Rotational analysis of naphthol-aromatic ring complexes stabilized by electrostatic and dispersion interactions

For complexes involving aromatic species, substitution effects can influence the preferred geometry.

Mineralogical Criteria for Genetic Relationship of Igneous and Carbonatite Rocks of the Tomtor Massif (Siberian Platform)

The Tomtor massif, located in the north-east of the Siberian Platform, is a polychronous zonal-ring complex of alkaline ultrabasic rocks and carbonatites containing a unique deposit of Nb and REE. A comparative analysis of the typomorphic features of minerals of different types of silicate rocks and carbonatites of the Tomtor massif is given in order to establish their convergent features. In order to exclude the mutual influence of rocks formed at different times on each other, samples were taken from different dispersed independent pipe-like bodies of melteigites, a sheet body of alkaline picrites and a transverse dike of carbonatite located south of the Tomtor massif, as well as from alkaline syenites from the southern margin of the massif. It is shown that interesting convergent features are identified in the rock-forming and accessory minerals, including rare-metal ore minerals of different silicate igneous rocks and carbonatite formations. Rock-forming minerals - pyroxenes, micas, feldspars, feldspathopids, garnets, as well as basic and rare carbonates, oxide ore minerals, including Cr-containing spinelides, and sulfide and other exotic phases have such features. The confirmation of the convergence of a group of obvious high-temperature early magmatic elements-MgO, Cr, and Ni - with a group of CaO, CO2, H2O, P2O5, and Y components forming carbonatite derivatives was the most interesting nuance in this regard. Existence of such polychromous complicated ore-magmatic ring complexes as Tomtor massif indicates occurrence of intraplate deep large magma-generating hearths in lithosphere mantle. Such easily fusible hearths, conserved in lithosphere mantle of residual melts of kimberlite, alkali-picrites, carbonatite compositions, under the subsequent favorable geodynamic settings, are subject to rapid flotation, undergoing decompression melting and forming concentric-zonal platform complexes of alkali ultrabasic rocks with carbonatites

γ-TuRCs are required for asymmetric microtubule nucleation from the somatic Golgi of Drosophila neurons

Microtubules are polarised polymers nucleated by multi-protein γ-tubulin ring complexes (γ-TuRCs). Within neurons, microtubule polarity is plus-end-out in axons and mixed or minus-end-out in dendrites. Previously we showed that within the soma of Drosophila sensory neurons γ-tubulin localises asymmetrically to Golgi stacks, Golgi-derived microtubules grow asymmetrically towards the axon, and growing microtubule plus-ends are guided towards the axon and restricted from entering dendrite in a Kinesin-2-dependent manner (Mukerjee et al., 2020). Here we show that depleting γ-TuRCs perturbs the direction of microtubule growth from the Golgi stacks, consistent with a model for asymmetric microtubule nucleation involving γ-TuRCs and other nucleation-promoting factors. We also directly observe microtubule turning along microtubule bundles and show that depleting APC, proposed to link Kinesin-2 to plus ends, reduces microtubule turning and increases plus end growth into dendrites. These results support a model of asymmetric nucleation and guidance within the neuronal soma that helps establish and maintain overall microtubule polarity.

Rare combination of pulmonary sling and aberrant right subclavian artery with left aortic arch in the same infant

Although rare, vascular sling-ring complexes together in the same patient may be encountered. Once clinical complaints compatible with vascular ring anomalies are described, it should be kept in mind that more than one anomaly may be associated. By this case, the diagnostic and therapeutic course of pulmonary sling (PS) and aberrant right subclavian artery (ARSA) in an infant with breathing and feeding difficulties was presented.

Autoinhibition of Cnn binding to γ-TuRCs prevents ectopic microtubule nucleation and cell division defects

γ-Tubulin ring complexes (γ-TuRCs) nucleate microtubules. They are recruited to centrosomes in dividing cells via binding to N-terminal CM1 domains within γ-TuRC–tethering proteins, including Drosophila Centrosomin (Cnn). Binding promotes microtubule nucleation and is restricted to centrosomes in dividing cells, but the mechanism regulating binding remains unknown. Here, we identify an extreme N-terminal CM1 autoinhibition (CAI) domain found specifically within the centrosomal isoform of Cnn (Cnn-C) that inhibits γ-TuRC binding. Robust binding occurs after removal of the CAI domain or with the addition of phosphomimetic mutations, suggesting that phosphorylation helps relieve inhibition. We show that regulation of Cnn binding to γ-TuRCs is isoform specific and that misregulation of binding can result in ectopic cytosolic microtubules and major defects during cell division. We also find that human CDK5RAP2 is autoinhibited from binding γ-TuRCs, suggesting conservation across species. Overall, our results shed light on how and why CM1 domain binding to γ-TuRCs is regulated.

Pseudorotaxane formation affected by stereo-electronic effects. A theoretical and experimental study

We report a theoretical-experimental study on different complexes of pseudorotaxanes possessing pyridine axes. In order to evaluate the stereo-electronic effect of the methyl substituents in the pyridine ring, complexes with...