Enzyme-linked immunosorbent assay. II. Quantitative assay of protein antigen, immunoglobulin G, by means of enzyme-labelled antigen and antibody-coated tubes

Alkaline phosphatase from calf intestinal mucosa has been conjugated to a protein antigen, rabbit IgG. Such conjugates, prepared by glutardialdehyde, have been used in a competitive solid phase immunoassay. In this test native antigen inhibits the binding of the conjugate to homologous antibodies adsorbed to plastic tubes. Using this assay 1-100 ng/ml of the antigen could be determined.     

Can hyperparasitoids cause large‐scale outbreaks of insect herbivores?

Synchronous population fluctuations occur in many species and have large economic impacts, but remain poorly understood. Dispersal, climate and natural enemies have been hypothesized to cause synchronous population fluctuations across large areas. For example, insect herbivores cause extensive forest defoliation and have many natural enemies, such as parasitoids, that may cause landscape‐scale changes in density. Between outbreaks, parasitoid‐caused mortality of hosts/herbivores is high, but it drops substantially during outbreak episodes. Because of their essential role in regulating herbivore populations, we need to include parasitoids in spatial modelling approaches to more effectively manage insect defoliation. However, classic host‐parasitoid population models predict parasitoid density, and parasitoid density is difficult to relate to host‐level observations of parasitoid‐caused mortality. We constructed a novel model to study how parasitoids affect insect outbreaks at the landscape scale. The model represents metacommunity dynamics, in which herbivore regulation, colonisation and extinction are driven by interactions with the forest, primary parasitoids and hyperparasitoids. The model suggests that parasitoid spatial dynamics can produce landscape‐scale outbreaks. Our results propose the testable prediction that hyperparasitoid prevalence should increase just before the onset of an outbreak because of hyperparasitoid overexploitation. If verified empirically, hyperparasitoid distribution could provide a biotic indicator that an outbreak will occur.     

DegePrime,a Program for Degenerate Primer Design for Broad-Taxonomic-Range PCR in Microbial Ecology Studies

The taxonomic composition of a microbial community can be deduced by analyzing its rRNA gene content by, e.g., high-throughput DNA sequencing or DNA chips. Such methods typically are based on PCR amplification of rRNA gene sequences using broad-taxonomic-range PCR primers. In these analyses, the use of optimal primers is crucial for achieving an unbiased representation of community composition. Here, we present the computer program DegePrime that, for each position of a multiple sequence alignment, finds a degenerate oligomer of as high coverage as possible and outputs its coverage among taxonomic divisions. We show that our novel heuristic, which we call weighted randomized combination, performs better than previously described algorithms for solving the maximum coverage degenerate primer design problem. We previously used DegePrime to design a broad-taxonomic-range primer pair that targets the bacterial V3-V4 region (341F-805R) (D. P. Herlemann, M. Labrenz, K. Jurgens, S. Bertilsson, J. J. Waniek, and A. F. Andersson, ISME J. 5:1571–1579, 2011, http://dx.doi.org/10.1038/ismej.2011.41), and here we use the program to significantly increase the coverage of a primer pair (515F-806R) widely used for Illumina-based surveys of bacterial and archaeal diversity. By comparison with shotgun metagenomics, we show that the primers give an accurate representation of microbial diversity in natural samples.     

The effects of short-term pH decrease on the reproductive output of the copepod Acartia bifilosa – a laboratory study

This laboratory study reports some reproductive responses of the copepod Acartia bifilosa to rapid variations in pH. The imposed changes mimic those that copepods could experience due to coastal upwelling, changed mixing conditions or vertical migration. We measured effects of low pH on egg production, hatching and early nauplii development (H₀: no effects on response variables between low and ambient pH). On treatment with low pH, we found positive effects on egg production rate and nauplii development time. The positive response to low pH could be an initial stress response or show that A. bifilosa is tolerant to the experimental pH values. The result suggests that A. bifilosa is adapted to pH changes as it performs daily migrations between the depths with differing pH. It could also be advantageous for population development if eggs hatch at high speed and so reduce the possibility that they will sink into anoxic and low pH waters.     

Abnormal reaction to central nervous system injury in mice lacking glial fibrillary acidic protein and vimentin

In response to injury of the central nervous system, astrocytes become reactive and express high levels of the intermediate filament (IF) proteins glial fibrillary acidic protein (GFAP), vimentin, and nestin. We have shown that astrocytes in mice deficient for both GFAP and vimentin (GFAP-/-vim-/-) cannot form IFs even when nestin is expressed and are thus devoid of IFs in their reactive state. Here, we have studied the reaction to injury in the central nervous system in GFAP-/-, vimentin-/-, or GFAP-/-vim-/- mice. Glial scar formation appeared normal after spinal cord or brain lesions in GFAP-/- or vimentin-/- mice, but was impaired in GFAP-/-vim-/- mice that developed less dense scars frequently accompanied by bleeding. These results show that GFAP and vimentin are required for proper glial scar formation in the injured central nervous system and that some degree of functional overlap exists between these IF proteins.     

A p50 surface antigen restricted to human urinary bladder carcinomas and B lymphocytes

Summary We have previously described the derivation of a monoclonal antibody, S2C6, to a novel 50 Kdalton antigen associated with human urinary bladder carcinoma. No reactions were obtained with carcinomas of unrelated origin or with normal urothelial cells. However, the antibody also reacted with a similar antigen on some cell lines of B lymphocyte origin. Using large panels of target cells we have now shown that this reactivity was entirely restricted to cells of the B lineage within the haematopoietic system. As opposed to its apparent restriction to malignant cells of the urothelium, the S2C6 antigen was expressed by normal B lymphocytes as well as by many malignant B cells (chronic lymphocytic leukaemia, hairy cell leukaemia and immunocytoma). Pre-B cells derived from acute lymphocytic leukaemia and plasma cells from multiple myeloma lacked the antigen. Expression was significantly enhanced on cultured B cells from Burkitt lymphomas and on Epstein-Barr virus-transformed lymphoblastoid cell lines including those of the pre-B phenotype derived from fetal bone marrow. As judged from the molecular size and the distribution pattern displayed by the S2C6 antigen it appears to be distinct from other B cell antigens previously described. A possible relation of the S2C6 antigen to a receptor for B cell growth factors is discussed.     

Pf155/RESA antigen is localized in dense granules of Plasmodium falciparum merozoites

Immunoelectron microscopy demonstrated the presence of Pf155/RESA in dense granules of Plasmodium falciparum merozoites rather than in micronemes as previously suggested. Since the dense granules are released after the merozoite enters the parasitophorous vacuole, the role of Pf155/RESA in invasion and subsequent steps of parasite development may differ from that of a molecule located in the micronemes.     

Plasmodium falciparum: analysis of the interaction of antigen Pf155/RESA with the erythrocyte membrane

The location of the Plasmodium falciparum vaccine candidate antigen Pf155/RESA in the membrane of infected erythrocytes was analzyed by means of selective surface radioiodination and immunofluorescence of surface-modified cells. The lack of radiolabel in Pf155/RESA as well as its localization by immunofluorescence similar to that of the N-terminal region of erythrocyte band 3 suggests that the antigen is associated with the cytoplasmic phase of the erythrocyte membrane. In concordance with this, Pf155/RESA was detected by immunofluorescence on the surface of inside out membrane vesicles from P. falciparum-infected erythrocytes. Pf155/RESA from spent culture medium also bound to inside out membrane vesicles of normal erythrocytes as well as to cytoskeletal shells of such vesicles, but failed to bind to sealed right-side out membrane vesicles. Depletion of spectrin from the vesicles abolished antigen binding, suggesting that Pf155/RESA association with the erythrocyte cytoskeleton is mediated by spectrin.