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PubMed2000

Serial transplants of DMBA-induced mammary tumors in fischer rats as model system for human breast cancer: V. Myoepithelial-mesenchymal conversion during passaging as possible cause for modulation of pineal-tumor interaction.

An elevation of melatonin secretion parallel to an enhanced production of macrophage-derived biopterin was observed in female F344 Fischer rats bearing passage 2 serial transplants derived from a malignant mammary tumor induced by 7,12-dimethylbenz[a]anthracene (DMBA). As opposed to that both parameters were depressed at passage 12. These results indicate the presence of divergent immunoneuroendocrine interactions during different phases of tumor growth. Since these biochemical events must have their common origin in changes taking place within these tumor transplants the current histopathological study was initiated. The primary tumor used for serial transplantation was a moderately differentiated adenocarcinoma of the mammary gland showing cytokeratin-positive epithelial components located in the inner epithelial tubule layer. In addition, bland-looking round or elongated actin-positive myoepithelial cells were detected which apart from epithelial cells are known to constitute the main cellular components of the mammary ductal system which resemble smooth muscle cells both morphologically and functionally. The tumor of passage 1 showed glandular tubules, lined by an inner epithelial layer, and many nests of clear, bland-looking actin-positive myoepithelial cells lying around tubules as well as in the stroma between actin-negative epithelial elements. The tumor of passage 2 used for transplantation consisted of a chaotic mixture of epithelial carcinomatous cells, forming a few irregular small tubules or solid nests, and, predominantly, of elongated plump or spindle-shaped, "myoid" atypical myoepithelial cells with a strong actin-positive reaction and some of these cells showed a focal vimentin expression. The tumor was characterized as a carcinosarcoma. At passage 12 epithelial cells were not identified. The tumor displayed features of a pleomorphic sarcoma consisting mainly of giant cells with bizarre nuclei being cytokeratin- and desmin-negative, weakly vimentin-positive but strongly actin-positive. These results indicate that DMBA-induced mammary tumor cells in female F344 Fischer rats undergo dramatic morphological changes during serial transplantation characterized by a total loss of malignant epithelial (carcinomatous) cells and the emergence and subsequent predominance of malignant (sarcomatous) mesenchymal cells. It appears that these sarcomatous cells develop out of myoepithelial cells since atypical myoepithelial cells with a strong actin-positive reaction showed a focal vimentin expression at passage 2 indicating myofibroblastic differentiation as part of mesenchymal transition. The loss of epithelial cell elements as well as a parallel transition of myoepithelial to mesenchymal cell elements during passaging could lead to a lack of immunological recognition of these tumor transplants and to depression of melatonin. Possible mechanisms involved in these phenomena as well as the relevance of these findings for a better understanding of the role of melatonin in human mammary cancer are discussed.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1990

A combination of closely associated positive and negative cis-acting promoter elements regulates transcription of the skeletal alpha-actin gene.

The chicken skeletal alpha-actin gene promoter region provides at least a 75-fold-greater transcriptional activity in muscle cells than in fibroblasts. The cis-acting sequences required for cell type-restricted expression within this 200-base-pair (bp) region were elucidated by chloramphenicol acetyltransferase assays of site-directed Bg/II linker-scanning mutations transiently transfected into primary cultures. Four positive cis-acting elements were identified and are required for efficient transcriptional activity in myogenic cells. These elements, conserved across vertebrate evolution, include the ATAAAA box (-24 bp), paired CCAAT-box-associated repeats (CBARs; at -83 bp and -127 bp), and the upstream T+A-rich regulatory sequence (at -176 bp). Basal transcriptional activity in fibroblasts was not as dependent on the upstream CBAR or regions of the upstream T+A-rich regulatory sequence. Transfection experiments provided evidence that positive regulatory factors required for alpha-actin expression in fibroblasts are limiting. In addition, negative cis-acting elements were detected and found closely associated with the G+C-rich sequences that surround the paired CBARs. Negative elements may have a role in restricting developmentally timed expression in myoblasts and appear to inhibit promoter activity in nonmyogenic cells. Cell type-specific expression of the skeletal alpha-actin gene promoter is regulated by combinatorial and possibly competitive interactions between multiple positive and negative cis-acting elements.

Actins↗

PubMed1994

Molecular characterization of a swelling-induced chloride conductance regulatory protein, pICln.

Cells maintain control of their volume by the passage of KCl and water across their membranes, but the regulatory proteins are unknown. Expression in Xenopus oocytes of a novel protein, pICln, activated a chloride conductance. We have cloned analogs of pICln from rat heart and Xenopus ovary. pICln was identified as an abundant soluble cytosolic protein (approximately 40 kd) that does not immunolocalize with the plasma membrane. pICln was found in epithelial and cardiac cells, brain, and Xenopus oocytes, forming complexes with soluble actin and other cytosolic proteins. Monoclonal antibodies recognizing pICln blocked activation of a native hypotonicity-induced chloride conductance (ICl.swell) in Xenopus oocytes, suggesting that pICln may link actin-bound cytoskeletal elements to an unidentified volume-sensitive chloride channel. The high degree of sequence conservation and widespread expression of pICln suggest that it is an important element in cellular volume regulation.

Actins↗

PubMed1982

In vitro reconstitution of chromaffin granule-cytoskeleton interactions: ionic factors influencing the association of F-actin with purified chromaffin granule membranes.

Chromaffin granules are the secretory vesicles directly involved in exocytosis of catecholamines, enkephalins, and other components from adrenal medullary cells. The granules occupy a large portion of the cytoplasmic volume and thus may interact extensively with cytoskeletal elements such as actin. Indeed, using both sedimentation techniques and falling ball viscometry [Fowler et al: J Cell Biol 88: 388, 1981] to measure actin binding by membranes, we were able to show that chromaffin granules bind F-actin via a protein site on the membrane, and that these interactions are reversibly inhibited by raising the free calcium ion concentration to micromolar levels ([Ca++]free for half-maximal inhibition approximately 2.6 x 10(-7)M)[Fowler and Pollard: Nature 295:336, 1982]. Here, we show that F-actin-chromaffin granule interactions are unaffected by changes in pH between about pH 6.4 and 7.4 but are about 50% inhibited by raising the pH from 7.5 to 8.0. They are also 50% inhibited by increasing the KCl concentration to about 200 mM but are not significantly affected by increasing concentrations of K-glutamate up to 500 mM or by varying the MgCl2 concentration between 0 and 6 mM. The interactions between chromaffin granule membranes and F-actin are also reduced in the presence of ATP, AMP-PNP, or free pyrophosphate; cAMP and AMP are without effect. The ability of chromaffin granule membranes to interact with F-actin under conditions that may approximate the resting intracellular environment (neutral pH, low KCl, 1-2 mM MgCl2, 1 mM ATP, [Ca++]free less than 10(-7)M, 30 degrees C) suggests that these interactions may partially reconstitute naturally occurring associations between chromaffin granules and the cytoskeleton. Further, regulation of chromaffin granule membrane-actin interactions by ionic factors (pH, calcium, chloride ions, nucleotides) that vary intracellularly leads us to propose that associations between actin and the chromaffin granule membrane could influence the location and dislocation of these organelles in the cytoplasm.

Actins↗

PubMed1997

cDNA libraries from single human preimplantation embryos.

In this paper, the construction, evaluation, and application of cDNA libraries from eight unfertilized oocytes and single four-cell-, seven-cell-, and blastocyst-stage embryos are described. Rapid, reproducible, and efficient procedures for the construction of PCR-based cDNA libraries from fewer than 10 cells were first developed in small populations of fibroblast cells. The human embryo libraries display complexities sufficient (between 10(5) and 10(6) clones) to represent the entire active gene population at these early stages of human development. The ubiquitous cytoskeletal elements, beta-actin, keratin-18, and alpha-tubulin, were detected at the expected frequency. Sequencing of consecutively picked random clones, without selection, showed the presence of a variety of sequences, such as the human transposable element, LINE-1 and Alu repeat sequences, housekeeping genes, and tissue-specific genes, such as alpha-globin and FMR-1. In addition to cDNAs corresponding to known ESTs (expressed sequence tags) in the GenBank and dbEST databases, a high proportion of novel sequences were detected. Applications of the libraries to several areas of interest, such as expression of CpG-island-containing "tissue-specific" genes, developmental genes expressed in a stage-specific manner, and a search for monoallelic expression of imprinted genes, are described. The libraries are a valuable resource for the study of gene expression during human preimplantation development and obviate the need for research on the human embryos themselves.

Cells, Cultured↗

PubMed2005

Involvement of a small GTP binding protein in HIV-1 release.

BACKGROUND: There is evidence suggesting that actin binding to HIV-1 encoded proteins, or even actin dynamics themselves, might play a key role in virus budding and/or release from the infected cell. A crucial step in the reorganisation of the actin cytoskeleton is the engagement of various different GTP binding proteins. We have thus studied the involvement of GTP-binding proteins in the final steps of the HIV-1 viral replication cycle. RESULTS: Our results demonstrate that virus production is abolished when cellular GTP binding proteins involved in actin polymerisation are inhibited with specific toxins. CONCLUSION: We propose a new HIV budding working model whereby Gag interactions with pre-existing endosomal cellular tracks as well as with a yet non identified element of the actin polymerisation pathway are required in order to allow HIV-1 to be released from the infected cell.

ADP Ribose Transferases↗

PubMed1999

Molecular interactions between single-stranded DNA-binding proteins associated with an essential MCAT element in the mouse smooth muscle alpha-actin promoter.

Transcriptional activity of the mouse vascular smooth muscle alpha-actin gene in fibroblasts is regulated, in part, by a 30-base pair asymmetric polypurine-polypyrimidine tract containing an essential MCAT enhancer motif. The double-stranded form of this sequence serves as a binding site for a transcription enhancer factor 1-related protein while the separated single strands interact with two distinct DNA binding activities termed VACssBF1 and 2 (Cogan, J. G., Sun, S., Stoflet, E. S., Schmidt, L. J., Getz, M. J., and Strauch, A. R. (1995) J. Biol. Chem. 270, 11310-11321; Sun, S., Stoflet, E. S., Cogan, J. G., Strauch, A. R., and Getz, M. J. (1995) Mol. Cell. Biol. 15, 2429-2936). VACssBF2 has been recently cloned and shown to consist of two closely related proteins, Puralpha and Purbeta (Kelm, R. J., Elder, P. K., Strauch, A. R., and Getz, M. J. (1997) J. Biol. Chem. 272, 26727-26733). In this study, we demonstrate that Puralpha and Purbeta interact with each other via highly specific protein-protein interactions and bind to the purine-rich strand of the MCAT enhancer in the form of both homo- and heteromeric complexes. Moreover, both Pur proteins interact with MSY1, a VACssBF1-like protein cloned by virtue of its affinity for the pyrimidine-rich strand of the enhancer. Interactions between Puralpha, Purbeta, and MSY1 do not require the participation of DNA. Combinatorial interactions between these three single-stranded DNA-binding proteins may be important in regulating activity of the smooth muscle alpha-actin MCAT enhancer in fibroblasts.

Actins↗

PubMed1996

Elaboration of the messenger transport organizer pathway for localization of RNA to the vegetal cortex of Xenopus oocytes.

Previous studies demonstrated that there were two pathways, the messenger transport organizer (METRO) or early and the Vg1 or late, which function during stages 1 to 3 of oogenesis for the localization of RNAs at the vegetal cortex of Xenopus oocytes. In the present study we analyzed the properties of the METRO pathway, which localizes Xlsirt, Xcat2, and Xwnt11 RNAs to a specific region of the vegetal cortex during stage 1 of oogenesis. A combination of methodologies involving both fixed material and living oocytes was used to analyze RNA localization. We show that in early diplotene pre-stage 1 oocytes (25-50 microm in diameter) both endogenous and injected exogenous METRO RNAs translocated to multiple mitochondrial aggregates (pre-mitochondrial clouds) that surround the germinal vesicle (GV). However, by early stage 1 (diplotene oocytes, 50-200 microm), all three of the RNAs discriminated between the different clouds and translocated exclusively within the METRO of a single mitochondrial cloud. Therefore, in stage 1 diplotene oocytes there is a unique mechanism causing a change in the intrinsic property of the mitochondrial clouds which designates one of them as the RNA transport vehicle. During translocation through the cytoplasm Xlsirt and Xcat2 RNAs were detected associated with cytoplasmic particles of different morphologies. Additionally, we also found that the translocation of RNAs through the early or METRO pathway, unlike that of the late pathway, occurred in the absence of intact microtubule and actin microfilament cytoskeletal elements. This supports a cytoskeletal-independent model for localization of RNAs through the METRO pathway.

Actin Cytoskeleton↗

PubMed1991

Identification of single-stranded-DNA-binding proteins that interact with muscle gene elements.

A sequence-specific DNA-binding protein from skeletal-muscle extracts that binds to probes of three muscle gene DNA elements is identified. This protein, referred to as muscle factor 3, forms the predominant nucleoprotein complex with the MCAT gene sequence motif in an electrophoretic mobility shift assay. This protein also binds to the skeletal actin muscle regulatory element, which contains the conserved CArG motif, and to a creatine kinase enhancer probe, which contains the E-box motif, a MyoD-binding site. Muscle factor 3 has a potent sequence-specific, single-stranded-DNA-binding activity. The specificity of this interaction was demonstrated by sequence-specific competition and by mutations that diminished or eliminated detectable complex formation. MyoD, a myogenic determination factor that is distinct from muscle factor 3, also bound to single-stranded-DNA probes in a sequence-specific manner, but other transcription factors did not. Multiple copies of the MCAT motif activated the expression of a heterologous promoter, and a mutation that eliminated expression was correlated with diminished factor binding. Muscle factor 3 and MyoD may be members of a class of DNA-binding proteins that modulate gene expression by their abilities to recognize DNA with unusual secondary structure in addition to specific sequence.

Animals↗

PubMed2000

Cross-linking constraints on F-actin structure.

The DNase I binding loop (residues 38-52), the hydrophobic plug (residues 262-274), and the C terminus region are among the structural elements of monomeric (G-) actin proposed to form the intermonomer interface in F-actin. To test the proximity and interactions of these elements and to provide constraints on models of F-actin structure, cysteine residues were introduced into yeast actin either at residue 41 or 265. These mutations allowed for specific cross-linking of F-actin between C41 and C265, C265 and C374, and C41 and C265 using dibromobimane and disulfide bond formation. The cross-linked products were visualized on SDS-PAGE and by electron microscopy. Model calculations carried out for the cross-linked F-actins revealed that considerable flexibility or displacement of actin residues is required in the disulfide cross-linked segments to fit these filaments into model F-actin structures. The calculated, cross-linked structures showed a better fit to the Holmes rather than the refined Lorenz model of F-actin. It is predicted on the basis of such calculations that image reconstruction of electron micrographs of disulfide cross-linked C41-C374 F-actin should provide a conclusive test of these two similar models of F-actin structure.

Actins↗

PubMed1991

Phased cis-acting promoter elements interact at short distances to direct avian skeletal alpha-actin gene transcription.

Recently, site-directed mutagenesis uncovered four positive cis-acting elements in the 5' promoter region of the chicken skeletal alpha-actin gene that directs myogenic tissue-restricted expression. In this study, interactions between the four promoter sites were examined by means of a series of insertion mutations that increased the linker region between adjacent elements by roughly half or complete DNA helical turns. Unexpectedly, transcriptional activity for all three sets of linker mutants, as assayed with a chloramphenicol acetyltransferase reporter gene, was found to vary in a fashion resembling a damped sinusoid with a period of roughly 10 base pairs, where the sinusoidal maxima appeared when length was increased by half-integral number of helix turns. We present a model which states that in the undistorted wild-type 5' flanking sequence, linker domains position each of the four promoter sites on the helix face opposite that of its immediate neighbors; when any of the three linkers is increased by approximately a half-integral number of helix turns, pairs of neighboring promoter sites are brought into alignment. We propose that this is the required orientation for inducing skeletal muscle-specific promoter activity, achieved in the wild-type promoter as a result of protein-induced torsional deformation.

Actins↗

PubMed1991

Transitional elements with characteristics of both growth cones and presynaptic terminals observed in cell cultures of cerebellar neurons.

As growth cones interact with targets, they become presynaptic terminals by losing growth cone characteristics and acquiring presynaptic characteristics. Results presented here show that transitional elements can be identified in cell cultures of rat cerebellum, which have some characteristics of both growth cones and presynaptic terminals. During the first week in culture, slender growth cones have fine filopodia. Subsequently, many growth cones in contact with the polylysine substrate spontaneously enlarge and become non-motile. In transitional elements, the synaptic vesicle protein p65 extends into the peripheral domain and in some cases, extends into filopodia. Many of these transitional elements have active filopodia but show no movement over the substrate for periods of up to nine days. These transitional elements have lost the actin-rich peripheral domain of the growth cone but retain actin labelling in the filopodia. With electron microscopy, transitional elements were seen to contain accumulations of synaptic vesicles at the site of contact with the substrate. Electron microscopic immunocytochemistry showed these synaptic vesicles labelled for p65 with silver-developed gold particles. Thus, transitional elements have characteristics of both growth cones and presynaptic terminals, suggesting that they may also have functional attributes of both growth cones and presynaptic elements.

Actins↗

PubMed2002

Molecular analysis of the seasonal expression of genes coding for different functional markers of the digestive gland of the bivalve mollusk Pecten maximus (L.).

Digestive gland cells of Pecten maximus accumulate and release lipid storage according to a seasonal cycle. For the first time in molluscs, molecular probes were developed and applied to monitor the lipid accumulation and consumption cycle related to phytoplankton blooms and phenomena of cellular proliferation and apoptosis. The molecular probes consisted of glyceraldehyde-3-phosphate dehydrogenase (GPD), which is involved in the acetylation of fatty acids; aldolase, which favours the formation of pyruvate and dihydroxyacetone; actin, an essential element of the cytoskeleton that disappears during adipocyte cell transformation; and cycline B, an ubiquitous cell cycle protein. Alpha-amylase, provided by IFREMER-Brest (France), was used to relate these different events to the animal's food supply. A positive relation between GPD and aldolase gene expressions was inversely correlated with that of actin, confirming results in mammals. In P. maximus, mRNA transcripts of GPD and aldolase decrease rapidly before gamete emissions whereas those of actin increase rapidly. After gamete emission, the mRNA levels of aldolase, GPD and alpha-amylase increase, while those of actin decrease. Cycline B mRNA transcripts indicate that the period of digestive cell proliferation is initiated during winter, prior to the release of lipids into the digestive tract and apoptosis.

Actins↗

PubMed1986

Actin and myosin multigene families: their expression during the formation and maturation of striated muscle.

The initial formation of skeletal muscle fibers is accompanied by the expression of muscle-type actin and myosin genes. During subsequent maturation of muscle fibers in vivo, developmental changes in the fetal/adult isoforms of these proteins occur. Skeletal muscle-specific transcripts coding for different myosin heavy chains accumulate sequentially both in vivo and in vitro. A genetic analysis demonstrates that these genes are clustered, implicating cis-acting regulatory factors. In contrast, actin and myosin light chain genes are dispersed in the mouse genome. These gene families show a different developmental "strategy": Genes expressed in adult cardiac tissue are coexpressed with the corresponding skeletal muscle sequence during fetal development. This phenomenon also occurs in adult tissue. Under conditions of cardiac overload, adult rat hearts accumulate skeletal actin mRNA and cardiac actin transcripts. In some mouse lines, a mutant cardiac actin gene locus is present. The presence of a second active upstream promoter at this locus depresses transcription of the bone fide gene, resulting in low levels of mature cardiac actin mRNA. In this situation skeletal actin gene transcripts accumulate. Genes expressed in the same fetal or adult muscle phenotype are not linked, suggesting that their coexpression is regulated by transacting factors. The promoter regions of such genes in the mouse have no common characteristics of primary structure with the exception of an E1A-type enhancer core sequence, which has a conserved 5' flanking element, seen for actin and myosin light chain genes. Reintroduction of these promoter regions into muscle cells provides a functional test for such potential regulatory sequences.

Actins↗

PubMed1993

The in-vitro effect of antineoplastic agents on proliferative activity and cytoskeletal components of plaque-derived smooth-muscle cells from human coronary arteries.

BACKGROUND: Restenosis after successful percutaneous transluminal coronary angioplasty remains the major clinical problem limiting the long-term efficacy of the treatment. Recent advances in the understanding of the biology of restenosis indicate that its cause is predominantly a multifactorial stimulation of smooth-muscle cell proliferation. The aim of this study was to investigate the in-vitro effect of antineoplastic agents on smooth-muscle cells isolated from human coronary plaque material. METHODS: Atherosclerotic tissue from coronary arteries was extracted from 15 patients of both sexes by thrombendarterectomy. Cells were isolated using enzymatic disaggregation and identified to be smooth-muscle cells with fluorescent antibodies for smooth-muscle-specific alpha-actin. The antineoplastic agents cytarabine (500-0.005 micrograms/ml), doxorubicin (50-0.0005 micrograms/ml), and vincristine (10-0.0001 micrograms/ml) were added to the cultures. Six days after seeding, the cells were trypsinized and then counted. RESULTS: All three antineoplastic agents had a strong dose-dependent antiproliferative effect on cultured smooth-muscle cells. After the application of cytostatic agents, cells either became rounded or underwent complete lysis. Cytoskeletal elements, such as actin, microtubules, and vimentin, were largely altered. CONCLUSION: This investigation examined the potential role of antineoplastic therapy in the prevention of restenosis after coronary angioplasty. The development of new intravascular delivery systems, such as coated stents, may open the way for local antiproliferative strategies in interventional cardiology.

Aged↗

PubMed1997

Organogenesis and angiogenin.

Our search for an angiogenesis-inducing factor in culture medium conditioned by human colon adenocarcinoma cells (HT-29) was inspired by the 'organizer' hypothesis originally postulated by Spemann. It led us to the isolation of angiogenin, a 14 kD protein homologous to pancreatic ribonuclease and one of the most potent stimulators of blood vessel formation known. This review summarizes the properties of angiogenin, its enzymatic and three-dimensional relationship to ribonuclease A (RNase A), those aspects of its structure that are critical for its biological function, and the therapeutic potential of angiogenin inhibition. Despite having the same arrangement of catalytic residues as RNase A, angiogenin has very low enzymatic activity. It lacks one of the four disulphide loops of RNase A; instead, the corresponding residues form part of a cell binding region. Both the catalytic activity and cell binding site are essential for angiogenesis. Angiogenin binds to cell-surface actin in confluent endothelial cells and to an as yet uncharacterized receptor on proliferating cells. Internalization and translocation to the nucleolus are also required for activity. Inhibitors of angiogenin can block angiogenesis in vitro and prevent tumour growth in vivo. Thus, a noncytotoxic neutralizing monoclonal antibody prevents the establishment of HT-29 human tumour xenografts in up to 65% of treated athymic mice. In those tumours that develop, the number of vascular elements is reduced. Actin also prevents the establishment of tumours while exhibiting no toxic effects at daily doses > 50 times the molar amount of circulating mouse angiogenin. These antagonists also inhibit the appearance of tumours derived from two other human tumour cell lines. Inhibition of the action of angiogenin may prove to be an effective therapeutic approach for the treatment of malignant disease.

Angiogenesis Inducing Agents↗

PubMed1999

[Regulation of the microtubule-dependent process formation. A review based on a comparison between the neuron and the renal glomerular podocyte].

Microtubular cytoskeletons play a crucial role in the morphogenesis of process-bearing cells, such as the neuron and the renal glomerular podocyte. Microtubules are bundled and stabilized by various microtubule-associated proteins, providing a mechanical basis to maintain the deviated morphology of cell processes. To support the process morphology, microtubules are also associated with other cytoskeletal elements such as actin and intermediate filaments. The microtubular polarity is uniformly plus-end-distal in neuronal axons, whereas in dendrites as well as in podocytes, the polarity is revealed to be non-uniform (i.e., both plus-end-distal and minus-end-distal microtubules are present in cell processes). Recently, this non-uniformity is reported to be established by a microtubule-dependent motor protein. Motor proteins are capable to drive the intracellular transport of cytoskeletal elements in addition to that of membrane vesicles. It is still an open question whether cytoskeletal elements are transported along cell processes as subunits or as polymers.

Animals↗

PubMed1981

Cytoskeletal and muscle-like elements in cochlear hair cells.

Monospecific antibodies to actin and to tubulin were used as immunofluorescent probes to evaluate the distribution of microtubules and actin filaments in the organ of Corti in mouse and guinea pig. The results indicate that in cochlear receptor cells actin and actin filaments as well as tubulin and microtubules are integral cytoskeletal elements. The presence of actin suggests a possible contractile mechanism within the sensory cilia whereas tubulin is thought to play an important role in the stability of sensory cells. Both proteins are discussed to form structural elements required for the mechano-chemical coupling in hearing.

Actins↗