A novel surface protein of Trichomonas vaginalis is regulated independently by low iron and contact with vaginal epithelial cells

Background  

Trichomonosis caused by Trichomonas vaginalis is the number one, non-viral sexually transmitted disease (STD) that affects more than 250 million people worldwide. Immunoglobulin A (IgA) has been implicated in resistance to mucosal infections by pathogens. No reports are available of IgA-reactive proteins and the role, if any, of this class of antibody in the control of this STD. The availability of an IgA monoclonal antibody (mAb) immunoreactive to trichomonads by whole cell (WC)-ELISA prompted us to characterize the IgA-reactive protein of T. vaginalis.     

Extreme differences in rates of molecular evolution of foraminifera revealed by comparison of ribosomal DNA sequences and the fossil record

Foraminifera have one of the best known fossil records among the unicellular eukaryotes. However, the origin and phylogenetic relationships of the extant foraminiferal lineages are poorly understood. To test the current paleontological hypotheses on evolution of foraminifera, we sequenced about 1,000 base pairs from the 3' end of the small subunit rRNA gene (SSU rDNA) in 22 species representing all major taxonomic groups. Phylogenies were derived using neighbor- joining, maximum-parsimony, and maximum-likelihood methods. All analyses confirm the monophyletic origin of foraminifera. Evolutionary relationships within foraminifera inferred from rDNA sequences, however, depend on the method of tree building and on the choice of analyzed sites. In particular, the position of planktonic foraminifera shows important variations. We have shown that these changes result from the extremely high rate of rDNA evolution in this group. By comparing the number of substitutions with the divergence times inferred from the fossil record, we have estimated that the rate of rDNA evolution in planktonic foraminifera is 50 to 100 times faster than in some benthic foraminifera. The use of the maximum-likelihood method and limitation of analyzed sites to the most conserved parts of the SSU rRNA molecule render molecular and paleontological data generally congruent.      

Finding a Place for the Commonplace: Hurricane Katrina, Communities, and Preservation Law

The aftermath of Hurricane Katrina drew attention to commonplace landscape markers that create for a community a sense of place— that connection between people and places crucial to a sense of corporate and individual identity and heritage. There is a legal context for sense of place within extant federal preservation legislation. Nevertheless, many such markers with special meanings for residents have been overlooked in federal documentation, the cornerstone of which is the National Register of Historic Places. Grassroots efforts and national media coverage have helped forge a niche for sense of place within the recovery plans and policy emerging in the affected region. However, it is unclear whether this will carry over into practice. In terms of long-term policy shifts, remedying the shortcomings highlighted by Katrina may require changes to the National Historic Preservation Act and its associated guidelines and regulations, or it may entail a new approach altogether.     

Do territorial and non‐breeding Australian Magpies Gymnorhina tibicen influence the local movements of rural birds in New Zealand?

Australian Magpies Gymnorhina tibicen sometimes attack and kill other birds in New Zealand. Here we assess how Australian Magpies influence the local distribution of other birds in New Zealand and identify the members of an Australian Magpie population that display the most agonistic acts. We conducted regular observations on six territorial breeding groups and three non‐breeding flocks of Australian Magpies for 1 year to determine (1) if other birds avoid flying or foraging close to Australian Magpies, (2) the proportion of passing birds that are attacked and (3) which social subunits of the Australian Magpie population are most aggressive. In comparison with adjacent Magpie‐free control areas, significantly fewer birds of a range of species (e.g. Common Blackbird Turdus merula, Skylark Alauda arvensis, Yellowhammer Emberiza citrinella) foraged close (i.e. ≤ 50 m) to both territorial breeding groups and non‐breeding Australian Magpie flocks; fewer birds were also recorded flying near (i.e. ≤ 50 m) territorial breeding groups but not non‐breeding flocks. Excluding Australasian Harriers (Circus approximans: see below), only 8% of birds recorded within 50 m of territorial breeding groups were observed being attacked. Attacks were most frequent when numerous birds occurred near Australian Magpies and species recorded in the highest frequencies were generally attacked most. Territorial breeding groups attacked 39% of passing Australasian Harriers. All attacks consisted of the victim being swooped at or chased; no physical contact was ever observed. Both adult male and female breeding Australian Magpies were seen attacking other birds; juveniles in breeding groups sometimes supported adults but never initiated attacks. Australian Magpies in non‐breeding flocks were not seen attacking other birds, except Australasian Harriers (attacked in 17% of appearances). Our results suggest that some birds avoid foraging and/or flying close to Australian Magpies because they are sometimes chased by breeding adults of both sexes; however, the proportion of passing birds actually attacked was small. The numerous published observations of Australian Magpie attacks are apparently biased heavily towards sensational events that are rare. Possible reasons why Australian Magpies attack other birds are discussed.     

Simulating Growth and Root-shoot Partitioning in Prairie Grasses Under Elevated Atmospheric CO2and Water Stress

We constructed a model simulating growth, shoot-root partitioning,plant nitrogen (N) concentration and total non-structural carbohydratesin perennial grasses. Carbon (C) allocation was based on theconcept of a functional balance between root and shoot growth,which responded to variable plant C and N supplies. Interactionsbetween the plant and environment were made explicit by wayof variables for soil water and soil inorganic N. The modelwas fitted to data on the growth of two species of perennialgrass subjected to elevated atmospheric CO₂and water stresstreatments. The model exhibited complex feedbacks between plantand environment, and the indirect effects of CO₂and water treatmentson soil water and soil inorganic N supplies were important ininterpreting observed plant responses. Growth was surprisinglyinsensitive to shoot-root partitioning in the model, apparentlybecause of the limited soil N supply, which weakened the expectedpositive relationship between root growth and total N uptake.Alternative models for the regulation of allocation betweenshoots and roots were objectively compared by using optimizationto find the least squares fit of each model to the data. Regulationby various combinations of C and N uptake rates, C and N substrateconcentrations, and shoot and root biomass gave nearly equivalentfits to the data, apparently because these variables were correlatedwith each other. A partitioning function that maximized growthpredicted too high a root to shoot ratio, suggesting that partitioningdid not serve to maximize growth under the conditions of theexperiment.Copyright 1998 Annals of Botany Company plant growth model, optimization, nitrogen, non-structural carbohydrates, carbon partitioning, elevated CO₂, water stress,Pascopyrum smithii,Bouteloua gracilis, photosynthetic pathway, maximal growth