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Red blood cells (RBCs), also referred to as red cells, red blood corpuscles (in humans or other animals not having nucleus in red blood cells), haematids, erythroid cells or erythrocytes (from Greek erythros 'red' and kytos 'hollow vessel', with -cyte translated as 'cell' in modern usage), are the most common type of blood cell and the vertebrate's principal means of delivering oxygen (O2) to the body tissues—via blood flow through the circulatory system. RBCs take up oxygen in the lungs, or in fish the gills, and release it into tissues while squeezing through the body's capillaries. The cytoplasm of a red blood cell is rich in hemoglobin, an iron-containing biomolecule that can bind oxygen and is responsible for the red color of the cells and the blood. Each human red blood cell contains approximately 270 million hemoglobin molecules. The cell membrane is composed of proteins and lipids, and this structure provides properties essential for physiological cell function such as d

Proteins interacting with PfEMP1 in P. falciparum infected erythrocyte

Damien Jacot

During infection in humans, P. falciparum invades and refurbishes the red blood cells (RBCs) in order to persist and proliferate. Parasite survival depends on expression of a parasite encoded cytoadherence ligand at the surface of the infected RBC called PfEMP1 (P. falciparum erythrocyte membrane protein 1). PfEMP1 comprises a N-terminal extracellular part, which mediates binding to receptors at the host endothelium. It also contains a C-terminal part which is conserved among all PfEMP1 molecules. This acidic terminal segment (ATS) anchors PfEMP1 to the membrane of infected RBCs and has a role for trafficking. To bring proteins to the RBC surface, P. falciparum builds its own trafficking machinery de novo since the erythrocytes do not contain secretory organelles. These new structures include parasite derived compartments called Maurer's clefts (MCs) located at the RBC periphery. The resident MCs protein MAHRP1 (membrane-associated histidine-rich protein 1) has been shown to be critical for PfEMP1 trafficking. A MAHRP1 KO strain had no PfEMP1 on the RBC surface but accumulated PfEMP1 within the parasite. MAHRP1 is a 28.9kDa protein with 249 amino acids containing a N-terminal, a transmembrane, and a C-terminal domain comprising histidine-rich repeats. To re-establish PfEMP1 trafficking, the MAHRP1 KO parasite line was complemented with various truncated HA-tagged fragments of MAHRP1. Immunofluorescent assays (IFAs) showed that the Cterminal domain with the histidine-rich repeats was not essential for PfEMP1 trafficking.

{MAHRP1}_{1-130}

and

{MAHRP1}_{1-169}

were exported to MCs and restored trafficking of PfEMP1. Shorter MAHRP1 fragments were not exported to MCs and PfEMP1 transport remained impaired. New transfection constructs were designed including the C-terminal part to identify important domain(s) of MAHRP1 for PfEMP1 trafficking. To identify other proteins interacting with PfEMP1, the ATS domain of PfEMP1 was recombinantly expressed and used in pull-down experiments. In these experiments using parasite lysates, PF14_0377 was identified as a potential interaction partner. This protein has been described as putative, vesicular-associated membrane protein. To subsequently assess the interaction(s) and the localization(s), PF14_0377 was cloned and transfected in 3D7 for IFAs. Due to time restrictions all these new transfectants could not be analyzed completely

2009

Modelling the Intracellular Environment under Uncertainty, from Post-translational Modification to Metabolic Networks

Robin Alexander Denhardt-Eriksson

Modelling and analysis of biological systems is crucial in order to quantitatively explain and predict their behaviour. The importance of modelling in systems biology becomes even more evident when tackling complex, large systems. Approaches that rely on modelling can be used to tackle a range of problems, such as cellular signalling or using genetically modified bacteria to synthesize human proteins for medical purposes. These phenomena range across different spatiotemporal scales, whether it is predicting the decay of red blood cells for blood transfusion or finding engineering targets in order to increase the productivity of bioprocesses. Reconciling models with experimental data and quantifying how uncertainty propagates through these models is crucial to exploiting them to their full potential. Uncertainty impacts not only the calibration and validation of a model, but also the predictions extracted from it. Developing and implementing uncertainty quantification methods into these models is a key step in exploring their behaviour and accelerating the adoption of such methods in metabolic engineering. In this thesis I firstly propose to implement and explore uncertainty quantification methods on control coefficients obtained by Metabolic Control Analysis (MCA) of Genome Scale Metabolic Models (GEMs), with the goal of quantifying uncertainty propagation from model parameters to control coefficients. I additionally want to build Single Protein Models that describe the effects of Post Translational Modifications (PTMs). The nature of the experimental data available to calibrate these models makes uncertainty an inherent property, and therefore Global Sensitivty Analysis (GSA) techniques are well suited to describing the links between parameter uncertainty and model behaviour.

EPFL2021

Red Blood Cell Aging During Storage, Studied Using Optical Tweezers Experiment

Sylvia Jeney, Hanieh Mohammadi

This paper presents experimental and numerical studies of erythrocyte stretching, with a focus on the aging of red blood cells in an in vitro environment during storage. The experimental studies were performed using optical tweezers. The laser beam was used to pull and stretch a cell sedimented on a flat surface. A force calibration was obtained via a comparison of the experimental data with results from finite element simulations of the cell stretching. The experiments were performed using blood samples from blood bank donations made by three donors. The experiments were performed over 21 days of storage, and the estimate erythrocyte membrane shear modulus during this period increased from 2.5 to 13 mu N/m.

Springer2015

Proteins interacting with PfEMP1 in P. falciparum infected erythrocyte

Damien Jacot

{MAHRP1}_{1-130}

and

{MAHRP1}_{1-169}

2009