CONTENTS: Summary 752 I. Introduction 752 II. Will migration be enough? 753 III. Can adaptation proceed fast enough? 754 IV. Fitness links demographic and evolutionary processes 755 V. Experimental ...studies: what do they tell us and how can we improve them? 756 VI. Predicting evolutionary change based on genetic variation and natural selection 757 VII. The chronosequence approach 758 VIII. Resurrection of ancestral propagules 759 IX. The mean and variance in fitness, a link between genetics and demography 760 X. Conclusions 762 Acknowledgements 762 References 762 SUMMARY: Evolution proceeds unceasingly in all biological populations. It is clear that climate‐driven evolution has molded plants in deep time and within extant populations. However, it is less certain whether adaptive evolution can proceed sufficiently rapidly to maintain the fitness and demographic stability of populations subjected to exceptionally rapid contemporary climate change. Here, we consider this question, drawing on current evidence on the rate of plant range shifts and the potential for an adaptive evolutionary response. We emphasize advances in understanding based on theoretical studies that model interacting evolutionary processes, and we provide an overview of quantitative genetic approaches that can parameterize these models to provide more meaningful predictions of the dynamic interplay between genetics, demography and evolution. We outline further research that can clarify both the adaptive potential of plant populations as climate continues to change and the role played by ongoing adaptation in their persistence.
Stimulated by the Large Hadron Collider and the search for the elusive Higgs Boson, interest in particle physics continues at a high level among scientists and the general public. This book includes ...theoretical aspects, with chapters outlining the generation model and a charged Higgs boson model as alternative scenarios to the Standard Model. An introduction is provided to postulated axion photon interactions and associated photon dispersion in magnetized media. The complexity of particle physics research requiring the synergistic combination of theory, hardware and computation is described in terms of the e-science paradigm. The book concludes with a chapter tackling potential radiation hazards associated with extremely weakly interacting neutrinos if produced in copious amounts with future high-energy muon-collider facilities.
Tree taxa shifted latitude or elevation range in response to changes in Quaternary climate. Because many modern trees display adaptive differentiation in relation to latitude or elevation, it is ...likely that ancient trees were also so differentiated, with environmental sensitivities of populations throughout the range evolving in conjunction with migrations. Rapid climate changes challenge this process by imposing stronger selection and by distancing populations from environments to which they are adapted. The unprecedented rates of climate changes anticipated to occur in the future, coupled with land use changes that impede gene flow, can be expected to disrupt the interplay of adaptation and migration, likely affecting productivity and threatening the persistence of many species.
During the current coronavirus pandemic, social distancing and restrictions on travel have resulted in a dramatic rise in the use of technology (including video conferencing) for remote meetings. ...From local multidisciplinary team (MDT) meetings to national and international committees, this form of communication has been vital to ensure patient-related and other business can continue, albeit in a sometimes unfamiliar environment.
In this article we consider some of the human factors elements of remote meetings and provide suggestions to enhance the experience of team and committee members during this unsettling time. It is possible that this form of communication will continue to flourish after the pandemic is over.
We characterized the genetic architecture of three populations of a native North American prairie plant in field conditions that simulate the warmer and more arid climates predicted by global climate ...models. Despite genetic variance for traits under selection, among-trait genetic correlations that are antagonistic to the direction of selection limit adaptive evolution within these populations. Predicted rates of evolutionary response are much slower than the predicted rate of climate change.
Mesenchymal stem cells (MSCs) within their native environment of the stem cell niche in bone receive biochemical stimuli from surrounding cells. These stimuli likely influence how MSCs differentiate ...to become bone precursors. The ability of MSCs to undergo osteogenic differentiation is well established in vitro;however, the role of the natural cues from bone's regulatory cells, osteocytes and osteoblasts in regulating the osteogenic differentiation of MSCs in vivo are unclear. In this study we delineate the role of biochemical signalling from osteocytes and osteoblasts, using conditioned media and co-culture experiments, to understand how they direct osteogenic differentiation of MSCs. Furthermore, the synergistic relationship between osteocytes and osteoblasts is examined by transwell co-culturing of MSCs with both simultaneously. Osteogenic differentiation of MSCs was quantified by monitoring alkaline phosphatase (ALP) activity, calcium deposition and cell number. Intracellular ALP was found to peak earlier and there was greater calcium deposition when MSCs were co-cultured with osteocytes rather than osteoblasts, suggesting that osteocytes are more influential than osteoblasts in stimulating osteogenesis in MSCs. Osteoblasts initially stimulated an increase in the number of MSCs, but ultimately regulated MSC differentiation down the same pathway. Our novel co-culture system confirmed a synergistic relationship between osteocytes and osteoblasts in producing biochemical signals to stimulate the osteogenic differentiation of MSCs. This study provides important insights into the mechanisms at work within the native stem cell niche to stimulate osteogenic differentiation and outlines a possible role for the use of co-culture or conditioned media methodologies for tissue engineering applications.
Abstract A near-infrared spectrum of nova V1716 Scorpii (PNV J17224490-4137160), a recent bright ( V max = 7.3 mag), Fermi-LAT detected γ -ray source, was modeled using the photoionization code ...CLOUDY. Abundances were estimated for He, C, N, O, Si, Al, Mg, Fe, Ne, S, Ca, and P. Notably, P (a factor of 120) and N (a factor of 248) are highly overabundant. It was necessary to assume the ejecta consist of two components (with a cylindrical geometry): a dense component from which the bulk of the H, He, and neutral O i and N emission arises and a more diffuse component from which most of the coronal lines arise. Some of the coronal lines are found to originate from both the dense and diffuse components. The mass of the ejecta, including neutral and ionized gas, is ≃4.19 × 10 −4 M ⊙ . Our analysis indicates that in the case of V1716 Sco (which has a carbon–oxygen white dwarf), a fraction of 25% white dwarf matter rather than 50% is favored for the mixing between a white dwarf and the accreted envelope before the outburst. This mixing ratio is like that found for oxygen–neon novae where a 25% mixing fraction is also indicated. Helium hydride—the first molecule to form after the Big Bang—may have formed in the ejecta of V1716 Sco based on photoionization modeling. This prediction suggests that novae may be potential formation sites of this important molecular ion.
Acute exacerbation of COPD Ko, Fanny W.; Chan, Ka Pang; Hui, David S. ...
Respirology,
October 2016, Volume:
21, Issue:
7
Journal Article
Peer reviewed
Open access
The literature of acute exacerbation of chronic obstructive pulmonary disease (COPD) is fast expanding. This review focuses on several aspects of acute exacerbation of COPD (AECOPD) including ...epidemiology, diagnosis and management. COPD poses a major health and economic burden in the Asia‐Pacific region, as it does worldwide. Triggering factors of AECOPD include infectious (bacteria and viruses) and environmental (air pollution and meteorological effect) factors. Disruption in the dynamic balance between the ‘pathogens’ (viral and bacterial) and the normal bacterial communities that constitute the lung microbiome likely contributes to the risk of exacerbations. The diagnostic approach to AECOPD varies based on the clinical setting and severity of the exacerbation. After history and examination, a number of investigations may be useful, including oximetry, sputum culture, chest X‐ray and blood tests for inflammatory markers. Arterial blood gases should be considered in severe exacerbations, to characterize respiratory failure. Depending on the severity, the acute management of AECOPD involves use of bronchodilators, steroids, antibiotics, oxygen and noninvasive ventilation. Hospitalization may be required, for severe exacerbations. Nonpharmacological interventions including disease‐specific self‐management, pulmonary rehabilitation, early medical follow‐up, home visits by respiratory health workers, integrated programmes and telehealth‐assisted hospital at home have been studied during hospitalization and shortly after discharge in patients who have had a recent AECOPD. Pharmacological approaches to reducing risk of future exacerbations include long‐acting bronchodilators, inhaled steroids, mucolytics, vaccinations and long‐term macrolides. Further studies are needed to assess the cost‐effectiveness of these interventions in preventing COPD exacerbations.
Immunoglobulin A (IgA) is prominently secreted at mucosal surfaces and coats a fraction of the intestinal microbiota. However, the commensal bacteria bound by IgA are poorly characterized and the ...type of humoral immunity they elicit remains elusive. We used bacterial flow cytometry coupled with 16S rRNA gene sequencing (IgA-Seq) in murine models of immunodeficiency to identify IgA-bound bacteria and elucidate mechanisms of commensal IgA targeting. We found that residence in the small intestine, rather than bacterial identity, dictated induction of specific IgA. Most commensals elicited strong T-independent (TI) responses that originated from the orphan B1b lineage and from B2 cells, but excluded natural antibacterial B1a specificities. Atypical commensals including segmented filamentous bacteria and Mucispirillum evaded TI responses but elicited T-dependent IgA. These data demonstrate exquisite targeting of distinct commensal bacteria by multiple layers of humoral immunity and reveal a specialized function of the B1b lineage in TI mucosal IgA responses.
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•IgA predominantly targets commensal bacteria that reside in the small intestine•Most commensal bacteria elicit strong T-independent IgA responses•A minor subset of bacteria evade T-independent IgA and elicit T-dependent responses•The orphan B1b lineage is a prominent source of commensal-specific IgA
Bendelac and colleagues find that homeostatic IgA responses target commensal bacteria that reside in the small intestine but exclude bacteria indigenous to the colon. Most commensals are targeted by T-independent IgA derived predominantly from the orphan B1b lineage, but atypical subsets evade T-independent responses and elicit T-dependent IgA.
Background. Necrotizing enterocolitis (NEC) is a devastating inflammatory bowel disease of premature infants speculatively associated with infection. Suspected NEC can be indistinguishable from ...sepsis, and in established cases an infant may die within hours of diagnosis. Present treatment is supportive. A means of presymptomatic diagnosis is urgently needed. We aimed to identify microbial signatures in the gastrointestinal microbiota preceding NEC diagnosis in premature infants. Methods. Fecal samples and clinical data were collected from a 2-year cohort of 369 premature neonates. Next-generation sequencing of 16S ribosomal RNA gene regions was used to characterize the microbiota of prediagnosis fecal samples from 12 neonates with NEC, 8 with suspected NEC, and 44 controls. Logistic regression was used to determine clinical characteristics and operational taxonomic units (OTUs) discriminating cases from controls. Samples were cultured and isolates identified using matrix-assisted laser desorption/ionization–time of flight. Clostridial isolates were typed and toxin genes detected. Results. A clostridial OTU was overabundant in prediagnosis samples from infants with established NEC (P = .006). Culture confirmed the presence of Clostridium perfringens type A. Fluorescent amplified fragment-length polymorphism typing established that no isolates were identical. Prediagnosis samples from NEC infants not carrying profuse C. perfringens revealed an overabundance of a Klebsiella OTU (P = .049). Prolonged continuous positive airway pressure (CPAP) therapy with supplemental oxygen was also associated with increased NEC risk. Conclusions. Two fecal microbiota signatures (Clostridium and Klebsiella OTUs) and need for prolonged CPAP oxygen signal increased risk of NEC in presymptomatic infants. These biomarkers will assist development of a screening tool to allow very early diagnosis of NEC.
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