There has been a considerable increase in studies investigating rates of diversification and character evolution, with one of the promising techniques being the BiSSE method (binary state speciation ...and extinction). This study uses simulations under a variety of different sample sizes (number of tips) and asymmetries of rate (speciation, extinction, character change) to determine BiSSE's ability to test hypotheses, and investigate whether the method is susceptible to confounding effects.
We found that the power of the BiSSE method is severely affected by both sample size and high tip ratio bias (one character state dominates among observed tips). Sample size and high tip ratio bias also reduced accuracy and precision of parameter estimation, and resulted in the inability to infer which rate asymmetry caused the excess of a character state. In low tip ratio bias scenarios with appropriate tip sample size, BiSSE accurately estimated the rate asymmetry causing character state excess, avoiding the issue of confounding effects.
Based on our findings, we recommend that future studies utilizing BiSSE that have fewer than 300 terminals and/or have datasets where high tip ratio bias is observed (i.e., fewer than 10% of species are of one character state) should be extremely cautious with the interpretation of hypothesis testing results.
Bioluminescence is primarily a marine phenomenon with 80% of metazoan bioluminescent genera occurring in the world's oceans. Here we show that bioluminescence has evolved repeatedly and is ...phylogenetically widespread across ray-finned fishes. We recover 27 independent evolutionary events of bioluminescence, all among marine fish lineages. This finding indicates that bioluminescence has evolved many more times than previously hypothesized across fishes and the tree of life. Our exploration of the macroevolutionary patterns of bioluminescent lineages indicates that the present day diversity of some inshore and deep-sea bioluminescent fish lineages that use bioluminescence for communication, feeding, and reproduction exhibit exceptional species richness given clade age. We show that exceptional species richness occurs particularly in deep-sea fishes with intrinsic bioluminescent systems and both shallow water and deep-sea lineages with luminescent systems used for communication.
The past decade has seen a dramatic increase in scholarly interest in the topic of authentic leadership. We review this literature with the goal of clarifying the state of knowledge in the field. We ...begin with a historical overview of the construct's definition and evolution. Next, we present the results of a content analysis of 91 publications that focus on authentic leadership. Specifically, we examined the publication type (theoretical, empirical, and practitioner), contributors (e.g., discipline, nationality, and institutional affiliation), theoretical foundations, research strategies, sample location/type, data collection methods, analytical procedures, and nomological network of authentic leadership. We conclude by presenting an agenda for future research.
Binding carbohydrates from water is a difficult task, even for the natural carbohydrate-binding proteins known as lectins. The design of synthetic lectin mimics is correspondingly challenging, ...especially if good selectivities are required. In previous work we showed that success is possible, but only for complex polycyclic architectures that require lengthy and low-yielding syntheses; for example, one glucose-selective system was made in 21 steps and only 0.1% overall yield. Here we report the discovery of a simple monocyclic host that matches the earlier designs, but is far more accessible as it is prepared in just five steps and 23% overall yield. The new synthetic lectin binds glucose with excellent selectivity versus other common monosaccharides (for example, ~50:1 versus galactose) and sufficient affinity for glucose sensing at the concentrations found in blood. It also features a built-in signalling system in the form of strong and guest-dependent fluorescence emission. The effectiveness and simplicity of this molecule suggests the potential for development into a new methodology for practical glucose monitoring.
Ray-finned fishes make up half of all living vertebrate species. Nearly all ray-finned fishes are teleosts, which include most commercially important fish species, several model organisms for ...genomics and developmental biology, and the dominant component of marine and freshwater vertebrate faunas. Despite the economic and scientific importance of ray-finned fishes, the lack of a single comprehensive phylogeny with corresponding divergence-time estimates has limited our understanding of the evolution and diversification of this radiation. Our analyses, which use multiple nuclear gene sequences in conjunction with 36 fossil age constraints, result in a well-supported phylogeny of all major rayfinned fish lineages and molecular age estimates that are generally consistent with the fossil record. This phylogeny informs three longstanding problems: specifically identifying elopomorphs (eels and tarpons) as the sister lineage of all other teleosts, providing a unique hypothesis on the radiation of early euteleosts, and offering a promising strategy for resolution of the "bush at the top of the tree" that includes percomorphs and other spiny-finned teleosts. Contrasting our divergence time estimates with studies using a single nuclear gene or whole mitochondrial genomes, we find that the former underestimates ages of the oldest ray-finned fish divergences, but the latter dramatically overestimates ages for derived teleost lineages. Our time-calibrated phylogeny reveals that much of the diversification leading to extant groups of teleosts occurred between the late Mesozoic and early Cenozoic, identifying this period as the "Second Age of Fishes."
New sequencing technologies pose significant challenges in terms of data complexity and magnitude. It is essential that efficient software is developed with performance that scales with this growth ...in sequence information. Here we present a comprehensive and integrated set of tools for the analysis of data from large scale sequencing experiments. It supports adapter detection and removal, demultiplexing of barcodes, paired-end data, a range of read architectures and the efficient removal of sequence redundancy. Sequences can be trimmed and filtered based on length, quality and complexity. Quality control plots track sequence length, composition and summary statistics with respect to genomic annotation. Several use cases have been integrated into a single streamlined pipeline, including both mRNA and small RNA sequencing experiments. This pipeline interfaces with existing tools for genomic mapping and differential expression analysis.
A biomimetic receptor for glucose Tromans, Robert A; Carter, Tom S; Chabanne, Laurent ...
Nature chemistry,
01/2019, Letnik:
11, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Specific molecular recognition is routine for biology, but has proved difficult to achieve in synthetic systems. Carbohydrate substrates are especially challenging, because of their diversity and ...similarity to water, the biological solvent. Here we report a synthetic receptor for glucose, which is biomimetic in both design and capabilities. The core structure is simple and symmetrical, yet provides a cavity which almost perfectly complements the all-equatorial β-pyranoside substrate. The receptor's affinity for glucose, at K
~ 18,000 M
, compares well with natural receptor systems. Selectivities also reach biological levels. Most other saccharides are bound approximately 100 times more weakly, while non-carbohydrate substrates are ignored. Glucose-binding molecules are required for initiatives in diabetes treatment, such as continuous glucose monitoring and glucose-responsive insulin. The performance and tunability of this system augur well for such applications.
Carbohydrate recognition is biologically important but intrinsically challenging, for both nature and host-guest chemists. Saccharides are complex, subtly variable, and camouflaged by hydroxyl groups ...that hinder discrimination between substrate and water. We have developed a rational strategy for the biomimetic recognition of carbohydrates with all-equatorial stereochemistry (β-glucose, analogs, and homologs) and have now applied it to disaccharides such as cellobiose. Our synthetic receptor showed good affinities, not unlike those of some lectins (carbohydrate-binding proteins). Binding was demonstrated by nuclear magnetic resonance, induced circular dichroism, fluorescence spectroscopy, and calorimetry, all methods giving self-consistent results. Selectivity for the target substrates was exceptional; minor changes to disaccharide structure (for instance, cellobiose to lactose) caused almost complete suppression of complex formation.
The discovery of fluorescent proteins has revolutionized experimental biology. Whereas the majority of fluorescent proteins have been identified from cnidarians, recently several fluorescent proteins ...have been isolated across the animal tree of life. Here we show that biofluorescence is not only phylogenetically widespread, but is also phenotypically variable across both cartilaginous and bony fishes, highlighting its evolutionary history and the possibility for discovery of numerous novel fluorescent proteins. Fish biofluorescence is especially common and morphologically variable in cryptically patterned coral-reef lineages. We identified 16 orders, 50 families, 105 genera, and more than 180 species of biofluorescent fishes. We have also reconstructed our current understanding of the phylogenetic distribution of biofluorescence for ray-finned fishes. The presence of yellow long-pass intraocular filters in many biofluorescent fish lineages and the substantive color vision capabilities of coral-reef fishes suggest that they are capable of detecting fluoresced light. We present species-specific emission patterns among closely related species, indicating that biofluorescence potentially functions in intraspecific communication and evidence that fluorescence can be used for camouflage. This research provides insight into the distribution, evolution, and phenotypic variability of biofluorescence in marine lineages and examines the role this variation may play.
Diabetes mellitus is a major risk factor for peripheral arterial disease and lower extremity amputation (LEA). We evaluated the effects of intensive glucose control (IGC) on risk of LEA in patients ...with type 2 diabetes during a randomized-controlled multicenter trial.
The Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial randomized patients with type 2 diabetes to IGC (HbA1c target < 6.0%) or standard glycemic control (SGC; HbA1c target 7.0% to 7.9%). Using analysis of mean HbA1c, we examined relationships between glycemic control and incident/recurrent LEA during the clinical trial/follow-up.
Mean post-randomization HbA1c over the course of the trial and post-trial follow-up was 7.3% ± 0.9% (6.8% ± 0.8% in the IGC arm, 7.7% ± 0.7% in the SGC arm). There were 124 participants who had at least 1 LEA during the study period; 73 were randomized to the SGC arm and 51 to the IGC arm (p = 0.049). Randomization to IGC was associated with decreased LEA rate (HR 0.69, 95% CI 0.483 to 0.987, p = 0.042). In multivariable models, mean HbA1c was a powerful predictor of LEA (HR 2.07 per 1% increase in HbA1c, 95% CI 1.67 to 2.57, p < 0.0001). Post-randomization mean HbA1c remained a strong predictor of LEA after controlling for other important covariates and competing risk of death (HR 1.94 per 1% increase in HbA1c, 95% CI 1.52 to 2.46, p < 0.0001).
In patients with type 2 diabetes, IGC was associated with a reduction in the risk for LEA. After 3.7 years of IGC, there was an enduring protective effect against LEA. Improved glycemic control was a strong predictor of decreased risk for subsequent LEA. This study suggests that tight glycemic control, even over a short time period, has potential to reduce risk of limb loss.
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