Sexual dimorphism in water and nitrogen use strategies in Honckenya peploides: timing matters

Aims Sexes of dimorphic species often differ in ecophysiological traits and display spatial segregation. These differences have been interpreted as an evolved response of the sexes to meet the specific resource demands associated with reproduction. Sexes may differ not only in the amount of resources allocated to reproduction but also in the timing of allocation to reproduction. In this study, we hypothesize that as a consequence of their specific resource demands for reproduction, the sexes of the dune plant Honckenya peploides differ in terms of temporal patterns of water use efficiency and nitrogen use and acquisition. Methods Water use efficiency, as inferred from leaf carbon isotope discrimination (Δ13C), nitrogen use, estimated by leaf nitrogen isotope composition (δ15N), and the foliar carbon and nitrogen contents were measured in males and females at three different points in time. Important Findings Females had greater water use efficiency than males, regardless of time. The ratio of N15 to N14 did not change with time in males, but significantly decreased in August for females. The total N content in the leaf tissues of females decreased as the season progressed, while in males a decrease was only found from April to June and then it remained constant from June to August. A similar pattern, but reversed, was followed by the foliar C/N ratio. Additionally, negative relationships between leaf Δ13C and N content were found at all times for males and only at the end of the season for females. Thus, our hypothesis that sex-specific patterns of nitrogen and water use efficiency will depend on time was supported. Overall, our results highlight the importance of including time in studies of sexual dimorphism, and also the role that physiological specialization plays in meeting the specific demands associated with reproduction

Competition between the invasive Impatiens glandulifera and UK native species: the role of soil conditioning and pre-existing resident communities

Himalayan balsam (Impatiens glandulifera) is a highly invasive annual herb that has become extremely prevalent in riparian zones across the UK. The competitive ability of I. glandulifera, both in terms of resource exploitation and allelopathy (i.e., the release of biochemicals that may be toxic to neighbouring plants), is considered a key determinant of its success. Little is known, however, about the effects of the resident community on the establishment and growth of I. glandulifera. Here, we aim to increase our understanding of the competitive ability of this highly invasive plant by investigating the effects of soil conditioning on the performance of four co-occurring native species (Tanacetum vulgare, Urtica dioica, Chelidonium majus and Arabidopsis thaliana). In addition, we also aim to investigate the effect that the pre-existing species composition have on the performance of I. glandulifera seedlings by establishing artificial communities (monocultures and mixtures of four UK native species, including U. dioica). We found negative effects of soil conditioning by I. glandulifera in all four species, either by reducing above-ground biomass, chlorophyll content or both. Monocultures of U. dioica were the only artificial communities that reduced growth of I. glandulifera, and we did not find any support for the idea that a more diverse community may be more resistant to invasion. Our results confirm the high competitive ability of I. glandulifera and highlight how the identity of the natives in the resident community may be key to limit its success

Sexual dimorphism in response to herbivory and competition in the dioecious herb Spinacia oleracea

Sexual dimorphism is common in dioecious plant species and is usually attributed to different cost of reproduction associated with male and female functions. Differences in growth and performance between male and female plants may be accentuated under stress, potentially leading to sex-ratio biases and affecting population growth. Environmental stress involves multiple factors that often occur simultaneously. Among different stress combinations that occur in field conditions, competition and herbivory and their interaction are key biotic factors that can affect plant growth and performance. Here, we conducted a glasshouse experiment in Cardiff, UK, using the cultivated spinach, Spinacia oleracea, as a model system to study sexual dimorphism in intra- and inter-specific competitive ability and in response to herbivory by a generalist herbivore Helix aspersa. We found stronger inter- than intra-specific competition: growth (above-ground biomass) and chlorophyll content of male and female plants was reduced when growing with Brassica oleracea, but not when growing with conspecifics. In the absence of herbivory, females growing with same-sex neighbour had greater root biomass than males; whilst herbivory reduced root biomass significantly only in females competing with same sex neighbours. Plant damage caused by herbivores was similar when growing with male or female conspecifics but greater when growing with B. oleracea. Finally, plant damage caused by herbivores did not differ between male and female plants; however, males increased their allocation to roots and reduced their chlorophyll content after damage. Our results showed that sexual dimorphism occurs in S. oleracea, despite being a worldwide crop, selectively bred for its edible leaves. In particular, our results suggest stronger same-sex competition for females and greater tolerance to herbivory in males than in females of S. oleracea.

Two novel PCR-based assays for sexing of Silene latifolia and Silene dioica plants

Silene latifolia and S. dioica are model systems in studies of plant reproduction, chromosome evolution and sexual dimorphism, but sexing of plants based on morphology is only possible from flowering stage onwards. Both species show homogametic females (XX) and heterogametic males (XY). • Here we developed two assays (primer pairs ss816 and ss441) for molecular sexing of S. latifolia and S. dioica, targeting length polymorphisms between the X and Y-linked copies of the spermidine synthase gene. The two assays were successful in identifying known (flowering-stage) males and females from UK and Spanish populations, with an error rate of 3.1% (ss816; successful for both species) and 0% (ss441, only successful for S. latifolia). Our assays therefore represent novel tools for rapid, robust and simple determination of the genotypic sex of S. latifolia and S. dioica

Sex and heavy metals: study of sexual dimorphism in response to soil pollution

In dioecious plants, males and females often show distinct morphological, physiological and life history traits as result of their different demands for reproduction. Such sexual dimorphism is likely to be accentuated under stressful conditions, such as that imposed by exposure to heavy metals. However little is known about the response of dioecious plants to stress by heavy metals. Here we use the dioecious herb Silene latifolia to investigate the growth and reproduction of males and females growing in soil polluted with either Cu or Cd. We also examined whether the sexes differed in the patterns of metal accumulation in their tissues. Patterns of biomass allocation to reproduction, roots, leaves and shoots (stem and leaves) were compared in male and female S. latifolia plants that were harvested after growing for 14 weeks in different soil conditions (non-polluted soil, Cu-polluted soil and Cd-polluted soil). In addition, patterns of metal accumulation between the sexes were also compared post-harvest by analysing the metal content in their tissues. Overall, metals decreased plants’ total dry mass allocated to leaves and to roots- particularly in males. Females accumulated more Cu in their tissues. However, this did not seem to correspond with females performing worse (in terms of growth and reproduction) than males when growing in soil polluted with this metal. Despite males and females having similar levels of Cd in their tissues, males seemed to have lower tolerance to this metal, as indicated by a lower total and leaf dry mass than females, and also by a lower number of flowers when growing in Cd-polluted soil. We also found contrasting differences in female seed production due to heavy metals, with number of seeds (but not mass) decreasing with Cu and increasing with Cd. Our results indicate the presence of sexual dimorphism in response to heavy metals, with the sexes differing in both patterns of accumulation and tolerance

Genome-wide structural variant analysis identifies risk loci for non-Alzheimer’s dementias

We characterized the role of structural variants, a largely unexplored type of genetic variation, in two non-Alzheimer’s dementias, namely Lewy body dementia (LBD) and frontotemporal dementia (FTD)/amyotrophic lateral sclerosis (ALS). To do this, we applied an advanced structural variant calling pipeline (GATK-SV) to short-read whole-genome sequence data from 5,213 European-ancestry cases and 4,132 controls. We discovered, replicated, and validated a deletion in TPCN1 as a novel risk locus for LBD and detected the known structural variants at the C9orf72 and MAPT loci as associated with FTD/ALS. We also identified rare pathogenic structural variants in both LBD and FTD/ALS. Finally, we assembled a catalog of structural variants that can be mined for new insights into the pathogenesis of these understudied forms of dementia

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

Correction to: Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

The original version of this article unfortunately contained a mistake

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

Sex-specific physiological, allocation and growth responses to water availability in the subdioecious plantHonckenya peploides

The gender of dimorphic plant species is often affected by ecophysiological variables. Differences have been interpreted as a response of the sexes to meet specific resource demands associated with reproduction. This study investigated whether sex-specific variations in ecophysiological traits in response to water availability determine the performance of each sex in different habitats, and therefore promote extreme spatial segregation of the sexes in the subdioecious plant, Honckenya peploides. Twenty-seven plants of each sex were individually potted in dune sand and assigned randomly to one of three water treatments. Well-watered plants were watered daily to field capacity, whereas plants in the moderate and high-water stress treatments received 40% and 20%, respectively, of the water given to well-watered plants. Photochemical efficiency, leaf spectral properties and components of relative growth rate (leaf area ratio and net assimilation rate) were measured. Photochemical efficiencies integrated over time were higher in male than in female plants. Water deficit decreased maximum quantum yield in female plants more rapidly than in male plants, but female plants (unlike male plants) had recovered to initial values by the end of the experiment. Maximum quantum yield in male plants was more affected by water stress than in female plants, indicating that male plants were more susceptible to photoinhibition. The two sexes did not differ in growth rate, but male plants invested a higher proportion of their biomass in leaves, had a higher leaf area per unit biomass and lower net assimilation rate relative to female plants. Female plants had a higher water content and succulence than male plants. Differences in stomatal density between the sexes depended on water availability. The results suggest that the two sexes of H. peploides have different strategies for coping with water stress. The study also provides evidence of sex differences in allocation traits. We conclude that between-sex differences in ecophysiological and allocation traits may contribute to explain habitat-related between-sex differences in performance and, therefore, the spatial segregation of the sexes