Biology subjects

Livne, A.

Publications and source records attributed to Livne, A..

4 recordsLinked to original sources

bioRxiv2025

3D-Feedy: An open and portable membrane feeder for mosquito research

Female mosquitoes must feed on blood to produce eggs, a natural behavior that also drives disease transmission. Vector biology research and the development of novel control tools depend on reliable methods for blood feeding of laboratory-reared mosquitoes. Artificial membrane feeders have provided a practical alternative to live animals for decades. However, commercial systems are typically expensive, difficult to repair and are tethered to external water baths or bench-top power supplies. Their limited capacity, usually only a few cages at once, further restricts their use, making them impractical in field settings or large insectaries where dozens of experimental crosses must be fed daily. Here we describe 3D-Feedy, an open-hardware, inexpensive membrane feeder that delivers electrically heated membrane feeding using simple, readily available parts. Powered via USB-C, including smartphone powerbanks, it is portable and straightforward to assemble with only basic tools and skills. In direct comparison with the widely used Hemotek feeder in Anopheles gambiae and Aedes albopictus, the 3D-Feedy achieved equal or higher feeding rates and significantly greater egg production while maintaining comparable larval hatching rates. These results validate 3D-Feedy as a practical and accessible tool for mosquito rearing and experimental studies. All design files and instructions are provided as open hardware resources.

zoology↗

bioRxiv2022

Cellular orientational fluctuations, rotational diffusion and nematic order under periodic driving

The ability of living cells to sense the physical properties of their microenvironment and to respond to dynamic forces acting on them plays a central role in regulating their structure, function and fate. Of particular importance is the cellular sensitivity and response to periodic driving forces in noisy environments, encountered in vital physiological conditions such as heart beating, blood vessels pulsation and breathing. Here, we first test and validate two predictions of a mean-field theory of cellular reorientation under periodic driving, which combines the minimization of cellular anisotropic elastic energy with active remodeling forces. We then extend the mean-field theory to include uncorrelated, additive nonequilibrium fluctuations, and show that the theory quantitatively agrees with the experimentally observed stationary probability distributions of the cell body orientation, under a range of biaxial periodic driving forces. The fluctuations theory allows to extract the dimensionless active noise amplitude of various cell types, and consequently their rotational diffusion coefficient. We then focus on intra-cellular nematic order, i.e. on orientational fluctuations of actin stress fibers around the cell body orientation, and show experimentally that intra-cellular nematic order increases with both the magnitude of the driving forces and the biaxiality strain ratio. These results are semi-quantitatively explained by applying the same cell body fluctuations theory to orientationally correlated actin stress fiber domains. The implications of these findings, which make the quantitative analysis of cell mechanosensitivity more accessible, are discussed.

cell biology↗

bioRxiv2019

Cellular contractile forces emerge from time and F-actin dependent non-mechanosensitive displacements

Cells ability to apply contractile forces to their environment and to sense its mechanical properties (e.g. rigidity) are among their most fundamental features. Yet, the interrelations between contractility and mechanosensing, in particular whether contractile force generation depends on mechanosensing, are not understood. We use theory and extensive experiments to study the time evolution of cellular contractile forces and show that they are generated by time-dependent actomyosin contractile displacements that are independent of the environments rigidity. Consequently, contractile forces are non-mechanosensitive. We further show that the force-generating displacements are directly related to the evolution of the actomyosin network, most notably to the time-dependent concentration of F-actin. The emerging picture of force generation and mechanosensitivity offers a unified framework for understanding contractility.\n\nOne Sentence SummaryCellular contractile forces are generated by rigidity-independent displacements that are determined by the time evolution of F-actin assembly.

cell biology↗

bioRxiv2017

Conformational states during vinculin unlocking differentially regulate focal adhesion properties

Focal adhesions (FAs) are multi-protein complexes that connect the actin cytoskeleton to the extracellular matrix, via integrin receptors. The growth, stability and adhesive functionality of these structures are tightly regulated by mechanical stress, yet, despite the extensive characterization of the integrin adhesome, the mechanisms underlying FA mechanosensitivity are still poorly understood. One of the key candidates for regulating FA-associated mechanosensing is vinculin, a prominent FA component, which was proposed to possess either closed (\"auto-inhibited\") or open (active) conformations. However, a direct demonstration of the nature of conformational transition between the two states is still absent. In this study we combined multiple structural and biological approaches to probe the transition from auto-inhibited to active conformation, and determine its effects on FA structure and dynamics. We further show here that the closed to open transition requires two sequential steps that can differentially regulate FA growth and stability.

biochemistry↗