Developmental evolution of flowering plant pollen tube cell walls: callose synthase (CalS) gene expression patterns

<p>Abstract</p> <p>Background</p> <p>A number of innovations underlie the origin of rapid reproductive cycles in angiosperms. A critical early step involved the modification of an ancestrally short and slow-growing pollen tube for faster and longer distance transport of sperm to egg. Associated with this shift are the predominantly callose (1,3-β-glucan) walls and septae (callose plugs) of angiosperm pollen tubes. Callose synthesis is mediated by callose synthase (CalS). Of 12 <it>CalS </it>gene family members in <it>Arabidopsis</it>, only one (<it>CalS5</it>) has been directly linked to pollen tube callose. <it>CalS5 </it>orthologues are present in several monocot and eudicot genomes, but little is known about the evolutionary origin of <it>CalS5 </it>or what its ancestral function may have been.</p> <p>Results</p> <p>We investigated expression of <it>CalS </it>in pollen and pollen tubes of selected non-flowering seed plants (gymnosperms) and angiosperms within lineages that diverged below the monocot/eudicot node. First, we determined the nearly full length coding sequence of a <it>CalS5 </it>orthologue from <it>Cabomba caroliniana </it>(<it>CcCalS5</it>) (Nymphaeales). Semi-quantitative RT-PCR demonstrated low <it>CcCalS5 </it>expression within several vegetative tissues, but strong expression in mature pollen. <it>CalS </it>transcripts were detected in pollen tubes of several species within Nymphaeales and Austrobaileyales, and comparative analyses with a phylogenetically diverse group of sequenced genomes indicated homology to <it>CalS5</it>. We also report <it>in silico </it>evidence of a putative <it>CalS5 </it>orthologue from <it>Amborella</it>. Among gymnosperms, <it>CalS5 </it>transcripts were recovered from germinating pollen of <it>Gnetum </it>and <it>Ginkgo</it>, but a novel <it>CalS </it>paralog was instead amplified from germinating pollen of <it>Pinus taeda</it>.</p> <p>Conclusion</p> <p>The finding that CalS5 is the predominant callose synthase in pollen tubes of both early-diverging and model system angiosperms is an indicator of the homology of their novel callosic pollen tube walls and callose plugs. The data suggest that <it>CalS5 </it>had transient expression and pollen-specific functions in early seed plants and was then recruited to novel expression patterns and functions within pollen tube walls in an ancestor of extant angiosperms.</p

Non-equilibrium dynamics and floral trait interactions shape extant angiosperm diversity.

Why are some traits and trait combinations exceptionally common across the tree of life, whereas others are vanishingly rare? The distribution of trait diversity across a clade at any time depends on the ancestral state of the clade, the rate at which new phenotypes evolve, the differences in speciation and extinction rates across lineages, and whether an equilibrium has been reached. Here we examine the role of transition rates, differential diversification (speciation minus extinction) and non-equilibrium dynamics on the evolutionary history of angiosperms, a clade well known for the abundance of some trait combinations and the rarity of others. Our analysis reveals that three character states (corolla present, bilateral symmetry, reduced stamen number) act synergistically as a key innovation, doubling diversification rates for lineages in which this combination occurs. However, this combination is currently less common than predicted at equilibrium because the individual characters evolve infrequently. Simulations suggest that angiosperms will remain far from the equilibrium frequencies of character states well into the future. Such non-equilibrium dynamics may be common when major innovations evolve rarely, allowing lineages with ancestral forms to persist, and even outnumber those with diversification-enhancing states, for tens of millions of years

Nucleosynthesis Constraints on a Massive Gravitino in Neutralino Dark Matter Scenarios

The decays of massive gravitinos into neutralino dark matter particles and Standard Model secondaries during or after Big-Bang nucleosynthesis (BBN) may alter the primordial light-element abundances. We present here details of a new suite of codes for evaluating such effects, including a new treatment based on PYTHIA of the evolution of showers induced by hadronic decays of massive, unstable particles such as a gravitino. We also develop an analytical treatment of non-thermal hadron propagation in the early universe, and use this to derive analytical estimates for light-element production and in turn on decaying particle lifetimes and abundances. We then consider specifically the case of an unstable massive gravitino within the constrained minimal supersymmetric extension of the Standard Model (CMSSM). We present upper limits on its possible primordial abundance before decay for different possible gravitino masses, with CMSSM parameters along strips where the lightest neutralino provides all the astrophysical cold dark matter density. We do not find any CMSSM solution to the cosmological Li7 problem for small m_{3/2}. Discounting this, for m_{1/2} ~ 500 GeV and tan beta = 10 the other light-element abundances impose an upper limit m_{3/2} n_{3/2}/n_\gamma < 3 \times 10^{-12} GeV to < 2 \times 10^{-13} GeV for m_{3/2} = 250 GeV to 1 TeV, which is similar in both the coannihilation and focus-point strips and somewhat weaker for tan beta = 50, particularly for larger m_{1/2}. The constraints also weaken in general for larger m_{3/2}, and for m_{3/2} > 3 TeV we find a narrow range of m_{3/2} n_{3/2}/n_\gamma, at values which increase with m_{3/2}, where the Li7 abundance is marginally compatible with the other light-element abundances.Comment: 74 pages, 40 Figure

Spironolactone in Patients With Heart Failure, Preserved Ejection Fraction, and Worsening Renal Function

BACKGROUND Treatment of heart failure with preserved ejection fraction (HFpEF) with spironolactone is associated with lower risk of heart failure hospitalization (HFH) but increased risk of worsening renal function (WRF). The prognostic implications of spironolactone-associated WRF in HFpEF patients are not well understood. OBJECTIVES The purpose of this study was to investigate the association between WRF, spironolactone treatment, and clinical outcomes in patients with HFpEF. METHODS In 1,767 patients randomized to spironolactone or placebo in the TOPCAT (Treatment of Preserved Cardiac Function Heart Failure With an Aldosterone Antagonist Trial)-Americas study, we examined the incidence of WRF (doubling of serum creatinine) by treatment assignment. Associations between incident WRF and subsequent risk for the primary study endpoint of cardiovascular (CV) death, HFH, or aborted cardiac arrest and key secondary outcomes, including CV death, HFH, and all-cause mortality according to treatment assignment, were examined in time-updated Cox proportional hazards models with an interaction term. RESULTS WRF developed in 260 (14.7%) patients with higher rates in those assigned to spironolactone compared to placebo (17.8% vs. 11.6%; odds ratio: 1.66; 95% confidence interval: 1.27 to 2.17; p < 0.001). Regardless of treatment, incident WRF was associated with increased risk for the primary endpoint (hazard ratio: 2.04; 95% confidence interval: 1.52 to 2.72; p < 0.001) after multivariable adjustment. Although there was no statistical interaction between treatment assignment and WRF regarding the primary endpoint (interaction p = 0.11), spironolactone-associated WRF was associated with lower risk of CV death (interaction p = 0.003) and all-cause mortality (interaction p = 0.001) compared with placebo-associated WRF. CONCLUSIONS Among HFpEF patients enrolled in TOPCAT-Americas, spironolactone increased risk of WRF compared with placebo. Rates of CV death were lower with spironolactone in both patients with and without WRF. (c) 2021 the American College of Cardiology Foundation. Published by Elsevier. All rights reserved

The age patterns of severe malaria syndromes in sub-Saharan Africa across a range of transmission intensities and seasonality settings

BACKGROUND: A greater understanding of the relationship between transmission intensity, seasonality and the age-pattern of malaria is needed to guide appropriate targeting of malaria interventions in different epidemiological settings. METHODS: A systematic literature review identified studies which reported the age of paediatric hospital admissions with cerebral malaria (CM), severe malarial anaemia (SMA), or respiratory distress (RD). Study sites were categorized into a 3 × 2 matrix of Plasmodium falciparum transmission intensity and seasonality. Probability distributions were fitted by maximum likelihood methods, and best fitting models were used to estimate median ages and to represent graphically the age-pattern of each outcome for each transmission category in the matrix. RESULTS: A shift in the burden of CM towards younger age groups was seen with increasing intensity of transmission, but this was not the case for SMA or RD. Sites with 'no marked seasonality' showed more evidence of skewed age-patterns compared to areas of 'marked seasonality' for all three severe malaria syndromes. CONCLUSIONS: Although the peak age of CM will increase as transmission intensity decreases in Africa, more than 75% of all paediatric hospital admissions of severe malaria are likely to remain in under five year olds in most epidemiological settings

Functional distinctiveness of major plant lineages

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106060/1/jec12208.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/106060/2/jec12208-sup-0001-Supp_Info.pd

Shifts in evolutionary lability underlie independent gains and losses of root-nodule symbiosis in a single clade of plants

11 Pág.Root nodule symbiosis (RNS) is a complex trait that enables plants to access atmospheric nitrogen converted into usable forms through a mutualistic relationship with soil bacteria. Pinpointing the evolutionary origins of RNS is critical for understanding its genetic basis, but building this evolutionary context is complicated by data limitations and the intermittent presence of RNS in a single clade of ca. 30,000 species of flowering plants, i.e., the nitrogen-fixing clade (NFC). We developed the most extensive de novo phylogeny for the NFC and an RNS trait database to reconstruct the evolution of RNS. Our analysis identifies evolutionary rate heterogeneity associated with a two-step process: An ancestral precursor state transitioned to a more labile state from which RNS was rapidly gained at multiple points in the NFC. We illustrate how a two-step process could explain multiple independent gains and losses of RNS, contrary to recent hypotheses suggesting one gain and numerous losses, and suggest a broader phylogenetic and genetic scope may be required for genome-phenome mapping.This work was supported by DOE grant DE-SC0018247 to M.K., R.G., P.S., and D.S. and a UFBI grant (University of Florida). We thank Katharina Pawlowski for reviewing our scoring of actinorhizal symbiosis and for related discussions. We thank Colin Hughes and other members of the Legume Phylogeny Working Group for reviewing and helping to resolve taxonomy issues in Leguminosae. We thank Mark Whitten, Kelly Balmant, Chris Dervinis, Joshua Dieringer, and Henry Schmidt for help with specimen sampling.Peer reviewe

Author Correction: Shifts in evolutionary lability underlie independent gains and losses of root-nodule symbiosis in a single clade of plants

Correction to: Nature Communications https://doi.org/10.1038/s41467-024-48036-3, published online 27 May 2024 http://hdl.handle.net/10261/361232Correction to: Nature Communicationshttps://doi.org/10.1038/s41467-024-48036-3, published online 27 May 2024 In this article the funding from the ‘National Science Foundation of China (No. 31720103903)’ was omitted. The original article has been corrected.In this article the funding from the ‘National Science Foundation of China (No. 31720103903) was omitted.Peer reviewe