Flavone-8-acetic acid augments systemic natural killer cell activity and synergizes with IL-2 for treatment of murine renal cancer

The investigational drug flavone-8-acetic acid (FAA) potently augments NK activity in the spleen, liver, lungs, and peritoneum in a dose-dependent manner after i.v. or i.p. administration. Augmented NK activity peaks by 24 h after FAA injection and returns to normal after 6 days. Combined treatment of established murine renal cancer with FAA and rIL-2 results in up to 80% long term survival whereas FAA or rIL-2 alone were unable to induce any long term survivors. The optimal dose of rIL-2 required for use with FAA was in the range of 10,000 to 30,000 U/day. Further studies demonstrated that the regimen of FAA plus rIL-2 administration that was effective in treating established murine renal cancer also induced a more potent augmentation of NK activity than did either FAA or rIL-2 alone. Subsequent studies revealed that the therapeutic effectiveness of FAA plus rIL-2 was significantly reduced when tumor-bearing mice were treated with anti-asialo GM1 serum. These results are consistent with a role for augmented NK activity in the therapeutic effects of FAA plus rIL-2 murine renal cancer. In addition, these studies demonstrate that FAA and rIL-2 is a useful approach for cancer treatment in that subtoxic doses of rIL-2 can be used and significant anti-tumor efficacy occurs even without accompanying adoptive immunotherapy.     

"Imposed" and "inherent" mucosal activity patterns. Their composite representation of olfactory stimuli

Both regional differences in mucosal sensitivity and a gas chromatography-like process along the mucosal sheet have been separately proposed in two sets of earlier studies to produce different odorant-dependent activity patterns across the olfactory mucosa. This investigation evaluated, in one study, whether and to what degree these two mechanisms contribute to the generation of these activity patterns. Summated multiunit discharges were simultaneously recorded from lateral (LN) and medial (MN) sites on the bullfrog's olfactory nerve to sample the mucosal activity occurring near the internal and external nares, respectively. Precisely controlled sniffs of four odorants (benzaldehyde, butanol, geraniol, and octane) were drawn through the frog's olfactory sac in both the forward (H1) and reverse (H2) hale directions. By combining the four resulting measurements, LNH1, LNH2, MNH1, and MNH2, in different mathematical expressions, indexes reflecting the relative effects of the chromatographic process, regional sensitivity, and hale direction could be calculated. Most importantly, the chromatographic process and the regional sensitivity differences both contributed significantly to the mucosal activity patterns. However, their relative roles varied markedly among the four odorants, ranging from complete dominance by either one to substantial contributions from each. In general, the more strongly an odorant was sorbed by the mucosa, the greater was the relative effect of the chromatographic process; the weaker the sorption, the greater the relative effect of regional sensitivity. Similarly, the greater an odorant's sorption, the greater was the effect of hale direction. Other stimulus variables (sniff volume, sniff duration, and the number of molecules within the sniff) had marked effects upon the overall size of the response. For strongly sorbed odorants, the effect of increasing volume was positive; for a weakly sorbed odorant, it was negative. The reverse may be true for duration. In contrast, the effect of increasing the number of molecules was uniformly positive for all four odorants. However, there was little evidence that these other stimulus variables had a major influence upon the effects of the chromatographic process and regional sensitivity differences in their generation of mucosal activity patterns.     

Cytolytic activity and immunological similarity of the Bacillus thuringiensis subsp. israelensis and Bacillus thuringiensis subsp. morrisoni isolate PG-14 toxins.

The parasporal bodies of the mosquitocidal isolates of Bacillus thuringiensis subsp. israelensis and B. thuringiensis subsp. morrisoni isolate PG-14 were compared with regard to their hemolytic and cytolytic activities and the immunological relatedness of the 28- and 65-kilodalton (kDa) proteins that occur in both subspecies. The alkali-solubilized parasporal bodies of B. thuringiensis subsp. israelensis caused 50% lysis of human erythrocytes at 1.14 micrograms/ml, whereas those of B. thuringiensis subsp. morrisoni caused similar lysis at 1.84 micrograms/ml. Preincubation of solubilized parasporal bodies with dioleolyl phosphatidylcholine significantly inhibited the hemolytic activity of both supspecies. In cytolytic assays against Aedes albopictus cells, the toxin concentrations causing 50% lysis for B. thuringiensis subsp. israelensis and B. thuringiensis subsp. morrisoni were 1.87 and 11.98 micrograms/ml, respectively. Polyclonal antibodies raised separately against the 25-kDa protein (a tryptic digest of the 28-kDa protein) or the 65-kDa protein of B. thuringiensis subsp. israelensis cross-reacted, respectively, with the 28- and the 65-kDa proteins of B. thuringiensis subsp. morrisoni. However, neither of these antibodies cross-reacted with the 135-kDa protein of either subspecies. These results indicate that the mosquitocidal and hemolytic properties of B. thuringiensis subsp. israelensis and B. thuringiensis subsp. morrisoni isolate PG-14 are probably due to the biologically related proteins that are present in the parasporal bodies of both subspecies. The lower hemolytic activity of the B. thuringiensis subsp. morrisoni may be due to the presence of lower levels of the 28-kDa protein in that subspecies.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of harvest intensity and ground flora establishment on inorganic-N leaching from a Sitka spruce plantation in north Wales,UK

Inorganic-N concentrations in soil solution of whole tree harvest (WTH) and conventional fell (CF) plots were monitored for two years before felling and four years after felling. Concentrations in the mineral soil after felling were higher than in standing forest for up to 14 months in both felling treatments. In the WTH plots inorganic-N concentrations then dropped steadily until four years after felling they approached zero. In contrast, inorganic-N concentrations of the CF plots remained comparatively large. Inorganic-N was dominated by nitrate throughout the period of the study, and especially in the mineral horizons.Felling debris was not a source of inorganic-N, unless indirectly through release and mineralisation of soluble organic-N. Vegetation cover, biomass and N content were substantially greater in the WTH plots two to three years after felling, compared with the CF. Vegetation cover and brash cover (slash cover in N. America) were negatively correlated. There was also a negative correlation between inorganic-N concentration in soil water samplers and the vegetation cover within the collection area of, or a 1 m square surrounding, these samplers.Two factors are probably responsible for the reduction in inorganic-N concentrations after felling in the WTH — the rapid re-establishment of vegetation and the lack of a N source in felling debris. In the CF plots, brash prevents re-establishment of vegetation over wide areas for at least four years. However, brash is not directly a source of inorganic-N at this stage.     

Oosorption and oocyte loss in a terrestrial isopod under stressful conditions

An increased number of resorbed oocytes was observed in ovaries of terrestrial isopods which were kept under different experimental temperature and photophase regimes compared with those observed in the natural population. Regardless of the nature of the stimulus: high or low temperature or long and short photophases, the female always responded through oosorption. In an iteroparous species such as Porcellio ficulneus B.-L., recruitment of resources for future utilization could be its main response to adverse ambient conditions.     

Vertically stratified frugivore community composition and interaction frequency in a liana fruiting across forest strata

Vertical stratification is a key feature of tropical forests and structures plant–frugivore interactions. However, it is unclear whether vertical differences in plant-frugivore interactions are due to differences among strata in plant community composition or inherent preferences of frugivores for specific strata. To test this, we observed fruit removal of a diverse frugivore community on the liana Marcgravia longifolia in a Peruvian rain forest. Unlike most other plants, Marcgravia longifolia produces fruits across forest strata. This enabled us to study effects of vertical stratification on fruit removal without confounding effects of plant species and stratum. We found a high number of visits of a few frugivore species in the understorey and a low number of visits of many different frugivores in the canopy and midstorey. Whereas partial and opportunistic frugivores foraged across strata with differing frequencies, obligate frugivores were only found eating fruits in the higher strata. Avian frugivores foraging in the canopy were mainly large species with pointed wings, whereas under- and midstorey avian foragers were smaller with rounded wings. Our findings suggest a continuous shift in the frugivore community composition along the vertical gradient, from a few generalized frugivores in the understorey to a diverse set of specialized frugivores in the canopy. This shift in the frugivore community leads to correlated, reciprocal changes from specialized to generalized plant-frugivore interactions. Thus, we conclude that vertical niche differentiation between species in tropical forests persists even when food resources are available across strata. This highlights its role for promoting biodiversity and ecosystem functioning.     

The hmu locus of Yersinia pestis is essential for utilization of free haemin and haem-protein complexes as iron sources

Yersinia pestis strains utilize haem and several haem-protein complexes as sole sources of iron. In this study, the haemin uptake locus (hmu) of Y. pestis KIM6+ was selected from a genomic library by trans-duction into an Escherichia coli siderophore synthesis (entC) mutant. Recombinant plasmids containing a common 16 kb BamHI insert were isolated that allowed E. coli entC to use haemin as an iron source. An 8.6 kb region of this insert was found to be essential for haemin utilization and encoded at least five proteins with molecular masses of 79/77, 44, 37, 35, and 30/27.5 kDa. A 10.9 kb Clal fragment containing the hmu locus showed varying degrees of homology to genomic DNA from Yersinia pseudotuberculosis, Yersinia enter-ocolitica, and other genera of Enterobacteriaceae. An E. coli hemA aroB strain harbouring cloned hmu genes used haemin as both an iron and porphyrin source but only on iron-poor medium, suggesting that haemin uptake is tightly iron regulated. Additionally, haemoglobin and myoglobin were used as iron sources by an E. coli entC (pHMU2.2) strain. Deletion of the hmu locus from Y. pestis KIM6+ chromosome generated a mutant that grew poorly on iron-depleted medium containing free haemin as well as mammalian haem-protein complexes including haemoglobin, haemoglobin-haptoglobin, myoglobin, haem-haemopexin, and haem-albumin unless it was complemented with cloned hmu genes.