1,720,991 research outputs found
Light energy transduction in liposome-based artificial cells
Full text linkIn this work we review the latest strategies for the bottom-up assembly of energetically autonomous artificial cells capable of transducing light energy into chemical energy and support internalized metabolic pathways. Such entities are built by taking inspiration from the photosynthetic machineries found in nature which are purified and reconstituted directly in the membrane of artificial compartments or encapsulated in form of organelle-like structures. Specifically, we report and discuss recent examples based on liposome-technology and multi-compartment (nested) architectures pointing out the importance of this matter for the artificial cell synthesis research field and some limitations and perspectives of the bottom-up approach
Novel directions in molecular systems design: The case of light-transducing synthetic cells
No full textImportant progresses have been achieved in the past years in the field of bottom-up synthetic biology, especially aiming at constructing cell-like systems based on lipid vesicles (liposomes) entrapping both biomolecules or synthetic compounds. These âsynthetic cellsâ mimic the behaviour of biological cells but are constituted by a minimal number of components. One key aspect related to this research is the energetic needs of synthetic cells. Up to now, high-energy compounds have been given in order to drive biochemical reactions inside the vesicle lumen. In order to be autonomous, synthetic cells must produce their own biochemical energy from available energy sources. At this aim we started a long-term research program focused on the construction of photoautotrophic synthetic cells, starting with the reconstitution, in active and highly oriented form, of the photosynthetic reaction centre in giant lipid vesicles (Altamura et al., PNAS 2017, 114, 3837â3842). Here we comment this first milestone by showing the synthetic biology context wherein it is developed, the future steps, and the experimental approach that might allow such an achievement
The Rise of the Nested Multicompartment Model in Synthetic Cell Research
Full text linkThe Rise of the Nested Multicompartment Model in Synthetic Cell Researc
Recent Theoretical Approaches to Minimal Artificial Cells
No full textMinimal artificial cells (MACs) are self-assembled chemical systems able to mimic the behavior of living cells at a minimal level, i.e. to exhibit self-maintenance, self-reproduction and the capability of evolution. The bottom-up approach to the construction of MACs is mainly based on the encapsulation of chemical reacting systems inside lipid vesicles, i.e. chemical systems enclosed (compartmentalized) by a double-layered lipid membrane. Several researchers are currently interested in synthesizing such simple cellular models for biotechnological purposes or for investigating origin of life scenarios. Within this context, the properties of lipid vesicles (e.g., their stability, permeability, growth dynamics, potential to host reactions or undergo division processes…) play a central role, in combination with the dynamics of the encapsulated chemical or biochemical networks. Thus, from a theoretical standpoint, it is very important to develop kinetic equations in order to explore first—and specify later—the conditions that allow the robust implementation of these complex chemically reacting systems, as well as their controlled reproduction. Due to being compartmentalized in small volumes, the population of reacting molecules can be very low in terms of the number of molecules and therefore their behavior becomes highly affected by stochastic effects both in the time course of reactions and in occupancy distribution among the vesicle population. In this short review we report our mathematical approaches to model artificial cell systems in this complex scenario by giving a summary of three recent simulations studies on the topic of primitive cell (protocell) systems
Photosynthesis Without the Organisms: The Bacterial Chromatophores
No full textAnoxygenic photosynthetic bacteria are an extremely old form of life that inhabits planet Earth since approximately 3 Gya. They represent the model system for the far more complex photosynthetic organisms appeared later in time, i.e. cyanobacteria, algae and plants, and capable of performing the oxygenic photosynthesis. In this chapter we wish to present a short review of the cell architecture of one specific phototrophic bacterium, namely Rhodobacter sphaeroides, devoting particular attention to cytoplasmic membrane and its invagination originating under anoxygenic conditions and exposure to light. The structure and enzyme organization of the so-called chromatophores of two strains of Rhodobacter sphaeroides are presented, along with the isolation and purification procedures
Screening Readthrough Compounds to Suppress Nonsense Mutations: Possible Application to β-Thalassemia
Full text linkSeveral types of thalassemia (including beta(0)39-thalassemia) are caused by nonsense mutations in genes controlling globin production, leading to premature translation termination and mRNA destabilization mediated by the nonsense mediated mRNA decay. Drugs (for instance, aminoglycosides) can be designed to suppress premature translation termination by inducing readthrough (or nonsense suppression) at the premature termination codon. These findings have introduced new hopes for the development of a pharmacologic approach to cure this genetic disease. In the present review, we first summarize the principle and current status of the chemical relief for the expression of functional proteins from genes otherwise unfruitful for the presence of nonsense mutations. Second, we compare data available on readthrough molecules for beta(0)-thalassemia. The examples reported in the review strongly suggest that ribosomal readthrough should be considered as a therapeutic approach for the treatment of beta(0)-thalassemia caused by nonsense mutations. Concluding, the discovery of molecules, exhibiting the property of inducing beta-globin, such as readthrough compounds, is of great interest and represents a hope for several patients, whose survival will depend on the possible use of drugs rendering blood transfusion and chelation therapy unnecessary
Table-top combined scanning X-ray small angle scattering and transmission microscopies of lipid vesicles dispersed in free-standing gel
No full textA mm thick free-standing gel containing lipid vesicles made of 2-oleoyl-1-palmitoyl-sn-glycero-3-
phosphocholine (POPC) was studied by scanning Small Angle X-ray Scattering (SAXS) and X-ray
Transmission (XT) microscopies. Raster scanning relatively large volumes, besides reducing the risk of
radiation damage, allows signal integration, improving the signal-to-noise ratio (SNR), as well as high
statistical significance of the dataset. The persistence of lipid vesicles in gel was demonstrated, while
mapping their spatial distribution and concentration gradients. Information about lipid aggregation and
packing, as well as about gel density gradients, was obtained. A posteriori confirmation of lipid presence
in well-defined sample areas was obtained by studying the dried sample, featuring clear Bragg peaks
from stacked bilayers. The comparison between wet and dry samples allowed it to be proved that lipids
do not significantly migrate within the gel even upon drying, whereas bilayer curvature is lost by
removing water, resulting in lipids packed in ordered lamellae. Suitable algorithms were successfully
employed for enhancing transmission microscopy sensitivity to low absorbing objects, and allowing full
SAXS intensity normalization as a general approach. In particular, data reduction includes normalization
of the SAXS intensity against the local sample thickness derived from absorption contrast maps. The
proposed study was demonstrated by a room-sized instrumentation, although equipped with a high
brilliance X-ray micro-source, and is expected to be applicable to a wide variety of organic, inorganic,
and multicomponent systems, including biomaterials. The employed routines for data reduction and
microscopy, including Gaussian filter for contrast enhancement of low absorbing objects and a region
growing segmentation algorithm to exclude no-sample regions, have been implemented and made
freely available through the updated in-house developed software SUNBIM
Giant Vesicles as Micro-Sized Enzymatic Reactors: Perspectives and Recent Experimental Advancements
No full textSynthetic cells can be constructed by encapsulating an appropriate set of molecules inside lipid vesicles (liposomes). They can be used as primitive cell model or for biotechnological applications. At these aims, it is important to develop experimental methods for liposome formation, solute encapsulation, and solute exchange across the lipid membrane. Here we focus on (i) the encapsulation of a polymer-enzyme (peroxidase) conjugate inside giant vesicles (GVs) prepared from phospholipids, and its reaction with Amplex Red reagent; and (ii) on the formation of amphotericin B pores allowing the entrance of cobalt ions inside calcein-containing vesicles, with the aim of developing experimental methods for constructing cell-like systems capable of processing chemicals. The presented approach is also shortly discussed from the viewpoint of chemical computing
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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