Reversible Morphological Changes Research Articles

Effects of structural remodelling on gill physiology.

The complex relationships between the structure and function of fish gills have been of interest to comparative physiologists for many years. Morphological plasticity of the gill provides a dynamic mechanism to reversibly alter its structure in response to changes in the conditions experienced by the fish. The best known example of gill remodelling is the growth or retraction of cell masses between the lamellae, a rapid process that alters the lamellar surface area that is exposed to the water (i.e. the functional lamellar surface area). Decreases in environmental O2 availability and/or increases in metabolic O2 demand stimulate uncovering of the lamellae, presumably to increase the capacity for O2 uptake. This review addresses four questions about gill remodelling: (1) what types of reversible morphological changes occur; (2) how do these changes affect physiological function from the gill to the whole animal; (3) what factors regulate reversible gill plasticity; and (4) is remodelling phylogenetically widespread among fishes? We address these questions by surveying the current state of knowledge of gill remodelling in fishes, with a focus on identifying gaps in our understanding that future research should consider.

On the suitability of the α‐relaxation as novel trigger for a shape memory polymer

AbstractShape memory polymers typically utilize the glass transition or melting temperature to switch from one shape to another. The goal of this work is to check if the α‐relaxation, which is attributed to the migration of chains through lamellar crystals, can be utilized as novel switch for any crosslinkable semi‐crystalline thermoplastic. Using cross‐linked low‐density polyethylene (x‐LDPE) as an example, it is shown that the α‐relaxation is indeed suitable as switch, when the polymer is crystallized under strain to an intermediate shape. It is demonstrated that post‐stretching at a temperature between the α‐relaxation and the melting temperature, followed by subsequent cooling to room‐temperature switches x‐LDPE from the intermediate to a temporary shape and that reheating to this temperature initiates the retraction back to the intermediate shape. Switching between intermediate and temporary shapes is shown to be accompanied by a reversible change in morphology.

Unbiased Morphometric Assessment of Red Blood Cell Storage Lesion in the Presence of Shear-Induced Stomatocytes

Introduction: Red blood cells (RBCs) undergo progressive biochemical and morphological changes during storage, collectively called storage lesion. The quality of red cell concentrates (RCCs) is typically assessed by quantifying hemolysis. An assessment of morphological changes, associated with low quality RBCs, could give an additional indication of the safety and efficacy of the concentrates. The current standard for determining morphological changes is a manual, laborious, and subjectively biased microscopic process that limits the number of cells that can be examined. When using alternative methods like flow cells, flow and shear-induced morphologies affecting especially stomatocyte morphologies must be taken into account. We already established an automated flow morphometric RBC analysis system as an alternative to manual microscopic evaluation. The goal of the present work is to obtain a robust, automated, morphology-related signal (lesion index) quantifying RBC storage lesion in a laminar flow channel under conditions similar to stasis that is not affected by shear-induced reversible morphology changes. Methods: We use a convolutional neural network (CNN) for high throughput classification of RBCs. We analyzed the morphological changes of 5 RCCs over a period of 12 weeks and classified RBC morphologies, including such that are degradation-induced and reversible. We introduce a lesion index to denote the percentage of irreversible spherical morphologies, known to reduce the post-transfusion survival of erythrocytes. We further addressed shear-induced stomatocyte morphologies in laminar flow and whether these affect CNN-based RBC classification. Results: Our flow morphometry system achieves a high-resolution classification comprising nine morphological classes with an excellent overall accuracy of 92% and F1 scores between 84% and 97%. We generate strong evidence that the morphological lesion index can predict the hemolysis level in RCCs during storage. The power of this new classification technique allowed it, for the first time, to detect and measure the lateral concentration gradient of stomatocytes in a conventional flow chamber. Importantly, we show that reversible shear rate-induced morphologies, typical for microfluidic systems, bear no influence on the lesion index. Conclusion: Flow morphometry combined with evaluation by a CNN allows to reliably assess RBC storage lesion and thus concentrate quality. Additionally, this method reduces the need for complex laboratory procedures.

Excess microtubule and F-actin formation mediates shortening and loss of primary cilia in response to a hyperosmotic milieu.

The primary cilium is a small organelle protruding from the cell surface that receives signals from the extracellular milieu. Although dozens of studies have reported that several genetic factors can impair the structure of primary cilia, evidence for environmental stimuli affecting primary cilia structures is limited. Here, we investigated an extracellular stress that affected primary cilia morphology and its underlying mechanisms. Hyperosmotic shock induced reversible shortening and disassembly of the primary cilia of murine intramedullary collecting duct cells. The shortening of primary cilia caused by hyperosmotic shock followed delocalization of the pericentriolar material (PCM). Excessive microtubule and F-actin formation in the cytoplasm coincided with the hyperosmotic shock-induced changes to primary cilia and the PCM. Treatment with a microtubule-disrupting agent, nocodazole, partially prevented the hyperosmotic shock-induced disassembly of primary cilia and almost completely prevented delocalization of the PCM. An actin polymerization inhibitor, latrunculin A, also partially prevented the hyperosmotic shock-induced shortening and disassembly of primary cilia and almost completely prevented delocalization of the PCM. We demonstrate that hyperosmotic shock induces reversible morphological changes in primary cilia and the PCM in a manner dependent on excessive formation of microtubule and F-actin.

Photoresponsive Block Copolymer Nanostructures through Implementation of Arylazopyrazoles.

Responsive nanomaterials that can undergo reversible changes in morphology are interesting for the development of functional materials that interact with and respond to their environment. Amphiphilic block copolymers are well-known for their ability to create a wide range of supramolecular nanostructures in solution. Arylazopyrazoles (AAPs) are versatile molecular photoswitches, which change their configuration and hydrophobicity upon irradiation with UV light (365 nm, Z isomer, less hydrophobic) and green light (520 nm, E isomer, more hydrophobic). In this work, photoswitchable block copolymers containing arylazopyrazole tetraethylene glycol methacrylate (AAPMA) and oligo(ethylene glycol) methacrylate (OEGMA) forming amphiphilic POEGMA-b-PAAPMA with varying block lengths are prepared by RAFT polymerization. The photochemical properties of AAP persist in the polymers. Due to their amphiphilic structure, the polymers self-assemble into supramolecular morphologies in water. Remarkably, photoisomerization results in a reversible change in the self-assembly behavior. Specifically, spherical and cylindrical micelles are observed for POEGMA33-b-PAAPMA47 when illuminated with green or UV light during assembly. Furthermore, the morphology of assembled structures can be reversibly switched by subsequent irradiation with UV and green light.

Unilateral nasal obstruction mediates reversible morphological and phenotypic changes in masticatory muscles of growing rats.

Mouth breathing as a result of nasal obstruction affects craniofacial growth and development. This study aimed to investigate the effects of unilateral nasal obstruction and its recovery, along with the role of nitric oxide (NO) in masticatory muscle physiology. Forty-eight 4-week-old male rats were divided into control and experimental groups. The five experimental groups were subjected to left-sided nasal obstruction by suturing the external nostril, and the sutures were removed after 1, 3, 5, 7, or 9 weeks to allow for varying recovery periods. We assessed morphological changes in masseter, temporalis, and digastric muscle, by examining cross-sectional area (CSA) and myosin heavy chain (MHC) isoform composition of muscle fibers. Reverse transcription-quantitative real-time polymerase chain reaction to measure messenger RNA (mRNA) levels for tumor necrosis factor-α (TNF-α), glucose transporter 4 (GLUT4), and neuronal nitric oxide synthase (nNOS) were conducted. The SpO2, CSA, and fibers showing MHC-2b isoforms were significantly lower, while RT-PCR showed higher mRNA levels in TNF-α and nNOS, and a decrease in GLUT4 mRNA in the jaw-closing muscles in the long-term nasal obstruction groups than that in the control group. The study findings should be interpreted cautiously because of the functional differences between rodents and humans in terms of respiratory mechanisms. Unilateral nasal obstruction affects the morphology and contractile characteristics of the rat masticatory muscles during development, with possible involvement of NO in muscle hypofunction. These changes may revert to baseline levels if the nasal obstruction is eliminated before puberty in rats.

Visual Improvement Following Glaucoma Surgery

Introduction : Glaucoma is a progressive optic neuropathy and a leading cause of irreversible blindness. The aim of glaucoma treatment is to slow progression and minimize the risk of further damage, not to expect functional improvement. We report the case of a patient who experienced an improvement in vision following glaucoma surgery and review the literature regarding this phenomenon.
 Case Illustration : A 66-year old female presented with vision loss in the left eye that could only perceive finger counting in one meter. Her intraocular pressure (IOP) measured 51,8 mmHg and she was found to have primary open angle glaucoma. Medical treatment was commenced and she underwent a successful trabeculectomy. Unexpectedly she experienced improvement in vision after treatment. At her recent visit visual acuity was 6/30 in the affected eye.
 Discussion : Although the mechanism of improved vision cannot be proven it is likely that successful lowering of IOP resulted in some reversal of retinal ganglion cell dysfunction. Some evidence explained that retinal ganglion cells damaged by glaucoma might undergo a period of reversible dysfunction preceding cell death. Furthermore, reversible changes in optic nerve head morphology have been reported following reduction of intraocular pressure. These observations suggest that certain structural and functional improvements may in fact be possible in some patients. The changes of anterior chamber depth, corneal radius of curvature, corneal thickness or corneal edema could be considered as other factors which influence this improvement.
 Conclusion : Functional improvements may occur following trabeculectomy. Glaucoma surgery should be offered early, and considered even in those with reduced visual acuity.

The balance of survival: Comparative drought response in wild and domesticated tomatoes

Plants have the ability to undergo reversible behavioral, morphological, or physiological changes in response to environmental conditions. This plasticity enables plants to cope with uncertain environmental conditions, such as drought. A primary plastic trait is the rate of stomatal response to changes in ambient conditions, which determines the amount of water lost via transpiration, as well as levels of CO2 absorption, growth, and productivity. Here, we examined the differences between domesticated (S. lycopersicum cv. M82) and wild tomato (S. pennellii) species and their responses to drought stress. The plants were grown in pots in a functional phenotyping platform (FPP) in a semi-controlled environment greenhouse. We found that the domesticated tomato had a higher transpiration rate (E) and higher stomatal conductance (gs). The domesticated tomato also had greater biomass and greater leaf area under drought conditions, as compared to the wild tomato. Despite the domesticated tomato's higher E and higher gs, there was no difference between the photosynthetic rates (An) of the two lines. Moreover, the wild tomato had a higher maximum rate of rubisco activity (Vcmax), which might explain its greater leaf level and whole canopy water-use efficiency. The domesticated tomato's higher E and greater leaf area led to its earlier exposure to drought stress, as compared to the wild tomato, which maintained higher levels of soil water, enabling it to maintain steady rates of whole-canopy stomatal conductance (gsc) for extended periods. The wild tomato was also more sensitive to soil water availability and lowered its maximum transpiration rate (Emax) at a higher soil-water-content (SWC) level compared to the domesticated species. Our results suggest that the domestication of tomatoes favored morphological/anatomical performance traits over physiological efficiency.

Unknown QRS Morphology Change at Peak Exercise: To Stop or to Continue?

Electrocardiogram changes during stress tests are well standardized and understood. We present and explain a reversible QRS morphology change at peak exercise previously unreported. (Level of Difficulty: Intermediate.)

Characterization of open chromatin in response to cold reveals transcription factor association with preferred binding distances in cassava

Cassava is a tropical root crop that is sensitive to low temperature. While the transcriptome for cold-responsive genes has been extensively studied, information on their regulation is largely unavailable. Here, we conducted assays of plant morphology, the transcriptome, and open chromatin in cassava under moderate cold stress (10 ℃). We observed reversible morphological changes in cassava plants under continuous cold stress, in which plants showed wilting of the apical leaf blade and petiole at 5 h and recovery at 48 h. Consistently, distinct expressional dynamics for genes in response to cold were detected at 5 h and 48 h in both tissues. We examined the genome-wide DNase I-hypersensitive sites (DHSs) and their dynamics using cold-treated leaf blades and petioles. We revealed that cold-induced DHSs (coiDHSs) substantially differed among tissues and treatments. However, the putative coiDHS-derived transcription factors (TFs) largely co-occurred across tissues and treatments, and 61 TFs commonly shared by all samples were isolated. A putative functional network with 30 interconnected TFs was created. The frequent empirical interactions among these TFs indicate their roles in the cold response. Notably, we found that the two pairs of known cold-responsive TFs AGL20-RGA and ERF5-ERF105 showed highly frequent co-occurrence in coiDHSs. Moreover, the binding-site distances differed among TF pairs or samples, indicating that there are preferred distances between cooperative TFs and that such distances may depend on biological conditions. The identification of conserved TFs and their cooperativity provides valuable information for elucidating the transcriptional networks underlying cold gene expression in cassava.

The Effect of Oral Isotretinoin Therapy on Meibomian Gland Characteristics in Patients with Acne Vulgaris.

The aim of the study was to determine the effect of oral isotretinoin therapy on the functional and morphological condition of the anterior segment of the eye, with particular emphasis on the meibomian glands. Twenty-four patients (48 eyes) with a diagnosis of acne vulgaris were involved in the survey. All patients underwent a thorough ophthalmological examination at three time points: before therapy, 3months after the start of therapy, and 1month after the completion of isotretinoin therapy. The physical examination included the following elements: blink rate, analysis of the lid margin abnormality score (LAS), tear film break-up time (TFBUT) and Schirmer's test, meibomian gland loss (MGL), and the evaluation of the meibum quality score (MQS) and meibum expressibility score (MES). Additionally, the total score of an ocular surface disease index (OSDI) questionnaire was analysed. In comparison with pretreatment values, significant increases in OSDI during and after the treatment (p = 0.003 and p = 0.004, respectively) were observed. Substantial deterioration during the treatment was observed for MGL (p < 0.0001), MQS (p < 0.001) and LAS (p < 0.0001), while an improvement in those parameters after isotretinoin cessation was observed (p = 0.006, p = 0.02 and p = 0.0003, respectively). The frequency of using artificial eye drops was positively associated with MGL during (Spearman's rank correlation coefficient (Rs) = + 0.31; p = 0.03) and after the cessation of the therapy (Rs = + 0.28; p = 0.04). Meibomian gland atrophy correlated significantly with MQS during (Rs = + 0.29; p = 0.04) and after treatment (Rs = + 0.38; p = 0.008). The decrease in TFBUT values correlated with increased LAS (Rs = -0.31; p = 0.03) during the course of isotretinoin usage. We found no changes in Schirmer's test or blink rates. Isotretinoin therapy leads to increased ocular complaints related to lipid tear film component dysfunction. This is due to reversible changes in meibomian gland morphology and function observed during drug usage.

Unraveling Membrane-Disruptive Properties of Sodium Lauroyl Lactylate and Its Hydrolytic Products: A QCM-D and EIS Study.

Membrane-disrupting lactylates are an important class of surfactant molecules that are esterified adducts of fatty acid and lactic acid and possess industrially attractive properties, such as high antimicrobial potency and hydrophilicity. Compared with antimicrobial lipids such as free fatty acids and monoglycerides, the membrane-disruptive properties of lactylates have been scarcely investigated from a biophysical perspective, and addressing this gap is important to build a molecular-level understanding of how lactylates work. Herein, using the quartz crystal microbalance-dissipation (QCM-D) and electrochemical impedance spectroscopy (EIS) techniques, we investigated the real-time, membrane-disruptive interactions between sodium lauroyl lactylate (SLL)-a promising lactylate with a 12-carbon-long, saturated hydrocarbon chain-and supported lipid bilayer (SLB) and tethered bilayer lipid membrane (tBLM) platforms. For comparison, hydrolytic products of SLL that may be generated in biological environments, i.e., lauric acid (LA) and lactic acid (LacA), were also tested individually and as a mixture, along with a structurally related surfactant (sodium dodecyl sulfate, SDS). While SLL, LA, and SDS all had equivalent chain properties and critical micelle concentration (CMC) values, our findings reveal that SLL exhibits distinct membrane-disruptive properties that lie in between the rapid, complete solubilizing activity of SDS and the more modest disruptive properties of LA. Interestingly, the hydrolytic products of SLL, i.e., the LA + LacA mixture, induced a greater degree of transient, reversible membrane morphological changes but ultimately less permanent membrane disruption than SLL. These molecular-level insights support that careful tuning of antimicrobial lipid headgroup properties can modulate the spectrum of membrane-disruptive interactions, offering a pathway to design surfactants with tailored biodegradation profiles and reinforcing that SLL has attractive biophysical merits as a membrane-disrupting antimicrobial drug candidate.

Bacterial filaments recover by successive and accelerated asymmetric divisions that allow rapid post-stress cell proliferation.

Filamentation is a reversible morphological change triggered in response to various stresses that bacteria might encounter in the environment, during host infection or antibiotic treatments. Here we re-visit the dynamics of filament formation and recovery using a consistent framework based on live-cells microscopy. We compare the fate of filamentous Escherichia coli induced by cephalexin that inhibits cell division or by UV-induced DNA-damage that additionally perturbs chromosome segregation. We show that both filament types recover by successive and accelerated rounds of divisions that preferentially occur at the filaments' tip, thus resulting in the rapid production of multiple daughter cells with tightly regulated size. The DNA content, viability and further division of the daughter cells essentially depends on the coordination between chromosome segregation and division within the mother filament. Septum positioning at the filaments' tip depends on the Min system, while the nucleoid occlusion protein SlmA regulates the timing of division to prevent septum closure on unsegregated chromosomes. Our results not only recapitulate earlier conclusions but provide a higher level of detail regarding filaments division and the fate of the daughter cells. Together with previous reports, this work uncovers how filamentation recovery allows for a rapid cell proliferation after stress treatment.

A hydrogen-bonded organic framework of rigidly branched fluorophore: guest-adaptive cavity and phase-dependent light emission

A non-covalent assembly of a highly branched molecule produces porous crystals supported only by weak interactions. This flexible network shows reversible morphological changes and displays fluorescence responses to external stimuli and guest uptake.

A multifunctional Schiff base with aggregation-induced enhanced emission, gelation, and mechanochromic properties for anti-counterfeiting applications

This work presents a systematic study of three closely related Schiff bases NpSB, AnSB, and PySB for their potential aggregation-induced enhanced emission, gelation, and mechanochromic properties. While aggregation-induced enhanced emission was observed in case of AnSB and PySB due to the suppression of photoinduced electron transfer; PySB also formed a stable gel in DMF‒water. Out of three Schiff bases, PySB exhibited reversible mechanochromism. Importantly, on applying pressure or a mechanical force, PySB changed its color from yellow to bright orange under the visible light while its emission wavelength shifted from 580 to 602 nm. More importantly, mechanical-force-induced changes were reversible after fuming with the vapors of CH2Cl2 or by heating at 100 °C. The mechanochromism of PySB was studied by a combination of powder X-ray diffraction, scanning electron microscope, differential scanning calorimetry, density functional theory, and nuclear magnetic resonance spectral studies. These studies concluded that the change in color and emission profile was due to change in the molecular packing of PySB after applying the pressure or mechanical force. The slippage of pyrene rings and the conversion of intramolecular H-bonding to intermolecular H-bonding resulted in the alteration of solid-state packing of PySB which was responsible for the mechanochromism. A noteworthy feature of the reversible mechanochromism of PySB was the reversible morphological changes as substantiated by the scanning electron microscope and powder X-ray diffraction studies. PySB was shown to illustrate noteworthy anti-counterfeiting and pressure-induced applications.

Light-Triggered Manipulations of Droplets All in One: Reversible Wetting, Transport, Splitting, and Merging.

Here, we establish different ways of light-triggered droplet manipulation such as reversible wetting, splitting, merging, and transport. The unique features of our approach are that the changes in the wetting properties of microscopic droplets of isotropic (oil) or anisotropic (liquid crystalline) liquids adsorbed on photoswitchable films can be triggered just by application of soft optical stimuli, which lead to dynamical, reversible changes in the local morphology of the structured surfaces. The adaptive films consist of an azobenzene-containing surfactant ionically attached to oppositely charged polymer chains. Under exposure to irradiation with light, the azobenzene photoisomerizes between two states, nonpolar trans-isomer and polar cis-isomer, resulting in the corresponding changes in the surface energy and orientation of the surfactant tails at the interface. Additionally, the local increase in the surface temperature due to absorption of light by the azobenzene groups enables diverse processes of manipulation of the adsorbed small droplets, such as the reversible increase of the droplet basal area up to 5 times, anisotropic wetting during irradiation with modulated light, and precise partition of the droplet into many small pieces, which can then be merged on demand to the desired number of larger droplets. Moreover, using a moving focused light spot, we experimentally demonstrate and theoretically explain the locomotion of the droplet over macroscopic distances with a velocity of up to 150 μm·s-1. Our findings could lead to the ultimate application of a programmable workbench for manipulating and operating an ensemble of droplets, just using simple and gentle optical stimuli.

Brain structure and neurocognitive function in two professional mountaineers during 35 days of severe normobarichypoxia.

Animal studies suggest that exposure to severe ambient hypoxia for several days may have beneficial long-term effects on neurodegenerative diseases. Because, the acute risks of exposing human beings to prolonged severe hypoxia on brain structure and function are uncertain, we conducted a pilot study in healthy persons. We included two professional mountaineers (participants A and B) in a 35-day study comprising an acclimatization period and 14 consecutive days with oxygen concentrations between 8% and 8.8%. They underwent cerebral magnetic resonance imaging at seven time points and a cognitive test battery covering a spectrum of cognitive domains at 27 time points. We analysed blood neuron specific enolase and neurofilament light chain levels before, during, and after hypoxia. In hypoxia, white matter volumes increased (maximum: A, 4.3% ± 0.9%; B, 4.5% ± 1.9%) whilst gray matter volumes (A, -1.5% ± 0.8%; B, -2.5% ± 0.9%) and cerebrospinal fluid volumes (A, -2.7% ± 2.4%; B, -5.9% ± 8.2%) decreased. Furthermore, the number (A, 11-17; B, 26-126) and volumes (A, 140%; B, 285%) of white matter hyperintensities increased in hypoxia but had returned to baseline after a 3.5-month recovery phase. Diffusion weighted imaging of the white matter indicated cytotoxic edema formation. We did not observe changes in cognitive performance or biochemical brain injury markers. In highly selected healthy individuals, severe sustained normobaric hypoxia over 2 weeks elicited reversible changes in brain morphology without clinically relevant changes in cognitive function or brain injury markers. The finding may pave the way for future translational studies assessing the therapeutic potential of hypoxia in neurodegenerative diseases.

Arterial hypertension and remodelling of the right ventricle.

In the case of long-term and physiological loads (e.g. during pregnancy or regular athletics training), reversible morphological changes occur in the heart - cardiomyocytes undergo hypertrophy; however, this is not accompanied by impairment of left ventricular function or myocyte metabolism. However, in the course of various pathological processes, as time goes by, gradually permanent morphological changes occur. These changes are referred to as remodelling of the heart muscle, which, regardless of the primary cause, can lead to the development of chronic heart failure. The study was performed on post-mortem material of 35 human hearts obtained from forensic sections and anatomopathological sections of people who died of non-cardiac causes (mainly traffic accidents, suicide attempts, strokes, acute infections); material was fixed in a 4% formalin solution. The hearts were subjected to macro- and microscopic assessment. During microscopic assessment the features of remodelling were evaluated. In vivo and echocardiographic tests, as well as macroscopic evaluation of post-mortem material, suggest the presence of some kind of right ventricular muscle remodelling; however, classic microscopic observations, presented in this study, do not provide such unambiguous evidence. Thus, the question arises: why and how the right ventricular function is disturbed, sometimes at early stages of arterial hypertension.

Dielectric spectroscopic investigation of reversible photo-induced changes in amorphous Ge2Sb2Se5 thin films

Broadband dielectric spectroscopy (BDS) was used to study thin films of Ge2Sb2Se5 exposed to low fluence UV-irradiation that resulted in thermally reversible photo-induced changes (PICs) on the film surfaces. Changes were characterized by reversible changes in film morphology and changes in the microwave scattering signature prior to and following irradiation. The PIC resulting from irradiation formed a low modulus and electrically resistive layer at the film surface. Modest heating of the photo-exposed material to about 60 °C anneals out the photo-formed layer to leave behind a very thin layer of smooth, thermally stable material at the film surface. Re-exposure of the material to UV-light recreated a foamy layer, which anneals away with modest heating over several cycles. The broadband microwave insertion loss (S21) increased with the film morphology changes after UV light exposure and decreased with thermal anneal over several cycles. These changes are correlated with transformations in the film's surface morphology and possibly structural modifications in the amorphous film. Thus, the BDS analysis provided interesting new insights into the nature of photo-induced processes in chalcogenide films, such as the electrical resistance consequences of morphological/structural changes.

Light-triggered reversible supramolecular self-assembly of azo groups-functionalized copper nanoclusters

Metal nanoclusters (NCs) have attracted much attention due to their ultrasmall sizes and unique electronic structures. In recent years, the light-induced reversible assembly of Au NCs is already reported. However, to achieve light-triggered reversible self-assembly of Cu NCs is still challenging. Herein, we prepared photoresponsive Cu NCs by using an azo-containing ligand, i.e., 3,5-dimethyl-4-(phenyldiazenyl)-1H-pyrazole) (abbreviated to Hazopz). Each nanocluster contains three Cu(I) in the core and has atomic precision (denoted as Cu3-NCs hereafter). Self-assembly of Cu3-NCs into nanofibers occurred in binary solvent mixture with toluene as a good solvent and methanol (MeOH) as a poor one. When the suspension containing the nanofibers was irradiated by UV light, the originally straight nanofibers became bent. This morphological change is mainly due to the isomerization of the peripheral azo groups of the Cu3-NCs from trans- to cis-conformation, and to a small extent ascribed to the increased solubility of the cis-conformation of the azo groups in the binary solvent. The disassembled aggregates can reassemble and the bent nanofibers can become straight again when exposed to visible light. This process can be repeated for at least three times, indicating the high reversibility of this light-triggered morphological change of Cu3-NCs. The one-dimensional self-assemblies with light-triggered, reversible morphological changes achieved in this work can be potentially used as a medium material in an optical information storage device, and can write and erase information through the irradiation of UV light and visible light.