Analysis of the human Ig isotype response to lactoferrin binding protein A from Neisseria meningitidis

An effective vaccine for serogroup B meningococci has yet to be developed and attention has turned to subcapsular antigens of the meningococcus as possible vaccine candidates. Iron binding proteins are being studied, with most interest focused on the transferrin binding proteins (TbpA and TbpB) and the ferric binding protein (FbpA). This study describes the purification of lactoferrin binding protein A (LbpA) from two meningococcal strains and assesses the human isotype-specific serum antibody response to these proteins in patients with proven meningococcal disease due to a range of phenotypes. Overall, fewer than 50% of sera contained IgG that recognised LbpA isolated from either strain and this antibody response was not uniform between the two proteins. There was some evidence that the antibody response varied between meningococcal phenotypes. This study demonstrates that LbpA does not induce a highly cross-reactive antibody response, indicating that it is unlikely to be an effective vaccine antigen.     

Total energy flux in a marine bioluminescent bacterium

Abstract The total heat production from luminous bacteria growing on glycerol as a sole source of carbon and energy was measured in an isothermal microcalorimeter and compared to the light emitted and growth yield. Substrate concentration was measured before and after growth to calculate the amount of substrate utilized. From these data the total energy flux was determined for Vibrio harveyi : a 25 ml culture consumed 328 micromoles of glycerol (130 cal) and produced 54 calories of heat, 76.3 cal of biomass, and 3.5 millicalories of light. Bioluminescence was then only a very small fraction (0.007%) of the total energy expended.     

High efficiency electroporation of Pseudomonas aeruginosa using frozen cell suspensions

High efficiency transformation of Pseudomonas aeruginosa was achieved using frozen cell suspensions and high voltage electroporation. We have obtained frequencies as high as 5.8 x 10(8) transformants/micrograms of plasmid DNA using PA01 strain OT684 and a buffer of 15% glycerol-1 mM MOPS. The method allows for easy and reproducible production of frozen cell suspensions for rapid transformation of P. aeruginosa.     

Dissolved organic carbon and bacterial populations in the gelatinous surface microlayer of a Norwegian fjord mesocosm

The sea surface microlayer is the interfacial boundary layer between the marine environment and the troposphere. Surface microlayer samples were collected during a fjord mesocosm experiment to study microbial assemblage dynamics within the surface microlayer during a phytoplankton bloom. Transparent exopolymer particles were significantly enriched in the microlayer samples, supporting the concept of a gelatinous surface film. Dissolved organic carbon and bacterial cell numbers (determined by flow cytometry) were weakly enriched in the microlayer samples. However, the numbers of Bacteria 16S rRNA genes (determined by quantitative real-time PCR) were more variable, probably due to variable numbers of bacterial cells attached to particles. The enrichment of transparent exopolymer particles in the microlayer and the subsequent production of a gelatinous biofilm have implications on air–sea gas transfer and the partitioning of organic carbon in surface waters.     

Examination of the role of the proteolytically-activated form of protein kinase C in the differentiation of human haemopoietic cells

Abstract. In neutrophils, the phorbol ester 12- O -tetrade-canoylphorbol-l3-acetate (TPA) induced the translocation of the Ca⁺⁺- and phospholipid-dependent protein kinase, protein kinase C (PK-C) from the soluble to the particulate fraction. At the same time there was a corresponding increase in the amount of Ca⁺⁺- and phospholipid-independent protein kinase activity recovered in the soluble fraction. This soluble Ca⁺⁺- and phospholipid-independent protein kinase presumably reflects proteolytic activation of the particulate associated PK-C. Bone marrow and undifferentiated HL-60 cells also translocated PK-C to the particulate fraction in response to TPA but did not accumulate the soluble Ca⁺⁺- and phospholipid-independent form of the enzyme. Similar results were obtained using HL-60 cells induced to differentiate with dimethyl sulphoxide (DMSO), recombinant human granulocyte-macrophage colony-stimulating factor (rh GM-CSF) or la,25-dihydroxyvitamin D₃. There was also no significant change in either the number or time of expression of differentiation-specific cell surface antigens observed on HL-60 cells induced to differentiate with either DMSO, 1α,25-dihydroxyvitamin D3 or TPA in the presence of cyclosporin A, an agent reported to inhibit the proteolytic breakdown of PK-C to the Ca⁺⁺- and phospholipid-independent form. Likewise, cyclosporin A did not affect the rate or extent of differentiation of primary bone marrow cell cultures. These results suggest that the proteolytically activated and phospholipid-independent form of PK-C is probably not involved in haemopoietic cell differentiation.     

An examination of amphibian sensitivity to environmental contaminants: are amphibians poor canaries?

Nearly two decades ago, the global biodiversity crisis was catapulted to the front pages of newspapers with the recognition of worldwide amphibian declines. Amphibians earned their appellation, 'canaries in a coal mine', because of apparent high sensitivity to human-mediated environmental change. The most frequently cited causes for high susceptibility include permeable skin, a dual aquatic-terrestrial life cycle and a relatively rudimentary immune system. While some researchers have questioned the basis for the canary assertion, there has been no systematic evaluation of amphibian sensitivity to environmental challenges relative to other taxa. Here, we apply a database representing thousands of toxicity tests to compare the responses of amphibians relative to that of other taxonomic groups. The use of standardized methods combined with large numbers of identical challenges enables a particularly powerful test of relative effect size. Overall, we found that amphibians only exhibit moderate relative responses to water-borne toxins. Our findings imply that, as far as chemical contaminants are concerned, amphibians are not particularly sensitive and might more aptly be described as 'miners in a coal mine'. To the extent that amphibian declines have been mediated by chemical contaminants, our findings suggest that population losses and extinctions may have already occurred in a variety of taxa much more sensitive than amphibians.
Ecology Letters (2010) 13: 60–67     

Cytokinin induces the developmentally restricted synthesis of an extracellular protein in Physcomitrella patens

Early development of the moss Physcomitrella patens follows a simple course leading to the formation of a filamentous protonema containing only two cell-types, chloronema and caulonema. The addition of the hormone cytokinin leads to the induction of multicellular buds from such protonema. The spectrum of extracellular proteins (ECPs) synthesized by P. patens has been investigated at defined stages of development and under defined hormone treatments. It is found that in contrast to the limited changes in intracellular protein synthesis detectable, in the extracellular environment major and specific changes in the patterns of proteins synthesized occur. For example, the presence of caulonema cells is characterized by the synthesis of a 25 kDa ECP whereas early chloronema differentiation is distinguished by the presence of a 38 kDa ECP. The analysis of the pattern of ECPs synthesized by developmental mutants altered in bud formation, and in response to cytokinin in tunicamycin treated protonema (in which bud induction is blocked) indicate that the synthesis of a 14 kDa ECP is specifically induced by cytokinin. This protein represents a novel cytokinin-induced ECP. These data show that the differentiation of particular cell types in plants is associated with the synthesis of particular ECPs, and suggest that hormones which induce specific morphogenic events may do so via the synthesis of specific ECPs.