Théorie cellulaire

La théorie cellulaire est la théorie centrale et principale de la biologie cellulaire et le fondement le plus reconnu de la biologie en général. Elle a été alimentée par beaucoup d'expériences réalisées depuis le XVIIe siècle. La théorie cellulaire est constituée de trois principes, qui peuvent être résumés comme suit : la cellule est l'unité structurale, l'unité fonctionnelle et l'unité reproductrice du Vivant Dates historiques thumb|Le microscope de Hooke. 1665 : On attribue à Robert Hooke la première description d'une cellule biologique faite à partir de l'observation de végétaux. Hooke décrit en 1665 un œil de mouche et une cellule de liège (dans « Observation XVIII » de Micrographia), qui sont des cellules mortes, vidées de leur contenu. Il est le premier à utiliser le mot « cellule » en 1667 dans son ouvrage Micrographia. 1675 : Antoni van Leeuwenhoek (1632-1723), grâce à ses améliorations du microscope, observe et fait une description détaillée de cellules vivante

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Modelling cell seeding to homogenize cell distribution within scaffold for tissue engineering

Nathanel David Apter

Cell Seeding is a key factor for good regeneration in tissue engineering. In order to ensure uniform tissue regeneration, a system has to be found to distribute cells evenly within the scaffold that will carry them in the body. In this extent, this work try to find an accurate description of compression forced induced suction which is a seeding technique with reported satisfying seeding efficiency. This description will take the form of a numerical model with COMSOL Multiphysics and will allow us to maximize the seeding in terms of homogeneity. In order to find the best possible seeding, strains and velocities of the compression will be further analyzed. The scaffold material properties will also be examined in order to have the best possible material for that kind of applications.

2015

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An Amidase_3 domain-containing N-acetylmuramyl-L-alanine amidase is required for mycobacterial cell division

Ashima Bhaskar, Neeraj Dhar, Dong Li

Mycobacteria possess a multi-layered cell wall that requires extensive remodelling during cell division. We investigated the role of an amidase_3 domain-containing N-acetylmuramyl-L-alanine amidase, a peptidoglycan remodelling enzyme implicated in cell division. We demonstrated that deletion of MSMEG_6281 (Ami1) in Mycobacterium smegmatis resulted in the formation of cellular chains, illustrative of cells that were unable to complete division. Suprisingly, viability in the Delta ami1 mutant was maintained through atypical lateral branching, the products of which proceeded to form viable daughter cells. We showed that these lateral buds resulted from mislocalization of DivIVA, a major determinant in facilitating polar elongation in mycobacterial cells. Failure of Delta ami1 mutant cells to separate also led to dysregulation of FtsZ ring bundling. Loss of Ami1 resulted in defects in septal peptidoglycan turnover with release of excess cell wall material from the septum or newly born cell poles. We noted signficant accumulation of 3-3 crosslinked muropeptides in the Delta ami1 mutant. We further demonstrated that deletion of ami1 leads to increased cell wall permeability and enhanced susceptiblity to cell wall targeting antibiotics. Collectively, these data provide novel insight on cell division in actinobacteria and highlights a new class of potential drug targets for mycobacterial diseases.

Nature Publishing Group2017

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High-resolution cell outline segmentation and tracking from phase-contrast microscopy images

Mark Etienne Ambühl, Charles Brepsant, Jean-Jacques Meister

Accurate extraction of cell outlines from microscopy images is essential for analysing the dynamics of migrating cells. Phase-contrast microscopy is one of the most common and convenient imaging modalities for observing cell motility because it does not require exogenous labelling and uses only moderate light levels with generally negligible phototoxicity effects. Automatic extraction and tracking of high-resolution cell outlines from phase-contrast images, however, is difficult due to complex and non-uniform edge intensity. We present a novel image-processing method based on refined level-set segmentation for accurate extraction of cell outlines from high-resolution phase-contrast images. The algorithm is validated on synthetic images of defined noise levels and applied to real image sequences of polarizing and persistently migrating keratocyte cells. We demonstrate that the algorithm is able to reliably reveal fine features in the cell edge dynamics.

2012

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BIO-221: Cell and developmental biology for engineers

Students will learn essentials of cell and developmental biology, with an emphasis on animal model systems and quantitative approaches.

BIO-105: Cellular biology and biochemistry for engineers

Basic course in biochemistry as well as cellular and molecular biology for non-life science students enrolling at the Master or PhD thesis level from various engineering disciplines. It reviews essential notions necessary for a training in biology-related engineering fields.

BIO-482: Neuroscience: cellular and circuit mechanisms

This course focuses on the cellular mechanisms of mammalian brain function. We will describe how neurons communicate through synaptic transmission in order to process sensory information ultimately leading to motor behavior.

Vie

La vie est un phénomène naturel pour l'instant uniquement observé sur Terre. La vie se manifeste à travers des structures matérielles organisées appelées organismes vivants, ou êtres vivants, reconna

Biologie

La biologie (du grec bios « la vie » et logos, « discours ») est la science du vivant. Elle recouvre une partie des sciences de la nature et de l'histoire naturelle des êtres vivants. La vie se pré

Physiologie

La physiologie (du grec φύσις, phusis, la nature, et λόγος, logos, l'étude, la science) étudie le rôle, le fonctionnement et l'organisation mécanique, physique et biochimique des organismes vivants