The biomechanical role of overall-shape transformation in a primitive multicellular organism: A case study of dimorphism in the filamentous cyanobacterium Arthrospira platensis

Abstract

Morphological transformations in primitive organisms have long been observed; however, its biomechanical roles are largely unexplored. In this study, we investigate the structural advantages of dimorphism in Arthrospira platensis, a filamentous multicellular cyanobacterium. We report that helical trichomes, the default shape, have a higher persistence length (Lp), indicating a higher resistance to bending or a large value of flexural rigidity (kf), the product of the local cell stiffness (E) and the moment of inertia of the trichomes’ cross-section (I). Through Atomic Force Microscopy (AFM), we determined that the E of straight and helical trichomes were the same. In contrast, our computational model shows that I is greatly dependent on helical radii, implying that trichome morphology is the major contributor to kf variation. According to our estimation, increasing the helical radii alone can increase kf by 2 orders of magnitude. We also observe that straight trichomes have improved gliding ability, due to its structure and lower kf. Our study shows that dimorphism provides mechanical adjustability to the organism and may allow it to thrive in different environmental conditions. The higher kf provides helical trichomes a better nutrient uptake through advection in aquatic environments. On the other hand, the lower kf improves the gliding ability of straight trichomes in aquatic environments, enabling it to chemotactically relocate to more favorable territories when it encounters certain environmental stresses. When more optimal conditions are encountered, straight trichomes can revert to their original helical form. Our study is one of the first to highlight the biomechanical role of an overall-shape transformation in cyanobacteria.

Monitoring of Spirulina Flakes and Powders from Italian Companies

“…When, in a culture of a helically coiled strain, a few filaments happen to become straight, they tend to become predominant [ 38 , 39 ]. Environmental factors, mainly temperature, physical and chemical conditions, may affect the trichome geometry, and several studies consider straight trichomes to be a symptomatic feature of crops grown under stressful conditions, which are associated with slowed metabolism [ 40 ].…”

In Vitro Preparation and Evaluation of Chitosan/Pluronic F-127 Hydrogel as a Local Delivery of Crude Extract of Phycocyanin for Treating Gingivitis

“…Two crude extracts of phycocyanins (PC) were prepared at the Institute of Agricultural Technology, Suranaree University of Technology. Herein, the crude extracts PC were prepared from Arthrospira platensis stain C005H (wild-type spirulina, helical trichomes) and Arthrospira platensis stain C005L (straight trichomes) by ultrasonic -assisted extraction method (Chaiyasitdhi et al, 2018). C005H strain was generously provided by Applied Algal Research Laboratory, Faculty of Science, Chiang Mai University.…”

Protein, phycocyanin, and polysaccharide production by Arthrospira platensis grown with LED light in annular photobioreactors

“…Enomoto et al (2020) reported for Arthrospira that the formation of clumps, that assume the shape of the containing vessel (Ohmori et al 1998), is stimulated by cyclic adenosine monophosphate (cAMP), which is correlated to an increase of respiration and trichome motility; cAMP signaling is also probably regulated by light (Ohmori and Okamoto 2004). In addition, straight trichomes seem to improve directionality and speed of gliding motility (Chaiyasitdhi et al 2018). Ohmori et al (1992) suggested that cAMP might stimulate extracellular polysaccharide production, which is directly involved in cell aggregation.…”