tubular structures
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2022 ◽  
Vol 12 ◽  
Author(s):  
Glenn Philippe ◽  
Damien De Bellis ◽  
Jocelyn K. C. Rose ◽  
Christiane Nawrath

Cuticles are specialized cell wall structures that form at the surface of terrestrial plant organs. They are largely comprised lipidic compounds and are deposited in the apoplast, external to the polysaccharide-rich primary wall, creating a barrier to diffusion of water and solutes, as well as to environmental factors. The predominant cuticle component is cutin, a polyester that is assembled as a complex matrix, within and on the surface of which aliphatic and aromatic wax molecules accumulate, further modifying its properties. To reach the point of cuticle assembly the different acyl lipid-containing components are first exported from the cell across the plasma membrane and then traffic across the polysaccharide wall. The export of cutin precursors and waxes from the cell is known to involve plasma membrane-localized ATP-binding cassette (ABC) transporters; however, other secretion mechanisms may also contribute. Indeed, extracellular vesiculo-tubular structures have recently been reported in Arabidopsis thaliana (Arabidopsis) to be associated with the deposition of suberin, a polyester that is structurally closely related to cutin. Intriguingly, similar membranous structures have been observed in leaves and petals of Arabidopsis, although in lower numbers, but no close association with cutin formation has been identified. The possibility of multiple export mechanisms for cuticular components acting in parallel will be discussed, together with proposals for how cuticle precursors may traverse the polysaccharide cell wall before their assimilation into the cuticle macromolecular architecture.


2022 ◽  
Vol 81 ◽  
pp. 103122
Author(s):  
Hongmei Zhu ◽  
Yongbo Shao ◽  
Guoqiang Chi ◽  
Xudong Gao ◽  
Kangshuai Li

2021 ◽  
Author(s):  
Loes E. Wiersma ◽  
M. Cristina Avramut ◽  
Ellen Lievers ◽  
Ton J. Rabelink ◽  
Cathelijne W van den Berg

Abstract Background The generation of human induced pluripotent stem cells (hiPSCs) has opened a world of opportunities for stem cell-based therapies in regenerative medicine. Currently, several human kidney organoid protocols are available that generate organoids containing kidney structures. However, these kidney organoids are relatively small ranging up to 0.13 cm2 and therefore contain a small number of nephrons compared to an adult kidney, thus defying the exploration of future use for therapy. Method We have developed a scalable, easily accessible, and reproducible to increase the size of the organoid up to a nephron sheet of 2.5 cm2 up to a maximum of 12.6 cm2 containing a magnitude of nephrons. Results Confocal microscopy showed that the subunits of the nephrons remain evenly distributed throughout the entire sheet and that these tissue sheets can attain ~30,000-40,000 glomerular structures. Upon transplantation in immunodeficient mice, such nephron sheets became vascularized and matured. They also show reuptake of injected low-molecular mass dextran molecules in the tubular structures, indicative of glomerular filtration. Furthermore, we developed a protocol for the cryopreservation of intermediate mesoderm cells during the differentiation and demonstrate that these cells can be successfully thawed and recovered to create such tissue sheets. Conclusion The scalability of the procedures, and the ability to cryopreserve the cells during differentiation are important steps forward in the translation of these differentiation protocols to future clinical applications such as transplantable auxiliary kidney tissue.


2021 ◽  
Vol 9 ◽  
Author(s):  
Gui-Yuan Wu ◽  
Hong-Juan Zhu ◽  
Fang-Fang Pan ◽  
Xiao-Wei Sheng ◽  
Ming-Rui Zhang ◽  
...  

Transition metal-mediated templating and self-assembly have shown great potential to construct mechanically interlocked molecules. Herein, we describe the formation of the bimetallic [3]catenane and [4]catenane based on neutral organometallic scaffolds via the orthogonality of platinum-to-oxygen coordination-driven self-assembly and copper(I) template–directed strategy of a [2]pseudorotaxane. The structures of these bimetallic [3]catenane and [4]catenane were characterized by multinuclear NMR {1H and 31P} spectroscopy, electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS), and PM6 semiempirical molecular orbital theoretical calculations. In addition, single-crystal X-ray analyses of the [3]catenane revealed two asymmetric [2]pseudorotaxane units inside the metallacycle. It was discovered that tubular structures were formed through the stacking of individual [3]catenane molecules driven by the strong π–π interactions.


Micromachines ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1538
Author(s):  
Lothar Koch ◽  
Andrea Deiwick ◽  
Boris Chichkov

Bioprinting is seen as a promising technique for tissue engineering, with hopes of one day being able to produce whole organs. However, thick tissue requires a functional vascular network, which naturally contains vessels of various sizes, down to capillaries of ~10 µm in diameter, often spaced less than 200 µm apart. If such thick tissues are to be printed, the vasculature would likely need to be printed at the same time, including the capillaries. While there are many approaches in tissue engineering to produce larger vessels in a defined manner, the small capillaries usually arise only in random patterns by sprouting from the larger vessels or from randomly distributed endothelial cells. Here, we investigated whether the small capillaries could also be printed in predefined patterns. For this purpose, we used a laser-based bioprinting technique that allows for the combination of high resolution and high cell density. Our aim was to achieve the formation of closed tubular structures with lumina by laser-printed endothelial cells along the printed patterns on a surface and in bioprinted tissue. This study shows that such capillaries are directly printable; however, persistence of the printed tubular structures was achieved only in tissue with external stimulation by other cell types.


2021 ◽  
Vol 41 (4) ◽  
Author(s):  
A. E. López-Pérez ◽  
B. Rubio ◽  
D. Rey ◽  
M. Plaza-Morlote

AbstractSurficial sediments on the seafloor from passive continental margins can provide insight into recent Late Quaternary sedimentary dynamics acting over offshore sedimentary systems. This work focuses on the study of some particular ferruginous tubular structures resembling bioforms (FTB) located in the distal Galician Continental Margin (NW Iberian Margin) at water depths between ~ 1550 and ~ 2200 m. The characterisation of these structures made it possible to study in depth their formation environment and subsequent sedimentary evolution during the Late Pleistocene and Holocene. The FTB consist of goethite with a framboidal texture. They were interpreted as formed by an initial pyrite precipitation in reducing microenvironments conditioned by the activity of sediment-dwelling organisms during the early diagenesis. This is followed by the oxidation of pyrite by a combination of hydrothermal fluids and erosional processes, which triggers the formation of the framboidal oxyhydroxides. The data allowed obtaining a comprehensive understanding of the environmental context and the significance of these ferruginous tubules, as there are no previous studies in the scientific literature that describe these structures in a source-to-sink sedimentary system.


Author(s):  
Maja Remskar ◽  
Andreas K. Hüttel ◽  
Tatiana V. Shubina ◽  
Alan Seabaugh ◽  
Sara Fathipour ◽  
...  

2021 ◽  
Author(s):  
Mauro Pulin ◽  
Kilian E. Stockhausen ◽  
Olivia Andrea Masseck ◽  
Martin Kubitschke ◽  
Bjoern Busse ◽  
...  

Fluorescent proteins such as GFP are best excited by light that is polarized parallel to the dipole axis of the fluorophore. In most cases, fluorescent proteins are randomly oriented, resulting in unbiased images even when polarized light is used for excitation, e.g. in two-photon microcopy. Here we reveal a surprisingly strong polarization sensitivity in a class of GPCR-based neurotransmitter sensors where the fluorophore is anchored on both ends. In tubular structures such as dendrites, this effect led to a complete loss of membrane signal in dendrites running parallel to the polarization direction of the excitation beam. Our data reveal a major problem for two-photon measurements of neurotransmitter concentration that has not been recognized by the neuroscience community. To remedy the sensitivity to dendritic orientation, we designed an optical device that generates interleaved pulse trains of orthogonal polarization, removing the orientation bias from images. The passive device, which we inserted in the beam path of an existing two-photon microscope, also removed the strong direction bias in second harmonic generation (SHG) images. We conclude that for optical measurements of transmitter concentration with GPCR-based sensors, orthogonally polarized excitation is essential.


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