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A new biomimetic model complex of the active site of acireductone dioxygenase (ARD) was synthesized and crystallographically characterized ([Ni(II)(N-(ethyl-N′Me 2)(Py)(2-t-ButPhOH))(OTf)]- 1). 1 displays carbon–carbon oxidative cleavage activity in the presence of O2 towards the substrate 2-hydroxyacetophenone. This reactivity was monitored via UV-Visible and NMR spectroscopy. We postulate that the reactivity of 1 with O2 leads to the formation of a putative Ni(III)-superoxo transient species resulting from the direct activation of O2via the nickel center during the oxidative reaction. This proposed intermediate and reaction mechanism were studied in detail using DFT calculations. 1 and its substrate bound derivatives display reactivity toward mild outer sphere oxidants, suggesting ease of access to high valent Ni coordination complexes, consistent with our calculations. If confirmed, the direct activation of O2 at a nickel center could have implications for the mechanism of action of ARD and other nickel-based dioxygenases and their respective non-traditional, enzymatic moonlighting functions, as well as contribute to a general understanding of direct oxidation of nickel(II) coordination complexes by O2. [ABSTRACT FROM AUTHOR]

There is a longstanding interest in whether the loss of complex characters is reversible (so‐called "Dollo's law"). Reevolution has been suggested for numerous traits but among the first was Kurtén, who proposed that the presence of the second lower molar (M2) of the Eurasian lynx (Lynx lynx) was a violation of Dollo's law because all other Felids lack M2. While an early and often cited example for the reevolution of a complex trait, Kurtén and Werdelin used an ad hoc parsimony argument to support their. Here I revisit the evidence that M2 reevolved lynx using explicit parsimony and maximum likelihood models of character evolution and find strong evidence that Kurtén and Werdelin were correct—M2 reevolved in E. lynx. Next, I explore the developmental mechanisms which may explain this violation of Dollo's law and suggest that the reevolution of lost complex traits may arise from the reevolution of cis‐regulatory elements and protein−protein interactions, which have a longer half‐life after silencing that protein coding genes. Finally, I present a developmental model to explain the reevolution M2 in E. lynx, which suggest that the developmental programs required for the establishment of serially homologous characters may never really be lost so long as a single instance of the character remains—thus the gain and loss and regain of serially homologous characters, such mammalian molars, may be developmentally and evolutionarily "simple." Research highlights: There is a growing interest in and renewed debate over whether the loss of complex characters is reversible. Kurtén suggested that the second lower molar (M2) recently reevolved in the Eurasian lynx. A simple model suggest that shared developmental genetic programs make the gain and loss and regain of serially homologous characters, such mammalian molars, evolutionarily "simple." [ABSTRACT FROM AUTHOR]

An enduring problem in biology is explaining how novel functions of genes originated and how those functions diverge between species. Despite detailed studies on the functional evolution of a few proteins, the molecular mechanisms by which protein functions have evolved are almost entirely unknown. Here, we show that a polyalanine tract in the homeodomain transcription factor HoxA11 arose in the stem‐lineage of mammals and functions as an autonomous repressor module by physically interacting with the PAH domains of SIN3 proteins. These results suggest that long polyalanine tracts, which are common in transcription factors and often associated with disease, may tend to function as repressor domains and can contribute to the diversification of transcription factor functions despite the deleterious consequences of polyalanine tract expansion. Research Highlights: A polyalanine track in HoxA11 evolved into a repressor domain through an increase in alanine repeat number, indicating that transcription factors can evolve novel functions despite the potential deleterious consequences associated with amino acid repeats. [ABSTRACT FROM AUTHOR]

The anion binding features of diphenylpyrrole‐strapped calix[4]pyrrole 1 have been investigated by means of 1H NMR spectroscopy and ITC (isothermal titration calorimetry), as well as single crystal X‐ray diffraction analyses. Receptor 1 bearing an auxiliary pyrrolic NH donor and solubilizing phenyl groups on the strap was found to bind F−, Cl−, and Br− as their tetrabutylammonium salts with high affinity in DMSO‐d6. In addition, receptor 1 was found to extract the fluoride anion (as both its tetraethylammonium (TEA+) and tetrabutylammonium (TBA+) salts), as well as the chloride anion into chloroform‐d from an aqueous source phase. Cation metathesis using TBAI or the use of a dual host approach involving crown ethers enabled receptor 1 to extract simple alkali metal fluoride or chloride salts from water. Quantitative binding of NaF by receptor 1 was observed in 20 % D2O‐DMSO‐d6 allowing for the direct determination of the NaF concentration in an unknown sample. [ABSTRACT FROM AUTHOR]

The reaction between Th(IV) dipyriamethyrin dichloride and sodium cyclopentadienyl (Cp) results in the formation of a cyclopentadienyl capped thorium dipyriamethyrin complex, which to our knowledge represents the first expanded porphyrin f-element Cp complex. [ABSTRACT FROM AUTHOR]

A heteroleptic copper(I) bis(phenanthroline) complex with aldehyde groups at the 4,7 positions of the phenanthroline ligand was synthesized. The complex is responsive to alcohol, resulting in a distinct colour change caused by the facile reaction of the aldehyde group with alcohol, forming a hemiacetal product. The aldehyde species can be regenerated after heating the intermediate at 80 °C for 10 minutes, demonstrating the reusability of the complex for alcohol detection. This work presents a new strategy for applying transition metal complexes in small molecule sensing by installing functional groups in the secondary coordination sphere which reversibly react with analytes. [ABSTRACT FROM AUTHOR]

Three new complexes containing 2‐thiophenylterpyridine (TP) ligand, namely, [Co(stpy)2]Cl2 (Co‐TP), [Ni(stpy)Cl2]2 (Ni‐TP) and [Pd(stpy)Cl]Cl (Pd‐TP) were synthesized and subsequently characterized employing various spectroscopic techniques including UV–Visible, IR, 1H NMR, EPR, and ESI‐MS analysis. ESI‐MS spectra suggested the complexes Co‐TP and Ni‐TP to be six coordinated with two ligand units and the complex Pd‐TP to be a four‐coordinated mononuclear square planar complex. The dimeric nature of the complex Ni‐TP (M2L2Cl4) was established by X‐ray diffraction analysis, which confirmed the bridging of two nickel centers by two chloride ions. The ligand and complexes were assessed for their cytotoxic behavior by using MTT colorimetric assay. The compounds TP, Co‐TP, Ni‐TP and Pd‐TP displayed significant antiproliferative activity on A549 (human lung carcinoma) and MM2 (human breast cancer) cell lines and had no toxic effect on human normal embryonic kidney cells (HEK 293). Further, the morphological changes associated with MM2 and A549 cells triggered by the tested compounds due to apoptosis have been validated with the help of AO‐EB and DAPI staining assays. [ABSTRACT FROM AUTHOR]

Embryo implantation in humans is interstitial, meaning the entire conceptus embeds in the endometrium before the placental trophoblast invades beyond the uterine mucosa into the underlying inner myometrium. Once implanted, embryo survival pivots on the transformation of the endometrium into an anti-inflammatory placental bed, termed decidua, under homeostatic control of uterine natural killer cells. Here, we examine the evolutionary context of embryo implantation and elaborate on uterine remodelling before and after conception in humans. We also discuss the interactions between the embryo and the decidualising endometrium that regulate interstitial implantation and determine embryo fitness. Together, this Review highlights the precarious but adaptable nature of the implantation process. [ABSTRACT FROM AUTHOR]

A novel Ru(II) complex containing 4‐(2‐hydroxybenzyl)‐3‐methyl‐5‐oxo‐2,5‐dihydropyrazole‐1‐carbothioic acid methylamide has been applied as a catalyst for directly aminating alcohols. Preliminary investigation on the reaction mechanism has been done with the help of NMR spectroscopy recorded for regenerated catalysts and an NMR reaction. In addition, a plausible mechanism for the formation of the coupled product has been proposed. [ABSTRACT FROM AUTHOR]

Humans are unique in their sophisticated culture and societal structures, their complex languages, and their extensive tool use. According to the human self-domestication hypothesis, this unique set of traits may be the result of an evolutionary process of self-induced domestication, in which humans evolved to be less aggressive and more cooperative. However, the only other species that has been argued to be self-domesticated besides humans so far is bonobos, resulting in a narrow scope for investigating this theory limited to the primate order. Here, we propose an animal model for studying self-domestication: the elephant. First, we support our hypothesis with an extensive cross-species comparison, which suggests that elephants indeed exhibit many of the features associated with self-domestication (e.g., reduced aggression, increased prosociality, extended juvenile period, increased playfulness, socially regulated cortisol levels, and complex vocal behavior). Next, we present genetic evidence to reinforce our proposal, showing that genes positively selected in elephants are enriched in pathways associated with domestication traits and include several candidate genes previously associated with domestication. We also discuss several explanations for what may have triggered a self-domestication process in the elephant lineage. Our findings support the idea that elephants, like humans and bonobos, may be self-domesticated. Since the most recent common ancestor of humans and elephants is likely the most recent common ancestor of all placental mammals, our findings have important implications for convergent evolution beyond the primate taxa, and constitute an important advance toward understanding how and why self-domestication shaped humans' unique cultural niche. [ABSTRACT FROM AUTHOR]

The sensory epithelium of the inner ear, found in all extant lineages of vertebrates, has been subjected to over 500 million years of evolution, resulting in the complex inner ear of modern vertebrates. Inner-ear adaptations are as diverse as the species in which they are found, and such unique anatomical variations have been well studied. However, the evolutionary details of the molecular machinery that is required for hearing are less well known. Two molecules that are essential for hearing in vertebrates are cadherin-23 and protocadherin-15, proteins whose interaction with one another acts as the focal point of force transmission when converting sound waves into electrical signals that the brain can interpret. This "tip-link" interaction exists in every lineage of vertebrates, but little is known about the structure or mechanical properties of these proteins in most non-mammalian lineages. Here, we use various techniques to characterize the evolution of this protein interaction. Results show how evolutionary sequence changes in this complex affect its biophysical properties both in simulations and experiments, with variations in interaction strength and dynamics among extant vertebrate lineages. Evolutionary simulations also characterize how the biophysical properties of the complex in turn constrain its evolution and provide a possible explanation for the increase in deafness-causing mutants observed in cadherin-23 relative to protocadherin-15. Together, these results suggest a general picture of tip-link evolution in which selection acted to modify the tip-link interface, although subsequent neutral evolution combined with varying degrees of purifying selection drove additional diversification in modern tetrapods. [ABSTRACT FROM AUTHOR]