A human exposure study to investigate biological monitoring methods for 2-butoxyethanol

2-Butoxyethanol is a glycol ether widely used in printing inks, varnishes and cleaning fluids. As skin absorption can be significant, biological monitoring is useful in monitoring worker exposure. A number of analytes and matrices have been used previously, including 2-butoxyethanol in blood and free and total 2-butoxyacetic acid in urine. Using a combination of a volunteer study and samples from exposed workers, we compared the applicability of some of the biological monitoring markers available. We conclude that 2-butoxyethanol in blood is not a suitable marker for biological monitoring due to sampling problems. In view of the low-level exposures reported in occupational surveys, 2-butoxyethanol in breath is also unsuitable because of a lack of sensitivity. Measuring 2-butoxyacetic acid in blood is possible, although non-invasive urine samples are preferred. Free 2-butoxyacetic acid in urine has previously been widely used; however, we found that the extent of conjugation of 2-butoxyacetic acid in urine varied from 0 to 100% both within and between individuals and is not related to time, concentration or urine pH. Data from 48 exposed workers suggested that an estimated 57% (95% confidence interval 44-70%) of the total 2-butoxyacetic acid is excreted in the conjugated form, and that conjugation may be activated above a certain exposure level. Using total 2-butoxyacetic acid significantly reduced inter-individual variation. Elimination half-lives for free and total 2-butoxyacetic acid were similar (∼6 h) and there was no delay in excretion of the conjugated metabolite (peak excretion for both free and total was between 6 and 12 h after the end of exposure). In conclusion, we propose that total butoxyacetic acid (after acid hydrolysis) in urine is the biomarker of choice for monitoring exposure to 2-butoxyethanol. Urine samples should be collected post-shift towards the end of the working week.     

Mitochondrial DNA variation and genetic structure in populations of Drosophila melanogaster

The understanding of the genetic structure of a species can be improved by considering together data from different types of genetic markers. In the past, a number of worldwide populations of Drosophila melanogaster have been extensively studied for several such markers, including allozymes, chromosomal inversions, and quantitative characters. Here we present results from a study of restriction- fragment-length polymorphisms of mitochondrial DNA (mtDNA) in 92 isofemale lines from many of the same geographic populations of D. melanogaster. Eleven restriction enzymes were used, of which four revealed restriction-site polymorphism. A total of 24 different haplotypes were observed, of which 18 were unique to single populations. In many populations, the unique haplotypes have reached high frequency without being observed in neighboring populations. A Wagner parsimony tree reveals that mutationally close variants show geographical clumping, suggesting local differentiation of mtDNA in populations. The Old-World and the New-World populations are differentiated, with the predominant Old-World haplotype being virtually absent from the New World. These results contrast with those for the nuclear genes, in which many loci show parallel clines in different continents, and suggest a common origin of D. melanogaster populations in North America.      

中国高山ping亚属（Subgerus Alticola）的系统类与分布

高山ｐｉｎｇ亚属广布于中亚山地，即从喜马拉雅山、兴都库库会经帕米尔、天山、西茂而至图瓦、抗爱山和贝加尔湖一带。中国过去仅记录２种：银色高山ｐｉｎｇ（Ａｌｔｉｃｏｌａ ａｒｇｅｎｔａｔｃｓ Ｓｅｖｅｒｔｓｏｖ；有时定作劳氏高山ｐｉｎｇＡ．ｒｏｙｌｅｉ的一亚种）和斯氏高山ｐｉｎｇ。本文依据形态学资料和采用判别函数分析的方法，对该亚属进行了研究。我们认为中国高山ｐｉｎｇ至少有３个以上的物种存在，现概述于