Immunological Reactivity of Vibrio anguillarum Sero-Subgroups O2a and O2b,and Comparison of Their Lipopolysaccharide Profiles

One hundred and twenty-nine Vibrio anguillarum serogroup O2 strains were compared by slide agglutination and Western blotting for their lipopolysaccharide (LPS) structure. The strains showed six different LPS profiles, four different reaction patterns in Western blotting, and four different kinds of reaction in slide agglutination, when both unabsorbed and absorbed anti-O2a and anti-O2b sera were used. All in all, nine different groups were detected when the combination of these three methods was applied. The two serological methods gave corresponding results for almost all strains (96%). Most of these strains (84%) belonged to sero-subgroup O2a, while 12% of the strains belonged to sero-subgroup O2b. The remaining six strains had varying reactions in the used serological methods; therefore, their sero-subgroups could not be determined. These results suggest the existence of additional sero-subgroups within serogroup O2. Received: 28 May 1996 / Accepted: 10 July 1996     

Embryonic expression of Drosophila IMP in the developing CNS and PNS

Drosophila IMP (dIMP) is related to the vertebrate RNA-binding proteins IMP1-3, ZBP1, Vg1RBP and CRD-BP, which are involved in RNA regulatory processes such as translational repression, localization and stabilization. The proteins are expressed in many fetal tissues, including the developing nervous system, and IMP up-regulation in solid tumors correlates with a high metastatic potential and poor prognosis. In this study, we used immunohistochemistry and live-imaging of an endogenous promoter-driven GFP-dIMP fusion protein to reveal the expression pattern of dIMP protein throughout embryogenesis. In the cellular blastoderm, immunoreactivity was seen in the entire cell-layer, where it was localized apically to the nucleus, and in the pole cells. Later, the GFP-dIMP fusion protein appeared in the developing central nervous system, both in the brain and in the ventral nerve cord. In the peripheral nervous system, immunoreactivity was detected in both neurons and accessory cells of chordotonal and external sensory organs.     

Effect of proline on nitrogenase activity in symbiosomes from root nodules of soybean (Glycine max L.) subjected to drought stress

Experiments were carried out to investigate if drought stressaffects the ability of bacteroids from soybean (Glycine maxL.) root nodules to utilize proline and malate to support nitrogenaseactivity. The bacteroids were isolated in sub-ambient oxygenand nitrogenase activity was measured by acetylene reduction.Nitrogenase activity supported by proline was 8-fold higherin bacteroids from drought-stressed nodules than in bacteroidsfrom control nodules. In contrast to the results with prolinethere was no significant response to drought stress in the rateof bacteroid nitrogenase activity supported by malate. The effectof drought stress on transport of proline and malate acrossthe symbiosome membrane was investigated by incubation of symbiosomesisolated in sub-ambient oxygen with radioactive tracers. Droughtstress tended to increase the rate of proline uptake relativeto a minor decrease in malate uptake into symbiosomes in responseto drought. There was no indication of a saturable camer inthe symbiosome membrane for either substrate at concentrationsin the range 0.1-2 mM. The rate of malate uptake into symbiosomeswas twice as high as the rate of proline uptake at all substratelevels tested. The protein composition of the symbiosome membranewas altered in response to drought stress and these changesmay relate .to the permeability of the symbiosome membrane. Key words: Drought stress, nitrogenase activity, proline, soybean nodules, symbiosome membrane, transport     

Estimating animal behavior and residency from movement data

We present a process‐based approach to estimate residency and behavior from uncertain and temporally correlated movement data collected with electronic tags. The estimation problem is formulated as a hidden Markov model (HMM) on a spatial grid in continuous time, which allows straightforward implementation of barriers to movement. Using the grid to explicitly resolve space, location estimation can be supplemented by or based entirely on environmental data (e.g. temperature, daylight). The HMM method can therefore analyze any type of electronic tag data. The HMM computes the joint posterior probability distribution of location and behavior at each point in time. With this, the behavioral state of the animal can be associated to regions in space, thus revealing migration corridors and residence areas. We demonstrate the inferential potential of the method by analyzing satellite‐linked archival tag data from a southern bluefin tuna Thunnus maccoyii where longitudinal coordinates inferred from daylight are supplemented by latitudinal information in recorded sea surface temperatures.     

Amino acid sequence of cytochrome c fromAspergillus niger

Cytochrome c fromAspergillus niger consists of two forms, a major one (80%) with 111 amino acid residues and a minor one (20%) with 108 residues, missing the three N-terminal residues of the major one. The primary sequence ofA. niger cytochrome c was determined by standard spinning-cup Edman degradation of purified peptides and of pairs of peptides, from which the desired sequence was readily deduced by subtraction of common sequencies. Except for the extension and some variability at the N-terminal sequence, theA. niger protein conforms well with other cytochrome c structures.     

Exocellular phosphatidylethanolamine production and multiple-metal tolerance in Pseudomonas fluorescens

Abstract Pseudomonas fluorescens appeared to circumvent the challenge imposed by millimolar amounts of metals (5 mM Al³⁺, 5 mM Fe³⁺, 2 mM Ca²⁺, 1 mM Ga³⁺ and 3 mM Zn²⁺) by the formation of phosphatidylethanolamine. This lipid moiety constituted an important organic component of an insoluble gelatinous residue in which most of the test metals were immobilized at stationary phase of growth. Ultracentrifugation and dialysis experiments showed that the metals were associated with phosphatidylethanolamine from early stages of growth. Transmission electron microscopy revealed metal rich bodies in the cytoplasm prior to their secretion in the spent fluid. These results demonstrate a role of phosphatidylethanolamine in multiple-metal homeostasis.     

MHC-I-induced apoptosis in human B-lymphoma cells is dependent on protein tyrosine and serine/threonine kinases.

In addition to providing the framework for peptide presentation, major histocompatibility complex class I (MHC-I) molecules can act as signal transducing molecules in lymphoid cells. Here we show that the mobilization of intracellular calcium, which follows crosslinking of MHC-I molecules on human B lymphoma cells, is dependent on protein tyrosine kinases and the phosphatidylinositol 3 (PI-3) kinase. Functional studies showed that MHC-I crosslinking induced almost complete inhibition of the spontaneous proliferation of the B lymphoma cells as early as 6 h post-crosslinking and apoptosis 24 h post-crosslinking. Preincubation with either protein tyrosine kinase or protein serine/threonine kinase inhibitors reduced the MHC-I-induced apoptosis to background levels, whereas inhibition of PI-3 kinase had no effect. These data demonstrate a pivotal role for protein tyrosine and serine/threonine kinases in MHC-I-mediated apoptosis in human B-cells and suggest the presence of several MHC-I signaling pathways leading to diverse effects in these cells.