Role of spatial and environmental factors in shaping the rotifer metacommunity in anthropogenic water bodies

In spatially heterogeneous habitats, local communities may be shaped by both local biotic and abiotic factors and by regional factors (dispersal of individuals among habitats). In recent years, ecologists have been increasingly interested in measuring how much the structure of local communities is explained by spatial variables and by non-spatial environmental variables. We analysed the effects of biotic and abiotic factors on rotifer communities in 12 anthropogenic water bodies in the Silesian Upland. The studies were conducted in two groups of water bodies which were of differing dimensions: group A — seven water bodies situated very close to each other (between 50 and 500 m), group B — the water bodies from group A as well as 5 other water bodies situated 2 km away, which were at greater distances from each other (about 1–3 km). Apart from this, genetic variation was assessed in 3 populations of Brachionus plicatilis Müller to estimate the level of gene flow between them. A characteristic feature of anthropogenic water bodies is a high variation in environmental conditions, so they are specific and difficult habitats for many organisms. Our study shows that environmental factors played a major role in shaping the local rotifer communities in heterogeneous anthropogenic water bodies with respect to salinity. Results of this study suggest, however, that in neighbouring water bodies, dispersal is very important for maintenance of local species diversity. A medium level of genetic variation between populations of B. plicatilis indicates that gene flow occurs irrespective of the distance between local populations.     

Interferon-gamma-treated K562 target cells distinguish functional NK cells from lymphokine-activated killer (LAK) cells

In vitro incubation of the erythroleukemic cell line K562 with interferon-gamma (IFN-gamma) renders these cells relatively resistant to natural killer (NK) cell lysis. However, such treatment does not alter their sensitivity to LAK cell lysis. Thus, the lytic susceptibility of interferon-gamma-treated K562 (I-K562) cells to LAK cells as opposed to its relative resistance to NK cell lysis provides a functional assay to help distinguish these two types of effector cells. The relative resistance of I-K562 for NK cell-mediated lysis was not secondary to the release of soluble factors or the frequency of Leu-19+, CD3+ T cells, residual IFN-gamma, or expression of MHC Class I molecules. Coincubation of I-K562 cells with NK or LAK cells overnight did not appreciably change the pattern of lytic responses against K562 and I-K562 target cells. However, incubation of PBMC in vitro with I-K562 but not native K562 in the presence of r-IL-2 leads to a marked decrease in the generation of LAK cells. The inhibition of LAK cell generation was not secondary to differences in the consumption of bioactive levels of IL-2. Differences in the lytic capability of NK and LAK effector cells suggest heterogeneity among cells that mediate such non-MHC-restricted lysis. Use was made of cells from a patient with a large granular lymphocyte lymphoproliferative disease (greater than 85% Leu-19+) to determine if such cells could be used to distinguish clonal population of cells which would represent NK or LAK cell function. Of interest was the finding that such cells, even after incubation in vitro with IL-2, showed lytic function representative of NK cells but not LAK cells. Data concerning the inhibition of LAK cell generation by I-K562 cells have important implications for future therapeutic trials of IFN-gamma and IL-2 in the treatment of human malignancies.     

Characterization of lymphocyte responsiveness in early experimental syphilis. I. In vitro response to mitogens and Treponema pallidum antigens

Lymphoid cells from spleens and lymph nodes of rabbits infected with T. pallidum respond by proliferation to concanavalin A (Con A) and T. pallidum antigens. Spleen cell responsiveness to treponemal antigens appears 6 days after infection, is 100 to 600 fold higher than the response of uninfected control rabbits, and is maintained throughout the 31-day observation period. Specifically responding cells in the inguinal and popliteal lymph nodes of infected animals are demonstrable on day 10, and the magnitude of the response increases throughout the observation period. Specific responsiveness to T. pallidum antigens in vitro is enhanced in purified T cell populations and is abolished by treatment with goat anti-rabbit thymocyte serum and complement. The response of spleen and lymph node cells to Con A is unaffected during syphilitic infection. These results are consistent with a role for T cell-mediated specific immunity to treponemal antigens early after infection and do not support a hypothesis of depressed cellular immunity during syphilitic infection.     

Isolation and identification of the gibberellins of Cucumis sativus and Cucumis melo

Summary Thin-layer chromatography, gas-liquid chromatography, and mass spectrometry were used to identify gibberellins isolated from mature seeds of both Cucumis sativus (cucumber) and Cucumis melo (muskmelon). The gibberellins were extracted and purified by organic solvent fractionation, paper and thin-layer chromatography, and crystallization. Seeds of C. sativus were found to contain gibberellins A₁, A₃, A₄, and A₇ with A₁ the predominant species. Seeds of C. melo contained gibberellins A₁ and A₃ and a trace of A₅. Direct probe mass spectrometry of the gibberellins proved successful for identification purposes. Distinctive molecular ions and fragmentation patterns were obtained for each gibberellin.Journal Article No. 5664 from the Michigan Agricultural Experiment Station. This work was supported in part by a grant from the Herman Frasch Foundation.Portions were taken from a thesis submitted in partial fulfillment of the requirements for the Ph.D. degree, Michigan State University, 1971     

Structural differences in the subfragment 1 and rod portions of myosin isozymes from adult and developing rat skeletal muscles

During development of fast contracting skeletal muscle in the rat hindleg, embryonic and neonatal forms of the myosin heavy chain are present prior to the accumulation of the adult fast type ( Whalen , R. G., Sell, S. M., Butler-Browne, G.S., Schwartz, K., Bouveret, P., and Pinset -H arstr ?m, I. (1981) Nature (Lond.) 292, 805-809). Polypeptide mapping of the heavy chain subunit using partial proteolysis in the presence of sodium dodecyl sulfate has shown differences in the cleavage patterns for these various heavy chains. Using this technique, we have now examined subfragments, which represent functional domains, from several different myosin isozymes. The heavy chains of the S-1 subfragments containing either light chain 1 or light chain 3 are indistinguishable for the neonatal or fast myosin isozymes. We also isolated the S-1 fragments and the alpha-helical COOH-terminal half of the molecule (rod) from rat embryonic, neonatal, and adult fast and slow myosin, as well as myosin from cardiac ventricles. All of these S-1 and rod fragments were different, indicating that the previously reported differences among these different myosin heavy chain isozymes are located in both the S-1 and rod subfragments for all myosins examined. However, the polypeptide maps of neonatal and adult fast S-1 show clear similarities, as do the maps of slow and cardiac S-1. These similarities in the two pairs of polypeptide maps were confirmed by the results of immunoblotting experiments using antibodies to adult fast and to slow myosin.     

Structure elucidation of a senescence cross-link from human extracellular matrix. Implication of pentoses in the aging process

Isolation and structure elucidation of an acid-resistant fluorescent molecule from human extracellular matrix revealed the presence of an imidazo[4,5-b]pyridinium molecule comprising a lysine and an arginine residue cross-linked by a pentose. Structure confirmation was achieved in vitro by the nonenzymatic reaction of ribose with lysine and arginine residues. The cross-link, named pentosidine, could also be synthesized with isomers of ribose, arabinose, xylose, and lyxose as well as by incubating young human collagen with these sugars at 37 degrees C. Pentosidine was found in a variety of human tissues including plasma proteins and red blood cells. Its presence in cells grown in culture strongly suggests ribose or ribonucleotide metabolites as precursors. The unexpected discovery of pentose-mediated protein cross-linking raises new questions concerning the aging process.