Assessment of Theileria infections in Rhipicephalus appendiculatus ticks collected from the field

Collections of adult Rhipicephalus appendiculatus ticks were made from bait cattle and vegetation at two field sites in areas of Kenya in which East Coast fever caused by Theileria parva is endemic. These ticks, together with two experimentally infected batches of ticks, were examined for infection with Theileria by four methods. Whole salivary glands were stained with methyl green pyronin or Feulgen's stain. Whole ticks were ground in medium, the suspensions were filtered and centrifuged and the treated material was examined microscopically and tested for infectivity by inoculation into cattle. All field collections and experimental batches of ticks were infected with Theileria and all four methods detected the infections. Approximately 1.5% of the ticks in the field collections were found to be infected with Theileria and the treated material from these ticks transmitted T. parva to cattle. It is considered that it will be feasible to survey field infection rates quantitatively by collecting ticks from bait cattle and vegetation for examination by a combination of salivary gland staining and preparation of tick suspensions for microscopy and infectivity tests.     

Immunologically induced generation of tetraene and pentaene leukotrienes in the peritoneal cavities of menhaden-fed rats

The generation of sulfidopeptide leukotrienes and leukotriene B (LTB) in response to an IgG-mediated immune complex reaction in the peritoneal cavities of rats fed either a menhaden oil-supplemented diet or a beef tallow-supplemented diet for 9 to 10 wk was determined with the combined techniques of radioimmunoassay (RIA) and reverse-phase high performance liquid chromatography. Rats on the fish fat diet (FFD) incorporated eicosapentaenoic acid (EPA) into pulmonary and splenic tissues with an EPA:arachidonic acid ratio of approximately 2:1, whereas rats on the beef fat diet (BFD) showed no detectable EPA. The estimated total quantities of immunoreactive sulfidopeptide leukotrienes generated by each group of rats were similar, ranging from 70 to 99 ng/ rat in the FFD groups and 65 to 109 ng/rat in the BFD groups; for rats on the FFD this total included the pentaene products LTC5, LTD5, and LTE5 in quantities ranging from 24 to 39 ng/rat. The total quantities of immunoreactive LTB generated in the two groups of rats were similar, being 6 to 29 ng LTB4/rat for the BFD groups and the sum of LTB4 and LTB5 of 8 to 36 ng/rat for the FFD groups. There was a two- to seven-fold preferential generation of immunoreactive LTB5 over LTB4 in the FFD rats. LTC5 was equipotent with LTC4 in contracting guinea pig pulmonary parenchymal strips and ileal tissues. In contrast, LTB5 was 1/30 to 1/60 as potent and did not reach the same maximum as LTB4 in eliciting neutrophil chemotaxis. The finding that FFD favors the immunologic generation of LTB5, which has attenuated biologic activity when compared to LTB4, suggests that EPA-enriched tissues may produce less pro-inflammatory activity than tissues that are EPA-poor.     

The promise of genomics in the study of plant-pollinator interactions

Flowers exist in exceedingly complex fitness landscapes, in which subtle variation in each trait can affect the pollinators, herbivores and pleiotropically linked traits in other plant tissues. A whole-genome approach to flower evolution will help our understanding of plant-pollinator interactions.     

Separation of rabbit ileum mucus secretion from electrolyte and water secretion by cholera enterotoxin, verapamil and A23187

Net water, Na+, Cl- and HCO3- fluxes were measured in in vivo rabbit ileal loops, while mucus secretion was assessed by measuring the glycoprotein or total sialic acid secreted into the lumen, or by measuring the luminal fluid viscosity. Inoculating loops with cholera enterotoxin (CT) produced a sustained secretion of electrolytes and water, but a more transient secretion of mucus. A dose of verapamil was found which, when included in the luminal fluid, inhibited or delayed the CT-induced mucus secretion while not affecting the ongoing electrolyte and water secretion. Exposure of the ileal mucosa to the ionophore, A23187, in the presence of 2mM Ca++ resulted in a brief secretion of mucus, with no change in basal water absorption. Verapamil inhibited this A23187-induced mucus secretion. The ionophore was not effective in the absence of luminal Ca++. Thus rabbit ileum mucus secretion can be separated from electrolyte and water secretion by agents that affect Ca++ movement.     

Nature of antigens and antibodies in immune complexes isolated by staphylococcal protein A from plasma of melanoma patients

Summary Immune complexes (IC) were isolated from plasma of melanoma patients by absorption to staphylococcal protein A and subsequent elution with MgCl₂. The isolated ICs were purified by precipitation with polyethylene glycol and sucrose density gradient ultracentrifugation after radioiodination with ¹²⁵I. The purified ICs were dissociated and radiolabeled antigen/antibody components were separated by ultracentrifugation at low pH (2.6). Under these conditions, about 72% radioactivity of the purified IC remained in the light-density region as a wide band. After neutralization, 26%–60% radioactivity in the region of 5S sedimentation bound to immobilized autologous immunoglobulins, as opposed to a maximum of 23% to immobilized immunoglobulins from human normal serum. Significant levels (73%–77%) of radioactivity in 7S region bound to rabbit anti-human IgG immunobeads. Immunoprecipitation of the antigen fraction by allogeneic anti-melanoma and rabbit anti-melanoma antibodies followed by SDS-polyacrylamide gel electrophoresis revealed the presence of a fetal antigen (FA) and a melanoma tumor-associated antigen (TAA). In addition, the presence of auto-antigen(s) was indicated by using autologous antibody in immunoprecipitation. Immunoglobulins (IgG) isolated from purified IC bound to cultured melanoma, sarcoma, and normal fibroblasts, although the binding to sarcoma and normal fibroblasts could be inhibited by preincubation of isolated IgG with soluble FA but not with soluble melanoma TAA. Thus, results of this investigation provide evidence that circulating IC in melanoma patients are composed of at least IgG and different antigens, and some of these antigens are produced by their tumor.     

Serum Fibrin/Fibrinogen Degradation Products Associated with Postoperative Pulmonary Embolus and Venous Thrombosis

A total of 76 “high-risk” surgical patients were studied for evidence of venous thromboembolic disease. Episodes of deep vein thrombosis and of pulmonary embolism were related to changes in blood levels of fibrin degradation products (F.D.P.). When diagnosed either by ordinary clinical means or by venography and isotope scanning significantly raised F.D.P. levels were found in all cases. Serum F.D.P. estimations are unlikely to help in detecting deep vein thrombosis, but may prove valuable in diagnosing pulmonary embolism.     

Differential impact of retrotransposon populations on the genome of allotetraploid tobacco (<Emphasis Type="Italic">Nicotiana tabacum</Emphasis>)

LTR-retrotransposons contribute substantially to the structural diversity of plant genomes. Recent models of genome evolution suggest that retrotransposon amplification is offset by removal of retrotransposon sequences, leading to a turnover of retrotransposon populations. While bursts of amplification have been documented, it is not known whether removal of retrotransposon sequences occurs continuously, or is triggered by specific stimuli over short evolutionary periods. In this work, we have characterized the evolutionary dynamics of four populations of copia-type retrotransposons in allotetraploid tobacco (Nicotiana tabacum) and its two diploid progenitors Nicotiana sylvestris and Nicotiana tomentosiformis. We have used SSAP (Sequence-Specific Amplification Polymorphism) to evaluate the contribution retrotransposons have made to the diversity of tobacco and its diploid progenitor species, to quantify the contribution each diploid progenitor has made to tobacco's retrotransposon populations, and to estimate losses or amplifications of retrotransposon sequences subsequent to tobacco's formation. Our results show that the tobacco genome derives from a turnover of retrotransposon sequences with removals concomitant with new insertions. We have detected unique behaviour specific to each retrotransposon population, with differences likely reflecting distinct evolutionary histories and activities of particular elements. Our results indicate that the retrotransposon content of a given plant species is strongly influenced by the host evolutionary history, with periods of rapid turnover of retrotransposon sequences stimulated by allopolyploidy.