific transport functions. Little is known about how nephron segments are defined or how segments acquire their distinctive morphology and cell shape. Using live, in vivo cell imaging of the forming zebrafish pronephric nephron, we found that the migration of fully differentiated epithelial cells accounts for both the final position of nephron segment boundaries and the characteristic convolution of the proximal tubule. Pronephric cells maintain adherens junctions and polarized apical brush border membranes while they migrate collectively. Individual tubule cells exhibit basal membrane protrusions in the direction of movement and appear to establish transient, phosphorylated Focal Adhesion Kinase–positive adhesions to the basement membrane. Cell migration continued in the presence of camptothecin, indicating that cell division does not drive migration. Lengthening of the nephron was, however, accompanied by an increase in tubule cell number, specifically in the most distal, ret1-positive nephron segment. The initiation of cell migration coincided with the onset of fluid flow in the pronephros. Complete blockade of pronephric fluid flow prevented cell migration and proximal nephron convolution. Selective blockade of proximal, filtration-driven fluid flow shifted the position of tubule convolution distally and revealed a role for cilia-driven fluid flow in persistent migration of distal nephron cells. We conclude that nephron morphogenesis is driven by fluid flow–dependent, collective epithelial cell migration within the confines of the tubule basement membrane. Our results establish intimate links between nephron function, fluid flow, and morphogenesis

Анализ биологического возраста по черепу ребенка эпохи каменного века с помощью конусно-лучевой компьютерной томографии

Studying of opportunities of the Cone Beam Computed Tomography (CBCT) in an assessment of bone structure and of a tooth formula was an objective for aging of a paleoanthropological finding. Remains of the child of the Stone Age from a cave Staroselye (Crimea) are subjected to examination. Beam research was carried out when using CBCT with individual selection of laying, physics and technology conditions and modes of scanning depending on anatomic accessory and the size of fragments. The images received as a result of CBCT differ in high informational content (from 7.5 to 10.6 pixels/mm), optimum spatial permission, clearness and contrast. The software of CBCT includes parameters and possibility of post-processor processing of images (creation of panoramic, multiplanar and 3D reconstruction). The method allows carrying out the analysis of anthropological material without the need for their destruction that is the extremely important for work with samples of museum collections. Use of a high-informative beam method of CBCT is perspective for the paleoantropological researches.Цель исследования: изучение возможностей конусно-лучевой компьютерной томографии (КЛКТ) в оценке костной структуры, анализе зубной формулы при определении возраста палеоантропологической находки. Экспертизе подвергнуты останки ребенка каменного века из пещеры Староселье (Крым). Лучевое исследование выполнялось при использовании КЛКТ с индивидуальным подбором укладок, физико-технических условий и режимов сканирования в зависимости от анатомической принадлежности и размера фрагментов. Полученные в результате КЛКТ изображения отличаются высокой информативностью (от 7,5 до 10,6 пикселей/мм), оптимальным пространственным разрешением, четкостью и контрастностью. Программное обеспечение КЛКТ включает параметры и возможность постпроцессорной обработки изображений (построение панорамных, мультипланарных и 3D-реконструкций). Метод позволяет проводить анализ антропологического материала без необходимости их разрушения, что крайне важно для работы с образцами музейных коллекций. Использование высокоинформативного лучевого метода исследования КЛКТ является перспективным для палеоантропологических исследований

Interaction of Mutually Perpendicular Magnetic Fields in HTSC

In this article a problem of interaction of the crossed magnetic fields in superconductors is considered. Superconducting materials have nonlinear magnetic properties. It allows using a non-linear magnetic susceptibility for measurement of feeble magnetic fields. We place a wire of superconducting material in a constant parallel uniform magnetic field. Then we let through a wire the alternating current leak. Interaction of mutual and perpendicular variation magnetic fields, with adequate accuracy is described by Ginzburg-Landau's equations. Approximate solution of the written equations is received. The component of a magnetic field parallel to a wire contains a variable component. Frequency of a variable component of the magnetic field is equal to the doubled current frequency. Amplitude of the variable component of the magnetic field is proportional to strength of the constant magnetic field. The experimental installation for research of interaction of mutually perpendicular magnetic fields is created. The cylinder from HTSC of ceramics of the YBa2Cu3O7-x was used as a sensor. Dependence of amplitude of the second harmonica of a variation magnetic field on strength of a constant magnetic field is received

Fluid flow and guidance of collective cell migration

Collective cell migration is emerging as a significant component of many biological processes including metazoan development, tissue maintenance and repair and tumor progression. Different contexts dictate different mechanisms by which migration is guided and maintained. In vascular endothelia subjected to significant shear stress, fluid flow is utilized to properly orient a migrating group of cells. Recently, we discovered that the developing zebrafish pronephric epithelium undergoes a similar response to luminal fluid flow, which guides pronephric epithelial migration towards the glomerulus. Intratubular migration leads to significant changes in kidney morphology. This novel process provides a powerful in vivo model for further exploration of the mechanisms underlying mechanotransduction and collective migration

The Application of Electrophysical Effects in the Processing of Agricultural Materials

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