Comparative effects of various classes of mouse interferons on macrophage activation for tumor cell killing

The effects of mouse interferon-alpha (MuIFN-alpha), -beta (MuIFN-beta), and -gamma (MuIFN-gamma) on macrophage activation for tumor cell killing were determined by using proteose peptone-elicited peritoneal macrophages from C3H/HeN and C3H/HeJ mice under conditions that either included or were free of detectable endotoxin. Alone, under the conditions used, none of the interferons was able to activate macrophages directly for tumor cell killing. However, with a second signal provided to responsive macrophages by contaminating endotoxin, added bacterial lipopolysaccharide (LPS), or heat-killed Listeria monocytogenes (HKLM), all three types of interferon induced cytolytic activity, with MuIFN-gamma approximately 500 to 1000-fold more active than either MuIFN-alpha or -beta. Thus, all three interferons were able to prime macrophages for killing but required a second signal before cytolytic activity could be expressed. When MuIFN-gamma was mixed with either MuIFN-alpha or -beta and placed on macrophages, little or no killing developed. Mixtures of MuIFN-gamma with either MuIFN-alpha or -beta did increase the sensitivity of macrophages to triggering by LPS, however, compared with macrophages treated with MuIFN-gamma alone. The results are collectively important because they i) confirm that significant quantitative differences exist between the various interferons with regard to their capacity to prime macrophages for tumor cell killing; ii) indicate that to be an efficient activator each type of interferon must be combined with a second stimulus, such as LPS or HKLM; iii) show that neither MuIFN-alpha nor -beta can provide an efficient second triggering signal for macrophages that are primed by MuIFN-gamma; and iv) document that mixtures of MuIFN-gamma with either MuIFN-alpha or -beta are most efficient at inducing priming, compared with any one of the interferons used alone.     

The secondary structure of ribonuclease P RNA, the catalytic element of a ribonucleoprotein enzyme

Secondary structure models for the ribonuclease (RNAase) P RNAs of Bacillus subtilis and E. coli were derived by a phylogenetic comparative analysis of published sequences as well as four novel ones. The RNAase P RNA genes from Bacillus megaterium, Bacillus brevis, Bacillus stearothermophilus, and Pseudomonas fluorescens were cloned, sequenced, and compared with the other available sequences. Regions of pairing were identified by the occurrence of homologous complementary sequences that vary among the compared molecules. A common core of primary and secondary structure can be identified in all these RNAase P RNAs. The previously noted striking differences between the Bacillus and the enteric RNAase P RNAs arise not only from point mutations, but from the addition or deletion of structural domains. The primary and secondary structural features that are common to all of the RNAase P RNAs are likely to be the elements involved in the binding and cleavage of tRNA precursors, and in the interaction with the RNAase P protein.     

Variability and transport of suspended sediment,particulate and dissolved organic carbon in the tidal freshwater Hudson River

Measurements of suspended matter, particulate organic carbon and dissolved organic carbon were made over a three year period at stations spanning 150 km of the tidal freshwater Hudson River. Suspended matter concentrations varied from year-to-year and were not related to freshwater discharge. The increase in suspended matter with depth in vertical profiles suggests that, during medium to low flow conditions, resuspension of bottom sediments was as important a source of sediment as loadings from tributaries. Particulate organic carbon showed significant variability among stations, and both autochthonous primary production and detrital organic matter are contributing to POC standing stocks. Dissolved organic carbon represented over half of the total organic carbon in the water column and showed little variation among stations.Examining downstream changes in transport showed that there was significant production of both suspended matter and POC within the study reach during the ice-free season. Tributary loadings within the study reach do not appear to be the cause of these increases in downstream transport. Dissolved organic carbon behaved conservatively in that there was no evidence for net production or net consumption within the river.The spatial/temporal patterns and analyses of transport suggest that suspended matter and POC, but not DOC, were controlled to a significant extent by processes occurring within the river and were not simply related to loadings from outside.     

Assessment of spermatozoal function using dual fluorescent staining and flow cytometric analyses

Spermatozoa from bulls, boars, dogs, horses, mice, and men were examined using a fluorogenic stain consisting of the membrane-permeant substrate carboxyfluorescin diacetate (CFDA) and the relatively membrane-impermeant nuclear stain propidium iodide (PI). Three distinct populations of spermatozoa were discernible in samples from each species upon microscopic examination. Individual spermatozoa, presumed to be viable because of their motility, retained products of the fluorescein chromophore throughout the cell. A second population of spermatozoa in which the nuclei stained red with PI retained the green fluorescein fluorophore mainly in the acrosome. A third population, presumed to be degenerate spermatozoa, possessed only red fluorescent nuclei. These populations were quantified using dual parameter flow cytometry in 14 samples of cryopreserved bovine spermatozoa for which fertility and seminal quality data were available. Flow cytometric analyses were highly correlated with other seminal quality measurements. Sequential flow cytometric analyses provided the ability to rapidly quantitate changes in specific fluorescently stained populations. The ability to make rapid quantitative measurements should allow development of new and presumably more reliable information on the functional aspects of spermatozoa.     

The occurrence of cyclic AMP in archaebacteria

Cyclic AMP was found in species representative of the three major groups of the archaebacteria. In Methanobacterium thermoautotrophicum starvation for H2 led to a significant increase in cellular cAMP. The findings suggest that the occurrence of cAMP antedates the divergence of the major kingdoms of biology; the observations also imply that cAMP constitutes a very early regulatory molecule.     

The S-state dependence of Cl binding to plant Photosystem II

A combined single-turnover flash and ³⁵Cl NMR technique has been used to monitor S-state dependence of Cl⁻ binding to PS-II particles derived from mangrove (Avicennia marina). No detectable high-affinity binding was found to particles in the S₀ and S₁ states, but binding with an affinity comparable to that which activates O₂ evolution was found in the S₂ and S₃ states.     

Induction of interleukin 2 from a murine B cell tumor by a factor found in immune serum

The murine B cell tumor line 2 PK-3 secretes T cell growth factor activity after incubation for 6 to 48 hr with a factor present in heterologous immune serum. T cell growth factor derived from 2 PK-3 was compared with IL 2 produced by the Con A-induced T lymphoma cell line EL-4 G12. These studies indicated that T cell growth factor activities derived from both cell lines were similar with respect to m.w., pI values, and the ability to support growth of two IL 2-dependent T cell clones. Three preparations of immune sera were found to be active in the induction of IL 2 activity from 2 PK-3 cells, including rabbit anti-mouse brain, rabbit anti-complete Freund's adjuvant, and goat anti-mouse Ig. None of these preparations, however, induced IL 2 from EL-4 G12 cells. It was also observed that LPS synergized with immune serum to produce enhanced activity. Normal sera prepared from unimmunized animals were not active in the induction of IL 2 activity. Fractionation of immune serum on protein A Sepharose suggested that the IL 2-inducing agent is not IgG.     

Seasonal dynamics of rotifer and crustacean zooplankton populations in a eutrophic,monomictic lake with a note on rotifer sampling techniques

The abundances, biomass, and seasonal succession of rotifer and crustacean zooplankton were examined in a man-made, eutrophic lake, Lake Oglethorpe, over a 13 month period. There was an inverse correlation between the abundance of rotifers and crustaceans. Rotifers were most abundant and dominated (>69%) the rotifer-crustacean biomass during summer months (June–September) while crustacean zooplankton dominated during the remainder of the year (>89%). Peak biomasses of crustaceans were observed in the fall (151 µg dry wt l^–1 in October) and spring (89.66 µg dry wt l^–1 in May). Mean annual biomass levels were 46.99 µg dry wt l^–1 for crustaceans and 19.26 µg dry wt l^–1 for rotifers. Trichocerca rousseleti, Polyarthra sp., Keratella cochlearis and Kellicottia bostoniensis were the most abundant rotifers in the lake. Diaptomus siciloides and Daphnia parvula were the most abundant crustaceans. Lake Oglethorpe is distinct in having an unusually high abundance of rotifers (range 217–7980 l^–1). These high densities can be attributed not only to the eutrophic conditions of the lake but also to the detailed sampling methods employed in this study.The research was supported by National Science Foundation grants DEB 7725354 and DEB 8005582 to Dr. K. G. Porter. It is lake Oglethorpe Limnological Association Contribution No. 25 and Contribution No. 371 of the Harbor Branch Foundation, Inc.     

The conserved 5 S rRNA complement to tRNA is not required for translation of natural mRNA

We have tested a putative base-paired interaction between the conserved GT psi C sequence of tRNA and the conserved GAAC47 sequence of 5 S ribosomal RNA by in vitro protein synthesis using ribosomes containing deletions in this region of 5 S rRNA. Ribosomes reconstituted with 5 S rRNA possessing a single break between residues 41 and 42, deletion of residues 42-46, or deletion of residues 42-52 were tested for their ability to translate phage MS2 RNA. Initiator tRNA binding, aminoacyl-tRNA binding, ppGpp synthesis, and miscoding were also tested. All of the measured functions could be carried out by ribosomes carrying the deleted 5 S rRNAs. The sizes and relative amounts of the polypeptides synthesized by MS2 RNA-programmed ribosomes were identical whether or not the 5 S RNA contained deletions. Aminoacyl-tRNA binding and miscoding were essentially unaffected. Significant reduction in ApUpG (but not poly(A,U,G) or MS2 RNA)-directed fMet-tRNA binding and ppGpp synthesis were observed, particularly in the case of the larger (residues 42-52) deletion. We conclude that if tRNA and 5 S rRNA interact in this fashion, it is not an obligatory step in protein synthesis.