Advantages of the Use of Deciduous Teeth,Hair, and Blood Analysis for Lead and Cadmium Bio-Monitoring in Children. A Study of 6-Year-Old Children from Krakow (Poland)

The population of about 300 6-year-old preschool children was studied for lead (Pb) and cadmium (Cd) in deciduous teeth, scalp hair, and capillary blood. Zinc (Zn) content in hair was also measured due to its possible interferences with the elements studied. The Pb and Cd contents were measured by graphite furnace atomic absorption spectrometry with Zeeman background correction, and Zn, by flame method. Metal levels found were comparable to those in European countries. Positive correlations between Pb and Cd in the same and different tissues were widespread (r = 0.23–0.68). A positive correlation was found between Pb in teeth and blood (r = 0.65, p < 0.001). Pb blood threshold 100 μg L⁻¹ referred to 2.6 μg g⁻¹ Pb in teeth. Predictability of this Pb teeth limit was 14% vs. 5% for Pb blood. Strong negative correlation was found between hair Pb and Zn (r = −0.68, p < 0.001). Enhanced Cd and Zn levels in hair were associated with the household drinking water hardness. The associations with some other environmental and behavioral factors were also presented and discussed. The results proved the advantage of analysis of primary teeth for Pb exposure screening of preschool children.     

Tomato yellow leaf curl virus DNA in callus cultures derived from infected tomato leaves

Callus cultures were induced from leaves of a tomato plant infected with tomato yellow leaf curl virus (TYLCV) and analyzed for viral DNA presence during successive subcultures. No TYLCV DNA was detected in calli sampled after eight months of culture. Considerable differences in the presence of TYLCV DNA were found within sectors of a callus culture and between different callus cultures, throughout the entire eight months period. Infected calli which were cultured at sub-optimal temperature (15°C) retained the viral DNA longer than at 25 °C. The results suggested that TYLCV disappearance during callus culture was due to a disruption of some of the cell-to-cell connections, resulting in islands of infected cells in the midst of uninfected tissue and/or to the competition between the rate of cell division and that of viral DNA replication.Abbreviations BA benzyladenine - CMV cucumber mosaic virus - NAA naphthaleneacetic acid - TMV tobacco mosaic virus - TYLCV tomato yellow leaf curl virus     

Cytopathology of Tomato torrado virus Infection in Tomato and Nicotiana benthamiana

Electron microscopy studies were carried out to investigate the cytopathological changes induced in tomato leaves by Tomato torrado virus (ToTV) that infects tomato plants worldwide causing severe necrotic symptoms. Plants infected with one of the Polish isolates of ToTV were used for cytopathological research. The results revealed severe cellular alterations, especially in Solanum lycopersicum. Moreover, it was shown that crystalline aggregates of virions occurred not only within the phloem cells as it has been previously reported.     

Correction of timing errors in photomultiplier tubes used in phase-modulation fluorometry

The measurement of fluorescence lifetimes is known to be hindered by the wavelenght-dependent and photocathode area-dependent time response of photomultiplier tubes. A simple and direct method is described to minimize the effects in photomultiplier tubes for phase-modulation fluorometry. Reference fluorophores of known lifetime were used in place of the usual scattering reference. The emission wavelenghts of the reference and sample were matched by either filters or a monochromator, and the use of a fluorophore rather than a scatter decreases the differences in spatial distribution of light emanating from the reference and sample. Thus photomultiplier tube artifacts are minimized. Five reference fluorophores were selected on the basis of availability, ease of solution preparation, and constancy of lifetime with temperature and emission wavelenght. These compounds are p-terphenyl, PPO, PPD, POPOP and dimethyl POPOP. These compounds are dissolved in ethanol to give standard solutions that can be used over the temperature range from ?55 to +55°C. Purging with inert gas is not necessary. The measured phase and modulation of the reference solution is used, in conjunction with the known reference, lifetime, to calculate the actual phase and modulation of the exictation beam. The use of standard fluorophores does not require separate experiments to quantify photomultiplier effects, and does not increase the time required for the measurement of fluorescence lifetimes. Examples are presented which demonstrate the elimination of artifactual photomultiplier effects in measurements of the lifetimes of DADH (0.4 ns) and indole solutions quenched by iodide. In addition, the use of these reference solutions increases the accuracy of fluorescence lifetime measurements ranging ranging to 30 ns. We judge this method to provide more reliable lifetime measurements by the phase and modulation method. The test solutions and procedures we describe may be used by other laboratories to evaluate the performance of their phase fluorometers.     

Low temperature seed germination of several tomato genotypes

Environmental stresses at particularly vulnerable stages during crop development may severely diminish productivity. At temperature of 10 °C or below cultivated tomato germinate slowly if at all. In this study, seven tomato genotypes bred at the Research Institute of Vegetable Crops were evaluated for germination time at 10 °C. Analysis identified that one genotype which has L. chilense in its pedigree, germinated most rapidly while four other genotypes germinated slower. After 21 days, four out of five of the genotypes resulted in seed germination from 81 to 98 %.     

Chemical and sensory characteristics of the fruits of eight cultivars of field grown tomato

The physical and sensory characteristics of tomato fruits (cf. Gajc-Wolska et al.: Physical and sensory characteristics of the fruits …, this issue) were supplemented by total sugars and titratable acid analysis and flavor. The instrumental and sensory methods were highly statistically correlated. Comparison of cultivars always requires that physical and chemical analysis of tomato fruit quality should always include results of sensory evaluation.     

Spectroscopic and potentiometric evidence for the stabilization of a bent structure of octapeptides by Cu(II) ions

Syntheses and the results of a potentiometric and spectrophotometric study at 25°C and an ionic strength of 0.10 mol dm^?3 (KNO₃) of the H ⁺ and Cu²⁺ complexes of two pairs of tetra- and octapeptides are reported. The peptides, Gly-Gly-Pro-Gly and (Gly-Gly-Pro-Gly)₂, and Gly-Gly-Pro-Lys and (Gly-Gly-Pro-Lys)₂, are models for the biologically active octapeptide with antitumor activity, dog tuftsinyltuftsin. The results clearly demonstrate participation of the ?-NH₂ group of -Lys- in metal ion coordination from below pH 6 and, with the octapeptides at high pH, suggest the presence of a bent conformation with a large chelate ring spanning the two ends of the peptide chain.     

Effect of jasmonates and exogenous polysaccharides on production of alkannin pigments in suspension cultures of Alkanna tinctoria

Summary The conditions for the efficient production of alkannin pigments by a suspension culture of Alkanna tinctoria were established. Pectin, polygalacturonic acid sodium salt and galactan increased the pigment production but not as much as agar did. A marked increase in the pigment content in cells and medium of suspension cultures after treatment with methyl jasmonate was observed. It was shown, applying a two-layer culture method, that mineral and olive oils intensified the pigment secretion from cells to the medium but did not enhance significantly their synthesis. Thin layer chromatography and high performance liquid chromatography methods showed that two main esters of alkannin are responsible for the characteristic colour of A. tinctoria suspension cultures.Abbreviations BAP 6-benzylaminopurine - 2,4-D 2,4-dichlorophenoxyacetic acid - IAA indole 3-acetic acid - NAA 1-naphthaleneacetic acid - MeJA methyl jasmonate - TLC thin layer chromatography - HPLC high performance liquid chromatography