Luis Bagatolli

Instituto de Investigación Médica Mercedes y Martín Ferreyra-INIMEC (CONICET) -NAtional University of Córdoba Argentina

A partir de la obra Lo normal y lo patológico de Georges Canguilhem, publicada en 1943, se explora cómo las neurociencias definen y legitiman, en la actualidad, la existencia de los rasgos autistas como expresión subclínica de autismo. La hipótesis general del presente trabajo es que en la bibliografía especializada de este ámbito parecen consolida...

Dengue (DENV) and Zika (ZIKV) virus capsid proteins efficiently recruit and surround the viral RNA at the ER membrane to yield nascent viral particles. However, little is known either about the molecular mechanisms by which multiple copies of capsid proteins assemble into nucleocapsids or how the nucleocapsid is recruited and wrapped by the ER memb...

Using LAURDAN fluorescence we observed that water dynamics measured at the interface of DOPC bilayers can be differentially regulated by the presence of crowded suspensions of different proteins (HSA, IgG, Gelatin) and PEG, under conditions where the polymers are not in direct molecular contact with the lipid interface. Specifically, we found that...

Liquid-liquid phase separation is prone to occur when positively charged proteins interact with nucleic acids. Here, we studied biophysical properties of Dengue (DENV) and Zika (ZIKV) virus capsid proteins to understand the process of RNA genome encapsidation. In this route, the capsid proteins efficiently recruit the viral RNA at the ER membrane t...

This paper revisits long-standing ideas about biological membranes in the context of an equally long-standing, but hitherto largely unappreciated, perspective of the cell based on concepts derived from the physics and chemistry of colloids. Specifically, we discuss important biophysical aspects of lipid supramolecular structure to understand how th...

Although inductive effects in organic compounds are known to influence chemical properties such as ionization constants, their specific contribution to the properties/behavior of amino acids and functional groups in peptides remains largely unexplored. In this study we developed a computationally economical algorithm for ab initio calculation of th...

Important concepts from colloidal physical chemistry such as coacervation, phase transitions, emergent properties and ionic association, are currently emerging in the lexicon of cellular biology, prompted mostly by recent experimental observations of liquid phase coexistence in the cell cytosol. Nevertheless, from an historical point of view, the a...

We measured temporal oscillations of intracellular K+ concentration in yeast cells exhibiting glycolytic oscillations using fluorescence spectroscopy and microscopy methods. These oscillations showed the same period as those of glycolytic metabolites (NADH, ATP), indicating a strong coupling between them. We experimentally ruled out that oscillatio...

We propose that active metabolic processes may regulate structural changes in biological membranes via the physical state of cell water. This proposition is based on recent results obtained from our group in yeast cells displaying glycolytic oscillations, where we demonstrated that there is a tight coupling between the oscillatory behavior of glyco...

Two dimensional phase separation in lipid membranes and cell membranes is of interest to biology because of the idea of membrane rafts - compositionally heterogeneous liquid crystal domains with cellular functions. Few quantitative tools exist for characterizing and differentiating coexisting phases on a molecular scale. Lipid acyl chain order can...

We have established how natural compounds from green propolis collected by the species Apis mellifera act against the growth of Pythium aphanidermatum. On the basis of mass spectrometry (Q-ToF MS), we determined that Artepillin C, the major constituent of green propolis, underlies the effect and displays activity against P. aphanidermatum at a mini...

Water is involved in all aspects of biological activity, both as a solvent and as a reactant. It is hypothesized that intracellular water is in a highly structured state due to the high concentrations of macromolecules in the cell and that this may change the activity of intracellular enzymes due to altered binding affinities and allosteric regulat...

We measured temporal oscillations in thermodynamic variables such as temperature, heat flux, and cellular volume in suspensions of non-dividing yeast cells which exhibit temporal glycolytic oscillations. Oscillations in these variables have the same frequency as oscillations in the activity of intracellular metabolites, suggesting strong coupling b...

Lipid vesicles are supramolecular structures of great interest for industrial and research applications. They can be used simply to compartmentalize solutions and pack active molecules in femtoliter-scale volumes or as highly sophisticated drug delivery vehicles and dynamic cell-size bioreactors. For these reasons, many methods for the production o...

We explored the dynamic coupling of intracellular water with metabolism in yeast cells. Using the polarity-sensitive probe 6-acetyl-2-dimethylaminonaphthalene (ACDAN), we show that glycolytic oscillations in the yeast S. cerevisiae BY4743 wild-type strain are coupled to the generalized polarization (GP) function of ACDAN, which measures the physica...

We compared the lateral structure of giant unilamellar vesicles (GUVs) composed of three pseudo binary mixtures of different glycosphingolipid (GSL), i.e. sulfatide, asialo-GM1 or GM1, with POPC. These sphingolipids possess similar hydrophobic residues but differ in the size and charge of their polar head group. Fluorescence microscopy experiments...

Atomic force microscopy (AFM) is one of the most commonly used scanning probe microscopy techniques for nanoscale imaging and characterization of lipid-based particles. However, obtaining images of such particles using AFM is still a challenge. The present study extends the capabilities of AFM to the characterization of proteoliposomes, a special c...

For logistic and practical reasons, it is difficult to perform in vitro studies on percutaneous penetration on fresh human skin obtained directly from surgery. Skin samples are therefore often kept frozen until use. The present chapter presents the available literature on the topic. Storage of human skin at −20 °C causes structural changes in the u...

Higher sterols are universally present in large amounts (20-30%) in the plasma membranes of all eukaryotes whereas they are universally absent in prokaryotes. It is remarkable that each kingdom of the eukaryotes has chosen, during the course of evolution, its preferred sterol: cholesterol in animals, ergosterol in fungi and yeast, phytosterols in h...

Background: Mitochondrial Creatine kinase (mtCK) is highly abundant in mitochondria; its quantity is equimolecular to the Adenylic Nucleotide Translocator and represents 1% of the mitochondrial proteins. It is a multitask protein localized in the mitochondria intermembrane space where it binds to the specific cardiolipin (CL) phospholipid. If mtCK...

We introduce a custom-built instrument designed to perform fast LAURDAN Generalized Polarization (GP) imaging on planar supported membranes. It is mounted on a widefield fluorescence microscope and allows kinetic analysis of the GP function in the millisecond time scale, largely improving the temporal resolution previously achieved using laser scan...

Recent results from our laboratory support the view that the intracellular milieu cannot be treated as a homogeneous dilute system and, more importantly, reveal for the first time a dynamical coupling between intracellular water and an active metabolic process involving fluctuations in ATP concentration. These results are difficult to understand in...

The dimensions of a lipid molecule is determined by several factors. Firstly, there are obvious geometric factors like the size of the polar head, the length of the fatty acid tail, and the degree of unsaturation of the fatty-acid chains. In Fig. 4.1 are shown examples where the molecules are inscribed by cylinders. Obviously, the longer the fatty...

We often tacitly assume that useful devices have to be made of materials that are hard and solid in order to be tough, durable, and functionally reliable. A house, a car, and a computer are excellent examples. Although lipids and other soft materials can be used as templates for producing certain types of hard materials, we would not use the full p...

Some of the most fascinating and spectacular events in Nature arise when the matter changes state. Soft matter like lipid bilayers and membranes have their share of these phenomena. Lets us, however, start with a simple and well-known example, water. Water in the form of ice melts upon heating into liquid water which upon further heating turns into...

So far and in particular in Chap. 6 we considered membranes as ultra thin shells where the internal membrane structure only entered very indirectly through the spontaneous curvature, through the observation that a bilayer consists of two monolayers , and by the simple fact that the membrane has a finite thickness . In order to understand the organi...

A large number of pharmacologically active drugs are hydrophobic or amphiphilic compounds suggesting that their targets in the body are hydrophobic sites or at hydrophobic-hydrophilic interfaces . The hydrophobic sites could be either proteins and receptors or the interior of cellular membranes. The interfaces could be surfaces of membranes. In any...

The physical constraint imposed on integral membrane proteins by the lipid bilayer thickness as illustrated in Fig. 13. 4 suggests that a mechanical hydrophobic matching principle may be operative. Hydrophobic matching means that the hydrophobic length of the trans-membrane domain is matched to the hydrophobic thickness of the lipid bilayer. There...

It has been intensively discussed whether lipid phase transitions have any bearing on biological phenomena, and there are conflicting opinions concerning this question . The viewpoint to be advocated here is that lipid phase transitions as such are unlikely to be of direct relevance for most membrane functions. They are simply not robust enough to...

Cholesterol was discovered in 1815 by the French chemist Michel E. Chevreul who found it in human gall stones . Its precise molecular structure , shown in Fig. 2. 9a remained however unknown until 1932. In the following decades the biosynthetic pathway to cholesterol was worked out, and during the 1970 s and 1980s the relationship between the molec...

Water is necessary for life of the form we know. In fact it is so essential that when NASA goes into space and looks for signs of extra-terrestrial life , the search is concentrated on water and features of planetary surfaces which may reflect that water is present or has been present. Moreover, it is mandatory for the evolution of life and mainten...

It is instructive to consider the spatial dimensions of a membrane system like a uni-lamellar vesicle as shown in Fig. 3. 5. Whereas the lipid bilayer itself is only about 5 nm thick, the diameter of vesicles and liposomes is orders of magnitude larger, typically in the range from 50 to 50,000 nm. Hence, lipid bilayers are extremely thin films of t...

Living organisms are divided into three kingdoms, the eukaryotes , the eubacteria , and the archaebacteria . The eubacteria and the archaebacteria, which among themselves differ as much as they do from eukaryotes, are conventionally grouped together as prokaryotes . The bacteria common to most people, e.g., E. coli bacteria or the bacteria in sour...

We are used to study processes and structures in Nature as three-dimensional phenomena. Lipid bilayers and biological membranes also live in three-dimensional space. As pointed out and described in Chap. 6, membranes, due to their incredible small thickness compared to their extension, are in many respects like two-dimensional systems imbedded in a...

Fluorescence spectroscopy is a powerful experimental tool used by scientists from many disciplines. During the last decades there have been important developments on distinct fluorescence methods, particularly those related to the study of biological phenomena. This chapter discusses the foundations of the fluorescence phenomenon, introduces some g...

Using LAURDAN spectral imaging and spectral phasor analysis we concurrently studied the growth and hydration state of subcellular organelles (Lamellar Body-like, LB-like) from live A549 lung cancer cells at different post-confluence days. Our results reveal a time dependent two-step process governing the size and hydration of these intracellular LB...

As Gregorio Weber anticipated in his seminal 1979 article, 6-acyl-2-(dimethylamino)naphthalene probes became excellent tools to study nanosecond relaxation processes of biological systems. Examples are the use of PRODAN (or DANCA) to study relaxation of specific protein matrixes, or LAURDAN (as well as PRODAN) extensively used to study the extent o...

We have reconstituted functional Na +/K +-ATPase (NKA) into giant unilamellar vesicles (GUVs) of well-defined binary and ternary lipid composition including cholesterol. The activity of the membrane system can be turned on and off by ATP. The hydrolytic activity of NKA is found to depend on membrane phase, and the water relaxation in the membrane o...

Background and purpose: We tested the hypothesis that in resistance arteries from cardiovascular disease patients, effects of an endothelium-dependent vasodilator depend on the contractile stimulus. Experimental approach: Arteries dissected from parietal pericardium of cardiothoracic surgery patients were studied by myography and imaging techniq...

For logistic and practical reasons, it is difficult to perform in vitro studies on percutaneous penetration on fresh human skin obtained directly from surgery. Skin samples are therefore often kept frozen until use. The present chapter presents the available literature on the topic. Storage of human skin at −20 °C causes structural changes in the u...

Oils and fats refer to a large and diverse group of compounds that do not easily dissolve in water . There is no strict distinction between oils and fats; fats usually refer to materials like wax , lard , and butter that are solid at room temperature, whereas oils like olive oil and fish oil are liquid. As is well known, butter can melt upon heatin...

Proteins are the workhorses of the cell . They are involved at almost every stage of biological activity. Some of the proteins are enzymes that facilitate biochemical processes. Others are little motor molecules that make our muscles work. Still others take care of communication and transport of energy and matter. Proteins come in many different si...

Being many molecules together in a bilayer membrane, the lipids act socially as described above in Chap. 9 and organize laterally in the plane of the bilayer in a non-random and non-uniform fashion. In contrast to the trans-bilayer structure described in Chap. 8, the lateral bilayer structure and its molecular organization are less well characteriz...

A model is an abstraction of Nature. It can be very concrete and practical, e.g., given by a protocol to construct a particular sample for experimental investigation, or it can be given by a precise mathematical formula that lends itself to a theoretical calculation. A model can also be less well-defined and sometimes even implicit in the mind of t...

Biological matter like membranes are soft materials. Soft materials have a number of unusual properties that are very different from those of traditional hard materials such as metals, ceramics, semi-conductors, and composites. Lipid membranes are soft because they are basically structured liquids made of molecules with substantial conformational c...

The skin is our largest organ and anatomically one of the most heterogeneous. Its presence and function are usually taken for granted, and few of us wonder why we are not dissolved and flushed down the drain when we take a shower. We tend to think of the skin as an organ that is inferior to other organs like the heart, the brain, and the liver. How...

There is a constant turnover of lipids when a cell or an organism performs its life functions. Lipids have to be molecularly remodeled in order to meet the needs of a particular cell or tissue type, lipids have to be broken down to fatty acids and mono-acylglycerols in order to be able to be transported across membranes, and lipids have to be expor...

You are what you eat. Many of the molecular building blocks that our body is made of are supplied from the diet. Our food consists of protein, sugar, and fat (in addition to a lot of important minerals). These food molecules are broken down, e.g., to amino acids and fatty acids, and put together again to produce precisely the kind of proteins and l...

The present book gives a multi-disciplinary perspective on the physics of life and the particular role played by lipids (fats) and the lipid-bilayer component of cell membranes. The emphasis is on the physical properties of lipid membranes seen as soft and molecularly structured interfaces. By combining and synthesizing insights obtained from a var...

The present book gives a multi-disciplinary perspective on the physics of life and the particular role played by lipids (fats) and the lipid-bilayer component of cell membranes. The emphasis is on the physical properties of lipid membranes seen as soft and molecularly structured interfaces. By combining and synthesizing insights obtained from a var...

Giant Unilamellar Vesicles (GUVs) are simple model membrane systems of cell-size, which are instrumental to study the function of more complex biological membranes involving heterogeneities in lipid composition, shape, mechanical properties, and chemical properties. We have devised a method that makes it possible to prepare a uniform sample of tern...

http://www.rri.res.in/Colloids/newcolloidsmeeting_program.html http://www.rri.res.in/Colloids/Registered_participants_with_poster_titles_Colloids_Meet_2015.pdf

Peripheral vascular resistance is increased in essential hypertension. This involves structural changes of resistance arteries and stiffening of the arterial wall, including remodeling of the extracellular matrix. We hypothesized that biopsies of the human parietal pericardium, obtained during coronary artery bypass grafting or cardiac valve replac...

We detected very strong coupling between the oscillating concentration of ATP and the dynamics of intracellular water during glycolysis in Saccharomyces cerevisiae. Our results indicate that: i) dipolar relaxation of intracellular water is heterogeneous within the cell and different from dilute conditions, ii) water dipolar relaxation oscillates wi...

All biological membranes consist of a complex composite of macromolecules and macromolecular assemblies, of which the fluid lipid-bilayer component is a core element with regard to cell encapsulation and barrier properties. The fluid lipid bilayer also supports the functional machinery of receptors, channels and pumps that are associated with the m...

We have mapped the morphology and orientation of the Na/K ATPase inside model membranes and made a detailed quantifications of the membrane lateral structure. Further work to characterize the lateral organization and function of the pump in membranes and vice-versa, is in progress.

The pulmonary surfactant is organized at the intracellular level in structures known as lamellar bodies (LBs). These subcellular acidic organelles have a variable size (aprox. 0.5-3 um) and based on the electron microscopy data it is proposed that they possess a concentrically membrane lamellar structure. Although the process of LB secretion by phy...

A family of polarity sensitive fluorescent probes (2-(dimethylamino)-6-acylnaphtalenes, i.e. LAURDAN, PRODAN, ACDAN) was introduced by Gregorio Weber in 1979, with the aim to monitor solvent relaxation phenomena on protein matrices. In the following years, however, PRODAN and particularly LAURDAN, were used to study membrane lateral structure and a...

11th International Symposium on FXYD Proteins, Sandberg Estate, Aarhus University, Denmark, September 5-7 (2014).

http://biomembrane-days-2014.mpikg.mpg.de/ Biomembrane Days 2014 September 1-3, Harnack Haus, Berlin Presenting author: Tripta Bhatia Poster no. 8.

This chapter reviews some of the results that have been obtained in our laboratories with regard to characterization of lateral order in model bilayer membranes as well as biological membranes, with particular focus on membrane domains in the submicron regime. The results are based mainly on fluorescence microscopy and two-photon laser scanning mic...

http://www.lrdcopenhagen2014.org/

Cell Membrane Nanodomains: From Biochemistry to Nanoscopy describes recent advances in our understanding of membrane organization, with a particular focus on the cutting-edge imaging techniques that are making these new discoveries possible. With contributions from pioneers in the field, the book explores areas where the application of these novel...

This manuscript discusses basic methodological aspects of optical microscopy and micromanipulation methods to study membranes and reviews methods to generate giant unilamellar vesicles (GUVs). In particular, we focus on the use of fluorescence microscopy and micropipette manipulation techniques to study composition-structure-property materials rela...

https://www.grc.org/programs.aspx?id=14336 Presenting author: Adam C. Simonsen

https://www.grc.org/programs.aspx?id=14336 Presenting author: Tripta Bhatia

We devise a methodology to fixate and image dynamic fluid domain patterns of giant unilamellar vesicles (GUVs) at sub-optical length scales. Individual GUVs are rapidly transferred to a solid support forming planar bilayer patches. These are taken to represent a fixated state of the free standing membrane, where lateral domain structures are kineti...

The term ‘gastrophysics’ has been proposed to describe an emerging scientific discipline that employs an arsenal of the most powerful theoretical, simulational, and experimental techniques from the physical sciences to study the empirical world of cooking and gastronomy. In the same way that biology has inspired the field of biophysics, gastronomy...

Phosphatidylinositol (4,5) bisphosphate (PIP2) is an important signaling molecule located on the inner leaflet of the cell membrane. In order to perform its various signaling functions, it is suggested that PIP2 must be able to form localized clusters. In this study, we have used LAURDAN generalized polarization function (GP) with unlabeled PIP2 an...

The structure, dynamics, and stability of lipid bilayers are controlled by thermodynamic forces, leading to overall tensionless membranes with a distinct lateral organization and a conspicuous lateral pressure profile. Bilayers are also subject to built-in curvature-stress instabilities that may be released locally or globally in terms of morpholog...

Understanding the structural and dynamical features of skin is critical for advancing innovation in personal care and drug discovery. Synthetic detergent mixtures used in commercially available body wash products are thought to be less aggressive towards the skin barrier when compared to conventional detergents. The aim of this work is to comparati...

This work comprises a structural and dynamical study of monolayers and bilayers composed of native pulmonary surfactant from mice. Spatially resolved information was obtained using fluorescence (confocal, wide field and two photon excitation) and atomic force microscopy methods. Lipid mass spectrometry experiments were also performed in order to ob...