Harvesting of Algae by Froth Flotation

A highly efficient froth flotation procedure has been developed for harvesting algae from dilute suspensions. The method does not depend upon the addition of flotants. Harvesting is carried out in a long column containing the feed solution which is aerated from below. A stable column of foam is produced and harvested from a side arm near the top of the column.

The cell concentration of the harvest is a function of pH, aeration rate, aerator porosity, feed concentration, and height of foam in the harvesting column. The economic aspects of this process seem favorable for mass harvesting of algae for food or other purposes.

     

Localization of the ca-mediated apparent ion selectivity in the cross sectional volume of soybean roots

A major portion of the calcium in a soybean root appears to be in less than 10% of the root volume. Specifically, Ca is considered to be almost entirely localized in the epidermal cell layer. This relationship was established from consideration of rates and extent of ion absorption and ion interactions during the absorption process.

Presence of calcium at the root-solution interface was associated with a change in the apparent selectivity of K over Mg by soybean roots. Accumulation of calcium by soybean roots was negligible.

     

PAURODENDRON,A RHIZOMORPHIC LYCOPOD

From middle Pennsylvanian coal balls collected in Kansas and Illinois the ligules and rhizomorph of Paurodendron have been illustrated. Assignment of Paurodendron to the Lycopsida is corroborated. Discovery of the root-bearing portion of this Carboniferous lycopod establishes a diminutive, phyletic line in the Paleozoic with rhizomorphs smaller than many species of Isoeles. Paurodendron resembles the selaginelloid line more closely than other rhizomorphic types. Anatomical comparisons of Paurodendron with roots and root-bearing structures of lycopods are made; the root-bearing and a representative leaf-bearing portion of Paurodendron fraiponti have been reconstructed. The specific diagnosis has been emended, and the three species described by Fry have been reduced to one.     

The action of hydrogen peroxide on paired pulse and long-term potentiation in the hippocampus

The action of a reactive oxygen intermediate, that is, hydrogen peroxide (H2O2) on modulation of synaptic transmission was examined in the hippocampal brain slice preparation. Microinjection of H2O2 into the apical dendritic region of the CA1 pyramidal cells produced no change in either the pattern or amplitude of paired pulse facilitation compared to saline injection (control). Long term potentiation (LTP), induced by high frequency stimulation of homosynaptic inputs, however, was blocked by microinjection of H2O2 into the dendritic tree. LTP was seen in only 2 out of 10 slices investigated when treated with H2O2 while LTP was seen in 4 out of 5 slices when saline injected. The results suggest that a reactive oxygen intermediate can selectively modify synaptic mechanisms in the hippocampus.     

Production of monoclonal antibodies against principal cells of the renal collecting duct by in vitro immunization with unsolubilized antigens

We report the production of monoclonal antibodies (MAb) by an in vitro technique which react with principal cells of the renal collecting duct. Spleen cells were directly simulated in vitro with unsolubilized antigens, i.e., by direct contact with the apical site of cultivated principal cells or by contact with cell fragments. Out of several others two antibodies, IV1 and IV2, were selected, which specifically reacted with the principal cells of the collecting duct. MAbIV1 also reacted with Type A intercalated cells, indicating the existence of a common antigen in the apical membrane of both cell types. Type B intercalated cells were consistently unreactive. All other parts of the uriniferous tubule were also unreactive. In Western blot analysis MAb IV1 showed immunoreactivity with a 40 KD and a 43 KD antigen. Our experiments demonstrate the possibility of producing antibodies against unsolubilized antigens by a simple in vitro technique. The activity of particular lymphocyte in this in vitro system is shown by the specificity of the antibodies.     

Th1 and Th2 clones differ in their response to a tolerogenic signal.

Th1 and Th2 clones specific for human gamma globulin (HGG) were compared and shown to differ in terms of the effects of tolerance induction on Ag-induced proliferation and helper activity. In developing a method to induce tolerance, splenic APC that had been pulsed with HGG and then fixed with 0.15% paraformaldehyde (HGG-FAPC) were used as a means to present Ag to the Th clones in the absence of costimulatory signals. Both Th1 and Th2 clones recognized HGG-FAPC as evidenced by their ability to proliferate to HGG-FAPC. Unlike Th2, Th1 proliferated to HGG-FAPC only in the presence of T cell-depleted allogeneic spleen cells as a source of accessory cell signals. The inability of Th1 cells to proliferate in the absence of costimulatory signals was due to Ag-specific inactivation: Th1 clones preincubated with HGG-FAPC were unable to proliferate when recultured with HGG and irradiated APC. In contrast to Th1 clones, Th2 clones showed no decrease in their Ag-induced proliferative capacity after exposure to any concentration of HGG-FAPC. However, when examined by using a second assay system, that of providing help for anti-HGG antibody production by primed B cells, Th2 preincubated with HGG-FAPC were markedly inhibited (up to 90%) in their ability to provide help. Preincubation with HGG-FAPC also inhibited the helper activity of the one Th1 clone that was found to induce a significant secondary antibody response. Taken together, the results suggest that exposure of Th1 to tolerogen in the form of HGG-pulsed fixed APC inactivates Th1 proliferative capacity, and possibly Th1 helper activity as well. Exposure of Th2 cells to a tolerogen suppresses the mechanism by which the Th2 cells provide Ag-induced B cell help, but does not inhibit the mechanism by which they proliferate to HGG. Furthermore, the results define a model that incorporates Ag processing as well as Ag presentation in the induction of tolerance in vitro.     

Linkage analysis of seven kindreds with the X-linked lymphoproliferative syndrome (XLP) confirms that the XLP locus is near DXS42 and DXS37

Summary Analysis of seven kindreds indicates that the XLP locus exhibits 1% recombination with DXS42 (lod = 17.5) and no recombination with DXS37 (lod = 13.3).