On the road to diploidization? Homoeolog loss in independently formed populations of the allopolyploid Tragopogon miscellus (Asteraceae)

<p>Abstract</p> <p>Background</p> <p>Polyploidy (whole-genome duplication) is an important speciation mechanism, particularly in plants. Gene loss, silencing, and the formation of novel gene complexes are some of the consequences that the new polyploid genome may experience. Despite the recurrent nature of polyploidy, little is known about the genomic outcome of independent polyploidization events. Here, we analyze the fate of genes duplicated by polyploidy (homoeologs) in multiple individuals from ten natural populations of <it>Tragopogon miscellus </it>(Asteraceae), all of which formed independently from <it>T. dubius </it>and <it>T. pratensis </it>less than 80 years ago.</p> <p>Results</p> <p>Of the 13 loci analyzed in 84 <it>T. miscellus </it>individuals, 11 showed loss of at least one parental homoeolog in the young allopolyploids. Two loci were retained in duplicate for all polyploid individuals included in this study. Nearly half (48%) of the individuals examined lost a homoeolog of at least one locus, with several individuals showing loss at more than one locus. Patterns of loss were stochastic among individuals from the independently formed populations, except that the <it>T. dubius </it>copy was lost twice as often as <it>T. pratensis</it>.</p> <p>Conclusion</p> <p>This study represents the most extensive survey of the fate of genes duplicated by allopolyploidy in individuals from natural populations. Our results indicate that the road to genome downsizing and ultimate genetic diploidization may occur quickly through homoeolog loss, but with some genes consistently maintained as duplicates. Other genes consistently show evidence of homoeolog loss, suggesting repetitive aspects to polyploid genome evolution.</p

Interaction of GABA and Excitatory Amino Acids in the Basolateral Amygdala: Role in Cardiovascular Regulation

Activation of the amygdala in rats produces cardiovascular changes that include increases in heart rate and arterial pressure as well as behavioral changes characteristic of emotional arousal. The objective of the present study was to examine the interaction of GABA and excitatory amino acid (EAA) receptors in the basolateral amygdala (BLA) in regulating cardiovascular function. Microinjection of the GABAA receptor antagonist bicuculline methiodide (BMI) or the E A A receptor agonists NMDA or AMPA into the same region of the BLA of conscious rats produced dose-related increases in heart rate and arterial pressure. Injection of the nonselective EAA receptor antagonist kynurenic acid into the BLA prevented or reversed the cardiovascular changes caused by local injection of BMI or the noncompetitive GABA antagonist picrotoxin. Conversely, local pretreatment with the glutamate reuptake inhibitorl-trans-pyrrolidine-2,4-dicarboxylic acid enhanced the effects of intra-amygdalar injection of BMI. The cardiovascular effects of BMI were also attenuated by injection of either the NMDA antagonist 3-(2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP) or the AMPA receptor antagonist 1,2,3,4-tetrahydro-6-nitro-2,3-dioxo-benzo[f]quinoxaline-7-sulfonamide (NBQX). When these two EAA receptor antagonists were combined, their ability to suppress BMI-induced tachycardic and pressor responses was additive. These findings indicate that the cardiovascular effects caused by blockade of GABAergic inhibition in the BLA of the rat are dependent on activation of local NMDA and AMPA receptors

ICU Made 4 U: Critical Care Education for Novice Nurses

Background: The novel Coronavirus 2019 (COVID 19) pandemic had a large impact on education in the healthcare setting. At Henry Ford Jackson Hospital (HFJH), due to staffing constraints and emergent clinical needs, nurses hired during the COVID 19 pandemic did not complete standard critical care orientation after March 2020. During yearly learning needs assessments, nurses identified opportunities for enhanced education regarding the management of critically ill patients. Staff Development Educators and Clinical Nurse Specialists (CNSs) within the acuity adaptable units identified a gap in knowledge regarding critical care concepts. At HFJH, acuity adaptable units house critical care patients on the Medical Universal Bed unit and the Surgical Universal Bed unit. Aim: The aim of this quality improvement project was to increase novice nurses’ knowledge of critical care concepts while increasing confidence implementing advanced nursing skills within the patient population. Methods: The Staff Development Educators and CNSs proposed an education program to the nursing leadership and gained support for mandatory attendance. Content was formulated based on input from the interprofessional critical care team and feedback from the nursing learning needs assessments. Nurses caring for the critical care population hired or transferred after March 2020 were required to complete the program. Nurses were given the opportunity to complete and pass a standardized test (score of 80% or higher) in lieu of attending the educational sessions. Three, four-hour sessions were created and included didactic content, simulation with case scenarios, and interactive teaching methods with equipment specific to the intensive care setting. A pre-test was administered prior to content presentation and the post test was administered at the end of the third session. Nurses completed an evaluation for each didactic content presentation and received continuing education credit. Findings: The average score for pre-test was 70.7%. The average post test score was 77.3%. Demonstrating a 6.6% increase following intervention. The results of this quality improvement project indicated that formalized, didactic and simulation education opportunities enhanced the knowledge of critical care concepts for novice nurses. Nurses completed an evaluation for each didactic session with positive feedback and suggestions for additional content. Implications: Nurses with critical care experience opted to participate in the program to enhance their personal growth and knowledge. Based on the pre and post test results, gastrointestinal and parenteral content will be added to future sessions. Tailored education, with a focus on simulation and hands on content, showed to improve nurses understanding of advanced critical care concepts. These didactic, simulation, and hands on learning sessions will be integrated into the onboarding orientation for nurses caring for the critical care population.https://scholarlycommons.henryford.com/nursresconf2023/1004/thumbnail.jp

Similar patterns of rDNA evolution in synthetic and recently formed natural populations of Tragopogon (Asteraceae) allotetraploids

<p>Abstract</p> <p>Background</p> <p><it>Tragopogon mirus </it>and <it>T. miscellus </it>are allotetraploids (2<it>n </it>= 24) that formed repeatedly during the past 80 years in eastern Washington and adjacent Idaho (USA) following the introduction of the diploids <it>T. dubius</it>, <it>T. porrifolius</it>, and <it>T. pratensis </it>(2<it>n </it>= 12) from Europe. In most natural populations of <it>T. mirus </it>and <it>T. miscellus</it>, there are far fewer 35S rRNA genes (rDNA) of <it>T. dubius </it>than there are of the other diploid parent (<it>T. porrifolius </it>or <it>T. pratensis</it>). We studied the inheritance of parental rDNA loci in allotetraploids resynthesized from diploid accessions. We investigate the dynamics and directionality of these rDNA losses, as well as the contribution of gene copy number variation in the parental diploids to rDNA variation in the derived tetraploids.</p> <p>Results</p> <p>Using Southern blot hybridization and fluorescent <it>in situ </it>hybridization (FISH), we analyzed copy numbers and distribution of these highly reiterated genes in seven lines of synthetic <it>T. mirus </it>(110 individuals) and four lines of synthetic <it>T. miscellus </it>(71 individuals). Variation among diploid parents accounted for most of the observed gene imbalances detected in F₁hybrids but cannot explain frequent deviations from repeat additivity seen in the allotetraploid lines. Polyploid lineages involving the same diploid parents differed in rDNA genotype, indicating that conditions immediately following genome doubling are crucial for rDNA changes. About 19% of the resynthesized allotetraploid individuals had equal rDNA contributions from the diploid parents, 74% were skewed towards either <it>T. porrifolius </it>or <it>T. pratensis</it>-type units, and only 7% had more rDNA copies of <it>T. dubius</it>-origin compared to the other two parents. Similar genotype frequencies were observed among natural populations. Despite directional reduction of units, the additivity of 35S rDNA locus number is maintained in 82% of the synthetic lines and in all natural allotetraploids.</p> <p>Conclusions</p> <p>Uniparental reductions of homeologous rRNA gene copies occurred in both synthetic and natural populations of <it>Tragopogon </it>allopolyploids. The extent of these rDNA changes was generally higher in natural populations than in the synthetic lines. We hypothesize that locus-specific and chromosomal changes in early generations of allopolyploids may influence patterns of rDNA evolution in later generations.</p

Transcriptomic Shock Generates Evolutionary Novelty in a Newly Formed, Natural Allopolyploid Plant

SummaryNew hybrid species might be expected to show patterns of gene expression intermediate to those shown by parental species [1, 2]. “Transcriptomic shock” may also occur, in which gene expression is disrupted; this may be further modified by whole genome duplication (causing allopolyploidy) [3–16]. “Shock” can include instantaneous partitioning of gene expression between parental copies of genes among tissues [16–19]. These effects have not previously been studied at a population level in a natural allopolyploid plant species. Here, we survey tissue-specific expression of 144 duplicated gene pairs derived from different parental species (homeologs) in two natural populations of 40-generation-old allotetraploid Tragopogon miscellus (Asteraceae) plants. We compare these results with patterns of allelic expression in both in vitro “hybrids” and hand-crossed F1 hybrids between the parental diploids T. dubius and T. pratensis, and with patterns of homeolog expression in synthetic (S1) allotetraploids. Partitioning of expression was frequent in natural allopolyploids, but F1 hybrids and S1 allopolyploids showed less partitioning of expression than the natural allopolyploids and the in vitro “hybrids” of diploid parents. Our results suggest that regulation of gene expression is relaxed in a concerted manner upon hybridization, and new patterns of partitioned expression subsequently emerge over the generations following allopolyploidization

Seasonal variation in effects of herbivory on foliar nitrogen of a threatened conifer

Invasive herbivores can dramatically impact the nitrogen (N) economy of native hosts. In deciduous species, most N is stored in stem tissues, while in evergreen conifer species N is stored in needles, making them potentially more vulnerable to herbivory. In eastern forests of the USA, the long-lived, foundational conifer eastern hemlock (Tsuga canadensis) is under the threat of extirpation by the invasive hemlock woolly adelgid (HWA: Adelges tsugae). We assessed the impact of HWA infestation on the patterns of seasonal foliar N availability in hemlock planted in a deciduous forest understory. Over the course of a year, we sampled needles and twigs and measured N, carbon (C), C:N ratio, and total protein concentrations. Tissue sampling events were timed to coincide with key life-history transitions for HWA to determine the association between HWA development and feeding with these foliar nutrients. In uninfested trees, needle and twig N concentrations fluctuated across seasons, indicating the potential importance of N storage and remobilization for the N economy of eastern hemlock. Although N levels in HWA-infested trees also cycled annually, the degree to which N concentrations fluctuated seasonally in tissues was significantly affected by HWA feeding. These fluctuations exceeded N levels observed in control trees and coincided with HWA feeding. HWA feeding generally increased N concentrations but did not affect protein levels, suggesting that changes in N do not occur via adelgid-induced protein breakdown. Herbivore-induced mobilization of N to feeding sites and its rapid depletion may be a significant contributor to eastern hemlock mortality in US forests

Rapid Chromosome Evolution in Recently Formed Polyploids in Tragopogon (Asteraceae)

Polyploidy, frequently termed "whole genome duplication", is a major force in the evolution of many eukaryotes. Indeed, most angiosperm species have undergone at least one round of polyploidy in their evolutionary history. Despite enormous progress in our understanding of many aspects of polyploidy, we essentially have no information about the role of chromosome divergence in the establishment of young polyploid populations. Here we investigate synthetic lines and natural populations of two recently and recurrently formed allotetraploids Tragopogon mirus and T. miscellus (formed within the past 80 years) to assess the role of aberrant meiosis in generating chromosomal/genomic diversity. That diversity is likely important in the formation, establishment and survival of polyploid populations and species.Applications of fluorescence in situ hybridisation (FISH) to natural populations of T. mirus and T. miscellus suggest that chromosomal rearrangements and other chromosomal changes are common in both allotetraploids. We detected extensive chromosomal polymorphism between individuals and populations, including (i) plants monosomic and trisomic for particular chromosomes (perhaps indicating compensatory trisomy), (ii) intergenomic translocations and (iii) variable sizes and expression patterns of individual ribosomal DNA (rDNA) loci. We even observed karyotypic variation among sibling plants. Significantly, translocations, chromosome loss, and meiotic irregularities, including quadrivalent formation, were observed in synthetic (S(0) and S(1) generations) polyploid lines. Our results not only provide a mechanism for chromosomal variation in natural populations, but also indicate that chromosomal changes occur rapidly following polyploidisation.These data shed new light on previous analyses of genome and transcriptome structures in de novo and establishing polyploid species. Crucially our results highlight the necessity of studying karyotypes in young (<150 years old) polyploid species and synthetic polyploids that resemble natural species. The data also provide insight into the mechanisms that perturb inheritance patterns of genetic markers in synthetic polyploids and populations of young natural polyploid species

Why sequence all eukaryotes?

Life on Earth has evolved from initial simplicity to the astounding complexity we experience today. Bacteria and archaea have largely excelled in metabolic diversification, but eukaryotes additionally display abundant morphological innovation. How have these innovations come about and what constraints are there on the origins of novelty and the continuing maintenance of biodiversity on Earth? The history of life and the code for the working parts of cells and systems are written in the genome. The Earth BioGenome Project has proposed that the genomes of all extant, named eukaryotes-about 2 million species-should be sequenced to high quality to produce a digital library of life on Earth, beginning with strategic phylogenetic, ecological, and high-impact priorities. Here we discuss why we should sequence all eukaryotic species, not just a representative few scattered across the many branches of the tree of life. We suggest that many questions of evolutionary and ecological significance will only be addressable when whole-genome data representing divergences at all of the branchings in the tree of life or all species in natural ecosystems are available. We envisage that a genomic tree of life will foster understanding of the ongoing processes of speciation, adaptation, and organismal dependencies within entire ecosystems. These explorations will resolve long-standing problems in phylogenetics, evolution, ecology, conservation, agriculture, bioindustry, and medicine

Outbreak of Pneumonia in the Setting of Fatal Pneumococcal Meningitis among US Army Trainees: Potential Role of Chlamydia pneumoniae Infection

<p>Abstract</p> <p>Background</p> <p>Compared to the civilian population, military trainees are often at increased risk for respiratory infections. We investigated an outbreak of radiologically-confirmed pneumonia that was recognized after 2 fatal cases of serotype 7F pneumococcal meningitis were reported in a 303-person military trainee company (Alpha Company).</p> <p>Methods</p> <p>We reviewed surveillance data on pneumonia and febrile respiratory illness at the training facility; conducted chart reviews for cases of radiologically-confirmed pneumonia; and administered surveys and collected nasopharyngeal swabs from trainees in the outbreak battalion (Alpha and Hotel Companies), associated training staff, and trainees newly joining the battalion.</p> <p>Results</p> <p>Among Alpha and Hotel Company trainees, the average weekly attack rates of radiologically-confirmed pneumonia were 1.4% and 1.2% (most other companies at FLW: 0-0.4%). The pneumococcal carriage rate among all Alpha Company trainees was 15% with a predominance of serotypes 7F and 3. <it>Chlamydia pneumoniae </it>was identified from 31% of specimens collected from Alpha Company trainees with respiratory symptoms.</p> <p>Conclusion</p> <p>Although the etiology of the outbreak remains unclear, the identification of both <it>S. pneumoniae </it>and <it>C. pneumoniae </it>among trainees suggests that both pathogens may have contributed either independently or as cofactors to the observed increased incidence of pneumonia in the outbreak battalion and should be considered as possible etiologies in outbreaks of pneumonia in the military population.</p

Structural conservation of an ancient tRNA sensor in eukaryotic glutaminyl-tRNA synthetase

In all organisms, aminoacyl tRNA synthetases covalently attach amino acids to their cognate tRNAs. Many eukaryotic tRNA synthetases have acquired appended domains, whose origin, structure and function are poorly understood. The N-terminal appended domain (NTD) of glutaminyl-tRNA synthetase (GlnRS) is intriguing since GlnRS is primarily a eukaryotic enzyme, whereas in other kingdoms Gln-tRNAGln is primarily synthesized by first forming Glu-tRNAGln, followed by conversion to Gln-tRNAGln by a tRNA-dependent amidotransferase. We report a functional and structural analysis of the NTD of Saccharomyces cerevisiae GlnRS, Gln4. Yeast mutants lacking the NTD exhibit growth defects, and Gln4 lacking the NTD has reduced complementarity for tRNAGln and glutamine. The 187-amino acid Gln4 NTD, crystallized and solved at 2.3 Å resolution, consists of two subdomains, each exhibiting an extraordinary structural resemblance to adjacent tRNA specificity-determining domains in the GatB subunit of the GatCAB amidotransferase, which forms Gln-tRNAGln. These subdomains are connected by an apparent hinge comprised of conserved residues. Mutation of these amino acids produces Gln4 variants with reduced affinity for tRNAGln, consistent with a hinge-closing mechanism proposed for GatB recognition of tRNA. Our results suggest a possible origin and function of the NTD that would link the phylogenetically diverse mechanisms of Gln-tRNAGln synthesis