The effect of oxygen tension on colony formation and cell proliferation of amniotic fluid cellsin vitro

The effects of reduced oxygen concentrations in the gas phase over the culture medium on colony formation and cell proliferation were investigated in high and low cell density primary and secondary cultures of amniotic fluid cells. Using two standard culture methods (25 cm² plastic flasks and Leighton type tubes) a significantly reduced culture time was observed at high cell density for mass cultures by incubation within a low oxygen tension gas phase (2.5 per cent to 7.5 per cent O₂) instead of conventional air (18 per cent O₂). At low cell density colony formation was significantly enhanced in cultures grown at reduced oxygen tension. Using gas permeable membranes as support, lowering the oxygen tension from 7.5 per cent to 2.5 per cent yielded an increase in plating efficiency of cells from approximately 5 per cent to 25 per cent, whereas plating efficiency was less than 2 per cent for cells grown at ambient 18 per cent O₂. It is suggested that low oxygen tension in the gas phase is an effective means of enhancing clonal growth in amniotic fluid cell cultures, thereby reducing both culture time and risk of culture failure.     

Prenatal diagnosis of infantile GM 2 gangliosidosis type II (sandhoff disease) by detection of N-acetylglucosaminyl-oligosaccharides in amniotic fluid with high-performance liquid chromatography

Prenatal diagnosis of Sandhoff disease (infantile onset) at 16 weeks gestation has been made by detection and analysis of N-acetylglucosaminyl-oligosaccharides in amniotic fluid using high performance liquid chromatography. The elution profile for the branched chain oli-gosaccharides was identical with that obtained with neonatal and infantile Sandhoff urine. The concentration of the oligosaccharides in the fluid was 1/100th that of urine but when calculated relative to creatinine the levels were similar. No oligosaccharides were detected in normal control amniotic fluids (10 patients) at a similar gestational age. Based on the levels of the amniotic fluid oligosaccharides and the sensitivity limits of the assay, prenatal diagnosis of patients with the juvenile onset form of the disease may also be possible with this technique.     

First-trimester prenatal diagnosis of Sanfilippo C disease

At 10 weeks' gestation, chorionic villus biopsy was obtained from a woman at risk for Sanfilippo type C disease. Acetyl-CoA: α-glucosaminide N-acetyltransferase activity was markedly deficient. The pregnancy was terminated at 12 weeks' gestation and follow-up study on fetal fibroblasts confirmed the diagnosis.     

Removal of copper from a copper sulphate solution using an ultrasonic-electrolysis process

The application of ultrasonic-electrolysis process for the removal of copper is studied.In the ultrasonic field cavitation acts as jets and agitates the solution and breaks the barrier layer between the cathode surface and the bulk of the solution.Thus increases metal deposition on the cathode surface.The results show that an ultrasonic field is successful for the removal of low copper concentrations in solution.     

Scots pine needle surfaces on radial transects across the north boreal area of Finnish Lapland and the Kola Peninsula of Russia

To gain an understanding of the characteristics of the needle surfaces of naturally regenerated Scots pine (Pinus sylvestris L.) and their geographical distribution, eight physicochemical variables were investigated within the north boreal forest area. The visibly undamaged needles were collected in autumn 1990 from 114 plots (3-5 pines per plot) along radial transects from the Monchegorsk and Nikel smelters, emitting SO2 and heavy metals, on the Kola Peninsula, Russia, to Finnish Lapland. The needles were examined by scanning electron microscopy (SEM) and measured for surface wettability using the droplet contact angle (DCA) method. Significant geographical south-north and west-east patterns could be observed in needle surface characteristics, correlating with emissions from the smelters and to climate. Despite the slightly higher initial DCAs (61.4-87.6 degrees) towards the north, the pine needle surfaces of the northernmost transects exhibited higher annual needle wettability change (ANWC) and wax erosion rate (AWER), expressed as the reduction in DCAs and epistomatal wax tube distribution (WTD) during one year, respectively, but a lower occurrence of particles and fungal hyphae than those of more southern transects. The higher ANWC was related to higher atmospheric SO2 concentration, and to the lower long-term temperature sum, but not clearly to annual precipitation. In the Monchegorsk smelter area, the current needles exhibited, on average, a 15% higher WTD and seven degree larger DCA, resulting in more hydrophobic needle surfaces than in Finnish Lapland, but during their first year, both the AWER and ANWC, were greatly increased. In Finnish Lapland, 30%, of all the epistomatal wax tubes disappeared from the needle surface during the first year, the value being 70% for the pines located 8 km from the smelter. The mineral composition of the particles deposited on the needle surfaces mirrored that of the minerals being produced by the smelters (e.g. FexSx, CuFeS2, NixSx, FexOx). Stomatal densities were in the range of 71.1-141.7 stomata mm(-2). The lower densities of stomata on needles close to the smelters correlated with reduced number of needle age classes of the pines, higher dry weights, higher pollutant accumulation and lower Mn and Zn concentrations in the needles. The AWER and ANWC were able to indicate the most seriously deteriorated needle surfaces on a regional scale, e.g. including the surroundings of both smelters, although the plot-specific relationships between 'needle surface variables' and 'pollution variables' were generally weak. The present study showed that the exposure of pine needles to the combined effects of ambient pollutants and harsh climate led to a deterioration in the physicochemical characteristics of the epicuticular wax, which may have serious ecophysiological consequences in the long term.     

Vertical gradients of ozone and carbon dioxide within a deciduous forest in Central Pennsylvania

Ambient concentrations of ozone (O(3)) and carbon dioxide (CO(2)) were measured at locations from the forest floor to the top of the canopy in a deciduous forest at the Moshannon State Forest in northcentral Pennsylvania. O(3) concentrations were measured from May-September for three years (1993-1995) while CO(2) concentrations were measured only during July and August of 1994. O(3) concentrations increased steadily during the day at all locations, peaking during the middle to late afternoon hours. O(3) concentrations then steadily declined to their lowest point, just before dawn. Vertical O(3) concentration gradients varied seasonally and among years. However, O(3) concentrations were highest within the forest canopy and lowest at the forest floor, with an average difference of approximately 13%. Differences in O(3) concentrations between the canopy and forest floor were greatest at night. O(3) concentrations were slightly higher at locations within the canopy than above the canopy. CO(2) concentrations were consistenly higher near the forest floor and were higher above the canopy than within the canopy. CO(2) concentrations were higher at night than during the day at all locations, especially near the forest floor.     

Persistent organochlorines in beluga whales (Delphinapterus leucas) from the St Lawrence River estuary--II. Temporal trends, 1982-1994

Blubber samples from 16 dead beluga whales (Delphinapterus leucas) collected during 1993-1994 in the St Lawrence River estuary were analysed for PCB congeners and other persistent organochlorines (DDT-group, chlorinated bornanes (toxaphene, CHB), chlordane SigmaCHL), hexachloro-cyclohexanes (SigmaHCH), chlorobenzenes (SigmaCBz), tris(p-chlorophenyl methane (TPMe) and mirex). Concentrations and relative proportions of major individual organochlorine components were within the same range as previous results for this population. Temporal trends were studied by combining the results with data from the analysis of 44 samples (1986-1990) and (for DDT and Aroclor PCBs only) with 20 samples (1982-1985) reported by Martineau et al., 1987. Results were lipid normalized and then age-adjusted by an ANCOVA model. Significant relationships between age and concentrations of most organochlorine groups were found for females but not for males. Significant declines were observed in SigmaDDT, and Aroclor PCBs (1.5- and 1.9-fold, respectively) in males between the 1982-1985 and 1993-1994 collection periods. Significant declines were also observed for SigmaHCH and SigmaCBz in males between 1986-1988 and 1993-1994. Mean concentrations of CHBs were significantly higher in 1993-1994 than in earlier years while dieldrin, SigmaCHL, mirex, and TPMe showed no trend. Declines in concentrations of major organochlorine groups were not observed in females possibly because of higher year to year, and within year, variation. The temporal trend in DDT and PCB concentrations in male beluga blubber paralleled trends in seals, eels, and seabirds in the St Lawrence estuary observed during the 1980s.     

Organic carbon concentration profiles in recent cave sediments: records of agricultural pollution or diagenesis?

Recent (<7 years old) cave sediments in Speedwell Cavern, Derbyshire, show an approximately exponential decay of organic carbon with depth. This phenomenon was thought to be due to one of two causes: (i) changing agricultural practice within the catchment feeding the cave, especially the increased use of sewage sludge and animal slurry as fertilizer; (ii) a relatively constant organic carbon concentration over time in the input sediment, with subsequent carbon mineralization during diagenesis. Carbon isotope composition of the organic material and the evolution of H/C ratio with depth indicate that the latter hypothesis is correct and that the profiles result from microbial diagenesis, not increased organic carbon inputs. By comparison with sediment of known (7 years) age, temporal decay constants for organic matter can be derived; these lie between rates previously determined for organic matter decomposition in marine sediments and soils. The H/C ratio of organic matter can be modelled as a function of time and proceeds in a similar fashion to soil organic material.