Brønsted Acid-Catalyzed, Asymmetric Allenoate Claisen Reaction.

An auxiliary-based protocol is described for an asymmetric allenoate Claisen rearrangement. Silicated tosic acid (10 mol %) was used as an inexpensive, user-friendly catalyst. Stereochemical analysis revealed a preferential attack at the face of prostereogenic olefin.

Female meiotic drive in plants: mechanisms and dynamics.

Female meiosis is fundamentally asymmetric, creating an arena for genetic elements to compete for inclusion in the egg to maximize their transmission. Centromeres, as mediators of chromosomal segregation, are prime candidates to evolve via 'female meiotic drive'. According to the centromere-drive model, the asymmetry of female meiosis ignites a coevolutionary arms race between selfish centromeres and kinetochore proteins, the by-product of which is accelerated sequence divergence.

Building Radical Listening and Empathy through an Implementation Lab in an Undergraduate Microbiology Course.

With rapid advances in science and technology, individuals are faced with the challenging process of making decisions based on sound and accurate information. As a result, to promote scientific literacy, scientists must be able to engage with a wide range of audiences in an inclusive and engaging manner. In addition to a solid knowledge of facts and data, effective scientific communication requires an empathetic approach that comes from a place of understanding and values the knowledge and experience of the intended audience.

Corrigendum: Neural mechanisms for turn-taking in duetting plain-tailed wrens.

[This corrects the article DOI: 10.3389/fncir.2022.

Neural mechanisms for turn-taking in duetting plain-tailed wrens.

Recent studies conducted in the natural habitats of songbirds have provided new insights into the neural mechanisms of turn-taking. For example, female and male plain-tailed wrens () sing a duet that is so precisely timed it sounds as if a single bird is singing. In this review, we discuss our studies examining the sensory and motor cues that pairs of wrens use to coordinate the rapid alternation of syllable production.

Supergene potential of a selfish centromere.

Selfishly evolving centromeres bias their transmission by exploiting the asymmetry of female meiosis and preferentially segregating to the egg. Such female meiotic drive systems have the potential to be supergenes, with multiple linked loci contributing to drive costs or enhancement. Here, we explore the supergene potential of a selfish centromere () in , which was discovered in the Iron Mountain (IM) Oregon population.

Early giant reveals faster evolution of large body size in ichthyosaurs than in cetaceans.

Body sizes of marine amniotes span six orders of magnitude, yet the factors that governed the evolution of this diversity are largely unknown. High primary production of modern oceans is considered a prerequisite for the emergence of cetacean giants, but that condition cannot explain gigantism in Triassic ichthyosaurs. We describe the new giant ichthyosaur sp.

Basal ganglia: Bursting with song.

The songs of mature zebra finches are notoriously repetitious, or 'crystallized'. Despite this stability, new work reveals that chronic pharmacologically driven bursting of cortical inputs to the basal ganglia can drive cumulative and lasting changes to multiple vocal features, including phenomena reminiscent of human stuttering.

Evolution of vision and hearing modalities in theropod dinosaurs.

Owls and nightbirds are nocturnal hunters of active prey that combine visual and hearing adaptations to overcome limits on sensory performance in low light. Such sensory innovations are unknown in nonavialan theropod dinosaurs and are poorly characterized on the line that leads to birds. We investigate morphofunctional proxies of vision and hearing in living and extinct theropods and demonstrate deep evolutionary divergences of sensory modalities.

Selfish chromosomal drive shapes recent centromeric histone evolution in monkeyflowers.

Centromeres are essential mediators of chromosomal segregation, but both centromeric DNA sequences and associated kinetochore proteins are paradoxically diverse across species. The selfish centromere model explains rapid evolution by both components via an arms-race scenario: centromeric DNA variants drive by distorting chromosomal transmission in female meiosis and attendant fitness costs select on interacting proteins to restore Mendelian inheritance. Although it is clear than centromeres can drive and that drive often carries costs, female meiotic drive has not been directly linked to selection on kinetochore proteins in any natural system.

Silver-Catalyzed, -Formylation of Amines Using Glycol Ethers.

A silver-catalyzed protocol was found to afford the -formylation of amines in moderate-to-good yields. Ethylene glycol-derived, oligomeric ethers were found to function as the formylating agent, with 1,4-dioxane affording the best results. This reaction does not require the use of stoichiometric activating reagents, and avoids the use of explosive reagents or toxic gases, such as CO, as the C1 synthon.

Retraction Note: Hummingbird-sized dinosaur from the Cretaceous period of Myanmar.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Ontogeny and potential function of poacher armor (Actinopterygii: Agonidae).

Many vertebrates are armored over all or part of their body. The armor may serve several functional roles including defense, offense, visual display, and signal of experience/capability. Different roles imply different tradeoffs; for example, defensive armor usually trades resistance to attack for maneuverability.

Hummingbird-sized dinosaur from the Cretaceous period of Myanmar.

Skeletal inclusions in approximately 99-million-year-old amber from northern Myanmar provide unprecedented insights into the soft tissue and skeletal anatomy of minute fauna, which are not typically preserved in other depositional environments. Among a diversity of vertebrates, seven specimens that preserve the skeletal remains of enantiornithine birds have previously been described, all of which (including at least one seemingly mature specimen) are smaller than specimens recovered from lithic materials. Here we describe an exceptionally well-preserved and diminutive bird-like skull that documents a new species, which we name Oculudentavis khaungraae gen.

Prediction and Dissipation in Nonequilibrium Molecular Sensors: Conditionally Markovian Channels Driven by Memoryful Environments.

Biological sensors must often predict their input while operating under metabolic constraints. However, determining whether or not a particular sensor is evolved or designed to be accurate and efficient is challenging. This arises partly from the functional constraints being at cross purposes and partly since quantifying the prediction performance of even in silico sensors can require prohibitively long simulations, especially when highly complex environments drive sensors out of equilibrium.

A Hierarchical View of Gecko Locomotion: Photic Environment, Physiological Optics, and Locomotor Performance.

Terrestrial animals move in complex habitats that vary over space and time. The characteristics of these habitats are not only defined by the physical environment, but also by the photic environment, even though the latter has largely been overlooked. For example, numerous studies of have examined the role of habitat structure, such as incline, perch diameter, and compliance, on running performance.

Patterns of Bird-Bacteria Associations.

Birds, with their broad geographic ranges and close association with humans, have historically played an important role as carriers of human disease and as reservoirs for drug-resistant bacteria. Here, we examine scientific literature over a 15-year timespan to identify reported avian-bacterial associations and factors that may impact zoonotic disease emergence by classifying traits of bird species and their bacteria. We find that the majority of wild birds studied were migratory, in temperate habitats, and in the order Passeriformes.

Eyes Wide Shut: the impact of dim-light vision on neural investment in marine teleosts.

Understanding how organismal design evolves in response to environmental challenges is a central goal of evolutionary biology. In particular, assessing the extent to which environmental requirements drive general design features among distantly related groups is a major research question. The visual system is a critical sensory apparatus that evolves in response to changing light regimes.

Non-uniform evolutionary response of gecko eye size to changes in diel activity patterns.

Geckos feature a large range of eye sizes, but what drives this phenotypic diversity is currently unknown. Earlier studies point towards diel activity patterns (DAPs) and locomotory mode, but phylogenetic comparative studies in support of the proposed adaptive mode of eye evolution are lacking. Here, we test the hypothesis of DAPs as the driver of eye size evolution with a dataset on 99 species of gecko.

Predicting Indirect Effects of Predator-Prey Interactions.

Predicting the effects of climate change on species and communities remains a pre-eminent challenge for biologists. Critical among this is understanding the indirect effects of climate change, which arise when the direct, physiological effects of climate on one species change the outcome of its interaction with a second species, altering the success of the second species. A diverse array of approaches to predicting indirect effects exists from mechanistic models, which attempt to build-up from physiological changes to ecological consequences, to ecological models that focus solely on the ecological scale.

Matching 4.7-Å XRD spacing in amelogenin nanoribbons and enamel matrix.

The recent discovery of conditions that induce nanoribbon structures of amelogenin protein in vitro raises questions about their role in enamel formation. Nanoribbons of recombinant human full-length amelogenin (rH174) are about 17 nm wide and self-align into parallel bundles; thus, they could act as templates for crystallization of nanofibrous apatite comprising dental enamel. Here we analyzed the secondary structures of nanoribbon amelogenin by x-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) and tested if the structural motif matches previous data on the organic matrix of enamel.

Male killing Spiroplasma preferentially disrupts neural development in the Drosophila melanogaster embryo.

Male killing bacteria such as Spiroplasma are widespread pathogens of numerous arthropods including Drosophila melanogaster. These maternally transmitted bacteria can bias host sex ratios toward the female sex in order to 'selfishly' enhance bacterial transmission. However, little is known about the specific means by which these pathogens disrupt host development in order to kill males.

Dynamic instability-driven centering/segregating mechanism in bacteria.

All cells require the ability to process spatial information to properly position intracellular molecules. Many protein complexes and DNA molecules are actively positioned either at the cell midpoint or cell poles, but the processes which drive intracellular positioning are still poorly understood. Using computational modeling we propose a bimodal centering/segregation mechanism in bacteria which is driven by the dynamic instability of polymerizing filaments, which grow and shrink with regularity.

Investigations of CHD1 function in transcription and development of Drosophila melanogaster.

In this report we describe chd1 mutant alleles and show that the CHD1 chromatin-remodeling factor is important for wing development and fertility. While CHD1 colocalizes with elongating RNA polymerase II (Pol II) on polytene chromosomes, elongating Pol II can persist on chromatin in the absence of CHD1. These results clarify the roles of chromatin remodelers in transcription and provide novel insights into CHD1 function.