Two Amino-acid Carriers in Pea Chloroplasts

CHLOROPLASTS are more permeable to amino-acids^1,2 than are cell membranes³ and also discriminate between their optical isomers². This has led to the suggestion that the passage of amino-acids through the limiting membranes of chloroplasts is facilitated by carriers². Using the additional criteria of saturation and competition, we support this suggestion and show that at least two carriers are probably involved.     

The unpredictability of favourability: condition assessment and protected areas in England

The probability that protected areas will deliver their potential for maintaining or enhancing biodiversity is likely to be maximised if they are appropriately and effectively managed. As a result, governments and conservation agencies are devoting much attention to the management of protected areas. In the U.K., the demand for performance accountability has resulted in Public Service Agreements (PSA) that set out targets for government departments to deliver results in return for investments being made. One such target for England is to ensure that all nationally important wildlife sites are in favourable condition by 2010. Here, we tested the hypothesis, of potential strategic importance, that the ecological condition of these sites is predictable from relationships with a range of physical, environmental and demographic variables. We used binary logistic regression to investigate these relationships, using the results of English Nature’s 1997–2003 condition assessment exercise. Generally, sites in unfavourable condition tend to be larger in area, located at higher elevations, but with higher human population density and are more spatially isolated from units of the same habitat. However, despite the range of different parameters included in our models, the extent to which the condition of any given site could be predicted was low. Our results have implications for the delivery of PSA targets, funding allocation, and the location of new protected areas.     

A predictive model for freshwater bioassessment (Mondego River,Portugal)

We sampled macroinvertebrates at 75 locations in the Mondego river catchment, Central Portugal, and developed a predictive model for water quality assessment of this basin, based on the Reference Condition Approach. Sampling was done from June to September 2001. Fifty-five sites were identified as “Reference sites” and 20 sites were used as “Test sites” to test the model. At each site we also measured 40 habitat variables to characterize water physics and chemistry, habitat type, land use, stream hydrology and geographic location. Macroinvertebrates were generally identified to species or genus level; a total of 207 taxa were found. By Unweighted Pair Group Method with Arithmetic mean (UPGMA) clustering and analysis of species contribution to similarities percentage (SIMPER), two groups of reference sites were established. Using Discriminant Analysis (stepwise forward), four variables correctly predicted 78% of the reference sites to the appropriate group: stream order, pool quality, substrate quality and current velocity. Test sites’ environmental quality was established from their relative distance to reference sites, in MDS ordination space, using a series of bands (BEAST methodology). The model performed well at upstream sites, but at downstream sites it was compromised by the lack of reference sites. As with the English RIVPACS predictive model, the Mondego model should be continually improved with the addition of new reference sites. The adaptation of the Mondego model methodology to the Water Framework Directive is possible and would consist mainly of the integration of the WFD typology and increasing the number of ellipses that define quality bands. Handling editor: K. Martens     

Emerging infectious diseases and animal social systems

Emerging infectious diseases threaten a wide diversity of animals, and important questions remain concerning disease emergence in socially structured populations. We developed a spatially explicit simulation model to investigate whether—and under what conditions—disease-related mortality can impact rates of pathogen spread in populations of polygynous groups. Specifically, we investigated whether pathogen-mediated dispersal (PMD) can occur when females disperse after the resident male dies from disease, thus carrying infections to new groups. We also examined the effects of incubation period and virulence, host mortality and rates of background dispersal, and we used the model to investigate the spread of the virus responsible for Ebola hemorrhagic fever, which currently is devastating African ape populations. Output was analyzed using regression trees, which enable exploration of hierarchical and non-linear relationships. Analyses revealed that the incidence of disease in single-male (polygynous) groups was significantly greater for those groups containing an average of more than six females, while the total number of infected hosts in the population was most sensitive to the number of females per group. Thus, as expected, PMD occurs in polygynous groups and its effects increase as harem size (the number of females) increases. Simulation output further indicated that population-level effects of Ebola are likely to differ among multi-male–multi-female chimpanzees and polygynous gorillas, with larger overall numbers of chimpanzees infected, but more gorilla groups becoming infected due to increased dispersal when the resident male dies. Collectively, our results highlight the importance of social system on the spread of disease in wild mammals.     

Expression of tracheal differentiated functions in serum-free hormone-supplemented medium

Most dissociated airway epithelial cells in culture express few of their in vivo functions and only to a limited degree. In this report, we demonstrate that hamster tracheal epithelial (HTE) cells cultured on a collagen gel substratum in a serum-free hormone-supplemented medium differentiate to cilia-beating and mucus-secreting cell types. The medium is Ham's F-12 supplemented with insulin, epidermal growth factor, transferrin, hydrocortisone, cholera toxin, bovine hypothalamus extract, and vitamin A. Under these culture conditions, HTE cells exhibit a growth rate of 24 h/population doubling and reach confluency, at a density of 2-5 X 10(4) cells/cm2, within 2 weeks. Both the collagen gel substratum and vitamin A of this culture system are important to the growth and differentiation of HTE cells in vitro. Evidence of HTE cell differentiation has been obtained at both the ultrastructural and the histochemical levels. In addition, a variety of biochemical studies (gel filtration, ion exchange column chromatography, enzyme digestion, nitrous acid treatment, and composition analysis) indicate the production of mucin-like glycoprotein in the HTE cultures. The levels of mucin-like glycoprotein were found to closely correlate with the histochemically quantitated levels of the mucous cell type. Kinetic studies demonstrate that HTE cells rapidly lose their differentiated features during the attachment stage of primary culture but redifferentiation occurs after the cultures reach confluency. The ability of HTE cells to grow and differentiate in this serum-free culture system in the absence of other cell types should greatly facilitate the study of mucociliary functions in vitro.     

A catalogue of <Emphasis Type="Italic">Triticum monococcum</Emphasis> genes encoding toxic and immunogenic peptides for celiac disease patients

The celiac disease (CD) is an inflammatory condition characterized by injury to the lining of the small-intestine on exposure to the gluten of wheat, barley and rye. The involvement of gluten in the CD syndrome has been studied in detail in bread wheat, where a set of “toxic” and “immunogenic” peptides has been defined. For wheat diploid species, information on CD epitopes is poor. In the present paper, we have adopted a genomic approach in order to understand the potential CD danger represented by storage proteins in diploid wheat and sequenced a sufficiently large number of cDNA clones related to storage protein genes of Triticum monococcum. Four bona fide toxic peptides and 13 immunogenic peptides were found. All the classes of storage proteins were shown to contain harmful sequences. The major conclusion is that einkorn has the full potential to induce the CD syndrome, as already evident for polyploid wheats. In addition, a complete overview of the storage protein gene arsenal in T. monococcum is provided, including a full-length HMW x-type sequence and two partial HMW y-type sequences. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Immunological studies of the relationship between the antigenic change of Ascaris oocytes and the junctional fluid of the fertilization chamber

Antigenic change on the surface of immature oocytes of Ascaris occurred during passage through the oviduct. Using immunodiffusion and immunoelectrophoretic techniques we examined the possible relationship between the antigenic change of immature oocytes and the junctional fluid (JF) which is present in the fertilization chamber. From the immunodiffusion it was found that the anti-immature oocyte serum (A-I serum) had more immunoprecipitation arcs than did the anti-mature oocyte serum (A-M serum) when reacted against the junctional fluid. This indicated that A-I serum contained more immunoglobulins that reacted with junctional fluid than did the A-M serum. This result was substantiated by using immunoelectrophoretic analysis and two dimension crossed immunoelectrophoresis. Our results suggest that during the migration toward the oviduct-uterine junction the immature oocytes might shed surface proteins into the luminal fluid. Alternatively, the membrane surface of mature oocytes may be altered by the interaction with the substances present in the junctional fluid.