Understanding the impact of species on community structure is a fundamental question in ecology. There is a growing body of evidence that suggests that both subdominant species and parasites can have ...disproportionately large effects on other organisms. Here we report those impacts for a species that is both subdominant and parasitic, the hemiparasite
Rhinanthus minor
. While the impact of parasitic angiosperms on their hosts and, to a lesser degree, coexisting plant species, has been well characterized, much less is known about their effects on higher trophic levels. We experimentally manipulated field densities of the hemiparasite
Rhinanthus minor
in a species-rich grassland, comparing the plant and invertebrate communities in plots where it was removed, present at natural densities, or present at enhanced densities. Plots with natural and enhanced densities of
R. minor
had lower plant biomass than plots without the hemiparasite, but enhanced densities almost doubled the abundance of invertebrates within the plots across all trophic levels, with effects evident in herbivores, predators, and detritivores. The hemiparasite
R. minor
, despite being a subdominant and transient component within plant communities that it inhabits, has profound effects on four different trophic levels. These effects persist beyond the life of the hemiparasite, emphasizing its role as a keystone species in grassland communities.
Parkinson’s disease (PD) is a multisystem alpha-synucleinopathic neurodegenerative disease and the most prevalent neurodegenerative disorder after Alzheimer’s disease with a high incidence rate in ...the elderly population. PD is highly multifactorial in etiology and has complex and wide-ranging pathogenic mechanisms. Environmental exposures and genetic predisposition are prominent risk factors. However, current evidence suggests that an intimate link may exist between the risk factor of sleep disturbance and PD pathogenesis. PD is characterized by the pathological hallmarks of alpha-synuclein aggregations and dopaminergic neuron degeneration in the substantia nigra. The loss of dopamine-producing neurons results in both motor and non-motor symptoms, most commonly, bradykinesia, tremor, rigidity, psychiatric disorders, sleep disorders and gastrointestinal problems. Factors that may exacerbate alpha-synuclein accumulation and dopamine neuron loss include neuroinflammation and glymphatic system impairment. Extracellular alpha-synuclein can induce an inflammatory response which can lead to neural cell death and inhibition of neurogenesis. The glymphatic system functions most optimally to remove extracellular brain solutes during sleep and therefore sleep disruption may be a crucial progression factor as well as a risk factor. This literature review interprets and analyses data from experimental and epidemiological studies to determine the recent advances in establishing a relationship between glymphatic system dysfunction, sleep disturbance, and PD pathogenesis and progression. This review addresses current limitations surrounding the ability to affirm a causal link between improved glymphatic clearance by increased sleep quality in PD prevention and management. Furthermore, this review proposes potential therapeutic approaches that could utilize the protective mechanism of sleep, to promote glymphatic clearance that therefore may reduce disease progression as well as symptom severity in PD patients.
Although cardinal imaging features for the diagnostic criteria of the Dandy-Walker phenotype have been recently defined, there is a large range of unreported malformations among these patients. The ...brainstem, in particular, deserves careful attention because malformations in this region have potentially important implications for clinical outcomes. In this article, we offer detailed information on the association of brainstem dysgenesis in a large, multicentric cohort of patients with the Dandy-Walker phenotype, defining different subtypes of involvement and their potential clinical impact.
In this established multicenter cohort of 329 patients with the Dandy-Walker phenotype, we include and retrospectively review the MR imaging studies and clinical records of 73 subjects with additional brainstem malformations. Detailed evaluation of the different patterns of brainstem involvement and their potential clinical implications, along with comparisons between posterior fossa measurements for the diagnosis of the Dandy-Walker phenotype, was performed among the different subgroups of patients with brainstem involvement.
There were 2 major forms of brainstem involvement in patients with Dandy-Walker phenotype including the following: 1) the mild form with anteroposterior disproportions of the brainstem structures "only" (57/73; 78%), most frequently with pontine hypoplasia (44/57; 77%), and 2) the severe form with patients with tegmental dysplasia with folding, bumps, and/or clefts (16/73; 22%). Patients with severe forms of brainstem malformation had significantly increased rates of massive ventriculomegaly, additional malformations involving the corpus callosum and gray matter, and interhemispheric cysts. Clinically, patients with the severe form had significantly increased rates of bulbar dysfunction, seizures, and mortality.
Additional brainstem malformations in patients with the Dandy-Walker phenotype can be divided into 2 major subgroups: mild and severe. The severe form, though less prevalent, has characteristic imaging features, including tegmental folding, bumps, and clefts, and is directly associated with a more severe clinical presentation and increased mortality.
Dynamically restructuring hydrogel networks are formed from two water‐soluble polymers by functionalization with phenylboronic acid (PBA) and salicylhydroxamic acid (SHA) moieties that interact ...through pH‐sensitive and reversible covalent crosslinks (see figure). The networks can be tuned to display a wide range of pH‐responsive properties, which can potentially be exploited for drug delivery systems in biological environments where similar acidic changes occur.
The scaling between X-ray observables and mass for galaxy clusters and groups is instrumental for cluster-based cosmology and an important probe for the thermodynamics of the intracluster gas. We ...calibrate a scaling relation between the weak lensing mass and X-ray spectroscopic temperature for 10 galaxy groups in the COSMOS field, combined with 55 higher-mass clusters from the literature. The COSMOS data includes Hubble Space Telescope imaging and redshift measurements of 46 source galaxies per arcminute super(2), enabling us to perform unique weak lensing measurements of low-mass systems. Our sample extends the mass range of the lensing calibrated M-T relation an order of magnitude lower than any previous study, resulting in a power-law slope of 1.48 super(+0.13)- sub(0.09). The slope is consistent with the self-similar model, predictions from simulations, and observations of clusters. However, X-ray observations relying on mass measurements derived under the assumption of hydrostatic equilibrium have indicated that masses at group scales are lower than expected. Both simulations and observations suggest that hydrostatic mass measurements can be biased low. Our external weak lensing masses provide the first observational support for hydrostatic mass bias at group level, showing an increasing bias with decreasing temperature and reaching a level of 30%-50% at 1 keV.
Understanding the factors that drive species population dynamics is fundamental to biology. Cyclic populations of microtine rodents have been the most intensively studied to date, yet there remains ...great uncertainty over the mechanisms determining the dynamics of most of these populations. For one such population, we present preliminary evidence for a novel mechanism by which herbivore-induced reductions in plant quality alter herbivore life-history parameters and subsequent population growth. We tested the effect of high silica levels on the population growth and individual performance of voles (Microtus agrestis) reared on their winter food plant (Deschampsia caespitosa). In sites where the vole population density was high, silica levels in D. caespitosa leaves collected several months later were also high and vole populations subsequently declined; in sites where the vole densities were low, levels of silica were low and population density increased. High silica levels in their food reduced vole body mass by 0.5% a day. We argue that silica-based defences in grasses may play a key role in driving vole population cycles.
Abstract Background When performing conservative surgery for breast cancer, breast reshaping can be a challenging procedure. Level 1 oncoplastic surgery (OPS) techniques, i.e. advancement or rotation ...of glandular flaps, should be performed when less than 20 per cent breast volume is excised. Objective A new Level 1 OPS technique is described. A wide centro-lateral glandular flap is created after extensive undermining of the skin and nipple-areolar complex, and rotated into the cavity. Discussion This rotation glandular flap is a new technique for use following a wide excision, in glandular, not fatty, breasts, and when standard closure of the cavity would not leave a satisfactory cosmetic result.
The Michigan Department of Community Health (MDCH) reported 644 laboratory positive human cases of West Nile Virus (WNV) in the 2002 outbreak in the US, of which 559 cases presented with either ...meningitis or encephalitis. The first line test utilized for diagnosis of WNV infection was the immunoglobulin M (IgM)-capture enzyme-linked immunosorbent assay (MAC-ELISA). We continued testing for WNV even during winter months of the year 2002–2003 due to the awareness of other modes of WNV transmission (blood transfusion, organ transplantation, transplacental, breast milk, and occupational) as well as concern for people traveling to endemic areas. As a result of year-round testing for WNV infections during 2002–2003, we detected WNV IgM-specific antibodies in cerebrospinal fluid (CSF) specimens from three patients persisting for 110, 141, and 199 days post acute phase infection in patients with central nervous system (CNS) disease. This is a new observation and there is no published data on the persistence of WNV IgM antibodies in CSF specimens beyond 47 days. Thus, it is important to note that the presence of WNV IgM class antibodies may not always reflect acute phase infection with this virus.
1. Silica, deposited as opaline phytoliths in the leaves of grasses, constitutes 2-5% of dry leaf mass, yet its function remains unclear. It has been proposed that silica may act as an antiherbivore ...defence by increasing the abrasiveness and reducing the digestibility of grass leaves, although there is little direct experimental evidence to support this. 2. We investigated the effects of manipulated silica levels on the abrasiveness of the leaves of five grass species. We also examined the effects of silica levels on the feeding preferences, growth performance and digestion efficiency of two folivorous insects and one phloem-feeding insect. 3. Silica addition resulted in increases to leaf abrasiveness in four of the five grass species studied. Silica addition also deterred feeding by both folivores and reduced their growth rates and digestion efficiency. 4. These effects resulted in lower pupal mass of the lepidopteron larvae Spodoptera exempta and compensatory feeding by the orthopteran, Schistocerca gregaria. In contrast, silica had no effects on the feeding preference or the population growth of the phloem feeder, Sitobion avenae. 5. Our results demonstrate that silica is an effective defence against folivorous insects, both as a feeding deterrent, possibly mediated by increased abrasiveness, and as a digestibility reducer. The effects of silica on pupal mass and development time may impact on herbivore fitness and exposure to natural enemies. 6. These results are the first demonstration of a direct effect of silica on the abrasiveness of grasses and the adverse impact of silica on herbivore preference and performance.
The application of agricultural biosolids to land is likely to increase on farms as pressures intensify to manage nutrients and carbon, especially with regard to slurry. Although much work has been ...carried out in this area, it has tended to focus on specific aspects of the application‐use cycle, without a coherent framework and notably the role of soil biology has been little studied in this context, or considered appropriately in the development and application of slurry management systems. In this review article we present a hypothesis that the configuration of the soil microbial community is determined by the history of long‐term inputs to which the community has been subjected and that the resultant configuration determines the instantaneous responses of the associated soil to the presence of slurries, and posit a set of critical questions which would effectively test this.
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