Excision and transposition of two Ds transposons from the bronze mutable 4 derivative 6856 allele of Zea mays L

Summary The regulatory mutation bronze mutable 4 Derivative 6856 (bz-m4 D6856) contains a complex 6.7 kb Dissociation (Ds) element tagged with a duplication of low copy bz 3 flanking sequences (Klein et al. 1988). This creates a unique opportunity to study the transposition of a single member of the repetitive family of Ds elements. Eighteen full purple revertants (Bz alleles) of bz-m4 were characterized enzymatically and by genomic mapping. For 17 of the Bz alleles, reversion to a wild-type phenotype was caused by excision of the 6.7 kb Ds transposon. Nine of these Bz alleles retained the transposon somewhere in their genome. In this study we show that like Ac (Schwartz 1989; Dooner and Belachew 1989), the 6.7 kb Ds element can transpose within a short physical distance, both proximal and distal to its original position. Additional bz sequences have been mapped immediately distal to the mutant locus in bz-m4 D6856; genetic evidence suggests these are flanked by two additional Ds elements. The remaining Bz revertant, Bz :107, arose from excision of a more complex 13 kb Ds element.     

Concentrations of essential elements after repeated administrations of tin and selenium

To study effects of simultaneous administration of tin (Sn) and selenium (Se) on concentrations of several essential elements, mice were injected with either SnCl2 (ip) or Na2SeO3 (sc), alone or both compounds at a daily dose of 5 mumol/kg each for 12 consecutive days. Mice were sacrificed at 20 h after the last injection and concentrations of Sn, Se, Na, Ca, Zn, P, Fe, K, and Mg in the liver, kidney, spleen, pancreas, testis, seminal vesicle, lung, femoral muscle, and femoral bone were determined. In the control mice, Sn and Se concentrations were the highest in bone (0.69 micrograms Sn and 6.93 micrograms Se/g dry wt). Administered Sn was found to accumulate in all organs except the testis. Among the essential elements determined, Na was the most affected in terms of concentration in the organs and Mg was the least affected element in these organs. Among the organs tested, each elemental concentration in the pancreas was most affected. Simultaneous injections of Sn and Se appeared to keep the correlation coefficients between elements similar to those found in the control mice.     

温州蜜柑果实发育过程中矿质营养元素含量的动态变化

本文分析了温州蜜柑丰产园不同发育阶段的果实氮、磷、钾、钙、镁、铁、锰、锌、铜、硼的含量。矿质元素在果实中的动态变化规律与叶片中的变化规律显然不同。一是含量比叶片低;二是浓度的最高峰期出现比叶片早。果实发育前中期元素含量变化较复杂,9月以后趋向稳定。对可否以9月至10月上旬作为采果样时期以进行营养诊断作了讨论。     

Trace elements in scalp hair of professional drivers and university teachers in Hong Kong

Hair samples of 23 male professional drivers and 20 male university teachers in Hong Kong were collected, and the concentrations of Al, Sb, As, Ca, Cu, Fe, Pb, Mg, Mn, Hg, K, Sr, S, V, and Zn were measured. Both of the target groups fell within the same age group of 35–45. The washing method of using detergent and powder was found to be comparable to that of using ether. Difference in the mean concentration of each detected element in the two groups was tested by the Student'st-test and the Wilcoxon rank-sums test. Hair concentrations of Al, Sb, Pb, Mg, Mn, and K in the «Driver Group» were significantly (p<0.05) higher than those in the “Teacher Group.” On the other hand, As and Hg were found to have a higher concentration in hair of teachers. Interpretation of the findings in terms of the environmental factor and the metabolic rate was attempted.     

Biological evaluation of trace element data in human ovaries by statistical analysis

Analysis of variance, analysis of covariance, correlation coefficient, multiple correlation, and partial correlation coefficient statistical tests were applied to Cs, Cr, Co, Fe, Rb, Sc, Se, and Zn content in human ovaries in order to evaluate statistically the possible relationships between these trace elements at: the ovary as an organ, each ovarian phase separately, each morphological part independent of the ovarian phase, and between cortex and medulla within the ovarian phases. The element Cs seems to have a homogenous distribution between cortex and medulla within reproductive and menopausal phase. Zinc shows a trend to have an antagonistic relation with Cs, Cr, Co, and Fe during fetal and reproductive phases and not during menopausal phase. The relationship between Zn and Cs when Fe is kept constant could be used as a tool for the decontamination of the ovary from an abnormal Cs content or for the inhibition of the accumulation of the same element to the ovarian tissue.     

Laboratory gloves as a source of trace element contamination

Contamination in a trace element laboratory can come from a variety of sources, including laboratory gloves. Therefore, vinyl and latex gloves were obtained from as many manufacturers as would supply gloves. These gloves were either prepared for acid-washing and subsequent soaking in an acid solution, or immersed in an acid solution for a duration of either 1 min or 1 h. Incubation washes were analyzed for a variety of trace elements by flame atomic abosrption spectroscopy (AAS) or inductively coupled mass spectrometry (ICP-MS). Results indicated that only three brands of vinyl gloves were acceptable for use in a trace element laboratory, whereas others had contamination of different elements. Latex gloves contained such high levels of biologically important elements that they were not considered suitable for routine trace element work. Vinyl gloves of choice should be routinely acid-washed before use in a trace element laboratory.