Factors influencing the fecundity of Moniliformis moniliformis (Acanthocephala): constant diet and varied dose

Aspects of the reproductive performance of Moniliformis moniliformis were investigated in rats allowed to feed ad libitum on a purified diet containing 1% (w/w) fructose as an energy source for the worms. The rats were infected with either 10, 20, 40 or 80 cystacanths each with the intention of investigating density-dependent effects on worm fecundity. The establishment of the worms in the gut was independent of dose, but survival, growth and reproductive performance generally were shown to be related to the infective dose given to the rats. The effects could not be related to the absolute numbers of worms present in the small intestine at post-mortem examination. In general, some unidentified regulatory process appeared to operate to create severe density-dependence in survival so that surviving parasites were not present in numbers expected to generate competition. Attainment of sexual maturity, growth and the production of mature eggs by worms from rats given doses of 80 cystacanths each were delayed compared with worms from rats given the other doses, but eventually the performance of the high-dose worms caught up. Worms attached more anteriorly in the small intestine grew bigger and produced more mature eggs. Possible mechanisms responsible for the observed effects are discussed.     

Long-term vegetation change in the Juncus squarrosus grassland at Moor House,northern England

Data from the long-term experiment on sheep grazing versus zero sheep grazing (i.e. in an enclosure) on the composition of the Juncus squarrosus grassland at the Moor House NNR are presented. The data have been analysed to assess change in (1) the abundance of individual species, (2) higher plant and bryophyte communities, and (3) vegetation structure. The higher plant data suggested that both the enclosed-and grazed plots were changing in the same direction, but the enclosed plot was moving much faster. The general tendency was towards a blanket bog vegetation dominated by Eriophorum vaginatum and Calluna vulgaris. Juncus squarrosus has declined very quickly in the enclosed plot, but there has also been a slower decline in the grazed one. A significant increase in Calluna vulgaris has occurred only in the enclosed plot. In contrast, the bryophyte data showed completely different successional trajectories in the two treatment plots.The vegetation structure changed markedly after release from grazing, with a decrease in phytomass, but increase in necromass in the lowest height strata. There was no noticeable change in structure over the 18 year period in the grazed plot.Particular problems found in this study were that some species either fluctuated widely in response, or changed in a curvilinear manner.     

Identification of two minor subunits in the pilus of Haemophilus influenzae.

Haemophilus influenzae type b (Hib) organisms produce pili, which mediate attachment to human cells and are multimeric structures composed of a 24-kDa subunit called pilin or HifA. Although pili from other organisms contain additional proteins accessory to pilin, no structural components other than pilin have been identified in Hib pili. Previous analysis of a Hib pilus gene cluster, however, suggested that two genes, hifD and hifE, may encode additional pilus subunits. To determine if hifD and hifE encode pilus components, the genes were overexpressed in Escherichia coli and the resulting proteins were purified and used to raise polyclonal antisera. Antisera raised against C-terminal HifD and HifE fragments reacted with H. influenzae HifD and HifE proteins, respectively, on Western immunoblots. Western immunoblot analysis of immunoprecipitated Hib pili demonstrated that HifD and HifE copurified with pili. In enzyme-linked immunosorbent assays, antisera raised against a recombinant HifE protein that contained most of the mature protein reacted more to piliated Hib than to nonpiliated Hib or to a mutant containing a hifE gene insertion. Immunoelectron microscopy confirmed that the HifE antiserum bound to pili and demonstrated that the antiserum bound predominantly to the pilus tips. These data indicate that HifD and HifE are pilus subunits. Adherence inhibition studies demonstrated that the HifE antiserum completely blocked pilus-mediated hemagglutination, suggesting that HifE mediates pilus adherence.     

The two major membrane skeletal proteins (articulins) of Euglena gracilis define a novel class of cytoskeletal proteins.

60% of the peripheral membrane skeleton of Euglena gracilis consists of equimolar amounts of two proteins (articulins) with M(r)s in SDS gels of 80 and 86 kD. To understand eventually how these proteins assemble and function in maintaining cell form and membrane integrity we have undertaken a molecular characterization of articulins. A lambda gt11 expression library constructed from Euglena gracilis mRNAs was screened with antibodies against both articulins. Two sets of cDNAs were recovered, and evidence from three independent assays confirmed that both sets encoded articulins: (a) Anti-articulin antibodies recognized a high molecular weight beta-galactosidase (beta-gal) fusion protein expressed in bacteria infected with lambda gt11 cDNA clones. (b) Antibodies generated against the bacterially expressed beta-gal fusion protein identified one or the other articulin in Western blots of Euglena proteins. These antibodies also localized to the membrane skeletal region in thin sections of Euglena. (c) Peptide maps of the beta-gal fusion protein were similar to peptide maps of Euglena articulins. From the nucleotide sequence of the two sets of cDNAs an open reading frame for each articulin was deduced. In addition to 37% amino acid identity and overall structural similarity, both articulins exhibited a long core domain consisting of over 30 12-amino acid repeats with the consensus VPVPV--V--. Homology plots comparing the same or different articulins revealed larger, less regular repeats in the core domain that coincided with predicted turns in extended beta-sheets. Outside the core domain a short hydrophobic region containing four seven-amino acid repeats (consensus: APVTYGA) was identified near the carboxy terminus of the 80-kD articulin, but near the amino terminus of the 86-kD articulin. No extensive sequence similarities were found between articulins and other protein sequences in various databanks. We conclude that the two articulins are related members of a new class of membrane cytoskeletal proteins.     

Characterization of the plasmid DNAs of Rhodopseudomonas capsulata

Presence of extrachromosomal DNa in Rhodopseudomonas capsulata strain BH9 was shown by the appearance of a satellite band in a dye-buoyant density gradient. Radioactively labelled DNA was prepared from this satellite band and examined on a 5–20% sucrose gradient. Three radioactive peaks with sedimentation coefficients of 100 S, 94 S, and 58–64 S, respectively, were consistently observed. Analysis of these sedimentation coefficients suggested that there are two species of plasmid DNA with molecular sizes of 94×10⁶ daltons (named pBH91) and 74×10⁶ daltons (named pBH92). The 58–64 S peak is attributed to open circular molecules. DNAs from each peak of the sucrose gradient were examined by electronmicroscopy, and the results agree closely with those of the sucrose gradient analysis. Reassociation kinetics of the plasmid DNA was also followed. Addition of total DNA of strain BH9 increased the renaturation rate of the plasmid DNA. It was calculated from the magnitude of the increase that approximately 10% of the BH9 total DNA may hybridize with the plasmid sequences. DNA prepared from the gene transfer agent (GTA) produced by R. capsulata increases the renaturation rate of the plasmid to the same extent as total DNA isolated from the GTA producing strain, Y262.     

Quantifying the recent expansion of native invasive rush species in a UK upland environment

Rushes, such as soft rush (Juncus effusus L.), hard rush (Juncus inflexus L.), and compact rush (Juncus conglomeratus L.) have become problem species within upland grasslands across the United Kingdom and the coastal grasslands of western Norway. Indeed, being largely unpalatable to livestock and having a vigorous reproductive ecology means that they can rapidly come to dominate swards. However, rush dominance results in a reduction in grassland biodiversity and farm productivity. Anecdotal evidence from the United Kingdom suggests that rush cover within marginal upland grasslands has increased considerably in recent decades. Yet, there is currently no published evidence to support this observation. Here, we use recent and historical Google Earth imagery to measure changes in rush frequency over a 13-year period within four survey years: 2005, 2009, 2015, and 2018. During each survey year, we quantified rush presence or absence using a series of quadrats located within 300 upland grassland plots in the West Pennine Moors, United Kingdom. Data were analysed in two stages, first, by calculating mean rush frequencies per sample year using all the available plot-year combinations (the full dataset), and second by examining differences in rush frequency using only the plots for which rush frequency data were available in every sample year (the continuous dataset). The full dataset indicated that rush frequency has increased by 82% between 2005 and 2018. Similarly, the continuous dataset suggested that rush frequency has increased by 174% over the same period, with the increases in frequency being statistically significant (p < .05) between 2005–2018 and 2009–2018. We discuss the potential drivers of rush expansion in the West Pennine Moors, the ecological and agronomic implications of grassland rush infestations, and priorities for future research.     

Release from sheep-grazing appears to put some heart back into upland vegetation: A comparison of nutritional properties of plant species in long-term grazing experiments

Rewilding or wilding is a popularised means for enhancing the conservation value of marginal land. In the British uplands, it will involve a reduction, or complete removal, of livestock grazing (sheep), based on the belief that grazing has reduced plant species diversity, the ‘Wet Desert’ hypothesis. The hope is that if livestock is removed, diversity will recover. If true, we hypothesise that the species extirpated/reduced by grazing and then recover on its removal would more nutritious compared to those that persisted. We test this hypothesis at Moor House National Nature Reserve (North-Pennines), where seven sets of paired plots were established between 1953 and 1967 to compare ungrazed/sheep-grazed vegetation. Within these plot-pairs, we compared leaf properties of seven focal species that occurred only, or were present in much greater abundance, in the absence of grazing to those of 10 common species that were common in both grazed and ungrazed vegetation. Each sample was analysed for macro-nutrients, micro-nutrients, digestibility, palatability and decomposability. We ranked the species with respect to 22 variables based on effect size derived from Generalised Linear Modelling (GLM) and compared species using a Principal Components Analysis. We also assessed changes in abundance of the focal species through time using GLMs. Our results support the ‘Wet Desert’ hypothesis, that is, that long-term sheep grazing has selectively removed/reduced species like our focal ones and on recovery, they were more nutritious (macro-nutrients, some micro-nutrients) palatable, digestible and decomposable than common species. Measured changes in abundance of the focal species suggest that their recovery will take 10–20 years in blanket bog and 60 years in high-altitude grasslands. Collectively, these results suggest that sheep grazing has brought about biotic homogenization, and its removal in (re)wilding schemes will reverse this process eventually! The ‘white woolly maggots’ have eaten at least part of the heart out of the highlands/uplands, and it will take some time for recovery.     

Common congenital anomalies: Environmental causes and prevention with folic acid containing multivitamins

Congenital anomalies, congenital defects, or birth defects are significant causes of death in infants. The most common congenital defects are congenital heart defects (CHDs) and neural tube defects (NTDs). Defects induced by genetic mutations, environmental exposure to toxins, or a combination of these effects can result in congenital malformations, leading to infant death or long‐term disabilities. These defects produce significant mortality and morbidity in the affected individuals, and families are affected emotional and financially. Also, society is impacted on many levels. Congenital anomalies may be reduced by dietary supplements of folic acid and other vitamins. Here, we review the evidence for specific roles of toxins (alcohol, cigarette smoke) in causing common severe congenital anomalies like CHDs, NTDs, and ocular defects. We also review the evidence for beneficial effects for dietary supplementation, and highlight gaps in our knowledge, where research may contribute to additional benefits of intervention that can reduce birth defects. Extensive discussion of common severe congenital anomalies (CHDs, NTDs, and ocular defects) illustrates the effects of diet on the frequency and severity of these defects. Birth Defects Research (Part C) 108:274–286, 2016. © 2016 Wiley Periodicals, Inc.     

Assessment of a large number of empirical plant species niche models by elicitation of knowledge from two national experts

Quantitative models play an increasing role in exploring the impact of global change on biodiversity. To win credibility and trust, they need validating. We show how expert knowledge can be used to assess a large number of empirical species niche models constructed for the British vascular plant and bryophyte flora. Key outcomes were (a) scored assessments of each modeled species and niche axis combination, (b) guidance on models needing further development, (c) exploration of the trade‐off between presenting more complex model summaries, which could lead to more thorough validation, versus the longer time these take to evaluate, (d) quantification of the internal consistency of expert opinion based on comparison of assessment scores made on a random subset of models evaluated by both experts. Overall, the experts assessed 39% of species and niche axis combinations to be “poor” and 61% to show a degree of reliability split between “moderate” (30%), “good” (25%), and “excellent” (6%). The two experts agreed in only 43% of cases, reaching greater consensus about poorer models and disagreeing most about models rated as better by either expert. This low agreement rate suggests that a greater number of experts is required to produce reliable assessments and to more fully understand the reasons underlying lack of consensus. While area under curve (AUC) statistics showed generally very good ability of the models to predict random hold‐out samples of the data, there was no correspondence between these and the scores given by the experts and no apparent correlation between AUC and species prevalence. Crowd‐sourcing further assessments by allowing web‐based access to model fits is an obvious next step. To this end, we developed an online application for inspecting and evaluating the fit of each niche surface to its training data.