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SUMMARY: The anther‐enriched phased, small interfering RNAs (phasiRNAs) play vital roles in sustaining male fertility in grass species. Their long non‐coding precursors are synthesized by RNA polymerase II and are likely regulated by transcription factors (TFs). A few putative transcriptional regulators of the 21‐ or 24‐nucleotide phasiRNA loci (referred to as 21‐ or 24‐PHAS loci) have been identified in maize (Zea mays), but whether any of the individual TFs or TF combinations suffice to activate any PHAS locus is unclear. Here, we identified the temporal gene coexpression networks (modules) associated with maize anther development, including two modules highly enriched for the 21‐ or 24‐PHAS loci. Comparisons of these coexpression modules and gene sets dysregulated in several reported male sterile TF mutants provided insights into TF timing with regard to phasiRNA biogenesis, including antagonistic roles for OUTER CELL LAYER4 and MALE STERILE23. Trans‐activation assays in maize protoplasts of individual TFs using bulk‐protoplast RNA‐sequencing showed that two of the TFs coexpressed with 21‐PHAS loci could activate several 21‐nucleotide phasiRNA pathway genes but not transcription of 21‐PHAS loci. Screens for combinatorial activities of these TFs and, separately, the recently reported putative transcriptional regulators of 24‐PHAS loci using single‐cell (protoplast) RNA‐sequencing, did not detect reproducible activation of either 21‐PHAS or 24‐PHAS loci. Collectively, our results suggest that the endogenous transcriptional machineries and/or chromatin states in the anthers are necessary to activate reproductive PHAS loci. Significance Statement: This work identifies the temporal gene coexpression networks associated with maize anther development, including two modules highly enriched for the 21‐ or 24‐nucleotide reproductive phased, small interfering RNA (phasiRNA) loci. Trans‐activation assays of putative transcriptional regulators of the phasiRNA loci using bulk and single‐cell RNA‐sequencing suggest that endogenous transcriptional machineries and/or chromatin states in the anthers are necessary to activate reproductive phasiRNA loci. [ABSTRACT FROM AUTHOR]

Anthers express the most genes of any plant organ, and their development involves sequential redifferentiation of many cell types to perform distinctive roles from inception through pollen dispersal. Agricultural yield and plant breeding depend on understanding and consequently manipulating anthers, a compelling motivation for basic plant biology research to contribute. After stamen initiation, two theca form at the tip, and each forms an adaxial and abaxial lobe composed of pluripotent Layer 1-derived and Layer 2-derived cells. After signal perception or self-organization, germinal cells are specified from Layer 2-derived cells, and these secrete a protein ligand that triggers somatic differentiation of their neighbors. Historically, recovery of male-sterile mutants has been the starting point for studying anther biology. Many genes and some genetic pathways have well-defined functions in orchestrating subsequent cell fate and differentiation events. Today, new tools are providing more detailed information; for example, the developmental trajectory of germinal cells illustrates the power of single cell RNA-seq to dissect the complex journey of one cell type. We highlight ambiguities and gaps in available data to encourage attention on important unresolved issues. [ABSTRACT FROM AUTHOR]

Running is a popular and convenient form of leisure-time physical activity, with participation levels increasing in the United Kingdom in low physical activity groups such as women and overweight individuals, following the introduction of schemes such as Couch to 5km (C25 K). However, despite the popularity of these programmes, there is little research into the social and psychological processes involved in effective engagement and long-term behaviour changes. Therefore, the aim of the study was to explore the impact of participation in a 10-week group-led beginners running programme on participant motivation, attendance and well-being using Self-Determination Theory (STD) as a theoretical framework. Participants (N = 124; Mage = 40.74) were recruited from a beginners' running programme based in the North West of England and self-completed questionnaires during weeks 2, 6 and 10. Future intentions to run were also assessed at 3- and 6-month follow up. Results demonstrated the positive impact an adapted C25 K model can have upon elements of self-perceptions (particularly perceived competence) and future intentions to run. The path analysis, which looked at average values over time, demonstrated that leader autonomy support positively impacted upon participants' basic needs satisfaction, which led to the development of more self-determined motivation, and in turn led to higher levels of attendance and mental well-being. Critically for drop-out, results from multiple regression analysis indicated that individuals with a higher BMI rated leader autonomy support as lower and felt less competent during the programme. A number of research and practical recommendations are discussed. [ABSTRACT FROM AUTHOR]

An external focus of attention, enhanced expectancies and autonomy support are key independent and interactive characteristics which enhance motor learning. These OPTIMAL (Optimizing Performance Through Intrinsic Motivation and Attention for Learning) characteristics have proven supportive of adult's motor learning yet, their effect on children's motor learning is comparatively under-explored. Fifty-five studies were systematically reviewed to outline the impact of OPTIMAL variables on children's motor learning, specifically foundational movement skills (FMS). Thirty-five studies examined an external focus of attention, whereas relatively few addressed enhanced expectancies (n = 12) and autonomy support (n = 8). Only 2 explored the interaction between OPTIMAL variables. Results show emerging evidence that OPTIMAL variables contribute to children's effective motor learning. Despite this initial support, there is a paucity of research regarding the impact of OPTIMAL variables across the full FMS range (i.e. a skewness towards object manipulation skills). Moreover, children's different developmental characteristics may moderate the beneficial effects of OPTIMAL variables. Additionally, the attentional and motivational mechanisms underpinning OPTIMAL learning (e.g. self-efficacy) in children requires future work. Finally, there is a need for future combinatory research addressing OPTIMAL variables in children (e.g. enhanced expectancies with autonomy support). The theoretical and practical implications of the findings are discussed throughout. [ABSTRACT FROM AUTHOR]

Summary: Ferns appear in the fossil record some 200 Myr before angiosperms. However, as angiosperm‐dominated forest canopies emerged in the Cretaceous period there was an explosive diversification of modern (leptosporangiate) ferns, which thrived in low, blue‐enhanced light beneath angiosperm canopies. A mechanistic explanation for this transformative event in the diversification of ferns has remained elusive.We used physiological assays, transcriptome analysis and evolutionary bioinformatics to investigate a potential connection between the evolution of enhanced stomatal sensitivity to blue light in modern ferns and the rise of angiosperm‐dominated forests in the geological record.We demonstrate that members of the largest subclade of leptosporangiate ferns, Polypodiales, have significantly faster stomatal response to blue light than more ancient fern lineages and a representative angiosperm. We link this higher sensitivity to levels of differentially expressed genes in blue‐light signaling, particularly in the cryptochrome (CRY) signaling pathway. Moreover, CRYs of the Polypodiales examined show gene duplication events between 212.9–196.9 and 164.4–151.8 Ma, when angiosperms were emerging, which are lacking in other major clades of extant land plants.These findings suggest that evolution of stomatal blue‐light sensitivity helped modern ferns exploit the shady habitat beneath angiosperm forest canopies, fueling their Cretaceous hyperdiversification. See also the Commentary on this article by Chater, 230: 886–888. [ABSTRACT FROM AUTHOR]

Chloroplast retrograde signaling networks are vital for chloroplast biogenesis, operation, and signaling, including excess light and drought stress signaling. To date, retrograde signaling has been considered in the context of land plant adaptation, but not regarding the origin and evolution of signaling cascades linking chloroplast function to stomatal regulation. We show that key elements of the chloroplast retrograde signaling process, the nucleotide phosphatase (SAL1) and 3'-phosphoadenosine-5'-phosphate (PAP) metabolism, evolved in streptophyte algae--the algal ancestors of land plants. We discover an early evolution of SAL1-PAP chloroplast retrograde signaling in stomatal regulation based on conserved gene and protein structure, function, and enzyme activity and transit peptides of SAL1s in species including flowering plants, the fern Ceratopteris richardii, and the moss Physcomitrella patens. Moreover, we demonstrate that PAP regulates stomatal closure via secondary messengers and ion transport in guard cells of these diverse lineages. The origin of stomata facilitated gas exchange in the earliest land plants. Our findings suggest that the conquest of land by plants was enabled by rapid response to drought stress through the deployment of an ancestral SAL1-PAP signaling pathway, intersecting with the core abscisic acid signaling in stomatal guard cells. [ABSTRACT FROM AUTHOR]

A number of companies are marketing general eye–hand coordination training devices, which are purported to enhance performance on the device and in a sporting domain. An act comprising eye–hand coordination involves the complex combination of a number of distinct functions, and an investigation of what tasks share this common factor has not been completed. There is also a lack of evidence investigating the interrelationship between different tests to assess eye–hand coordination using these devices. A number of different eye–hand coordination abilities, rather than one common factor, could potentially underpin any range of tasks involving eye–hand coordination and visual stimuli. Therefore, the present study investigated the theoretical assumption upon which such eye–hand coordination training devices are based, that is, whether eye–hand coordination is a general ability. Eighty-seven currently active sportspeople (age: 18.6 ± 0.9 years; 58 males and 29 females) completed four tests of eye–hand coordination: three laboratory tasks (the Sports Vision Trainer™; Batak Pro™; and Graded Pegboard) and a field task (wall catch test). Intercorrelations between the tasks ranged from weak to strong, but the percentage of shared variance was typically low. Overall, the results do not support the existence of a common eye–hand coordination ability underpinning the performance on general eye–hand coordination training devices. Consequently, coaches and sport scientists should be aware that training on general eye–hand coordination training devices is unlikely to transfer to sporting performances. Instead, practitioners are encouraged to explore sport-specific assessment and training of eye–hand coordination. [ABSTRACT FROM AUTHOR]

Polyploidy has extensive genetic, physiological, morphological, and ecological ramifications. While the patterns underlying the genetic and morphological consequences of polyploidy are being rapidly elucidated, the effects on ecological niche are still largely unknown., This study investigated 13 allopolyploid systems in North America (10 ferns and three angiosperms) using digitized natural history museum specimens. The abiotic niches of the allopolyploids were compared with those of their diploid progenitors using ecological niche modeling, niche analyses, and multivariate analyses., We identified four patterns of niche shifts through our analyses: niche expansion, niche contraction, niche intermediacy, and niche novelty. The classification of these shifts depended on the amount of niche overlap and breadth between the polyploid and progenitors. The most common niche shift was niche intermediacy in which the polyploid inhabited a geographic range between that of the progenitors and had a high degree of niche overlap., Each polyploid had at least partial geographic sympatry and abiotic niche overlap with one of its progenitors, suggesting that biotic and/or microclimate factors may play a larger role in polyploid establishment than previously hypothesized. This study provides a baseline for future comparisons of the diverse outcomes of genome merger and duplication on abiotic niche preference. [ABSTRACT FROM AUTHOR]

Plant genomes vary in size and complexity, fueled in part by processes of whole-genome duplication (WGD; polyploidy) and subsequent genome evolution. Despite repeated episodes of WGD throughout the evolutionary history of angiosperms in particular, the genomes are not uniformly large, and even plants with very small genomes carry the signatures of ancient duplication events. The processes governing the evolution of plant genomes following these ancient events are largely unknown. Here, we consider mechanisms of diploidization, evidence of genome reorganization in recently formed polyploid species, and macroevolutionary patterns of WGD in plant genomes and propose that the ongoing genomic changes observed in recent polyploids may illustrate the diploidization processes that result in ancient signatures of WGD over geological timescales. [ABSTRACT FROM AUTHOR]

We present a glacial record from the western Olympus Range, East Antarctica, that documents a permanent shift in the thermal regime of local glaciers, from wet- to cold-based regimes, more than 13.94 m.y. ago. This glacial record provides the first terrestrial evidence linking middle Miocene global climate cooling to a permanent reorganization of the Antarctic cryosphere and to subsequent growth of the polar East Antarctic Ice Sheet. The composite stratigraphic record constructed from field mapping and analyses of 281 soil excavations shows a classic wet-based till (Circe till, including an extensive melt-out facies), overlain by a weathered colluvial deposit (Electra colluvium), and then a series of stacked tills deposited from cold-based ice (Dido drift). Chronologic control comes from 40Ar/39Ar analyses of concentrated ash-fall deposits interbedded within glacial deposits. The shift from wet- to cold-based glaciation reflects a drop in mean annual temperature of 25–30 °C and is shown to precede one or more major episodes of ice-sheet expansion across the region, the youngest of which occurred between 13.62 and 12.44 Ma. One implication is that atmospheric cooling, following a relatively warm mid-Miocene climatic optimum ca. 17 to 15 Ma, may have led to, and thus triggered, maximum ice-sheet overriding. [ABSTRACT FROM AUTHOR]

The article assesses the effects of silicon (Si) content on the behavior of the resultant composite. The researchers found that reduction in Si content led to significant increases in hardness and Young's modulus, nearly matching results seen with hot pressed boron carbide (B4C). They concluded that the properties of reaction bonded ceramics differ from those of traditional hot pressed and sintered ceramics due to the presence of a Si second phase.

The article presents a study on the effects of silicon:silicon carbide (Si:SiC) ratio and SiC grain size on properties of reaction bonded silicon carbide (RBSC). The study was able to conclude that compared to other physical properties, the grain size had a great effect on the flexural strength of the composite. Increasing the carbon content which resulted to decreased residual Si in the composite had a stronger influence on the modulus than on the density. Data are included to describe the parameters used in this experiment.