Secretory products of the haptoral reservoirs and peduncular glands in two species of Bravohollisia (Monogenea : Ancyrocephalidae)

Light and electron microscopy were used to characterize the structure of secretory cells and their products involved in attachment of two monogenean parasites of fish, in order to understand their role in the attachment process. In Bravohollisia rosetta and Bravohollisia gussevi, peduncular gland cells with two nuclei, granular endoplasmic reticulum, and Golgi bodies produce dual electron-dense (DED) secretory bodies with a homogenous electron-dense rind and a less electron-dense fibrillar core (oval and concave in B. rosetta and oval in B. gussevi). The DED secretory bodies are altered as they migrate from the gland cell to the haptoral reservoir, the superficial anchor grooves, and into the gill tissues. The contents of the DED secretory bodies are exocytosed into the reservoirs, fibrillar cores persisting in the matrix, some of which condense, forming highly electron-dense spherical bodies. Small, oval, electron-dense bodies occur in the grooves, while no inclusions are visible in the homogenous exudate within the gill tissues. The single tubular extension of the reservoir enters a bifurcate channel within the anchor via a concealed, crevice-like opening on one side of the anchor. The channel directs secretions into the left and the right grooves via concealed apertures. The secretions, introduced into the tissues by the anchors, probably assist in attachment. The secretions are manifested externally as net-like structures and observed in some cases to be still attached to the point of exudation, on anchors detached from the gill tissues. This suggests that despite having the anchors detached, the worms can still remain anchored to the gill tissues via these net-like structures. Based on this, it is postulated that the net-like secretions probably function as a safety line to anchor the worm during the onset of locomotion and in doing so reduce the risk of tearing host tissues.

Age and palaeoenvironmental significance of an inter-tidal peat bed at Ballywoolen, Bann estuary, Co. Londonderry.

A recently exposed inter-tidal peat bed at Ballywoolen, Bann estuary, Co. Londonderry, has yielded new information about mid-Holocene coastal environmental change in the northeast of Ireland. Pollen analytical data and wood detritus demonstrate that peat accumulation occurred in a terrestrial environment that was free from marine influence. Radiocarbon dates suggest that the peat accumulated rapidly during a period of low relative sea level subsequent to the maximum of Holocene relative sea-level rise along the north coast of Northern Ireland. The absence of marine/brackish indicator taxa at the site suggests that the tidal range was somewhat less than that at present and/or that the channel of the river was located some distance east of its present alignment. The dates indicate that the low stand lasted for at least ~0.2 ka and possibly for ~1.1 ka. Stable, woodland-dominated landscapes are indicated at both this site and neighbouring ones around ~6.4-5.3 cal ka BP. There is no evidence for large-scale aeolian sand movement or human impact on the landscape during the period of peat accumulation.

Phenotype-environment correlations in a putative whitefish adaptive radiation

1. The adaptive radiation of fishes into benthic (littoral) and pelagic (lentic) morphs in post-glaciallakes has become an important model system for speciation. Although these systems are well stud-ied, there is little evidence of the existence of morphs that have diverged to utilize resources in theremaining principal lake habitat, the profundal zone.
2. Here, we tested phenotype-environment correlations of three whitefish (Coregonus lavaretus)morphs that have radiated into littoral, pelagic and profundal niches in northern Scandinavianlakes. We hypothesized that morphs in such trimorphic systems would have a morphology adaptedto one of the principal lake habitats (littoral, pelagic or profundal niches). Most whitefish popula-tions in the study area are formed by a single (monomorphic) whitefish morph, and we furtherhypothesized that these populations should display intermediate morphotypes and niche utiliza-tion. We used a combination of traditional (stomach content, habitat use, gill raker counts) andmore recently developed (stable isotopes, geometric morphometrics) techniques to evaluate pheno-type-environment correlations in two lakes with trimorphic and two lakes with monomorphicwhitefish.
3. Distinct phenotype-environment correlations were evident for each principal niche in whitefishmorphs inhabiting trimorphic lakes. Monomorphic whitefish exploited multiple habitats, hadintermediate morphology, displayed increased variance in gillraker-counts, and relied significantlyon zooplankton, most likely due to relaxed resource competition.
4. We suggest that the ecological processes acting in the trimorphic lakes are similar to each other,and are driving the adaptive evolution of whitefish morphs, possibly leading to the formation ofnew species.

Genome-wide association study identifies variants at CLU and PICALM associated with Alzheimer's disease

We undertook a two-stage genome-wide association study (GWAS) of Alzheimer's disease (AD) involving over 16,000 individuals, the most powerful AD GWAS to date. In stage 1 (3,941 cases and 7,848 controls), we replicated the established association with the apolipoprotein E (APOE) locus (most significant SNP, rs2075650, P = 1.8 x 10(-157)) and observed genome-wide significant association with SNPs at two loci not previously associated with the disease: at the CLU (also known as APOJ) gene (rs11136000, P = 1.4 x 10(-9)) and 5. to the PICALM gene (rs3851179, P = 1.9 x 10(-8)). These associations were replicated in stage 2 (2,023 cases and 2,340 controls), producing compelling evidence for association with Alzheimer's disease in the combined dataset (rs11136000, P = 8.5 x 10(-10), odds ratio = 0.86; rs3851179, P = 1.3 x 10(-9), odds ratio = 0.86).

A Multiple Indicators Multiple Causes (MIMIC) model of Behavioural and Psychological Symptoms in Dementia (BPSD)

Introduction: Although there is evidence for distinct behavioural sub-phenotypes in Alzheimer's disease (AD), their inter-relationships and the effect of clinical variables on their expression have been little investigated.

The role of vibrational doorway states in positron annihilation with large molecules

Positron annihilation rates in many polyatomic molecular gases are anomalously high. Qualitatively, this can be explained by positron capture in vibrational Feshbach resonances, which can occur for molecules with positive positron a?nities [Gribakin, Phys. Rev. A 61 (2000) 022720]. To verify this idea quantitatively, we examine the densities of vibrational excitation spectra of alkanes. To understand the energy dependence of the annihilation rates for alkanes, we propose that positron capture is mediated by vibrational doorway states, in which positron binding is accompanied by the excitation of fundamentals.

Primitive living chitons: Morphological cladistic analysis as a model for character evaluation

Chitons are often referred to as “living fossils” in part because they are proposed as one of the earliest-diverging groups of living molluscs, but also because the gross morphology of the polyplacophoran shell has been conserved for hundreds of millions of years. As such, the analysis of evolution and radiation within polyplacophorans is of considerable interest not only for resolving the shape of pan-molluscan phylogeny but also as model organisms for the study of character evolution. This study presents a new, rigorous cladistic analysis of the morphological characters used in taxonomic descriptions for chitons in the living suborder Lepidopleurina Thiele, 1910 (the earliest-derived living group of chitons). Shell-based characters alone entirely fail to recover any recognized subdivisions within the group, which may raise serious questions about the application of fossil data (from isolated shell valves). New analysis including characters from girdle armature and gill arrangements recovers some genera within the group but also points to the lack of monophyly within the main genus Leptochiton Gray, 1847. Additional characters from molecular data and soft anatomy, used in combination, are clearly needed to resolve questions of chiton relationships. However, the data sets currently available already provide interesting insights into the analytical power of traditional morphology as well as some knowledge about the early evolution and radiation of this group.

Gross anatomy and positional homology of gills, gonopores, and nephridiopores in “basal” living chitons (Polyplacophora: Lepidopleurina)

Traditional shell characters are insufficient to differentiate taxa within the polyplacophoran order Lepidopleurida. Additional morphological character sets from soft anatomy (e.g., gamete morphology, gill arrangement, and locations of gonopores and nephidiopores) have previously been described from only a small number of taxa. This study reports for the first time, positions of the gonopores and nephridiopores for 17 species in the Lepidopleurina. The position of both types of pores on the longitudinal body axis varies within a generalized range of the posterior third of the body; however, the separation between the pores as a proportion of the specimen’s foot length varies from 3.7% to 17% in different species. Positions of pores relative to the serial gills are also variable within species, and future studies may require a new descriptive basis in order to resolve positional homology. The order Lepidopleurida occupies a critical position with respect to understanding larger-scale patterns in polyplacophoran (and molluscan) evolution.

Children with cerebral palsy: severity and trends over time

Increasingly, more very-low-birthweight infants in the developed world are now expected to survive the neonatal period than was previously the case. There are concerns that there may be a related increase in the number of infants developing severe sensorimotor impairments. Pooled data from five registers contributing to the UK Network of Cerebral Palsy Registers, Surveys and Databases were used to identify patterns of motor impairment in relation to additional impairments and to birthweight, and to assess whether prevalence of cerebral palsy (CP) by birthweight and by severity of motor impairment had changed over time. Low-birthweight infants are at greater risk of developing CP than larger-birthweight babies. The CP rate amongst children with birthweights <2500 g was significantly higher at 16 per 1000 livebirths [95% confidence interval (CI) 14.9, 16.2] than 1.2 per 1000 livebirths [95% CI 11, 1.2] for normal-birthweight children. Despite being at greater risk of developing CP, smaller-birthweight babies are proportionately less likely to develop the most severe forms of motor impairment. Of those born weighing ≥2500 g, 23% compared with 15% weighing <1000 g (P < 0.001) were in the most severely motor impaired group. Severe motor impairment is associated with higher levels of additional impairments. CP rates for each motor impairment group in the 1990s were similar to those in the late 1970s. Rates of CP among infants born below normal birthweight are high but have decreased over time. The CP rate for infants weighing 1000–1499 g at birth decreased from around 180 per 1000 livebirths in 1979 to around 50 per 1000 livebirths from the early 1990s onwards.

The health of children with cerebral palsy and stress in their parents

Aim.  This paper is a report of a study conducted to describe the health of children with cerebral palsy and investigate predictors of stress in their parents. Background.  Children with severe cerebral palsy tend to have poorer health than their able-bodied peers, and their parents are more likely to be stressed and have poorer health. Method.  A cross-sectional survey with home visits using standard questionnaires was administered to parents in 2004–05. A total of 102/199 (51%) children and parents participated. The children were compared with a normative sample. Results.  Children with cerebral palsy had poorer physical health, and 79% of parents reported that their child had moderate to severe pain. Their poorer health, in comparison with the normal sample and measured by the Child Health Questionnaire, was related to feeding problems and seizures, general health perceptions to intellectual and feeding impairment, and family activities with severe motor, intellectual and feeding impairment. Poorer psychological well-being on the hyperactivity domain of the Strengths & Difficulties Questionnaire was related to feeding difficulties, on the prosocial domain to more severe forms of all child impairments, and on the social impairment scale to intellectual impairment. Children with psychological problems had statistically significantly increased odds (OR = 7·2, 95% CIs 2·6–20·3) of having parents with high stress. Conclusion.  Children with cerebral palsy and associated impairments are at higher risk of poorer health and family well-being. A family-centred approach to the care of children with cerebral palsy and their families is essential to ensure both receive adequate care and support.

The needs of children and young people with cerebral palsy.

Because cerebral palsy (CP) is a sufficiently common condition of childhood and adolescence, the number and needs of these children and young people with cerebral palsy are monitored by centres across the UK () and Europe (). This article describes the epidemiology of CP in childhood using data derived from the Northern Ireland Cerebral Palsy Register, which is one of the longest running CP registers in Europe. The findings presented here are similar to, and representative of, the epidemiology of CP in the western world ().