Multimeric bivalent immunogens from recombinant tetanus toxin H<Subscript>C</Subscript> fragment,synthetic hexasaccharides,and a glycopeptide adjuvant

Using recombinant tetanus toxin H_C fragment (rTT-H_C) as carrier, we prepared multimeric bivalent immunogens featuring the synthetic hexasaccharide fragment of O-PS of Vibrio cholerae O:1, serotype Ogawa, in combination with either the synthetic hexasaccharide fragment of O-PS of Vibrio cholerae O:1, serotype Inaba, or a synthetic disaccharide tetrapeptide peptidoglycan fragment as adjuvant. The conjugation reaction was effected by squaric acid chemistry and monitored in virtually real time by SELDI-TOF MS. In this way, we could prepare well-defined immunogens with predictable carbohydrate–carrier ratio, whose molecular mass and the amount of each saccharide attached could be independently determined. The ability to prepare such neoglycoconjugates opens unprecedented possibilities for preparation of conjugate vaccines for bacterial diseases from synthetic carbohydrates.     

Effects of the removal of adherent and phagocytic cells on the spleen cell lymphoproliferative response of tumor-bearing mice

Summary Cell-mediated immunity was investigated in two BALB/c mouse tumor systems using the lymphoblastogenesis test with phytohemagglutinin as the mitogen. This lymphoproliferative response was quantitated using the Stimulation Index (SI). There was little evidence for suppressor cell activity in cell mixing experiments in which spleen cells from #51 cell-injected mice were mixed with spleen cells from normal mice. Following macrophage removal by Sephadex G-10 columns and carbonyl iron ingestion, there were no significant changes in the SI values for spleen cells from the #51 cell-injected mice. In contrast, spleen cells from mice injected with H238 cells, a herpes virus-transformed cell line, had a significantly lower SI value than that of normal mice. Suppressor cell activity was demonstrated in cell mixing experiments in which spleen cells from H238 cell-injected mice were mixed with normal spleen cells. Removal of adherent cells from spleen cells from H238 cell-injected mice by Sephadex G-10 columns restored the SI value to that of normal mice. An increased SI value was also seen after removal of phagocytic cells by carbonyl iron. These results suggested that cells with the functional properties of macrophages played an important part in the immunosuppression observed in the H238 tumor system. Comparison of the two macrophage depletion methods suggested that another cell population was also involved in the suppressive effect. Results of immunofluorescent techniques with anti-Lyt-1 and anti-Lyt-2 monoclonal antibodies show these cells to be Ly 1^–, Ly 2,3⁺ phenotypes of T-lymphocytes.     

Presymptomatic testing for Huntington's disease

Summary Presymptomatic testing for Huntington's disease (HD) is possible through the use of restriction fragment length polymorphisms (RFLPs) at the closely linked D4S10 locus. Recombination between the HD and D4S10 loci will occur in 4%–5% of meioses, and is a well-recognised complication of predictive testing. Recombination between RFLPs within the D4S10 locus is a rare event and can usually be ignored. We report a case where such an intra-locus recombination frustrated attempts to predict the chance of a high-risk individual inheriting the HD gene.     

Ethylene Binding and Action in Rice Seedlings

The existence of at least two saturable, high affinity bindingsites for ethylene is demonstrated in rice seedlings. The sitesdiffer markedly in their rates of association and dissociation.Suppression of endogenous ethylene biosynthesis leads to a significantenhancement of the [¹⁴C]ethylene binding observed. Norbornadieneinhibits ethylene binding and promotion of growth by ethylene.Carbon dioxide and hypoxia promote growth but neither affectsethylene binding. (Received June 25, 1990; Accepted August 24, 1990)     

Ultrastructure of Lycopersicon peruvianum leaf explants and streptomycin-resistant shoots on medium containing streptomycin

The effect of streptomycin on morphogenic explants of Lycopersicon peruvianum Mill. was examined microscopically at both the light and ultrastructural level. Early stages in shoot regeneration from leaf explants were distinguished as meristematic tissue at both levels. Small starch grains were observed in the plastids in this tissue but not in plastids in regenerated shoots. In the presence of streptomycin, adventitious shoot regeneration from sensitive leaf strips was inhibited. Large layered bodies were observed within the plastids of sensitive leaf tissue, suggesting the disruption of thylakoid membrane formation. Streptomycin resistant L. peruvianum lines, as well as a chlorophyll-deficient line, were also examined microscopically. The chloroplasts of newly regenerated streptomycin resistant shoots contained well developed internal membranes and conspicuous starch grains. Cells containing a mixture of resistant and sensitive plastids were not observed. The plastids in chlorophyll-deficient tissue completely lacked thylakoid membranes, although small vesicles and intraplastid bodies were seen within the stroma.Abbreviations NMU N-methyl-N-nitrosourea     

Retrieval of cryostat section for comparison of histochemistry and quantitative electron microscopy in a muscle fiber.

A method is presented that can be used to perform histochemical and morphometric analyses on the same muscle fiber. Freshly dissected fibers from medial gastrocnemius muscle of adult guinea pig were kept at a resting length and rapidly frozen. Serial frozen cross-sections were cut and reacted for myofibrillar adenosine triphosphatase and succinic dehydrogenase. The adjacent section, while still frozen, was immersed into 20 degrees C glutaraldehyde fixative to which EGTA was added to minimize artifactious contraction. The fixed section was processed for electron microscopy and the section rotated before thin sectioning to give longitudinal sections enabling study of sarcomeres. Ultrastructure was well-preserved despite slight disorganization of the contractile filaments and some vesiculation of the sarcoplasmic reticulum. The Z line width was measured and the mitochondrial volume fraction estimated by point counting morphometry from 89 fibers. The fibers with dark myofibrillar adenosine triphosphatase staining have Z widths of 547 +/- 165 A (n=69) and thoshosphatase staining have Z widths of 547 +/- 165 A (n=69) and those with light stain have 1023 +/- 113 A (n=20). The density of the succinic dehydrogenase reaction product in the fibers was divided into dark and light and the mitochondrial volume fractions were foud to be 4.3 +/- 2.1% (n=52) and 1.0 +/- 1.1% (n=37), respectively.     

Ecological and acoustic responses of bush crickets to anthropogenic and natural ecotones

Biodiversity and Conservation - Ecotones occur naturally throughout complex landscapes. Each ecotone has particular ecological conditions resulting in species-specific responses. Across...