Stress Responses in Avian Embryos

The day 13–14 chicken embryo is a useful model for studieson prenatal stress responses. Free dopamine, norepinephrineand epinephrine in its plasma, amniotic and allantoic fluidrespond to a variety of stresses. The allantoic fluid also containsconjugated catecholamines and conjugated steroids. However,a blood/allantois barrier excludes free thyroid hormones andfree steroids, and insulin. On the other hand, the allantoicfluid contains at least 40 amino acids (including six excitatoryamino acids) and related compounds. Most, possibly all, componentsof the allantoic fluid are regulated at specific blood/allantoisand amnion/allantois barriers, and they respond to ethanol stressand metabolite loading differentially. The avian allantois isa depot for important metabolites and messenger substances whichseems to be controlled by as yet unidentified hormones     

SELECTING PRODUCTS FOR CATEGORY APPRAISAL STUDIES — FEWER PRODUCTS DO ALMOST AS WELL AS MANY PRODUCTS

This paper analyzes the results of different strategies for selecting test products in category appraisals. The three strategies are random selection of products from the marketplace, selection on the basis of consumer sensory data, and selection on the basis of expert panel data. All three methods generate stable results for category appraisals. The stability of the results (e.g., in terms of 'drivers of liking') increases very quickly and then levels off, suggesting that the researcher does not have to work with a particularly large number of products in a category appraisal to understand the sensory-liking dynamics.
It appears in our case, that 18 products were an appropriate number to strongly reflect results for 50 products. Researchers need to be sensitive to the variation in each category. Some categories may require more or less than this number of products to cover all the sensory ranges within the specific category.     

Analysis of segment number and enzyme variation in a centipede reveals a cryptic species, Geophilus easoni sp. nov., and raises questions about speciation

Geophilomorph centipedes provide an unusual opportunity to examine patterns of variation in segment number within extant species. (Most other arthropod species are invariant in this respect.) Recent work on several geophilomorph species has revealed latitudinal clines in segment number, but has generally not called into question the identities of the species themselves. However, analysis of a unique pattern of variation in British populations of Geophilus carpophagus Leach, coupled with other morphological and enzyme data, reveals a cryptic species, Geophilus easoni sp. nov. This species has not yet been detected on the European mainland. Four distinct hypotheses are advanced regarding the speciation event through which G. easoni arose and the phylogeographic processes that resulted in the present distributions of the two species in Britain. Further study will be necessary to test these hypotheses. In any event, G. carpophagus and G. easoni provide something that has until now been absent: a case study of the genetic differences between closely-related geophilomorph species.     

The mixed xylem sap proteome of Fusarium oxysporum-infected tomato plants

Secreted proteins are known to play decisive roles in plant–fungus interactions. To study the molecular details of the interaction between the xylem-colonizing, plant-pathogenic fungus Fusarium oxysporum and tomato, the composition of the xylem sap proteome of infected tomato plants was investigated and compared with that of healthy plants. Two-dimensional gel separation and mass spectrometry yielded peptide masses and peptide sequences of 33 different proteins. Despite the absence of complete genome sequences of either tomato or F. oxysporum , 21 proteins were identified as tomato proteins and seven as fungal proteins. Thirteen of the tomato proteins were specific for infected plants. Sixteen tomato proteins were found in xylem sap for the first time, four of which were identified based on matches to expressed sequences only. Coding sequences for new proteins from F. oxysporum were identified through either direct matching to a database sequence, matching of peptide sequences to genome or expressed sequence tag databases of other Fusarium species, or PCR with degenerate primers on cDNA derived from infected plants followed by screening of a F. oxysporum BAC library. Together, these findings provide an excellent basis for further exploration of the interaction between xylem-colonizing pathogens and their hosts.     

Avoidance of an aposematically coloured butterfly by wild birds in a tropical forest

1. Birds are considered to be the primary selective agents for warning colouration in butterflies, and select for aposematic mimicry by learning to avoid brightly coloured prey after unpleasant experiences. It has long been thought that bright colouration plays an important role in promoting the avoidance of distasteful prey by birds. 2. The hypothesis that warning colouration facilitates memorability and promotes predator avoidance was tested by means of a field experiment using distasteful model butterflies. Artificial butterflies with a Heliconius colour pattern unknown to local birds were generated using bird vision models, either coloured or achromatic, and hung in tree branches in a tropical forest. Two sequential trials were conducted at each site to test avoidance by naïve and experienced predators. 3. There was a significant reduction in predation in the second trial. Also, coloured models were attacked less than achromatic models. Specifically, coloured butterflies were attacked significantly less in the second trial, but there was no significant decrease in predation on achromatic models. 4. The present results imply an important role for colour in enhancing aversion of aposematic butterflies. It has also been demonstrated that previous experience of distasteful prey can lead to enhanced avoidance in subsequent trials, supporting mimicry theory.     

Changes in the composition of British butterfly assemblages over two decades

Changes in the abundance and distribution of individual species have been widely documented in Britain and other countries in recent decades, but little has been done to determine changes in community composition over broad geographic areas. Here, we studied species turnover in 51 butterfly assemblages in Britain since 1976, examining extinction and colonisation events together with variation in the abundances of the species. We showed that the species turnover that occurred over 20 years in Britain was associated with colonisation and extinction events and also with variability in the abundance of the species. These changes in community composition differed according to the habitat requirements of the species and their previous distributions, being more evident for habitat specialists and for southerly distributed species. Colonising species often became abundant components of the communities they joined, although this was more evident for generalist than for specialist species. The abundance of species following their arrival, increased with time since colonisation. Species turnover associated with southerly species expanding northwards is consistent with being a response to climate change. The results suggest that climate- and habitat-driven changes in the identity and abundance of species within communities are widespread, and probably ubiquitous. Similar changes are likely to be occurring in other groups of organisms that are similarly undertaking major range shifts associated with climate change.     

Population trends of breeding birds in British woodlands over a 32-year period: relationships with food, habitat use and migratory behaviour

This paper outlines population trends (with confidence intervals) for 49 species in woodland habitats in Britain as monitored by the British Trust for Ornithology's (BTO) Common Bird Census (CBC) between 1967 and 1999. Additionally, the possible causes of these population trends are investigated by relating the ecological characteristics of species to the degree of population change they have undergone over different time periods. Over the whole period, 17 species showed significant decreases in abundance and 12 species showed significant increases. Whilst population trajectories were diverse, long-distance migrants showed more negative trends than other species and the timing of the changes in their populations was related to their wintering latitude, suggesting that these species may be suffering from environmental changes in the non-breeding season. There was also support for habitat specializations being related to population changes, with species classified as scrub and understorey specialists declining on average, but this was only evident across the entire study period. Additionally, species eating seeds in summer declined and those eating vegetation and making use of the agricultural landscape matrix increased. Therefore wide-scale factors such as landscape-scale processes or processes operating outside of Britain appear to be important in addition to local habitat change, especially for long-distance migrants.     

Characterization of Genotypes of Enterocytozoon bieneusi in Immunosuppressed and Immunocompetent Patient Groups

ABSTRACT. A retrospective phylogenetic analysis was performed on isolates of Enterocytozoon bieneusi to characterize the genotypes in different patient cohorts. Fifty-seven isolates, collected from patients living in Malawi and the Netherlands, were classified by age and immune status of the hosts. Sequence analysis of the internal transcribed spacer (ITS) region identified 16 genotypes; nine have not previously been described. Genotypes K and D were most prevalent among patient groups, whereas genotype C was restricted to transplantation patients receiving immunosupressives and genotype B showed a predisposition toward patients living with HIV/AIDS. Different genotypes showed more dispersion among isolates from Malawi compared with those from the Netherlands. A constructed map estimating the genealogy of the ITS region reveals a dynamic evolutionary process between the genotypes.     

Assessing the effect of elevated carbon dioxide on soil carbon: a comparison of four meta-analyses

Soil is the largest reservoir of organic carbon (C) in the terrestrial biosphere and soil C has a relatively long mean residence time. Rising atmospheric carbon dioxide (CO₂) concentrations generally increase plant growth and C input to soil, suggesting that soil might help mitigate atmospheric CO₂ rise and global warming. But to what extent mitigation will occur is unclear. The large size of the soil C pool not only makes it a potential buffer against rising atmospheric CO₂, but also makes it difficult to measure changes amid the existing background. Meta‐analysis is one tool that can overcome the limited power of single studies. Four recent meta‐analyses addressed this issue but reached somewhat different conclusions about the effect of elevated CO₂ on soil C accumulation, especially regarding the role of nitrogen (N) inputs. Here, we assess the extent of differences between these conclusions and propose a new analysis of the data. The four meta‐analyses included different studies, derived different effect size estimates from common studies, used different weighting functions and metrics of effect size, and used different approaches to address nonindependence of effect sizes. Although all factors influenced the mean effect size estimates and subsequent inferences, the approach to independence had the largest influence. We recommend that meta‐analysts critically assess and report choices about effect size metrics and weighting functions, and criteria for study selection and independence. Such decisions need to be justified carefully because they affect the basis for inference. Our new analysis, with a combined data set, confirms that the effect of elevated CO₂ on net soil C accumulation increases with the addition of N fertilizers. Although the effect at low N inputs was not significant, statistical power to detect biogeochemically important effect sizes at low N is limited, even with meta‐analysis, suggesting the continued need for long‐term experiments.