Regulatory and coding sequences of TRNP1 co-evolve with brain size and cortical folding in mammals

Brain size and cortical folding have increased and decreased recurrently during mammalian evolution. Identifying genetic elements whose sequence or functional properties co-evolve with these traits can provide unique information on evolutionary and developmental mechanisms. A good candidate for such a comparative approach is TRNP1, as it controls proliferation of neural progenitors in mice and ferrets. Here, we investigate the contribution of both regulatory and coding sequences of TRNP1 to brain size and cortical folding in over 30 mammals. We find that the rate of TRNP1 protein evolution (omega) significantly correlates with brain size, slightly less with cortical folding and much less with body size. This brain correlation is stronger than for >95% of random control proteins. This co-evolution is likely affecting TRNP1 activity, as we find that TRNP1 from species with larger brains and more cortical folding induce higher proliferation rates in neural stem cells. Furthermore, we compare the activity of putative cis-regulatory elements (CREs) of TRNP1 in a massively parallel reporter assay and identify one CRE that likely co-evolves with cortical folding in Old World monkeys and apes. Our analyses indicate that coding and regulatory changes that increased TRNP1 activity were positively selected either as a cause or a consequence of increases in brain size and cortical folding. They also provide an example how phylogenetic approaches can inform biological mechanisms, especially when combined with molecular phenotypes across several species

Pulsed triple electron resonance (TRIER) for dipolar correlation spectroscopy

Pribitzer S, Sajid M, Huelsmann M, Godt A, Jeschke G. Pulsed triple electron resonance (TRIER) for dipolar correlation spectroscopy. JOURNAL OF MAGNETIC RESONANCE. 2017;282:119-128.A new pulse sequence is presented for correlating dipolar frequencies in molecules with more than two paramagnetic centers. This triple electron resonance experiment (TRIER) is an extension the double electron-electron resonance (DEER) experiment, which is widely used for distance determination in the nanometer range. We use linear chirp pulses with smoothed edges to create a refocused observer echo, and two hyperbolic secant pulses with distinct excitation windows to excite two other subsets of spins. These pumped spins are coupled to the observed spin through the dipole-dipole interaction. A two-dimensional dipolar modulation pattern is recorded by variation of the position of the two pump pulses. By two-dimensional Fourier transform of the echo integral, a plot is obtained that correlates dipolar frequencies within the same molecule. Such correlation patterns can be used in conjunction with DEER, with which distance distributions are usually determined for several doubly labeled molecules with different spin-labeling sites. In the presence of two conformers, DEER traces give two distances and assignment to an individual conformer is not trivial and usually requires a trial and error approach. TRIER can potentially provide the missing connection between distances as correlations between dipolar frequencies. (C) 2017 Elsevier Inc. All rights reserved

Postsynthetic Modification of Metal-Organic Frameworks through Nitrile Oxide-Alkyne Cycloaddition

von Zons T, Brokmann L, Lippke J, et al. Postsynthetic Modification of Metal-Organic Frameworks through Nitrile Oxide-Alkyne Cycloaddition. INORGANIC CHEMISTRY. 2018;57(6):3348-3359.Postsynthetic modification of metal-organic frameworks is an important method to tailor their properties. We report on the nitrile oxide-alkyne cycloaddition (NOAC) as a modification tool, a reaction requiring neither strained alkynes nor a catalyst. This is demonstrated with the reaction of nitrile oxides with PEPEP-PIZOF-15 and-19 at room temperature. PIZOF-15 and-19 are porous Zr-based MOFs (BET surface areas 1740 and 960 m(2) g(-1), respectively) consisting of two mutually interpenetrating UiO-type frameworks with linkers of the type -O2C[PE-P(R-1,R-2)-EP]CO2- (P, phenylene; E, ethynylene; and R-2, side chains at the central benzene ring with R-1 = R-2 = OCH2C CH or R-1 = OCH2C CH and R-2 = O(CH2CH2O)(3)Me). Their syntheses, using benzoic acid as a modulator, and their characterization are reported herein. The propargyloxy (OCH2C CH) side chains contain the ethyne moieties needed for NOAC. Formation of nitrile oxides through oxidation of oximes in aqueous ethanolic solution in the presence of PEPEP-PIZOF-15 and -19 resulted in the reaction of 96-100% of the ethyne moieties to give isoxazoles. Thereby the framework was preserved. The type of nitrile oxide RCNO was greatly varied with R being isopentyl, tolyl, 2-pyridyl, and pentafluorophenyl. A detailed NMR spectroscopic investigation showed the formation of the 3,5-disubstituted isoxazole to be clearly favored (>96%) over that of the constitutional isomeric 3,4-disubstituted isoxazole, except for one example