Biomechanical and biochemical assessment of YB-1 expression in melanoma cells

Malignant melanoma is the most lethal form of skin cancer; its incidence has increased over the last five decades. Y-box binding protein 1 (YB-1) plays a prominent role in mediating metastatic behavior by promoting epithelial-to-mesenchymal transition (EMT) processes. Migratory melanoma cells exhibit two major phenotypes: elongated mesenchymal or rounded amoeboid. The actomyosin cytoskeleton is key in both phenotypes, but intermediate filaments also undergo a significant rearrangement process, switching from cytokeratin-rich to vimentin and nestin-rich network. In this study, we aimed to investigate to what extent YB-1 impacts the biomechanical (cell stiffness) and biochemical aspects of melanoma cells and their cytoskeleton. To this end, we subjected A375 YB-1 knock-out and parental cells to atomic force microscopy investigations (stiffness determination), immunolabelling, and proteome analysis. We found that YB-1 expressing cells were significantly stiffer compared to the corresponding YB-1 knock-out cell line. Proteomic analysis revealed that expression of YB-1 results in a strong co-expression of nestin, vimentin, fascin-1, and septin-9. In the YB-1 knock-out nestin was completely depleted, but zyxin was strongly upregulated. Collectively, our results showed that YB-1 knock-out acquires some characteristics of mesenchymal phenotype but lacks important markers of malignancy and invasiveness such as nestin or vimentin. We posit that there is an association of YB-1 expression with an amoeboid phenotype, which would explain the increased migratory capacity.

The Atomic Rearrangement of GaN-Based Multiple Quantum Wells in H2/NH3 Mixed Gas for Improving Structural and Optical Properties

In this work, three GaN-based multiple quantum well (MQW) samples are grown to investigate the growth techniques of high-quality MQWs at low temperature (750 °C). Instead of conventional temperature ramp-up process, H2/NH3 gas mixture was introduced during the interruption after the growth of InGaN well layers. The influence of hydrogen flux was investigated. The cross-sectional images of MQW via transmission electron microscope show that a significant atomic rearrangement process happens during the hydrogen treatment. Both sharp interfaces of MQW and homogeneous indium distribution are achieved when a proper proportion of hydrogen was used. Moreover, the luminescence efficiency is improved strongly due to suppressed non-radiative recombination process and a better homogeneity of MQWs. Such kind of atomic rearrangement process is mainly caused by the larger diffusion rate of gallium and indium adatoms in H2/NH3 mixed gas, which leads to a lower potential barrier energy to achieve thermodynamic steady state. However, when excessive hydrogen flux is introduced, the MQW will be partly damaged, and the luminescence performance will deteriorate.

DFT study on the gold(I)-catalyzed cycloaddition and rearrangement reactions of allene-containing allylic silyl ether

The DFT calculation of the B3LYP level was carried out to explore the reaction mechanism of the synthesis of spirocyclo[4, 5]decane skeleton by gold-catalyzed allenyl compounds. The more accurate energy under the CH3CN solvent in the experiment is calculated by the single point energy of the SMD model. Computational studies have shown that the reaction consists of three main steps: intramolecular cycloaddition of the end group carbon atoms of allenyl and vinyl groups, the semipinacol rearrangement process in which the four-membered ring is reconstructed into the five-membered ring, the elimination reaction releases the catalyst and obtains the product. The calculation results show that Zheng et al. reported that the gold-catalyzed synthesis reaction can easily occur under the experimental conditions due to its low activation free energy (12.42–16.79 kcal/mol). Furthermore, it was found that the MOMO(CH2)2 substituent has higher reactivity than the corresponding reactant of the phenyl substituent.

Photoinduced transition-metal and external photosensitizer free cross-coupling of aryl triflates with trialkyl phosphites

Photoinduced phosphonation of aryl triflates with trialkyl phosphites via a tandem single-electron-transfer, C–O bond cleavage and Arbuzov rearrangement process in the absence of transition-metal and external photosensitizer is reported herein....

Unique intramolecular oxidative rearrangement N-nitrosation mechanism of non-heam iron-containing enzyme SznF

ABSTRACTNon-heam iron-dependent enzyme SznF catalyzes a critical step of the L-arginine derived guanidine group rearrangement to produce the N-nitrosourea pharmacophore in the process of SZN biosynthesis. The intramolecular oxidative rearrangement process is accomplished in the Fe(II)-containing active site located at the cupin domain of SznF, with which the catalytic mechanism remains elusive. In this work, density functional theory methods have been employed to investigate possible catalytic mechanisms of SznF. The N-nitrosation reaction in SznF was found to follow an energetically favorable pathway which includes six consecutive steps: (1) formation of FeII-superoxo species with dioxgen binding on the iron center; (2) superoxo group attacking on the Cε of substrate to form the peroxo-bridge complex; (3) Cε-Nω bond homolysis to release NωO; (4) peroxo bridge heterolytic cleavage; (5) deprotonation of by Fe-O group; (6) the couples with the NωO group and generates the N-nitroso product. The reaction proceeds in an unexpected way during which the electrons shuttle among two NO groups of the substrate and the peroxo moiety to promote Cε-Nω bond homolysis and O-O bond heterolysis sequentially without generating high-valent Fe-O species, which is distinct from any known reactions catalyzed by the iron-containing enzyme. The unusual mechanism of SznF shed light on the area of enzymatic N-nitrosation reactions.

Synthesis of Tryptamines through a Novel Brønsted Acid Mediated Tandem Reaction Initiated by α-Iminol Rearrangement of Transient 2-Substituted 2-Hydroxycyclobutylimines

A novel Brønsted acid promoted condensation reaction between a primary aniline and 2-hydroxycyclobutanone provides access to diverse tryptamine derivatives in moderate to good yields. The proposed mechanism involves an α-iminol rearrangement, ring expansion, ring closure, and a depart-and-return rearrangement process.

CITRA EKSOTIK DALAM NOVEL RONGGENG DUKUH PARUK

Imaging of a discourse in the paradigm of postcolonialism is closely related to the issue of domination and subordination in terms of reference to imperialism or capitalization. The imagery is a project that develops special perceptions about "foreign" (East) regions. This project presupposes that the "foreign" (East) region is exotic "uncivilized" regions, standardized in a special "understanding", whose main purpose is to separate or dissolve it ("tame" the "foreign" region), so that different from or being "civilized". One area that is strongly embedded in this project is literature, with the novel as an aesthetic object. In connection with this issue, this article reveals how the East is presented in its exotic image, so how the image represents an ambivalent relationship between the East (colonized) and the West (invaders), especially in the Ronggeng Dukuh Paruk (RDP) novel by Ahamad Tohari.The results of the study show that the RDP novel is an urgent medium related to the conditions of postcoloniality. The postcoloniality is meant not only that the narrative that is displayed is the essence of what is obtained from the author about the exotic world region (the nature of Paruk dukuh) with all the signs attached to it, narration is also used as an affirmation of identity and historical existence, in the context of civilized culture. The culture in question is the source of identity that is championed as a filter and lifter, for the community that has been known and thought about, as an invitation for emancipation. Power and ability to tell stories, in this case, are used as weapons of the author in hopes of inspiring readers. The expected result is the hegemonic reader of the discourse displayed in the work of the author.In the post-colonial context, this method is inseparable from a combination where political and ideological power is interrelated, where the image represented is always still signifying the "emancipation" power relationship between the West and the East. However, like ideology, imaging must be realized other than as originating from and relating to material conditions and material effects, it is also a misrepresentation of reality and in its rearrangement process. Therefore, the potential, possibilities, and certain visions that follow, are full of content, values, or strategies for "mastering" (power). Especially in the Ronggeng Dukuh Paruk novel by Ahamad Tohari, exotic images give rise to ambivalent meanings for emancipation efforts (West to East).

Neutral cyclic sp2–sp3 and sp3–sp3 diboranes from N,N′-dicyclohexylcarbodiimide insertion into 1,2-dichlorodiboranes(4)

New derivatives of sp2–sp3 and sp3–sp3 diboranes were prepared via a carbodiimide-induced rearrangement process.

The synthetic versatility of the Tiffeneau–Demjanov chemistry in homologation tactics

The Tiffeneau–Demjanov rearrangement can be regarded as an interesting alternative to the more common semi-pinacol transposition. It is usually employed for ring extension but, under specific conditions, it can also be used for ring contraction. Compared to other techniques, such as the Demjanov rearrangement or homologations with diazo compounds, the Tiffeneau–Demjanov pathway presents attractive features including high yielding and selective processes. Ring enlargements follow very strict and simple rules, such as the movement of the less substituted carbon and retention of the configuration. The rearrangement process is mainly affected by steric factors, due to presence of neighbouring groups, rather than electronic ones. The ring contraction may be achieved positioning the amine within the ring, thus achieving a high level of control. Unfortunately, applications of the reaction in modern homologation chemistry are rare; therefore, the aim of the review is re-proposing to the synthetic community the versatility of this venerable reaction and thus, spurring its employment for tackling challenging homologations processes. Graphic abstract

O,O-diethyl O-[2-(dimethylamino)ethyl] phosphorothioate: structural evidence of the decomposition product and its oxalate salt

The molecular and single crystal structure of O,O-diethyl O-[2-(dimethylamino)ethyl] phosphorothioate oxalate, as determined by single crystal X-ray diffraction studies, is described for the first time; although this compound is well-known by industry and research from the mid-20th century. The known decomposition product of pure O,O-diethyl O-[2-(dimethylamino)ethyl] phosphorothioate could also be structurally characterized. Additionally, the compounds are characterized by recent analytical methods e.g. NMR. The findings of our study support the thesis that the isolated decomposition product must be a by-product of the thiono-thiolo rearrangement process of the title compound.