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SummaryDeletion of gene Rv3676 in Mycobacterium tuberculosis coding for a transcription factor belonging to the cAMP receptor protein (CRP) family caused growth defects in laboratory medium, in bone marrowderived macrophages and in a mouse model of tuberculosis. Transcript profiling of M. tuberculosis grown in vitro identified 16 genes with significantly altered expression in the mutant compared with the wild type. Analysis of the DNA sequences upstream of the corresponding open reading frames revealed that 12 possessed sequences related to a consensus CRP binding site that could represent the sites of action of Rv3676. These included rpfA , lprQ , whiB1 and ahpC among genes with enhanced expression in the wild type, and Rv3616c-Rv3613c, Rv0188 and lipQ among genes exhibiting enhanced expression in the mutant. The activity of an rpfA :: lacZ promoter fusion was lowered in the Rv3676 mutant and by mutation of the predicted Rv3676 binding site. Moreover, the product of Rv3676 (isolated as a TrxA fusion protein) interacted specifically with the rpfA promoter, and binding was inhibited by mutation of the Rv3676 site. Although Rv3676 retains four of the six amino acid residues that bind cAMP in Escherichia coli CRP addition of cAMP did not enhance Rv3676 binding at the rpfA promoter in vitro . In summary, it has been shown that Rv3676 is a direct regulator of rpfA expression, and because rpfA codes for a resuscitation promoting factor this may implicate Rv3676 in reactivation of dormant M. tuberculosis infections.

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SUMMARYThe role of ectomycorrhizas in the metal tolerance of birch seedlings from Sudbury, Ontario was investigated. Betula papyrifera Marsh, is one of the few tree species able to survive in the copper-and nickel-polluted area near Sudbury. Two types of birch seedlings were tested; those inoculated with Laccaria proxima (Boud.) Pat., Lactarius hibbardae Peck, Lactarius rufus (Scop, ex Fr.) Fries, or Scleroderma fiavidum E. & E. isolates originating from the Sudbury area, and those which were not inoculated. Once the seedlings were infected, they were grown in sand culture containing 34 or 85 fiM Ni, 32 or 63 fiM Cu, or a control solution. At the low nickel concentration, the mycorrhizal plants, especially those infected with S. fiavidum, grew significantly better than did non-mycorrhizal plants. At the higher nickel concentration, S.flaviduminfected seedlings weighed 86 % of controls without nickel, while the other seedlings weighed only 52 to 61 % of control. The good growth of 5. fiavidum-'mfected birch seedlings may have been due to retention of nickel in the mycorrhizas. These seedlings had the highest root nickel contents and the lowest stem nickel contents. At the high concentration of copper, growth of the mycorrhizal seedlings was significantly reduced compared with the non-mycorrhizal seedlings. This reduction in growth of infected seedlings did not relate to an increase in the uptake or translocation of copper. Under the low copper treatment, infection with mycorrhizal fungi did not affect seedling growth. The potential role of iron and phosphorus in affecting host metal tolerance was investigated. Changes in the tissue concentrations of these elements did not relate to the effect of the fungi on metal tolerance.

The inputs of the airborne pollutants nickel, copper, iron, and sulfur were determined in bulk dustfall–rainfall collection and in snow samples taken along transects originating at a large nickel–copper smelter near Sudbury, Ontario. Determinations were made from 1975 to 1978, which was subsequent to the building of a 380-m smokestack at the smelter in 1972. Atmospheric SO2 was also monitored, using sulfation plates. Higher levels of all smelter pollutants occurred at sites closer to the smelter, compared with sites as far as 60 km SSE. All bulk rainwater samples collected along a 60-km transect SSE of the smelter were found to be acidic, most with a pH of less than 4.0. Since there was no clear gradient of acidity with distance from the smelter, it appears that the acidic precipitation problem is a severe regional one. Simple deposition budgets based on data collected on six 30-day sampling intervals in 1976 and 1977 indicate that less than 3% of the sulfur emitted from the smelter was deposited within a 60-km radius. In contrast, about 42% of the nickel, 40% of the copper, and 52% of the iron emitted from the smelter were calculated to be deposited within a 60-km radius.The contamination of forest soils, soil litter, and vegetation by copper, nickel, iron, and sulfur at sites closer to the smelter has been caused by past as well as ongoing emissions. In soil profiles, the metals were concentrated in the surface organic horizons, relative to deeper mineral soils. Surface soils up to 70 km from the smelter showed elevated nickel and copper concentrations. Elevated concentrations of these same metals in the foliage of a number of tree species were detectable at least to 12 km from the smelter. The horsetail Equisetum sylvaticum showed especially high concentrations of sulfur, while the moss Polytrichum commune was an accumulator of nickel, copper, and sulfur at sites up to 6 km. No consistent trends with distance occurred for foliar levels of the bases calcium, magnesium, and potassium. However, higher calcium concentrations occurred in forest litter collected at control sites, compared with sites closer to the smelter.

Records of reproduction in a Miami colony of squirrel monkeys living in a seminatural state and of monkeys in the field indicate that the male undergoes an annual testis cycle. The spermatogenic phase is associated with the seasonal acquisition of a secondary sexual characteristic which we have termed the "fatted" condition. Body weights, measurements of subcutaneous fat, and testicular histology studied over a 12-month period further establish this cycle. Climatological analyses suggest that this cycle is associated with the precipitation cycles of the respective environments.

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Soil, vegetation, and rainfall, have been collected in the vicinity of a nickel–copper smelter at Sudbury, Ontario. The region is a major producer of many metals, and the large areas of forest desolation in the vicinity have been ascribed to sulphur dioxide fumigations over the past 80 years. In the present study, attention has been focused on potentially toxic heavy metals. Very elevated soil levels of nickel and copper were found, with values up to 5,104 ppm Ni and 2,892 ppm Cu within 1.1 km of the smelter. The concentrations decreased with distance to 49.8 km in one direction. Surface soils were the most contaminated, and a decline through the soil profile was found. Other metals such as iron, cobalt, and silver, showed a similar pattern of distance and depth, suggestive of an airborne source. Analyses of the foliage of three plant species also showed excessive levels of nickel and copper, as well as of aluminium. The levels declined with distance from the smelter.The relative possibilities of soilversusaerial uptake are considered. The soils within 2–3 km of the smelter were markedly more acidic than those from farther away, and this was paralleled by their increased conductivity. Dustfall–rainfall collections and analyses of the soluble heavy metals indicated that a major aerial source of metals existed, and that the problem of metallic emissions is not merely one of the past. Heavy metals are persistent in soils, and the ecological consequences to date have perhaps only been masked around Sudbury by the sulphur dioxide damage, and the particular importance attached to it in the past.