Fractals are patterns that are self-similar across multiple length-scales. Macroscopic fractals are common in nature; however, so far, molecular assembly into fractals is restricted to synthetic systems. Here we report the discovery of a natural protein, citrate synthase from the cyanobacterium Synechococcus elongatus, which self-assembles into Sierpiński triangles. Using cryo-electron microscopy, we reveal how the fractal assembles from a hexameric building block. Although different stimuli modulate the formation of fractal complexes and these complexes can regulate the enzymatic activity of citrate synthase in vitro, the fractal may not serve a physiological function in vivo. We use ancestral sequence reconstruction to retrace how the citrate synthase fractal evolved from non-fractal precursors, and the results suggest it may have emerged as a harmless evolutionary accident. Our findings expand the space of possible protein complexes and demonstrate that intricate and regulatable assemblies can evolve in a single substitution.
Laboratoire de Recherche: Caractérisations, Applications et Modélisation de Matériaux, Université de Tunis El Manar, Faculté des Sciences de Tunis, Tunis 2092, Tunisia.
This study optimizes immunofluorescence techniques using gold nanoparticles (AuNPs) to improve visualization of endothelial nitric oxide synthase (eNOS) in gill tissue. Two types of AuNP dispersions, stabilized in phosphate buffered saline (PBS) and citrate buffer (CB), were evaluated for their imaging performance. AuNPs suspended in PBS provided significantly better optical contrast due to uniform distribution and effective tissue attachment, whereas citrate-suspended AuNPs exhibited aggregation, resulting in reduced contrast.
Objectives: To examine the effect of the NAD precursor, nicotinic acid (NA), for improving skeletal muscle status in sedentary older people.
Methods: In a double-blind, randomised, placebo-controlled design, 18 sedentary yet otherwise healthy older (65-75 y) males were assigned to 2-weeks of NA (acipimox; 250 mg × 3 daily, n=8) or placebo (PLA, n=10) supplementation. At baseline, and after week 1 and week 2 of supplementation, a battery of functional, metabolic, and molecular readouts were measured.
This study aims to compare the effects and mechanisms of the standard decoction and formula granules of Paeoniae Radix Rubra in regulating the metabolism in the rat model of heat toxin and blood stasis. SD rats were randomized into control, model, standard decoction, and formula granules groups. After 14 days of administration, the rats in the latter three groups were subjected to subcutaneous injection with carrageenan and intraperitoneal injection with bacterial lipopolysaccharide for the modeling of heat toxin and blood stasis.
Mitochondrial dysfunction is a critical factor in the pathogenesis of Alport syndrome (AS), contributing to podocyte injury and disease progression. Ezetimibe, a lipid-lowering drug, is known to inhibit cholesterol and fatty acid uptake and to reduce triglyceride content in the kidney cortex of mice with AS. However, its effects on lipid droplet (LD) utilization by mitochondria have not been explored.
Lipid accumulation is associated with breast cancer metastasis. However, the mechanisms underlying how breast cancer cells increase lipid stores and their functional role in disease progression remain incompletely understood. Herein we quantified changes in lipid metabolism and characterized cytoplasmic lipid droplets in metastatic versus non-metastatic breast cancer cells.
