Glyphosate is the world's most widely used herbicide. It is nonselective and has been used to control a broad range of weed species for the past 20 yr, without the appearance of resistant weed biotypes. However, a biotype ofLolium rigidumfrom a field in Northern Victoria, Australia, in which glyphosate had been used for the past 15 yr, failed to be controlled by label recommended rates. Based on LD50values from pot dose-response experiments, this biotype exhibited resistance to glyphosate and was nearly 10-fold more resistant compared to the susceptible biotypes tested. The biotype was resistant to three different salts of glyphosate. The biotype was also nearly threefold more resistant to diclofop-methyl but was susceptible to other commonly used selective and broad-spectrum herbicides. Between the two-leaf and tillering stages of development, a susceptible biotype exhibited a small but significant decrease in tolerance to glyphosate, whereas tolerance of the resistant biotype remained unchanged with age. The resistant phenotype was verified in experiments in which seed was germinated in the presence of glyphosate. Observations on shoot and root growth of seedlings in these experiments suggested that the resistance mechanism might be associated more with the shoot than with the root.

Abstract. A heat-labile factor in cell-free filtrate of a Vibrio cholerae culture induces a marked rise in the wet-weight concentration of adenosine 3': 5'-cyclic monophosphate (cyclic AMP) in the intestinal mucosa of the dog. The increase becomes appreciable 1-1.5 hr after intraluminal administration of the filtrate, about the same time as the onset of intestinal secretion in response to a heat-labile enterotoxin in the filtrate. These results are consistent with the hypothesis that cyclic AMP may be an intermediary in the intestinal secretory response to cholera toxin.When added to sheets of isolated rabbit ileal mucosa, adenosine 3':5'-cyclic monophosphate (cyclic AMP) induces an abrupt reversal of net chloride flux from the absorptive to the secretory direction, along with other ion-flux changes.' If water accompanies the ions isosmotically a substantial secretion of fluid should result. In vivo as well as in vitro, agents that may increase concentrations of cyclic AMP in other tissues (prostaglandins) or potentiate such elevation (theophylline) also induce net intestinal secretion of ions and, at least in vivo, of water.'4 Similar indirect evidence suggests that cyclic AMP may play a physiological role not only in intestinal secretion but also in various other gastrointestinal secretory processes.-So far as we know, however, an increase in tissue concentrations of cyclic AMP has not been demonstrated in any gastrointestinal secretory state (see note added in proof).A heat-labile enterotoxic moiety found in cell-free filtrates of Vibrio cholerae cultures evokes a profuse intestinal secretion in several species.6'7 Such filtrates are reported2 48 to have effects on intestinal ion fluxes in vitro, and on fluxes of water and ions in vivo, closely mimicking those of exogenous cyclic AMP, prostaglandins, and theophylline. It has therefore been suggested' 4 that the mechanism by which cholera enterotoxin induces intestinal secretion may involve cyclic AMP. The plausibility of this hypothesis is not diminished by recent reports that partially purified cholera enterotoxin in low concentrations also mimics one effect of cyclic AMP in a functionally quite different system, the fat cell, where it stimulates lipolysis.9 10 As yet, however, it has not been directly demonstrated that a cell-free filtrate of a V. cholerae culture can induce a rise in 851

The effectiveness of a recently invented “steam pasteurization” (S) process in reducing pathogenic bacterial populations on surfaces of freshly slaughtered beef was determined and compared with that of other standard commercial methods including knife trimming (T), water washing (35°C; W), hot water/steam vacuum spot cleaning (V), and spraying with 2% vol/vol lactic acid (54°C, pH 2.25; L). These decontamination treatments were tested individually and in combinations. Cutaneus trunci muscles from freshly slaughtered steers were inoculated with feces containing Listeria monocytogenes Scott A, Escherichia coli OI57:H7, and Salmonella typhimurium over a predesignated meat surface area, resulting in initial populations of ca. 5 log CFU/cm2 of each pathogen. Tissue samples were excised from each portion before and after decontamination treatments, and mean population reductions were determined. Treatment combinations evaluated were the following (treatment designations within the abbreviations indicate the order of application): TW, TWS, WS, VW, VWS, TWLS, and VWLS. These combinations resulted in reductions ranging from 3.5 to 5.3 log CFU/cm2 in all three pathogen populations. The TW, TWS, WS, TWLS, and VWLS combinations were equally effective (P > 0.05), resulting in reductions ranging from 4.2 to 5.3 log CFU/cm2. When used individually, T, V, and S resulted in pathogen reductions ranging from 2.5 to 3.7 log CFU/cm2 Steam pasteurization consistently provided numerically greater pathogen reductions than T or V. Treatments T, V, and S were all more effective than W (which gave a reduction on the order of 1.0 log CFU/cm2). Steam pasteurization is an effective method for reducing pathogenic bacterial populations on surfaces of freshly slaughtered beef, with multiple decontamination procedures providing greatest overall reductions.

Field and controlled environment studies were conducted to evaluate the effects of certain environmental factors on the persistence of buried seed of annual ryegrass (Lolium multiflorum Lain.), a free‐volunteering species; and perennial ryegrass (Lolium perenne L.), nonpersistent species. Buried seed of annual ryegrass persisted in both nondormant and dormant condition. Buried seed of perennial ryegrass lost virtually all viability after 60 days of burial in the field. This dissipation occurred largely via in situ germination. Dormancy was induced in annual ryegrass when seeds were buried in cold, wet soils. High soil temperature associated with intermediate soil moisture level was effective in depleting viable seed through in situ germination. Loss of buried seed viability increased with soil temperature and moisture.