Increases in salinity following a shift in hydrologic regime in a constructed wetland watershed in a post-mining oil sands landscape.

Bitumen extraction via surface mining in the Athabasca Oil Sands Region results in permanent alteration of boreal forests and wetlands. As part of their legal requirements, oil companies must reclaim disturbed landscapes into functioning ecosystems. Despite considerable work establishing upland forests, only two pilot wetland-peatland systems integrated within a watershed have been constructed to date. Peatland reclamation is challenging as it requires complete reconstruction with few guidelines or previous work in this region. Furthermore, the variable sub-humid climate and salinity of tailings materials present additional challenges. In 2012, Syncrude Canada Ltd. constructed a 52-ha pilot upland-wetland system, the Sandhill Fen Watershed, which was designed with a pump and underdrain system to provide freshwater and enhance drainage to limit salinization from underlying soft tailings materials that have elevated electrical conductivity (EC) and Na+. The objective of this research is to evaluate the hydrochemical response of a constructed wetland to variations in hydrology and water management with respect to water sources, flow pathways and major chemical transformations in the three years following commissioning. Results suggest that active water management practices in 2013 kept EC relatively low, with most wetland sites <1000 µS/cm with Na+ concentrations <250 mg/L. With limited management in 2014 and 2015, the EC increased in the wetland to >1000 µS/cm in 2014 and >2000 µS/cm in 2015. The most notable change was the emergence of several Na+ enriched zones in the margins. Here, Na+ concentrations were two to three times higher than other sites. Stable isotopes of water support that the Na+ enriched areas arise from underlying process-affected water in the tailings, providing evidence of its upward transport and seepage under a natural hydrologic regime. In future years, salinity is expected to evolve in its flow pathways and diffusion, yet the timeline and extent of these changes are uncertain.

A sensitive method for the detection of poly-A tails of mRNA using a biotin-labelled heteropolymer of dT:rA.

We have developed a highly sensitive non-radioactive in situ hybridization technique that enables us to study the production of mRNAs in tissues. As part of the validation procedure of our methods, we examined various methods of detecting poly-A RNA tails of mRNA. We have used three types of biotin-labelled probes complementary to poly-A sequences: a 25-mer poly-dT oligonucleotide, a polymer of dT, and a heteropolymer of dT:rA. All the probes had the same specificity of reactivity but the heteropolymer of dT:rA gave the strongest signals as visualized histochemically by the use of alkaline phosphatase as the detection enzyme. All the probes tested for poly-A detection showed reactivity. The poly-dT oligonucleotide showed a strength of signal comparable to published results. The biotinylated polymer of dT gave a stronger signal than that of the oligonucleotide, and the heteropolymer was the strongest of all. The strong signal seen with the heteropolymer probe is due to probe complexing during hybridization, in which additional binding between sense and antisense strands of the probe (i.e. poly-rA and poly-dT) amplifies the number of biotin molecules at the hybridization site; this strategy has been exploited by us as a means of visualizing low copy numbers of specific mRNAs.

Ultrastructure of Campylobacter jejuni in gamma-irradiated mouse jejunum.

This paper describes the ultrastructure of intracellular elongated, transitional and coccoid forms of Campylobacter jejuni, in irradiated mouse jejunum infected both in vitro and in vivo and in cultured human skin fibroblasts. Jejunum of irradiated mouse incubated for 1 hour under conditions favorable to the organisms showed minimal tissue degeneration. The intracellular organisms in this material were free cytoplasmic forms showing inner membrane degeneration, loss of cytoplasmic granules, and absence of flagella. The diameter of the coccoids was up to four times that of the elongated forms, as in plate cultures. Intracellular organisms were not found in challenged unirradiated controls, indicating that irradiation of mouse cells may be required for intracellular infection with human strains of C jejuni. In contrast, challenged human fibroblasts contained typical elongated organisms in cytoplasmic vacuoles. These findings are discussed with reference to Campylobacter strain, host resistance, and "natural" animal and human Campylobacter infections.

The development of action lines in an Australian maternal serum alphafetoprotein screening service for neural tube defects.

A retrospective study covering the period from January 1, 1980 up to June 30, 1982 was conducted, producing the first definitive normal range for maternal serum alphafetoprotein from the Royal North Shore Hospital in Sydney. The normal range established is based on and applicable to the pregnant women tested at this NSW laboratory. Maternal serum alphafetoprotein levels had been determined by radioimmunoassay for 3,182 pregnancies between 13 and 20 weeks' gestation. Five anencephalics and 2 open spina bifidas were noted in the study. Only one of these abnormalities (spina bifida) was associated with maternal serum alphafetoprotein levels within the normal range, the remainder all having elevated levels. Low false positive and false negative rates of 1.16% and 0.03% respectively were obtained in this study.

The buffy coat leukoagglutination (BCLA) test.

The clumping of leukocytes in the buffy coat of whole blood is a new approach to the leukoagglutination technique. Not only is this procedure simpler, it produces consistent replicates and the results are reproducible. One of its features is the lack of cell manipulation. Buffy coat leukoagglutination (BCLA) can be induced by the addition of a variety of antigens, lectins or allogeneic sera to small samples of whole blood. It is an indicator of both cell-mediated immune responses and humoral anti-leukocyte activity. The occurrence of two morphologically distinct types of clumping also reflects this duality of the test. There is some evidence that BCLA may be a model for in vivo events.

Phagocytosis of maternal lymphocytes by the foetal trophoblast and the immunology of pregnancy.

Immunologists have been striving to find an effective theory to explain the survival of the mammalian foetal allograft ever since the late 1950s. Embryologists had revealed that the blastocyst implants in the uterine decidua by a process involving cytolysis and phagocytosis. Brewer in 1937 had demonstrated a phagocytic property of the cytotrophoblast after implantation directed at all of the circulating blood cells. We advance the theory, supported in part by our recent studies using labelled leukocytes in pregnant mice, that the cytotrophoblast is phagocytic throughout most or all of pregnancy, and that after implantation a major source of nutrition of the embryo is phagocytosed blood cells. In particular we theorize that alloreactive lymphocytes are very likely to be phagocytosed. We also theorize that there are phagocytic foetal cells derived from the placenta in the foetus as a last line of defence against alloreactive cells from the mother. Some of the maternal lymphocytes seen in the foetus could have a surveillance function over abnormal cells arising from time to time in the foetus. Nonetheless runt disease will not occur in the embryo because of the elimination of alloreactive cells, a process which in theory can continue after the birth of the young.

The evolution of an immune system.

A model for the molecular evolution of an imune system is presented. It suggests how a system of cell surface-fixed antigen receptors, called FR, to be thought of as "primitive" but still functional antibodies, could evolve into the "modern" labile T cell and antibody system, the receptors for which may be called CER (clonal expansion receptors). Perhaps the most significant insight to be gained from the theory concerns the conclusion that the immune system of an embryo may be primed by the interaction between two types of cells with complementary surface specificities. In the first type of cell the interacting molecule is an FR molecule coded by a gene of the Major Histocompatibility Complex (MHC) which has undergone a somatic mutation; in the second type it is a CER molecule also coded by a gene which has undergone a recent somatic mutation. It is believed that this insight eliminates some of the problems experienced in understanding generation of diversity, and renders unnecessary some of the more complex hypotheses about immune networks. The mechanism of action of immune response genes is easily explained by the theory.

HLA and the genesis of autoimmune diseases.

In general, evidence of autoimmunity increase with age. The following explanations are proposed: Somatic mutations causing progressive changes in cell surfaces lead to progressive increase of antibodies which cross react with normal cell surfaces (auto-antibodies). The HLA antigens (and to a lesser extent other cell surface antigens) bind foreign molecules creating a hapten-carrier relationship which will direct the immune response to the surfaces of cells, which will most commonly be the blood and tissue leukocytes. However the HLA antigens on the surfaces of cells of some solid tissues may, for reasons intrinsic to the particular antigen and cell surface, bind haptenic material leading to an immune response directed in part against the tissue. This may be a short term event while the hapten is present, or it may continue in the absence of the hapten, directed at the carrier (cell surface) molecule alone. It may be perpetuated in some tissues (e.g. joint tissues) by the presence of immune complexes or other products of inflammation.