Статті в журналах: "Anisotropic regulator"

1

Abufanas, A. S., A. A. Lobaty, and Yu F. Yacina. "ANISOTROPIC REGULATOR OF DAMPING OF RANDOM VIBRATIONS OF THE MOBILE PLATFORM OF A BILAMENT VEHICLE APPARATUS." «System analysis and applied information science», no. 3 (November 2, 2017): 13–19. http://dx.doi.org/10.21122/2309-4923-2017-3-13-19.

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The problem of damping of random effects on a mobile platform with a system for monitoring the earth’s surface installed on an unmanned aerial vehicle is considered. As an external influence, we consider the random turbulence of the atmosphere, described with the aid of a shaping filter, to which white noise enters. Monitoring system with a mobile platform is considered as a control system, the criterion of optimality of which is proposed to use the criterion of quality of the stochastic norm of the system, which quantitatively characterizes the sensitivity of the output of the system to random input disturbances whose probabilistic distribution is not known accurately. This leads to a special variant of the stochastic norm-the anisotropic norm. A technique for constructing a robust phase control system using an anisotropic regulator is considered. The coefficients of the optimal regulator are obtained by mathematical modeling. As an example for evaluating the operability of the proposed algorithm, one of the control channels of the mobile platform, defined by a discrete mathematical model of the second order, is considered. Qualitative illustrations of the operability of the proposed algorithm and quantitative characteristics of the change in output signals are presented. The use of anisotropic regulators in damping systems of random effects is promising, since it allows to reduce the influence on the quality of the system operation of uncertainties caused by the differences between the chosen mathematical model and the real optimized system.

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2

Ishimoto, Takuya, Keita Kawahara, Aira Matsugaki, Jun Wang, Hiroshi Kamioka, and Takayoshi Nakano. "Analysis of Osteocyte Morphology in Terms of Sensation of In Vivo Stress Applied on Bone." Materials Science Forum 783-786 (May 2014): 1265–68. http://dx.doi.org/10.4028/www.scientific.net/msf.783-786.1265.

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Most bones are anisotropically loaded and seem to be adapted to the anisotropic stress or strain field by changing the anisotropy in their microstructure. Osteocyte (OCY) is believed to play an important role as a mechanosensor and regulator of modeling and/or remodeling orchestrating osteoblast and osteoclast activity to make bone suitable to resist the mechanical environment. In general, osteocytes sense magnitude of stress (strain) applied upon the bone and then work as a trigger to change bone mass to adjust bone’s mechanical function to the stress field. This structural optimization is an important aspect of the bone functional adaptation; another inevitable optimization might be achieved through the change in intrinsic material anisotropy including the preferential c-axis orientation of biological apatite (BAp) crystal. To achieve this adaptation through material anisotropy, osteocyte needs to be a mechanosensor which can detect anisotropic stress field. In the present study, osteocyte lacunae and canaliculi in the mid-diaphysis and the distal part of the rat femur were stained by a fluorescein dye for visualization and analysis. The mid-diaphysis shows greater degree of the preferential c-axis orientation of BAp crystal than the distal part in relation to the magnitude of uni-axial stress field. It was found that the osteocytes in long bone preferentially align along the bone long axis and the degree of alignment is greater in the mid-diaphysis than in the distal region, which seems to be effective for the sensation of the site-dependent specific stress field applied on the long bone.

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3

Greig, Joshua, and Natalia A. Bulgakova. "Interplay between actomyosin and E-cadherin dynamics regulates cell shape in the Drosophila embryonic epidermis." Journal of Cell Science 133, no. 15 (July 14, 2020): jcs242321. http://dx.doi.org/10.1242/jcs.242321.

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ABSTRACTPrecise regulation of cell shape is vital for building functional tissues. Here, we study the mechanisms that lead to the formation of highly elongated anisotropic epithelial cells in the Drosophila epidermis. We demonstrate that this cell shape is the result of two counteracting mechanisms at the cell surface that regulate the degree of elongation: actomyosin, which inhibits cell elongation downstream of RhoA (Rho1 in Drosophila) and intercellular adhesion, modulated via clathrin-mediated endocytosis of E-cadherin (encoded by shotgun in flies), which promotes cell elongation downstream of the GTPase Arf1 (Arf79F in Drosophila). We show that these two mechanisms do not act independently but are interconnected, with RhoA signalling reducing Arf1 recruitment to the plasma membrane. Additionally, cell adhesion itself regulates both mechanisms – p120-catenin, a regulator of intercellular adhesion, promotes the activity of both Arf1 and RhoA. Altogether, we uncover a complex network of interactions between cell–cell adhesion, the endocytic machinery and the actomyosin cortex, and demonstrate how this network regulates cell shape in an epithelial tissue in vivo.

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4

Weirich, Kimberly L., Shiladitya Banerjee, Kinjal Dasbiswas, Thomas A. Witten, Suriyanarayanan Vaikuntanathan, and Margaret L. Gardel. "Liquid behavior of cross-linked actin bundles." Proceedings of the National Academy of Sciences 114, no. 9 (February 15, 2017): 2131–36. http://dx.doi.org/10.1073/pnas.1616133114.

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The actin cytoskeleton is a critical regulator of cytoplasmic architecture and mechanics, essential in a myriad of physiological processes. Here we demonstrate a liquid phase of actin filaments in the presence of the physiological cross-linker, filamin. Filamin condenses short actin filaments into spindle-shaped droplets, or tactoids, with shape dynamics consistent with a continuum model of anisotropic liquids. We find that cross-linker density controls the droplet shape and deformation timescales, consistent with a variable interfacial tension and viscosity. Near the liquid–solid transition, cross-linked actin bundles show behaviors reminiscent of fluid threads, including capillary instabilities and contraction. These data reveal a liquid droplet phase of actin, demixed from the surrounding solution and dominated by interfacial tension. These results suggest a mechanism to control organization, morphology, and dynamics of the actin cytoskeleton.

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5

Chilton, Beverly S., and Aveline Hewetson. "Progesterone regulation of RUSH/SMARCA3/HLTF includes DNA looping." Biochemical Society Transactions 36, no. 4 (July 22, 2008): 632–36. http://dx.doi.org/10.1042/bst0360632.

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RUSH/SMARCA3 (SWI/SNF-related matrix-associated actin-dependent regulator of chromatin subfamily A, member 3) is capable of sequence-selective DNA binding and ATP-dependent DNA unwinding. In rabbit uterine epithelial cells, RUSH-1α (113 kDa) is the progesterone-dependent splice variant and RUSH-1β (95 kDa) is the oestrogen-dependent splice variant. Rabbit RUSH/SMARCA3 mRNA is primarily regulated at the proximal promoter (−162/+90) via a PRE (progesterone-response element) half-site/overlapping Y-box domain (−38/−26) and two Sp (specificity protein) 3 sites centred at −128 and −58. We investigated hormone regulation by exploring binding of transcription factors to a putative RUSH/SMARCA3 site (−616/−611) and the distal Sp3 (−131/−126) site. In response to progesterone, RUSH-1α binds the RUSH site and the Sp3 site becomes a functional binding site for Egr-1 (early growth-response gene product 1)/Sp (specificity protein)1/3/MAZ (Myc-associated zinc-finger protein)/MZF1 (myeloid zinc finger 1)/c-Rel. TransSignal TF–TF Interaction Arrays, supershift assays and ChIP (chromatin immunoprecipitation) analyses confirmed strong physical interactions between RUSH and Egr-1/c-Rel. Higher-order long-range interactions between RUSH and the Egr-1/c-Rel derivative of the anisotropic flexibility of the intervening DNA sequence were shown with 3C (chromosome conformation capture) assays. Transient transfection assays with mutant constructs showed the co-operative interaction between RUSH and Egr-1 mediates repression by c-Rel. Thus DNA-bound RUSH/SMARCA3 communicates with its own proximal promoter by looping the intervening DNA. Moreover, progesterone-dependent DNA looping is an adjunct to progesterone induction of the RUSH/SMARCA3 gene because the availability of RUSH isoforms and relevant binding partners is progesterone-regulated.

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6

Augustine, Sruthy Maria, Anoop V. Cherian, Divya P. Syamaladevi, and N. Subramonian. "Erianthus arundinaceusHSP70 (EaHSP70) Acts as a Key Regulator in the Formation of Anisotropic Interdigitation in Sugarcane (Saccharumspp. hybrid) in Response to Drought Stress." Plant and Cell Physiology 56, no. 12 (September 30, 2015): 2368–80. http://dx.doi.org/10.1093/pcp/pcv142.

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7

Haiza, Haroon, A. Azizan, Aizat Hazwan Mohidin, and D. S. C. Halin. "Green Synthesis of Silver Nanoparticles Using Local Honey." Nano Hybrids 4 (May 2013): 87–98. http://dx.doi.org/10.4028/www.scientific.net/nh.4.87.

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In this work, silver nanoparticles have been successfully prepared with a simple, cost-effective and reproducible aqueous room temperature green synthesis method. Honey was chosen as the eco-friendly reducing and stabilizing agent replacing most reported reducing agents such as hydrazine, sodium borohydride (NaBH4) and dimethyl formamide (DMF) which are highly reactive chemicals but also pose a biological risk to the society and environment. The size and shape of silver nanoparticles were modulated by varying the honey concentration and pH of the aqueous solution that contain silver nitrate as the silver precursor, sodium hydroxide as the pH regulator and ethylene glycol as the solvent. The silver nanoparticles obtained are characterized by field-emission scanning electron microscope (FESEM), ultraviolet-visible spectra (UV-Vis) and Fourier transform infrared spectroscopy (FTIR). From SEM analysis, it was found that by increasing the concentration of honey, the size of silver nanoparticles produced decreased, from the range of 18.98 nm - 26.05 nm for 10 g of honey to 15.63 nm - 17.86 nm for 40 g of honey. Similarly, the particle size decreased as the pH of the aqueous solution increased. UV-Vis spectra revealed large anisotropic and polydispersed Ag nanoparticle were produced.

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8

Nam, Dayeon, Yuki Matsumoto, Takeshi Uchida, Mark R. O'Brian, and Koichiro Ishimori. "Mechanistic insights into heme-mediated transcriptional regulation via a bacterial manganese-binding iron regulator, iron response regulator (Irr)." Journal of Biological Chemistry 295, no. 32 (June 17, 2020): 11316–25. http://dx.doi.org/10.1074/jbc.ra119.011855.

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The transcription factor iron response regulator (Irr) is a key regulator of iron homeostasis in the nitrogen-fixating bacterium Bradyrhizobium japonicum. Irr acts by binding to target genes, including the iron control element (ICE), and is degraded in response to heme binding. Here, we examined this binding activity using fluorescence anisotropy with a 6-carboxyfluorescein-labeled ICE-like oligomer (FAM-ICE). In the presence of Mn2+, Irr addition increased the fluorescence anisotropy, corresponding to formation of the Irr–ICE complex. The addition of EDTA to the Irr–ICE complex reduced fluorescence anisotropy, but fluorescence was recovered after Mn2+ addition, indicating that Mn2+ binding is a prerequisite for complex formation. Binding activity toward ICE was lost upon introduction of substitutions in a His-cluster region of Irr, revealing that Mn2+ binds to this region. We observed that the His-cluster region is also the heme binding site; results from fluorescence anisotropy and electrophoretic mobility shift analyses disclosed that the addition of a half-equivalent of heme dissociates Irr from ICE, likely because of Mn2+ release due to heme binding. We hypothesized that heme binding to another heme binding site, Cys-29, would also inhibit the formation of the Irr–ICE complex because it is proximal to the ICE binding site, which was supported by the loss of ICE binding activity in a Cys-29–mutated Irr. These results indicate that Irr requires Mn2+ binding to form the Irr–ICE complex and that the addition of heme dissociates Irr from ICE by replacing Mn2+ with heme or by heme binding to Cys-29.

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9

Matsugaki, Aira, Ryosuke Ozasa, Yoshihiro Isobe, Taro Saku, and Takayoshi Nakano. "Oriented Collagen Scaffolds for Anisotropic Bone Tissue Construction In Vitro." Materials Science Forum 783-786 (May 2014): 1303–6. http://dx.doi.org/10.4028/www.scientific.net/msf.783-786.1303.

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Constructing biomimetic tissue architecture in vitro holds the key to the realization of tissue engineering. To control the anisotropic microstructure of bone tissue which governs the mechanical properties of bone, especially, is imperative for the establishment of ideal bone regeneration process. In this study, highly aligned collagen scaffolds were fabricated to control osteoblast alignment. Collagen fibrillogenesis were regulated by an extrusion process, resulting in formation of biomimetic, hierarchically-aligned bony microstructure. Osteoblasts adhered to the fabricated scaffolds showed aligned morphology along the collagen orientation. In the present method, the degree of scaffold orientation is regulatable, which suggests that the designing of the appropriate scaffolds depending on the tissue anisotropy is possible. Interestingly, the bone matrix produced by the aligned osteoblasts exhibited anisotropic microstructure along the cell alignment. Our findings imply that controlling the osteoblast alignment by oriented collagen scaffolds could be an initiator to establish the anisotropic bone structural development or regeneration.

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10

Deng, Chao, Jue Hou, Xing Zhang, R. Hugh Gong, and Xiangyu Jin. "Controllable anisotropic properties of wet-laid hydroentangled nonwovens." March 2019 18, no. 3 (April 1, 2019): 173–80. http://dx.doi.org/10.32964/tj18.3.173.

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For nonwovens, fiber orientation distribution is an important structural characteristic that directly influences the anisotropic properties of the materials. Different Vslurry/Vbelt ratios were adopted to fabricate nonwovens during the wet-laid process. The results indicated that fiber orientation distribution of nonwovens can be regulated by adopting different Vslurry/Vbelt ratios owing to the web-forming principle of wet-laid techniques. Mechanical tests showed that both wet and dry tensile strength of nonwovens in different angle directions present anisotropy under different Vslurry/Vbelt ratio parameters. A liquid spreading distribution experiment proved that liquid spreading length and area of nonwovens could be manipulated using different Vslurry/Vbelt ratios in the fabrication process. Therefore, specific anisotropic properties of wet-laid hydroentangled nonwovens can be realized by controlling the process parameters for particular end-use applications.

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11

Simões, Sérgio, Youjin Oh, Michael F. Z. Wang, Rodrigo Fernandez-Gonzalez, and Ulrich Tepass. "Myosin II promotes the anisotropic loss of the apical domain during Drosophila neuroblast ingression." Journal of Cell Biology 216, no. 5 (March 31, 2017): 1387–404. http://dx.doi.org/10.1083/jcb.201608038.

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Epithelial–mesenchymal transitions play key roles in development and cancer and entail the loss of epithelial polarity and cell adhesion. In this study, we use quantitative live imaging of ingressing neuroblasts (NBs) in Drosophila melanogaster embryos to assess apical domain loss and junctional disassembly. Ingression is independent of the Snail family of transcriptional repressors and down-regulation of Drosophila E-cadherin (DEcad) transcription. Instead, the posttranscriptionally regulated decrease in DEcad coincides with the reduction of cell contact length and depends on tension anisotropy between NBs and their neighbors. A major driver of apical constriction and junctional disassembly are periodic pulses of junctional and medial myosin II that result in progressively stronger cortical contractions during ingression. Effective contractions require the molecular coupling between myosin and junctions and apical relaxation of neighboring cells. Moreover, planar polarization of myosin leads to the loss of anterior–posterior junctions before the loss of dorsal–ventral junctions. We conclude that planar-polarized dynamic actomyosin networks drive apical constriction and the anisotropic loss of cell contacts during NB ingression.

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12

Zhang, Zheng-Zheng, You-Rong Chen, Shao-Jie Wang, Feng Zhao, Xiao-Gang Wang, Fei Yang, Jin-Jun Shi, et al. "Orchestrated biomechanical, structural, and biochemical stimuli for engineering anisotropic meniscus." Science Translational Medicine 11, no. 487 (April 10, 2019): eaao0750. http://dx.doi.org/10.1126/scitranslmed.aao0750.

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Reconstruction of the anisotropic structure and proper function of the knee meniscus remains an important challenge to overcome, because the complexity of the zonal tissue organization in the meniscus has important roles in load bearing and shock absorption. Current tissue engineering solutions for meniscus reconstruction have failed to achieve and maintain the proper function in vivo because they have generated homogeneous tissues, leading to long-term joint degeneration. To address this challenge, we applied biomechanical and biochemical stimuli to mesenchymal stem cells seeded into a biomimetic scaffold to induce spatial regulation of fibrochondrocyte differentiation, resulting in physiological anisotropy in the engineered meniscus. Using a customized dynamic tension-compression loading system in conjunction with two growth factors, we induced zonal, layer-specific expression of type I and type II collagens with similar structure and function to those present in the native meniscus tissue. Engineered meniscus demonstrated long-term chondroprotection of the knee joint in a rabbit model. This study simultaneously applied biomechanical, biochemical, and structural cues to achieve anisotropic reconstruction of the meniscus, demonstrating the utility of anisotropic engineered meniscus for long-term knee chondroprotection in vivo.

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13

Anand, Ruchi, and Hussain Bhukya. "Structural Insights into Mechanism of Antibiotic Regulation in Streptomyces." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C700. http://dx.doi.org/10.1107/s2053273314092997.

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Streptomyces species are well-known for their wide variety of biologically active secondary metabolites and contribute to two-third of naturally occurring antibiotics. Production of antibiotics and resistance pathways in these species are dictated by interplay of transcriptional regulatory proteins that trigger downstream responses to either small diffusible molecules (autoinducers) or by binding to the antibiotic intermediates. These regulators have a ligand binding site and a DNA binding site and they carry out their transcription regulation via conformational changes induced upon ligand or DNA binding. To decipher the structural mechanism of action here we present the crystal structure of CprB in complex with its consensus DNA element to a resolution of 3.2 Å. The structure revealed that CprB belongs to the tetracycline family of antibiotic resistance efflux pumps regulators. CprB binds to the DNA as a tetramer via the helix-turn-helix (HTH) motif with the mode of DNA binding is most analogous to that observed for the broad spectrum multidrug resistance regulator QacR from Staphylococcus aureus. The binding of the DNA induces the restructuring of the CprB dimeric interface, thereby inducing a pendulum like motion of the HTH motif that inserts into the major grove of the DNA. A genome wide search for the cognate DNA element revealed that CprB serves as an autoregulatory protein and binds to its own promoter sequence. Our studies suggest that CprB is a part of a network of proteins that regulate the antibiotic production and resistance pathways in Streptomyces. Fluorescence anisotropy lifetime studies performed with both consensus and CprB promoter helped in concluding that both the sequence have an analogous mode of binding with the CprB DNA exhibiting a stronger binding profile as supported by ITC studies. A sequential binding mode, similar to a clamp and click model of binding was proposed.

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14

Yang, Yanqiu, Binqinq Chen, Xie Dang, Lilan Zhu, Jinqiu Rao, Huibo Ren, Chentao Lin, Yuan Qin, and Deshu Lin. "Arabidopsis IPGA1 is a microtubule-associated protein essential for cell expansion during petal morphogenesis." Journal of Experimental Botany 70, no. 19 (June 13, 2019): 5231–43. http://dx.doi.org/10.1093/jxb/erz284.

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Abstract Unlike animal cells, plant cells do not possess centrosomes that serve as microtubule organizing centers; how microtubule arrays are organized throughout plant morphogenesis remains poorly understood. We report here that Arabidopsis INCREASED PETAL GROWTH ANISOTROPY 1 (IPGA1), a previously uncharacterized microtubule-associated protein, regulates petal growth and shape by affecting cortical microtubule organization. Through a genetic screen, we showed that IPGA1 loss-of-function mutants displayed a phenotype of longer and narrower petals, as well as increased anisotropic cell expansion of the petal epidermis in the late phases of flower development. Map-based cloning studies revealed that IPGA1 encodes a previously uncharacterized protein that colocalizes with and directly binds to microtubules. IPGA1 plays a negative role in the organization of cortical microtubules into parallel arrays oriented perpendicular to the axis of cell elongation, with the ipga1-1 mutant displaying increased microtubule ordering in petal abaxial epidermal cells. The IPGA1 family is conserved among land plants and its homologs may have evolved to regulate microtubule organization. Taken together, our findings identify IPGA1 as a novel microtubule-associated protein and provide significant insights into IPGA1-mediated microtubule organization and petal growth anisotropy.

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15

Liu, Guang, Liwen Zhang, Yang Gan, Yan Wang, Dengke Chen, Yuguo Dai, Lin Feng, Pengfei Zhang, and Huawei Chen. "Liquid transport with direction guidance and speed enhancement from gradient and magnetized micro-cilia surface." Applied Physics Letters 120, no. 19 (May 9, 2022): 191603. http://dx.doi.org/10.1063/5.0089149.

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Liquid transport regulation has attracted wide attention recently due to its potential applications in micro-fluidic devices, heat management, and mechanical engineering. Various liquid regulation strategies for direction guiding and speed enhancing have been developed with inspirations from nature, such as desert beetles and Nepenthes alata peristome with either gradient wettability or anisotropic structures, whereas their combined strategies for enhanced liquid regulations have barely been discussed due to the unclear coupling mechanisms. Herein, inspired by liquid transporting structure on Ligia exotica's leg, a smart flexible surface with gradient distributed and magnetized micro-cilia array is proposed to realize liquid spreading regulations in speed and direction. Different gradients and magnetic fields have been compared for liquid regulating performances, where the anisotropy ratio of liquid spreading could be enhanced from 0 on uniform surface to ∼0.3 on gradients surface, to even ∼0.6 by coupling magnetic field. The underlying liquid regulating mechanism has been established based on the mutual effects of liquid pinning and capillarity at different cilium inclined angles, cilium gap distance, and surface wettability. Finally, several liquid regulation applications are explored and offer potentials for fields of medicine and heat management.

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16

Suzuki, Aline Yasko Marinho, Cibele Souza Bedetti, and Rosy Mary dos Santos Isaias. "Detection and distribution of cell growth regulators and cellulose microfibrils during the development of Lopesia sp. galls on Lonchocarpus cultratus (Fabaceae)." Botany 93, no. 7 (July 2015): 435–44. http://dx.doi.org/10.1139/cjb-2015-0012.

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Gall-inducing insects cause their plant hosts’ cells to redifferentiate, divide, and elongate, which are processes mediated by cell growth regulators. In this study, the histochemical detection of these regulators, and of cellulose microfibrils were performed in a gall induced by Lopesia sp. (Cecidomyiidae) on Lonchocarpus cultratus (Vell.) A.M.G.Azevedo & H.C.Lima. The co-occurrence of reactive oxygen species, (poly)phenols, flavonoids, and indole-3-acetic acid are age-independent and are detected at the sites of cell hypertrophy. Nevertheless, the intensity of the reactions may vary from young to mature galls. First, changes in the axis of cell elongation are observed from the non-galled leaflets to the young galls, in the cortical parenchyma and in the nutritive tissue. During maturation, the elongation axis of the nutritive cells changes again. In young galls, sites of hyperplasia and hypertrophy co-occur, and in mature galls, the orientation of cellulose microfibrils determines the predominant anisotropic pattern of cell expansion. The detection of (poly)phenols and indole-3-acetic acid, reactive oxygen species, and flavonoids coincide with the sites of cell elongation and division. These results denote a chemical balance between the regulation of growth and the avoidance of cell death at gall sites. The rearrangement of cellulose microfibrils coordinates the anisotropic expansion, which determines the development of the tissue projections both to adaxial and abaxial leaflet lamina, typical to this gall morphotype.

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17

Huang, Ruoyu, Raymond W. Ogden, and Raimondo Penta. "Mathematical Modelling of Residual-Stress Based Volumetric Growth in Soft Matter." Journal of Elasticity 145, no. 1-2 (May 20, 2021): 223–41. http://dx.doi.org/10.1007/s10659-021-09834-8.

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AbstractGrowth in nature is associated with the development of residual stresses and is in general heterogeneous and anisotropic at all scales. Residual stress in an unloaded configuration of a growing material provides direct evidence of the mechanical regulation of heterogeneity and anisotropy of growth. The present study explores a model of stress-mediated growth based on the unloaded configuration that considers either the residual stress or the deformation gradient relative to the unloaded configuration as a growth variable. This makes it possible to analyze stress-mediated growth without the need to invoke the existence of a fictitious stress-free grown configuration. Furthermore, applications based on the proposed theoretical framework relate directly to practical experimental scenarios involving the “opening-angle” in arteries as a measure of residual stress. An initial illustration of the theory is then provided by considering the growth of a spherically symmetric thick-walled shell subjected to the incompressibility constraint.

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18

Leng, Chuntao, Qixin Cao, and Yanwen Huang. "A Motion Planning Method for Omnidirectional Mobile Robot Based on the Anisotropic Characteristics." International Journal of Advanced Robotic Systems 5, no. 4 (November 1, 2008): 45. http://dx.doi.org/10.5772/6228.

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A more suitable motion planning method for an omni-directional mobile robot (OMR), an improved APF method (iAPF), is proposed in this paper by introducing the revolving factor into the artificial potential field (APF). Accordingly, the motion direction derived from traditional artificial potential field (tAPF) is regulated. The maximum velocity, maximum acceleration and energy consumption of the OMR moving in different directions are analyzed, based on the kinematic and dynamic constraints of an OMR, and the anisotropy of OMR is presented in this paper. Then the novel concept of an Anisotropic-Function is proposed to indicate the quality of motion in different directions, which can make a very favorable trade-off between time-optimality, stability and efficacy-optimality. In order to obtain the optimal motion, the path that the robot can take in order to avoid the obstacle safely and reach the goal in a shorter path is deduced. Finally, simulations and experiments are carried out to demonstrate that the motion resulting from the iAPF is high-speed, highly stable and highly efficient when compared to the tAPF.

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19

Makhutov, Nikolai A., Ivan V. Makarenko, and Leonid V. Makarenko. "Kinetics of the multidirectionality of elastic-plastic fracture with allowance for anisotropy of the material properties." Industrial laboratory. Diagnostics of materials 86, no. 1 (January 30, 2020): 44–50. http://dx.doi.org/10.26896/1028-6861-2020-86-1-44-50.

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Survivability, service life and operational safety of the engineering structures are determined by their damage rate which is mainly regulated by the presence and development of the crack-like defects in the material. Kinetic dependences describing the development of multidirectional semi-elliptic surface cracks with allowance for the anisotropy of the material properties are proposed proceeding from experimental data and numerical solutions. The obtained results are required in studying kinematic problems in nonlinear mechanics of a continuous anisotropic medium. Refining parametric equations for elastoplastic deformation anisotropy are proposed. Functional dependences of the parameters of the kinetic diagrams of low-cycle fracture on the mechanical properties of the material are presented for a wide class of welded joints of austenite stainless cyclically stable steels (12Kh18N10T). The processes of developing inclined semi-elliptic surface cracks in the continuums of welded joints under non-linear boundary loading conditions are studied. We have carried out combined computational, experimental and numerical studies of the stress-strain state in the vicinity of the contour of stationary and growing surface semi-elliptic cracks randomly oriented in space under elastoplastic nominal cyclic loading taking into account the anisotropy of the material properties. The functional distribution of the inhomogeneity parameter of the mechanical properties of the material, which affects accumulation of the local plastic strains and direction of developing the elastoplastic fracture is obtained and presented in the form of the kinetic equation of nonlinear fracture mechanics. Comparison of the experimental results and numerical calculations of the stress-strain state along the contour of the cracks under study in nonlinear boundary loading conditions revealed a good agreement between the intensities of relative elastoplastic deformations at their surface points with allowance for the deformation anisotropy. Calculations of the elastoplastic fracture resistance of the critical elements of the equipment with allowance for considered factors of nonlinear fracture mechanics and heterogeneity of the properties can improve the accuracy of evaluation of their strength, service life and survivability.

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20

Liu, Yang, Xiaohan Song, Yanmei Yang, Yong-Qiang Li, Mingwen Zhao, Yuguang Mu, and Weifeng Li. "Anisotropic protein diffusion on nanosurface." Nanoscale 12, no. 8 (2020): 5209–16. http://dx.doi.org/10.1039/c9nr08555f.

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The migration of protein is regulated by the puckered surface of α-PC, resulting in quick and highly directional diffusion. In combination with the bio-compatibility, α-PC is expected to be a novel functional drug delivery agent in biomedical research.

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21

Käpylä, M. J., F. A. Gent, M. S. Väisälä, and G. R. Sarson. "The supernova-regulated ISM." Astronomy & Astrophysics 611 (March 2018): A15. http://dx.doi.org/10.1051/0004-6361/201731228.

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Context.The forcing of interstellar turbulence, driven mainly by supernova (SN) explosions, is irrotational in nature, but the development of significant amounts of vorticity and helicity, accompanied by large-scale dynamo action, has been reported.Aim.Several earlier investigations examined vorticity production in simpler systems; here all the relevant processes can be considered simultaneously. We also investigate the mechanisms for the generation of net helicity and large-scale flow in the system.Methods.We use a three-dimensional, stratified, rotating and shearing local simulation domain of the size 1 × 1 × 2 kpc3, forced with SN explosions occurring at a rate typical of the solar neighbourhood in the Milky Way. In addition to the nominal simulation run with realistic Milky Way parameters, we vary the rotation and shear rates, but keep the absolute value of their ratio fixed. Reversing the sign of shear vs. rotation allows us to separate the rotation- and shear-generated contributions.Results.As in earlier studies, we find the generation of significant amounts of vorticity, the rotational flow comprising on average 65% of the total flow. The vorticity production can be related to the baroclinicity of the flow, especially in the regions of hot, dilute clustered supernova bubbles. In these regions, the vortex stretching acts as a sink of vorticity. In denser, compressed regions, the vortex stretching amplifies vorticity, but remains sub-dominant to baroclinicity. The net helicities produced by rotation and shear are of opposite signs for physically motivated rotation laws, with the solar neighbourhood parameters resulting in the near cancellation of the total net helicity. We also find the excitation of oscillatory mean flows, the strength and oscillation period of which depend on the Coriolis and shear parameters; we interpret these as signatures of the anisotropic-kinetic-α(AKA) effect. We use the method of moments to fit for the turbulent transport coefficients, and findαAKAvalues of the order 3–5 km s−1.Conclusions.Even in a weakly rotationally and shear-influenced system, small-scale anisotropies can lead to significant effects at large scales. Here we report on two consequences of such effects, namely on the generation of net helicity and on the emergence of large-scale flows by the AKA effect, the latter detected for the first time in a direct numerical simulation of a realistic astrophysical system.

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Crowell, Elizabeth Faris, Martine Gonneau, Samantha Vernhettes, and Herman Höfte. "Regulation of anisotropic cell expansion in higher plants." Comptes Rendus Biologies 333, no. 4 (April 2010): 320–24. http://dx.doi.org/10.1016/j.crvi.2010.01.007.

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Ghosh, Debasish Kumar, Debdeep Dasgupta, and Abhishek Guha. "Models, Regulations, and Functions of Microtubule Severing by Katanin." ISRN Molecular Biology 2012 (September 27, 2012): 1–14. http://dx.doi.org/10.5402/2012/596289.

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Regulation of microtubule dynamics depends on stochastic balance between polymerization and severing process which lead to differential spatiotemporal abundance and distribution of microtubules during cell development, differentiation, and morphogenesis. Microtubule severing by a conserved AAA family protein Katanin has emerged as an important microtubule architecture modulating process in cellular functions like division, migration, shaping and so on. Regulated by several factors, Katanin manifests connective crosstalks in network motifs in regulation of anisotropic severing pattern of microtubule protofilaments in cell type and stage dependent way. Mechanisms of structural disintegration of microtubules by Katanin involve heterogeneous mechanochemical processes and sensitivity of microtubules to Katanin plays significant roles in mitosis/meiosis, neurogenesis, cilia/flagella formation, cell wall development and so on. Deregulated and uncoordinated expression of Katanin has been shown to have implications in pathophysiological conditions. In this paper, we highlight mechanistic models and regulations of microtubule severing by Katanin in context of structure and various functions of Katanin in different organisms.

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24

Shikinaka, Kazuhiro, Saori Mori, Kiyotaka Shigehara, and Hiroyasu Masunaga. "Helical alignment inversion of microtubules in accordance with a structural change in their lattice." Soft Matter 11, no. 19 (2015): 3869–74. http://dx.doi.org/10.1039/c5sm00488h.

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Finely-regulated giant helical alignments of microtubules with centimeter order according to their lattice structure form over a temperature gradient during anisotropic spiral propagation via tubulin dimer addition in a capillary cell.

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25

Wei, Zichen, Yang Yang, Chenyang Wang, Zhili Li, Lixian Zheng, and Jun Luo. "Enhanced room-temperature thermoelectric performance of p-type BiSbTe by reducing carrier concentration." RSC Advances 9, no. 4 (2019): 2252–57. http://dx.doi.org/10.1039/c8ra09771b.

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Ti substitution leads to enhanced thermoelectric performance of p-type Bi_0.5Sb_1.5Te₃ due to carrier concentration regulation, alloy effect and anisotropic microstructure.

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26

Jun, Indong, Hyung-Seop Han, Jae Won Lee, Kyungwoo Lee, Yu-Chan Kim, Myoung-Ryul Ok, Hyun-Kwang Seok, et al. "On/off switchable physical stimuli regulate the future direction of adherent cellular fate." Journal of Materials Chemistry B 9, no. 27 (2021): 5560–71. http://dx.doi.org/10.1039/d1tb00908g.

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A simple method to regulate cell function with anisotropic shape using enzymatically degradable alginate hydrogels offers physical stimuli for reversible cell patterning that allows regulation of the future direction of adherent cellular behaviors.

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27

Huang, Xiao, Yu Hai, and Wei-Hua Xie. "Anisotropic cell growth-regulated surface micropatterns in flower petals." Theoretical and Applied Mechanics Letters 7, no. 3 (May 2017): 169–74. http://dx.doi.org/10.1016/j.taml.2017.03.004.

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28

Lee, Yin-Hui, and Min-Fu Hsieh. "Swiveling Magnetization for Anisotropic Magnets for Variable Flux Spoke-Type Permanent Magnet Motor Applied to Electric Vehicles." Energies 15, no. 10 (May 23, 2022): 3825. http://dx.doi.org/10.3390/en15103825.

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This paper investigates the application of anisotropic low-coercive force (LCF) magnets to a novel variable-flux spoke-type permanent magnet synchronous motor (VFS-PMSM) for electrical vehicles with a wide speed range. In the VFS-PMSM, flux is regulated by swiveling the magnetization of the anisotropic LCF magnets instead of directly magnetizing or demagnetizing them. The previously proposed VFS-PMSM uses only isotropic LCF magnets for easily swiveling the magnetic pole direction, resulting in lower torque density. The challenge thus lies in the feasibility to swivel the magnetic pole direction of the anisotropic LCF magnet, and the impact of the different magnetization strengths of the anisotropic magnets on the motor performance. This paper first studies the feasibility to swivel the magnetization direction of anisotropic LCF magnets through experiments. It is confirmed that the magnetization direction can be successfully swiveled by 90 degrees with a reduced external magnetizing field. Then, two VFS-PMSM topologies and various rotor configurations are compared in terms of key performance indices to determine critical sizing factors for performance enhancement. Finite element analysis is used for simulations. In comparison with the VFS-PMSM equipped with isotropic LCF magnets, the maximum torque of the proposed topology can be improved for the same flux adjustment ability. Alternatively, the flux adjustment ability can also be enhanced by 37.43% for the same maximum torque.

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29

Li, Guicai, Tiantian Zheng, Linliang Wu, Qi Han, Yifeng Lei, Longjian Xue, Luzhong Zhang, Xiaosong Gu, and Yumin Yang. "Bionic microenvironment-inspired synergistic effect of anisotropic micro-nanocomposite topology and biology cues on peripheral nerve regeneration." Science Advances 7, no. 28 (July 2021): eabi5812. http://dx.doi.org/10.1126/sciadv.abi5812.

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Anisotropic topographies and biological cues can simulate the regenerative microenvironment of nerve from physical and biological aspects, which show promising application in nerve regeneration. However, their synergetic influence on injured peripheral nerve is rarely reported. In the present study, we constructed a bionic microenvironment-inspired scaffold integrated with both anisotropic micro-nanocomposite topographies and IKVAV peptide. The results showed that both the topographies and peptide displayed good stability. The scaffolds could effectively induce the orientation growth of Schwann cells and up-regulate the genes and proteins relevant to myelination. Last, three signal pathways including the Wnt/β-catenin pathway, the extracellular signal–regulated kinase/mitogen-activated protein pathway, and the transforming growth factor–β pathway were put forward, revealing the main path of synergistic effects of anisotropic micro-nanocomposite topographies and biological cues on neuroregeneration. The present study may supply an important strategy for developing functional of artificial nerve implants.

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Wang, Lingling, Cheng Zeng, Hong Xu, Panchao Yin, Dongcheng Chen, Jian Deng, Mu Li, Nan Zheng, Cheng Gu, and Yuguang Ma. "A highly soluble, crystalline covalent organic framework compatible with device implementation." Chemical Science 10, no. 4 (2019): 1023–28. http://dx.doi.org/10.1039/c8sc04255a.

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We report a soluble yet crystalline covalent organic framework (COF) by regulation of inter-layer interactions, which endows the COF with remarkable solubility and processability of thin films for optoelectronic devices that exhibit high yet anisotropic conductivities and outperform all the other COF-based semiconductors.

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31

Zhou, Shuai, Kechun Guo, Danil Bukhvalov, Wenzhuo Zhu, Jian Wang, Wen Sun, and Ming He. "H-bond/ionic coordination switching for fabrication of highly oriented cellulose hydrogels." Journal of Materials Chemistry A 9, no. 9 (2021): 5533–41. http://dx.doi.org/10.1039/d0ta10863d.

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The H₂O/Ca²⁺ exchange led to a facile switch between dominant H-bond and ionic coordination and achieved a continuous regulation for higher orientation. This unique strategy can be used for programmable design of various anisotropic hydrogels.

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32

Barrio, Lara, and Marco Milán. "Regulation of Anisotropic Tissue Growth by Two Orthogonal Signaling Centers." Developmental Cell 52, no. 5 (March 2020): 659–72. http://dx.doi.org/10.1016/j.devcel.2020.01.017.

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Rajput, Shailendra, Efim Lockshin, Aryeh Schochet, and Moshe Averbukh. "Reactance Regulation Using Coils with Perpendicular Magnetic Field in the Tubular Core design." Applied Sciences 10, no. 21 (October 29, 2020): 7645. http://dx.doi.org/10.3390/app10217645.

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This article presents an efficient method for prosumer connection to the distribution line. The prosumers can be connected to the distribution line using specially designed controllable reactive impedance. The reactive impedance is controlled using specially designed coils and magnetic core. The internal coil is wound in the toroidal direction (across the z-axis) and creates a toroidal shape. A thin ferromagnetic strip is coiled on this toroidal shape in the poloidal direction to form the ferromagnetic core. Then, an external coil is wound on this ferromagnetic core in the poloidal direction. The internal coil is controlled by the inductive impedance of the external coil, which is related to the anisotropic properties of ferromagnetic strips. The internal coil is connected between the power supply line and a prosumer. This arrangement confirms the magnetic independence of coils and the symmetry of the current in the internal coil. The magnetic coupling between both coils is very low (~0.015–0.017) and appropriate for engineering applications. It is approved that the impedance of the internal coil is changed due to the anisotropic magnetic properties of the core material.

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34

Espinoza, C. M., P. S. Moya, M. Stepanova, J. A. Valdivia, and R. E. Navarro. "Spontaneous Magnetic Fluctuations and Collisionless Regulation of Turbulence in the Earth’s Magnetotail." Astrophysical Journal 924, no. 1 (January 1, 2022): 8. http://dx.doi.org/10.3847/1538-4357/ac33a2.

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Abstract Among the fundamental and most challenging problems of laboratory, space, and astrophysical plasma physics is to understand the relaxation processes of nearly collisionless plasmas toward quasi-stationary states and the resultant states of electromagnetic plasma turbulence. Recently, it has been argued that solar wind plasma β and temperature anisotropy observations may be regulated by kinetic instabilities such as the ion cyclotron, mirror, electron cyclotron, and firehose instabilities; and it has been argued that magnetic fluctuation observations are consistent with the predictions of the fluctuation–dissipation theorem, even far below the kinetic instability thresholds. Here, using in situ magnetic field and plasma measurements by the THEMIS satellite mission, we show that such regulation seems to occur also in the Earth’s magnetotail plasma sheet at the ion and electron scales. Regardless of the clear differences between the solar wind and the magnetotail environments, our results indicate that spontaneous fluctuations and their collisionless regulation are fundamental features of space and astrophysical plasmas, thereby suggesting the processes is universal.

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35

Khabiuk, Andrii, and Oleh Danalakiy. "Research of operation of anisotropic optical thermoelement with lateral temperature regulation." Technology audit and production reserves 3, no. 1(35) (May 30, 2017): 49–53. http://dx.doi.org/10.15587/2312-8372.2017.105655.

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36

Zhang, Yun, Yongzhi Qiu, Aaron T. Blanchard, Yuan Chang, Josh M. Brockman, Victor Pui-Yan Ma, Wilbur A. Lam, and Khalid Salaita. "Platelet integrins exhibit anisotropic mechanosensing and harness piconewton forces to mediate platelet aggregation." Proceedings of the National Academy of Sciences 115, no. 2 (December 21, 2017): 325–30. http://dx.doi.org/10.1073/pnas.1710828115.

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Platelet aggregation at the site of vascular injury is essential in clotting. During this process, platelets are bridged by soluble fibrinogen that binds surface integrin receptors. One mystery in the mechanism of platelet aggregation pertains to how resting platelets ignore soluble fibrinogen, the third most abundant protein in the bloodstream, and yet avidly bind immobile fibrinogen on the surface of other platelets at the primary injury site. We speculate that platelet integrins are mechanosensors that test their ligands across the platelet–platelet synapse. To investigate this model, we interrogate human platelets using approaches that include the supported lipid bilayer platform as well as DNA tension sensor technologies. Experiments suggest that platelet integrins require lateral forces to mediate platelet–platelet interactions. Mechanically labile ligands dampen platelet activation, and the onset of piconewton integrin tension coincides with calcium flux. Activated platelets display immobilized fibrinogen on their surface, thus mediating further recruitment of resting platelets. The distribution of integrin tension was shown to be spatially regulated through two myosin-signaling pathways, myosin light chain kinase and Rho-associated kinase. Finally, we discovered that the termination of integrin tension is coupled with the exposure of phosphatidylserine. Our work reveals the highest spatial and temporal resolution maps of platelet integrin mechanics and its role in platelet aggregation, suggesting that platelets are physical substrates for one another that establish mechanical feedback loops of activation. The results are reminiscent of mechanical regulation of the T-cell receptor, E-cadherin, and Notch pathways, suggesting a common feature for signaling at cell junctions.

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37

Zhou, Xiaohu, Tianzhen Li, Jiahui Wang, Fan Chen, Dan Zhou, Qi Liu, Liyun Zhang, Jiayan Shen, and Xuechang Zhou. "Shape morphing of anisotropy-encoded tough hydrogels enabled by asymmetrically-induced swelling and site-specific mechanical strengthening." Journal of Materials Chemistry B 6, no. 29 (2018): 4731–37. http://dx.doi.org/10.1039/c8tb01372a.

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38

Webb, Nicole M. "The Functional and Allometric Implications of Hipbone Trabecular Microarchitecture in a Sample of Eutherian and Metatherian Mammals." Evolutionary Biology 48, no. 3 (June 1, 2021): 346–65. http://dx.doi.org/10.1007/s11692-021-09543-z.

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AbstractThe pelvis plays an active role in weight bearing and countering the ground reaction forces incurred by the hindlimbs thus making it a critical component of the locomotor skeleton. Accordingly, this anatomical region is theoretically ideal for inferring locomotor behavior from both external skeletal morphology and trabecular microarchitecture, with the latter possibly offering nuanced insights into the mechanical loading environment given its increased plasticity and higher turnover rate. However, trabecular microarchitecture is also known to be influenced by a variety of factors including body size, sex, age, genetic regulation, diet and activity level, that collectively hinder the ability to generate consistent functional inferences. In this study, a comparative sample of mammals (42 species spanning four orders) of varying sizes, yet comparable locomotor repertoires, were evaluated to determine the effects of body size, phylogeny and locomotion on hipbone trabecular microarchitecture. This study found a weak functional signal detected in differences in bone volume fraction and the degree of anisotropy across certain pre-assigned locomotor categories, while confirming previously recognized allometric scaling trends reported for other mammalian samples based on the femur. Within primates, a more anisotropic pattern was observed for quadrupedal species attributed to their repetitive loading regimes and stereotypical limb excursions, while isotropic values were revealed for taxa utilizing more varied arboreal repertoires. Humans, despite a frequent and predictable loading environment associated with their use of bipedalism, showed relatively isotropic values. This study highlights the confounding factors that influence trabecular microarchitecture and consequently limit its utility as a method for investigating locomotor adaptation.

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39

Fridman, Y., S. Strauss, G. Horev, M. Ackerman-Lavert, A. Reiner-Benaim, B. Lane, R. S. Smith, and S. Savaldi-Goldstein. "The root meristem is shaped by brassinosteroid control of cell geometry." Nature Plants 7, no. 11 (November 2021): 1475–84. http://dx.doi.org/10.1038/s41477-021-01014-9.

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AbstractGrowth extent and direction determine cell and whole-organ architecture. How they are spatio-temporally modulated to control size and shape is not well known. Here we tackled this question by studying the effect of brassinosteroid (BR) signalling on the structure of the root meristem. Quantification of the three-dimensional geometry of thousands of individual meristematic cells across different tissue types showed that the modulation of BR signalling yields distinct changes in growth rate and anisotropy, which affects the time that cells spend in the meristem and has a strong impact on the final root form. By contrast, the hormone effect on cell volume was minor, establishing cell volume as invariant to the effect of BR. Thus, BR has the highest effect on cell shape and growth anisotropy, regulating the overall longitudinal and radial growth of the meristem, while maintaining a coherent distribution of cell sizes. Moving from single-cell quantification to the whole organ, we developed a computational model of radial growth. The simulation demonstrates how differential BR-regulated growth between the inner and outer tissues shapes the meristem and thus explains the non-intuitive outcomes of tissue-specific perturbation of BR signalling. The combined experimental data and simulation suggest that the inner and outer tissues have distinct but coordinated roles in growth regulation.

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40

Zhang, Gong Ting, Zhi Wang Zheng, and Jun Chang. "Effect of Coiling Temperature and Cold Rolling Reduction on Planar Anisotropy of Ti-Alloyed Low Carbon Steel." Applied Mechanics and Materials 576 (June 2014): 161–65. http://dx.doi.org/10.4028/www.scientific.net/amm.576.161.

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The effects of coiling temperature and cold rolling reduction on planar anisotropy of Ti-alloyed low carbon steel were investigated. The results show that as the coiling temperature increases from 509°C to 633°C, the strength and elongation have little change, and the planar anisotropy trends to decrease. When coiling at 580°C to 640°C, the value of planar anisotropy index (△r) can be reduced to no more than 0.15. As the total cold rolling reduction increasing from 55% to 85%, the plastic strain ratio values (r-values) perpendicular to rolling direction increase firstly, then decrease; the change regulation of rolling direction is reverse, and the values of 45°direction nearly have no change. And the planar anisotropy can reach 0.07 as cold rolling at 75%.

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41

ARAUJO, R. P., and D. L. S. McELWAIN. "A linear-elastic model of anisotropic tumour growth." European Journal of Applied Mathematics 15, no. 3 (June 2004): 365–84. http://dx.doi.org/10.1017/s0956792504005406.

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This paper examines the effect of anisotropic growth on the evolution of mechanical stresses in a linear-elastic model of a growing, avascular tumour. This represents an important improvement on previous linear-elastic models of tissue growth since it has been shown recently that spatially-varying isotropic growth of linear-elastic tissues does not afford the necessary stress-relaxation for a steady-state stress distribution upon reaching a nutrient-regulated equilibrium size. Time-dependent numerical solutions are developed using a Lax-Wendroff scheme, which show the evolution of the tissue stress distributions over a period of growth until a steady-state is reached. These results are compared with the steady-state solutions predicted by the model equations, and key parameters influencing these steady-state distributions are identified. Recommendations for further extensions and applications of this model are proposed.

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42

Jiang, Shuai, Anke Kaltbeitzel, Minghan Hu, Oksana Suraeva, Daniel Crespy, and Katharina Landfester. "One-Step Preparation of Fuel-Containing Anisotropic Nanocapsules with Stimuli-Regulated Propulsion." ACS Nano 14, no. 1 (December 30, 2019): 498–508. http://dx.doi.org/10.1021/acsnano.9b06408.

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43

Mohamed, Junaith S., Michael A. Lopez, Gregory A. Cox, and Aladin M. Boriek. "Anisotropic regulation of Ankrd2 gene expression in skeletal muscle by mechanical stretch." FASEB Journal 24, no. 9 (May 4, 2010): 3330–40. http://dx.doi.org/10.1096/fj.10-158386.

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44

Nelson, Kevin S., Zia Khan, Imre Molnár, József Mihály, Matthias Kaschube, and Greg J. Beitel. "Drosophila Src regulates anisotropic apical surface growth to control epithelial tube size." Nature Cell Biology 14, no. 5 (March 25, 2012): 518–25. http://dx.doi.org/10.1038/ncb2467.

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45

Zhang, Haihui, Feng Lin, Jianyong Huang, and Chunyang Xiong. "Anisotropic stiffness gradient-regulated mechanical guidance drives directional migration of cancer cells." Acta Biomaterialia 106 (April 2020): 181–92. http://dx.doi.org/10.1016/j.actbio.2020.02.004.

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46

Abad, Ursula, Massimiliano Sassi, and Jan Traas. "Flower development: from morphodynamics to morphomechanics." Philosophical Transactions of the Royal Society B: Biological Sciences 372, no. 1720 (March 27, 2017): 20150545. http://dx.doi.org/10.1098/rstb.2015.0545.

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The shoot apical meristem (SAM) is a small population of stem cells that continuously generates organs and tissues. We will discuss here flower formation at the SAM, which involves a complex network of regulatory genes and signalling molecules. A major downstream target of this network is the extracellular matrix or cell wall, which is a local determinant for both growth rates and growth directions. We will discuss here a number of recent studies aimed at analysing the link between cell wall structure and molecular regulation. This has involved multidisciplinary approaches including quantitative imaging, molecular genetics, computational biology and biophysics. A scenario emerges where molecular networks impact on both cell wall anisotropy and synthesis, thus causing the rapid outgrowth of organs at specific locations. More specifically, this involves two interdependent processes: the activation of wall remodelling enzymes and changes in microtubule dynamics. This article is part of the themed issue ‘Systems morphodynamics: understanding the development of tissue hardware’.

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47

Lavallée, Yan, Takahiro Miwa, James D. Ashworth, Paul A. Wallace, Jackie E. Kendrick, Rebecca Coats, Anthony Lamur, et al. "Transient conduit permeability controlled by a shift between compactant shear and dilatant rupture at Unzen volcano (Japan)." Solid Earth 13, no. 5 (May 10, 2022): 875–900. http://dx.doi.org/10.5194/se-13-875-2022.

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Abstract. The permeability of magma in volcanic conduits controls the fluid flow and pore pressure development that regulates gas emissions and the style of volcanic eruptions. The architecture of the permeable porous structure is subject to changes as magma deforms and outgasses during ascent. Here, we present a high-resolution study of the permeability distribution across two conduit shear zones (marginal and central) developed in the dacitic spine that extruded towards the closing stages of the 1991–1995 eruption at Unzen volcano, Japan. The marginal shear zone is approximately 3.2 m wide and exhibits a 2 m wide, moderate shear zone with porosity and permeability similar to the conduit core, transitioning into a ∼ 1 m wide, highly sheared region with relatively low porosity and permeability, as well as an outer 20 cm wide cataclastic fault zone. The low-porosity, highly sheared rock further exhibits an anisotropic permeability network, with slightly higher permeability along the shear plane (parallel to the conduit margin), and is locally overprinted by oblique dilational Riedel fractures. The central shear zone is defined by a 3 m long by ∼ 9 cm wide fracture ending bluntly and bordered by a 15–40 cm wide damage zone with permeability enhanced by ∼ 3 orders of magnitude; directional permeability and resultant anisotropy could not be measured from this exposure. We interpret the permeability and porosity of the marginal shear zone to reflect the evolution of compactional (i.e. ductile) shear during ascent up to the point of rupture, which was estimated by Umakoshi et al. (2008) at ∼ 500 m depth. At this point the compactional shear zone would have been locally overprinted by brittle rupture, promoting the development of a shear fault and dilational Riedel fractures during repeating phases of increased magma ascent rate, enhancing anisotropic permeability that channels fluid flow into and along the conduit margin. In contrast, we interpret the central shear zone as a shallow, late-stage dilational structure, which partially tore the core of the spine, leaving a slight permanent displacement. We explore constraints from monitored seismicity and stick-slip behaviour to evaluate the rheological controls, which accompanied the shift from compactional toward dilational shear as magma approached the surface, and discuss their importance in controlling the permeability development of magma evolving from overall ductile to increasingly brittle behaviour during ascent and eruption.

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Damavandi, Ojan Khatib, and David K. Lubensky. "Statistics of noisy growth with mechanical feedback in elastic tissues." Proceedings of the National Academy of Sciences 116, no. 12 (February 28, 2019): 5350–55. http://dx.doi.org/10.1073/pnas.1816100116.

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Tissue growth is a fundamental aspect of development and is intrinsically noisy. Stochasticity has important implications for morphogenesis, precise control of organ size, and regulation of tissue composition and heterogeneity. However, the basic statistical properties of growing tissues, particularly when growth induces mechanical stresses that can in turn affect growth rates, have received little attention. Here, we study the noisy growth of elastic sheets subject to mechanical feedback. Considering both isotropic and anisotropic growth, we find that the density–density correlation function shows power law scaling. We also consider the dynamics of marked, neutral clones of cells. We find that the areas (but not the shapes) of two clones are always statistically independent, even when they are adjacent. For anisotropic growth, we show that clone size variance scales like the average area squared and that the mode amplitudes characterizing clone shape show a slow1/ndecay, where n is the mode index. This is in stark contrast to the isotropic case, where relative variations in clone size and shape vanish at long times. The high variability in clone statistics observed in anisotropic growth is due to the presence of two soft modes—growth modes that generate no stress. Our results lay the groundwork for more in-depth explorations of the properties of noisy tissue growth in specific biological contexts.

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Lambrev, Petar H., and Parveen Akhtar. "Macroorganisation and flexibility of thylakoid membranes." Biochemical Journal 476, no. 20 (October 28, 2019): 2981–3018. http://dx.doi.org/10.1042/bcj20190080.

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Abstract The light reactions of photosynthesis are hosted and regulated by the chloroplast thylakoid membrane (TM) — the central structural component of the photosynthetic apparatus of plants and algae. The two-dimensional and three-dimensional arrangement of the lipid–protein assemblies, aka macroorganisation, and its dynamic responses to the fluctuating physiological environment, aka flexibility, are the subject of this review. An emphasis is given on the information obtainable by spectroscopic approaches, especially circular dichroism (CD). We briefly summarise the current knowledge of the composition and three-dimensional architecture of the granal TMs in plants and the supramolecular organisation of Photosystem II and light-harvesting complex II therein. We next acquaint the non-specialist reader with the fundamentals of CD spectroscopy, recent advances such as anisotropic CD, and applications for studying the structure and macroorganisation of photosynthetic complexes and membranes. Special attention is given to the structural and functional flexibility of light-harvesting complex II in vitro as revealed by CD and fluorescence spectroscopy. We give an account of the dynamic changes in membrane macroorganisation associated with the light-adaptation of the photosynthetic apparatus and the regulation of the excitation energy flow by state transitions and non-photochemical quenching.

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50

Boone, Megann A., Cenny Taslim, Jesse C. Crow, Julia Selich-Anderson, Andrea K. Byrum, Iftekhar A. Showpnil, Benjamin D. Sunkel, et al. "The FLI portion of EWS/FLI contributes a transcriptional regulatory function that is distinct and separable from its DNA-binding function in Ewing sarcoma." Oncogene 40, no. 29 (June 18, 2021): 4759–69. http://dx.doi.org/10.1038/s41388-021-01876-5.

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AbstractEwing sarcoma is an aggressive bone cancer of children and young adults defined by the presence of a chromosomal translocation: t(11;22)(q24;q12). The encoded protein, EWS/FLI, fuses the amino-terminal domain of EWS to the carboxyl-terminus of FLI. The EWS portion is an intrinsically disordered transcriptional regulatory domain, while the FLI portion contains an ETS DNA-binding domain and two flanking regions of unknown function. Early studies using non-Ewing sarcoma models provided conflicting information on the roles of each domain of FLI in EWS/FLI oncogenic function. We therefore sought to define the specific contributions of each FLI domain to EWS/FLI activity in a well-validated Ewing sarcoma model and, in doing so, to better understand Ewing sarcoma development mediated by the fusion protein. We analyzed a series of engineered EWS/FLI mutants with alterations in the FLI portion using a variety of assays. Fluorescence anisotropy, CUT&RUN, and ATAC-sequencing experiments revealed that the isolated ETS domain is sufficient to maintain the normal DNA-binding and chromatin accessibility function of EWS/FLI. In contrast, RNA-sequencing and soft agar colony formation assays revealed that the ETS domain alone was insufficient for transcriptional regulatory and oncogenic transformation functions of the fusion protein. We found that an additional alpha-helix immediately downstream of the ETS domain is required for full transcriptional regulation and EWS/FLI-mediated oncogenesis. These data demonstrate a previously unknown role for FLI in transcriptional regulation that is distinct from its DNA-binding activity. This activity is critical for the cancer-causing function of EWS/FLI and may lead to novel therapeutic approaches.

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