Dampening prey cycle overrides the impact of climate change on predator population dynamics : a long-term demographic study on tawny owls

Funded by ERA-Net BiodivERsA NERC. Grant Numbers: NE/E010660/1, NE/F021402/1, NE/G002045/1Peer reviewedPublisher PD

Interspecific competition affects early growth of a Eucalyptus grandis x E. camaldulensis hybrid clone in Zululand, South Africa

To determine the effects of the onset and development of vegetation competition on tree performance, a Eucalyptus hybrid clone (GC304) was planted in a field trial in Zululand, South Africa. Nine vegetation management treatments, imposed from planting, included a weedy control treatment, a manually weeded treatment, a chemically weeded treatment (glyphosate), a 1.2m row and a 1.2m inter-row weeding, a 0.5m radius ring weeding, a complete weeding except for a 0.5m radius ring around the tree (no ring weeding), and the use of two legume cover-crops, Mucuna puriens (L.) DC. (velvet bean) and Vigna unguiculata (L.) Walp. (cowpea). The different treatments applied during establishment resulted in the differential growth of the trees as determined by measurements of tree height and crown diameter. This occurred from as early as 60 days after planting. The degree of competition could be directly related to the type of vegetation (cover-crops or naturally occurring weeds) and its proximity to the tree. The predominant vegetation on this site, yellow nutsedge (Cyperus esculentus L.), was able to colonise the site rapidly, causing severe and early competition. There were strong indications that this initial competition was mainly for moisture and possibly also for nutrients, rather than competition for light. Initially, trees in those treatments that had vegetation within their immediate vicinity were most affected (weedy control, inter-row weeding and no ring weeding). With time, tree performance was more closely related to an increase in the percentage of the area kept free of vegetation. At 180 days after planting the ranking of the top five treatments in relation to the area kept free of vegetation was: manually weeded treatment (100% of area free of vegetation) > chemically weeded treatment (100% of area free of vegetation) > no ring weeding (90% of area free of vegetation) > row weeding (40% of area free of vegetation) > ring weeding (10% of area free of vegetation). The planting of cover-crops, although beneficial in terms of the suppression of competing vegetation, also caused significant tree suppression. This occurred despite the fact that their initial biomass accumulation was slower than that of the natural weed population. Of the two covercrops, the use of a velvet bean cover-crop was not considered suitable due to its vigorous vining habit which adversely affected growth form

Immune genes undergo more adaptive evolution than non-immune system genes in Daphnia pulex

<p>Abstract</p> <p>Background</p> <p>Understanding which parts of the genome have been most influenced by adaptive evolution remains an unsolved puzzle. Some evidence suggests that selection has the greatest impact on regions of the genome that interact with other evolving genomes, including loci that are involved in host-parasite co-evolutionary processes. In this study, we used a population genetic approach to test this hypothesis by comparing DNA sequences of 30 putative immune system genes in the crustacean <it>Daphnia pulex</it> with 24 non-immune system genes.</p> <p>Results</p> <p>In support of the hypothesis, results from a multilocus extension of the McDonald-Kreitman (MK) test indicate that immune system genes as a class have experienced more adaptive evolution than non-immune system genes. However, not all immune system genes show evidence of adaptive evolution. Additionally, we apply single locus MK tests and calculate population genetic parameters at all loci in order to characterize the mode of selection (directional versus balancing) in the genes that show the greatest deviation from neutral evolution.</p> <p>Conclusions</p> <p>Our data are consistent with the hypothesis that immune system genes undergo more adaptive evolution than non-immune system genes, possibly as a result of host-parasite arms races. The results of these analyses highlight several candidate loci undergoing adaptive evolution that could be targeted in future studies.</p

The reaction of Escherichia coli cytochrome bo with H202: Evidence for the formation of an oxyferryl species by two distinct routes

AbstractWe have re-examined the reaction of fast oxidised cytochrome bo with H2O2 in a stopped-flow spectrophotometer. Monitoring the reaction at 582 nm allows us to observe the formation and decay of a spectroscopically distinct intermediate which accumulates transiently prior to the formation of an oxyferryl species previously characterised in this laboratory (Watmough, N.J., Cheesman, M.R., Greenwood, C. and Thomson, A.J. (1994) Biochem. J. 300, 469–475 [1]). The reaction shows three distinct phases of which the fast and intermediate phases are bimolecular and show a marked pH dependence. Initially these results appeared incompatible with the report that only one equivalent of H2O2 is required to generate the oxyferryl species (Moody, A.J. and Rich, P.R. (1994) Eur. J. Biochem. 226, 731–737 [2]). However, these data can be reconciled by a branched reaction mechanism whose contributions differ according to the peroxide concentration used

Risk of myocardial infarction and stroke after acute infection or vaccination.

BACKGROUND: There is evidence that chronic inflammation may promote atherosclerotic disease. We tested the hypothesis that acute infection and vaccination increase the short-term risk of vascular events. METHODS: We undertook within-person comparisons, using the case-series method, to study the risks of myocardial infarction and stroke after common vaccinations and naturally occurring infections. The study was based on the United Kingdom General Practice Research Database, which contains computerized medical records of more than 5 million patients. RESULTS: A total of 20,486 persons with a first myocardial infarction and 19,063 persons with a first stroke who received influenza vaccine were included in the analysis. There was no increase in the risk of myocardial infarction or stroke in the period after influenza, tetanus, or pneumococcal vaccination. However, the risks of both events were substantially higher after a diagnosis of systemic respiratory tract infection and were highest during the first three days (incidence ratio for myocardial infarction, 4.95; 95 percent confidence interval, 4.43 to 5.53; incidence ratio for stroke, 3.19; 95 percent confidence interval, 2.81 to 3.62). The risks then gradually fell during the following weeks. The risks were raised significantly but to a lesser degree after a diagnosis of urinary tract infection. The findings for recurrent myocardial infarctions and stroke were similar to those for first events. CONCLUSIONS: Our findings provide support for the concept that acute infections are associated with a transient increase in the risk of vascular events. By contrast, influenza, tetanus, and pneumococcal vaccinations do not produce a detectable increase in the risk of vascular events

The Initial Configuration of Young Stellar Clusters: A K-band Number Counts Analysis of the Surface Density of Stars

We present an analysis of K-band stellar distributions for the young stellar clusters GGD 12-15, IRAS 20050+2720, and NGC 7129. We find that the two deeply embedded clusters, GGD 12-15 and IRAS 20050+2720, are not azimuthally symmetric and show a high degree of structure which traces filamentary structure observed in 850 micron emission maps. In contrast, the NGC 7129 cluster is circularly symmetric, less dense, and anti-correlated to 850 micron emission, suggesting recent gas expulsion and dynamical expansion have occured. We estimate stellar volume densities from nearest neighbor distances, and discuss the impact of these densities on the evolution of circumstellar disks and protostellar envelopes in these regions.Comment: 44 pages, 26 figures, Accepted to ApJ. Changes include extinction mapping, Monte Carlo field star modeling, and Nyquist sampled azimuthal stellar distributions. A version with full resolution figures is available at http://astro.pas.rochester.edu/~rguter/preprints/gutermuth_sd.tar.g

The Dscam homologue of the crustacean Daphnia is diversified by alternative splicing like in insects

In insects, the homologue of the Down syndrome cell adhesion molecule (Dscam) is a unique case of a single-locus gene whose expression has extensive somatic diversification in both the nervous and immune systems. How this situation evolved is best understood through comparative studies. We describe structural, expression, and evolutionary aspects of a Dscam homolog in 2 species of the crustacean Daphnia. The Dscam of Daphnia generates up to 13,000 different transcripts by the alternative splicing of variable exons. This extends the taxonomic range of a highly diversified Dscam beyond the insects. Additionally, we have identified 4 alternative forms of the cytoplasmic tail that generate isoforms with or without inhibitory or activating immunoreceptor tyrosine-based motifs (ITIM and ITAM respectively), something not previously reported in insect's Dscam. In Daphnia, we detected exon usage variability in both the brain and hemocytes ( the effector cells of immunity), suggesting that Dscam plays a role in the nervous and immune systems of crustaceans, as it does in insects. Phylogenetic analysis shows a high degree of amino acid conservation between Daphnia and insects except in the alternative exons, which diverge greatly between these taxa. Our analysis shows that the variable exons diverged before the split of the 2 Daphnia species and is in agreement with the nearest-neighbor model for the evolution of the alternative exons. The genealogy of the Dscam gene family from vertebrates and invertebrates confirmed that the highly diversified form of the gene evolved from a nondiversified form before the split of insects and crustaceans

Patient-reported outcome measures for acne: a mixed-methods validation study (acne PROMs).

OBJECTIVES: To examine the acceptability and validity of two patient-reported outcome measures (PROMs) for adult acne, comparing them to the validated Acne-specific Quality of Life (Acne-QoL) measure. DESIGN: Mixed-methods validation study. SETTING: Participants were recruited by (1) mail-out through primary care if they had ever consulted for acne and received a prescription for acne treatment within the last 6 months, (2) opportunistically in secondary care and (3) poster advertisement in community venues. PARTICIPANTS: 221 (204 quantitative and 17 qualitative) participants with acne, aged 18-50 years. OUTCOME MEASURES: Quantitative sub-study participants completed Acne-QoL, Skindex-16 and Comprehensive Acne Quality of Life Scale (CompAQ) at baseline, 24 hours and 6 weeks. Qualitative sub-study participants took part in cognitive think-aloud interviews, while completing the same measures. Transcribed audio recordings were analysed using inductive thematic analysis. RESULTS: Quantitative analyses suggested high internal consistency (Cronbach's alpha 0.74-0.96) and reliability (intraclass correlation coefficient values 0.88-0.97) for both questionnaires. Both scales showed floor effects on some subdomains. Skindex-16 and CompAQ showed good evidence of construct validity when compared with Acne-QoL with Spearman's correlation coefficients 0.54-0.81, and good repeatability over 24 hours.Qualitative data uncovered wide-ranging views regarding usability and acceptability. Interviewees held strong but differing views about layout, question/response wording, redundant/similar questions and guidance notes. Similarly, interviewees differed in perceptions of acceptability of the different scales, particularly on relatability of questions and emotive reactions to scales. CONCLUSIONS: All PROMs performed well in statistical analyses. No PROM showed superior usability and acceptability in the qualitative study. Any PROM should be acceptable for further research in adult acne but researchers should consider the different domains and whether they will measure only facial or facial and trunk acne before making a selection. A new PROM or further evaluation of novel PROMs may be beneficial