Invasive plant species thresholds in the forests of Robinson Crusoe Island,Chile

Background: Invasion by exotic plants worldwide can lead to the loss of native species, particularly on islands with a high proportion of endemic plants, such as Robinson Crusoe Island (RCI).

Aims: We studied the two most invasive exotic plant species occurring in the forest of RCI: Aristotelia chilensis and Rubus ulmifolius. We aimed at establishing thresholds for environmental and microsite variables related to invasion.

Methods: Environmental and forest understorey variables, including canopy gaps and invasive species cover were measured in non-invaded and invaded forest sites. We expected more invasion in plots located close to invasive shrublands, and in large gaps with high solar radiation.

Results: We found no relationship between the distance to invasive shrublands and invasion probability. Solar radiation tended to be slightly related with a higher cover of R. ulmifolius, the most abundant invasive exotic plant in RCI forests. Overall, the cover of native ferns appeared to inhibit invasion.

Conclusions: The identification of variable thresholds related to invasion can be useful for guiding management decisions. Our results suggest that management should consider monitoring forest canopy gap formation and promote the establishment of ferns to reduce the probability of invasive species establishing.     

Dynamic variation of histone H3 trimethyl Lys4 (H3K4me3) and heterochromatin protein 1 (HP1) with employment length in nickel smelting workers

Objective: To investigate the dynamic variation in H3K4me3 and HP1 with employment length in nickel smelting workers.

Methods: Blood samples were collected from 140 nickel smelting workers and 140 age-matched office workers to test for H3K4me3, and HP1 levels.

Results: H3K4me3 was statistically significantly different (p?<?0.05) between the two groups and positively correlated with employment length (r_s?=_?0.267). HP1 was not correlated with employment length (p?=?0.066) but was significantly different between the two groups.

Conclusions: Chronic exposure to nickel can induce oxidative damage, and increase H3K4me3 expression and inhibit HP1 expression.     

Inter-regional hybrids of native and non-native Centaurea sulphurea inherit increased competitive ability from the non-natives

Background: Exotic species can rapidly develop adaptations to their non-native regions, such as increased size and competitive ability. Although these traits are believed to be responsible for invasive success, some non-invasive exotic species display them too. This suggests that increased size and competitive ability might be necessary but not sufficient to turn an exotic into a successful invader.

Aim: To assess size and competitive ability of the exotic non-invasive weed Centaurea sulphurea, and of inter-regional hybrids between native and non-native populations.

Methods: We experimentally produced a cohort of C. sulphurea individuals from the native range of the species in Spain, from its non-native range in California, as well as hybrids between the two regions. We grew these plants in pots in competition with the grass Bromus hordeaceus, or alone in control pots.

Results: Individuals from California were larger and better competitors than individuals from Spain. Furthermore, inter-regional hybrids showed competitive responses similar to that of individuals from California.

Conclusions: Our results confirm that increased competitive ability might be more frequent than previously thought among introduced species, since it can be detected in at least some exotic non-invasive species. They also illustrate the importance of maternal effects, how locally adapted traits are conserved and spread in the non-native ranges of exotic species, and suggest that plant size and competitive ability are not directly associated in this species.     

Self-pollination,style length development and seed set in self-compatible Asteraceae: evidence from Senecio vulgaris L.

Background: Variation in style length has been reported in Senecio vulgaris and has been associated with outcrossing rate.

Aims: To determine if (i) long styles lack germinated pollen on stigmas left to self-pollinate, (ii) successful self-pollination causes styles to stop elongating and shrink in length and (iii) seed set increases with the amount of pollen deposited on stigmas.

Methods: Determined germinated self-pollen on stigmas of long and short styles after auto-self-pollination; scored style length over 48 h in self-pollinated and non-pollinated florets; recorded seed set after placing different amounts of pollen on stigmas.

Results: Most long-styled florets had zero or low amounts of germinated pollen on stigmas in contrast to most short-styled florets. Styles initially elongated to the same length in self-pollinated and non-pollinated florets, then shrank in length in self-pollinated florets while continuing to elongate in non-pollinated florets. Seed set increased with number of pollen grains deposited on stigmas.

Conclusions: Successful self-pollen deposition and/or germination on stigmas of S. vulgaris are indicated by presence of short styles, whereas the opposite is indicated by presence of long styles in florets left to self-pollinate. Self-pollination causes styles to shrink after initially elongating. Seed set is dependent on the amount of pollen deposited on stigmas.     

Biosystematic studies on the mountain plant Gentiana lutea L. reveal variability in reproductive traits among subspecies

Background: Taxonomic analysis provides a basic understanding for taxon identification and contributes to preliminary information for several branches of applied biology, while studies on reproductive strategies and plant fitness are essential to interpret population status and dynamics.

Aims: We tested the reliability of diagnostic characters for identification and to characterise sexual resource allocation, the breeding system and seed predation among subspecies of Gentiana lutea.

Methods: We analysed morphological characters in 70 herbarium specimens. In five natural populations we counted pollen and ovule numbers, assessed reproductive output after pollination treatments and evaluated pre-dispersal predation.

Results: Taxonomic traits previously indicated as diagnostic were not sufficient to discriminate among subspecies. The pollen number and pollen:ovule (P:O) ratio varied strongly among subspecies; self-pollinated flowers produced a significantly lower number of seeds than open-pollinated flowers. Retention of empty fruits and high levels of pre-dispersal seed predation were observed in every case.

Conclusions: The variation of P:O ratios among subspecies suggests different efficiency in pollen transfer. The species is self-compatible, nevertheless all subspecies require pollen vectors to enhance cross pollination and viable seed production. Fruit retention may have evolved as a strategy to reduce predation, ensuring higher plant fitness.     

Populations evolving towards failure: costs of adaptation under competition at the range edge of an invasive perennial plant

Background: Species undergoing range expansion adapt to novel and stressful environments at range fronts. These adaptations of the edge populations may incur fitness costs. These costs may play a crucial role in stopping range expansion before absolute physiological and evolutionary limits were reached. Costs however have proven to be elusive. These may be specifically expressed under competition.

Aims: Here, we assessed the costs of adaptation in range-edge populations of an invasive plant by evaluating plant responses under competition.

Methods: We grew plants from range-centre and edge populations under competition treatments in a glasshouse. We predicted that plants from the range-edge would express lower reproductive efficiency under competition compared with centre population plants, and this would indicate a potentially maladaptive response.

Results: Under high competition, plants from the range-edge expressed lower reproductive efficiency relative to range-centre plants which supported our prediction. In addition, they were more heavily affected by competition.

Conclusions: Adaptation to novel environments at the range-edge has incurred a cost as a potentially maladaptive response under competition, which may contribute to the formation of the range-edge. This finding suggests that these costs likely form part of the classic trade-offs involved with stress-tolerance and may have effects on range evolution.     

The macroecology of animal versus wind pollination: ecological factors are more important than historical climate stability

Background: The relative frequency of wind- and animal-pollinated plants a non-randomly distributed across the globe and numerous hypotheses have been raised for the greater occurrence of wind pollination in some habitats and towards higher latitudes. To date, however, there has been no comprehensive global investigation of these hypotheses.

Aims: Investigating a range of hypotheses for the role of biotic and abiotic factors as determinants of the global variation in animal vs. wind pollination.

Methods: We analysed 67 plant communities ranging from 70º north to 34º south. For these we determined habitat type, species richness, insularity, topographic heterogeneity, current climate and late-quaternary climate change. The predictive effects of these factors on the proportion of wind- and animal-pollinated plants were tested using correlations, ordinary least squares (OLS) and logistic regression analyses with information-theoretic model selection.

Results: The proportion of animal-pollinated plant species was positively associated with plant species richness and current temperature. Furthermore, in forest, animal pollination was positively related to precipitation. Historical climate was only weakly and idiosyncratically correlated with animal pollination.

Conclusion: Results were consistent with the hypothesised reduced chance for wind-transported pollen reaching conspecific flowers in species-rich communities, fewer constraints on nectar production in warm and wet habitats, and reduced relative effectiveness of wind dispersal in humid areas. There was little evidence of a legacy of historical climate change affecting these patterns.     

The long and the short of it: long-styled florets are associated with higher outcrossing rate in Senecio vulgaris and result from delayed self-pollen germination

Background: It has been reported that some plants of the self-compatible species Senecio vulgaris produce capitula containing long-styled florets which fail to set seed when left to self-pollinate, although readily set seed when self-pollinated by hand.

Aims: To determine if production of long-styled florets is associated with higher outcrossing rate in S. vulgaris, and whether long-styles occur in non-pollinated florets, whereas short-styles are present in self-pollinated florets.

Methods: The frequency of long-styled florets was compared in the radiate and non-radiate variants of S. vulgaris, known to exhibit higher and lower outcrossing rates, respectively. In addition, style length was compared in emasculated florets that were either self-pollinated or left non-pollinated.

Results: Long-styled florets were more frequent in the higher outcrossing radiate variant. Following emasculation, long styles occurred in non-pollinated florets, while short styles were present in self-pollinated florets. The two variants did not differ in style length within the non-pollinated or within the self-pollinated floret categories.

Conclusions: A high frequency of long-styled florets is associated with higher outcrossing rate in S. vulgaris and results from delayed self-pollination and pollen germination on stigmas.     

Riboflavin as an independent and accurate biomarker for adherence in a randomized double-blind and placebo-controlled clinical trial

Background: Medication adherence is critical for success of clinical trials.

Objective: To assess oral riboflavin is an adherence marker.

Methods: Riboflavin was incorporated into active treatment and placebo pills for a clinical trial lasting for 2 years.

Results: The accuracy (area under the receiver operating curve) of urinary riboflavin was 0.91 as a binary classifier of adherence, and was similar or better than for two active study ingredients daidzein (0.92) and genistein (0.87) (all p?<?0.0001). Decreased adherence over time was similar in the two study groups.

Conclusion: Riboflavin is an accurate and useful biomarker for study pill ingestion.     

Plant functional group responses in an African tropical forest recovering from disturbance

Background: Newly protected, tropical forests recovering from logging and clearance are increasingly important targets for conservation. Recovery is typically evaluated or monitored by using a few easily identified species groups, but this may not be sufficient as unmonitored groups of equivalent ecological importance are unlikely to respond in a similar manner due to physiological or dispersal differences.

Aims: We compared four groups of plants: large trees, shrubs and saplings, herbs and ferns in a forest recovering from disturbance. We quantified the relative importance of disturbance history and local environmental conditions in determining species richness and community composition of these groups and assessed whether the groups could act as surrogate indicators for one another.

Methods: Vegetation was surveyed on a gradient of disturbance intensity and recovery time (20–60 years) in Mabira Forest, Uganda. We looked for correlations between species groups in richness or composition across sites and used constrained ordinations to identify important environmental variables.

Results: Neither species richness nor composition patterns were correlated between groups. All groups were weakly related to disturbance history; trees and shrubs were related to soil, herbs to microhabitat and ferns to microclimate.

Conclusions: No group acted as an indicator for another. The relative influence of disturbance and local environmental effects varied in the manner predicted, with disturbance stronger for trees and environment stronger for ferns.     

Water-induced stress influences the relative investment in cleistogamous and chasmogamous flowers of an invasive grass,Microstegium vimineum (Poaceae)

Background: Global climate change has the potential to shape evolutionary trajectories of invasive species via many routes, including through changes in mating systems. Many cleistogamous (CL) plants adjust investment in CL (selfed) vs. chasmogamous (CH, potentially outcrossed) progeny across environmental gradients. However, the details of such adjustments are lacking for highly invasive plant species.

Aims: We used a highly invasive grass, Microstegium vimineum, as a model for understanding how changes in water-induced stress (including potential associated changes in soil nutrient availability) might affect mating systems and thus evolutionary change in invasive species. We predicted that plants would respond to increased water-induced stress through a relative reduction in investment in CL vs. CH reproduction (i.e., a decrease in the CL:CH ratio).

Methods: Under greenhouse conditions, we measured fecundity (number of inflorescences and florets per plant) as well as relative investment in CL vs. CH florets (CL:CH ratios for number of inflorescences, florets per inflorescence, overall florets) in response to three watering treatments approximating mesic (low) to inundated (high) conditions.

Results: Plant biomass was significantly lower in high-watering treatment relative to intermediate and low treatments, indicating that the high-water condition was stressful. Contrary to expectations, stressed plants significantly increased relative investment in CL reproduction, a pattern associated with decreased inflorescence number and increased numbers of CL florets per inflorescence.

Conclusions: We conclude that changes in water-induced stress could strongly influence realised rates of outcrossing in this invasive plant, leading to mating system evolution, and altered invasiveness.     

Plant sex and phenological stage affect interactions with rhizosphere nematode communities

Background: In dioecious plants, females and males associate differently with mycorrhizal fungi, but interactions with other rhizosphere organisms are less well studied.

Aims: We investigated the effect of plant sex on rhizosphere nematode communities associated with Corema album, a dioecious shrub occurring in coastal habitats.

Methods: Rhizosphere samples were collected from males and females in three populations (150 plants), during fruiting and flowering. Nematode communities were characterised and compared between plant sexes through statistical analyses of the abundance of trophic groups, plant parasitic nematode (PPN) genera and ecological indices.

Results: Free-living nematodes showed no statistically significant differences owing to plant sex. Conversely, PPN community composition was significantly different between plant sexes during fruiting but not flowering, suggesting that physiological requirements over the annual phenological cycle of the plant influence ecological interactions with the rhizosphere.

Of the 13 PPN genera identified, the ectoparasitic Criconema and Hemicriconemellawere more abundant in the rhizosphere of males during fruiting, whereas the endoparasitic Meloidogyne associated more frequently with females, suggesting that plant host suitability is related to PPN feeding strategy.

Conclusions: It appears that interactions of individuals of different sexes of C. album with the rhizosphere nematode community vary with phenological stage, especially for PPN.     

Mutation in the beta3 subunit of Guanine nucleotide-binding protein (GNB3) gene is not associated with Type II diabetes mellitus risk: a case–control study of a North Indian population

Context: Genetics play a major role in development and pathophysiology of Type 2 diabetes mellitus (T2DM).

Objective: To asses the association of Guanine nucleotide-binding protein (GNB3) (C825T) gene's polymorphism with T2DM.

Materials and methods: A case–control study including 400 North Indians was performed using Polymerase Chain Reaction–Restriction Fragment Length Polymorphism (PCR-RFLP) approach to analyze genetic polymorphism.

Results: No significant difference was observed in genotype and allele frequencies of GNB3 gene on comparing cases with controls.

Discussion: Our study is in agreement with studies on Polish, Japanese, Hispanic-American and Danish populations who observed no significant association between GNB3 (C825T) polymorphism and T2DM.

Conclusion: GNB3 (C825T) polymorphism is not associated with T2DM.     

Fruit production along roads and footpaths in an Atlantic rain forest area

Background: Pathways (footpaths and roads) in forests are associated with edge effects, affecting forest structure and composition and associated wildlife. However, little is known about how edge effects along pathways may impact the dynamics of fruit production and their availability for frugivores.

Aim: We related pathway width as a proxy for edge effects to fruit production. Our underlying hypothesis was that pathway width would be positively related to fruit production.

Methods: We observed fruit production along three pathways of different widths – 2, 10 and 20 m wide – and in a control area of undisturbed forest in an Atlantic rain forest stand monthly over a 2-year period.

Results: The number of species and individuals-bearing fruit was higher along the wider pathways than along the narrowest pathway and in the control area. The amount of zoochorous fruits was higher in the control area than along pathways, and the widest pathway had higher non-zoochorous fruits production. Fruiting peaks occurred along pathways, while fruiting in the control area was aseasonal.

Conclusions: Pathway width is related to fruit type and its quantity and temporal availability. These effects extend towards the forest interior beyond 35 m. The presence of paths affects food resources for frugivores and thus can contribute to reconfiguring the spatio-temporal distribution of the fauna.     

Resilience,vulnerability and conservation strategies in high-mountain pine forests in the Gredos Range,central Spain

Background: High-mountain pine forests and broom communities in central Spain today have led to contrasting interpretations of their natural or human-induced origin.

Aims: We evaluated the vulnerability and resilience of high-mountain Pinus sylvestris/P. nigra forests and derived Cytisus broom scrub communities to climate and anthropogenic disturbances.

Methods: We assessed historical transitions from forest to scrub and their relation to climate and human influences, using a multi-proxy paleoenvironmental study (pollen, non-pollen palynomorphs, charcoal, magnetic susceptibility) in three mires in the Gredos Range, western Iberian Central System.

Results: High percentages of Pinus sylvestris/nigra pollen and the identification of their macro remains demonstrated that high-mountain pine forests have been present in the oromediterranean bioclimatic belt of the Gredos Range since the mid-Holocene. After that, a major human-induced decline, enhanced by climate conditions, has led to their gradual replacement by broom communities.

Conclusions: Broom communities are derived from ancient pine forests that were intensively transformed by human activities after 700 cal year BP, and largely disappeared by ca. 500 cal yr BP. Today’s landscape, dominated by broom scrub and grasslands with scattered stands of pines, shows high resilience and provides suitable refugia for a rich mountain biodiversity which deserves a further protection.     

Sleep-disordered breathing is associated with higher carboxymethyllysine level in elderly women but not elderly men in the cardiovascular health study

Context: Carboxymethyl-lysine (CML) results from oxidative stress and has been linked to cardiovascular disease.

Objective: The objective of this study is to investigate the association between sleep-disordered breathing (SDB) – a source of oxidative stress – and CML.

Materials and methods: About 1002 participants in the Cardiovascular Health Study (CHS) were studied.

Results: Women with SDB had significantly higher CML concentration compared with those without SDB (OR?=?1.63, 95%CI?=?1.03–2.58, p?=?0.04). The association was not significant among men.

Discussion: SDB was associated with CML concentration among elderly women but not men in the Cardiovascular Health Study.

Conclusion: Accumulation of CML may be an adverse health consequence of SDB     

Trolox-equivalent antioxidant capacity and composition of five alpine plant species growing at different elevations on the Qinghai–Tibetan Plateau

Background: Alpine plants on the Qinghai–Tibetan Plateau are exposed to an extremely harsh environment, namely severe cold, strong ultraviolet radiation, hypoxia and low CO₂ partial pressure. These conditions are sources of oxidative stress, which increase in severity with increasing elevation.

Aims: To examine whether antioxidant capacity and chemical composition of alpine plants change with increasing elevation.

Methods: We measured the Trolox-equivalent antioxidant capacity (TEAC) and chemical composition of five alpine plant species at 3016, 3814 and 4621 m a.s.l.

Results: With increasing elevation: (1) the TEAC increased and total phenols and tannins tended to increase in two forb and two shrub species but not in a sedge species; (2) concentrations of protein and fat increased in all five plant species; (3) polyunsaturated fatty acids (PUFA) increased and (4) mineral concentrations tended to decrease, but trends were inconsistent.

Conclusions: We conclude that with increasing elevation, TEAC and total phenols and tannins increased which we interpreted as an adaptation to higher oxidative stress; and protein and fat contents increased to support high metabolic activity. The increase in PUFA and the trend for minerals to decrease with increasing elevation require further investigation.     

Association between polymorphisms in IL21 gene and risk for sepsis

Context: Sepsis is now the leading cause of death in the noncardiovascular intensive care unit (ICU).

Objective: To investigate whether polymorphisms in IL21 gene contribute to sepsis susceptibility.

Materials and methods: Three single-nucleotide polymorphisms of IL21 (rs907715, rs2055979, rs12508721) were genotyped by TaqMan assay in patients with sepsis and control subjects.

Results: Polymorphisms rs2055979 and rs12508721 in IL21 were more frequent in sepsis patients compared to general population. But allele frequency of rs907715 was not significantly different between sepsis patients and control subjects.

Conclusion: Polymorphisms in IL21 may be associated with sepsis risk.     

H19 non-coding RNA in urine cells detects urothelial carcinoma: a pilot study

Context: Urothelial carcinoma (UC) is common and highly recurrent. Diagnosis and follow-up involve invasive cystoscopies.

Objective: To evaluate H19 RNA in urine cells as diagnostic tool for UC.

Materials and methods: RT-PCR analysis of urine samples from healthy volunteers and UC patients.

Results: H19 RNA was unequivocally detected in the urine of 90.5% of patients and 25.9% of controls. H19 copies were three orders of magnitude higher in patients. Receiver operating characteristic analysis showed an area under the curve of 0.933.

Conclusions: This pilot study shows that urinary cell H19 is a highly sensitive test for UC and pending verification could transform patient management.     

Predictors of leptin concentration and association with cardiovascular risk in patients with coronary artery disease: results from the AtheroGene study

Context: Leptin is produced in white adipose tissue, but also in human coronary atherosclerotic lesions.

Objective: The aim of this study is to assess the prognostic value of leptin in patients with proven coronary artery disease (CAD) (N?=?1907).

Methods: AtheroGene is a contemporary CAD cohort study (N?=?3229). Median follow-up time was 3.8 (Quartile 1/3 with 2.8/4.9) years.

Results: Leptin concentration was associated with a hazard ratio (HR) for the fully adjusted model of HR?=?1.32 in women but was not significant in men. The endpoint cardiovascular death and non-fatal myocardial infarction was observed in 167 patients.

Conclusion: In women with known CAD, increased leptin concentration is useful for predicting cardiovascular death and non-fatal myocardial infarction.